1. 假体材料的创新与性能优化
1.1 传统材料的表面改性与性能提升
膝关节置换术中，钴铬钼（CoCrMo）合金和超高分子量聚乙烯（UHMWPE）是常用的传统假体材料。然而，这些材料的长期使用会面临磨损和腐蚀问题，影响假体的寿命和临床效果。为了解决这些问题，研究人员致力于通过表面改性技术来提升其性能。
对于UHMWPE，虽然其在体内具有良好的氧化稳定性，尤其是在采用环氧乙烷（EtO）灭菌后，但在短期植入（长达10年）中仍可能出现轻微氧化和表面损伤，例如烧伤、磨损和第三体磨损，但尚未发现分层现象，且机械性能未受明显影响 1。为了进一步提高UHMWPE的耐磨性，表面改性技术，如交联或加入抗氧化剂，已被广泛研究。此外，UHMWPE与金属胫骨托盘之间的微动摩擦磨损是磨损碎片的重要来源 2。研究发现，高度抛光的金属表面能显著减少UHMWPE的磨损，例如，高度抛光的钛合金表面比喷砂处理的钛合金表面减少了近20倍的聚乙烯磨损 2。
对于金属材料，特别是钛合金（Ti6Al4V），其耐磨性不如钴合金（CoCrMo），因此提高钛合金的摩擦学性能至关重要 3。氮离子注入技术已被证实可以有效提升Ti6Al4V合金的耐磨损腐蚀能力 45。通过氮扩散硬化处理，Ti6Al4V合金的表面形貌、电化学性能和表面硬度均得到改善。氮扩散硬化后的钛合金样品（N-Ti64）具有更明显的晶粒结构和更结节的表面，粗糙度值显著增高（P<0.01），同时表现出与对照组Ti64相当的腐蚀行为和显著提高的表面硬度 3。这意味着N-Ti64合金在抵抗机械-电化学降解方面具有潜力，能够更好地抵抗刮擦和微动损伤 3。此外，钛氮化物（TiN）和氧化锆氮化物（ZrN）涂层也被应用于金属假体表面，通过增加表面硬度、降低摩擦系数来减少磨损，并提高耐腐蚀性，从而延长假体的使用寿命。这些表面改性技术有助于减少磨损碎片的产生，进而降低与磨损和腐蚀相关的骨溶解和无菌性松动风险 67。
1.2 新型生物材料的开发与临床探索
除了传统材料的性能提升，新型生物材料的开发也为膝关节置换术假体的创新提供了广阔前景。这些材料主要关注生物相容性、可降解性以及力学性能的优化，以期更好地模拟天然组织功能并减少长期并发症。
生物可吸收材料，如聚乳酸（PLA）及其衍生物（如聚左旋乳酸 PLLA、聚己内酯 PCL），在临时支撑或辅助固定方面展现出巨大潜力。例如，在前交叉韧带（ACL）重建术中，PLA基管状植入物已被用于支持肌腱移植物在股骨和胫骨骨隧道中的稳定性，并刺激愈合过程8。研究表明，PLA基植入物能促进肌腱移植物与骨的整合，并在术后6周和12周时改善膝关节的机械稳定性，显著提升了膝关节的生物力学参数，例如在12周后，与对照组相比，PLA植入组的胫骨-股骨关节机械稳定性更好，线力-应变功能和失效应变值均有所降低8。此外，聚乳酸干扰螺钉在ACL重建中也能提供与金属干扰螺钉相似的初始固定强度，且其可吸收特性避免了金属伪影和二次手术移除的需要910。聚乙醇酸（PGA）涂覆聚乳酸/己内酯的生物可吸收半月板支架在部分半月板切除术后，已被用于恢复膝关节的正常运动学和生物力学力，尤其对年轻患者具有特殊的临床价值11。这些生物可吸收材料在膝骨关节炎的治疗中也显示出潜力，通过药物递送系统减少炎症和僵硬，并最大化恢复膝关节活动能力12。
陶瓷基复合材料是另一种重要的创新方向，旨在提高假体的生物相容性和力学性能。尽管陶瓷材料因其优异的耐磨性和生物相容性已广泛应用于髋关节假体，但在全膝关节置换术中尚未得到成功应用，主要原因在于其在严格的表面质量要求下，加工面临巨大挑战13。然而，高韧性生物陶瓷的出现，如氧化铝（Alumina），为全陶瓷膝关节假体带来了希望。氧化铝内侧枢轴全膝关节假体已被引入以模拟生理性膝关节运动学并减少聚乙烯磨损14。一项对氧化铝内侧枢轴TKA假体进行的长期研究显示，在至少10年的随访期内，其临床效果优异，10年生存率达到99.1%14。这表明陶瓷材料在膝关节置换中的应用潜力巨大，能够显著减少磨损并提高假体的长期稳定性。除了氧化铝，一些研究也探索了将陶瓷与聚合物结合，形成陶瓷聚合物复合材料，以期结合两者的优点，例如聚氨酯（Polyurethane）作为一种弹性体材料，其力学性能与天然关节软骨更接近，早期研究显示其作为全膝关节表面置换材料具有良好性能，尤其是在减少磨损颗粒和炎症反应方面表现出优势1516。这些新型材料的不断发展，有望解决传统假体材料存在的长期磨损和生物相容性问题，从而提升患者的临床结局和生活质量。
2. 假体设计的优化策略与生物力学匹配
2.1 从“标准化”到“个性化”的设计理念转变
膝关节置换术（TKA）的传统方法通常采用“标准化”假体设计，即使用预先制造的、尺寸固定的假体组件。然而，人体的膝关节解剖结构和生物力学特性存在显著的个体差异，标准化的假体往往难以完美匹配所有患者的独特需求，这可能导致术后关节功能不佳或患者满意度较低 17。因此，假体设计理念正逐步从“标准化”向“个性化”转变，旨在为每位患者提供量身定制的解决方案，以更好地恢复膝关节的天然解剖结构和运动学功能 1819。
患者特异性假体（Patient-Specific Implants, PSI）是这一转变的核心，其设计方法主要依赖于先进的影像学技术（如CT或MRI）和三维（3D）重建技术 2021。通过这些技术，可以精确获取患者膝关节的骨骼解剖数据，并在此基础上进行虚拟手术规划和假体设计。3D打印技术在个性化假体制造中发挥了关键作用，它能够根据虚拟设计文件直接制造出与患者骨骼结构高度匹配的假体组件或手术导板 202223。
个性化假体在复杂膝关节畸形患者中展现出显著优势：
- 提高匹配度和生物力学性能：与标准假体相比，个性化假体能够更好地适应患者的骨骼形态，减少骨骼切除量，并优化假体与骨骼之间的应力分布，从而降低磨损和松动的风险 2425。例如，计算分析显示，定制化假体在步态和深蹲负荷条件下，聚乙烯衬垫的接触应力分别降低了18%和24%，且其运动学行为更接近天然膝关节 24。一项研究对比了定制化双室膝关节置换（BKR）与标准全膝关节置换（TKR）的步态分析，发现BKR患者在屈伸力矩和旋转方面表现出更好的机械优势，更接近健康对照组 26。
- 优化手术规划和执行：患者特异性器械（PSI）如3D打印的切割导板，可以在术前根据个性化规划制作，指导外科医生在术中进行精确的骨骼切割和假体定位 2123。这不仅提高了手术的精确性和可重复性，还可能缩短手术时间，减少手术中对器械托盘的需求 2021。
- 改善临床功能和患者满意度：通过更好地恢复膝关节的天然运动学和生物力学特性，个性化假体有望提升患者的术后功能，实现“遗忘关节”的目标，即患者感觉不到关节置换的存在 171819。一项前瞻性研究比较了个性化TKA与标准TKA在个性化冠状面力线调整下的功能结果，结果显示个性化TKA组在“遗忘关节评分”（FJS）、新IKS评分和Oxford评分上均显著优于标准组，表明个性化假体能带来更好的临床效果 27。
- 处理复杂病例的优势：对于伴有严重骨缺损或复杂畸形的患者，标准假体可能无法提供足够的支撑或恢复正常的解剖结构。3D打印技术能够根据患者的具体情况设计和制造定制化的重建方案，例如在肿瘤假体周围出现严重假体周围骨折时，3D打印技术辅助的个体化重建能够精确恢复膝关节的解剖和功能 28。
尽管个性化假体展现出巨大的潜力，但其在制造质量的一致性和经济可行性方面仍面临挑战，尤其是在常规应用中 22。然而，随着技术的不断进步，个性化假体有望成为未来膝关节置换术的主流趋势。
2.2 基于生物力学的功能化设计
在膝关节置换术假体设计中，对膝关节生物力学的深入理解是实现功能优化的关键。传统的机械对齐（Mechanical Alignment, MA）策略旨在实现下肢的力线中立，但这通常会改变膝关节的天然运动学和软组织平衡，有时导致患者术后满意度不高 29。因此，运动学对齐（Kinematic Alignment, KA）和功能对齐（Functional Alignment, FA）等新理念应运而生，旨在更精确地恢复膝关节的天然运动学和功能 30。
运动学对齐（KA）与功能对齐（FA）对假体组件位置和软组织平衡的影响：
运动学对齐（KA）：KA 的核心思想是恢复个体膝关节病前的天然解剖形态和运动学特征 29。这种方法通过将假体组件精确地放置在与患者股骨髁和胫骨平台软骨下骨表面平行的位置，尽可能地重建患者独特的关节线和角度 30。KA 旨在最小化骨切除量，并避免过度松解软组织，从而保留天然的韧带张力，使关节运动更接近生理状态。然而，KA 的“安全范围”以及其对假体长期生存率的影响，目前仍在研究中 29。
功能对齐（FA）：FA 是在机器人辅助手术背景下发展起来的一种相对较新的对齐概念 31。它综合了KA的原则，并在此基础上进一步优化，通过调整假体植入位置，在最小程度牺牲软组织完整性的前提下，实现伸直和屈曲间隙的平衡 3233。FA 旨在恢复非关节炎膝关节的平面和倾斜度，同时限制软组织松解，以保持软组织包膜的完整性 3233。研究表明，采用FA技术进行机器人辅助全膝关节置换（TKA）能够实现髌股关节内侧和外侧间隙在10°、45°和90°屈曲时的软组织张力平衡 32。与机械对齐相比，FA通常需要更少的软组织松解，从而有助于维持膝关节的天然运动模式 34。FA可以更一致地恢复天然运动学，例如，与调整后的机械对齐相比，FA在很大一部分病例中能实现内侧枢转运动模式 35。尽管FA可以实现多种骨骼定位和软组织平衡的组合，但通过机器人技术进行精准评估，可以确保假体在不同的运动轨迹下保持软组织平衡 33。
FA 和 KA 等个性化对齐方法相较于传统的MA，在改善患者满意度和功能结果方面展现出潜力。例如，一项随机对照试验显示，与MA相比，FA虽然在两年的随访中总体患者报告结局（PROMs）相似，但在特定亚组（如术前冠状面力线I型）中，FA患者的“遗忘关节评分”（FJS）和KOOS-QOL评分更高 34。此外，FA能更频繁地产生内侧枢转运动模式，这与较好的临床结果相关 35。
多目标优化算法在提升径向强度、减少应力集中中的应用：
在假体设计和植入过程中，径向强度和应力集中是影响假体长期稳定性和失效的重要因素。多目标优化算法通过同时考虑多个设计目标（例如最大化强度、最小化应力集中、优化生物相容性、最小化磨损等），在复杂的约束条件下寻找最佳解决方案。
径向强度：在韧带重建（如ACL重建）中，干扰螺钉通过径向压缩移植物来提供固定强度 36。优化螺钉设计以增强径向力可以提高移植物的拔出强度。例如，研究发现，外鞘式固定装置产生的径向力显著高于干扰螺钉，这与其更高的拔出强度相关 36。通过多目标优化算法，可以设计出具有更优螺纹形状、材料和直径的干扰螺钉，以在不损伤骨隧道的情况下，最大化对移植物的径向压缩力 37。
减少应力集中：假体边缘和假体-骨界面的应力集中是导致骨吸收、假体松动和衬垫磨损的关键原因。通过有限元分析（FEA）结合多目标优化算法，设计师可以模拟不同假体几何形状、材料组合和植入位置对骨骼和假体内部应力分布的影响。例如，在半月板植入物设计中，通过优化几何形状和材料，可以使负荷分布更均匀，避免局部高应力区，从而减少对软骨的损伤并延长植入物寿命。此外，多目标优化算法还可以用于优化股骨髁和胫骨平台的曲率设计，以减少高屈曲度下衬垫的边缘载荷和应力集中，从而提高UHMWPE衬垫的抗磨损性能 38。例如，曲线对曲线（curve-on-curve）设计的后稳定膝关节假体在较高膝关节屈曲时能减少应力集中 38。
综上所述，生物力学驱动的假体设计理念，如KA和FA，正逐步取代传统的MA，以期提供更个性化、功能更佳的TKA解决方案。同时，多目标优化算法的引入，为假体结构和材料的精细化设计提供了强大的工具，有助于提升假体的径向强度和减少应力集中，从而延长假体寿命并改善患者的长期临床结局。
3. 手术技术进步对假体精准植入的推动
3.1 机器人辅助与导航技术的应用
膝关节置换术（TKA）的成功与否，很大程度上取决于假体植入的精准度。随着科技的进步，机器人辅助和导航技术已成为提高TKA手术精度和改善患者预后的重要手段。这些技术通过提供实时的解剖信息和精确的骨骼切割指导，帮助外科医生实现最佳的假体对齐和软组织平衡 30。
机器人辅助下机械对齐（MA）与运动学对齐（KA）的精准度对比：
传统的TKA主要目标是实现机械对齐（MA），即确保下肢力线呈中立位。MA旨在通过将股骨和胫骨假体组件垂直于力学轴线植入，以优化假体的长期生存率。然而，这种“一刀切”的方法可能无法充分考虑到个体患者的解剖学差异和天然运动学特征，从而导致术后功能满意度不佳 30。
运动学对齐（KA）则是一种更具个性化的策略，其核心理念是重建患者膝关节病前的天然解剖形态和运动学。KA试图通过将假体组件放置在与患者股骨髁和胫骨平台软骨下骨表面平行的位置，从而保留天然的关节线和韧带张力 3039。
机器人辅助技术在提高这两种对齐策略的精准度方面均发挥了关键作用：
- 提高精准度：多项研究表明，机器人辅助TKA（RATKA）能显著提高假体组件定位和对齐的准确性，与传统手动TKA（mTKA）相比，误差更小、离散度更窄 404142。这种更高的精准度不仅体现在冠状面和矢状面的对齐上，也体现在骨切除的深度上 41。对于KA而言，机器人系统能够根据术前规划精确执行骨骼切割，从而更准确地恢复患者的天然关节运动学 3543。
- 减少变异性：机器人辅助系统通过提供实时的可视化和触觉反馈，有效减少了外科医生操作的变异性，使得假体植入的精准度不再高度依赖于外科医生的经验 3944。
- 临床效果：尽管机器人辅助TKA在假体定位准确性上优于传统TKA，但长期随机对照试验尚未明确证实其在患者报告结局（PROMs）或假体生存率方面具有显著优势 4546。然而，早期研究显示，RATKA可能带来更快的术后恢复、更低的疼痛感和更短的住院时间 47。
术中动态软组织平衡监测对假体稳定性的影响：
膝关节的稳定性不仅仅取决于骨性对齐，更受到软组织（韧带和关节囊）张力的影响。软组织平衡不良是导致术后疼痛、功能障碍甚至假体松动和翻修的重要原因。机器人辅助和导航技术结合负荷传感器，使得术中动态监测软组织平衡成为可能。
- 实时量化平衡：负荷传感器（如VERASENSE）能够实时测量股骨和胫骨平台之间的压力，量化屈曲和伸直状态下的内侧和外侧间隙压力。这使得外科医生可以客观评估软组织张力，并根据需要进行微调，例如调整骨骼切割或进行有限的软组织松解，以达到最佳平衡 3248。
- 优化运动学：通过监测软组织平衡，外科医生可以更好地实现功能对齐（FA）的目标，即在保持软组织完整性的前提下，实现伸直和屈曲间隙的平衡 3235。一项研究发现，采用FA的机器人辅助TKA能实现髌股关节内侧和外侧间隙在不同屈曲角度下的软组织张力平衡，平均间隙压力差（ICPD）均低于15 psi 32。这种精确的软组织平衡有助于恢复膝关节的天然运动学，例如内侧枢转运动模式，从而可能提高患者满意度 35。
- 减少软组织松解：结合负荷传感器和机器人技术，外科医生可以在术中动态调整假体位置，以实现平衡，从而减少对软组织进行不必要的松解 344348。这对于保留天然韧带功能、加速术后恢复具有重要意义 44。
尽管导航技术在临床应用已有15年以上，但其广泛接受度受限于成本增加和缺乏长期优越性证据 49。然而，随着技术的不断成熟和成本效益的优化，机器人辅助和导航技术在TKA中的应用将更加普及，为患者带来更精准、更个性化的治疗方案 5051。
3.2 3D打印与计算机辅助的术前规划
在膝关节置换术（TKA）中，术前规划的精确性对于假体的成功植入和长期功能至关重要。3D打印技术和计算机辅助模拟的结合，为术前规划带来了革命性的进步，使得个性化和精准化的手术方案得以实现。
3D打印导板在骨切割、假体定位中的临床效果：
3D打印技术能够根据患者特异性的解剖数据（通过CT或MRI扫描获取），制作出高度定制化的手术器械，如切割导板（patient-specific instrumentation, PSI）。这些导板旨在帮助外科医生在术中进行精确的骨骼切割和假体定位，从而提高假体对齐的准确性。
- 提高骨切割精度与对齐效果：PSI的理念是通过术前规划和定制化导板，实现更准确的骨骼切割和假体对齐。虽然PSI旨在减少机械轴线的偏差和假体组件的内外翻或前后倾斜，以期提高手术效果，但文献中对于其能否可靠地改善术后肢体或组件对齐仍存在争议 5253。一项系统性综述和荟萃分析显示，PSI能够显著降低机械轴线排列不当的风险，并改善股骨冠状面对齐的准确性 54。然而，也有研究指出，PSI在改善影像学对齐或临床结局方面并未显示出显著优势，尤其是在降低胫骨组件冠状面异常对齐的风险方面，甚至可能略有增加 5455。
- 缩短手术时间与减少器械数量：PSI的一个明确优势是能够简化手术流程，减少术中对传统髓内或髓外定位器械的需求，从而缩短手术时间、减少出血量，并降低器械托盘的数量 53555657。例如，有研究发现PSI组的手术时间平均缩短了4.4分钟，失血量减少了37.9毫升 54，住院时间也显著缩短约8小时 55。VISIONAIRE PSI系统与传统器械相比，手术室、周转和止血带时间分别减少了7.3%、42%和15.9%，输血几率降低了53%，住院时间缩短了11.1% 57。
- 复杂病例的应用：对于一些复杂的膝关节畸形或骨肿瘤病例，3D打印技术尤其展现出其独特优势。例如，在胫骨近端巨大细胞瘤的治疗中，3D打印技术可以用于设计和生产定制化的胫骨块，以精确填充肿瘤切除后的骨缺损，并结合标准膝关节假体，维持膝关节的稳定性和功能 58。这种个性化的解决方案对于传统手术方法难以处理的复杂情况提供了有效的手段。
尽管PSI在提高对齐精度和手术效率方面存在争议，但其在特定情况下（例如，对于复杂畸形、肿瘤切除后骨缺损等，3D打印技术可用于设计定制化假体和填充物 58）的优势以及简化手术流程的潜力仍使其成为TKA术前规划的重要工具 5256。
计算机模拟技术在预测假体-骨界面应力分布的应用：
计算机模拟，特别是有限元分析（Finite Element Analysis, FEA），已成为膝关节假体设计、优化以及预测假体-骨界面力学行为不可或缺的工具 596061。通过FEA，研究人员可以在虚拟环境中模拟不同假体设计、材料选择和植入方式对膝关节生物力学的影响，从而优化假体性能并减少术后并发症的风险。
- 评估应力分布与骨整合：FEA能够精确模拟假体植入后骨骼和假体内部的应力分布。例如，研究可以使用FEA来比较全聚乙烯（APE）胫骨植入物和金属背衬（MBT）胫骨植入物的应力分布。结果显示，MBT在胫骨骨干和骨水泥界面处承受更高的负荷，而APE由于更灵活，其应力屏蔽效应较低，有助于保持骨骼健康 62。此外，FEA还可以预测不同载荷条件下，假体-骨界面的应力集中区域，这对于评估假体松动和骨折的风险至关重要 59。
- 优化假体设计与材料选择：FEA在假体设计迭代中发挥着关键作用。例如，通过FEA可以评估新型材料（如碳纤维增强聚醚醚酮，CF-PEEK）在肿瘤型膝关节假体中的应用，以优化应力分布，降低假体最大应力，并提高假体稳定性 63。混合材料（如氧化铝增韧氧化锆陶瓷与钛合金）股骨组件的FEA研究表明，它们可以降低假体内部的最大应力，并显著减少假体周围骨骼的应力屏蔽效应，从而降低术中骨折风险并改善骨整合 64。
- 预测假体行为与故障模式：FEA还可以用于预测假体在长期使用中的行为，例如磨损、疲劳失效等。通过模拟步态循环等生理载荷，FEA可以识别假体组件（特别是聚乙烯衬垫）的磨损区域和高应力区域，从而指导设计改进，以延长假体的使用寿命 6065。例如，在铰链式膝关节假体中，FEA可以用来研究旋转平台和PEEK铰链销衬套的接触特性和应力状态，确保其在各种运动下的塑性稳定性 59。
尽管FEA结果的准确性依赖于模型的建立和输入参数的精确性，但其作为一种无创、高效的分析工具，已广泛应用于膝关节假体的研发和临床前评估，为实现更安全、更有效的膝关节置换术提供了重要的科学依据 61。
4. 术后管理与并发症防控的新策略
膝关节置换术（TKA）的成功不仅依赖于精良的假体和精准的手术技术，术后的有效管理和并发症防控同样至关重要。其中，假体周围感染（Periprosthetic Joint Infection, PJI）是TKA术后最严重的并发症之一，发生率约为0.5%至2.4%，在翻修手术中甚至可高达20% 6667。PJI不仅会给患者带来巨大的痛苦和经济负担，还可能导致多次手术、功能受损，甚至截肢 6768。因此，深入研究PJI的预防和治疗策略，是提高TKA术后效果的关键。
4.1 假体周围感染的预防与治疗
PJI的预防和治疗是一个多维度、综合性的过程，涵盖术前准备、术中干预和术后管理等多个环节。
抗生素局部浓度管理（如止血带使用对头孢唑啉组织浓度的影响）：
预防性使用抗生素是TKA术前预防PJI的关键措施之一 6769。然而，抗生素要发挥有效作用，局部组织浓度（Local Tissue Concentration, LTC）必须超过典型感染微生物的最小抑菌浓度（Minimum Inhibitory Concentration, MIC）。对于常用的一代头孢菌素——头孢唑啉（Cefazolin），其在关节置换术期间的局部组织浓度尚不完全清楚 70。
多项研究探讨了止血带（Tourniquet）使用对抗生素局部浓度的影响：
- 影响局部组织渗透：在一项随机临床试验中，研究人员比较了TKA手术中使用止血带与不使用止血带患者体内头孢唑啉的全身血清浓度和局部组织（脂肪、滑膜和骨骼）浓度。结果显示，在不使用止血带的患者中，头孢唑啉在血清中的平均浓度为71.9 μg/mL，而在脂肪、滑膜和骨骼中的平均局部组织浓度分别为13.9 μg/g、27.7 μg/g和17.7 μg/g。使用止血带的患者，头孢唑啉的血清浓度相似（72.0 μg/mL），但局部组织浓度显著降低。在头孢唑啉输注后60分钟，使用止血带组的脂肪、滑膜和骨骼中的平均局部组织浓度显著低于不使用止血带组 70。这意味着止血带的使用会阻碍抗生素向手术区域组织的有效渗透，从而可能降低局部抗菌效果。
- 止血带充气时机：早期研究也曾探讨抗生素给药后与止血带充气之间的时间间隔对抗生素局部浓度的影响。一项将患者分为止血带充气前1分钟、2分钟或5分钟接受1克头孢唑啉的研究发现，抗生素给药后5分钟再充气止血带，患者软组织和骨骼中头孢唑啉的渗透率更高，能更有效地达到所需的浓度（≥4 μg/g，即MIC90的4倍） 71。这提示，即使使用止血带，适当延长抗生素给药到止血带充气的时间间隔，有助于提高局部抗生素浓度。
- 全身与局部浓度差异：总体而言，头孢唑啉在局部组织（脂肪、滑膜和骨骼）中的浓度低于全身血液浓度 6970。尽管目前的预防性头孢唑啉给药方案能提供足够的血清浓度，但TKA术中围关节组织中的浓度可能不足以有效预防假体周围感染，尤其是在使用止血带的情况下 70。
- 其他给药途径：除了静脉给药，局部给药途径也在探索中。例如，骨内（Intraosseous, IO）万古霉素给药已被证明比静脉（Intravenous, IV）给药在预防早期PJI方面更安全有效，且可以在不使用止血带的TKA手术中实现与静脉给药相似的局部组织浓度，但全身浓度显著降低 72。另一项兔模型研究也表明，骨内区域给药头孢唑啉可以维持较长时间的有效浓度，提示其在术中抗生素预防方面的潜力 73。
虽然抗生素骨水泥（Antibiotic-Loaded Bone Cement, ALBC）在关节置换术中的应用日益增多，但近期一项涵盖14个国家或地区关节置换注册数据的国际队列研究显示，对于初次TKA，使用ALBC与普通骨水泥在一年PJI翻修率方面没有统计学差异 74。这表明，ALBC的额外成本及其在降低翻修风险方面的相对价值，需要在整体医疗体系背景下进行权衡。
DAIR（清创-抗生素-假体保留）与1.5期翻修术的适应症与疗效：
当PJI发生时，及时有效的治疗至关重要。清创、抗生素和假体保留（Debridement, Antibiotics, and Implant Retention, DAIR）手术是一种在特定条件下可以考虑的治疗方案。
DAIR的适应症与疗效：DAIR主要适用于急性PJI，包括早期急性感染（症状出现至手术时间短）或急性迟发性感染 7576。DAIR的成功率高度依赖于正确的适应症选择，包括：
- 感染时机：PJI症状出现至清创时间短（通常小于3周）是DAIR成功的重要预测因素 7778。有研究显示，如果从症状到清创的时间小于3周，DAIR的成功率可显著提高 77。
- 假体状态：假体必须稳固、无松动，且软组织包膜良好 76。
- 微生物类型：某些细菌（如金黄色葡萄球菌）对DAIR治疗的响应较差，而其他类型微生物的感染可能预示着更高的成功率 7577。例如，非耐甲氧西林金黄色葡萄球菌（MRSA）的细菌种类是DAIR成功的重要因素 77。糖尿病患者的PJI微生物谱更复杂，包括金黄色葡萄球菌、铜绿假单胞菌、链球菌属和念珠菌属等，且多重微生物感染风险更高，这可能影响DAIR的疗效 79。
- 感染程度：DAIR对早期真菌性PJI（如念珠菌属感染）也可能有效，一项成功案例报道结合DAIR和氟康唑持续冲洗，并在术后进行抗真菌治疗，取得了良好的5年随访结果 80。
DAIR的整体成功率在文献中差异较大，从31%到100%不等 75。一项对1266例PJI患者进行汇总分析的研究显示，DAIR的总体成功率为57.11%。该研究还提出了一个简单的算法来预测DAIR的高成功率：满足“症状至清创时间小于3周”和“非MRSA细菌感染”这两个主要标准，并至少满足一个次要标准（如开放性清创和衬垫置换，或无类风湿性关节炎合并症），其成功率可达80.98% 77。
DAIR的局限性：对于慢性或迟发性感染，DAIR的成功率显著降低（28%-62%） 7578。在踝关节PJI中，DAIR的池化清除率为89%，而1.5期和2期翻修分别为95%和92% 68。此外，DAIR的有效性也受到患者个体因素、微生物类型、抗生素治疗持续时间以及骨科医生在DAIR时机和执行方面正确选择的影响 75。对于一些不适合二期翻修的慢性PJI患者，DAIR结合局部可降解钙基抗生素可能作为一种补救措施，显著提高感染缓解率和无感染生存期 81。
1.5期翻修术：1.5期翻修术通常指在移除假体和清创后，立即植入临时抗生素骨水泥间隔物（Spacer），并在感染控制后再次植入永久假体。这种方法介于DAIR和传统的两阶段翻修之间，通常适用于对DAAIR无效或感染较严重的急性PJI。在踝关节PJI中，1.5期翻修的感染清除率与2期翻修相似，甚至略高 68。虽然针对膝关节PJI的1.5期翻修术的专门文献相对较少，但其理念在于通过暂时移除假体和局部高浓度抗生素释放，为感染清除创造更有利条件。
总的来说，PJI的预防和治疗是一个复杂且不断发展的领域。抗生素局部浓度管理，尤其是止血带对头孢唑啉组织浓度的影响，提醒我们需优化抗生素给药策略。DAIR手术在选择合适的适应症时仍是有效的治疗方案，而1.5期翻修术则为某些复杂病例提供了进一步的治疗选择。新的防腐冲洗液也在临床试验中，例如一种由乙醇、乙酸、乙酸钠、苯扎氯铵和水组成的混合物，在DAIR手术中作为辅助工具，显示出良好的感染控制效果和安全性 82。
4.2 假体周围组织健康维护
膝关节置换术后假体周围组织的健康对于假体的长期稳定性和患者的功能恢复至关重要。骨整合的成功与否，以及术后肿胀的有效管理，是假体周围组织健康维护的两个主要方面。
骨整合促进技术（如钙磷涂层、多孔钛金属）：
骨整合是指假体与宿主骨组织之间形成直接的功能性连接，是实现骨水泥型（cementless）假体长期稳定的关键。为了促进这一过程，研究人员开发了多种技术。
- 钙磷涂层：钙磷（Ca-P）涂层，特别是羟基磷灰石（Hydroxyapatite, HA）涂层，因其与骨组织相似的化学成分和生物活性，被广泛应用于骨水泥型假体表面，以加速骨整合。HA涂层能够诱导骨细胞的生长和分化，促进新骨在假体表面的形成，从而增强假体的初期和长期稳定性。一项针对钙磷涂层多孔胫骨锥的初步临床研究显示，这些定制锥体在使用钛合金（Ti-6Al-4V）并结合特殊钙磷涂层（HX-coating）制备后，在翻修性膝关节置换术中表现出良好的功能结果 83。虽然这项研究的随访时间相对较短（平均22个月），但78.6%的影像学结果显示锥体和全膝关节置换（TKA）定位良好，且骨水泥界面处的放射线透光线极少，这表明钙磷涂层有助于实现良好的骨整合 83。此外，HA涂层还能改善假体周围骨密度，减少骨吸收，从而进一步增强假体稳定性 84。
- 多孔钛金属：多孔钛金属结构，如泡沫金属或多孔涂层，通过提供三维支架和开放的孔隙结构，允许骨组织长入假体内部，形成机械互锁，进一步提高骨整合的成功率。这些多孔结构不仅具有良好的生物相容性，还能降低假体与骨骼之间的刚度差异，减少应力遮挡效应（stress shielding），从而有利于假体周围骨组织的长期健康 85。多孔结构的设计（如孔隙率、孔径大小和互连性）是影响骨整合效果的关键因素。优化的多孔结构能够促进血管化和骨细胞的迁入与增殖。在一项尸体研究中，通过有限元分析验证了在生理负荷条件下，骨水泥型胫骨托盘与骨界面的微动。结果表明，初始假体-骨对齐对界面微动有显著影响，而适当的微动水平（通常低于150 μm）对于骨长入至关重要 86。这强调了多孔结构在促进骨整合中的生物力学作用。
在存在骨缺损的复杂翻修病例中，定制化3D打印多孔钛锥体也显示出巨大潜力。这些锥体可以根据患者的个体解剖结构进行设计和制造，以精确填充骨缺损，并提供骨长入的理想环境。早期的研究表明，这种方法能够重建严重的骨缺损，保留残余骨量，并简化手术流程 87。对于骨质疏松或骨量不足的患者（如伴有炎症性关节炎的患者），骨水泥型假体结合这些骨整合促进技术，可以提供与骨水泥型假体相当的长期稳定性 88。
术后肿胀评估（如生物阻抗谱、3D扫描）对康复进程的指导作用：
膝关节置换术后，患者普遍会出现下肢肿胀，这与术后疼痛、功能恢复延迟和患者满意度不佳密切相关 8990。准确、可靠地评估肿胀程度对于指导康复、调整治疗方案至关重要。
- 生物阻抗谱（Bioelectrical Impedance Assessment, BIA）：生物阻抗谱是一种无创、便捷的肿胀评估方法，通过测量肢体的电阻抗来估算细胞外液量，从而量化肿胀程度 8991。
- 可靠性和精确性：单频生物阻抗评估（SF-BIA）在测量TKA术后下肢肿胀方面表现出比传统周径测量法更高的可靠性和精确性 8991。SF-BIA的组内相关系数（ICC）在术后高达0.99，而周径测量法仅为0.68 89。此外，SF-BIA的最小可检测变化（MDC90）为2%，这意味着它能检测到更微小的肿胀波动，优于周径测量法的6% 89。
- 与功能恢复的关系：研究表明，术后肿胀的峰值与股四头肌力量和功能表现（如“起立-行走”时间）存在显著关联 90。例如，峰值肿胀可以解释术后两周和六周“起立-行走”时间变异性的16%和5% 90。因此，有效管理和减少早期术后肿胀的峰值，可能有助于改善患者的功能恢复。
- 参考图表：研究人员已开发出TKA术后下肢肿胀的参考图表，该图表显示术后前3天肿胀每天增加约10%，峰值通常出现在术后6-8天 92。此图表为临床医生提供了一个客观的工具，用于监测患者的肿胀恢复情况，并指导个性化的康复干预。
- 3D扫描技术：手持3D扫描技术是另一种新兴的无创肿胀评估工具，它能够快速、精确地量化膝关节肿胀体积 93。与传统的周径测量和体积测量方法相比，3D扫描能够提供更详细的表面形貌信息，并有助于估计关节腔积液和肌肉体积的变化 93。3D扫描技术不仅精度高，而且操作简便，有望成为未来临床评估TKA术后肿胀的重要工具 93。
通过这些先进的评估工具，临床医生能够更准确地监测患者的术后肿胀，及时发现异常，并调整康复计划，例如指导淋巴引流、加压包扎或药物治疗，从而优化肿胀管理，减轻患者不适，促进功能恢复，最终提高假体的长期成功率和患者满意度。
5.1 不同假体类型的长期效果对比
膝关节置换术中，单髁置换术（Unicompartmental Knee Arthroplasty, UKA）和全膝关节置换术（Total Knee Arthroplasty, TKA）是治疗终末期膝关节骨关节炎的两种主要手术方式。选择哪种假体类型，特别是对于老年患者，是一个复杂的决策过程，需要综合考虑患者年龄、活动水平、病变范围以及假体的长期生存率和并发症风险。此外，骨水泥型（Cemented）与非骨水泥型（Cementless）假体的选择也对假体寿命和翻修率有重要影响。
单髁置换（UKA）与全膝置换（TKA）在老年患者中的适应症与生存分析：
UKA通常适用于单间隔室（内侧或外侧）的终末期骨关节炎，而TKA适用于多间隔室病变。与TKA相比，UKA具有创伤小、术后恢复快、并发症少和保留更多骨量等优点 949596。然而，UKA的翻修率通常高于TKA，这是临床决策中的一个重要考虑因素。
老年患者的适应症选择：
长期生存率与翻修率对比：
- 总体现状：一项基于英国国家关节注册数据库的匹配研究比较了54,215例UKA和54,215例TKA的长期结局。结果显示，UKA的10年翻修率为12%，而TKA为5%，UKA的翻修率显著高于TKA（风险比[HR] 2.31, P < .001）。再手术率方面，UKA的10年再手术率为25%，略高于TKA的21%（HR 1.12, P < .001） 98。
- 年龄影响：然而，在不同年龄组中，UKA和TKA的风险-收益比有所不同。对于75岁及以上的老年患者，UKA的10年死亡率显著低于TKA（13.6% vs 15.5%，HR 0.86, P < .001），且并发症（包括医疗和手术相关并发症）发生率和死亡风险也更低。研究指出，如果100名75岁以上患者选择UKA而非TKA，在10年内，再手术人数会增加3人，但死亡人数会减少4人。这意味着在极老年患者中，UKA在降低死亡率方面的绝对益处可能超过其翻修率略高带来的风险 98。
- 患者满意度：虽然UKA的翻修率相对较高，但许多患者对UKA的偏好程度更高，满意度也更高 99。一项比较同一患者接受UKA和TKA的研究发现，UKA组术后血红蛋白、红细胞和白蛋白水平更高，术后炎症反应更轻，关节活动度（ROM）更好（116.4°±5.96° vs 108.4°±5.32°），尽管对下肢力线的矫正效果不如TKA 99。
- 外侧UKA：外侧UKA的临床结果和生存率相对较少报道。一项针对153名患者161个外侧UKA的单外科医生队列研究显示，在平均10年的随访期内，外侧UKA的5年生存率为98.0%，10年生存率为96.0%，15年生存率为94.5%（以翻修为终点）。即使考虑到因关节炎进展而需要额外手术的患者，生存率也分别达到97.4%、95.4%和91.3%。这表明外侧UKA对于孤立的外侧间隔室骨关节炎也是一个耐用的治疗选择 100。
骨水泥型与非骨水泥型假体的翻修率差异：
骨水泥型和非骨水泥型假体各有优缺点，其选择对假体长期稳定性和翻修率有显著影响。
骨水泥型假体（Cemented TKA）：
非骨水泥型假体（Cementless TKA）：
- 复苏与优势：近年来，随着新型生物材料和多孔涂层的出现，非骨水泥型TKA重新受到关注 101103。其概念优势包括生物性固定（骨整合）、手术效率提高以及减少骨水泥相关并发症 104。
- 骨整合：非骨水泥型假体依赖于骨长入实现生物性固定。现代非骨水泥型假体设计，结合多孔涂层和改进的表面处理技术，在年轻和老年患者中均显示出优异的生存率和功能结果 103105。一项针对非骨水泥型TKA的24年随访研究显示，无菌性松动的翻修生存率高达98% 103。
- 翻修率争议：虽然一些研究显示非骨水泥型TKA的长期翻修率与骨水泥型TKA相当甚至更优 103106，但英国国家关节注册中心的数据曾报告非骨水泥型TKA的翻修率高于骨水泥型TKA 104。这种差异可能与假体设计、外科医生经验以及不同患者群体有关。
- 特定患者群体：对于肥胖患者（特别是BMI≥35 kg/m²），非骨水泥型固定可能提供与骨水泥型固定相似或更优的植入物生存率和更低的无菌性松动率 107。对于年轻且骨质量好的患者，非骨水泥型TKA因其生物性固定和避免骨水泥相关并发症的潜力，被认为是一个更合适的选择 101。
- 短期表现：在中短期随访中，非骨水泥型胫骨固定在保留后交叉韧带的全膝关节置换术中，表现出更好的Knee Society评分和更少的疼痛，并发症和翻修率与骨水泥型固定相当 106。
总的来说，UKA和TKA的选择应根据患者的具体情况（如年龄、病变范围、活动需求）进行个体化评估。对于老年患者，UKA在降低死亡率和并发症方面的优势可能使其成为有吸引力的选择，尽管其翻修率较高。骨水泥型和非骨水泥型假体的选择也应基于最新的临床证据、假体设计和患者骨质量。现代非骨水泥型假体在骨整合技术方面的进步，使其在特定患者群体中展现出与骨水泥型假体相当甚至更优的长期效果。
5.2 患者报告结局（PROMs）的应用与优化
在膝关节置换术（TKA）中，除了客观的影像学和临床测量指标外，患者报告结局（Patient-Reported Outcome Measures, PROMs）越来越受到重视。PROMs直接反映了患者对自身健康状况和治疗效果的感知，对于全面评估手术成功率和患者满意度至关重要。传统上，Knee Injury and Osteoarthritis Outcome Score (KOOS)和Oxford Knee Score (OKS)是广泛使用的PROMs，而近年来，“遗忘关节评分”（Forgotten Joint Score, FJS）等新型PROMs的出现，为TKA术后评估提供了更细致、更贴近患者真实感受的视角。同时，人工智能（AI）辅助决策工具的应用，正在进一步提升患者满意度。
KOOS、Oxford评分等传统指标与“遗忘关节评分”等新型PROMs的互补性：
传统PROMs (KOOS, OKS)：
- KOOS：Knee Injury and Osteoarthritis Outcome Score (KOOS)是一个综合性的问卷，包含疼痛、症状、日常生活活动（ADL）、运动与娱乐功能以及生活质量（QOL）五个子量表。每个子量表评分从0到100，分数越高代表功能越好、症状越轻。KOOS广泛用于评估膝关节损伤和骨关节炎患者的症状和功能，并能有效反映TKA术后的改善情况 108。例如，一项对ATTUNE全膝关节置换系统短期结果的回顾性研究显示，KOOS评分中的疼痛、症状、ADL和QOL均有显著改善，平均疼痛得分为82.7，QOL得分为78.6 108。此外，研究发现KOOS及其衍生指标（如KOOS-JR）的最小临床重要差异（MCID）在法国TKA患者中分别为14和14，表明这些指标在评估临床改善方面的有效性 109。
- OKS：Oxford Knee Score (OKS)是一个简洁的12项问卷，主要评估膝关节疼痛和功能。OKS评分范围为0到48，分数越高代表功能越好、疼痛越少。OKS也是TKA术后常用的评估工具，能够有效反映患者的整体满意度和功能恢复情况 108。一项研究显示，TKA术后OKS的平均得分为35 108。在法国TKA患者中，OKS的MCID平均为10，进一步证实了其在临床实践中的应用价值 109。
新型PROMs (Forgotten Joint Score, FJS)：
- “遗忘关节评分”（FJS）：FJS是一个较新的PROMs，旨在衡量患者对人工关节的“遗忘”程度，即患者在日常生活中是否能感觉不到人工关节的存在。其理念是，一个真正成功的关节置换应是患者能够完全“遗忘”它的存在，而不是仅仅忍受它。FJS的评分范围为0到100，分数越高代表患者越能“遗忘”其人工关节，满意度越高。研究表明，FJS对TKA术后患者的满意度有很好的区分能力 110。
- 互补性：KOOS和OKS更多关注疼痛缓解和功能恢复的程度，而FJS则从患者主观感受出发，衡量关节的“正常化”程度。例如，一项研究比较了患有Kellgren-Lawrence（KL）3级和4级骨关节炎的患者在TKA术后2年的KSS和FJS评分，发现两组患者在FJS评分上没有显著差异，这表明即使传统评分相似，FJS也能提供额外的患者体验信息 111。FJS能够捕捉到KOOS和OKS可能无法完全体现的细微差别，特别是在评估患者对关节置换的最终心理接受度和“正常感”方面。有研究指出，MCID for FJS 在KA患者中表现出良好的区分能力，其阈值根据方法不同在22到76之间，且MCID和患者可接受症状状态（PASS）的阈值会因方法不同而有所差异 110。因此，将传统PROMs与FJS结合使用，可以更全面、更细致地评估TKA术后的效果，不仅关注疼痛和功能，也关注患者的主观感受和生活质量，从而提供更全面的临床评估。
人工智能辅助决策工具对患者满意度的提升作用：
人工智能（AI）在膝关节置换领域正发挥越来越重要的作用，尤其是在术前规划、个性化治疗以及提高患者满意度方面 112。AI辅助决策工具通过整合大量患者数据，提供个性化的风险评估和结局预测，从而帮助患者做出更明智的治疗选择，并可能提高术后满意度。
- 个性化结局预测：AI和机器学习（ML）算法能够分析患者的临床数据（如年龄、BMI、共病、术前PROMs等），预测TKA术后患者实现最小临床重要差异（MCID）的可能性。例如，一项研究开发了ML算法来预测KOOS-PS在TKA术后1年实现MCID的情况，发现弹性网惩罚逻辑回归模型表现最佳（C-统计量为0.77），其最重要的预测变量包括术前KOOS-PS分数、术前VAS疼痛评分、术前阿片类药物使用情况、术前PROMIS心理健康评分、年龄和性别 113。这些预测工具可以帮助患者了解他们术后功能改善的个体化可能性，从而调整其对TKA的期望。
- 增强共同决策（Shared Decision-Making, SDM）：AI赋能的患者决策辅助工具能够结合患者教育、偏好评估和个性化结局预测，极大地提升决策质量。一项随机临床试验比较了AI赋能的决策辅助工具与仅提供教育材料的效果。结果显示，使用AI决策辅助工具的患者在决策质量、共同决策水平、满意度以及4-6个月时的功能结局（KOOS JR评分平均提高4.9分）方面均有显著改善，而不会显著增加咨询时间或TKR手术率 114。这意味着AI工具能够帮助患者更好地理解治疗方案，并与医生共同制定最适合自己的治疗计划，从而提高患者的参与感和满意度。
- 降低不满意率：约有五分之一的TKA患者对术后结果不满意 115。通过预测工具，如SMART Choice（Patient Prognostic Tool for Total Knee Arthroplasty），可以在术前评估患者在TKA后改善或恶化/无变化的概率。这项工具旨在帮助患者在没有临床医生参与的情况下使用，从而影响他们对手术的意愿，特别是在患者TKA旅程的早期阶段 115。通过更准确的术前风险分层和结果预测，AI工具可以筛选出那些可能对TKA不满意的高风险患者，以便提供额外的咨询或替代治疗方案，从而减少术后不满意率。
- 识别非技术因素：除了生物力学和生理因素，患者体验还受到许多非技术因素的影响。一项利用自然语言处理（NLP）技术分析TKA患者术后评论的研究发现，尽管患者满意度不一定与客观的手术结局（如疼痛强度、住院时间、KOOS JR评分）相关，但负面评论的主要主题包括病房条件和沟通效率低下 116。AI工具未来可以进一步应用于分析这些非结构化数据，帮助医疗机构识别并改进影响患者体验的非临床因素，从而全面提升患者满意度。
综上所述，PROMs作为膝关节置换术结局评估的重要组成部分，正从传统的症状和功能评估向更全面的“遗忘关节”理念演进。KOOS、OKS和FJS的结合使用，能够提供更细致和人性化的评估。同时，AI辅助决策工具通过个性化预测和增强共同决策，有望显著提升患者的术前准备水平和术后满意度，是未来TKA临床实践的重要发展方向。
6. 未来发展趋势与挑战
6.1 智能化与个性化的融合
膝关节置换术（TKA）正迎来智能化和个性化融合的时代，这不仅体现在假体材料和设计的革新上，更深入到术后功能监测和术前个性化规划中。这一趋势旨在通过先进技术，提升TKA的精准性、有效性及患者满意度，从而实现更优的长期临床结局。
智能假体（如嵌入传感器的胫骨平台）在术后功能监测中的潜力：
传统的TKA术后评估主要依赖于患者报告结局（PROMs）、影像学检查和临床体格检查。然而，这些方法往往无法提供实时、客观且持续的关节功能数据。智能假体的出现，特别是嵌入传感器的假体组件，为术后功能监测带来了革命性的潜力。
- 实时、客观的数据采集：通过在假体（如胫骨平台）中嵌入微型传感器，可以实时监测膝关节在日常活动中的各种生物力学参数，例如载荷分布、运动范围、关节内压力以及假体与骨界面之间的微动等。这些数据可以无线传输到外部设备进行分析，为临床医生提供前所未有的客观信息。
- 载荷分布和运动学监测：嵌入传感器的假体可以精确测量行走、上下楼梯等日常活动中膝关节的载荷分布和运动学轨迹。这有助于评估假体植入的生物力学效果，识别潜在的过度载荷区域，从而预防假体松动或磨损。
- 早期并发症预警：通过持续监测关节的温度、PH值或某些生物标志物，智能假体可能在感染、炎症或其他并发症发生早期就发出预警，从而实现早期干预，避免更严重的后果。
- 康复指导和优化：实时反馈的运动数据可以为患者提供个性化的康复指导。例如，如果传感器检测到某种运动模式对假体产生不良应力，系统可以提示患者调整步态或运动方式，以优化康复进程，提高功能恢复效率。
- 长期疗效评估和研究：智能假体能够收集大量真实世界数据（Real-World Data），为TKA的长期疗效评估和假体设计改进提供宝贵的依据。通过分析不同患者群体、不同假体设计在长期使用中的表现，研究人员可以更好地理解影响TKA成功率的因素，并为未来的假体研发提供方向。
尽管智能假体仍处于早期研究阶段，面临着传感器微型化、能量供应、数据传输安全和生物相容性等挑战，但其在提供个性化、实时术后监测方面的巨大潜力，预示着TKA术后管理将从被动评估转向主动干预。
AI算法在术前个性化假体设计的应用前景：
人工智能（AI）和机器学习（ML）算法正在彻底改变TKA的术前规划和假体设计方式，推动膝关节置换从“标准化”向“极致个性化”发展。
- 精准的术前规划和患者特异性设计：
- 基于影像学的3D重建与分析：AI算法可以自动从患者的CT或MRI影像数据中进行精确的骨骼和软组织3D重建，识别解剖标志点，并评估膝关节的畸形程度和骨缺损情况。这些信息是设计个性化假体和手术导板的基础。
- 个性化假体几何优化：AI算法能够学习大量患者的解剖数据和TKA术后功能结果之间的复杂关系。基于这些学习到的模式，AI可以为每位患者推荐或生成最佳的假体几何形状和尺寸，以最大程度地匹配患者的天然解剖结构，优化运动学和软组织平衡，并减少应力集中。
- 预测软组织平衡：结合有限元分析（FEA）和机器学习，AI可以预测不同假体植入方案对软组织张力、韧带功能和关节间隙的影响。这有助于外科医生在术前模拟和选择最佳的手术策略，以实现理想的软组织平衡，减少术中软组织松解的需求。
- 手术风险预测与并发症防范：AI算法可以整合患者的临床病史、影像学特征、共病情况等多元数据，预测术后并发症（如感染、松动、功能不满意等）的风险。这使得外科医生能够在术前识别高风险患者，并采取相应的预防措施，从而提高手术安全性。例如，一项利用机器学习分析反式肩关节置换术（rTSA）术后并发症的研究发现，患者特异性风险因素对并发症预测模型的贡献大于植入物设计配置，凸显了AI在识别高风险患者方面的潜力 117。
- 决策支持与教育：AI辅助决策工具能够通过分析大量历史数据和研究结果，为外科医生提供最佳实践建议，支持他们做出更明智的治疗决策。同时，AI也可以用于生成个性化的患者教育材料，帮助患者更好地理解手术过程、预期结果和潜在风险，从而提高患者的参与度和满意度。
- 机器人辅助手术的协同优化：AI算法可以与机器人辅助手术系统相结合，进一步提高手术的精准性和效率。例如，AI可以为机器人提供更精细的骨切除路径和假体定位方案，而机器人则负责精确执行这些方案。这种人机协作模式将使TKA手术达到前所未有的精度水平，因为机器人辅助技术本身就能提升全膝关节置换术的精确性与准确性 118。
综上所述，智能化与个性化的融合是未来TKA发展的核心驱动力。智能假体将提供持续、客观的术后功能监测，而AI算法则将在术前个性化假体设计和手术规划中发挥主导作用。这些技术的结合有望显著提升TKA的治疗效果，改善患者的生活质量，并推动骨科领域进入一个全新的精准医疗时代。
6.2 新技术转化的挑战与多学科协作
膝关节置换术（TKA）领域的新技术，包括生物可吸收材料、机器人辅助手术和3D打印个性化假体，虽然展现出巨大的潜力，但在从研究到临床应用的转化过程中，仍面临诸多挑战。这些挑战不仅涉及技术本身的成熟度、安全性和成本效益，更需要多学科之间的紧密协作才能有效克服。
生物可吸收材料的长期安全性验证：
生物可吸收材料在TKA中的应用，如用于临时固定或辅助修复，其主要优势在于可随时间降解并被人体吸收，避免了二次手术取出，并可能促进天然组织的修复。然而，其长期安全性是当前面临的首要挑战：
- 降解产物的生物相容性：生物可吸收材料在体内降解会产生各种代谢产物。这些产物在浓度较高或降解速率过快时，可能引发局部炎症反应、酸中毒、组织毒性，甚至影响细胞的正常功能。虽然聚乳酸（PLA）等常用材料的降解产物（如乳酸）是人体正常代谢的中间产物，但其在局部高浓度下的长期影响仍需严格评估。
- 力学性能的稳定性和匹配性：生物可吸收材料在降解过程中，其力学性能会逐渐下降。如何在降解过程中维持足够的力学强度，以支撑组织修复或提供必要的稳定性，同时避免过早失效或长期残留，是设计上的难点。此外，降解速率与人体组织愈合速率的匹配也至关重要。
- 感染风险：一些生物可吸收材料可能会改变局部微环境，甚至可能成为细菌黏附的良好基质，从而增加感染风险。尽管有研究探索将抗菌剂整合到可吸收材料中以降低感染，但其长期有效性和安全性仍需验证。
- 长期临床数据缺乏：尽管生物可吸收材料在其他骨科领域（如螺钉、缝线）已有广泛应用，但在TKA中作为主要承重或长期接触组件的应用仍处于早期阶段。缺乏大规模、长期的随机对照临床试验数据来证明其在膝关节置换中的优势和长期安全性，是其广泛应用的主要障碍。
机器人与3D打印技术的成本效益分析：
机器人辅助手术和3D打印技术在提高TKA的精准度和个性化方面具有显著优势，但其高昂的成本是当前限制其普及的关键因素。
- 初始投资与维护成本：机器人辅助手术系统的前期购买成本通常高达数百万美元，且需要持续的维护、耗材和人员培训费用。3D打印设备也需要较高的初始投入和运行成本。这些高成本最终可能会转嫁给患者或医疗系统，增加医疗负担。
- 手术时间与效率：虽然机器人辅助手术能够提高精度，但在一些情况下，手术时间可能会延长，尤其是在初期学习阶段，这会增加手术室的使用成本。尽管有研究表明，个性化器械（如PSI）可以缩短手术时间，减少器械托盘数量，从而带来经济效益 ，但这些效益是否能完全抵消3D打印定制化产品的成本，仍需深入研究。
- 患者受益与成本的权衡：尽管机器人辅助TKA在假体定位准确性上优于传统TKA，但尚未有足够的长期随机对照试验能够明确证明其在患者报告结局（PROMs）或假体生存率方面具有显著优势 。如果患者受益的增量不足以抵消其高昂的成本，那么这些技术的广泛采纳将面临阻碍。例如，导航技术自临床应用以来已有15年以上，但其广泛接受度仍受限于成本增加和缺乏长期优越性证据 119。
- 医疗支付体系的适应性：当前的医疗支付体系可能尚未完全适应这些高新技术。如何合理定价、制定相应的报销政策，以鼓励技术创新和应用，同时避免过度医疗，是政策制定者面临的挑战。
材料科学、生物力学与临床研究的协同创新需求：
TKA领域的未来发展需要打破学科壁垒，促进材料科学、生物力学和临床医学之间的紧密协作。
- 材料科学与生物医学工程的交叉：新型生物材料的开发，如功能梯度材料、智能材料（如形状记忆合金、自修复材料）以及具有抗菌、抗炎功能涂层材料，需要材料科学家和生物医学工程师的紧密合作。他们需要理解生物学环境的复杂性，设计出在体内具有理想生物相容性、力学性能和长期稳定性的材料。
- 生物力学与假体设计的融合：生物力学研究能够揭示膝关节的天然运动学和受力机制，为假体设计提供理论指导。通过计算生物力学模拟（如有限元分析）和实验验证，可以优化假体的几何形状、材料选择和植入位置，以减少应力集中、改善运动学、延长假体寿命。这需要生物力学专家与假体设计师、骨科医生紧密合作，将生物力学原理转化为可临床应用的假体产品。
- 临床研究与转化医学的桥梁：实验室和工程设计阶段的创新成果，最终需要通过严格的临床研究进行验证。这包括体外实验、动物模型研究、人体临床试验（从早期安全性到后期疗效评估），以确保新技术和新材料的安全性和有效性。临床医生需要将临床需求反馈给科研人员，共同设计研究方案，并对研究结果进行解读和转化。
- 多学科团队协作：例如，在加速康复外科（ERAS）的实施中，强调多学科协作的重要性。成功的实施依赖于骨科医生、护士、物理治疗师、麻醉师等组成的团队共同努力，通过知识共享和协同工作来优化护理流程 120121122。这种模式同样适用于新技术的转化：材料科学家、生物力学工程师、计算机科学家、外科医生和政策制定者等需要共同参与，形成一个高效的协同创新网络，才能将前沿技术成功地转化为患者受益的临床实践。
总之，膝关节置换术假体的未来发展，既充满希望也伴随挑战。克服生物可吸收材料的长期安全性问题、进行全面的成本效益分析，并促进材料科学、生物力学和临床研究的深度融合与协同创新，将是推动这些先进技术走向临床普及的关键。
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参考文献
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Daniel MacDonald, Josa Hanzlik, Peter Sharkey, et al.
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BACKGROUND: Gas sterilization (eg, ethylene oxide [EtO] and gas plasma) was introduced for polyethylene to reduce oxidation due to free radicals occurring during radiation sterilization. Recently, oxidation has been observed in polyethylenes with undetectable levels of free radicals, which were expected to be oxidatively stable. It is unclear whether in vivo oxidation will occur in unirradiated inserts sterilized with EtO. QUESTIONS/PURPOSES: We analyzed the oxidation, mechanical behavior, and surface damage mechanisms of tibial inserts of a single design sterilized using EtO. METHODS: We collected 20 EtO-sterilized tibial inserts at revision surgeries. We assessed oxidative using Fourier transform infrared spectroscopy and mechanical properties using the small punch test. Surface damage was assessed using damage scoring techniques and micro-CT. RESULTS: Oxidation indexes were low and uniform between the regions. The subtle changes did not affect the mechanical properties of the polymer. The dominant surface damage modes included burnishing, abrasion, and third-body wear. There was no evidence of delamination in the retrievals. CONCLUSIONS: The retrieved EtO-sterilized UHMWPE retrievals remained stable with respect to both oxidative and mechanical properties for up to 10 years in vivo. We did observe slight measurable amounts of oxidation in the inserts; however, it was far below levels that would be expected to compromise the strength of the polymer. CLINICAL RELEVANCE: Due to the stable oxidative and mechanical properties, EtO-sterilized tibial components appear to be an effective alternative to gamma-sterilized inserts, at least in short-term implantations.
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Retrieval studies have shown that the interface between the ultra-high molecular weight polyethylene insert and metal tibial tray of fixed-bearing total knee replacement components can be a source of substantial amounts of wear debris due to fretting micromotion. We assessed fretting wear of polyethylene against metal as a function of metal surface finish, alloy, and micromotion amplitude, using a three-station pin-on-disc fretting wear simulator. Overall, the greatest reduction in polyethylene wear was achieved by highly polishing the metal surface. For example, highly polished titanium alloy surfaces produced nearly 20 times less polyethylene wear compared with blasted titanium alloy, whereas, decreasing the micromotion amplitude from 200 to 50microm produced approximately four times less polyethylene wear for the same blasted titanium alloy surface. Although the effect of the metal alloy was much smaller than the effect of metal surface roughness or the micromotion amplitude, CoCr discs produced slightly greater polyethylene fretting wear than titanium alloy discs under each condition. The results are essential in design and manufacturing decisions related to fixed-bearing total knee replacements.
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Mechanical-electrochemical interactions accelerate corrosion in mixed-metal modular hip prostheses. These interactions can be reduced by improving the modular component machining tolerances or by improving the resistance of the components to scratch or fretting damage. Wrought cobalt-alloy (CoCrMo) is known to have better tribological properties compared to the titanium alloy (Ti64). Thus, improving the tribological properties of this mixed-metal interface should center around improving the tribological properties of the Ti64 alloy. This study used scanning probe microscopy (contact, tapping and phase contrast mode), scanning electron microscopy, corrosion testing, and microhardness testing to determine the effect of a nitrogen-diffusion hardening process on the surface morphology, electrochemistry and surface hardness of the Ti64 alloy. The nitrogen-diffusion-hardened titanium alloy samples (N-Ti64) had a more pronounced grain structure, more nodular surface, and significantly (P<0.01) higher mean roughness values than the control-Ti64 samples. The N-Ti64 samples also exhibited at least equivalent corrosion behavior and a definite increase in surface hardness compared to the control Ti64 samples. The equivalent corrosion behavior and improved surface hardness indicate the potential for N-Ti64 samples to resist similar and mixed-metal scratch and fretting damage. The use of N-Ti64 as opposed to control-Ti64 may therefore reduce the occurrence of mechanical-electrochemical degradation in mixed-metal modular total hip prostheses.
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Wear-accelerated corrosion rates at constant anodic potentials were evaluated for unimplanted and nitrogen-ion-implanted surgical Ti-6Al-4V while wearing against ultrahigh-molecular-weight polyethylene at stress levels up to 6.90 MPa (1000 psi). The ion implantation processing was found to reduce the wear corrosion rates in both saline and serum solutions at all applied stress levels. During wear testing, all of the ion-implanted surfaces remained visually unchanged from the polished condition. However, many of the unimplanted surfaces developed damage zones characterized by wear tracks and black wear debris. A surface-damage mechanism is proposed and discussed which involves disruption of the Ti-6Al-4V protective oxide film, subsequent entrapment of oxide particles in the polyethylene, then self-perpetuating damage due to the abrasive action of the embedded particles.
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The influence of nitrogen-ion implantation on the wear-accelerated corrosion behavior of surgical Ti-6Al-4V was studied. Nonpassivated and prepassivated unimplanted Ti-6Al-4V specimens were employed as controls for comparison. Corrosion rates as a function of time at open-circuit corrosion potentials were electrochemically measured in saline and serum solutions under both static and wear conditions. The wear parameters simulated those of a total artificial hip under average walking conditions. The results indicated that prepassivation of the control material was beneficial under static-corrosion conditions, but not under wear-corrosion conditions. The nitrogen-ion implantation process was found to significantly improve the material's resistance to wear-accelerated corrosion in both saline and serum solutions.
6Are there biological markers for wear or corrosion? A systematic review.PubMed
D Rick Sumner, Ryan Ross, Ed Purdue
Clin Orthop Relat Res. 2014 Dec;472(12):3728-39. doi: 10.1007/s11999-014-3580-3.
BACKGROUND: Identification of biomarkers associated with wear and tribocorrosion in joint arthroplasty would be helpful to enhance early detection of aseptic loosening and/or osteolysis and to improve understanding of disease progression. There have been several new reports since the last systematic review (which covered research through mid-2008) justifying a new assessment. QUESTIONS/PURPOSES: We sought to determine which biomarkers have the most promise for early diagnosis and monitoring of aseptic loosening and/or osteolysis related to wear or corrosion in total joint arthroplasty. METHODS: We performed a systematic review using MEDLINE and EMBASE databases, covering the period through December 2013, and identified 1050 articles. We restricted the definition of biomarker to biomolecules and imaging parameters useful for diagnosis and monitoring of disease progression, only including articles in English. We chose 65 articles for full review, including 44 from the original search and 21 from subsequent hand searches. We used the 22 articles in which patients with total joint arthroplasty who had aseptic loosening and/or periimplant osteolysis unrelated to sepsis had been compared with patients with total joint arthroplasty with stable implants. There were 90 comparisons of these two patient populations involving 35 different biomarkers. RESULTS: Diagnostic accuracy was assessed in nine of the 90 comparisons with the highest accuracy found for tartrate-resistant acid phosphatase 5b (0.96), although a separate comparison for this biomarker found a lower accuracy (0.76). Accuracy of > 0.80 was also found for crosslinked n-telopeptide of type I collagen, osteoprotegerin, and deoxypyridinoline. The most studied markers, tumor necrosis factor-α and interleukin-1β, were found to differ in the affected and control groups in < 30% of the comparisons. Thirty of the 35 biomarkers were studied in four or fewer separate comparisons with nearly half of the biomarkers (17) studied in only one comparison. Many of the comparisons were not able to eliminate a number of confounding variables, and there was only one prospective study. CONCLUSIONS: Currently, there are no validated biomarkers for early diagnosis and monitoring of the biological sequelae of wear or tribocorrosion, although there are some promising leads, including markers of bone turnover.
7What design and material factors impact the wear and corrosion performance in total elbow arthroplasties?PubMed
Mark P Figgie, Timothy M Wright, Denise Drinkwater, et al.
Clin Orthop Relat Res. 2014 Dec;472(12):3770-6. doi: 10.1007/s11999-014-3781-9.
The survivorship of total elbow arthroplasties is lower than surgeons and patients would like it to be, especially in patients with posttraumatic arthritis of the elbow. To improve durability, it is important to understand the failure modes of existing implants. Total elbow arthroplasties were designed primarily for low-demand rheumatoid patients. As surgical indications have extended to more active patient populations, the mechanical performance of current designs must meet an increased mechanical burden. Evaluating the degree to which they do this will guide conclusions about which contemporary devices might still meet the need and, as importantly, what design and material changes might be needed to improve performance. WHERE ARE WE NOW?: The reasons for failures of total elbow arthroplasties include infection, loosening, polyethylene wear, locking mechanism failure, periprosthetic fracture, implant fracture, and instability. Implant design factors that have influenced wear include implant constraint, material, coatings, and metal backing. Surgical factors associated with increased wear and subsequent total elbow arthroplasty failure include soft tissue balancing and restoration of alignment and implant positioning. WHERE DO WE NEED TO GO?: A clear need exists for improving the performance of total elbow arthroplasty. Many of the failures that have limited the survivorship of elbow arthroplasties thus far are mechanical in nature with wear-related problems a dominating influence. Much of what we know about the results of total elbow arthroplasty is from small studies frequently involving the designer of the implant. The establishment of total elbow arthroplasty registries coupled with the increasing regulatory burden of postmarket surveillance would lead to a better understanding of the complications and survivorship of elbow arthroplasties. Another primary goal must be to achieve a better understanding of the biomechanics of the normal elbow and how the mechanics are altered after the insertion of elbow arthroplasty components. HOW DO WE GET THERE?: Improving the performance and survivorship of total elbow arthroplasty will require the integration of clinical and implant performance data gained through the establishment of registries with a concerted basic science effort to better understand the functional loads across the joint and to incorporate these loads into experimental and computational models to allow assessment of design and material changes intended to improve durability.
8Assessment of sheep knee joint after ACL replacement with Achilles tendon autograft and PLA-based implant.PubMed
Ewa Stodolak-Zych, Krzysztof Ficek, Jarosław Wieczorek, et al.
J Mech Behav Biomed Mater. 2022 Jan;125:104923. doi: 10.1016/j.jmbbm.2021.104923. Epub 2021 Oct 30.
In this study, we propose a new approach in the anterior cruciate ligament (ACL) replacement to provide stability and integration with bone tunnel. A polylactide (PLA)-based tubular implant was used to support the graft stabilization in femoral and tibial bones and to stimulate the healing process after (ACL) replacement on a sheep model. The ACL was replaced with an autologous Achilles tendon split graft. The tendon-to-bone healing in the model was analyzed after 6 and 12 weeks. Two groups of animals were compared, i.e. the group with the PLA-based implant used in the ACL replacement and the control group without the implant. The knee joints were mechanically and clinically evaluated, including the histopathology tests, to determine their stability and integrity. The results indicated that the bioresorbable PLA-based tubular implant may facilitate integration of the tendon graft with bone. Remodeling the allograft inside the implant improves the joint mobility from the first week of healing: no pathological changes were observed at the surgery site and in the animals' mobility. After 6 and 12 weeks of healing no significant changes in the mechanical parameters of the knee joint were observed, regarding the joint failure force, knee displacement, angular mobility range and joint stiffness. Relatively small values of the non-destructive tests in the knee displacement, already 6 weeks after surgery, indicated the early stabilization of the knee joint. The studies showed that the failure forces of knee joints after the ACL replacement with the PLA-based implant are lower than those of an intact joint, although their biomechanical features, including strain-at- failure, are similar. The biomechanical parameters of the knee joint were significantly improved due to the selected method of attaching the autograft ends to the femoral and tibial bone surfaces. After 12 weeks the intra-tunnel tendon-bone site with the PLA implant revealed the better tibia-femur joint mechanical stability, linear force-strain function and the decreasing strain-to-failure value, as compared to the control group.
9Initial fixation strength of polylactic acid interference screws in anterior cruciate ligament reconstruction.PubMed
J A Abate, P D Fadale, M J Hulstyn, et al.
Arthroscopy. 1998 Apr;14(3):278-84. doi: 10.1016/s0749-8063(98)70143-4.
The initial fixation properties of bioresorbable polylactic acid (PLA) interference screws designed for anterior cruciate ligament reconstruction were evaluated using an in vitro bovine model. The surgical technique of interference screw fixation of the bone-patellar tendon-bone autograft complex performed clinically was reproduced in an adult bovine model. The reconstructed knee was tested oriented in 30 degrees of flexion to allow examination of the femoral and tibial fixation properties simultaneously. This model examined the initial fixation strength between PLA and metal interference screws as well as a partially degraded PLA implant. Data from this in vitro model indicate that PLA interference screws can provide similar initial fixation at both time 0 and after degradation for up to 28 days compared with metal interference screws for bone-tendon-bone ACL reconstructions.
10Comparison of polylactide screw and expansion bolt in bioabsorbable fixation with patellar tendon bone graft for anterior cruciate ligament rupture of the knee. A preliminary study.PubMed
P Tuompo, E K Partio, K Jukkala-Partio, et al.
Knee Surg Sports Traumatol Arthrosc. 1999;7(5):296-302. doi: 10.1007/s001670050167.
In a preliminary study, 24 patients with rupture of the anterior cruciate ligament (ACL) were operated on using implants made of self-reinforced poly-l-lactide (SR-PLLA). The operation method was outside-in bone-tendon-bone reconstruction. In 10 patients the fixation was made with an SR-PLLA screw with a diameter of 6.3 mm, in 12 with an SR-PLLA expansion plug with a diameter of 6.0 mm, and in two cases both implants were used, but these cases were excluded from comparison. The purpose of the study was to evaluate and compare the use and fixation results of these two implants. The follow-up time averaged 3.2 years. Twenty patients attended follow-up. On subjective evaluations, seven of the eight patients following SR-PLLA screw fixation and six of the ten after expansion plug fixation regarded their knee as normal or nearly normal. Arthrometric testing showed the side-to-side difference to average 2. 9 mm following SR-PLLA screw fixation and 2.6 mm after expansion plug fixation (NS). Six of the patients had giving-way symptoms (two after screw fixation and four after plug fixation). The pivot shift test was slightly positive in two patients and positive in one patient after SR-PLLA screw fixation, and in three knees slightly positive and in another three knees positive following expansion plug fixation. Radiography showed variation in the location and orientation of the bone channels. Magnetic resonance imaging was performed in seven cases, and in two cases an edema was found in the tendon of the anterior cruciate ligament graft and in six cases the implants were visible. No statistical difference in results between the SR-PLLA screw and SR-PLLA expansion bolt was noted. Fixation with expansion plug seems technically more challenging, with a tendency to inferior results compared to screw fixation. In the absorbable fixation of a bone-tendon-bone graft there are no metallic artifacts on magnetic resonance imaging and no need to remove the fixation material regarding the revision surgery.
11Implantation of Novel Meniscus Scaffold for Irreparable Meniscal Tear.PubMed
Shuhei Otsuki, Kuniaki Ikeda, Kei Tanaka, et al.
Arthrosc Tech. 2022 Apr 22;11(5):e775-e779. doi: 10.1016/j.eats.2021.12.036. eCollection 2022 May.
Partial meniscectomy, which is generally used for the treatment of meniscal tears, can lead to knee joint osteoarthritis. To prevent this important complication, attempting to restore normal knee joint kinematics and biomechanical forces after partial meniscectomy is essential. Implantation of a meniscal scaffold can be useful in this regard, improving the function of the meniscus on knee joint biomechanics after partial meniscectomy. Use of meniscal scaffolds would have specific clinical merit for young patients who are at highest for developing knee joint osteoarthritis over time. Herein, we describe our novel bioabsorbable meniscal scaffold, fabricated with polyglycolic acid coated with polylactic acid/caprolactone, used after partial meniscectomy for degenerative and irreparable meniscal tears. The method of implantation of the scaffold will have a determinant effect on clinical outcomes. As the implementation technique by arthroscopy will be influenced by the stiffness and strength of the scaffold implant used, we provide a detailed description of our implantation technique, including a description of the pitfalls to consider in order to improve clinical outcomes.
12Research progress on biodegradable polymer-based drug delivery systems for the treatment of knee osteoarthritis.PubMed
Jinchi Zhang, Jinchao Zhang, Hailong Li, et al.
Front Bioeng Biotechnol. 2025 Apr 10;13:1561708. doi: 10.3389/fbioe.2025.1561708. eCollection 2025.
Knee osteoarthritis (KOA) is a disease that involves multiple anatomical and physiological changes in the knee tissues, including cartilage degeneration, bone remodelling and formation of bony encumbrances, which leads to clinical manifestations including pain, stiffness, swelling and limitation of knee function. Knee osteoarthritis is a chronic joint disease characterised by degenerative cartilage lesions and secondary osteophytes in the knee joint. The symptoms of knee osteoarthritis tend to progress slowly, and at this stage, the number of patients with KOA is increasing. However, due to the adverse effects and poor therapeutic outcomes following surgical treatment, intervention therapy through the utilisation of biodegradable polymeric materials is required. Currently, clinical aspects are mainly used to treat cartilage degeneration in patients with osteoarthritis of the knee by using different kinds of biodegradable biopolymer materials with excellent physical properties, histocompatibility and other properties, combined with a drug delivery system, which can reduce the level of inflammation and stiffness in the focal area, and maximise the restoration of the patient's knee joint joint mobility and athletic ability. Based on the properties of the polymeric material drug delivery system, the polymeric material has a variable drug loading capacity that encapsulates hydrophobic/hydrophilic drugs and controls the release kinetics by regulating the composition and charge. This paper reviews the research progress of Poly (ε-caprolactone) (PCL), Poly(lactic acid) (PLA), Poly (lactic glycolic acid) (PLGA), Poly(ethylene glycol) (PEG) synthetic polymers and collagen, chondroitin sulfate, other natural polymers based drug delivery systems for the treatment of knee osteoarthritis, and explains that different biodegradable polymeric materials have been widely used for the treatment of knee osteoarthritis. However, there are still issues of degradability, toxicity, compatibility, and durability and safety of the drug delivery system of degradable materials that need to be addressed in further clinical trials. As biodegradable biomedical materials continue to be explored, eventually idealized polymeric materials will stand out in the treatment of KOA.
13Manufacturing conditioned roughness and wear of biomedical oxide ceramics for all-ceramic knee implants.PubMed
Anke Turger, Jens Köhler, Berend Denkena, et al.
Biomed Eng Online. 2013 Aug 29;12:84. doi: 10.1186/1475-925X-12-84.
BACKGROUND: Ceramic materials are used in a growing proportion of hip joint prostheses due to their wear resistance and biocompatibility properties. However, ceramics have not been applied successfully in total knee joint endoprostheses to date. One reason for this is that with strict surface quality requirements, there are significant challenges with regard to machining. High-toughness bioceramics can only be machined by grinding and polishing processes. The aim of this study was to develop an automated process chain for the manufacturing of an all-ceramic knee implant. METHODS: A five-axis machining process was developed for all-ceramic implant components. These components were used in an investigation of the influence of surface conformity on wear behavior under simplified knee joint motion. RESULTS: The implant components showed considerably reduced wear compared to conventional material combinations. Contact area resulting from a variety of component surface shapes, with a variety of levels of surface conformity, greatly influenced wear rate. CONCLUSIONS: It is possible to realize an all-ceramic knee endoprosthesis device, with a precise and affordable manufacturing process. The shape accuracy of the component surfaces, as specified by the design and achieved during the manufacturing process, has a substantial influence on the wear behavior of the prosthesis. This result, if corroborated by results with a greater sample size, is likely to influence the design parameters of such devices.
14Clinical results of alumina medial pivot total knee arthroplasty at a minimum follow-up of 10years.PubMed
Suguru Nakamura, Yukihide Minoda, Shigeru Nakagawa, et al.
Knee. 2017 Mar;24(2):434-438. doi: 10.1016/j.knee.2016.12.011. Epub 2017 Feb 8.
BACKGROUND: The medial pivot total knee prosthesis with alumina ceramic femoral components was introduced to reproduce physiological knee kinematics and reduce polyethylene wear. The five-year clinical outcomes of alumina medial pivot total knee arthroplasties (TKA) have previously been reported. The purpose of this study was to provide the longer-term clinical results at a minimum follow-up of 10years. METHODS: The clinical results of 70 alumina medial pivot TKA in 51 consecutive patients, with a minimum follow-up period of 10years, were evaluated. RESULTS: Mean follow-up was 11.8years (range 10 to 13). Alumina medial pivot TKAs improved the patients' Knee Society knee scores, function scores, and postoperative ranges of motion compared with their pre-operative statuses (P<0.05 for each). Revision surgery was required in one knee due to a postoperative fracture of the tibial plateau after a fall that occurred two years postoperatively. Osteolysis and femoral component loosening was identified in one case after the initial five-year time point of analysis. The survival rate was 99.1% at 10years. CONCLUSIONS: This study demonstrated excellent clinical results for patients receiving the alumina medial pivot prosthesis at a minimum follow-up period of 10years.
15The use of compliant layer prosthetic components in orthopedic joint repair and replacement: a review.PubMed
Kenneth R St John
J Biomed Mater Res B Appl Biomater. 2014 Aug;102(6):1332-41. doi: 10.1002/jbm.b.33130. Epub 2014 Mar 5.
The surgical repair or treatment of degenerative joint disease has traditionally involved the substitution of synthetic materials for one or both surfaces of the joint. Engineering thermoplastics, metals, and ceramics have either been widely accepted or experimentally evaluated for use as bearing surfaces in these prostheses. When engineering thermoplastics are used, the opposing surface is a metal or a ceramic, but metal-on-metal, metal-on-ceramic, and ceramic-on-ceramic have also been used or tested. Researchers have sought the opportunity to utilize materials with compressive mechanical properties more closely matching those of the natural articular cartilage. This review discusses the theory, testing, and application of elastomers for one bearing component of articular joint prostheses.
16Total Articular Knee Replacement Using Polyurethane.PubMed
James W Pritchett
J Knee Surg. 2020 Mar;33(3):242-246. doi: 10.1055/s-0039-1677816. Epub 2019 Feb 4.
This study reviewed the early use of polyurethane for total knee resurfacing, the long-term results of polycarbonate urethane (PCU) for total knee replacement and conducted wear simulator testing of PCU. In 1959 and 1960, 10 patients underwent total articular polyurethane knee replacement (polyethylene was not available). The polyurethane was placed on the articular surface of the femur with metal surfaces on the tibia and patella. In 1996 and 1997, four patients received a newer PCU tibial insert in revision procedures; all had well-fixed prostheses, but no revision polyethylene implants were available. In addition, this study evaluated six new PCU tibial inserts in a 10-million cycle (Mc) wear simulator. All 10 of the early knees performed well clinically and 2 knees were functional for more than 30 years. Of the four more recent patients, all knees remain functional at more than 20 years' follow-up with no signs of wear or osteolysis. Wear simulator testing found mean material loss of 14.2 mg/Mc which equates to a volumetric wear of 11.9 mg/Mc, similar to the wear of conventional polyethylene. Polyurethane performs well as conventional polyethylene but not better than current cross-linked polyethylene tibial inserts. Its large wear particles (mean, 11 µm) and biocompatibility are less likely to cause an inflammatory response leading to pain and bone loss. Newer, superior polyurethanes can again be considered a candidate material for the tibial insert of a total knee replacement. A larger study may be able to validate polyurethane as an alternative material for joint replacement.
17The Future of TKAPubMed
William G. Blakeney, Pascal-André Vendittoli
Although total knee arthroplasty (TKA) is considered to be a cost-effective intervention, most patients do not experience natural joints, and it is reported that up to 20% of them are dissatisfied [1, 2]. A systematic review of gait analysis after TKA indicates that patients display significant kinematic differences from normal controls [3]. Due to the significant deficiencies in both our knowledge and technology in the past, we were far from replicating normal knee kinematics with TKA. These limitations in TKA function and patient satisfaction should stimulate us to restart the entire development process. Enhancements in our understanding of knee anatomy and biomechanics may suggest ways of improving TKA outcomes. Implant design needs to be advanced to reproduce the anatomy and kinematics of native knees. More precise surgical techniques with navigation, patient-matched instrumentation and robotics need to be further refined. The future of TKA is to produce more natural knee joints, with resultant improved patient satisfaction and ultimately a forgotten joint.
18Overview of the different personalized total knee arthroplasty with robotic assistance, how choosing?PubMed
Mina Wahba Morcos, David Uhuebor, Pascal-André Vendittoli
Front Surg. 2023 Mar 3;10:1120908. doi: 10.3389/fsurg.2023.1120908. eCollection 2023.
Current limitations in total knee arthroplasty (TKA) function and patient satisfaction stimulated us to question our practice. Our understanding of knee anatomy and biomechanics has evolved over recent years as we now consider that a more personalized joint reconstruction may be a better-targeted goal for TKA. Implant design and surgical techniques must be advanced to better reproduce the anatomy and kinematics of native knees and ultimately provide a forgotten joint. The availability of precision tools as robotic assistance surgery can help us recreate patient anatomy and ensure components are not implanted in a position that may compromise long-term outcomes. Robotic-assisted surgery is gaining in popularity and may be the future of orthopedic surgery. However, moving away from the concept of neutrally aligning every TKA dogma opens the door to new techniques emergence based on opinion and experience and leads to a certain amount of uncertainty among knee surgeons. Hence, it is important to clearly describe each technique and analyze their potential impacts and benefits. Personalized TKA techniques may be classified into 2 main families: unrestricted or restricted component orientation. In the restricted group, some will aim to reproduce native ligament laxity versus aiming for ligament isometry. When outside of their boundaries, all restricted techniques will induce anatomical changes. Similarly, most native knee having asymmetric ligaments laxity between compartments and within the same compartment during the arc of flexion; aiming for ligament isometry induces bony anatomy changes. In the current paper, we will summarize and discuss the impacts of the different robotic personalized alignment techniques, including kinematic alignment (KA), restricted kinematic alignment (rKA), inverse kinematic alignment (iKA), and functional alignment (FA). With every surgical technique, there are limitations and shortcomings. As our implants are still far from the native knee, it is primordial to understand the impacts and benefits of each technique. Mid to long data will help us in defining the new standards.
19Why personalized surgery is the future of hip and knee arthroplasty: a statement from the Personalized Arthroplasty Society.PubMed
Pascal-André Vendittoli, Charles Riviere, Michael T Hirschmann, et al.
EFORT Open Rev. 2023 Dec 1;8(12):874-882. doi: 10.1530/EOR-22-0096.
Although hip and knee joint replacements provide excellent clinical results, many patients still do not report the sensation and function of a natural joint. The perception that the joint is artificial may result from the anatomical modifications imposed by the surgical technique and the implant design. Moreover, the joint replacement material may not function similarly to human tissues. To restore native joint kinematics, function, and perception, three key elements play a role: (i) joint morphology (articular surface geometry, bony anatomy, etc.), (ii) lower limb anatomy (alignment, joint orientation), and (iii) soft tissue laxity/tension. To provide a 'forgotten joint' to most patients, it is becoming clear that personalizing joint replacement is the key solution. Performing a personalized joint replacement starts with patient selection and preoperative optimization, followed by using a surgical technique and implant design aimed at restoring the patient's native anatomy, creating optimal implant-to-bone stress transfer, restoring the joint's native articular range of motion without imposed limitations, macro- and micro-stability of the soft tissues, and a bearing whose wear resistance provides lifetime survivorship with unrestricted activities. In addition, the whole perioperative experience should follow enhanced recovery after surgery principles, favoring a rapid and complication-free recovery. As a new concept, some confusion may arise when applying these personalized surgery principles. Therefore, the Personalized Arthroplasty Society was created to help structure and accelerate the adoption of this paradigm change. This statement from the Society on personalized arthroplasty will serve as a reference that will evolve with time.
20Patient-Specific Orthopaedic Implants.PubMed
Jack M Haglin, Adam E M Eltorai, Joseph A Gil, et al.
Orthop Surg. 2016 Nov;8(4):417-424. doi: 10.1111/os.12282.
Patient-specific orthopaedic implants are emerging as a clinically promising treatment option for a growing number of conditions to better match an individual's anatomy. Patient-specific implant (PSI) technology aims to reduce overall procedural costs, minimize surgical time, and maximize patient outcomes by achieving better biomechanical implant fit. With this commercially-available technology, computed tomography or magnetic resonance images can be used in conjunction with specialized computer programs to create preoperative patient-specific surgical plans and to develop custom cutting guides from 3-D reconstructed images of patient anatomy. Surgeons can then place these temporary guides or "jigs" during the procedure, allowing them to better recreate the exact resections of the computer-generated surgical plan. Over the past decade, patient-specific implants have seen increased use in orthopaedics and they have been widely indicated in total knee arthroplasty, total hip arthroplasty, and corrective osteotomies. Patient-specific implants have also been explored for use in total shoulder arthroplasty and spinal surgery. Despite their increasing popularity, significant support for PSI use in orthopaedics has been lacking in the literature and it is currently uncertain whether the theoretical biomechanical advantages of patient-specific orthopaedic implants carry true advantages in surgical outcomes when compared to standard procedures. The purpose of this review was to assess the current status of patient-specific orthopaedic implants, to explore their future direction, and to summarize any comparative published studies that measure definitive surgical characteristics of patient-specific orthopaedic implant use such as patient outcomes, biomechanical implant alignment, surgical cost, patient blood loss, or patient recovery.
21[Total and unicompartmental knee replacement. Patient-specific Instrumentation].PubMed
G Köster, C Biró
Orthopade. 2016 Apr;45(4):302-13. doi: 10.1007/s00132-016-3245-x.
BACKGROUND: The objective of patient-specific instrumentation (PSI Zimmer®) technology is to optimize positioning and selection of components as well as surgical procedure in uni- and bicompartimental knee replacement. The article contains a description of the planning and surgical technique and evaluates the method based on own results and literature. METHODS: Using MRI or CT scans a virtual 3D model of the joint is created in order to simulate and plan the implant positioning. According to these data, pin placement and/or cutting guides are produced, which enable the surgeon to transfer the planning to the surgical procedure. In a prospective comparative study 88 patients (44 per each of the two techniques) were operated by one surgeon receiving the same TKA using either MRI-based PSI or a conventional technique. The number of surgical trays, operating time, intraoperative changes and frontal alignment using a full leg x‑ray (70 cases) were compared. In 17 patients the method was applied with unicondylar knee replacement. RESULTS: Anatomical abnormalities could be detected preoperatively and considered during the operation. With PSI the number of trays could be reduced and predictability of the component size was more precise. Intraoperative changes became necessary only for distal femoral (25 %) and proximal tibial (36 %) resection and tibial rotation (40 %). Alignment was more precise in the PSI cases DISCUSSION: PSI using the applied technique proved to be practicable and reliable. The advantages of precise planning became obvious. Results concerning alignment are inconsistent in the literature. Soft tissue balancing has only been included in the technique to a limited degree so far. PSI is still in an early stage of development and further development opportunities should be exploited before final assessment.
22Evaluation of Patellar Groove Prostheses in Veterinary Medicine: Review of Technological Advances, Technical Aspects, and Quality Standards.PubMed
Mateusz Pawlik, Piotr Trębacz, Anna Barteczko, et al.
Materials (Basel). 2025 Apr 3;18(7):1652. doi: 10.3390/ma18071652.
This review explores the technological advancements in, engineering considerations regarding, and quality standards of veterinary patellar groove replacement implants. Veterinary-specific regulations for these implants are currently lacking. Therefore, human knee implant benchmarks are used as references. These benchmarks guide evaluation of the surface quality, material selection, biocompatibility, and mechanical performance of the implant to ensure reliability and longevity. Patellar luxation is a common orthopedic disorder in small animals which leads to patellofemoral joint instability and cartilage degeneration, and is often caused by angular limb deformities that disrupt patellar alignment. In severe cases, patellar groove replacement is necessary to restore function and alleviate pain. The implant materials must provide durability, mechanical strength, and biocompatibility to withstand joint forces while ensuring minimal wear. High-quality surface finishes reduce the friction experienced by these materials, improving their long-term performance. Advances in 3D printing allow the creation of patient-specific implants. These implants offer an enhanced anatomical fit and enhanced functionality, which is especially beneficial in complex cases. However, challenges remain in achieving consistent manufacturing quality and economic feasibility. While custom implants are invaluable for difficult cases, standardized designs are sufficient for routine applications. Combining human implant standards with new manufacturing technologies improves veterinary orthopedic solutions. This integration expands the treatment options for patellar luxation and enhances the quality and accessibility of implants.
23[Patient-specific instrumentation in total knee arthroplasty - current concepts and clinical implications].PubMed
Ricarda Stauss, Peter Savov, Hendrik Pott, et al.
Orthopadie (Heidelb). 2025 Sep;54(9):675-681. doi: 10.1007/s00132-025-04689-6. Epub 2025 Jul 22.
BACKGROUND: In total knee arthroplasty (TKA), there is a trend towards personalized concepts, and the implementation of innovative technologies is crucial for the precise execution of modern alignment strategies. PATIENT-SPECIFIC INSTRUMENTATION: Patient-specific instrumentation (PSI) enables a detailed preoperative analysis of the patient's bony anatomy, and optimal component placement is determined in the virtual implant planning stage. PSI-guided execution of the surgical plan enables an improved precision and reproducibility of the surgical results. Despite the use of 3D-printed cutting guide instruments in standard TKA cases, PSI is increasingly being used in surgically complex cases that require an individualized surgical plan. CURRENT SITUATION OF STUDIES: With the increasing utilization of modern technologies in TKA and the expansion of the indications for PSI-TKA to complex cases, a thorough understanding of the potential benefits and limitations of this technology is crucial to determine the cases that will benefit most from the procedure. Therefore, the purpose of this article is to provide an overview on the current evidence and clinical implications of PSI-guided TKA.
24Computational analysis of customized cruciate retaining total knee arthroplasty restoration of native knee joint biomechanics.PubMed
Yong-Gon Koh, Jin-Ah Lee, Pill Ku Chung, et al.
Artif Organs. 2019 May;43(5):504-514. doi: 10.1111/aor.13382. Epub 2018 Dec 12.
The purpose of this study was to verify if customized prosthesis better preserves the native knee joint kinematics and provides lower contact stress on the polyethylene (PE) insert owing to the wider bone preservation than that of standard off-the-shelf prosthesis in posterior cruciate-retaining type total knee arthroplasty (TKA). Validated finite element (FE) models for were developed to evaluate the knee joint kinematics and contact stress on the PE insert after TKA with customized and standard off-the-shelf (OTS) prostheses as well as in normal healthy knee through FE analysis under dynamic loading conditions. The contact stresses on the customized prosthesis decreased by 18% and 8% under gait cycle loading conditions, and 24% and 9% under deep-knee-bend loading conditions, in the medial and lateral sides of the PE insert, respectively, compared with the standard OTS prosthesis. The anterior-posterior translation and internal-external (IE) rotation in customized TKA were more similar to native knee joint behaviors compared with standard OTS TKA under gait loading conditions. The difference from normal knee kinematics was lower for femoral rollback and IE rotation in customized TKA than in standard OTS TKA in the deep-knee-bend condition. In general, customized prostheses achieve kinematics that are close to those of the native healthy knee joint and have better contact stresses than standard OTS prostheses in gait and deep-knee-bend loading conditions.
25‘À La Carte’ Joint ReplacementPubMed
Charles Rivière, Ciara Harman, Kartik Logishetty
Hip and knee arthroplasties are life-changing procedures, reducing pain and restoring function after end-stage arthrosis. Almost 90% of patients who have undergone hip arthroplasty, and 82% after knee arthroplasty, report improvement in quality of life after surgery [1]; this leaves a significant number of dissatisfied patients. The modern surgeon can make decisions regarding surgical approach, implant design and component orientation. However, it is challenging to gain proficiency in a wide variety of surgical configurations. A smaller repertoire is technically and economically more feasible, and thus a one-size-fits-all approach is commonplace. Hip and knee arthroplasties are forgiving procedures, most frequently performed in older patients without high functional demands. The future arthroplasty surgeon is faced with new challenges—patients with higher demand, expectations and longer life expectancy, in addition to an increasing burden of revision surgery. Here, we discuss ‘a la carte’ joint replacement, which is both patient specific and bone/soft tissue conservative. It may improve overall satisfaction while conserving bone stock in the event of future revision surgery.
26Gait analysis of patients with an off-the-shelf total knee replacement versus customized bi-compartmental knee replacement.PubMed
Henry Wang, Jonathan Foster, Natasha Franksen, et al.
Int Orthop. 2018 Apr;42(4):805-810. doi: 10.1007/s00264-017-3622-z. Epub 2017 Sep 4.
INTRODUCTION: Newer TKR designs have been introduced to the market with the aim of overcoming common sizing problems with older TKR designs. Furthermore, since a sizable percentage of patients with OA present with disease limited to the medial/lateral knee compartment in addition to the patellofemoral joint, for whom, a customized bi-compartmental knee replacement (BKR) is available as a treatment option. To date, there is very little information regarding knee strength and mechanics during gait for patients implanted with these modern TKR and BKR designs. The purpose of the study was to evaluate knee strength and mechanics during walking for patients with either a modern off the shelf TKR or a customized BKR and compare these findings to a cohort of healthy controls. METHODS: Twelve healthy controls, eight BKR, and nine TKR patients participated in the study. Maximal isometric knee strength was evaluated. 3D kinematic and kinetic analyses were conducted for level walking. RESULTS: The TKR knee exhibited less peak extensor torque when compared to, both the BKR and control limbs (p < 0.05). The TKR knee had less extensor moment at stance than both the BKR and control knees (p < 0.05). Both the BKR and control knees displayed larger internal rotation at stance than that of the TKR knee (p < 0.05). DISCUSSION AND CONCLUSION: This study suggests that, for patients that exhibit isolated OA of the tibiofemoral joint, using a customized BKR implant is a viable treatment option and may contribute to superior mechanical advantages.
27Individualized total knee arthroplasty achieves better functional results than off-the-shelf implants in patients undergoing personalized coronal alignment.PubMed
Bernard de Geofroy, Tristan Fauchille, Michael Djian, et al.
Knee. 2025 Mar;53:228-235. doi: 10.1016/j.knee.2024.12.009. Epub 2025 Jan 25.
BACKGROUND: Several studies have demonstrated the interest in patient-specific custom cutting guides in total knee arthroplasty (TKA), but clinical improvement remains debated. The purpose of this study was to evaluate the functional outcomes (Forgotten Joint Score, FJS) of patients undergoing individualized TKA compared with those receiving off-the-shelf (OTS) implants, both using patient-specific cutting guides with personalized alignment over a minimum follow up period of 12 months. We hypothesized that individualized TKA demonstrates significantly better functional outcomes than OTS TKA (FJS and percentage of patients reaching the minimum clinically important difference). METHODS: A continuous single-surgeon retrospective series was analyzed from September 2018 to June 2020. The inclusion criterion was primary TKA for osteoarthritis. The series compared 58 individualized TKAs to 54 standard implants, with personalized alignment, at a mean follow up of 25 (12-40) months. The two groups were comparable in gender, age, BMI, and preoperative deformity. Complications and revision procedures were recorded. The FJS, New IKS, and Oxford Knee Score were assessed at the last follow up, and the sensation of a forgotten knee was evaluated. RESULTS: One patient in each group required TKA revision. At last follow up, the individualized TKA group showed significantly better FJS (91 ± 14 vs. 81 ± 23, P = 0.01), satisfaction category in the IKS (36 ± 5 vs. 32 ± 8, P = 0.002), IKS function (83 ± 11 vs. 72 ± 21, P = 0.003) and Oxford scores (44 ± 5 vs. 39 ± 10, P = 0.005. There was no significant difference in the IKS objective score (88 ± 16 vs. 82 ± 2, P = 0.34). The sensation of a forgotten knee rate did not differ significantly between the groups. CONCLUSION: Individualized TKA leads to improved clinical outcomes significantly compared with OTS TKA, utilizing personalized alignment and patient-specific cutting guides. This combination of personalized factors and individualized TKA enhances the potential to tackle the challenges associated with TKA and improve functional results.
28Individualized reconstruction for severe periprosthetic fractures around the tumor prosthesis of knee under assistance of 3D printing technology: A case report.PubMed
Qing Han, Xue Zhao, Chenyu Wang, et al.
Medicine (Baltimore). 2018 Oct;97(42):e12726. doi: 10.1097/MD.0000000000012726.
INTRODUCTION: Periprosthetic femoral fractures (PFF) around tumor prosthesis of knee are stubborn problems for surgeons, huge bone defect and inappropriate biomechanics of the revision implant design can be disaster for reconstruction. With the development of three-dimensional (3D) printing technology, surgeons participate more in precise preoperative design and simulation for treatment of such fractures. In this study we explored an accurate and feasible way to restore normal anatomy and function of the knee joint with 3D printing technology. CASE PRESENTATION: Rationale: This report explored an accurate and feasible way to treat PFF around tumor knee prosthesis in a 32 years old women with 3D printing technology, which restored normal anatomy and function of the knee joint. Patient concerns: Pain in left thigh lasted for 10 months after resection of left femoral chondroma and knee joint replacement four years ago. Diagnoses: periprosthetic femoral fractures (PFF) around tumor knee prosthesis. INTERVENTIONS: CT images of the patient were collected and reconstructed. Parameters of bilateral femurs were virtually sliced and measured. Novel femoral stem and nail paths were specially designed by doctors according to these parameters. The prosthetic femoral stem components and navigator were customized by engineers according to the doctor's design. The residual femoral resin model, customized components and navigator were printed with Stereo Lithography Apparatus 3D printer. The shape-preconcerted allograft bone was selected as patch for the bone defect before operation with the printed bone model. All the steps were simulated preoperatively with the models printed, and then the operation was carried out. OUTCOMES: The operation was successfully performed. The postoperative x-ray image, MSTS93 scores were examined and the function restoration sustained well in the follow-up period from 1 month to 27 months. LESSONS: 3D printing and medical interaction are key points in complex PFF cases. CONCLUSION: As for PFF of the complex tumor of knee, preoperative design and simulation with 3D printing technology may provide more accurate and effective operative outcome than traditional methods, which might be considered as a method suitable for popularization in complex and severe cases.
29Current concepts in total knee arthroplasty : mechanical, kinematic, anatomical, and functional alignment.PubMed
Fahima A Begum, Babar Kayani, Ahmed A Magan, et al.
Bone Jt Open. 2021 Jun;2(6):397-404. doi: 10.1302/2633-1462.26.BJO-2020-0162.R1.
Limb alignment in total knee arthroplasty (TKA) influences periarticular soft-tissue tension, biomechanics through knee flexion, and implant survival. Despite this, there is no uniform consensus on the optimal alignment technique for TKA. Neutral mechanical alignment facilitates knee flexion and symmetrical component wear but forces the limb into an unnatural position that alters native knee kinematics through the arc of knee flexion. Kinematic alignment aims to restore native limb alignment, but the safe ranges with this technique remain uncertain and the effects of this alignment technique on component survivorship remain unknown. Anatomical alignment aims to restore predisease limb alignment and knee geometry, but existing studies using this technique are based on cadaveric specimens or clinical trials with limited follow-up times. Functional alignment aims to restore the native plane and obliquity of the joint by manipulating implant positioning while limiting soft tissue releases, but the results of high-quality studies with long-term outcomes are still awaited. The drawbacks of existing studies on alignment include the use of surgical techniques with limited accuracy and reproducibility of achieving the planned alignment, poor correlation of intraoperative data to long-term functional outcomes and implant survivorship, and a paucity of studies on the safe ranges of limb alignment. Further studies on alignment in TKA should use surgical adjuncts (e.g. robotic technology) to help execute the planned alignment with improved accuracy, include intraoperative assessments of knee biomechanics and periarticular soft-tissue tension, and correlate alignment to long-term functional outcomes and survivorship.
30Alignment Techniques in Total Knee Arthroplasty: Where do We Stand Today?PubMed
Hemanta Dhungana, Subhash Jangid, Meghal Goyal
Chin Med Sci J. 2024 Sep 30;39(3):217-225. doi: 10.24920/004372.
Achieving optimal alignment in total knee arthroplasty (TKA) is a critical factor in ensuring optimal outcomes and long-term implant survival. Traditionally, mechanical alignment has been favored to achieve neutral post-operative joint alignment. However, contemporary approaches, such as kinematic alignments and hybrid techniques including adjusted mechanical, restricted kinematic, inverse kinematic, and functional alignments, are gaining attention for their ability to restore native joint kinematics and anatomical alignment, potentially leading to enhanced functional outcomes and greater patient satisfaction. The ongoing debate on optimal alignment strategies considers the following factors: long-term implant durability, functional improvement, and resolution of individual anatomical variations. Furthermore, advancements of computer-navigated and robotic-assisted surgery have augmented the precision in implant positioning and objective measurements of soft tissue balance. Despite ongoing debates on balancing implant longevity and functional outcomes, there is an increasing advocacy for personalized alignment strategies that are tailored to individual anatomical variations. This review evaluates the spectrum of various alignment techniques in TKA, including mechanical alignment, patient-specific kinematic approaches, and emerging hybrid methods. Each technique is scrutinized based on its fundamental principles, procedural techniques, inherent advantages, and potential limitations, while identifying significant clinical gaps that underscore the need for further investigation.
31[Research progress of functional alignment robot assisted knee replacement].PubMed
Yong-Ze Yang, Qing-Hao Cheng, An-Ren Zhang, et al.
Zhongguo Gu Shang. 2023 Nov 25;36(11):1106-10. doi: 10.12200/j.issn.1003-0034.2023.11.019.
The correct alignment of the knee joint is considered to be one of the most influential factors in determining the long-term prognosis after total knee arthroplasty(TKA). In order to achieve the correct alignment goal, many different alignment concepts and surgical techniques have been established. For example, mechanical alignment(MA), kinematic alignment(KA) and functional alignment(FA) have their own characteristics. MA focuses on achieving neutral alignment of the limbs, parallel and equal bone gaps during stretching and flexion. KA aims to restore the patient 's natural joint line, make the joint level and angle normal and improve the physiological soft tissue balance, and strive to reproduce the normal knee function;among them, functional alignment(FA) developed with robot-assisted surgery technology is a relatively new alignment concept. It not only considers the alignment of the body, but also aims to achieve flexion and extension balance, while respecting the native soft tissue capsule. It not only restores the plane and slope of the in situ joint line accurately during the operation, but also takes into account the balance of soft tissue, which is a better alignment method. Therefore, it is of great significance to correctly construct the lower limb force line of patients, which is helpful to restore knee joint function, relieve pain symptoms and prolong the service life of prosthesi. However, compared with traditional TKA, the operation time of robot-assisted FA-TKA is prolonged, which means that the probability of postoperative infection will be greater. At present, most studies of FA technology report short-term results, and the long-term efficacy of patients is not clear. Therefore, long-term research results are needed to support the application of this technology. Therefore, the author makes a review on the research status of functional alignment.
32Functional alignment achieves soft-tissue balance in total knee arthroplasty as measured with quantitative sensor-guided technology.PubMed
Justin S Chang, Babar Kayani, Charles Wallace, et al.
Bone Joint J. 2021 Mar;103-B(3):507-514. doi: 10.1302/0301-620X.103B.BJJ-2020-0940.R1. Epub 2021 Jan 20.
AIMS: Total knee arthroplasty (TKA) using functional alignment aims to implant the components with minimal compromise of the soft-tissue envelope by restoring the plane and obliquity of the non-arthritic joint. The objective of this study was to determine the effect of TKA with functional alignment on mediolateral soft-tissue balance as assessed using intraoperative sensor-guided technology. METHODS: This prospective study included 30 consecutive patients undergoing robotic-assisted TKA using the Stryker PS Triathlon implant with functional alignment. Intraoperative soft-tissue balance was assessed using sensor-guided technology after definitive component implantation; soft-tissue balance was defined as intercompartmental pressure difference (ICPD) of < 15 psi. Medial and lateral compartment pressures were recorded at 10°, 45°, and 90° of knee flexion. This study included 18 females (60%) and 12 males (40%) with a mean age of 65.2 years (SD 9.3). Mean preoperative hip-knee-ankle deformity was 6.3° varus (SD 2.7°). RESULTS: TKA with functional alignment achieved balanced medial and lateral compartment pressures at 10° (25.0 psi (SD 6.1) vs 23.1 psi (SD 6.7), respectively; p = 0.140), 45° (21.4 psi (SD 5.9) vs 20.6 psi (SD 5.9), respectively; p = 0.510), and 90° (21.2 psi (SD 7.1) vs 21.6 psi (SD 9.0), respectively; p = 0.800) of knee flexion. Mean ICPD was 6.1 psi (SD 4.5; 0 to 14) at 10°, 5.4 psi (SD 3.9; 0 to 12) at 45°, and 4.9 psi (SD 4.45; 0 to 15) at 90° of knee flexion. Mean postoperative limb alignment was 2.2° varus (SD 1.0°). CONCLUSION: TKA using the functional alignment achieves balanced mediolateral soft-tissue tension through the arc of knee flexion as assessed using intraoperative pressure-sensor technology. Further clinical trials are required to determine if TKA with functional alignment translates to improvements in patient satisfaction and outcomes compared to conventional alignment techniques. Cite this article: 2021;103-B(3):507-514.
33Functional alignment in total knee arthroplasty is an umbrella term-A call for better definition and reporting quality!PubMed
Antonio Klasan, Dragan Jeremic, Thomas Neri, et al.
Knee Surg Sports Traumatol Arthrosc. 2025 Jul 13. doi: 10.1002/ksa.12774.
PURPOSE: Functional alignment (FA) aims to achieve a symmetric, rectangular extension gap and a rectangular or trapezoidal flexion gap, positioning the components in a manner that reduces the compromises to the soft tissue envelope. Because the FA surgeon can accomplish this goal with a multitude of adjustments to the components' position or soft tissue balance, the purpose of the present study was to analyze the possible paths for achieving FA. METHODS: Ten knees undergoing robotic total knee arthroplasty (TKA) were analyzed. Based on the intraoperatively acquired data, a macro was created to perform a post hoc analysis of the 10 possible paths to align a TKA functionally: (1) starting from mechanical alignment (MA) or kinematic alignment (KA), (2) preserving either the position of the femoral or tibial component and (3) with equal, 1 mm gaps or with increased 90° lateral flexion laxity. RESULTS: Ten different knee phenotypes were analyzed (Var-Neu-Neu 2x; Neu-Neu-Val; Val-Val-Val; Neu-Val-Neu; Var-Neu-Var 3x; Var-Var-Var; Var-Var-Val). On average, 3.5 different paths resulted in FA for each TKA (range: 0-8). Two TKAs (Val-Val-Val; Var-Var-Val) could not be functionally aligned using any of the ten evaluated paths. One TKA could be functionally aligned using eight different paths. CONCLUSION: Functionally aligning a TKA can be achieved through multiple adjustments, resulting in various implant positions and soft tissue balances. To better understand the different combinations behind FA, a more detailed nomenclature is needed, including which initial alignment (MA or KA) was utilized, which component's position (femoral or tibial) was preserved, and whether a rectangular or trapezoidal flexion space was targeted. LEVEL OF EVIDENCE: Level IV, therapeutic study.
34The John N. Insall Award: Functional Versus Mechanical Alignment in Total Knee Arthroplasty: A Randomized Controlled Trial.PubMed
Simon W Young, Mei Lin Tay, Kohei Kawaguchi, et al.
J Arthroplasty. 2025 Jul;40(7S1):S20-S30.e2. doi: 10.1016/j.arth.2025.02.065. Epub 2025 Feb 27.
BACKGROUND: Mechanical alignment (MA) in total knee arthroplasty is regarded as a gold standard; however, some patients report dissatisfaction postsurgery. Functional alignment (FA) is a potential alternative, integrating kinematic alignment (KA) principles with preresection bone balancing within defined boundaries. The use of FA aims to improve outcomes by restoring native joint lines and optimizing soft-tissue balance. However, comparative evidence is limited. METHODS: This prospective, randomized controlled trial compared MA (n = 121) and FA (n = 123) in robotic-assisted total knee arthroplasty. For MA, components were positioned perpendicular to the limb mechanical axis, with soft-tissue releases to achieve balance. For FA, initial virtual component positioning was used to match native knee anatomy, with adjustments for soft-tissue balance before bone cuts. The primary outcome was the forgotten joint score (FJS). Outcomes were compared with a mixed-model analysis of variance. RESULTS: At the 2-year follow-up, the mean FJS was comparable (MA: 64.4 ± 30.1 versus FA: 70.1 ± 25.6, P = 0.10). The MA cases had more soft-tissue releases than FA (65 versus 16%, P < 0.001). Compared to MA patients, FA patients had higher Knee Injury and Osteoarthritis Outcome (KOOS) Symptoms (86.6 ± 12.9 versus 82.5 ± 14.0, P = 0.01) and KOOS-Quality of Life scores (76.1 ± 20.3 versus 70.7 ± 22.7, P = 0.03). More FA patients "would recommend" the procedure (94 versus 82%, P < 0.01). For patients who had preoperative Coronal Plane Alignment of the Knee Type I, FA had higher FJS (71.3 ± 24.8 versus 56.8 ± 31.6, P = 0.02) and KOOS-Quality of Life (76.4 ± 21.7 versus 64.2 ± 19.2, P = 0.02) than MA. No other differences were seen in patient-reported outcomes (Oxford Knee Score, KOOS, EuroQol-5 Dimensions, Pain Visual Analog Scale), clinical outcomes (length of stay, functional physio tests), reoperations, or implant survivorship (FA: 1 versus MA: 0 revisions). CONCLUSIONS: While FA required fewer soft-tissue releases compared to mechanical alignment, at 2 years patient-reported and clinical outcomes were similar. The use of FA may provide improved outcomes for a specific subgroup of patients based on their preoperative alignment.
35Functional alignment restores native kinematics more consistently than mechanical axis alignment in total knee arthroplasty.PubMed
Jonathan R Manara, Rick Steer, Sarah L Whitehouse, et al.
Bone Joint J. 2025 Apr 1;107-B(4):423-431. doi: 10.1302/0301-620X.107B4.BJJ-2024-0956.R1.
AIMS: Functional alignment (FA) and adjusted mechanical alignment (aMA) are recognized techniques for performing total knee arthroplasty (TKA). The native femur rolls back further on the lateral tibial plateau than the medial side during flexion, resulting in a medial pivot pattern of movement. We have assessed whether an individualized alignment technique affects the kinematic pattern observed and the clinical outcomes, when compared to a systematic alignment technique in TKA. METHODS: A total of 60 consecutive patients were randomized to a robotically assisted TKA with either FA (n = 29) or aMA (n = 31), using a cruciate-retaining (CR) implant. After definitive implantation of the prostheses, a trial pressure monitor was inserted recording contact points between the femoral component and monitor in the medial and lateral compartments as the knee was taken through a range of motion. The kinematic pattern was observed, contact pressures measured, and patient-reported outcome measures (PROMs) assessed at 12 months. RESULTS: The FA-TKA group produced a medial pivot in 58.6% of cases (17/29), symmetrical rollback in 37.9% (11/29), and a lateral pivot in 3.4% (1/29). The aMA-TKA group produced a medial pivot in 19.4% of cases (6/31), symmetrical rollback in 45.2% (14/31), and a lateral pivot in 35.5% (11/31) (p < 0.001). No differences in knee balance were recorded between the two alignment groups at any flexion point. Patients with a medial pivot kinematic pattern had superior one-year PROMs in some measures. Patients producing a lateral pivot had lower Kujala scores. CONCLUSION: FA CR-TKA generates an intraoperative medial pivot kinematic pattern through soft-tissue balance more often than those that use aMA. Lateral pivot kinematic patterns are more commonly found with aMA. These intraoperative kinematic patterns are related to clinical outcomes, with knees producing a medial pivot performing better than those with lateral pivot.
36Anterior cruciate ligament fixation: is radial force a predictor of the pullout strength of soft-tissue interference devices?PubMed
Kathryn E Smith, Mateo Garcia, Kadija McAnuff, et al.
Knee. 2012 Dec;19(6):786-92. doi: 10.1016/j.knee.2012.02.008. Epub 2012 Mar 21.
BACKGROUND: In anterior cruciate ligament (ACL) reconstruction, an interference device achieves soft-tissue graft fixation by radially compressing the graft against the bone. PURPOSE: The objective of this study was to measure the radial force generated by different interference devices and evaluate the effect of this radial force on the pullout strength of graft-device constructs. STUDY DESIGN: Controlled laboratory study. METHODS: A resultant force (F(R)) was used as a representative measure of the total radial force generated. Bovine tendons were fixated in either synthetic bone or porcine tibia using one of following devices: (1) RCI titanium screw, (2) PEEK screw, (3) IntraFix sheath-and-screw device, and (4) ExoShape sheath-and-insert device. F(R) was measured while each device was inserted into synthetic bone mounted on a test machine (n=5 for each device). In a subsequent test series, graft-device constructs were loaded to failure at 50mm/min. The pullout strength was measured as the ultimate load before failure (n=10 for each device). RESULTS: The F(R) values generated during insertion into synthetic bone were 777 ± 86N, 865 ± 140N, 1313 ± 198N, and 1780 ± 255N for the RCI screw, PEEK screw, IntraFix, and ExoShape, respectively. The pullout strengths in synthetic bone for the RCI screw, PEEK screw, IntraFix and ExoShape were 883 ± 125N, 716 ± 249N, 1147 ± 142N, and 1233 ± 190N, respectively. CONCLUSIONS: These results suggest that the F(R) generated during interference fixation affects the pullout strength with sheath-based devices providing superior F(R) compared with interference screws. The use of synthetic bone was validated by comparing the pullout strengths to those when tested in porcine tibia. CLINICAL RELEVANCE: These results could be valuable to a surgeon when determining the best fixation device to use in the clinical setting.
37Embossing of a screw thread and TCP granules enhances the fixation strength of compressed ACL grafts with interference screws.PubMed
Mazda Farshad, Robert A Weinert-Aplin, Michael Stalder, et al.
Knee Surg Sports Traumatol Arthrosc. 2012 Feb;20(2):268-74. doi: 10.1007/s00167-011-1623-9. Epub 2011 Jul 21.
PURPOSE: Fixation of soft tissue grafts with interference screws relies on the friction of the graft between the screw and the bone tunnel. The goal of this study was to precondition such grafts by mechanical compression in order to reduce anticipated and undesired viscoelastic adaptation of the graft to screw pressure. Further, the otherwise slippery graft surface was modified with impressed tricalcium phosphate granules (TCP) to improve friction and mechanical hold. METHODS: Fresh flexor digitorum tendons from young bovines were used to create bundles with a diameter of 8-9 mm and were divided into 10 groups to compare the pullout strength and bone damage in a variety of construct scenarios. Specifically, the effects of graft precompression to reduce preimplantation graft diameter were investigated. Further the effects of impressing TCP granules and/or a screw thread into the tendon surface during the compression process were studied. RESULTS: In sawbone tests, radial graft compression allowed for a smaller bone tunnel (7 mm), but resulted in a significantly lower pullout strength of 174 N (95% CI: 97, 250), compared with controls [315 N (204, 426)]. In contrast, TCP coated [402 N (243, 561)], screw embossed grafts [458 N (302, 614)], and the combination of TCP and embossing [409 N (274, 543)] achieved higher pullout strengths when compared to the standard technique. In porcine bone, untreated grafts using an 8 mm screw pulled out at 694 ± 93 N, significantly higher loads were required to pullout compressed grafts with or without TCP coating (870 ± 74 and 878 ± 131 N), yet fixed with a 7 mm screw. CONCLUSION: Modification of the tendon graft surface has a large influence on the biomechanical performance of interference screw fixation and results in less bone damage inflicted during insertion to a smaller tunnel diameter, while simultaneously achieving superior pullout strength.
38Influence of post-cam design of posterior stabilized knee prosthesis on tibiofemoral motion during high knee flexion.PubMed
Kun-Jhih Lin, Chang-Hung Huang, Yu-Liang Liu, et al.
Clin Biomech (Bristol). 2011 Oct;26(8):847-52. doi: 10.1016/j.clinbiomech.2011.04.002. Epub 2011 May 5.
BACKGROUNDS: The post-cam design of contemporary posterior stabilized knee prosthesis can be categorized into flat-on-flat or curve-on-curve contact surfaces. The curve-on-curve design has been demonstrated its advantage of reducing stress concentration when the knee sustained an anteroposterior force with tibial rotation. How the post-cam design affects knee kinematics is still unknown, particularly, to compare the difference between the two design features. Analyzing knee kinematics of posterior stabilized knee prosthesis with various post-cam designs should provide certain instructions to the modification of prosthesis design. METHODS: A dynamic knee model was utilized to investigate tibiofemoral motion of various post-cam designs during high knee flexion. Two posterior stabilized knee models were constructed with flat-on-flat and curve-on-curve contact surfaces of post-cam. Dynamic data of axial tibial rotation and femoral translation were measured from full-extension to 135°. FINDINGS: Internal tibial rotation increased with knee flexion in both designs. Before post-cam engagement, the magnitude of internal tibial rotation was close in the two designs. However, tibial rotation angle decreased beyond femoral cam engaged with tibial post. The rate of reduction of tibial rotation was relatively lower in the curve-on-curve design. From post-cam engagement to extreme flexion, the curve-on-curve design had greater internal tibial rotation. INTERPRETATION: Motion constraint was generated by medial impingement of femoral cam on tibial post. It would interfere with the axial motion of the femur relative to the tibia, resulting in decrease of internal tibial rotation. Elimination of rotational constraint should be necessary for achieving better tibial rotation during high knee flexion.
39Robotic Total Knee Arthroplasty: Surgical Assistant for a Customized Normal Kinematic Knee.PubMed
Kenneth L Urish, Michael Conditt, Martin Roche, et al.
Orthopedics. 2016 Sep 1;39(5):e822-7. doi: 10.3928/01477447-20160623-13. Epub 2016 Jul 12.
Although current total knee arthroplasty (TKA) is considered a highly successful surgical procedure, patients undergoing TKA can still experience substantial functional impairment and increased revision rates as compared with those undergoing total hip arthroplasty. Robotic-assisted surgery has been available clinically for almost 15 years and was developed, in part, to address these concerns. Robotic-assisted surgery aims to improve TKA by enhancing the surgeon's ability to optimize soft tissue balancing, reproduce alignment, and restore normal knee kinematics. Current systems include a robotic arm with a variety of different navigation systems with active, semi-active, or passive control. Semi-active systems have become the dominant strategy, providing a haptic window through which the surgeon consistently prepares a TKA based on preoperative planning. A review of previous designs and clinical studies demonstrates that these robotic systems decrease variability and increase precision, primarily with the mechanical axis and restoration of the joint line. Future design objectives include precise planning and consistent intraoperative execution. Preoperative planning, intraoperative sensors, augmenting surgical instrumentation, and biomimetic surfaces will be used to re-create the 4-bar linkage system in the knee. Implants will be placed so that the knee functions with a medial pivot, lateral rollback, screw home mechanism, and patellar femoral tracking. Soft tissue balancing will become more than equalizing the flexion and extension gaps and will match the kinematics to a normal knee. Together, coupled with advanced knee designs, they may be the key to a patient stating, "My knee feels like my natural knee." [Orthopedics. 2016; 39(5):e822-e827.].
40Robotic-arm assisted total knee arthroplasty is associated with improved accuracy and patient reported outcomes: a systematic review and meta-analysis.PubMed
Junren Zhang, Wofhatwa Solomon Ndou, Nathan Ng, et al.
Knee Surg Sports Traumatol Arthrosc. 2022 Aug;30(8):2677-2695. doi: 10.1007/s00167-021-06464-4. Epub 2021 Feb 6.
This systematic review and meta-analysis were conducted to compare the accuracy of component positioning, alignment and balancing techniques employed, patient-reported outcomes, and complications of robotic-arm assisted total knee arthroplasty (RATKA) with manual TKA (mTKA) and the associated learning curve. Searches of PubMed, Medline and Google Scholar were performed in October 2020 using PRISMA guidelines. Search terms included "robotic", "knee" and "arthroplasty". The criteria for inclusion were published clinical research articles reporting the learning curve for RATKA and those comparing the component position accuracy, alignment and balancing techniques, functional outcomes, or complications with mTKA. There were 198 articles identified, following full text screening, 16 studies satisfied the inclusion criteria and reported the learning curve of rTKA (n=5), component positioning accuracy (n=6), alignment and balancing techniques (n=7), functional outcomes (n=7), or complications (n=5). Two studies reported the learning curve using CUSUM analysis to establish an inflexion point for proficiency which ranged from 7 to 11 cases and there was no learning curve for component positioning accuracy. The meta-analysis showed a significantly lower difference between planned component position and implanted component position, and the spread was narrower for RATKA compared with the mTKA group (Femur coronal: mean 1.31, 95% confidence interval (CI) 1.08-1.55, p<0.00001; Tibia coronal: mean 1.56, 95% CI 1.32-1.81, p<0.00001). Three studies reported using different alignment and balancing techniques between mTKA and RATKA, two studies used the same for both group and two studies did not state the methods used in their RATKA groups. RATKA resulted in better Knee Society Score compared to mTKA in the short-to-mid-term follow up (95%CI [- 1.23, - 0.51], p=0.004). There was no difference in arthrofibrosis, superficial and deep infection, wound dehiscence, or overall complication rates. RATKA demonstrated improved accuracy of component positioning and patient-reported outcomes. The learning curve of RATKA for operating time was between 7 and 11 cases. Future well-powered studies on RATKAs should report on the knee alignment and balancing techniques utilised to enable better comparisons on which techniques maximise patient outcomes.Level of evidence III.
41Component placement accuracy in two generations of handheld robotics-assisted knee arthroplasty.PubMed
Chelsea S Sicat, James C Chow, Bertrand Kaper, et al.
Arch Orthop Trauma Surg. 2021 Dec;141(12):2059-2067. doi: 10.1007/s00402-021-04040-6. Epub 2021 Jul 25.
INTRODUCTION: Total knee arthroplasty (TKA) is the gold standard for treatment of end-stage osteoarthritis. Previous studies have shown that successful outcomes following TKA depend on accurate implant alignment and soft tissue balancing. Robotic-assisted TKA have demonstrated improved accuracy in component placement and have been associated with better outcomes and patient satisfaction. This study aims to report on the execution accuracy of two generations of handheld robotic-assisted surgical systems. METHODS: This was a retrospective analysis of TKA procedures with two sequential generations of the same handheld robotic-assisted surgical system. Intra-operative data captured included pre-operative limb deformity, limb axes, range of motion, kinematic balance, and the resulting plan for component placement in three-dimensional space. Patients were stratified based on their preoperative coronal lower limb mechanical alignment (> 3° varus, < 3° varus, < 3° valgus, and ≥ 3° valgus). Measurements of component placement (overall lower limb alignment, medial and lateral flexion gaps, and tibial and femoral resection depths) were assessed using descriptive statistics. RESULTS: A total of 435 patients were included and stratified based on preoperative lower limb alignment: 229 with ≥ 3° varus, 78 with varus < 3° and 58 with valgus < 3°, and 70 with valgus > 3°. The mean difference between planned and achieved alignment in the lower limb valgus patients was < 1° across all groups. Mean differences between planned and achieved medial flexion gap was higher in the > 3° subgroup in the varus patient cohort ([< 3°]: 1.15 ± 1.92 vs. [> 3°]: 1.90 ± 2.57); this value was higher in the < 3° subgroup for valgus patients ([< 3°]: 1.34 ± 1.83 vs. [> 3°]: 0.956 ± 1.65). Average resection depth ranged from 9.46 to 10.4 mm in the posterior medial femur, 9.25 to 9.95 mm in the posterior lateral femur, 7.45 to 8.79 mm in the distal medial femur, 8.22 to 9.18 mm in the distal lateral femur, 6.70 to 7.07 mm in the medial tibial condyle and 6.40 to 7.19 mm in the lateral tibial condyle. Non-inferiority testing demonstrated the newer generation is non-inferior to the older generation. CONCLUSION: Robotic-assisted knee replacement using handheld image-free systems is able to maintain accuracy of component placement. Further investigation of patient reported outcomes as well as long-term implant longevity are needed.
42Mapping knowledge landscapes and emerging trends of robotic-assisted knee arthroplasty: A bibliometric analysis.PubMed
Dongping Wan, Rui Wang, Jie Wei, et al.
Medicine (Baltimore). 2023 Sep 22;102(38):e35076. doi: 10.1097/MD.0000000000035076.
The robotic-assisted knee arthroplasty has gained increasing attention in the research field. To date, no comprehensive bibliometric analysis has been carried out on this topic. The present study aimed to introduce the research status and hotspots and explore the field of robotic-assisted knee arthroplasty from a bibliometric perspective. The Web of Science Core Collection database was utilized to retrieve articles and reviews on robotic-assisted knee arthroplasty published between 1993 and 2023. CiteSpace, VOSviewer, Scimago Graphica, Pajek, and a bibliometric online analysis platform (http://bibliometric.com/) were employed to analyze the regions, institutions, journals, authors, and keywords, aiming to predict the latest trends in research related to robotic-assisted knee arthroplasty. This study encompasses 697 records. The annual publication count pertaining to robotic-assisted knee arthroplasty demonstrates consistent growth. The United States leads with the highest number of studies (298), trailed by the United Kingdom (110) and France (49). The Hospital for Special Surgery emerges as the most prolific institution, while Professor Mont, Michael A holds significant author influence. The Journal of Arthroplasty reigns supreme in this field, boasting the highest publication and citation figures. Funding sources predominantly include Stryker (34), Smith Nephew (19), and the National Natural Science Foundation of China (17). Noteworthy research themes within robotic-assisted knee arthroplasty encompass patient satisfaction, kinematic alignment, and clinical benefits. The landscape of robotic-assisted knee arthroplasty research is thriving. Anticipated trajectories of research will be geared toward refining the precision of robotic technology and enhancing clinical outcomes within the realm of robotic-assisted knee arthroplasty.
43Individualized alignment in total knee arthroplasty using image-based robotic assistance : Video article.PubMed
Tilman Calliess, Max Ettinger, Peter Savov, et al.
Orthopade. 2018 Oct;47(10):871-879. doi: 10.1007/s00132-018-3637-1.
INTRODUCTION: Over the past decades many innovations were introduced in total knee arthroplasty (TKA) focusing on implant longevity and higher procedural precision; however, there are still a high number of dissatisfied patients. It was reported that better anatomical alignment may result in improved patient outcome; however, current technologies have limitations to achieve this. The aim of this video article is to describe the technique of individualized alignment in TKA with the use of image-based robotic assistance. METHODS: The technology is based on an individual patient knee model computed from segmented computed tomography (CT) scans. A preoperative planning of prosthesis position is conducted following the principle of kinematic alignment. Intraoperatively the soft tissue envelope is recorded and the computer predicts the gap balance based on the virtual planning. The prosthesis position is then adapted to achieve balanced gaps and to avoid soft tissue release. This technique is shown in a cadaver operation and clinical examples of two patients are described. RESULTS: With the combination of anatomically oriented prosthesis positioning and minor adaptations with respect to the soft tissue, an individualized alignment is achieved with reduced need of soft tissue release. The robotic-assisted surgery guarantees a precise implementation of the planning. The initial experience showed a promising outcome in short-term follow-up.
44Latest Advances in Robot-Assisted Knee Arthroplasty.PubMed
Dinesh Nathwani, Ravikiran Shenoy
Surg Technol Int. 2021 Oct 26;39:331-337. doi: 10.52198/21.STI.39.OS1423.
In the longstanding pursuit of improving alignment and functional outcome in knee arthroplasty, technological evolution leading to robotic systems has now been introduced to the mainstream orthopaedic surgical world. This technology facilitates greater accuracy in implant placement, protects soft tissues, and achieves better balancing, while also allowing the potential to be more bone conserving. Robots currently in use in orthopaedic surgery can be classified into passive or haptic semi-active surgeon-guided systems. Using a virtual model of the knee joint, the robot system guides bone cuts and facilitates precise implant placement. In addition, small changes to bone resection can be made permitting deformity correction and balancing. This is achieved on-table by dynamic referencing, which enables live objective measurement of range of movements, stability, and gap balance throughout the range of motion. Preservation of ligaments and their unnecessary releases has been shown to reduce time to recovery and allow potentially better knee kinematics. Advances in robot technology in knee arthroplasty have led to the development of a variety of systems to execute the multiple steps in this procedure including using computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, plain radiographs (image based), or image-free systems. The combination of these images and on-table registering of bony landmarks allow the creation of a 3-dimensional (3D) virtual, but accurate, model of the knee during surgery. The various systems apply sculpting tools, burrs, or cutting saws to deliver the bone cuts or allow robots to guide placement of cutting blocks to ensure accurate pre-planned bone cuts. Intraoperative adjustments to bone resections can be made using a variety of tracker systems to measure joint movement and ligament balance to correct any malalignments while performing the surgery, so compound errors in the technique are avoided. Data from comparative studies suggest improved accuracy in implant placement in patients compared to conventional knee arthroplasty. Benefits of robot assistance have been demonstrated both in total knee arthroplasty and unicompartmental knee arthroplasty. Recent studies show a trend toward improved patient-reported outcomes and better patient satisfactions as well as earlier recoveries following robot-assisted knee arthroplasty. Early survivorship data has also shown a better survivorship with robot-assisted knee arthroplasty, although long-term survivorship data are awaited. An increase in familiarity, availability, and demand for this technology is driving innovations aimed at delivering a personalized approach to knee arthroplasty. This chapter will discuss the latest advances and look at the clinical research in relation to the robotic technological advancement comparing some of the different system approaches.
45Does Robotic-assisted TKA Result in Better Outcome Scores or Long-Term Survivorship Than Conventional TKA? A Randomized, Controlled Trial.PubMed
Young-Hoo Kim, Sung-Hwan Yoon, Jang-Won Park
Clin Orthop Relat Res. 2020 Feb;478(2):266-275. doi: 10.1097/CORR.0000000000000916.
BACKGROUND: Robotic-assisted TKA was introduced to enhance the precision of bone preparation and component alignment with the goal of improving the clinical results and survivorship of TKA. Although numerous reports suggest that bone preparation and knee component alignment may be improved using robotic assistance, no long-term randomized trials of robotic-assisted TKA have shown whether this results in improved clinical function or survivorship of the TKA. QUESTIONS/PURPOSES: In this randomized trial, we compared robotic-assisted TKA to manual-alignment techniques at long-term follow-up in terms of (1) functional results based on Knee Society, WOMAC, and UCLA Activity scores; (2) numerous radiographic parameters, including component and limb alignment; (3) Kaplan-Meier survivorship; and (4) complications specific to robotic-assistance, including pin-tract infection, peroneal nerve palsy, pin-site fracture, or patellar complications. METHODS: This study was a registered prospective, randomized, controlled trial. From January 2002 to February 2008, one surgeon performed 975 robotic-assisted TKAs in 850 patients and 990 conventional TKAs in 849 patients. Among these patients 1406 patients were eligible for participation in this study based on prespecified inclusion criteria. Of those, 100% (1406) patients agreed to participate and were randomized, with 700 patients (750 knees) receiving robotic-assisted TKA and 706 patients (766 knees) receiving conventional TKA. Of those, 96% (674 patients) in the robotic-assisted TKA group and 95% (674 patients) in the conventional TKA group were available for follow-up at a mean of 13 (± 5) years. In both groups, no patient older than 65 years was randomized because we anticipated long-term follow-up. We evaluated 674 patients (724 knees) in each group for clinical and radiographic outcomes, and we examined Kaplan-Meier survivorship for the endpoint of aseptic loosening or revision. Clinical evaluation was performed using the original Knee Society knee score, the WOMAC score, and the UCLA activity score preoperatively and at latest follow-up visit. We also assessed loosening (defined as change in the position of the components) using plain radiographs, osteolysis using CT scans at the latest follow-up visit, and component, and limb alignment on mechanical axis radiographs. To minimize the chance of type-2 error and increase the power of our study, we assumed the difference in the Knee Society score to be 25 points to match the MCID of the Knee Society score with a SD of 5; to be able to detect a difference of this size, we calculated that a total of 628 patients would be needed in each group in order to achieve 80% power at the α = 0.05 level. RESULTS: Clinical parameters at the latest follow-up including the Knee Society knee scores (93 ± 5 points in the robotic-assisted TKA group versus 92 ± 6 points in the conventional TKA group [95% confidence interval 90 to 98]; p = 0.321) and Knee Society knee function scores (83 ± 7 points in the robotic-assisted TKA group versus 85 ± 6 points in the conventional TKA group [95% CI 75 to 88]; p = 0.992), WOMAC scores (18 ± 14 points in the robotic-assisted TKA group versus 19 ± 15 points in the conventional TKA group [95% CI 16 to 22]; p = 0.981), range of knee motion (125 ± 6° in the robotic-assisted TKA group versus 128 ± 7° in the conventional TKA group [95% CI 121 to 135]; p = 0.321), and UCLA patient activity scores (7 points versus 7 points in each group [95% CI 5 to 10]; p = 1.000) were not different between the two groups at a mean of 13 years' follow-up. Radiographic parameters such as the femorotibial angle (mean 2° ± 2° valgus in the robotic-assisted TKA group versus 3° ± 3° valgus in the conventional TKA group [95% CI 1 to 5]; p = 0.897), femoral component position (coronal plane: mean 98° in the robotic-assisted TKA group versus 97° in the conventional TKA group [95% CI 96 to 99]; p = 0.953; sagittal plane: mean 3° in the robotic-assisted TKA group versus 2° in the conventional TKA group [95% CI 1 to 4]; p = 0.612) and tibial component position (coronal plane: mean 90° in the robotic-assisted TKA group versus 89° in the conventional TKA group [95% CI 87 to 92]; p = 0.721; sagittal plane: 87° in the robotic-assisted TKA group versus 86° in the conventional TKA group [95% CI 84 to 89]; p = 0.792), joint line (16 mm in the robotic-assisted TKA group versus 16 mm in the conventional TKA group [95% CI 14 to 18]; p = 0.512), and posterior femoral condylar offset (24 mm in the robotic-assisted TKA group versus 24 mm in the conventional TKA group [95% CI 21 to 27 ]; p = 0.817) also were not different between the two groups (p > 0.05). The aseptic loosening rate was 2% in each group, and this was not different between the two groups. With the endpoint of revision or aseptic loosening of the components, Kaplan-Meier survivorship of the TKA components was 98% in both groups (95% CI 94 to 100) at 15 years (p = 0.972). There were no between-group differences in terms of the frequency with which complications occurred. In all, 0.6% of knees (four) in each group had a superficial infection, and they were treated with intravenous antibiotics for 2 weeks [corrected]. No deep infection occurred in these knees. In the conventional TKA group, 0.6% of knees (four) had motion limitation (< 60°) [corrected]. CONCLUSIONS: At a minimum follow-up of 10 years, we found no differences between robotic-assisted TKA and conventional TKA in terms of functional outcome scores, aseptic loosening, overall survivorship, and complications. Considering the additional time and expense associated with robotic-assisted TKA, we cannot recommend its widespread use. LEVEL OF EVIDENCE: Level I, therapeutic study.
46Comparing Rates of Minimal Clinically Important Difference Between Manual and Robotic-Assisted Total Knee Arthroplasty.PubMed
Marcos R Gonzalez, Perry L Lim, Antonia F Chen, et al.
J Arthroplasty. 2025 Mar;40(3):637-643. doi: 10.1016/j.arth.2024.08.039. Epub 2024 Aug 30.
BACKGROUND: Differences in patient-reported outcome measures (PROMs) between manual total knee arthroplasty (mTKA) and robotic-assisted TKA (rTKA) have not been adequately assessed. We compared the minimal clinically important difference (MCID) for improvement (MCID-I) and worsening (MCID-W) between mTKA and rTKA patients. METHODS: Patients who underwent primary TKA (874 mTKA and 439 rTKA) with complete preoperative and 1-year postoperative PROMs were retrospectively identified using a multihospital joint arthroplasty registry. Patient-Reported Outcomes Measurement Information System Physical Function Short Form 10a (PROMIS PF-10a), PROMIS Global - Physical, or Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form were collected. The MCID-I, MCID-W, and "no significant change" rates were calculated using distribution-based methods. Propensity score matching was performed to control for confounding. RESULTS: Similar 90-day pulmonary embolism (P = 0.26), deep venous thrombosis (P = 0.67), and emergency department visit (P = 0.35) rates were found. The 90-day readmission rate for mTKA was 1.7 and 3.4% for rTKA (P = 0.08), and the overall revision rates were 2.2% for mTKA and 0.7% for rTKA (P = 0.07). Revision-free survival was 99% at one and 2 years for both groups (P = 0.65 and P = 0.43, respectively). There were no differences in the proportion of patients achieving MCID-I or MCID-W for PROMIS PF-10a, PROMIS Global - Physical, or Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form. The MCID-I for PROMIS PF-10a was achieved in 65.5 and 62.2% of patients who had mTKA and rTKA, respectively (P = 0.32). CONCLUSIONS: Our study demonstrated similar complication rates and MCID-I and MCID-W attainment rates between mTKA and rTKA patients. Future studies should assess MCID attainment rates in the long term and in larger cohorts comparing mTKA and rTKA.
47Robotic-arm assisted total knee arthroplasty is associated with improved early functional recovery and reduced time to hospital discharge compared with conventional jig-based total knee arthroplasty: a prospective cohort study.PubMed
B Kayani, S Konan, J Tahmassebi, et al.
Bone Joint J. 2018 Jul;100-B(7):930-937. doi: 10.1302/0301-620X.100B7.BJJ-2017-1449.R1.
AIMS: The objective of this study was to compare early postoperative functional outcomes and time to hospital discharge between conventional jig-based total knee arthroplasty (TKA) and robotic-arm assisted TKA. PATIENTS AND METHODS: This prospective cohort study included 40 consecutive patients undergoing conventional jig-based TKA followed by 40 consecutive patients receiving robotic-arm assisted TKA. All surgical procedures were performed by a single surgeon using the medial parapatellar approach with identical implant designs and standardized postoperative inpatient rehabilitation. Inpatient functional outcomes and time to hospital discharge were collected in all study patients. RESULTS: There were no systematic differences in baseline characteristics between the conventional jig-based TKA and robotic-arm assisted TKA treatment groups with respect to age (p = 0.32), gender (p = 0.50), body mass index (p = 0.17), American Society of Anesthesiologists score (p = 0.88), and preoperative haemoglobin level (p = 0.82). Robotic-arm assisted TKA was associated with reduced postoperative pain (p < 0.001), decreased analgesia requirements (p < 0.001), decreased reduction in postoperative haemoglobin levels (p < 0.001), shorter time to straight leg raise (p < 0.001), decreased number of physiotherapy sessions (p < 0.001) and improved maximum knee flexion at discharge (p < 0.001) compared with conventional jig-based TKA. Median time to hospital discharge in robotic-arm assisted TKA was 77 hours (interquartile range (IQR) 74 to 81) compared with 105 hours (IQR 98 to 126) in conventional jig-based TKA (p < 0.001). CONCLUSION: Robotic-arm assisted TKA was associated with decreased pain, improved early functional recovery and reduced time to hospital discharge compared with conventional jig-based TKA. Cite this article: Bone Joint J 2018;100-B:930-7.
48Combining load sensor and robotic technologies for ligament balance in total knee arthroplasty.PubMed
Julien Bardou-Jacquet, Jérome Murgier, François Laudet, et al.
Orthop Traumatol Surg Res. 2022 Sep;108(5):102889. doi: 10.1016/j.otsr.2021.102889. Epub 2021 Mar 10.
Good ligament balance in total knee arthroplasty (TKA) is thought to improve clinical results, but is highly surgeon-dependent when performed without technological assistance. We therefore describe a TKA technique using the Mako robotic arm (Stryker, Kalamazoo, Michigan, USA) as sole means of balancing ligament tension by bone recuts associated to control by the VERASENSE load sensor (Orthosensor, Inc, Dania Beach, Florida, USA). In this preliminary series of 29 patients, 27 (93%) showed a well-balanced knee in extension at end of procedure, and 23 (79%) showed a well-balanced knee in flexion and extension, without any periarticular soft-tissue release. The load sensor analyzes ligament balance after the initial bone cuts, and guides possible further femoral or tibial recuts. This technique enables quantifiable alignment and control of ligament tension. Collecting objective intraoperative data should improve knowledge in placing TKA prostheses.
49Computer-assisted navigation in knee surgery.PubMed
George Mimidis, Andreas F Mavrogenis, Olga D Savvidou, et al.
J Long Term Eff Med Implants. 2012;22(4):313-22. doi: 10.1615/jlongtermeffmedimplants.2013007080.
Although computer-assisted navigation has been used in clinical practice for more than 15 years, it has only recently started to gain acceptance in a variety of orthopedic procedures. Different types of computer-assisted navigation are available, which allow the surgeon to obtain real-time feedback and offer him the potential to decrease intraoperative errors. However, its increased cost and lacking evidence of long-term superiority have made many surgeons skeptical about its clinical usefulness. The scope of this article is to review the clinical applications of computer-assisted navigation in orthopedic surgery of the knee joint.
50Current Role of Computer Navigation in Total Knee Arthroplasty.PubMed
Christopher W Jones, Seth A Jerabek
J Arthroplasty. 2018 Jul;33(7):1989-1993. doi: 10.1016/j.arth.2018.01.027. Epub 2018 Jan 31.
BACKGROUND: Computer-assisted surgical (CAS) navigation has been developed with the aim of improving the accuracy and precision of total knee arthroplasty (TKA) component positioning and therefore overall limb alignment. The historical goal of knee arthroplasty has been to restore the mechanical alignment of the lower limb by aligning the femoral and tibial components perpendicular to the mechanical axis of the femur and tibia. Despite over 4 decades of TKA component development and nearly 2 decades of interest in CAS, the fundamental question remains; does the alignment goal and/or the method of achieving that goal affect the outcome of the TKA in terms of patient-reported outcome measures and/or overall survivorship? The quest for reliable and reproducible achievement of the intraoperative alignment goal has been the primary motivator for the introduction, development, and refinement of CAS navigation. Numerous proprietary systems now exist, and rapid technological advancements in computer processing power are stimulating further development of robotic surgical systems. Three categories of CAS can be defined: image-based large-console navigation; imageless large-console navigation, and more recently, accelerometer-based handheld navigation systems have been developed. CONCLUSION: A review of the current literature demonstrates that there are enough well-designed studies to conclude that both large-console CAS and handheld navigation systems improve the accuracy and precision of component alignment in TKA. However, missing from the evidence base, other than the subgroup analysis provided by the Australian Orthopaedic Association National Joint Replacement Registry, are any conclusive demonstrations of a clinical superiority in terms of improved patient-reported outcome measures and/or decreased cumulative revision rates in the long term. Few authors would argue that accuracy of alignment is a goal to ignore; therefore, in the absence of clinical evidence, many of the arguments against the use of large-console CAS navigation center on the prohibitive cost of the systems. The utilization of low-cost, handheld CAS navigation systems may therefore bridge this important gap, and over time, further clinical evidence may emerge.
52Patient-Specific Instrumentation in Total Knee Arthroplasty: What Is the Evidence?PubMed
Bartlomiej Szczech, James D McDermott, Kimona Issa, et al.
J Knee Surg. 2016 May;29(4):341-5. doi: 10.1055/s-0035-1558859. Epub 2015 Sep 17.
With a steady increase in the demand for primary and revision total knee arthroplasty (TKA), any potential reduction in the number of failures can be a topic of significant clinical importance. Patient-specific instrumentation (PSI) is introduced to potentially achieve more reproducible alignment with reduced outliers by creating more accurate and patient-specific femoral and tibial cuts based on neutral mechanical axis. However, there is no widely accepted consensus on the efficacy and indication of using PSI in TKA. The purpose of this review was to assess the current literature on patient-specific TKA and its effect on perioperative outcomes, including templating and preoperative planning, mechanical alignment, clinical outcomes, perioperative blood loss, and economic evaluations. Based on the current literature, more prospective studies are necessary to evaluate the routine use of PSI in TKA.
53Systematic review of patient-specific instrumentation in total knee arthroplasty: new but not improved.PubMed
Adam Sassoon, Denis Nam, Ryan Nunley, et al.
Clin Orthop Relat Res. 2015 Jan;473(1):151-8. doi: 10.1007/s11999-014-3804-6.
BACKGROUND: Patient-specific cutting blocks have been touted as a more efficient and reliable means of achieving neutral mechanical alignment during TKA with the proposed downstream effect of improved clinical outcomes. However, it is not clear to what degree published studies support these assumptions. QUESTIONS/PURPOSES: We asked: (1) Do patient-specific cutting blocks achieve neutral mechanical alignment more reliably during TKA when compared with conventional methods? (2) Does patient-specific instrumentation (PSI) provide financial benefit through improved surgical efficiency? (3) Does the use of patient-specific cutting blocks translate to improved clinical results after TKA when compared with conventional instrumentation? METHODS: We performed a systematic review in accordance with Cochrane guidelines of controlled studies (prospective and retrospective) in MEDLINE® and EMBASE® with respect to patient-specific cutting blocks and their effect on alignment, cost, operative time, clinical outcome scores, complications, and survivorship. Sixteen studies (Level I-III on the levels of evidence rubric) were identified and used in addressing the first question, 13 (Level I-III) for the second question, and two (Level III) for the third question. Qualitative assessment of the selected Level I studies was performed using the modified Jadad score; Level II and III studies were rated based on the Newcastle-Ottawa scoring system. RESULTS: The majority of studies did not show an improvement in overall limb alignment when PSI was compared with standard instrumentation. Mixed results were seen across studies with regard to the prevalence of alignment outliers when PSI was compared with conventional cutting blocks with some studies demonstrating no difference, some showing an improvement with PSI, and a single study showing worse results with PSI. The studies demonstrated mixed results regarding the influence of PSI on operative times. Decreased operative times were not uniformly observed, and when noted, they were found to be of minimal clinical or financial significance. PSI did reliably reduce the number of instrument trays required for processing perioperatively. The accuracy of the preoperative plan, generated by the PSI manufacturers, was found lacking, often leading to multiple intraoperative changes, thereby disrupting the flow of the operation and negatively impacting efficiency. Limited data exist with regard to the effect of PSI on postoperative function, improvement in pain, and patient satisfaction. Neither of the two studies we identified provided strong evidence to support an advantage favoring the use of PSI. No identified studies addressed survivorship of components placed with PSI compared with those placed with standard instrumentation. CONCLUSIONS: PSI for TKA has not reliably demonstrated improvement of postoperative limb or component alignment when compared with standard instrumentation. Although decisive evidence exists to support that PSI requires fewer surgical trays, PSI has not clearly been shown to improve overall surgical efficiency or the cost-effectiveness of TKA. Mid- and long-term data regarding PSI's effect on functional outcomes and component survivorship do not exist and short-term data are scarce. Limited available literature does not clearly support any improvement of postoperative pain, activity, function, or ROM when PSI is compared with traditional instrumentation.
54Efficacy of Patient-Specific Instruments in Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.PubMed
Emmanuel Thienpont, Pierre-Emmanuel Schwab, Peter Fennema
J Bone Joint Surg Am. 2017 Mar 15;99(6):521-530. doi: 10.2106/JBJS.16.00496.
BACKGROUND: Patient-specific instrumentation (PSI) was introduced with the aim of making the procedure of total knee arthroplasty more accurate and efficient. The purpose of this study was to compare PSI and standard instrumentation in total knee arthroplasty with regard to radiographic and clinical outcomes as well as operative time and blood loss. METHODS: A meta-analysis was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. PubMed and Embase were searched from 2011 through 2015. We included randomized controlled trials and cohort studies that reported the effect of PSI on the aforementioned outcomes. The primary end point was deviation from the mechanical axis by >3°. Random and fixed-effect models were used for analysis. RESULTS: A total of 44 studies, which included 2,866 knees that underwent surgery with PSI and 2,956 knees that underwent surgery with standard instrumentation, were evaluated. The risk of mechanical axis malalignment was significantly lower for PSI, with a pooled relative risk of 0.79 (p = 0.013). The risk of tibial sagittal-plane malalignment was higher for PSI than for standard instrumentation (relative risk = 1.32, p = 0.001), whereas the risk of femoral coronal-plane malalignment was significantly lower (relative risk = 0.74, p = 0.043). The risk of tibial coronal-plane malalignment was significantly higher for PSI only when employing fixed-effect meta-analysis (relative risk = 1.33, p = 0.042). Minor reductions in total operative time (-4.4 minutes, p = 0.002) and blood loss (-37.9 mL, p = 0.015) were noted for PSI. CONCLUSIONS: PSI improves the accuracy of femoral component alignment and global mechanical alignment, but at the cost of an increased risk of outliers for the tibial component alignment. The impact of the increased probability of tibial component malalignment on implant longevity remains to be determined. Meta-analyses indicated significant differences with regard to operative time and blood loss in favor of PSI. However, these differences were minimal and, by themselves, not a substantial justification for routine use of the technology. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.
55Patient-specific instrumentation does not improve radiographic alignment or clinical outcomes after total knee arthroplasty.PubMed
Henricus J T A M Huijbregts, Riaz J K Khan, Emma Sorensen, et al.
Acta Orthop. 2016 Aug;87(4):386-94. doi: 10.1080/17453674.2016.1193799. Epub 2016 Jun 1.
Background and purpose - Patient-specific instrumentation (PSI) for total knee arthroplasty (TKA) has been introduced to improve alignment and reduce outliers, increase efficiency, and reduce operation time. In order to improve our understanding of the outcomes of patient-specific instrumentation, we conducted a meta-analysis. Patients and methods - We identified randomized and quasi-randomized controlled trials (RCTs) comparing patient-specific and conventional instrumentation in TKA. Weighted mean differences and risk ratios were determined for radiographic accuracy, operation time, hospital stay, blood loss, number of surgical trays required, and patient-reported outcome measures. Results - 21 RCTs involving 1,587 TKAs were included. Patient-specific instrumentation resulted in slightly more accurate hip-knee-ankle axis (0.3°), coronal femoral alignment (0.3°, femoral flexion (0.9°), tibial slope (0.7°), and femoral component rotation (0.5°). The risk ratio of a coronal plane outlier (> 3° deviation of chosen target) for the tibial component was statistically significantly increased in the PSI group (RR =1.64). No significance was found for other radiographic measures. Operation time, blood loss, and transfusion rate were similar. Hospital stay was significantly shortened, by approximately 8 h, and the number of surgical trays used decreased by 4 in the PSI group. Knee Society scores and Oxford knee scores were similar. Interpretation - Patient-specific instrumentation does not result in clinically meaningful improvement in alignment, fewer outliers, or better early patient-reported outcome measures. Efficiency is improved by reducing the number of trays used, but PSI does not reduce operation time.
56Patient-specific instrumentation for total knee arthroplasty: a literature review.PubMed
L Camarda, A D'Arienzo, S Morello, et al.
Musculoskelet Surg. 2015 Apr;99(1):11-8. doi: 10.1007/s12306-014-0339-7. Epub 2014 Oct 11.
During the past decade, total knee arthroplasty (TKA) has been markedly increased. Recently, patient-specific custom cutting guides have been commercially introduced in order to achieve an accurate component alignment during TKA. In fact, these cutting blocks are specific to a patient's knee anatomy and should help the surgeons to perform bone cuts, reducing the complexity of conventional alignment and sizing tools. Nevertheless, there are critical arguments against patient-specific cutting guides for routine use, such as poor evidence and higher costs. Additionally, there are still no mild and long-term results available that describe the clinical outcomes following patient-specific instrumentation of TKR, cost-effectiveness and lower revision rates. Aim of the current manuscript was to describe the recent improvements of the surgical technique and instrumentation of TKA, reviewing the recent literature concerning the PSI technology.
57Comparison of clinical outcomes of VISIONAIRE patient-specific instrumentation with conventional instrumentation in total knee arthroplasty: a systematic literature review and meta-analysis.PubMed
Carsten O Tibesku, Steven B Haas, Christopher Saunders, et al.
Arch Orthop Trauma Surg. 2023 Jul;143(7):4379-4393. doi: 10.1007/s00402-022-04698-6. Epub 2022 Nov 30.
INTRODUCTION: Malalignment and resulting complications are major challenges in total knee arthroplasty (TKA) which patient-specific instrumentation (PSI) is proposed to alleviate. Previous PSI meta-analyses of TKA outcomes typically do not differentiate between PSI systems and assess relatively few outcomes, so the value of their findings is limited. VISIONAIRE cutting guides (Smith + Nephew Inc., Memphis, TN, USA) is a PSI system based on preoperative magnetic resonance and X-ray imaging. A systematic literature review (SLR) and meta-analysis, focussed specifically on VISIONAIRE, were conducted to assess TKA accuracy, intraoperative outcomes, and postoperative outcomes, compared with conventional instrumentation (CI). MATERIALS AND METHODS: The SLR was performed using PubMed, Embase, and Google Scholar databases to identify relevant studies published until March 2022. Depending on statistical heterogeneity, meta-analyses were performed for outcome measures with fixed effect (I < 50%) or random-effects models (I ≥ 50%). Dichotomous outcomes were reported as odds ratios and continuous outcomes were reported as mean differences. Descriptive analyses were performed for outcomes not amenable to meta-analysis. RESULTS: Outcomes for VISIONAIRE versus CI were reported in 25 studies. Compared with CI, VISIONAIRE reduced odds of mechanical outliers by 40% (p < 0.0001), with no statistically significant differences in odds of overall coronal, sagittal, or rotational plane component outliers. VISIONAIRE improved surgical efficiency (operating room, turnover, and tourniquet times reduced by 7.3% (p = 0.02), 42% (p = 0.022), and 15.9% (p = 0.01), respectively), lowering the odds of blood transfusion by 53% (p = 0.01) and shortening patients' hospital stays (11.1% reduction; p < 0.0001). There were no significant differences between groups in incidence of postoperative complications and (descriptively analyzed) return-to-function outcomes. CONCLUSION: Options for PSI in TKA differ substantially, and it is important to assess the outcomes of individual systems. The current findings suggest that VISIONAIRE guides can lead to improved alignment accuracy and surgical efficiency compared with CI, without compromising postoperative safety and return-to-function outcomes.
58Customized Knee Prosthesis in Treatment of Giant Cell Tumors of the Proximal Tibia: Application of 3-Dimensional Printing Technology in Surgical Design.PubMed
Wenbin Luo, Lanfeng Huang, He Liu, et al.
Med Sci Monit. 2017 Apr 7;23:1691-1700. doi: 10.12659/msm.901436.
BACKGROUND We explored the application of 3-dimensional (3D) printing technology in treating giant cell tumors (GCT) of the proximal tibia. A tibia block was designed and produced through 3D printing technology. We expected that this 3D-printed block would fill the bone defect after en-bloc resection. Importantly, the block, combined with a standard knee joint prosthesis, provided attachments for collateral ligaments of the knee, which can maintain knee stability. MATERIAL AND METHODS A computed tomography (CT) scan was taken of both knee joints in 4 patients with GCT of the proximal tibia. We developed a novel technique - the real-size 3D-printed proximal tibia model - to design preoperative treatment plans. Hence, with the application of 3D printing technology, a customized proximal tibia block could be designed for each patient individually, which fixed the bone defect, combined with standard knee prosthesis. RESULTS In all 4 cases, the 3D-printed block fitted the bone defect precisely. The motion range of the affected knee was 90 degrees on average, and the soft tissue balance and stability of the knee were good. After an average 7-month follow-up, the MSTS score was 19 on average. No sign of prosthesis fracture, loosening, or other relevant complications were detected. CONCLUSIONS This technique can be used to treat GCT of the proximal tibia when it is hard to achieve soft tissue balance after tumor resection. 3D printing technology simplified the design and manufacturing progress of custom-made orthopedic medical instruments. This new surgical technique could be much more widely applied because of 3D printing technology.
59Design, analysis and verification of a knee joint oncological prosthesis finite element model.PubMed
Lukáš Zach, Lenka Kunčická, Pavel Růžička, et al.
Comput Biol Med. 2014 Nov;54:53-60. doi: 10.1016/j.compbiomed.2014.08.021. Epub 2014 Aug 26.
BACKGROUND: The aim of this paper was to design a finite element model for a hinged PROSPON oncological knee endoprosthesis and to verify the model by comparison with ankle flexion angle using knee-bending experimental data obtained previously. METHOD: Visible Human Project CT scans were used to create a general lower extremity bones model and to compose a 3D CAD knee joint model to which muscles and ligaments were added. Into the assembly the designed finite element PROSPON prosthesis model was integrated and an analysis focused on the PEEK-OPTIMA hinge pin bushing stress state was carried out. To confirm the stress state analysis results, contact pressure was investigated. The analysis was performed in the knee-bending position within 15.4-69.4° hip joint flexion range. RESULTS: The results showed that the maximum stress achieved during the analysis (46.6 MPa) did not exceed the yield strength of the material (90 MPa); the condition of plastic stability was therefore met. The stress state analysis results were confirmed by the distribution of contact pressure during knee-bending. CONCLUSION: The applicability of our designed finite element model for the real implant behaviour prediction was proven on the basis of good correlation of the analytical and experimental ankle flexion angle data.
60Spherical center and rotating platform hinged knee prosthesis: Finite-element model establishment, verification and contact analysis.PubMed
Jing-Yu Zhang, Jian Wang, Dong-Mu Tian, et al.
Knee. 2020 Jun;27(3):731-739. doi: 10.1016/j.knee.2020.04.022. Epub 2020 May 19.
BACKGROUND: Biomechanical study is fundamental for the preclinical evaluation of knee prostheses. However, there are few reports on the contact characteristic investigation in the hinged knee prosthesis. The purpose of this study was to investigate the contact characteristics of a novel hinged knee prosthesis. METHODS: All of the component models were designed and assembled using Solidworks. A comparison of the contact area and ultra-high-molecular-weight polyethylene (UHMWPE) deformation using the experimental method (EM) and finite-element analysis (FEA) under 3000 N with the prosthesis at different flexions was performed. The peak contact pressure and von Mises stress on tibial insert and bushing were investigated under nine specific samples that were extracted from a gait cycle using FEA (according to ISO 14243-1: 2009). RESULTS: The largest contact area and UHMWPE deformation were 100.78 ± 8.71 mm and 0.085 ± 0.015 mm in the EM, and 96.68 mm and 0.096 mm in FEA. The peak contact pressure and von Mises stress on the tibial insert were 26.3071 MPa and 10.5115 MPa at 13% of the gait cycle and on bushing were consistently 0 MPa. The contact pressures were distributed at the posterior of the insert. CONCLUSION: The finite-element model was validated to be applicable for predicting the real prosthesis behavior based on the good correlation of the results using the EM and FEA. The model can help to identify contact characteristics and be can used in optimization studies of this novel prosthesis during the design phase.
61Finite element analysis in the optimization of posterior-stabilized total knee arthroplasty.PubMed
Louis Dagneaux, François Canovas, Franck Jourdan
Orthop Traumatol Surg Res. 2024 Feb;110(1S):103765. doi: 10.1016/j.otsr.2023.103765. Epub 2023 Nov 17.
Posterior-stabilized total knee arthroplasty (PS-TKA) is associated with high rates of satisfaction and functional recovery. This is notably attributed to implant optimization in terms of design, choice of materials, positioning and understanding of biomechanics. Finite elements analysis (FEA) is an assessment technique that contributed to this optimization by ensuring mechanical results based on numerical simulation. By close teamwork between surgeons, researchers and engineers, FEA enabled testing of certain clinical impressions. However, the methodological features of the technique led to wide variations in the presentation and interpretation of results, requiring a certain understanding of numerical and biomechanical fields by the orthopedic community. The present study provides an up-to-date review, aiming to address the following questions: what are the principles of FEA? What is the role of FEA in studying PS design in TKA? What are the key elements in the literature for understanding the role of FEA in PS-TKA? What is the contribution of FEA for understanding of tibiofemoral and patellofemoral biomechanical behavior? What are the limitations and perspectives of digital simulation and FEA in routine practice, with a particular emphasis on the "digital twin" concept? LEVEL OF EVIDENCE: V, expert opinion.
62Finite element analysis: a comparison of an all-polyethylene tibial implant and its metal-backed equivalent.PubMed
S M Thompson, D Yohuno, W N Bradley, et al.
Knee Surg Sports Traumatol Arthrosc. 2016 Aug;24(8):2560-6. doi: 10.1007/s00167-015-3923-y. Epub 2015 Dec 22.
PURPOSE: The hypothesis of this study is that all-polyethylene (APE) tibial implants offer a biomechanical profile similar to metal-backed tray (MBT). There are significant financial implications, in selected patient groups, if APE can be deemed to perform as well as MBT. METHODS: Using a finite element analysis of CAD models provided by DePuy (Leeds), stress distributions were investigated for both an APE and MBT tibial implant. The performance was assessed for cancellous bone at 700 MPa (normal) and at 350 MPa (less stiff). Plots were recorded along the length of the tibia, showing the loads carried by the bone (cortical and cancellous), the implant interface, cement interface and the stem. von Mises stress distributions and percentage volumes were used to assess bone resorption and hence potential for failure (fracture). RESULTS: Higher stress shielding (resorption) occurred around the keel and stem of the MBT revealing greater potential for bone loss in these areas. APE had no areas of bone resorption (being more flexible resulting in less stress shielding). The stiffer MBT carries a higher proportion of the load down the stem. MBT stress in cancellous bone is lower than APE, as load is distributed to the cortical rim. APE has a marginally favourable strain state in cancellous bone and spreads loads more at the cement interface than MBT. CONCLUSION: Modern-day APE bearings may be superior to previously designed implants due to improvements in manufacturing. In the correct patient group, this could offer substantial cost savings.
63Effect of carbon-fiber-reinforced polyetheretherketone on stress distribution in a redesigned tumor-type knee prosthesis: a finite element analysis.PubMed
Han Wu, Yu Guo, Wei Guo
Front Bioeng Biotechnol. 2023 Sep 26;11:1243936. doi: 10.3389/fbioe.2023.1243936. eCollection 2023.
Surgery for bone tumors around the knee often involves extensive resection, making the subsequent prosthetic reconstruction challenging. While carbon fiber-reinforced polyetheretherketone (CF-PEEK) has been widely used in orthopedic implants, its application in tumor-type prosthesis is limited. This study aims to evaluate the feasibility of using 30wt% and 60wt% carbon fiber-reinforced polyetheretherketone (CF30-PEEK and CF60-PEEK) as materials for a redesigned tumor-type knee prosthesis through numerical analysis. A knee joint model based on CT data was created, and the resection and prosthetic reconstruction were simulated. Three finite element models of the prostheses, representing the initial and updated designs with CoCrMo and CFR-PEEK components, were constructed. Loading conditions during standing and squatting were simulated with forces of 700 N and 2800 N, respectively. Finite element analysis was used to analyze the von Mises stress and stability of all components for each prosthesis type. After improvements in both material and design, the new Type 3 prosthesis showed significantly lower overall stress with stress being evenly distributed. Compared with the initial design, the maximum von Mises stress in Type 3 was reduced by 53.9% during standing and 74.2% during squatting. In the standing position, the maximum stress in the CF30-PEEK femoral component decreased by 57.3% compared with the initial design which was composed of CoCrMo, while the stress in the CF60-PEEK cardan shaft remained consistent. In the squatting position, the maximum stress in the femoral component decreased by 81.9%, and the stress in the cardan shaft decreased by 46.5%. The incorporation of CF30-PEEK effectively transmits forces and reduces stress concentration on the femoral component, while CF60-PEEK in the redesigned cardan shaft significantly reduces stress while maintaining stiffness. The redesigned prosthesis effectively conducts loading force and demonstrates favorable biomechanical characteristics, indicating the promising potential of utilizing CF30-PEEK and CF60-PEEK materials for tumor-type knee prostheses. The findings of this study could provide novel insights for the design and development of tumor-type knee prostheses.
64Computational biomechanical study on hybrid implant materials for the femoral component of total knee replacements.PubMed
Jan-Oliver Sass, Maeruan Kebbach, Cornelia Lork, et al.
J Mech Behav Biomed Mater. 2024 Oct;158:106681. doi: 10.1016/j.jmbbm.2024.106681. Epub 2024 Aug 10.
Multifunctional materials have been described to meet the diverse requirements of implant materials for femoral components of uncemented total knee replacements. These materials aim to combine the high wear and corrosion resistance of oxide ceramics at the joint surfaces with the osteogenic potential of titanium alloys at the bone-implant interface. Our objective was to evaluate the biomechanical performance of hybrid material-based femoral components regarding mechanical stress within the implant during cementless implantation and stress shielding (evaluated by strain energy density) of the periprosthetic bone during two-legged squat motion using finite element modeling. The hybrid materials consisted of alumina-toughened zirconia (ATZ) ceramic joined with additively manufactured Ti-6Al-4V or Ti-35Nb-6Ta alloys. The titanium component was modeled with or without an open porous surface structure. Monolithic femoral components of ATZ ceramic or Co-28Cr-6Mo alloy were used as reference. The elasticity of the open porous surface structure was determined within experimental compression tests and was significantly higher for Ti-35Nb-6Ta compared to Ti-6Al-4V (5.2 ± 0.2 GPa vs. 8.8 ± 0.8 GPa, p < 0.001). During implantation, the maximum stress within the ATZ femoral component decreased from 1568.9 MPa (monolithic ATZ) to 367.6 MPa (Ti-6Al-4V/ATZ), 560.9 MPa (Ti-6Al-4V/ATZ with an open porous surface), 474.9 MPa (Ti-35Nb-6Ta/ATZ), and 648.4 MPa (Ti-35Nb-6Ta/ATZ with an open porous surface). The strain energy density increased at higher flexion angles for all models during the squat movement. At ∼90° knee flexion, the strain energy density in the anterior region of the distal femur increased by 25.7 % (Ti-6Al-4V/ATZ), 70.3 % (Ti-6Al-4V/ATZ with an open porous surface), 43.7 % (Ti-35Nb-6Ta/ATZ), and 82.5% (Ti-35Nb-6Ta/ATZ with an open porous surface) compared to monolithic ATZ. Thus, the hybrid material-based femoral component decreases the intraoperative fracture risk of the ATZ part and considerably reduces the risk of stress shielding of the periprosthetic bone.
65Mechanical alignment tolerance of a cruciate-retaining knee prosthesis under gait loading-A finite element analysis.PubMed
Yichao Luan, Huizhi Wang, Chaohua Fang, et al.
Front Bioeng Biotechnol. 2023 Mar 30;11:1148914. doi: 10.3389/fbioe.2023.1148914. eCollection 2023.
Component alignment is one of the most crucial factors affecting total knee arthroplasty's clinical outcome and survival. This study aimed to investigate how coronal, sagittal, and transverse malalignment affects the mechanical behavior of the tibial insert and to determine a suitable alignment tolerance on the coronal, sagittal, and transverse planes. A finite element model of a cruciate-retaining knee prosthesis was assembled with different joint alignments (-10°, -7°, -5°, -3°, 0°, 3°, 5°, 7°, 10°) to assess the effect of malalignment under gait loading. The results showed that varus or valgus, extension, internal rotation, and excessive external rotation malalignments increased the maximum Von Mises stress and contact pressure on the tibial insert. The mechanical alignment tolerance of the studied prosthesis on the coronal, sagittal, and transverse planes was 3° varus to 3° valgus, 0°-10° flexion, and 0°-5° external rotation, respectively. This study suggests that each prosthesis should include a tolerance range for the joint alignment angle on the three planes, which may be used during surgical planning.
66Incidence of periprosthetic joint infection after primary total knee arthroplasty shows significant variation : a synthesis of meta-analysis and bibliometric analysis.PubMed
Tao Ma, Jun Jiao, Da-Wei Guo, et al.
J Orthop Surg Res. 2024 Oct 12;19(1):649. doi: 10.1186/s13018-024-05099-8.
Total Knee Arthroplasty (TKA) is a surgery that is commonly performed on older adults to improve their quality of life. However, the increasing use of knee joint prostheses has led to a rise in the incidence of Prosthetic Joint Infections (PJI) in patients after TKA. Different clinical studies have looked at the occurrence of PJI after TKA in different regions, but they have drawn varying conclusions. To better understand this topic, we conducted a meta-analysis and bibliometric study using data from multiple databases. Our research found that the estimated prevalence of PJI after TKA is approximately 1.08% across different regions, but there is still considerable variation. Additionally, our regression analysis of sub-groups shows significant differences in follow-up periods. Furthermore, our comprehensive bibliometric analysis identifies current research trends, "hotspots" related to TKA-related PJI, influential nations, organizations, and noteworthy publications. Our analysis provides valuable insights to guide future research in this area.
67Preventive strategies to reduce the rate of periprosthetic infections in total joint arthroplasty; a comprehensive review.PubMed
Omer Faruk Egerci, Aliekber Yapar, Fırat Dogruoz, et al.
Arch Orthop Trauma Surg. 2024 Dec;144(12):5131-5146. doi: 10.1007/s00402-024-05301-w. Epub 2024 Apr 18.
The increasing frequency of total hip (THA) and knee arthroplasties (TKA) is marred by the rise in periprosthetic joint infections (PJIs) and surgical site infections (SSIs), with PJIs incurring costs over $1.62 billion as of 2020 and individual case management averaging $90,000. SSIs additionally burden the U.S. healthcare economy with billions in expenses annually. PJI prevalence in primary THA and TKA ranges from 0.5% to 2.4%, spiking to 20% in revisions and representing 25% of TKA revision causes. Projections estimate up to 270,000 annual PJI cases by 2030. Often caused by gram-positive bacteria, particularly methicillin-resistant staphylococci, these infections demand preventive measures. This review dissects PJI prevention across preoperative, intraoperative, and perioperative phases, aligning with evidence-based CDC and WHO guidelines. Preoperative measures include managing diabetes, obesity, tobacco use, Staphylococcus aureus screening and nasal decolonization, nutritional optimization, and management of inflammatory arthropathies. Intraoperatively, antibiotic prophylaxis, skin preparation, operative room environmental controls, surgical technique precision, and irrigation options are scrutinized. Perioperative concerns focus on anticoagulation, blood management, and infection risk mitigation. Integrating these strategies promotes a patient-centric care model, aiming to reduce PJI incidence, improve patient outcomes, and increase care cost-effectiveness in joint arthroplasty.
68Eradication rate after debridement, antibiotics, and implant retention (DAIR), 1.5-stage revision or 2-stage revision in periprosthetic ankle joint infection: A systematic review.PubMed
Antonio Izzo, Claudia Carbone, Vincenzo De Matteo, et al.
Foot Ankle Surg. 2025 May 14. doi: 10.1016/j.fas.2025.05.006.
OBJECTIVE: The management of periprosthetic joint infection (PJI) after total ankle replacement (TAR) may be challenging. Our aim was to define the eradication rate and limits of some of the surgical procedures commonly performed to treat acute and chronic PJI after TAR. METHODS: For this PRISMA-compliant systematic review multiple databases were searched including clinical studies in which acute or chronic PJI after TAR was diagnosed and treated. Data were harvested regarding the cohort, the study design, the diagnostic criteria adopted and the surgical treatment for PJI. The methodological index for nonrandomized studies (MINORS) was used to assess the methodological quality of studies. Three groups were built based on the surgical procedure performed in the studies: Group 1 for debridement, antibiotics, and implant retention (DAIR), Group 2 for 1.5-stage revision (1.5-stage) and Group 3 for 2-stage revision procedures (2-stage). RESULTS: Thirteen cohorts from seven studies (138 infected TARs; 40 % females, mean age 61.3 years) published between 2012 and 2023 were included. The definition of eradication of the infection was heterogenous among studies (reported as 'no more surgery' in 3 studies, normal clinical and serological markers in 2 studies and negative intraoperative cultures in 2 studies). The pooled eradication rate in DAIR, 1.5-stage and 2-stage revision groups was 89 % (95 %CI, 79-100), 95 % (95 %CI, 70-100) and 92 % (95 %CI, 80-99), respectively. The proportion of below-knee amputation was 7.2 % (10/138) at a mean 39.3-month follow-up. MINORS score (7.6/16 and 14.6/24 for noncomparative and comparative studies, respectively) revealed a poor quality of studies. CONCLUSIONS: In this review, the estimated effectiveness of DAIR, 1.5 and 2-stage exchange procedures to eradicate PJI after TAR was 89 %, 95 % and 92 %, respectively. Decision-making in this setting is based on small-sample retrospective studies of poor quality. Below-knee amputation rate after a diagnosis of PJI was 7.2 %. LEVEL OF EVIDENCE: Level IV, systematic review of Level IV studies.
69Local tissue concentrations of cefazolin during total joint arthroplasty: a systematic review.PubMed
Matthew Mannarino, Julien Montreuil, Michael Tanzer, et al.
Can J Surg. 2023 Aug 8;66(4):E415-E421. doi: 10.1503/cjs.019621. Print 2023 Jul-Aug.
BACKGROUND: Periprosthetic joint infections (PJI) following joint arthroplasty are now the leading cause of reoperation and are associated with serious morbidity to the patient, often requiring several staged operations and a prolonged course of parenteral antibiotics. Prophylactic administration of intravenous antibiotics before skin incision is arguably the most important measure to prevent PJI; however, the dose effectiveness of cefazolin in target tissue is not well known. We aimed to identify parameters affecting local tissue concentration (LTC) of cefazolin. METHODS: We performed a literature search using the following keywords: "orthopaedics," "orthopedic," "arthroplasty" and "cefazolin." We included studies that measured LTC of cefazolin from samples obtained during either a total knee or total hip arthroplasty. RESULTS: Of the 332 records screened, we included 10 studies that described LTC of cefazolin. The included studies evaluated dosing ( = 7), procedure type ( = 3), body mass index ( = 1) and tourniquet utilization ( = 1). CONCLUSION: Few studies have measured LTC levels of antibiotics (or levels of cefazolin) to validate current recommendations for antibiotic prophylaxis in orthopedic surgery. With infection as the leading reason for early reoperation or revision surgery, the parameters affecting LTC during orthopedic procedures need to be further assessed.
70Tourniquet Use and Local Tissue Concentrations of Cefazolin During Total Knee Arthroplasty: A Randomized Clinical Trial.PubMed
Julien Montreuil, Michael Tanzer, Yu Ling Zhang, et al.
JAMA Netw Open. 2024 Aug 1;7(8):e2429702. doi: 10.1001/jamanetworkopen.2024.29702.
IMPORTANCE: Prophylactic administration of antibiotics before skin incision is an important component in the prevention of periprosthetic joint infection in arthroplasty surgery. For antibiotics to be effective, the local tissue concentration (LTC) must exceed the minimum inhibitory concentration of typical infecting organisms; however, the LTC of cefazolin during arthroplasty is poorly understood. OBJECTIVE: To compare the systemic concentration of cefazolin in serum with the LTC in fat, synovium, and bone during primary total knee arthroplasty (TKA) while assessing the effect of tourniquet inflation. DESIGN, SETTING, AND PARTICIPANTS: This prospective randomized clinical trial was conducted from March 1, 2022, to June 30, 2023, in patients undergoing TKA at a single academic center. INTERVENTION: Total knee arthroplasty with or without a limb tourniquet. MAIN OUTCOMES AND MEASURES: Systemic blood and local tissues from the surgical site (fat, synovium, and bone) were harvested at regular intervals during the surgery. The primary outcome was the LTC of cefazolin, quantified using the liquid chromatography-tandem mass spectrometry technique. RESULTS: A total of 59 patients were included in the study, with 29 in the tourniquet group (mean [SD] age, 69.3 [9.6] years; 23 [79.3%] female) and 30 in the no tourniquet group (mean [SD] age, 69.9 [9.7] years; 21 [70.0%] female). In patients undergoing TKA without a tourniquet, the mean concentration of cefazolin in serum was 71.9 μg/mL (95% CI, 66.4-77.5 μg/mL), whereas the mean LTCs were 13.9 μg/g (95% CI, 12.1-15.7 μg/g) in fat, 27.7 μg/g (95% CI, 24.3-31.0 μg/g) in synovium, and 17.7 μg/g (95% CI, 14.8-20.5 μg/g) in bone. For patients undergoing TKA with a tourniquet, the mean concentration of cefazolin in serum was 72.0 μg/mL (95% CI, 66.3-77.7 μg/mL), and the mean LTCs were 9.9 μg/g (95% CI, 8.7-11.1 μg/g) in fat, 21.8 μg/g (95% CI, 18.7-25.0 μg/g) in synovium, and 13.0 μg/g (95% CI, 10.8-15.2 μg/g) in bone. The use of a tourniquet resulted in significantly lower mean LTCs by 60 minutes after cefazolin infusion (10.8 μg/g [95% CI, 9.1-12.4 μg/g] vs 16.9 μg/g [95% CI, 14.1-19.6 μg/g], P = .001 in fat; 18.9 μg/g [95% CI, 14.1-23.6 μg/g] vs 25.8 μg/g [95% CI, 21.4-30.3 μg/g], P = .03 in synovium; and 11.8 μg/g [95% CI, 9.3-14.2 μg/g] vs 19.4 μg/g [95% CI, 14.5-24.4 μg/g], P = .007 in bone). CONCLUSIONS AND RELEVANCE: In this randomized clinical trial, the concentration of cefazolin was lower in local tissues (fat, synovium, and bone) than in systemic blood, and the use of a limb tourniquet further significantly reduced these concentrations. Although the current prophylactic dosing regimen for cefazolin provides sufficient serum concentrations, the levels in the periarticular tissue during TKA may be insufficient to prevent periprosthetic joint infection. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05604157.
71Antibiotic prophylaxis and tourniquet inflation in total knee arthroplasty.PubMed
R J Friedman, L V Friedrich, R L White, et al.
Clin Orthop Relat Res. 1990 Nov(260):17-23.
Twenty-four patients receiving total knee arthroplasty (TKA) were randomized into one of three groups based on tourniquet inflation one, two, or five minutes after administration 1 g cefazolin. Simultaneous serum, soft-tissue, and bone samples were obtained at regular intervals during surgery. All soft-tissue and bone samples were corrected for cefazolin content. The percentage of cefazolin penetration into soft tissue and bone was calculated using the area under the concentration time curve. Adequate cefazolin concentrations for soft tissue and bone were defined as greater than or equal to 4 x minimum inhibitory concentration90 (MIC90 = 1 microgram/ml) of cefazolin to Staphylococcus aureus and coagulase-negative staphylococci. Patients were similar in age, actual body weight, creatinine clearance, and length of tourniquet inflation. The median percentage of cefazolin penetration into soft tissue and bone for the five-, two-, and one-minute groups was 14.5% and 4.6%, 6.7% and 3.0%, and 5.9% and 4.6%, respectively; the percentage of penetration into soft tissue between the five- and one-minute groups was statistically significant. A higher percentage of patients achieved the desired cefazolin concentration (greater than or equal to 4 micrograms/g) if a five-minute interval was selected. The five-minute group achieved the highest mean ratios of concentration to MIC compared with the two- and one-minute groups, although the differences were not statistically significant. The standard 1 g of cefazolin with a five-minute interval between administration and tourniquet inflation resulted in adequate mean soft-tissue and bone concentrations for prophylaxis during TKA with a tourniquet time less than two hours. Additional doses are not warranted after tourniquet release.
72Intraosseous Versus Intravenous Vancomycin in Tourniquetless Primary Total Knee Arthroplasty: A Randomized Trial.PubMed
Austin E Wininger, Pradyumna Gurusamy, Thomas C Sullivan, et al.
J Arthroplasty. 2024 Sep;39(9S2):S224-S228. doi: 10.1016/j.arth.2024.02.083. Epub 2024 Mar 8.
BACKGROUND: Intraosseous (IO) administration of vancomycin at the time of total knee arthroplasty (TKA) has been shown to be safer and more effective than intravenous (IV) administration at preventing early periprosthetic joint infection. Previous studies have relied on tourniquet inflation to enhance local tissue concentrations and mitigate systemic release. METHODS: A single-blinded, randomized clinical trial was performed on 20 patients (10 IV, 10 IO) undergoing primary TKA. The control (IV) group received weight-dosed vancomycin approximately 1 hour prior to the incision and weight-dosed cefazolin immediately prior to the incision. The interventional (IO) group received weight-dosed cefazolin immediately prior to the incision and 500 mg of vancomycin delivered via the IO technique at the time of the incision. Systemic samples for vancomycin levels were taken prior to the incision and at closure. During the procedure, tissue samples were taken from the distal femur, proximal tibia, and suprapatellar synovium. There were no differences in patient demographics or changes in serum creatinine from preoperative to postoperatively between groups. RESULTS: Significant differences in systemic vancomycin levels (ug/mL) were found at the start of the case (IV = 27.9 ± 4.9 versus IO = 0 ± 0, P = .0004) and at the end of the case (IV = 19.6 ± 2.6 versus IO = 7.8 ± 1.0, P = .001). No significant differences were seen in the average vancomycin concentration in the distal femur (IV = 61.0 ± 16.0 versus IO = 66.2 ± 12.3, P = .80), proximal tibia (IV = 52.8 ± 13.5 versus IO = 57.1 ± 17.0, P = .84), or suprapatellar synovial tissue (IV = 10.7 ± 5.3 versus IO = 9.0 ± 3.3, P = .80). There were no complications associated with vancomycin administration in either group. CONCLUSIONS: This study demonstrates the utility of IO vancomycin in tourniquetless TKA with similar local tissue and significantly lower systemic concentrations than IV administration. LEVEL OF EVIDENCE: Level 1 therapeutic randomized trial.
73Prolonged efficacy of cefazolin in intraosseous regional prophylaxis for total knee arthroplasty: a rabbit model study.PubMed
Jing-Yu Zhang, Ling-Chen Ye, Yu-Bo Liu, et al.
BMC Musculoskelet Disord. 2024 Feb 1;25(1):106. doi: 10.1186/s12891-024-07238-y.
BACKGROUND: A novel approach known as intraosseous regional administration (IORA) has emerged as a technique for delivering prophylactic antibiotics, and it results in higher tissue concentrations around the knee. It is hypothesized that IORA of cefazolin for antibiotic prophylaxis during total knee arthroplasty will result in sustained effective levels for a longer duration. The aim of the current study was to investigate temporal changes in peri-knee cefazolin blood concentrations after IORA of cefazolin. METHODS: Twelve rabbits were randomly divided into two groups, with six rabbits in each group. In control group a single intravenous bolus injection of cefazolin (10 mL, 100 mg) was administered into the marginal ear vein. In experimental groupexperimental group the same dose of cefazolin was injected into the left tibial marrow cavity after tourniquet inflation at the base of the left thigh. Blood samples were collected periodically at different timepoints, and cefazolin concentrations were determined. RESULTS: The intraosseous treatment resulted in significant differences in plasma cefazolin concentrations at all timepoints. Experimental group exhibited higher plasma cefazolin concentrations than control group. CONCLUSIONS: Cefazolin in intraosseous regional prophylaxis exhibits effectiveness in intraoperative antibiotic prophylaxis by maintaining concentrations above the minimum inhibitory concentration for extended durations, rather than relying solely on high concentrations.
74Periprosthetic Joint Infection After Total Knee Arthroplasty With or Without Antibiotic Bone Cement.PubMed
Tesfaye H Leta, Stein Atle Lie, Anne Marie Fenstad, et al.
JAMA Netw Open. 2024 May 1;7(5):e2412898. doi: 10.1001/jamanetworkopen.2024.12898.
IMPORTANCE: Despite increased use of antibiotic-loaded bone cement (ALBC) in joint arthroplasty over recent decades, current evidence for prophylactic use of ALBC to reduce risk of periprosthetic joint infection (PJI) is insufficient. OBJECTIVE: To compare the rate of revision attributed to PJI following primary total knee arthroplasty (TKA) using ALBC vs plain bone cement. DESIGN, SETTING, AND PARTICIPANTS: This international cohort study used data from 14 national or regional joint arthroplasty registries in Australia, Denmark, Finland, Germany, Italy, New Zealand, Norway, Romania, Sweden, Switzerland, the Netherlands, the UK, and the US. The study included primary TKAs for osteoarthritis registered from January 1, 2010, to December 31, 2020, and followed-up until December 31, 2021. Data analysis was performed from April to September 2023. EXPOSURE: Primary TKA with ALBC vs plain bone cement. MAIN OUTCOMES AND MEASURES: The primary outcome was risk of 1-year revision for PJI. Using a distributed data network analysis method, data were harmonized, and a cumulative revision rate was calculated (1 - Kaplan-Meier), and Cox regression analyses were performed within the 10 registries using both cement types. A meta-analysis was then performed to combine all aggregated data and evaluate the risk of 1-year revision for PJI and all causes. RESULTS: Among 2 168 924 TKAs included, 93% were performed with ALBC. Most TKAs were performed in female patients (59.5%) and patients aged 65 to 74 years (39.9%), fully cemented (92.2%), and in the 2015 to 2020 period (62.5%). All participating registries reported a cumulative 1-year revision rate for PJI of less than 1% following primary TKA with ALBC (range, 0.21%-0.80%) and with plain bone cement (range, 0.23%-0.70%). The meta-analyses based on adjusted Cox regression for 1 917 190 TKAs showed no statistically significant difference at 1 year in risk of revision for PJI (hazard rate ratio, 1.16; 95% CI, 0.89-1.52) or for all causes (hazard rate ratio, 1.12; 95% CI, 0.89-1.40) among TKAs performed with ALBC vs plain bone cement. CONCLUSIONS AND RELEVANCE: In this study, the risk of revision for PJI was similar between ALBC and plain bone cement following primary TKA. Any additional costs of ALBC and its relative value in reducing revision risk should be considered in the context of the overall health care delivery system.
75Acute periprosthetic knee infection: is there still a role for DAIR?PubMed
Paolo Di Benedetto, Enrico Daniele Di Benedetto, Daniele Salviato, et al.
Acta Biomed. 2017 Jun 7;88(2S):84-91. doi: 10.23750/abm.v88i2-S.6518.
BACKGROUND AND AIM OF THE WORK: Periprosthetic knee infection is a rare complication associated with prosthetic failure; incidence change from 0,4-2% of primary total knee replacement and 5.6% in revisions. Indications for debridment, antibiotics and implant retention (DAIR) are early acute infections or acute delayed infection. Aim of the work is to check if this technique is still a successful in early infections. METHODS: We have analyzed recent literature data on DAIR and all DAIR procedures in our clinic in the last 10 years, the mean time between onset of symptoms and surgery, the mean antibiotic therapy duration and results we have obtained. We evaluate the diagnostic process and different treatments in early knee periprosthetic infections, especially the DAIR approach. RESULTS: If correct indications are followed, DAIR has a success rate in 31-100% of the cases; if it is applied in late chronic infection the success rate is 28-62%. In our experience DAIR has an 80% success rate: in 20 patients treated with DAIR we had 4 failures. CONCLUSIONS: DAIR can be considered a successful treatment, but it depends from individual patient factors, from the microorganisms involved, from the duration of antibiotic therapy and from correct choice in timing and in execution of DAIR by the orthopedic surgeon.
76Debridement, antibiotics and implant retention (DAIR) for the management of knee prosthetic joint infection.PubMed
Kenneth Vaz, Matthew Scarborough, Nicholas Bottomley, et al.
Knee. 2020 Dec;27(6):2013-2015. doi: 10.1016/j.knee.2020.08.011. Epub 2020 Sep 17.
BACKGROUND: While two-stage revision arthroplasty is viewed as the gold standard for the treatment of knee periprosthetic joint infection (PJI) in terms of infection eradication, it is associated with significant cost along with patient morbidity and mortality. Debridement, antibiotics, and implant retention (DAIR) is an attractive option as it has demonstrated better patient outcomes, comparable implant longevity to primary arthroplasty, and significantly reduced cost when successful. Given the heterogeneity of what is defined as a DAIR the literature is highly variable in terms of its efficacy from the perspective of infection eradication. METHODS: In the setting of a previously well-functioning, well-fixed arthroplasty with an acceptable soft tissue envelope and a treatable organism we report our methods for proceeding with a DAIR procedure, both unicompartmental and total knee. RESULTS: With the above methods we have demonstrated improved patient outcomes when compared to one- or two-stage arthroplasty with lower patient morbidity. Implant longevity in the setting of a successful DAIR is equivalent to those of a primary arthroplasty. CONCLUSIONS: With appropriate indications and good surgical technique as described we believe DAIR is an excellent option in the treatment of periprosthetic joint infection. We hope that with a well-defined protocol as outlined we can gain a better understanding of the efficacy of DAIR procedure with more homogeneity to the procedure to better define when they are most successful while improving patient outcomes and reducing cost.
77Debridement, antibiotics, and implant retention for periprosthetic knee infections: a pooling analysis of 1266 cases.PubMed
Guo-Xin Qu, Cai-Hua Zhang, Shi-Gui Yan, et al.
J Orthop Surg Res. 2019 Nov 12;14(1):358. doi: 10.1186/s13018-019-1378-4.
BACKGROUND: The debridement, antibiotics, and implant retention (DAIR) procedure is an established therapeutic option for periprosthetic knee infections (PKI). However, the efficacy and the indication for this procedure are still controversial. METHODS: All the relevant literatures were systematically reviewed and analyzed. The present study aimed to assess the success rate of DAIR in the management of PKI, identify the factors associated with prognosis of DAIR, and establish a simple algorithm for predicting a high success rate of DAIR. RESULTS: Totally, 33 studies with 1266 cases were included. The overall success rate following DAIR in the management of PKI was 57.11%. In the subgroup analyses, the factors of "the time from symptoms to debridement was < 3 weeks" and "the bacterial species other than methicillin-resistant Staphylococcus aureus" significantly improved the success rate of DAIR and thus were defined as the major criteria. The statistically insignificant factors of "the open debridement and liner exchange" and "the comorbidity of rheumatoid arthritis" were set as the minor criteria. The success rate of DAIR for PKI meeting all the major criteria and no less than one minor criterion was 80.98%, which was significantly higher than the overall success rate of DAIR (p < 0.05). CONCLUSION: PKI cases meeting two major criteria and no less than one minor criterion may confer a high success rate of DAIR. This simple algorithm may contribute to identifying the appropriate PKI patient for DAIR treatment and predicting the prognosis of DAIR.
78Periprosthetic joint infection in unicompartmental knee arthroplasty: treatment options and outcomes. What is the current evidence in literature?PubMed
Andrea Zanirato, Luca Cavagnaro, Francesco Chiarlone, et al.
Arch Orthop Trauma Surg. 2023 Feb;143(2):1031-1039. doi: 10.1007/s00402-022-04414-4. Epub 2022 Mar 18.
INTRODUCTION: Periprosthetic joint infections (PJI) following unicompartmental knee arthroplasties (UKAs) will increase. The aim of this review is to evaluate current evidence regarding treatment options, complications, clinical and radiological outcomes of PJI management in UKAs. METHODS: A systematic review of English literature was performed. Retrospective and prospective studies providing treatment options, complications, clinical and radiological outcomes of PJI following UKAs were included. PJI type, treatment, survival rate with no reoperation for infection and survival rate with no reoperation for any cause were evaluated. RESULTS: Eleven articles were included. Three studies focusing on PJI following UKA (45 cases) report a survival rate with no reoperation for infection of 68.9% and a survival rate with no reoperation for any cause of 48.9%. Eight articles concerning UKA failure modes (28 cases) overestimate survival rate with no reoperation for infection (88.9%) and survival rate with no reoperation for any cause (88.9%) (p < 0.05). DAIR reports a rate of infection eradication failure ranging from 43.8 to 100%. 1SE allows for a survival rate with no reoperation for infection of 100%. 2SE reports a rate of infection eradication failure ranging from 0 to 12.5%. A high rate of early aseptic reoperation is reported, despite infection eradication (20% in DAIR; 28.5% in 2SE). CONCLUSIONS: Treatment strategy is determined by symptom timing, PJI type (acute vs chronic), causative organism, patient's comorbidities. A longer duration of PJI or severe host and extremity status seems to require 2SE or 1SE. Patients who have a shorter duration of PJI could receive DAIR.
79Microbiological profiles in periprosthetic joint infections after total knee arthroplasty: a comparative analysis of diabetic and non-diabetic patients.PubMed
Musa Ergin, Maximilian Budin, Sebati Başer Canbaz, et al.
Int Orthop. 2024 Oct;48(10):2633-2640. doi: 10.1007/s00264-024-06275-5. Epub 2024 Aug 24.
AIM OF THE STUDY: The purpose of this study is to conduct a comparative analysis of the microbiological profiles in periprosthetic joint infections (PJIs) after total knee arthroplasty (TKA) between diabetic and non-diabetic patients. The study aims to address what are the variations in microbial colonization and infection patterns between diabetic and non-diabetic patients undergoing total knee arthroplasty. METHODS: A retrospective analysis of 2,569 culture-positive cases of PJIs post-TKA was conducted, comparing outcomes between diabetic (n = 321) and non-diabetic (n = 2,248) patients. Demographic, clinical, and microbiological data were collected and analyzed using descriptive statistics, chi-squared tests, logistic regression, and other statistical tests. RESULTS: Diabetic patients exhibited distinct microbial colonization patterns, with a higher prevalence of pathogens such as Staphylococcus aureus (p = 0.033), Pseudomonas aeruginosa (p < 0.001), Streptococcus spp. (Streptococcus agalactiae and Streptococcus dysgalactiae; p = 0.010, 0.016 respectively), Candida spp. (p = 0.010), and Corynebacterium spp. (p = 0.024). Additionally, diabetic patients were at increased risk of polymicrobial infections. Comorbidities associated with diabetes, including chronic pulmonary disease, renal insufficiency, and peripheral artery disease, were significantly more prevalent in diabetic patients and further complicated PJI outcomes. CONCLUSION: This study underscores the importance of tailored perioperative antimicrobial strategies and vigilant infection control measures in diabetic patients undergoing TKA. Understanding the differential microbial profiles and associated comorbidities can inform targeted interventions to mitigate the risk of PJIs and improve outcomes in this high-risk population. Further research is warranted to elucidate the underlying mechanisms and optimize management strategies for diabetic patients undergoing TKA.
80Efficacy of DAIR in managing Candida parapsilosis-infected total knee arthroplasty with five-year follow-up: A case report and review of literature.PubMed
Menglong Li, Mingrui Fan, Yuchen Zhang, et al.
Medicine (Baltimore). 2023 Nov 24;102(47):e36246. doi: 10.1097/MD.0000000000036246.
RATIONALE: Fungal periprosthetic joint infections (fPJIs) are relatively uncommon, accounting for approximately 1% of all PJIs. Revision surgery is typically recommended for fungal infections; however, the physical and financial impact on patients is significant. In this report, we present a case of fPJI successfully treated with debridement, antibiotics, and implant retention (DAIR) with a favorable outcome over a 5-year period. PATIENT CONCERN: A 56-year-old male patient presented with a non-healing surgical incision 1 week after undergoing primary total knee arthroplasty on the right side. DIAGNOSIS: Microbiological culture of the wound effusion identified Candida parapsilosis. Postoperatively, the patient exhibited a significant decrease in serum albumin levels and poor glycemic control. Both C-reactive protein and erythrocyte sedimentation rate were elevated. INTERVENTIONS: A comprehensive DAIR procedure was performed, along with continuous closed irrigation using fluconazole for 1 week. The patient received intravenous voriconazole for 4 weeks, followed by oral fluconazole for an additional 3 months. OUTCOMES: At 1- and 5-year follow-up appointments, the patient C-reactive protein and erythrocyte sedimentation rate levels were within normal limits, and there was no evidence of swelling, erythema, or tenderness in the right knee joint, indicating no signs of infection. LESSONS: DAIR is an effective treatment for early fPJIs, and continuous closed irrigation may provide specific advantages. The patient nutritional status plays a crucial role in the management of periprosthetic infections.
81Salvage procedure for chronic periprosthetic knee infection: the application of DAIR results in better remission rates and infection-free survivorship when used with topical degradable calcium-based antibiotics.PubMed
Y Gramlich, T Johnson, M Kemmerer, et al.
Knee Surg Sports Traumatol Arthrosc. 2020 Sep;28(9):2823-2834. doi: 10.1007/s00167-019-05627-8. Epub 2019 Jul 18.
PURPOSE: Debridement, systemic antibiotics and implant retention (DAIR) is very successful for early periprosthetic joint infection (PJI), but can fail in late-onset cases. We selected patients with PJI who were unsuitable for two-stage exchange total knee arthroplasty (TKA) and compared the outcomes of DAIR with or without degradable calcium-based antibiotics. METHODS: All patients fulfilled the criteria for late-onset PJI of TKA, as defined by an International Consensus Meeting in 2013, but were unsuitable for multistage procedures and TKA exchange due to operative risk. Fifty-six patients (mean age: 70.6 years, SD ± 10.8), in two historical collectives, were treated using a single-stage algorithm consisting of DAIR without antibiotics (control group, n = 33, 2012-2014), or by DAIR following the implantation of degradable antibiotics as indicated by an antibiogram (intervention group, n = 23, 2014-2017). OSTEOSET (admixed vancomycin/tobramycin), and HERAFILL-gentamicin were used as carrier systems. The primary endpoint was re-infection or surgical intervention after DAIR. RESULTS: There were no significant differences between the two groups in terms of mean age, Charlson comorbidity index or the rate of mixed infections. Overall, 65.2% of patients achieved remission in the intervention group compared with only 18.2% in the control group (p < 0.001); 50% of re-infections in the intervention group even occurred after 36 months. Kaplan-Meier analysis showed that, compared with controls, the intervention group experienced significantly longer 3-year infection-free survival. CONCLUSION: DAIR shows poor efficacy in difficult-to-treat cases, as demonstrated in our control group, which had a re-infection rate of 81.8%. In contrast, a DAIR group receiving topical calcium-based antibiotics showed significantly higher 3-year infection-free survival. Therefore, the combination of DAIR and degradable antibiogram-based local antibiotics is a reasonable salvage procedure for this body of patients. This is important as the number of severely sick patients who are too old for appropriate PJI treatment is estimated to increase significantly due to demographic change.
82Impact of a Novel Antiseptic Lavage Solution on Acute Periprosthetic Joint Infection in Hip and Knee Arthroplasty.PubMed
Luca Andriollo, Rudy Sangaletti, Calogero Velluto, et al.
J Clin Med. 2024 May 24;13(11):3092. doi: 10.3390/jcm13113092.
Periprosthetic joint infection (PJI) represents a challenge following hip or knee arthroplasty, demanding immediate intervention to prevent implant failure and systemic issues. Bacterial biofilm development on orthopedic devices worsens PJI severity, resulting in recurrent hospitalizations and significant economic burdens. The objective of this retrospective cohort study is to evaluate the efficacy of this novel antiseptic solution, never previously evaluated in vivo, in managing early post-operative or acute hematogenous PJI following primary hip and knee joint replacements. The inclusion criteria consist of patients with total hip arthroplasty (THA) or knee arthroplasty diagnosed with acute PJI through preoperative and intraoperative investigations, in accordance with the MSIS ICM 2018 criteria. The minimum required follow-up was 12 months from the cessation of antibiotic therapy. This novel antiseptic lavage solution is composed of ethanol, acetic acid, sodium acetate, benzalkonium chloride and water. Data included demographic characteristics, diagnostic criteria, surgical techniques, post-operative treatment and follow-up outcomes. A total of 39 patients treated with Debridement, Antibiotics Pearls and Retention of the Implant (DAPRI) procedures using this solution between May 2021 and April 2023 were analyzed. At a mean follow-up of 24.6 ± 6.4 months, infection recurrence-free survival rates were 87.2%, with no local allergic reactions or relevant systemic adverse effects detected. Persistent PJI necessitated two-stage revision surgery. This novel antiseptic lavage solution shows promise as an adjunctive tool in the treatment of PJI, demonstrating support in infection control while maintaining a favorable safety profile.
83Preliminary clinical results of coated porous tibia cones in septic and aseptic revision knee arthroplasty.PubMed
Malte Ohlmeier, Christian Lausmann, Matthias Wolff, et al.
Arch Orthop Trauma Surg. 2021 Apr;141(4):555-560. doi: 10.1007/s00402-020-03434-2. Epub 2020 Apr 9.
PURPOSE: To analyze the first results of calcium-phosphate-coated porous tibia cones. METHODS: Patients treated with TrabecuLink-CaP Cones were retrospectively recruited from January 2016 to December 2017. These custom-made cones were produced using titanium alloy Ti-6Al-4 V (Tilastan) and using additive manufacturing with a special calcium-phosphate coating (HX-coating). Clinical outcome was evaluated using Oxford Knee Score. For radiological evaluation of the implants, patients sent us outpatient taken radiographs. A minimum follow-up of one year was required. Lastly, we analyzed postoperative complications and revision rates. RESULTS: 52 patients with revision knee arthroplasty (RKA) were recruited for final analysis, of whom, we had 17 septic RKAs (33%) and 35 aseptic cases of RKA (67%). The bone defects were grouped into 17 AORI Type 2A (32.7%), 14 Type 2B (26.9%) and 21 Type 3 (40.4%). After a mean follow-up of 22 months (13.2-34.8; SD = ± 10), we had 4 surgical revisions (7.7%), 2 septic and 2 aseptic cases. The mean Oxford Knee Score was 28.6 points (8-47; SD = ± 10). 22 of 28 radiographs (78.6%) showed regular positioning of the cones and TKAs at a mean follow-up of 16.8 months (13.2-34.8; SD = ± 6). Three patients (10.7%) showed slight radiolucencies in the bone-cement interfaces and 3 patients (10.7%) had beginning heterotopic ossifications. CONCLUSIONS: This study shows the initial clinical results of calcium-phosphate-coated tibia cones showing a good functional outcome. Further research should focus on long-term clinical and radiological follow-up.
84The influence of tibial component fixation techniques on resorption of supporting bone stock after total knee replacement.PubMed
Desmond Y R Chong, Ulrich N Hansen, Rene van der Venne, et al.
J Biomech. 2011 Mar 15;44(5):948-54. doi: 10.1016/j.jbiomech.2010.11.026. Epub 2011 Jan 14.
Periprosthetic bone resorption after tibial prosthesis implantation remains a concern for long-term fixation performance. The fixation techniques may inherently aggravate the "stress-shielding" effect of the implant, leading to weakened bone foundation. In this study, two cemented tibial fixation cases (fully cemented and hybrid cementing with cement applied under the tibial tray leaving the stem uncemented) and three cementless cases relying on bony ingrowth (no, partial and fully ingrown) were modelled using the finite element method with a strain-adaptive remodelling theory incorporated to predict the change in the bone apparent density after prosthesis implantation. When the models were loaded with physiological knee joint loads, the predicted patterns of bone resorption correlated well with reported densitometry results. The modelling results showed that the firm anchorage fixation formed between the prosthesis and the bone for the fully cemented and fully ingrown cases greatly increased the amount of proximal bone resorption. Bone resorption in tibial fixations with a less secure anchorage (hybrid cementing, partial and no ingrowth) occurred at almost half the rate of the changes around the fixations with a firm anchorage. The results suggested that the hybrid cementing fixation or the cementless fixation with partial bony ingrowth (into the porous-coated prosthesis surface) is preferred for preserving proximal tibial bone stock, which should help to maintain post-operative fixation stability. Specifically, the hybrid cementing fixation induced the least amount of bone resorption.
85Do Metaphyseal Cones and Stems Provide Any Biomechanical Advantage for Moderate Contained Tibial Defects in Revision TKA? A Finite-Element Analysis Based on a Cadaver Model.PubMed
Fernando J Quevedo González, Kathleen N Meyers, Nicholas Schraut, et al.
Clin Orthop Relat Res. 2021 Nov 1;479(11):2534-2546. doi: 10.1097/CORR.0000000000001912.
BACKGROUND: Satisfactory management of bone defects is important to achieve an adequate reconstruction in revision TKA. Metaphyseal cones to address such defects in the proximal tibia are increasingly being used; however, the biomechanical superiority of cones over traditional techniques like fully cementing the implant into the defect has not yet been demonstrated. Moreover, although long stems are often used to bypass the defects, the biomechanical efficacy of long stems compared with short, cemented stems when combined with metaphyseal cones remains unclear. QUESTIONS/PURPOSES: We developed and validated finite-element models of nine cadaveric specimens to determine: (1) whether using cones for addressing moderate metaphyseal tibial defects in revision TKA reduces the risk of implant-cement debonding compared with cementing the implant alone, and (2) when using metaphyseal cones, whether long, uncemented stems (or diaphyseal-engaging stems) reduce the risk of implant-cement debonding and the cone-bone micromotions compared with short, cemented stems. METHODS: We divided nine cadaveric specimens (six male, three female, aged 57 to 73 years, BMI 24 to 47 kg/m2) with standardized tibial metaphyseal defects into three study groups: no cone with short (50-mm) cemented stem, in which the defect was filled with cement; cone with short (50-mm) cemented stem, in which a metaphyseal cone was implanted before cementing the implant; and cone with long, diaphyseal-engaging stem, which received a metaphyseal cone and the largest 150-mm stem that could fit the diaphyseal canal. The specimens were implanted and mechanically tested. Then, we developed and validated finite-element models to investigate the interaction between the implant and the bone during the demanding activity of stair ascent. We quantified the risk of implant debonding from the cement mantle by comparing the axial and shear stress at the cement-implant interface against an experimentally derived interface failure index criterion that has been previously used to quantify the risk of cement debonding. We considered the risk of debonding to be minimal when the failure index was below 10% of the strength of the interface (or failure index < 0.1). We also quantified the micromotion between the cone and the bone, as a guide to the likelihood of fixation by bone ingrowth. To this end, we assumed bone ingrowth for micromotion values below the most restrictive reported threshold for bone ingrowth, 20 µm. RESULTS: When using a short, 50-mm cemented stem and cement alone to fill the defect, 77% to 86% of the cement-implant interface had minimal risk of debonding (failure index < 0.1). When using a short, 50-mm cemented stem with a cone, 87% to 93% of the cement-implant interface had minimal debonding risk. When combining a cone with a long (150-mm) uncemented stem, 92% to 94% of the cement-implant interface had minimal debonding risk. The differences in cone-bone micromotion between short, cemented stems and long, uncemented stems were minimal and, for both configurations, most cones had micromotions below the most restrictive 20-µm threshold for ingrowth. However, the maximum micromotion between the cone and the bone was in general smaller when using a long, uncemented stem (13-23 µm) than when using a short, cemented stem (11-31 µm). CONCLUSION: Although the risk of debonding was low in all cases, metaphyseal cones help reduce the biomechanical burden on the implant-cement interface of short-stemmed implants in high-demand activities such as stair ascent. When using cones in revision TKA, long, diaphyseal-engaging stems did not provide a clear biomechanical advantage over short stems. Future studies should explore additional loading conditions, quantify the interspecimen variability, consider more critical defects, and evaluate the behavior of the reconstructive techniques under repetitive loads. CLINICAL RELEVANCE: Cones and stems are routinely used to address tibial defects in revision TKA. Despite our finding that metaphyseal cones may help reduce the risk of implant-cement debonding and allow using shorter stems with comparable biomechanical behavior to longer stems, either cones or cement alone can provide comparable results in contained metaphyseal defects. However, longer term clinical studies are needed to compare these techniques over time.
86Validation and sensitivity of model-predicted proximal tibial displacement and tray micromotion in cementless total knee arthroplasty under physiological loading conditions.PubMed
Huizhou Yang, Riza Bayoglu, Mohsen Sharifi Renani, et al.
J Mech Behav Biomed Mater. 2020 Sep;109:103793. doi: 10.1016/j.jmbbm.2020.103793. Epub 2020 Apr 21.
The initial fixation of cementless tibial trays after total knee arthroplasty is crucial to bony ingrowth onto the porous surface of the implants, as micromotion magnitudes exceeding 150 μm may inhibit bone formations and limit fixation. Experimental measurement of the interface micromotions is still very challenging. Thus, previous studies investigated micromotions at the bone-tray interface via finite element methods, but few performed direct validation via in vitro cadaveric testing under physiological loading conditions. Additionally, previous models were validated by solely considering relative displacements of the marker couples placed around the tray-bone interface. In this paper, we present an experimental-computational validation framework for investigating micromotions at the tray-bone interface under physiological conditions. Three cadaveric specimens were implanted with cementless rotating-platform implants and tested under gait, deep knee bending, and stair descent loads. Corresponding subject-specific finite element models were developed and used to predict the marker (tray-bone) relative displacements and tibial surface displacements. Experimental measurements were used to validate model estimations. Subsequent sensitivity analyses were performed on implantation and friction parameters to represent model uncertainties. The models appropriately differentiated between locations, activities, and specimens. The average root-mean-square (RMS) differences and correlations between measured marker relative displacements and predictions from the 'best-matching' models were 13.1 μm and 0.86. RMS differences and correlations between measured surface displacements and predictions were 78.9 μm and 0.84. Full-field interface micromotions were investigated and compared with predicted marker relative displacements. The marker relative displacements underestimated the actual interface micromotions. Initial tray-bone alignment in anterior-posterior, flexion-extension, and varus-valgus degrees of freedom have a considerable impact on the interface micromotions. The validated cadaveric models can be further used for pre-clinical assessments of new TKR tray design. The outcomes of the sensitivity analyses provide further insights into reducing interface micromotions via clinical techniques.
87Utilizing 3d-printed patient-specific porous titanium cones in complex primary and revision total knee arthroplasty.PubMed
Arash Sharafat Vaziri, Ghazaleh Moradkhani, Farzam Farahmand, et al.
Eur J Orthop Surg Traumatol. 2025 Mar 6;35(1):96. doi: 10.1007/s00590-025-04229-0.
INTRODUCTION: Effective management of bone defects is crucial in revision total knee arthroplasty (rTKA) to ensure implant stability in low-density bone environments, especially following prosthesis removal. While various reinforcement techniques exist, such as allografts, augments, metal cones, sleeves, or combinations thereof, metal cones are increasingly favored for their ability to reconstruct significant bone defects. A prominent challenge with off-the-shelf (OTS) cones is their unsuitability for Asian and specifically Iranian anatomies due to mismatched sizes and smaller medullary canals. This study explores the application of customized 3D-printed porous titanium cones, tailored to individual patient anatomy, for bone defect reconstruction in complex primary or revision total knee arthroplasty (TKA). MATERIALS AND METHODS: Utilizing CT scans for 3D preoperative planning, porous cones were individually designed to fit each patient's anatomy. A novel aspect of these cones is their dual functionality: promoting bone ingrowth while preventing cement infiltration. The cones were fabricated using selective laser melting with medical-grade Ti6Al4V alloy. To aid in surgical preparation, single-use polyamide trials were also 3D-printed. RESULTS: A total of nineteen cones/half cones (four diaphyseal, twelve metaphyseal, and three meta-diaphyseal) for femoral and tibial applications were successfully designed and implanted across ten cases. There was a perfect alignment between preoperative planning and intraoperative outcomes, with precise defect reconstruction achieved in all cases. Early follow-ups indicated no loosening or implant migration. CONCLUSIONS: Customized patient-specific porous cones offer not only the long-term benefits of OTS options, such as osseointegration and biological fixation but also accurately address a wide range of complex metaphyseal and diaphyseal defects. This approach preserves residual bone stock and streamlines the surgical process, presenting a promising advancement in bone defect management in rTKA.
88Cementless total knee arthroplasty in patients with inflammatory arthritis and compromised bone.PubMed
S A Stuchin, M Ruoff, W Matarese
Clin Orthop Relat Res. 1991 Dec(273):42-51.
Patients with bone compromised by inflammatory arthritis and medications are often excluded from cementless total knee arthroplasty (TKA) because of concerns regarding implant fixation and ingrowth. However, many such patients are young and at long-term risk for implant failure no matter what the fixation technique. Improved implant designs and technique may improve results. Cementless arthroplasty was performed in 45 patients with inflammatory arthritis. There were 38 patients with 53 implants available for follow-up evaluation during a 2- to 6.4-year period (average, 3.3 years). Medications included steroids (16 patients), nonsteroidal antiinflammatory drugs (36 patients), and cytotoxic agents (12 patients). Twenty-nine patients were using at least two types of medication. Prostheses included the Tricon P, Tricon M, Miller-Galante, and Anatomic Modular Knee (AMK) prosthesis. The procedures were performed using standard ligament-balancing techniques. Tibial resections were within 1 cm of the tibial plateau, thereby necessitating extensive bone grafts in ten patients. Tibial components were chosen for maximal cortical rim contact. Roentgenograms were reviewed for alignment, tibial rim contact, radiolucencies, gaps, sclerosis, and subsidence. Patients with no evidence of gap or lucency had spot films under image control. Hospital for Special Surgery knee scores averaged 47 preoperatively and 88 at follow-up examination. Alignment was from 3 degrees valgus to 9 degrees valgus (average, 6 degrees valgus), with a tibial axis of 0 degrees +/- 2 degrees. Plateau coverage was within 2.4 mm (average) of the cortical rim in all planes in the anteroposterior (AP) and lateral views. Tibial sclerosis occurred with equal frequency in all AP zones and was present equally in anterior and posterolateral zones. Gaps and lucencies were more common laterally. Fifteen femoral components showed a disturbing, localized osteopenia. Sclerosis, gap, and lucency were most common anteriorly. Cementless TKA with appropriate technique can produce results comparable to cemented surgery in patients with bone quality compromised by inflammatory arthritis, steroids, and nonsteroidal and cytotoxic agents. The femoral bone response suggests an intimate bone implant relationship. The tibia shows little direct coupling of prosthesis to bone. These responses are similar to reports from other studies. Fixation is sufficient to allow for continued analysis over time and results are encouraging.
89Reliability and precision of single frequency bioelectrical impedance assessment of lower extremity swelling following total knee arthroplasty.PubMed
Brian J Loyd, Kristine Burrows, Jeri E Forster, et al.
Physiother Theory Pract. 2021 Jan;37(1):197-203. doi: 10.1080/09593985.2019.1619886. Epub 2019 May 29.
Total knee arthroplasty (TKA) is the most common elective orthopedic surgery performed in the United States. Following surgery patients experience significant lower extremity swelling that is related to poor satisfaction with surgery and is hypothesized to contribute to functional decline. However, in practice, precise and reliable methods for measuring lower extremity swelling do not exist. The purpose of this study was to provide reliability and precision parameters of an innovative approach, single frequency bioelectrical impedance assessment (SF-BIA), for measuring post-TKA lower extremity swelling. Swelling in 56 patients (64.3 ± 9.3 years; 29 males) was measured before and after TKA using SF-BIA and circumferential measures (CM). Reliability of the measures was calculated using Intraclass Correlation Coefficients (ICC). Precision of the measures was provided using standard error of the measurement and minimal detectable change (MDC90). Change values between time points for SF-BIA and CM are provided. SF-BIA was found to have greater reliability following surgery compared to CM (ICC = 0.99 vs 0.68). SF-BIA was found to have an MDC90 = 2% following surgery, indicating improved ability to detect minute fluctuations in swelling compared to CM (MDC90 = 6%) following surgery. These results indicate that SF-BIA improves the precision and reliability of swelling measurement compared to CM.
90The relationship between lower extremity swelling, quadriceps strength, and functional performance following total knee arthroplasty.PubMed
Brian J Loyd, Scott Stackhouse, Michael Dayton, et al.
Knee. 2019 Mar;26(2):382-391. doi: 10.1016/j.knee.2019.01.012. Epub 2019 Feb 14.
BACKGROUND: The relationships between swelling after total knee arthroplasty (TKA) and quadriceps strength and functional performance are poorly understood. Therefore, the aim of this study was to examine the relationships between lower extremity swelling, measured using bioelectrical impedance assessment (SF-BIA), and quadriceps strength and timed up and go (TUG) times following TKA. METHODS: 53 participants (64 ± 9.5 y/o, 43% male) undergoing primary unilateral TKA were recruited for the longitudinal observational study with repeated measures. Quantities of swelling were examined for contribution to two and six-week outcomes of strength and TUG time using hierarchical regression controlling for age, sex, and the baseline value of the dependent variable. Swelling was assessed using bioelectrical impedance assessment and quantified as the peak level of swelling and cumulative swelling (integral) over the post-TKA time window. Maximum isometric quadriceps strength (MVIC) was measured using a electromechanical dynamometer and participant functional performance measured using the TUG. RESULTS: Neither peak swelling nor cumulative swelling significantly contributed to the variance of two-week quadriceps strength. At six weeks, peak swelling significantly improved the variance in maximal quadriceps strength by an additional four percent (p = 0.05), while cumulative swelling did not significantly contribute. Peak swelling significantly contributed to the variance in two-week (16%) and six-week (five percent) TUG times (p < 0.05), but the cumulative swelling did not. CONCLUSIONS: Peak swelling represents a value of post-TKA swelling that is associated with strength and function. Reducing the peak level of swelling, occurring early after surgery, may improve patient functional recovery. LEVEL OF EVIDENCE: Level II - Prospective observational study.
91Bioimpedance spectroscopy for swelling evaluation following total knee arthroplasty: a validation study.PubMed
Claude Pichonnaz, Jean-Philippe Bassin, Estelle Lécureux, et al.
BMC Musculoskelet Disord. 2015 Apr 25;16:100. doi: 10.1186/s12891-015-0559-5.
BACKGROUND: The evaluation of swelling is important for the outcome of total knee arthroplasty (TKA) surgery. The circumference or volume measurements are applicable at the bedside of the patient but are altered by muscular atrophy and the post-surgical dressing. Bioimpedance spectroscopy might overcome these limitations; however, it should be validated. This study aimed to explore the validity, the reliability and the responsiveness of bioimpedance spectroscopy for measuring swelling after TKA. METHODS: The degree of swelling in 25 patients undergoing TKA surgery was measured using bioimpedance spectroscopy (BIS R0), knee circumference and limb volume. The measurements were performed on D-1 (day before surgery), D + 2 (2 days after surgery) and D + 8 (8 days after surgery). The BIS R0 measurements were repeated twice, alternating between two evaluators. The percentage of the difference between the limbs was calculated for BIS R0, circumference and volume. The intra- and inter-observer intraclass correlation coefficients (ICCs), limits of agreement (LOA), effect size (Cohen's d), correlations between the methods and diagnostic sensitivity were calculated. RESULTS: BIS R0, circumference and volume detected swelling < 3.5% at D-1. The swelling at D2 and D8 was greater with BIS R0 [mean (SD) 29.9% (±9.8) and 38.27 (±7.8)] than with volume [14.7 (±9.5) and 14.9 (±8.2)] and circumference [11.1 (±5.7) and 11.7 (±4.1)]. The BIS R0 intra- and inter-evaluator ICCs ranged from 0.89 to 0.99, whereas the LOA were < 5.2%. The BIS R0 correlation was 0.73 with volume and 0.75 with circumference. The BIS R0 Cohen's d was 3.32 for the D-1-D2 evolution. The diagnostic sensitivity was 83% D2 and 96% at D8. CONCLUSION: Bioimpedance is a valid method for the evaluation of swelling following TKA. BIS R0 also demonstrated excellent intra- and inter-evaluator reliability. The diagnostic sensitivity and responsiveness is superior to that of concurrent methods. BIS R0 is an efficient method for post-surgical follow up at the bedside of the patient. The measurement of BIS R0 is a straightforward, valid, reliable and responsive method for lower limb swelling following TKA surgery that could be used in clinics and research. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00627770.
92Development of a reference chart to monitor postoperative swelling following total knee arthroplasty.PubMed
Brian J Loyd, Andrew J Kittelson, Jeri Forster, et al.
Disabil Rehabil. 2020 Jun;42(12):1767-1774. doi: 10.1080/09638288.2018.1534005. Epub 2019 Jan 22.
Development of a reference chart to monitor postoperative swelling following total knee arthroplasty. Lower extremity swelling is a feature of total knee arthroplasty. Until recently, clinicians lacked tools to accurately measure swelling in clinical settings, but bioelectrical impedance assessment has shown promise in this regard. The purpose of this study was to develop a reference chart of lower extremity swelling following total knee arthroplasty. Fifty-six participants (54% male, mean age = 64 years) were followed for the first 7 weeks following total knee arthroplasty, during which frequent lower extremity bioelectrical impedance assessments were performed. Using Generalized Additive Models for Location Scale and Shape, a reference chart for swelling was developed with bioelectrical impedance assessment data from the first 40 patients enrolled in the study (223 observations) and preliminarily tested for performance in the remaining 16 patients' data (96 observations). The reference chart illustrates approximately 10% per day increase for the first 3 days following surgery. Peak swelling occurs 6-8 days following surgery; the 10th percentile demonstrates a peak of 25%, whereas the 90th percentile peaks at 47%. In the test data, this reference chart demonstrated accurate coverage at each estimated centile. The reference chart provides a novel framework for monitoring swelling following total knee arthroplasty and may augment clinical decisions to improve postoperative swelling management.Implications for rehabilitationThe use of bioelectrical impedance assessment provides an accurate and easily implemented approach for rehabilitation professionals to measure swelling.The reference chart provided allows for monitoring of patient recovery of swelling following total knee arthroplasty.Precise depictions of where a patient's swelling is in reference to others will improve clinical decision making at the individual level.
93Swelling assessment after total knee arthroplasty.PubMed
Li Ka Yau, F U Henry, Cheung Man Hong, et al.
J Orthop Surg (Hong Kong). 2022 Sep-Dec;30(3):10225536221127668. doi: 10.1177/10225536221127668.
BACKGROUND: Total knee arthroplasty is a commonly performed elective orthopaedic surgery. Patients may endure substantial knee swelling following surgery, which are attributable to both effusion and edema. Studies have been aiming to identify an accurate and reliable method to quantify post-operative knee swelling to aid monitoring progress and treatment. The aim of this article was to review the means of clinically applicable measurements for knee swelling post TKA. METHODS: The medical literature was searched using PubMed to search for articles published using the terms knee edema, effusion, swelling, knee arthroplasty, knee replacement, total knee arthroplasty, total knee replacement, TKA, TKR. Year of publication was not restricted. Only English language publications were included. Only full-text published articles from peer-reviewed journals were eligible for inclusion. The knee swelling measurement methods used in post TKA were reviewed. RESULTS: Advancement in bioimpedance spectroscopy and handheld 3D scanning technology allows quick and precise quantification of knee swelling volume that the traditional clinical circumferential measurement and volumetric measurement lack. Handheld 3D scanning is also a potential tool to estimate the change of knee effusion volume and muscular volume after the surgery. Magnetic resonance imaging is accurate in effusion measurement but also the most time and resource demanding method. CONCLUSION: Bioimpedance spectroscopy and 3D scanning technology can be the future tools for clinically measurement of knee swelling after total knee arthroplasty.
94Unicompartmental Knee Arthroplasty: Indications, Outcomes, and Complications.PubMed
Vineet Tyagi, Mohammad Farooq
Conn Med. 2017 Feb;81(2):87-90.
Unicompartmental knee arthroplasty (UKA) is a surgical option which is indicated in a special subset of osteoarthritis patients. Although it is often technically challenging, out-comes are positive when indications are followed as operative criteria. Benefits compared to total knee arthroplasty (TKA) include lower morbidity and a shorter recovery time. Potential complications include dislocation of the mobile-bearing surface, prosthesis loosening, and periprosthetic fracture. Revision surgery often involves a conversion to TKA, with outcomes comparable to revisions after TKA. 'he purpose of this review is to summarize the indications, outcomes, and complications of UKA, as well as the clinical outcomes after revision procedures.
95Outcomes and complications of unicondylar arthroplasty.PubMed
Andrew J Riff, Alexander P Sah, Craig J Della Valle
Clin Sports Med. 2014 Jan;33(1):149-60. doi: 10.1016/j.csm.2013.06.005. Epub 2013 Aug 28.
Unicompartmental knee arthroplasty has experienced resurgence in popularity because of the lower morbidity of the procedure and the proposed benefits over total knee replacement in appropriately selected patients. Improved component designs and advanced surgical techniques have promoted excellent results. Expanded indications to include the very young and the elderly have yielded comparable clinical outcomes. Nonetheless, the success of unicompartmental replacement depends on proper surgical technique and patient selection. Distinct surgical considerations exist depending on whether the medial, lateral, or patellofemoral compartment is replaced. Long-term studies have shown that unicompartmental knee replacement is an alternative to total knee arthroplasty.
96Medial Unicompartmental Knee Arthroplasty.PubMed
Andrew Barrister Richardson, Michael J Morris
Instr Course Lect. 2017 Feb 15;66:201-209.
Unicompartmental knee arthroplasty (UKA) has substantial benefits, including lower perioperative morbidity and earlier recovery, compared with total knee arthroplasty. The traditionally strict indications for UKA have been challenged by studies that expanded the indications based on a diagnosis of anteromedial osteoarthritis of the knee and demonstrated successful outcomes. The Nuffield criteria no longer prohibit patients from UKA based on age, obesity, anterior knee pain, or involvement of the patellofemoral joint. UKA implant designs have evolved substantially in the past three decades, and both fixed- and mobile-bearing UKA implants are currently available. Both fixed- and mobile-bearing UKA implants demonstrate excellent clinical outcomes at more than 10 years postoperatively but continue to have different modes of long-term implant failure. Proper patient selection and execution of surgical technique are critical to optimize patient outcomes.
97Indications, outcomes, and complications of unicompartmental knee arthroplasty.PubMed
Liyang Chen, Wenqing Liang, Xiaoping Zhang, et al.
Front Biosci (Landmark Ed). 2015 Jan 1;20(4):689-704. doi: 10.2741/4330.
Improved prosthetic design and application of strict criteria in selection of patients have resulted in wide use of unicompartmental knee arthroplasty (UKA) in surgical treatment of damaged joints. Here, we review the contemporary indications, outcomes, and complications of procedures such as lateral and medial UKA and total knee arthroplasty (TKA), and compare the severity of these complications in UKA and TKA. Patients who received unicompartmental femorotibial osteoarthritis and patients who underwent UKA and ACL reconstruction for deficiency in anterior cruciate ligament (ACL), they all showed good clinical outcomes and survival. Reliable and successful options in the treatment of patients with isolated tibiofemoral osteoarthritis include lateral and medial UKA.
98A Matched Comparison of Long-Term Outcomes of Total and Unicompartmental Knee Replacements in Different Ages Based on National Databases: Analysis of Data From the National Joint Registry for England, Wales, Northern Ireland, and the Isle of Man.PubMed
Hasan R Mohammad, Alexander D Liddle, Andrew Judge, et al.
J Arthroplasty. 2022 Feb;37(2):243-251. doi: 10.1016/j.arth.2021.09.018. Epub 2021 Oct 5.
BACKGROUND: The 2 main treatment options for end-stage single compartment knee arthritis are unicompartmental (UKR) or total knee replacement (TKR). We compared the long-term outcomes in different age groups. METHODS: In total, 54,215 UKRs and 54,215 TKRs from the National Joint Registry and Hospital Episode Statistics database were propensity score matched and Kaplan-Meier and regression analysis used to compare revision, reoperation, mortality, and 3-month complications. RESULTS: UKR had higher 10-year revision rates (12% vs 5%, hazard ratio [HR] 2.31, P < .001) and 10-year reoperation rates (25% vs 21%, HR 1.12, P < .001). UKR had lower 10-year mortality rates (13.6% vs 15.5%, HR 0.86, P < .001). UKR had lower rates of medical (P < .001) and procedure related (P < .001) complications and deaths (HR 0.61, P = .02). If 100 patients had a UKR instead of a TKR then over 10 years, if they were <55 years old there would be 7 more reoperations and 1 less death; if they were 55-64 years old there would be 6 more reoperations and 2 more deaths; if they were 65-74 years old there would be 4 more reoperations and 2 less deaths; and if they were ≥75 years old there would be 3 more reoperations and 4 less deaths. CONCLUSION: UKR has higher revision and slightly higher reoperation rates but lower mortality rates than matched TKR. The decision to do a UKR should, in part, be based on the balance of these risks, which are influenced by patient age. In the elderly group (>75 years) the data suggests that UKR compared to TKR has a greater absolute reduction in mortality than the increase in reoperation rate. LEVELS OF EVIDENCE: III.
99Clinical outcomes of unicompartmental knee arthroplasty and total knee arthroplasty in the same patient.PubMed
Yu Hao, Jia Li, Yamei Feng, et al.
Arch Orthop Trauma Surg. 2024 Nov;144(11):4791-4800. doi: 10.1007/s00402-024-05564-3. Epub 2024 Sep 23.
BACKGROUND: Osteoarthritis has become the predominant manifestation of arthritic conditions on a worldwide scale and serves as a significant instigator of pain, impairment, and increasing socio-economic strain on a global level. The ongoing discourse on the choice between total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) for patients suffering from anterior medial osteoarthritis continues to ignite scholarly controversy. Our objective was to assess and compare the clinical outcomes of UKA and TKA within the same patient, hereby offering a novel perspective on this topic. MATERIALS AND METHODS: Fifty-seven individuals who underwent TKA on one knee and UKA on the other knee at the Department of Orthopaedics, First Hospital of Hebei Medical University between March 2019 and March 2024 were analysed for this retrospective study. We conducted a comprehensive examination and evaluation of perioperative laboratory assessments, radiological examinations, knee functionality, contentment levels, and postoperative complications within the two groups. RESULTS: Following surgical procedures, levels of hemoglobin, red blood cells, and albumin were found to be elevated in the UKA group when compared to the TKA group (hemoglobin: 121.2 ± 12.54 vs. 110.1 ± 13.21 g/L; red blood cells: 4.0 ± 0.47 vs. 3.6 ± 0.42 *10/L; albumin: 37.7 ± 5.66 vs. 35.3 ± 5.23 g/L). There is a significant difference in the hip-knee-ankle angles between the postoperative UKA group and the TKA group (5.3 ± 3.46° vs. 4.1 ± 2.86°, p < 0.05). There existed no notable disparity in postoperative visual analog scale, knee society score, and forgotten joint score between the two groups. However, a remarkable variance was observed in postoperative range of motion between the two groups (116.4 ± 5.96° vs. 108.4 ± 5.32°). CONCLUSION: We found that UKA resulted in less physical strain, less postoperative inflammatory response, improved joint mobility, although with less effective lower limb force line correction compared to TKA. Many patients have shown a preference for UKA and express higher levels of satisfaction with the procedure.
100Clinical Outcomes and Survivorship of Lateral Unicompartmental Knee Arthroplasty: A Large Single Surgeon Cohort.PubMed
William Harkin, Steven Kurina, Alicia Berger, et al.
J Arthroplasty. 2024 Nov;39(11):2702-2707. doi: 10.1016/j.arth.2024.05.067. Epub 2024 May 31.
BACKGROUND: Lateral unicompartmental knee arthroplasty (UKA) is an effective treatment for isolated lateral compartment osteoarthritis. However, due to the rarity of the procedure, long-term outcomes and survivorship are poorly understood. We report the clinical and radiographic outcomes after lateral UKA. METHODS: We retrospectively reviewed a consecutive series of patients who underwent lateral UKA by a single fellowship-trained arthroplasty surgeon from 2001 to 2021 with a minimum 2 year follow up. There were 161 knees in 153 patients (average age 69 years) that met inclusion criteria, with a mean follow up of 10.0 years (range 0.05 to 22.2). All patients underwent the procedure via a minimally invasive lateral parapatellar approach with a fixed-bearing implant. Patient demographics, complications, radiographic findings, patient-reported outcomes, and the need for revision surgery were evaluated. Survivorship was defined with the end point as revision of components. RESULTS: There were 8 patients (5.0%) who underwent conversion to total knee arthroplasty for lateral UKA implant failure or progression of arthritis. There were 3 patients (1.9%) who underwent ipsilateral medial UKA due to medial compartment arthritis progression with preserved mechanical alignment and patellofemoral joint. There were 8 additional procedures that did not require implant changes, including 5 irrigation and debridements for acute periprosthetic joint infection (3.1%), 2 wound closures for dehiscence (1.3%), and one loose body removal (0.6%). CONCLUSIONS: Lateral UKA showed a survivorship rate of 98.0% at 5 years, 96.0% at 10 years, and 94.5% at 15 years. When including patients who underwent additional surgery for the progression of arthritis, survivorship was 97.4% at 5 years, 95.4% at 10 years, and 91.3% at 15 years. Lateral UKA should be seen as a durable treatment option for isolated lateral compartment osteoarthritis.
101Highlighting the advantages and benefits of cementless total knee arthroplasty (Review).PubMed
Bogdan Uivaraseanu, Cosmin Mihai Vesa, Delia Mirela Tit, et al.
Exp Ther Med. 2022 Jan;23(1):58. doi: 10.3892/etm.2021.10980. Epub 2021 Nov 18.
In the field of orthopedic surgery, cemented total knee arthroplasty (TKA) is considered to be one of the gold standards. However, there are categories of patients (i.e., obese and morbidly obese patients, younger than 65 years old) among whom cemented TKA has however a high failure rate. Moreover, the frequency of using uncemented TKA is increasing due to the potential benefits of long-term biological fixation, being an innovative field that addresses a new generation orthopedic surgical treatment which is more suitable for young patients who have good bone quality (good to very good, in terms of density). The survival rates and functional results of the latest generation of cementless TKAs may be similar to functional results and survival rates of cemented prosthesis. In conclusion, this review-type article can be considered a powerful database, extremely informative, dense, and focused on the topic mentioned above, in the interest of all medical professionals and all interested individuals.
102Lower revision rates for cemented fixation in a long-term survival analysis of three different LCS designs.PubMed
Bas van Ooij, Dave R de Keijzer, Daniël Hoornenborg, et al.
Knee Surg Sports Traumatol Arthrosc. 2022 Aug;30(8):2707-2713. doi: 10.1007/s00167-021-06587-8. Epub 2021 May 2.
BACKGROUND: In primary Total Knee Arthroplasty (TKA), it is still not clear if cemented or uncemented fixation has the best long-term survival. The Low Contact Stress (LCS) mobile-bearing (MB) knee system was introduced in 1977. The aim of this study is to investigate the long-term survival of this design with a minimum of 15-year follow-up. METHODS: A retrospective analysis was performed, with the primary endpoint for survival defined as revision. Cox regression analysis was performed to assess the association between type of fixation and the risk of revision, while correcting for potential confounders (diagnosis, design, age and sex). RESULTS: 1271 cases were included with inflammatory joint disease (IJD) (657 cases) and non-IJD (614 cases). TKAs were performed cemented in 522 cases and uncemented in 749 cases. A bicruciate retaining design was used in 180 cases, a rotating platform design in 174 cases and an anterior posterior glide posterior cruciate-retaining (PCR) design in 916 cases. Cumulative incidence of component revision at 15 years was 2.7% (95% CI 1.6; 4.5) for cemented and 10% (95% CI 8.1; 12.4) for uncemented TKA, respectively. The 20-year cumulative incidence was 2.9% (95% CI 1.7; 4.7) for cemented and 10.9% (95% CI 8.8; 13.4) for uncemented TKA, respectively. Age, non-IJD and PCR design were associated with a significantly higher risk of revision, regardless of the type of fixation. CONCLUSION: Long-term survival for patients undergoing cemented or uncemented TKA using the LCS MB system revealed lower revision rates for cemented fixation. Revision risk was higher in younger, non-IJD patients who had the PCR design, regardless of the type of fixation. For the LCS MB TKA design, it is recommended to use cemented fixation.
103Cementless, Cruciate-Retaining Primary Total Knee Arthroplasty Using Conventional Instrumentation: Technical Pearls and Intraoperative Considerations.PubMed
Andrew B Harris, Julius K Oni
JBJS Essent Surg Tech. 2024 Sep 13;14(3). doi: 10.2106/JBJS.ST.23.00036. eCollection 2024 Jul-Sep.
BACKGROUND: Total knee arthroplasty (TKA) is commonly indicated for patients with severe tibiofemoral osteoarthritis in whom nonoperative treatment has failed. TKA is one of the most commonly performed orthopaedic surgical procedures in the United States and is associated with substantial improvements in pain, function, and quality of life. The procedure may be performed with cemented, cementless, or hybrid cemented and cementless components. Cementless TKA utilizing contemporary implant designs has been demonstrated to have excellent long-term survival and outcomes in patients who are appropriately indicated for this procedure. The preference of the senior author is to perform this procedure with use of a cruciate-retaining implant design when feasible, and according to the principles of mechanical alignment to guide osseous resection. It should be noted that nearly all recent studies on outcomes following cementless TKA utilize traditional mechanical alignment. Alternative alignment strategies, such as gap balancing and kinematic alignment, have not been as well studied in cementless TKA; however, preliminary short-term studies suggest comparable survivorship with restricted kinematic alignment and gap balancing compared with mechanical alignment in patients undergoing cementless TKA. DESCRIPTION: Our preferred surgical technique for cementless TKA begins with the patient in the supine position. A thigh tourniquet is applied, and a valgus post is set at the level of the tourniquet. A flexion pad is also placed at 90°, with a bar at 20°. After sterile skin preparation and draping, a time-out is conducted, and the tourniquet is raised. The surgeon makes a medial parapatellar incision, which begins from 1 cm medial to the medial edge of the patella, extending from the tibial tubercle to 2 fingers above the proximal pole of the patella, using a knife and with the knee at 90° of flexion. Scissors are then used to find the fat above the fascia and dissect distally in the same plane. A knife is used to perform a high vastus-splitting, medial parapatellar arthrotomy. Pickups and scissors are then used to perform a partial medial synovectomy, and electrocautery is used to perform a medial peel. As the procedure progresses further medial, the infrapatellar fat pad is excised, followed by the anterior femoral synovial tissue. The surgeon then cuts through the anterior cruciate ligament footprint and origin with the knee flexed before sawing through the tibial spines to decrease the height of the tibial bone block. To prepare the femur, a step drill is inserted into the femoral canal, and the intramedullary alignment guide is placed with the distal femoral cutting guide set to 5° of valgus. The distal femoral cutting guide is then pressed firmly against the distal femur, making sure that the medial side is touching bone, and threaded pins are inserted in the cutting guide under power. The distal femur is then precisely sectioned with use of an oscillating saw equipped with a 21 mm x 90 mm x 1.27-mm saw blade. The surgeon focuses on initiating the cut at the cortices before proceeding further, to avoid cortical blow-out. The resultant cut is meticulously assessed for uniformity and levelness, employing both the alignment rod and the distal cutting guide for verification. Following this assessment, the pins and guide are removed, and any remaining femoral condylar osteophytes are delicately excised with use of a rongeur. The surgeon uses the femoral sizing guide, measures the size of the femur, and double-checks rotation in preparation for the remaining distal femoral cuts. The holes are then drilled to set the rotation for the 4-in-1 cutting guide. When applying the 4-in-1 cutting guide, care is taken to align the guide with the drilled holes in order to avoid inadvertent malrotation. The secure fixation of the block is ensured through the judicious insertion of 2 threaded pins under power at full speed, followed by a more controlled, slower securing process to avoid stripping the threaded pins. Subsequently, the anterior cut is made with the oscillating saw, again with a focus on initiating the cut at the cortices before proceeding further. The posterior cuts are then made in a controlled manner, employing a gentle bouncing technique to facilitate tactile feedback, and keen attention is given to cutting both the medial and lateral cortices of each of the posterior condyles. The anterior chamfer and posterior chamfer are similarly osteotomized. Subsequently, the 4-in-1 cutting guide is gently removed. To complete this phase of the procedure, a curved osteotome and mallet are employed to delicately extract the resected posterior condyles and remove posterior osteophytes as needed. The concave side of the curved osteotome is used with precision to meticulously trace the contours of the condyles, ensuring a precise result. The surgeon places a bump under the knee and extends it to check the medial collateral ligament, quadriceps tendon, patellar tendon, and posterior cruciate ligament to ensure they are intact. To make the tibial cut, the extramedullary alignment guide is placed, and the height of the slot is set to the level of the subchondral bone, aligning the rotation and coronal axis with the 2nd metatarsal. The tibial slope is also set at this step, with the goal of the resection matching the patient's native tibial slope. Matching is usually achieved by visual inspection of the trajectory of the cutting jig, although the stylus can also be utilized to confirm the appropriate tibial slope. The tibial cut is then completed with use of an oscillating saw. A single-sided reciprocating saw is then used to cut perpendicular to the plateau in the medial compartment while making sure not to extend the cut into the unresected portion of the intact tibial plateau. After removal of the medial plateau fragment, a lamina spreader is placed in the medial compartment; this process is repeated with a second cut in a similar fashion in the lateral compartment to create a triangular bone block that fully preserves the insertion of the posterior cruciate ligament. The medial and lateral menisci are resected, and the gaps are checked with use of a spacer block and alignment rod. The surgeon then sizes the tibia and uses their index fingers to feel both medially and laterally for overhang. An alternative approach is to fully expose the tibia in flexion and to size the tibia under complete visualization of the tibial margins. The tibial trial is then pinned in place after ensuring appropriate external rotation and optimal tibial coverage without overhang. The femoral and tibial trial components are placed, and the surgeon tests 7 things: (1) overall varus-valgus alignment in full extension; (2) degree of extension (specifically noting any amount of recurvatum or flexion contracture); (3) flexion to gravity; (4) anteroposterior stability in flexion (using manual anterior-posterior translation of the tibia); (5) varus-valgus stability in extension, mid-flexion, and full flexion with use of a manual dynamic varus-valgus stress test; (6) patellar tracking; and (7) component rotation. At this point, if any of the above checkpoints are not within acceptable tolerances, additional ligamentous releases or cuts may be performed. After the surgeon is satisfied with the positioning and stability of the trial components, the tibial preparation is completed by seating the feet of the tibial bushing into the tray and drilling the tibia, then punching out the keel. The pins and the tray are removed, the retractors are taken out, and the knee is extended. The surgeon then performs a pulse lavage of the femur and tibia with normal saline solution. The final components are opened, attached to the inserters, and placed in plastic coverings. The final tibial baseplate is inserted and impacted, followed by the femoral component in a similar fashion. We ensure that no soft tissue is incarcerated under the components after impaction. A trial bearing is placed, and the knee is extended. The joint space is then bathed in approximately 500 mL of sterile 0.35% povidone-iodine solution, followed by pulsatile lavage with 1 L of sterile isotonic sodium chloride solution without antibiotics. Stability is then tested again, testing the (7) checkpoints previously discussed. At this point, the only modification that can be made is an increase or decrease in the polyethylene component. Our belief is that any additional changes that require removal or repositioning of the previously implanted cementless femoral and tibial components warrant modification to the cemented TKA. Once satisfied with the stability of the real implants and the trial tibial articular surface, the final polyethylene component is inserted. Finally, the tourniquet is released. The surgeon then irrigates the wound again and closes the arthrotomy and skin. Our preference is to utilize a knotless barbed suture for the arthrotomy closure, followed by 2-0 Vicryl (Ethicon) for subcutaneous closure and 2-0 monofilament knotless barbed suture for skin closure. Some surgeons may choose to utilize a non-barbed suture; however, the use of a barbed suture has been shown to be faster and equally as effective as a non-barbed suture in a large meta-analysis of patients undergoing TKA. Before final closure, the peri-incisional iodophor-impregnated antimicrobial incise drape is peeled back, and sterile 10% povidone-iodine is applied to the skin surrounding the incision. After subcuticular closure, adhesive skin glue is applied, followed by a waterproof dressing with the knee in flexion. ALTERNATIVES: There are numerous nonoperative treatments available for tibiofemoral osteoarthritis. According to the 2021 American Academy of Orthopaedic Surgeons Management of Osteoarthritis of the Knee (Non-Arthroplasty) Clinical Practice Guideline, these include bracing, nonsteroidal anti-inflammatory drugs, acetaminophen, supervised exercise, patient education, weight loss, and intra-articular corticosteroid injection, among others. When nonoperative treatment has failed, surgical treatment is then indicated for patients who continue to have symptoms that interfere with quality of life. Surgical treatments for tibiofemoral osteoarthritis primarily include unicompartmental knee arthroplasty or TKA, although proximal tibial osteotomy can be performed in some select cases according to disease severity and patient age. Each of these treatments is supported by the recent 2022 American Academy of Orthopaedic Surgeons Management of Osteoarthritis of the Knee (Non-Arthroplasty) Clinical Practice Guideline. RATIONALE: Historically, the initial generation of cementless TKA implant designs was associated with relatively high rates of failure and poor clinical outcomes when compared with cemented arthroplasty. However, there has been a renewed interest in cementless TKA with modern implant designs that incorporate newer biomaterials and porous coatings, with several recent studies demonstrating equivalence to cemented components at short-term, mid-term, and in some studies long-term follow-up. In a recent study, Kim et al. demonstrated 98% survival free from revision for aseptic loosening at 22 to 25 years postoperatively. In addition to at least equivalent long-term functional outcomes compared with cemented TKA, across multiple studies, several short-term benefits of cementless fixation have been reported, including decreased costs and the avoidance of complications associated with cement debris. Additionally, because there is no need to mix cement, there is a reduced burden of staff training and the elimination of possible variables that may affect cement integrity, in turn leading to improved operative efficiency and shorter operative time. Bone cement implantation syndrome (BCIS) has been reported in up to 28% of cases of cemented TKA, and has a substantial risk of morbidity and mortality. Cement debris can also remain in the knee if not retrieved after cement curing and prior to closure, which is believed to cause discomfort and polyethylene wear. This complication is also avoided when cementless implants are utilized. Additional factors leading to our preference for cementless TKA, when indicated, have not yet been proven in the literature but are intuitive concepts. For example, the lack of cement leads to easier removal of components during revision surgery, and preservation of bone stock is important for performing a successful revision TKA. EXPECTED OUTCOMES: Cementless TKA using modern implant designs has excellent long-term outcomes at up to 25 years. Kim et al. evaluated 261 patients who underwent bilateral simultaneous TKA with random assignment of cemented and cementless components in contralateral knees. In that study, the mean age was 63 years and the mean follow-up was 24 years. The authors found 98% survival without revision for aseptic loosening at 25 years. Similar findings have also been shown in older patients. For example, in a 2022 study by Goh et al., 7-year survivorship of modern implant designs was 100%. In that study of patients >75 years old, 120 cementless TKAs were matched in a 1:3 ratio with TKAs using cemented implants of the same modern design. Ultimately, no difference was seen in final postoperative scores or improvement in scores at 2 years. Seven-year survivorship free from aseptic revision was 99.4% for patients with cemented implants and 100% for patients with cementless implants. IMPORTANT TIPS: When deciding to perform cementless TKA, we consider a variety of preoperative factors, such as a history of osteoporosis, preoperative radiographs showing areas of bone loss, and a history of conditions associated with low bone mineral density.Intraoperative factors can also be considered when deciding between cementless and cemented implants. For example, tactile feedback when sawing can help to determine if bone is hard and sclerotic, which we believe indicates a better candidate for cementless implants.○ Note that during tibial preparation in a varus knee, you will typically have substantial sclerosis of the medial tibial plateau and relative osteopenia in the lateral tibial plateau because of longstanding differences in joint loading. This pattern is reversed in valgus knees.○ In general, we believe that the decision regarding bone integrity should be made primarily on the basis of the non-sclerotic side.With use of the techniques described in the present article, we do not have a preoperative alignment threshold or knee range-of-motion criteria for cementless TKA. More research is needed, however, on the long-term outcomes of cementless TKA when utilizing personalized alignment strategies, which may dictate the placement of components in substantial varus or valgus relative to the anatomic axis.When utilizing keeled tibial implants, we recommend drilling in reverse to pack the walls of the drill hole with bone rather than milling it out, which we believe increases support for bone growth.If there is almost no resistance while drilling in reverse, we believe this to be a poor prognostic sign for cementless TKA, and cementing should be considered.When sizing the tibial baseplate, the goal is to maximize the size of the tibia to fit on top of the rim of cortical bone without overhanging. Undersizing may increase the potential for implant subsidence.Osseous cuts with cementless components need to be perfect. Dome-shaped cuts are at risk for rocking and/or toggling, which could contribute to loosening over time.All 4 quadrants of the tibia should be checked to confirm a flat surface.Soft tissues can get incarcerated under the implant, which is of particular concern for cementless implants as this could impair osseous ingrowth.During trialing, ensure that the trial is completely flush on bone, which is an additional check to guard against toggling and/or loosening.When impacting the femoral component, we recommend applying an extension force so that the weight of the inserter does not pull the component into flexion; however, excessive extension force could also cause a fracture. ACRONYMS AND ABBREVIATIONS: IV = intravenousAP = anteroposterior.
104Cementless knee arthroplasty: a review of recent performance.PubMed
Ajay Asokan, Ricci Plastow, Babar Kayani, et al.
Bone Jt Open. 2021 Jan 22;2(1):48-57. doi: 10.1302/2633-1462.21.BJO-2020-0172.R1. eCollection 2021 Jan.
Cementless knee arthroplasty has seen a recent resurgence in popularity due to conceptual advantages, including improved osseointegration providing biological fixation, increased surgical efficiency, and reduced systemic complications associated with cement impaction and wear from cement debris. Increasingly younger and higher demand patients are requiring knee arthroplasty, and as such, there is optimism cementless fixation may improve implant survivorship and functional outcomes. Compared to cemented implants, the National Joint Registry (NJR) currently reports higher revision rates in cementless total knee arthroplasty (TKA), but lower in unicompartmental knee arthroplasty (UKA). However, recent studies are beginning to show excellent outcomes with cementless implants, particularly with UKA which has shown superior performance to cemented varieties. Cementless TKA has yet to show long-term benefit, and currently performs equivalently to cemented in short- to medium-term cohort studies. However, with novel concepts including 3D-printed coatings, robotic-assisted surgery, radiostereometric analysis, and kinematic or functional knee alignment principles, it is hoped they may help improve the outcomes of cementless TKA in the long-term. In addition, though cementless implant costs remain higher due to novel implant coatings, it is speculated cost-effectiveness can be achieved through greater surgical efficiency and potential reduction in revision costs. There is paucity of level one data on long-term outcomes between fixation methods and the cost-effectiveness of modern cementless knee arthroplasty. This review explores recent literature on cementless knee arthroplasty, with regards to clinical outcomes, implant survivorship, complications, and cost-effectiveness; providing a concise update to assist clinicians on implant choice. Cite this article: 2021;2(1):48-57.
105Cementless Total Knee Arthroplasty: A Comprehensive Review of the Literature.PubMed
Jared M Newman, Nipun Sodhi, Anton Khlopas, et al.
Orthopedics. 2018 Sep 1;41(5):263-273. doi: 10.3928/01477447-20180815-05. Epub 2018 Aug 21.
This review evaluated (1) original and newer cementless implants; (2) outcomes of newer designs; (3) risks and benefits; and (4) newer cementless vs cemented total knee arthroplasties. A search for all reports on cementless total knee arthroplasties published from January 2010 to April 2017 was performed, and 31 studies were included for final analysis. Newer cementless total knee arthroplasty designs have shown excellent survivorship, functional outcomes, and satisfaction rates in both young and elderly populations. Compared with cement fixation, there may be potential benefits with the newer cementless implants. However, these findings need to be further substantiated with additional studies reporting longer-term results. [Orthopedics. 2018; 41(5):263-273.].
106Uncemented Tibial Fixation Has Comparable Prognostic Outcomes and Safety Versus Cemented Fixation in Cruciate-Retaining Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials.PubMed
Kai Chen, Jintao Xu, Hanhao Dai, et al.
J Clin Med. 2023 Mar 1;12(5):1961. doi: 10.3390/jcm12051961.
BACKGROUND: Cemented and uncemented fixation are the primary methods of tibial prosthesis fixation in total knee arthroplasty. However, the optimal fixation method remains controversial. This article explored whether uncemented tibial fixation has better clinical and radiological outcomes, fewer complications, and revision rates compared to cemented tibial fixation. METHODS: We searched the PubMed, Embase, Cochrane Library, and Web of Science databases up to September 2022 to identify randomized controlled trials (RCTs) that compared uncemented total knee arthroplasty (TKA) and cemented TKA. The outcome assessment consisted of clinical and radiological outcomes, complications (aseptic loosening, infection, and thrombosis), and revision rate. Subgroup analysis was used to explore the effects of different fixation methods on knee scores in younger patients. RESULTS: Nine RCTs were finally analyzed with 686 uncemented knees and 678 cemented knees. The mean follow-up time was 12.6 years. The pooled data revealed significant advantages of uncemented fixations over cemented fixations in terms of the Knee Society Knee Score (KSKS) ( = 0.01) and the Knee Society Score-Pain (KSS-Pain) ( = 0.02). Cemented fixations showed significant advantages in maximum total point motion (MTPM) ( < 0.0001). There was no significant difference between uncemented fixation and cemented fixation regarding functional outcomes, range of motion, complications, and revision rates. When comparing among young people (<65 years), the differences in KSKS became statistically insignificant. No significant difference was shown in aseptic loosening and the revision rate among young patients. CONCLUSIONS: The current evidence shows better knee score, less pain, comparable complications and revision rates for uncemented tibial prosthesis fixation, compared to cemented, in cruciate-retaining total knee arthroplasty.
107Cemented vs. uncemented total knee arthroplasty in obese patients: A systematic review of implant survival, complications, and clinical outcomes.PubMed
Lorenzo Lo Carmine, Francesco Onorato, Carmelo Burgio, et al.
J Orthop. 2025 Mar 25;70:126-132. doi: 10.1016/j.jor.2025.03.049. eCollection 2025 Dec.
INTRODUCTION: Obesity is a primary global health concern that negatively affects the outcomes of total knee arthroplasty (TKA). To mitigate complications, both cemented and uncemented fixation techniques have been considered. However, there remains no consensus in the literature regarding the optimal fixation method for obese patients despite the renewed interest in uncemented fixation. This systematic review aims to compare the survival rates, causes of failure, and patient-reported outcome measures (PROMs) between cemented TKA (cTKA) and uncemented TKA (uTKA) in the obese population. MATERIALS AND METHODS: A comprehensive literature search was conducted according to PRISMA guidelines across five databases-PubMed, Scopus, Embase, Medline, and Cochrane-focusing on studies directly comparing cTKA and uTKA in obese patients. The ROBINS-I tool was used to assess the risk of bias, while the PRISMA flow diagram guided the study selection process based on predefined inclusion and exclusion criteria. This systematic review was registered on PROSPERO. RESULTS: Four retrospective studies encompassing 1622 patients met the inclusion criteria and were included in the final qualitative analysis. Among these, 50 % of patients underwent uTKA, with three studies exclusively analyzing individuals with at least class II obesity (BMI ≥35 kg/m). All four studies reported higher rates of aseptic loosening in the cemented fixation group. However, only two studies demonstrated a statistically significant improvement in implant survival, reduced aseptic loosening, and lower revision rates with cementless fixation in the short-to mid-term follow-up. Regarding clinical outcomes, only one study reported a significant improvement in Knee Society Score (KSS) function, range of motion (ROM), and pain scores in the cementless group compared to the cemented group, particularly in the subgroup analysis of posterior-stabilized constrained TKA. CONCLUSION: This systematic review suggests that in obese patients, particularly those with BMI ≥35 kg/m, cementless fixation offers comparable or superior implant survival rates and lower rates of aseptic loosening compared to cemented fixation in the short-to mid-term follow-up. Furthermore, cementless fixation may provide similar or enhanced clinical outcomes in this high-risk and growing patient population.
108Early experience with the ATTUNE Total Knee Replacement System.PubMed
Stefano Giaretta, Mattia Berti, Gian Mario Micheloni, et al.
Acta Biomed. 2019 Oct 29;90(12-S):98-103. doi: 10.23750/abm.v90i12-S.8997.
BACKGROUND: Modern TKA implants promise to improve functional outcomes, stability, patient satisfaction and operating room efficiency. The purpose of this retrospective study is to evaluate our short-term clinical and radiological results and survival using the ATTUNE Total Knee Replacement System. METHODS: The authors reviewed 228 primary cemented TKAs using ATTUNE Total Knee Replacement System which were implanted between 2014 and 2018 concerning short-term clinical and radiographical outcomes and survival. Clinical evaluation was performed using the Knee injury Osteoarthritis Outcome Score (KOOS), the Oxford Score and a Numeric Rating Scale (NRS) for pain. Radiographic analysis was performed using the Modern Knee Society Score Evaluation System. RESULTS: The means of the clinical results as measured with KOOS score were Pain 82,7, Symptoms 79, ADL 78,3, Sport and recreation 51,8 and QOL 78,6. The mean Oxford score was 35 and NRS 2. The mean ROM was 113,4 (SD 9,4 range 90-130). Radiographically mean mechanical axis was 1,97° of Varus and radiolucent lines were detected in 43 knees (22,4%). The survival rate is 98.4% at 2 years and 97.4% at 5 years. CONCLUSION: At short-term follow-up the ATTUNE Knee Replacement System provide excellent clinical and radiographical outcomes and good results regarding revision rate. Due to high incidence of radiolucent lines, those patients should be closely monitored even though they show no clinical evidence for loosening.
109Can the minimal clinically important difference (MCID) for the Oxford score, KOOS and its derivatives be identified in a French sample of total knee arthroplasties?PubMed
Tom Roussel, Julien Dartus, Gilles Pasquier, et al.
Orthop Traumatol Surg Res. 2025 May;111(3):103965. doi: 10.1016/j.otsr.2024.103965. Epub 2024 Jul 31.
CONTEXT: To assess the effect of a surgical procedure on a patient, it is conventional to use clinical scores before and after the procedure, but it is increasingly common and recommended to weight the results of these scores with the notion of minimal clinically important difference ("MCID"). This MCID should be determined using either the data distribution method based on score variation, or the anchor method, which uses an external question to categorize the results. MCIDs vary from one population to another, and to our knowledge there has been no investigation in France for total knee arthroplasties (TKAs). We therefore conducted a prospective study on a population of TKAs in order to: 1) Define MCID in France on a population of TKAs for the Oxford score, KOOS (Knee injury and Osteoarthritis Outcome Score) and its derivatives, 2) Determine whether MCID for these scores in France is comparable to results in the literature. HYPOTHESIS: Is the MCID for total knee arthroplasty in France comparable to other results in the literature? MATERIAL AND METHOD: This was a prospective observational study in which 218 patients (85 men, 133 women) with a mean age of 72 years [27-90] who had undergone a primary TKA out of 300 initially included responded, before and after surgery, to the Oxford-12, KOOS and Forgotten Joint Score (FJS) questions (mean follow-up 24 months). MCID was calculated using the distribution method as well as the anchor method ("improvement 1 to 5" and "improvement yes or no"). RESULTS: At a mean follow-up of 24 months [18-36], the Oxford-12 score increased from 16 ± 8 [0-41] to 34 ± 11 [6-48] (p < 0.001), all components of the KOOS score were improved and the FJS at follow-up was 47 ± 32 [0-100]. For the anchor "improvement 1 to 5", there were 14 unimproved patients, 23 patients in identical condition and 179 patients improved by surgery. For the anchor "are you improved yes/no", there were 8 unimproved patients, 22 in identical condition and 187 surgically-improved patients. The mean MCID for all methods (anchor method and distribution) was 10 [7-13] for Oxford-12, 12 [12-12] for KOOS Symptom, 14 [12-17] for KOOS Pain, 12 [11-14] for KOOS Function, 14 [12-16] for KOOS Sport, 15 [15-16] for KOOS Quality of Life (QOL), 11 [10-12] for KOOS 12, 15 [12-18] for KOOS 12 Pa in. 12 [12-13] for KOOS 12 Function, 15 [15-15] for KOOS 12 QOL, 14 [13-14] for KOOS Physical Function Short-form (PS) and 14 [13-16] for KOOS Joint Replacement (JR). DISCUSSION: The MCID for the Oxford-12, KOOS and its derivatives scores in a French population is comparable to that observed in other populations in the literature. LEVEL OF EVIDENCE: IV; prospective study without control group.
110Substantial clinical benefit and patient acceptable symptom states of the Forgotten Joint Score 12 after primary knee arthroplasty.PubMed
Siri Heijbel, Annette W-Dahl, Kjell G Nilsson, et al.
Acta Orthop. 2022 Jan 3;93:158-163. doi: 10.2340/17453674.2021.887.
Background and purpose - Knowing how to interpret values obtained with patient reported outcome measures (PROMs) is essential. We estimated the substantial clinical benefit (SCB) and patient acceptable symptom state (PASS) for Forgotten Joint Score 12 (FJS) and explored differences depending on methods used for the estimates. Patients and methods - The study was based on 195 knee arthroplasties (KA) performed at a university hospital. We used 1 item from the Knee injury and Osteoarthritis Outcome Score domain quality of life and satisfaction with surgery, obtained 1-year postoperatively, to assess SCB and PASS thresholds of the FJS with anchor-based methods. We used different combinations of anchor questions for SCB and PASS (satisfied, satisfied with no or mild knee difficulties, and satisfied with no knee difficulties). A novel predictive approach and receiver-operating characteristics curve were applied for the estimates. Results - 70 and 113 KAs were available for the SCB and PASS estimates, respectively. Depending on method, SCB of the FJS (range 0-100) was 28 (95% CI 21-35) and 22 (12-45) respectively. PASS was 31 (2-39) and 20 (10-29) for satisfied patients, 40 (31-47) and 38 (32-43) for satisfied patients with no/mild difficulties, and 76 (39-80) and 64 (55-74) for satisfied patients with no difficulties. The areas under the curve ranged from 0.82 to 0.88. Interpretation - Both the SCB and PASS thresholds varied depending on methodology. This may indicate a problem using meaningful values from other studies defining outcomes after KA. This study supports the premise of the FJS as a PROM with good discriminatory ability in patients undergoing KA.
111Patients Who Have Kellgren-Lawrence Grade 3 and 4 Osteoarthritis Benefit Equally From Total Knee Arthroplasty.PubMed
Graham S Goh, Andrew M Schwartz, Jennifer K Friend, et al.
J Arthroplasty. 2023 Sep;38(9):1714-1717. doi: 10.1016/j.arth.2023.03.068. Epub 2023 Apr 4.
BACKGROUND: Recently, some payers have limited access to total knee arthroplasty (TKA) to patients who have Kellgren-Lawrence (KL) grade 4 osteoarthritis only. This study compared the outcomes of patients who have KL grade 3 and 4 osteoarthritis after TKA to determine if this new policy is justified. METHODS: This was a secondary analysis of a series originally established to collect outcomes for a single, cemented implant design. A total of 152 patients underwent primary, unilateral TKA at two centers from 2014 to 2016. Only patients who had KL grade 3 (n = 69) or 4 (n = 83) osteoarthritis were included. There was no difference in age, sex, American Society of Anesthesiologists score, or preoperative Knee Society Score (KSS) between the groups. Patients who had KL grade 4 disease had a higher body mass index. KSS and Forgotten Joint Score (FJS) were collected preoperatively and at 6 weeks, 6 months, 1 year, and 2 years postoperatively. Generalized linear models were used to compare outcomes. RESULTS: Controlling for demographics, improvements in KSS were comparable between the groups at all time points. There was no difference in KSS, FJS, and the proportion that achieved the patient acceptable symptom state for FJS at 2 years. CONCLUSION: Patients who had KL grade 3 and 4 osteoarthritis experienced similar improvement at all time points up to 2 years after primary TKA. There is no justification for payers to deny access to surgical treatment for patients who have KL grade 3 osteoarthritis and have otherwise failed nonoperative treatment.
112Artificial intelligence and machine learning in knee arthroplasty.PubMed
Hugo C Rodriguez, Brandon D Rust, Martin W Roche, et al.
Knee. 2025 Jun;54:28-49. doi: 10.1016/j.knee.2025.02.014. Epub 2025 Feb 28.
BACKGROUND: Artificial intelligence (AI) and its subset, machine learning (ML), have significantly impacted clinical medicine, particularly in knee arthroplasty (KA). These technologies utilize algorithms for tasks such as predictive analytics and image recognition, improving preoperative planning, intraoperative navigation, and postoperative complication anticipation. This systematic review presents AI-driven tools' clinical implications in total and unicompartmental KA, focusing on enhancing patient outcomes and operational efficiency. METHODS: A systematic search was conducted across multiple databases including Cochrane Central Register of Controlled Trials, Embase, OVID Medline, PubMed, and Web of Science, following the PRISMA guidelines for studies published in the English language till March 2024. Inclusion criteria targeted adult human models without geographical restrictions, specifically related to total or unicompartmental KA. RESULTS: A total of 153 relevant studies were identified, covering various aspects of ML application for KA. Topics of studies included imaging modalities (n = 28), postoperative primary KA complications (n = 26), inpatient status (length of stay, readmissions, and cost) (n = 24), implant configuration (n = 14), revision (n = 12), patient-reported outcome measures (PROMs) (n = 11), function (n = 11), procedural communication (n = 8), total knee arthroplasty/unicompartmental knee arthroplasty prediction (n = 6), outpatient status (n = 4), perioperative efficiency (n = 4), patient satisfaction (n = 3), opioid usage (n = 3). A total of 66 ML models were described, with 48.7% of studies using multiple approaches. CONCLUSION: This review assesses ML applications in knee arthroplasty, highlighting their potential to improve patient outcomes. While current algorithms and AI show promise, our findings suggest areas for enhancement in predictive performance before widespread clinical adoption.
113Development of machine learning algorithms to predict achievement of minimal clinically important difference for the KOOS-PS following total knee arthroplasty.PubMed
Akhil Katakam, Aditya V Karhade, Austin Collins, et al.
J Orthop Res. 2022 Apr;40(4):808-815. doi: 10.1002/jor.25125. Epub 2021 Jul 18.
As cost-effective measures become increasingly implemented in the US healthcare system, changes in patient-reported outcome measure (PROM) scores can be utilized to indicate patient satisfaction following procedures including total knee arthroplasty (TKA). The primary aim of this study was to develop and evaluate machine learning algorithms to predict achievement of the minimal clinically important difference (MCID) for the Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS) at 1-year following TKA. A retrospective review of primary TKA patients between 2016 and 2018 was performed. Variables considered for prediction included demographics and preoperative PROMs. The KOOS-PS MCID was calculated via a distribution-based method. Five machine learning algorithms were developed and tested by discrimination, calibration, Brier score, and decision curve analysis. Among the 744 patients who met the inclusion criteria, 385 (72.8%) patients achieved the MCID. The elastic-net penalized logistic regression model was selected as the best performing model (c-statistic 0.77, calibration intercept -0.02, calibration slope 1.15, and Brier score 0.14). The most important variables for MCID achievement were preoperative KOOS-PS score, preoperative VAS Pain, preoperative opioid use, preoperative PROMIS global mental health score, age, and sex. Algorithms were incorporated into an open-access digital application available at https://sorg-apps.shinyapps.io/tka_koos_mcid/. This study is the first to predict the probability of achieving the KOOS-PS MCID following TKA using a machine learning-based approach. The results were used to develop a clinical decision aid based on commonly collected predictive variables to preoperatively predict an individual patient's likelihood of attaining an acceptable outcome following TKA.
114Comparison of an Artificial Intelligence-Enabled Patient Decision Aid vs Educational Material on Decision Quality, Shared Decision-Making, Patient Experience, and Functional Outcomes in Adults With Knee Osteoarthritis: A Randomized Clinical Trial.PubMed
Prakash Jayakumar, Meredith G Moore, Kenneth A Furlough, et al.
JAMA Netw Open. 2021 Feb 1;4(2):e2037107. doi: 10.1001/jamanetworkopen.2020.37107.
IMPORTANCE: Decision aids can help inform appropriate selection of total knee replacement (TKR) for advanced knee osteoarthritis (OA). However, few decision aids combine patient education, preference assessment, and artificial intelligence (AI) using patient-reported outcome measurement data to generate personalized estimations of outcomes to augment shared decision-making (SDM). OBJECTIVE: To assess the effect of an AI-enabled patient decision aid that includes education, preference assessment, and personalized outcome estimations (using patient-reported outcome measurements) on decision quality, patient experience, functional outcomes, and process-level outcomes among individuals with advanced knee OA considering TKR in comparison with education only. DESIGN, SETTING, AND PARTICIPANTS: This randomized clinical trial at a single US academic orthopedic practice included 129 new adult patients presenting for OA-related knee pain from March 2019 to January 2020. Data were analyzed from April to May 2020. INTERVENTION: Patients were randomized into a group that received a decision aid including patient education, preference assessment, and personalized outcome estimations (intervention group) or a group receiving educational material only (control group) alongside usual care. MAIN OUTCOMES AND MEASURES: The primary outcome was decision quality, measured using the Knee OA Decision Quality Instrument (K-DQI). Secondary outcomes were collaborative decision-making (assessed using the CollaboRATE survey), patient satisfaction with consultation (using a numerical rating scale), Knee Injury and Osteoarthritis Outcome Score Joint Replacement (KOOS JR) score, consultation time, TKR rate, and treatment concordance. RESULTS: A total of 69 patients in the intervention group (46 [67%] women) and 60 patients in the control group (37 [62%] women) were included in the analysis. The intervention group showed better decisional quality (K-DQI mean difference, 20.0%; SE, 3.02; 95% CI, 14.2%-26.1%; P < .001), collaborative decision-making (CollaboRATE, 8 of 69 [12%] vs 28 of 60 [47%] patients below median; P < .001), satisfaction (numerical rating scale, 9 of 65 [14%] vs 19 of 58 [33%] patients below median; P = .01), and improved functional outcomes at 4 to 6 months (mean [SE] KOOS JR, 4.9 [2.24] points higher in intervention group; 95% CI, 0.8-9.0 points; P = .02). The intervention did not significantly affect consultation time (mean [SE] difference, 2.23 [2.18] minutes; P = .31), TKR rates (16 of 69 [23%] vs 7 of 60 [12%] patients; P = .11), or treatment concordance (58 of 69 [84%] vs 44 of 60 [73%] patients; P = .19). CONCLUSIONS AND RELEVANCE: In this randomized clinical trial, an AI-enabled decision aid significantly improved decision quality, level of SDM, satisfaction, and physical limitations without significantly impacting consultation times, TKR rates, or treatment concordance in patients with knee OA considering TKR. Decision aids using a personalized, data-driven approach can enhance SDM in the management of knee OA. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03956004.
115Evaluating willingness for surgery using the SMART Choice (Knee) patient prognostic tool for total knee arthroplasty: study protocol for a pragmatic randomised controlled trial.PubMed
Yuxuan Zhou, Claire Weeden, Lauren Patten, et al.
BMC Musculoskelet Disord. 2022 Feb 24;23(1):179. doi: 10.1186/s12891-022-05123-0.
BACKGROUND: Approximately 1 in 5 patients feel unsatisfied after total knee arthroplasty (TKA). Prognostic tools may aid in the patient selection process and reduce the proportion of patients who experience unsatisfactory surgery. This study uses the prognostic tool SMART Choice (Patient Prognostic Tool for Total Knee Arthroplasty) to predict patient improvement after TKA. The tool aims to be used by the patient without clinician input and does not require clinical data such as X-ray findings or blood results. The objective of this study is to evaluate the SMART Choice tool on patient decision making, particularly willingness for surgery. We hypothesise that the use of the SMART Choice tool will influence willingness to undergo surgery, especially when used earlier in the patient TKA journey. METHODS: This is a multicentred, pragmatic, randomised controlled trial conducted in Melbourne, Australia. Participants will be recruited from the St. Vincent's Hospital, Melbourne (SVHM) Orthopaedic Clinic, and the client base of HCF, Australia (private health insurance company). Patients over 45 years of age who have been diagnosed with knee osteoarthritis and considering TKA are eligible for participation. Participants will be randomised to either use the SMART Choice tool or treatment as usual. The SMART Choice tool provides users with a prediction for improvement or deterioration / no change after surgery based on utility score change calculated from the Veterans-RAND 12 (VR-12) survey. The primary outcome of the study is patient willingness for TKA surgery. The secondary outcomes include evaluating the optimal timing for tool use and using decision quality questionnaires to understand the patient experience when using the tool. Participants will be followed up for 6 months from the time of recruitment. DISCUSSION: The SMART Choice tool has the potential to improve patient decision making for TKA. Although many prognostic tools have been developed for other areas of surgery, most are confined within academic bodies of work. This study will be one of the first to evaluate the impact of a prognostic tool on patient decision making using a prospective clinical trial, an important step in transitioning the tool for use in clinical practice. TRIAL REGISTRATION: Australia and New Zealand Clinical Trials Registry (ANZCTR) - ACTRN12622000072718 . Prospectively registered - 21 January 2022.
116Natural Language Processing of Patient-Experience Comments After Primary Total Knee Arthroplasty.PubMed
Patawut Bovonratwet, Tony S Shen, Wasif Islam, et al.
J Arthroplasty. 2021 Mar;36(3):927-934. doi: 10.1016/j.arth.2020.09.055. Epub 2020 Oct 8.
BACKGROUND: There is interest in improving patient experience after total knee arthroplasty (TKA) due to recent shifts toward value-based medicine. Patient narratives are a valuable but unexplored source of information. METHODS: Records of 319 patients who had undergone primary TKA between August 2016 and August 2019 were linked with vendor-supplied patient satisfaction data, which included patient comments and the Press Ganey satisfaction survey. Using machine-learning-based natural language processing, 1048 patient comments were analyzed for sentiment and classified into themes. Postoperative outcomes, patient-reported outcome measures, and traditional measures of satisfaction were compared between patients who provided a negative comment vs those who did not (positive, neutral, mixed grouped together). Multivariable regression was used to determine perioperative variables associated with providing a negative comment. RESULTS: Of the 1048 patient comments, 25% were negative, 58% were positive, 8% were mixed, and 9% were neutral. Top 2 themes of negative comments were room condition (25%) and inefficient communication (23%). There were no differences in most of the studied outcomes (eg, peak pain intensity, length of stay, or Knee Injury and Osteoarthritis Outcome Score Junior and pain scores at 6-week follow-up) between the 2 cohorts (P > .05). However, patients who made negative comments were less likely to highly recommend their hospital care to peers (P < .001). Finally, patients who had higher American Society of Anesthesiologists Score and those who received a scopolamine patch were more likely to provide negative comments (P < .05). CONCLUSION: Although the current study showed that patient satisfaction might not be a proxy for traditional objective perioperative outcomes, efforts to improve the nontechnical aspects of medicine are still crucial in providing patient-centered care.
117The relationship between design-based lateralization, humeral bearing design, polyethylene angle, and patient-related factors on surgical complications after reverse shoulder arthroplasty: a machine learning analysis.PubMed
Erick M Marigi, Jacob F Oeding, Micah Nieboer, et al.
J Shoulder Elbow Surg. 2025 Feb;34(2):462-472. doi: 10.1016/j.jse.2024.04.022. Epub 2024 Jun 8.
BACKGROUND: Technological advancements in implant design and surgical technique have focused on diminishing complications and optimizing performance of reverse shoulder arthroplasty (rTSA). Despite this, there remains a paucity of literature correlating prosthetic features and clinical outcomes. This investigation utilized a machine learning approach to evaluate the effect of select implant design features and patient-related factors on surgical complications after rTSA. METHODS: Over a 16-year period (2004-2020), all primary rTSA performed at a single institution for elective and traumatic indications with a minimum follow-up of 2 years were identified. Parameters related to implant design evaluated in this study included inlay vs. onlay humeral bearing design, glenoid lateralization (medialized or lateralized), humeral lateralization (medialized, minimally lateralized, or lateralized), global lateralization (medialized, minimally lateralized, lateralized, highly lateralized, or very highly lateralized), stem to metallic bearing neck shaft angle, and polyethylene neck shaft angle. Machine learning models predicting surgical complications were constructed for each patient and Shapley additive explanation values were calculated to quantify feature importance. RESULTS: A total of 3837 rTSA were identified, of which 472 (12.3%) experienced a surgical complication. Those experiencing a surgical complication were more likely to be current smokers (Odds ratio [OR] = 1.71; P = .003), have prior surgery (OR = 1.60; P < .001), have an underlying diagnosis of sequalae of instability (OR = 4.59; P < .001) or nonunion (OR = 3.09; P < .001), and required longer OR times (98 vs. 86 minutes; P < .001). Notable implant design features at an increased odds for complications included an inlay humeral component (OR = 1.67; P < .001), medialized glenoid (OR = 1.43; P = .001), medialized humerus (OR = 1.48; P = .004), a minimally lateralized global construct (OR = 1.51; P < .001), and glenohumeral constructs consisting of a medialized glenoid and minimally lateralized humerus (OR = 1.59; P < .001), and a lateralized glenoid and medialized humerus (OR = 2.68; P < .001). Based on patient- and implant-specific features, the machine learning model predicted complications after rTSA with an area under the receiver operating characteristic curve of 0.61. CONCLUSIONS: This study demonstrated that patient-specific risk factors had a more substantial effect than implant design configurations on the predictive ability of a machine learning model on surgical complications after rTSA. However, certain implant features appeared to be associated with a higher odd of surgical complications.
118Technology in Total Knee Arthroplasty in 2023.PubMed
Cale A Pagan, Theofilos Karasavvidis, Anna R Cohen-Rosenblum, et al.
J Arthroplasty. 2024 Sep;39(9S2):S54-S59. doi: 10.1016/j.arth.2024.07.028. Epub 2024 Jul 23.
Over the past few decades, instrumentation and techniques for total knee arthroplasty have evolved from conventional manual tools to a wide range of technologies, including calibrated guides for accurate bone cuts and alignment, smart tools, dynamic intraoperative sensors for soft tissue balancing, patient-specific guides, computer navigation, and robotics. This review is intended to provide an overview of the latest advancements in total knee arthroplasty technology, address potential challenges and solutions related to the application of these technologies, and explore their limitations.
119Ethical Considerations in Total Joint Arthroplasty.PubMed
Rupesh Tarwala, John J Mercuri, Richard Iorio, et al.
J Am Acad Orthop Surg. 2023 Oct 1;31(19):1001-1008. doi: 10.5435/JAAOS-D-22-00941. Epub 2023 Aug 8.
Hip and knee arthroplasty surgeries have excellent outcomes and notably improve quality of life. However, ethical issues permeate the practice of adult reconstruction, and as economics and technology evolve, these issues have become increasingly important. This article will review the currently published literature on ethical issues including industry influences, implants and instrumentations, surgical innovation, new technology adoptions, and healthcare policy-relevant issues, including patient cost sharing and bundled care programs. In addition, the direct marketing of implants from the manufacturer to the general public may falsely raise patient expectations concerning the long-term clinical outcome and performance of newer devices in the absence of long-term studies. This article will also focus on relevant contemporary ethical issues that do not necessarily have preexisting published literature or guidelines but, nonetheless, are crucial for adult reconstruction surgeons to address. These issues include access to care and challenges with orthopaedic resident and fellow education. Surgeons must understand the ethical issues that can arise in their clinical practice and how those issues affect patients. Clinicians are tasked with making the best-reasoned judgment possible to optimize their patients' outcomes. Still, the ability to standardize treatment while optimizing individual outcomes for unique patients remains a challenge.
120Enhanced Recovery After Surgery implementation in practice: an ethnographic study of services for hip and knee replacement.PubMed
Sarah Drew, Andrew Judge, Rachel Cohen, et al.
BMJ Open. 2019 Mar 5;9(3):e024431. doi: 10.1136/bmjopen-2018-024431.
OBJECTIVES: Enhanced Recovery After Surgery (ERAS) programmes aim to improve care quality by optimising components of the care pathway and programmes for hip and knee replacement exist across the UK. However, there is variation in delivery and outcomes. This study aims to understand processes that influence implementation using the Consolidated Framework for Implementation Research (CFIR) to inform the design and delivery of services. DESIGN: An ethnographic study using observations and interviews with staff involved in service delivery. Data were analysed using a thematic analysis, followed by an abductive approach whereby themes were mapped onto the 31 constructs and 5 domains of the CFIR. SETTING: Four hospital sites in the UK delivering ERAS services for hip and knee replacement. PARTICIPANTS: 38 staff participated including orthopaedic surgeons, nurses and physiotherapists. RESULTS: Results showed 17 CFIR constructs influenced implementation in all five domains. Within 'intervention characteristics', participants thought ERAS afforded advantages over alternative solutions and guidance was adaptable. In the 'outer setting', it was felt ERAS should be tailored to patients and education used to empower them in their recovery. However, there were concerns about postdischarge support and tensions with primary care. Within the 'inner setting', effective multidisciplinary collaboration was achieved by transferring knowledge about patients along the care pathway and multidisciplinary working practices. ERAS was viewed as a 'message' that had to be communicated consistently. There were concerns about resources and high volumes of patients. Staff access to information varied. At the domain 'characteristics of individuals', knowledge and beliefs impacted on implementation. Within 'process', involving opinion leaders in development and 'champions' who acted as a central point of contact, helped to engage staff. Formal and informal feedback helped to develop services. CONCLUSIONS: Findings demonstrate successful implementation involves empowering patients to work towards recovery, providing postdischarge support and promoting successful multidisciplinary team working.
121Implementation and effects of Enhanced Recovery After Surgery for hip and knee replacements and fractured neck of femur in New Zealand orthopaedic services.PubMed
Suzanne Proudfoot, Brandon Bennett, Simon Duff, et al.
N Z Med J. 2017 May 12;130(1455):77-90.
AIM: The National Orthopaedic Enhanced Recovery After Surgery (ERAS) Collaborative was launched in November 2013 to implement ERAS protocols for hip and knee total joint arthroplasty (TJA) and fractured neck of femur (NOF) in participating district health boards (DHBs) by December 2014. This paper reports on the results. METHOD: ERAS protocols were developed for hip and knee TJA and fractured NOF. Breakthrough Series collaborative methodology was used to implement the ERAS protocols in 18 DHBs. We collected monthly data on compliance with protocols and average length of stay (ALOS). Data were analysed using run charts and Shewhart control charts. RESULTS: The national percentage of ERAS components achieved across all DHBs rose from 33% to 75% on the elective knee TJA pathway, from 31% to 78% on the elective hip TJA pathway and from 29% to 51% on the acute fractured NOF pathway. The ALOS for knee TJA reduced from 5.4 days to 4.5 days. The ALOS for hip TJA reduced from 5.1 days to 4.3 days. There was no change in the ALOS for fractured NOF. CONCLUSION: The National Orthopaedic ERAS Collaborative increased uptake of ERAS protocols across all three pathways and decreased ALOS for the elective pathways among participating DHBs. There was no decrease in ALOS for the fractured NOF pathway. Collaborative improvement methodology can be used successfully to implement orthopaedic ERAS across New Zealand DHBs.
122Enhanced recovery after surgery in total joint arthroplasty: Nurses experiences of a pilot model of care.PubMed
Kate Schimmelbusch, Karen Blakemore, Marisa Delahunt, et al.
Int J Orthop Trauma Nurs. 2025 Aug;58:101212. doi: 10.1016/j.ijotn.2025.101212. Epub 2025 Jul 7.
BACKGROUND: Implementation of a fast-track model of care to support next-day discharge in joint arthroplasty can enhance the patient journey, improve nurses' job satisfaction while also reducing length of stay. OBJECTIVES: The objectives of this study were to explore nurses' experiences and perceptions of an Enhanced Recovery Program and develop an understanding of the contribution of the program to the delivery of care. The research question was: what are nurses' experiences and perceptions of an enhanced recovery program? METHODS: A multidisciplinary team developed, piloted, and evaluated an Enhanced Recovery Program for hip and knee arthroplasty patients. Nurses' experiences and perceptions of using an Enhanced Recovery Program were explored through semi-structured focus group discussion. Data were inductively thematically analysed through an iterative and reflexive process. FINDINGS: Eight nurses participated in the focus group in February 2025. Three themes became apparent: (1) Patient preparedness which encompassed patient education and goal setting expectations, (2) Nurses leading care including early mobilisation, multimodal analgesia, and use of a clinical pathway and (3) Nurse satisfaction resulting in perceived increased collaboration amongst the multidisciplinary team and positive workload impacts. CONCLUSIONS: There was a consensus amongst participants that the enhanced recovery program had a positive impact on participants' working lives and supported high quality and safe patient care.