步态周期下内侧半月板后根部分撕裂对膝关节生物力学的影响

Effect of partial posterior root tear of medial meniscus on biomechanics of the knee joint during gait cycle

背景:目前针对内侧半月板后根撕裂加速膝关节退变相关生物力学研究大多数仅限于在静态仿真设计的基础上对内侧半月板后根完全撕裂模型进行测试,而对内侧半月板后根部分撕裂在完整步态周期下的生物力学行为尚不清楚。目的:运用动态有限元分析的方法来比较正常膝关节模型与内侧半月板后根部分撕裂模型在完整步态周期下生物力学的差异。方法:以健康成年人右膝关节CT扫描数据为基础,建立包括骨、半月板、关节软骨在内的健康膝关节有限元模型,并在健康模型基础上进一步构建膝关节内侧半月板后根撕裂模型。分别在2种模型上施加ISO标准步态载荷进行仿真测试。比较2种模型对应部件在各时相下应力、位移和接触面积的差异。结果与结论:(1)在完整步态周期下,健康模型内侧半月板后根云图应力分布均匀,而病理模型则在损伤区出现应力集中表现,健康模型最大应力出现在30%时刻外侧半月板内缘,值为29.68 MPa,病理模型最大应力出现在50%时刻外侧半月板内缘,值为30.34 MPa;(2)在完整步态周期下,健康和病理模型胫骨软骨应力分布大体一致,2种模型承受最大应力分别出现在步态周围50%,20%时刻,值大小分别为5.11,6.85MPa;(3)2种模型的内侧间室组内差异大于外侧间室组内差异;病理模型各时相内侧胫骨平台应力均值比正常模型高9.3%,最大值为5.73 MPa,出现在支撑相中期;股骨、胫骨接触面积峰值均出现在40%时刻,病理模型各时相股骨软骨接触面积均值比正常模型减少14.6%;(4)研究结果表明在内侧半月板后根部分撕裂发生后膝关节生物力学特性的改变增加了骨关节炎的发病风险。

BACKGROUND:At present,most of biomechanical studies on medial meniscus posterior root tearing to accelerate knee joint degeneration are limited to testing the complete tear model of the posterior root of the medial meniscus on the basis of static simulation design.However,the biomechanical behavior of medial meniscus posterior root tear in the full gait cycle is not clear.OBJECTIVE:To compare the biomechanical differences between the normal knee joint model and the medial meniscus posterior root partial tear model in the complete gait cycle using dynamic finite element analysis method.METHODS:Based on the CT scan data of the right knee joint of healthy adults,the finite element model of healthy knee joint including bone,meniscus and articular cartilage was established,and the posterior root tear model of medial meniscus of knee joint was further established on the basis of healthy model.The standard gait load of ISO was applied to the two models for simulation test.The differences of stress,displacement and contact area of the corresponding parts of the two models were compared.RESULTS AND CONCLUSION:(1)Under the complete gait cycle,the stress distribution of the posterior root of the medial meniscus in the healthy model was uniform,while the pathological model showed stress concentration in the injured area.The maximum stress of the former appeared at the inner edge of the lateral meniscus at 30%time,with a value of 29.68 MPa.The latter maximum stress appeared at the inner edge of the lateral meniscus at 50%time,with a value of 30.34 MPa.(2)During the complete gait cycle,the stress distribution of tibial cartilage in healthy and pathological models was roughly the same.The maximum stress of the two models appeared at 50%and 20%around the gait,respectively,and the values were 5.11 MPa and 6.85 MPa,respectively.(3)The difference between the medial intercompartment group and the lateral intercompartment group was greater than that in the lateral intercompartment group.The average stress of the medial tibial plateau of the pathological model was 9.3%higher than that of the normal model,and the maximum value of 5.73 MPa appeared in the middle of the support phase.The peak contact area of femur and tibia appeared at 40%time,and the average contact area of femoral cartilage in each phase of the pathological model decreased by 14.6%compared with the normal model.(4)The results show that alterations in the biomechanical properties of the knee joint after a partial tear of the medial meniscus posterior root increase the risk of osteoarthritis.