Division of Applied Mechanics, Department of Mechanical Engineering, École Polytechnique, P.O. Box 6079, Station "centre-ville", Montréal, Québec, Canada H3C 3A7.
Division of Applied Mechanics, Department of Mechanical Engineering, École Polytechnique, P.O. Box 6079, Station "centre-ville", Montréal, Québec, Canada H3C 3A7.
J Biomech. 2014 May 7;47(7):1696-703. doi: 10.1016/j.jbiomech.2014.02.028. Epub 2014 Mar 3.
Medial knee osteoarthritis is a debilitating disease. Surgical and conservative interventions are performed to manage its progression via reduction of load on the medial compartment or equivalently its surrogate measure, the external adduction moment. However, some studies have questioned a correlation between the medial load and adduction moment. Using a musculoskeletal model of the lower extremity driven by kinematics-kinetics of asymptomatic subjects at gait midstance, we aim here to quantify the relative effects of changes in the knee adduction angle versus changes in the adduction moment on the joint response and medial/lateral load partitioning. The reference adduction rotation of 1.6° is altered by ±1.5° to 3.1° and 0.1° or the knee reference adduction moment of 17Nm is varied by ±50% to 25.5Nm and 8.5Nm. Quadriceps, hamstrings and tibiofemoral contact forces substantially increased as adduction angle dropped and diminished as it increased. The medial/lateral ratio of contact forces slightly altered by changes in the adduction moment but a larger adduction rotation hugely increased this ratio from 8.8 to a 90 while in contrast a smaller adduction rotation yielded a more uniform distribution. If the aim in an intervention is to diminish the medial contact force and medial/lateral load ratio, a drop of 1.5° in adduction angle is much more effective (causing respectively 12% and 80% decreases) than a reduction of 50% in the adduction moment (causing respectively 4% and 13% decreases). Substantial role of changes in adduction angle is due to the associated alterations in joint nonlinear passive resistance. These findings explain the poor correlation between knee adduction moment and tibiofemoral compartment loading during gait suggesting that the internal load partitioning is dictated by the joint adduction angle.
内侧膝关节骨关节炎是一种使人虚弱的疾病。通过减少内侧间室的负荷或等效的替代测量值，即外部内收力矩，来进行手术和保守干预以控制其进展。然而，一些研究对内侧负荷和内收力矩之间的相关性提出了质疑。本研究使用下肢运动动力学-动力学的无症候群受试者的运动中期的运动学模型，旨在量化膝关节内收角变化与内收力矩变化对关节反应和内侧/外侧负荷分配的相对影响。参考内收旋转 1.6°通过±1.5°到 3.1°和 0.1°或膝关节参考内收力矩 17Nm 通过±50%到 25.5Nm 和 8.5Nm 进行改变。当内收角降低时，股四头肌、腘绳肌和胫骨股骨接触力显著增加，当内收角增加时，接触力减少。内收力矩变化对内收力矩的影响很小，但较大的内收旋转大大增加了内收力矩的比值，从 8.8 增加到 90，而较小的内收旋转则产生了更均匀的分布。如果干预的目的是减少内侧接触力和内侧/外侧负荷比，内收角下降 1.5°比内收力矩减少 50%更有效（分别导致 12%和 80%的减少）。内收角变化的主要作用是由于关节非线性被动阻力的相关变化。这些发现解释了在步态中膝关节内收力矩和胫骨股骨间室负荷之间的相关性较差，表明内部负荷分配由关节内收角决定。
