Department of Orthopedic Surgery, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea.
Department of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Republic of Korea.
J Orthop Surg Res. 2020 Nov 10;15(1):517. doi: 10.1186/s13018-020-02047-0.
Unicompartmental knee arthroplasty (UKA) is an effective treatment for end-stage, symptomatic unicompartmental osteoarthritis of the knee joint. However, patellofemoral joint degeneration is a contraindication to medial UKA. Therefore, the objective of this study was to evaluate the biomechanical effect of medial UKA using fixed-bearing (FB) and mobile-bearing (MB) design prostheses on the patellofemoral joint.
A three-dimensional finite-element model of a normal knee joint was developed using medical image data. We performed statistical analysis for each model. The differences in contact stress on the patellofemoral joint and the quadriceps force between the FB and MB designs were evaluated under a deep-knee-bend condition.
At an early flexion angle, the results of contact stress showed no significant difference between the FB and MB medial UKA models compared with the intact model. However, at high flexion angles, we observed a significant increase in contact stress with the FB models compared with the intact model. On the contrary, in the case of the MB models, we found no statistically significant increment compared with the intact model. A larger quadriceps force was needed to produce an identical flexion angle for both the FB and MB UKA designs than for the intact model. At high flexion angles, a significant increase quadriceps force whit the FB model compared with the intact model.
Our results indicate that with medial UKA, the contact stress increased and greater quadriceps force was applied to the patellofemoral joint. However, performing UKA on a patellofemoral joint with osteoarthritis should not be difficult, unless anterior knee pain is present, because the increase in contact stress is negligible.
单髁膝关节置换术（UKA）是治疗膝关节单间室晚期、症状性骨关节炎的有效方法。然而，髌股关节退变是内侧 UKA 的禁忌症。因此，本研究旨在评估固定（FB）和活动（MB）衬垫设计假体行内侧 UKA 对髌股关节的生物力学影响。
利用医学影像数据建立了一个正常膝关节的三维有限元模型。我们对每个模型进行了统计分析。在深屈膝条件下，评估了 FB 和 MB 设计在髌股关节接触压力和股四头肌力方面的差异。
在早期屈曲角度时，FB 和 MB 内侧 UKA 模型与完整模型相比，接触压力结果无显著差异。然而，在高屈曲角度时，我们观察到 FB 模型的接触压力显著增加，与完整模型相比。相反，对于 MB 模型，与完整模型相比，我们没有发现统计学上的显著增加。对于 FB 和 MB UKA 设计，需要更大的股四头肌力来产生相同的屈曲角度，而对于完整模型则不需要。在高屈曲角度时，FB 模型的股四头肌力显著增加，与完整模型相比。
我们的研究结果表明，行内侧 UKA 时，髌股关节接触压力增加，股四头肌力增加。然而，除非存在前膝疼痛，否则对髌股关节行 UKA 并不困难，因为接触压力的增加是微不足道的。
