II Orthopaedic Clinic, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano n. 1/10, 40136, Bologna, Italy.
II Orthopaedic Clinic, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano n. 1/10, 40136, Bologna, Italy.
Orthop Traumatol Surg Res. 2020 May;106(3):429-434. doi: 10.1016/j.otsr.2019.12.018. Epub 2020 Apr 3.
Bone defects during revision procedures for failed UKA represent a challenge even for the most experienced surgeons; therefore, an accurate preoperative planning remains essential to prevent dramatic scenarios in the surgical theatre.
Our hypothesis is that bearing thickness used in original UKA represents a reliable predictor of severe tibial bone loss, requiring a metallic augment or constrained implant, during revision to TKA.
Forty-two patients who underwent a total knee arthroplasty from failed UKA were identified from our institutional database and evaluated clinically using the Knee Society Score (KSS). A multivariate logistic regression analysis was performed using the presence of tibial augments or the need of varus-valgus constrained (VVC) prosthesis as depend variables, and patients' gender, age at revision procedure, side (medial or lateral), UKA tibial tray (all-polyethylene or metal back), bearing thickness (composite thicknesses of the metal-backed tray and insert or all-polyethylene tibial component ≤8mm or more than 8mm) and cause of failed UKA as independent variables.
A posterior-stabilized prosthesis was used in 27 cases (64.3%). An augment was necessary in 12 patients (28.6%). Initial bearing thickness greater than 8mm was associated with greater likelihood of a VVC implant (OR=11.78, 95% CI, 1.6583 to 83.6484, p=0.0137) and a tibial augment (OR=9.59, 95% CI, 1.327 to 69.395, p=0.0251). Tibial tray design, patients' gender or age during revision surgery, side or cause of failure were not associated to increased risk of augmentation or constrained implants.
Surgeons should be aware of the particular challenges that the conversion of a UKA to a TKA presents and be prepared to address them intraoperatively, with particular care to proper bone loss manage. Satisfying results can be achieved at mid-to-long term follow-up, if these procedures are planned accurately, and a precise analysis of failed UKA components, in particular bearing thickness, represents a helpful support in this context.
IV, retrospective case series.
即使对于经验最丰富的外科医生来说，UKA 翻修术中的骨缺损也是一个挑战；因此，准确的术前规划仍然是防止手术中出现戏剧性情况的关键。
我们的假设是，UKA 中使用的衬垫厚度是预测需要金属增强或约束型植入物以进行 TKA 翻修的严重胫骨骨丢失的可靠指标。
从我们的机构数据库中确定了 42 名因 UKA 失败而接受全膝关节置换术的患者，并使用膝关节协会评分 (KSS) 进行临床评估。使用存在胫骨增强或需要内翻-外翻约束 (VVC) 假体作为因变量，以及患者的性别、翻修手术时的年龄、侧别（内侧或外侧）、UKA 胫骨托（全聚乙烯或金属背侧）、衬垫厚度（金属背侧托和插入物或全聚乙烯胫骨组件的复合厚度≤8mm 或大于 8mm）和 UKA 失败的原因作为自变量，进行多变量逻辑回归分析。
27 例（64.3%）使用后稳定型假体。12 名患者（28.6%）需要增强。初始衬垫厚度大于 8mm 与 VVC 植入物（OR=11.78，95%CI，1.6583 至 83.6484，p=0.0137）和胫骨增强（OR=9.59，95%CI，1.327 至 69.395，p=0.0251）的发生更相关。胫骨托设计、患者在翻修手术时的性别或年龄、侧别或失败原因与增强或约束型植入物的风险增加无关。
外科医生应该意识到将 UKA 转换为 TKA 所带来的特殊挑战，并准备好在手术中解决这些问题，特别注意正确处理骨丢失。如果这些手术经过准确计划，并且对失败的 UKA 部件进行了精确分析，特别是衬垫厚度，则可以在中期至长期随访中获得满意的结果，这在这种情况下是一个有帮助的支持。
IV，回顾性病例系列。
