Miller Ross H, Esterson Aryeh Y, Shim Jae Kun
Department of Kinesiology, University of Maryland, College Park, MD, USA; Neuroscience & Cognitive Science Program, University of Maryland, College Park, MD, USA.
Department of Kinesiology, University of Maryland, College Park, MD, USA.
Knee. 2015 Dec;22(6):481-9. doi: 10.1016/j.knee.2015.06.014. Epub 2015 Jul 26.
Gait modification is often used to reduce the external knee adduction moment (KAM) in human walking, but the relationship between KAM reduction and changes in medial knee joint contact force (JCF) is not well established. Our purpose was to examine the limiting case of KAM-based gait modification: reducing the KAM as much as possible, and the resulting effects on JCF.
We used musculoskeletal modeling to perform three optimal control simulations: normal walking, a modified gait that reduced the KAM as much as theoretically possible (Min(KAM) simulation), and a second modified gait that minimized the KAM plus the metabolic cost of transport (Min(KAM+CoT) simulation).
The two modified gaits both reduced the peak KAM from normal walking (-82% for Min(KAM) simulation, -74% for Min(KAM+CoT) simulation) by increasing trunk lean, toe-out, and step width, and reducing knee flexion. Even though the Min(KAM+CoT) simulation had the larger KAM, it had a greater reduction in peak medial JCF (-27%) than the Min(KAM) simulation (-15%) because it reduced the KAM using less knee muscle activity. These results were qualitatively robust to a sensitivity analysis of the knee joint model, but the magnitude of changes varied by an order of magnitude.
The results suggest that (i) gait modification can benefit from considering whole-body motion rather than single adjustments, (ii) accurate interpretation of KAM effects on medial JCF requires consideration of muscle forces, and (iii) subject-specific knee models are needed to accurately determine the magnitude of KAM reduction effects on JCF.
步态调整常用于减少人体行走时的膝关节内收力矩（KAM），但KAM降低与膝关节内侧接触力（JCF）变化之间的关系尚未明确确立。我们的目的是研究基于KAM的步态调整的极限情况：尽可能降低KAM，并观察其对JCF的影响。
我们使用肌肉骨骼模型进行了三个最优控制模拟：正常行走、一种理论上尽可能降低KAM的改良步态（最小化KAM模拟）以及另一种最小化KAM加上运输代谢成本的改良步态（最小化KAM+CoT模拟）。
两种改良步态均通过增加躯干前倾、外八字和步幅宽度以及减少膝关节屈曲，降低了正常行走时的峰值KAM（最小化KAM模拟降低了82%，最小化KAM+CoT模拟降低了74%）。尽管最小化KAM+CoT模拟的KAM较大，但由于其使用较少的膝关节肌肉活动来降低KAM，其峰值内侧JCF的降低幅度（27%）比最小化KAM模拟（15%）更大。这些结果在对膝关节模型的敏感性分析中具有定性稳健性，但变化幅度相差一个数量级。
结果表明，（i）步态调整可受益于考虑全身运动而非单一调整；（ii）准确解释KAM对内侧JCF的影响需要考虑肌肉力量；（iii）需要个体特异性膝关节模型来准确确定KAM降低对JCF的影响幅度。
