Bioengineering Research Group, School of Engineering Sciences, Highfield Campus, University of Southampton, University Road, Southampton SO17 1BJ, UK.
Med Eng Phys. 2010 Jan;32(1):14-21. doi: 10.1016/j.medengphy.2009.10.002. Epub 2009 Nov 7.
Concerns over accelerated damage to the untreated compartment of the knee following unicompartmental knee arthroplasty (UKA), as well as the relatively poor success rates observed for lateral as opposed to the medial arthroplasty, remain issues for attention. Finite element analysis (FEA) was used to assess changes to the kinematics and potential for cartilage damage across the knee joint in response to the implantation of the Oxford Mobile Bearing UKA. FE models of lateral and medial compartment arthroplasty were developed, in addition to a healthy natural knee model, to gauge changes incurred through the arthroplasty. Varus-valgus misalignments were introduced to the femoral components to simulate surgical inaccuracy or over-correction. Boundary conditions from the Stanmore knee simulator during the stance phase of level gait were used. AP translations of the tibia in the medial UKA models were comparable to the behaviour of the natural knee models (+/-0.6mm deviation from pre-operative motion). Following lateral UKA, 4.1mm additional posterior translation of the tibia was recorded than predicted for the natural knee. IE rotations of the medial UKA models were less consistent with the pre-operative knee model than the lateral UKA models (7.7 degrees vs. 3.6 degrees deviation). Varus misalignment of the femoral prosthesis was more influential than valgus for medial UKA kinematics, whereas in lateral UKA, a valgus misalignment of the femoral prosthesis was most influential on the kinematics. Resection of the cartilage in the medial compartment reduced the overall risk of progressive OA in the knee, whereas removing the cartilage from the lateral compartment, and in particular introducing a valgus femoral misalignment, increased the overall risk of progressive OA in the knee. Based on these results, under the conditions tested herein, both medial and lateral UKA can be said to induce kinematics of the knee which could be considered broadly comparable to those of the natural knee, and that even a 10 degrees varus-valgus misalignment of the femoral component may not induce highly irregular kinematics. However, elevated posterior translation of the tibia in lateral UKA and large excursions of the insert may explain the higher incidence of bearing dislocation observed in some clinical studies.
人们仍然关注单髁膝关节置换术（UKA）后未治疗的膝关节区域加速损伤的问题，以及相对于内侧置换术，外侧置换术成功率相对较低的问题。有限元分析（FEA）用于评估牛津活动衬垫 UKA 植入后膝关节的运动学变化和软骨损伤的可能性。除了健康的自然膝关节模型外，还开发了外侧和内侧关节置换的 FE 模型，以衡量通过关节置换产生的变化。对股骨部件引入内翻-外翻对线不良，以模拟手术不准确或过度矫正。使用 Stanmore 膝关节模拟器在水平步态的站立阶段的边界条件。内侧 UKA 模型中胫骨的 AP 平移与自然膝关节模型的行为相似（与术前运动偏差+/-0.6mm）。在外侧 UKA 之后，胫骨的后向平移记录为 4.1mm，比自然膝关节预测的多。内侧 UKA 模型的 IE 旋转与术前膝关节模型不如外侧 UKA 模型一致（7.7 度与 3.6 度偏差）。股骨假体的内翻对线对线不良对内侧 UKA 运动学的影响大于外翻对线，而在外侧 UKA 中，股骨假体的外翻对线对线不良对运动学的影响最大。内侧关节间室软骨切除可降低膝关节进展性 OA 的总体风险，而切除外侧关节间室软骨，特别是引入外翻股骨对线不良，会增加膝关节进展性 OA 的总体风险。基于这些结果，在所测试的条件下，内侧和外侧 UKA 都可以被认为诱导膝关节的运动学，这些运动学可以被认为与自然膝关节的运动学大致相当，即使股骨部件的 10 度内翻-外翻对线不良也不会引起高度不规则的运动学。然而，外侧 UKA 中胫骨的后向平移升高和插入物的大偏移可能解释了一些临床研究中观察到的较高的轴承脱位发生率。
