Imperial College London, Structural Biomechanics, Dept. Civil and Environmental Engineering, Skempton Building, South Kensington Campus, SW7 2AZ London, UK.
J Biomech. 2011 Aug 11;44(12):2185-93. doi: 10.1016/j.jbiomech.2011.06.019. Epub 2011 Jul 13.
Musculoskeletal lower limb models have been shown to be able to predict hip contact forces (HCFs) that are comparable to in vivo measurements obtained from instrumented prostheses. However, the muscle recruitment predicted by these models does not necessarily compare well to measured electromyographic (EMG) signals. In order to verify if it is possible to accurately estimate HCFs from muscle force patterns consistent with EMG measurements, a lower limb model based on a published anatomical dataset (Klein Horsman et al., 2007. Clinical Biomechanics. 22, 239-247) has been implemented in the open source software OpenSim. A cycle-to-cycle hip joint validation was conducted against HCFs recorded during gait and stair climbing trials of four arthroplasty patients (Bergmann et al., 2001. Journal of Biomechanics. 34, 859-871). Hip joint muscle tensions were estimated by minimizing a polynomial function of the muscle forces. The resulting muscle activation patterns obtained by assessing multiple powers of the objective function were compared against EMG profiles from the literature. Calculated HCFs denoted a tendency to monotonically increase their magnitude when raising the power of the objective function; the best estimation obtained from muscle forces consistent with experimental EMG profiles was found when a quadratic objective function was minimized (average overestimation at experimental peak frame: 10.1% for walking, 7.8% for stair climbing). The lower limb model can produce appropriate balanced sets of muscle forces and joint contact forces that can be used in a range of applications requiring accurate quantification of both. The developed model is available at the website https://simtk.org/home/low_limb_london.
肌肉骨骼下肢模型已被证明能够预测髋关节接触力（HCFs），这些预测值与从仪器化假体获得的体内测量值相当。然而，这些模型预测的肌肉募集情况并不一定与测量的肌电图（EMG）信号很好地匹配。为了验证是否可以根据与 EMG 测量一致的肌肉力量模式准确估计 HCFs，基于已发表的解剖数据集（Klein Horsman 等人，2007.临床生物力学。22,239-247）的下肢模型已在开源软件 OpenSim 中实现。进行了一个周期对周期髋关节验证，以比较在四名关节置换患者的步态和爬楼梯试验中记录的 HCFs（Bergmann 等人，2001.生物力学杂志。34,859-871）。髋关节肌肉张力通过最小化肌肉力量的多项式函数来估计。通过评估目标函数的多个幂次获得的肌肉激活模式与文献中的 EMG 图谱进行了比较。计算出的 HCFs 表示当提高目标函数的幂次时，其大小呈单调增加的趋势；当最小化二次目标函数时，从与实验 EMG 图谱一致的肌肉力量中获得了最佳估计（在实验峰值帧上的平均高估：步行时为 10.1%，爬楼梯时为 7.8%）。下肢模型可以产生适当的平衡肌肉力量和关节接触力，可用于需要准确量化两者的各种应用。开发的模型可在网站 https://simtk.org/home/low_limb_london 上获得。
