School of Biomedical Engineering, Capital Medical University, Beijing, China.
Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing, China.
Orthop Surg. 2022 Aug;14(8):1836-1845. doi: 10.1111/os.13361. Epub 2022 Jun 29.
To assess the tibio-femoral contact forces before and after total knee arthroplasty (TKA) in patients with knee osteoarthritis (KOA) by three-dimensional (3D) finite element analysis (FEA) models and gait analysis.
Two hospitalized patients with Kellgren-Lawrence grade IV varus KOA and two healthy subjects were enrolled in this study. Both patients underwent unilateral TKA. FEA models were established based on CT and MR images of the knees of the patients with KOA and healthy subjects. Gait analysis was performed using a three-dimensional motion capture system with a force plate. Three direction forces at the ankle joints were calculated by inverse dynamic analysis, which provided the load for the FEA models. The total contact forces of the knee joints were also calculated by inverse dynamic analysis to enable comparisons with the results from the FEA models. The total knee contact forces, maximum von Mises stress, and stress distribution of the medial plateau were compared between the patients and healthy subjects. The distributions of the medial plateau force at 2 and 6 months postoperatively were compared with the distributions of the forces preoperatively and those in the healthy subjects.
During static standing, the medial plateau bore the most of the total contact forces in the knees with varus KOA (90.78% for patient 1 and 93.53% for patient 2) compared with 64.75 ± 3.34% of the total force in the healthy knees. At the first and second peaks of the ground reaction force during the stance phase of a gait cycle, the medial plateau bore a much higher percentage of contact forces in patients with KOA (74.78% and 86.48%, respectively, for patient 1; 70.68% and 83.56%, respectively, for patient 2) than healthy subjects (61.06% ± 3.43% at the first peak and 72.09% ± 1.83% at the second peak). Two months after TKA, the percentages of contact forces on the medial tibial plateau were 79.65%-85.19% at the first and second peaks of ground reaction forces during the stance phase of a gait cycle, and the percentages decreased to 53.99% - 68.13% 6 months after TKA.
FEA showed that TKA effectively restored the distribution of tibio-femoral contact forces during static standing and walking, especially 6 months after the surgery. The changes in the gait were consistent with the changes in the contact force distribution calculated by the FEA model.
通过三维有限元分析（FEA）模型和步态分析评估膝关节骨关节炎（KOA）患者全膝关节置换术（TKA）前后的胫股接触力。
本研究纳入了 2 名住院的膝关节 KOA 患者（Kellgren-Lawrence 分级 IV 级内翻）和 2 名健康受试者。这 2 名患者均接受了单侧 TKA。FEA 模型基于 KOA 患者和健康受试者膝关节的 CT 和 MRI 图像建立。使用三维运动捕捉系统和测力板进行步态分析。通过反向动力学分析计算踝关节的三个方向力，为 FEA 模型提供负载。通过反向动力学分析还计算了膝关节的总接触力，以便与 FEA 模型的结果进行比较。比较了患者与健康受试者的膝关节总接触力、最大 von Mises 应力和内侧平台的应力分布。比较了术后 2 个月和 6 个月时内侧平台力的分布与术前分布和健康受试者的分布。
在静态站立时，内翻型 KOA 膝关节的内侧平台承受了大部分的总接触力（患者 1 为 90.78%，患者 2 为 93.53%），而健康膝关节的总力中只有 64.75±3.34%作用于内侧平台。在步态周期支撑相的第一和第二地面反力峰值时，KOA 患者的内侧平台承受了更高比例的接触力（患者 1 分别为 74.78%和 86.48%，患者 2 分别为 70.68%和 83.56%），而健康受试者分别为 61.06±3.43%（第一峰值）和 72.09±1.83%（第二峰值）。TKA 术后 2 个月，在步态周期支撑相的第一和第二地面反力峰值时，内侧胫骨平台的接触力百分比分别为 79.65%-85.19%，而术后 6 个月时则下降至 53.99%-68.13%。
FEA 显示 TKA 有效地恢复了静态站立和行走时的胫股接触力分布，尤其是术后 6 个月。步态的变化与 FEA 模型计算的接触力分布变化一致。
