The interaction between the prescribed prosthetic knee and foot is critical to the safety of transfemoral prosthesis users primarily during the stance phase of the gait, when knee buckling can result in a fall. Nonetheless, there is still a need for standardized approaches to quantify the effects of prosthetic component interactions and associated mechanical function on user gait biomechanics. A numerical model was defined to simulate sagittal plane prosthetic limb stance based on a single inverted pendulum and predict effects of prosthetic knee alignment and foot stiffness on knee moment to identify optimal solutions. Model validation against laboratory gait data suggests it is appropriate to preliminary simulate prosthetic gait during single-limb support, when prosthetic knee stability may be most at risk given reliance on the prosthetic limb and proximal anatomy, but only for knees with flexion smaller than 4°. Model predictions identify a solution space containing those combinations of knee alignment and foot stiffness (via roll-over shape radius) guaranteeing knee stability in early and mid- single-limb support, whilst facilitating knee break at the end of it. Specifically, a posterior to in-line knee alignment should be combined with low to medium ankle-foot stiffness, whereas anterior knee alignments and rigid feet should likely be avoided. Clinicians can use these solution spaces to optimize transfemoral prostheses including knees with little to no change in stance flexion, ensuring the safety of users. Model prediction can further inform in-vivo investigations on commercial device interactions, providing evidence for future Clinical Practice Guidelines on transfemoral prostheses design.

中文翻译：

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使用简单的步行模型优化经股假肢的假肢稳定性——初步研究


规定的假肢膝关节和足部之间的相互作用对于经股假肢使用者的安全至关重要，主要是在步态的站立阶段，此时膝关节屈曲可能导致跌倒。尽管如此，仍然需要标准化方法来量化假肢部件相互作用和相关机械功能对用户步态生物力学的影响。定义了一个数值模型来模拟基于单个倒立摆的矢状面假肢姿势，并预测假肢膝关节对齐和足部刚度对膝力矩的影响，以确定最佳解决方案。针对实验室步态数据的模型验证表明，在单肢支撑期间初步模拟假肢步态是适当的，因为考虑到对假肢和近端解剖结构的依赖，假肢膝关节稳定性可能面临最大风险，但仅适用于屈曲小于 4° 的膝关节。模型预测确定了一个解决方案空间，其中包含膝盖对齐和足部刚度（通过翻转形状半径）的组合，保证早期和中期单肢支撑中的膝盖稳定性，同时促进其末端的膝盖断裂。具体来说，后向直线膝盖对齐应与低至中度踝足刚度相结合，而前膝对齐和僵硬的足部则应避免。临床医生可以使用这些解决方案空间来优化经股假体（包括膝盖），而姿势弯曲几乎没有变化，从而确保用户的安全。模型预测可以进一步为商业设备相互作用的体内研究提供信息，为未来经股动脉假体设计的临床实践指南提供证据。