Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill & North Carolina State University, Raleigh, NC, USA.
Gait Posture. 2013 Sep;38(4):818-23. doi: 10.1016/j.gaitpost.2013.04.002. Epub 2013 Apr 28.
Over the last half-century, the field of prosthetic engineering has continuously evolved with much attention being dedicated to restoring the mechanical energy properties of ankle joint musculatures during gait. However, the contributions of 'distal foot structures' (e.g., foot muscles, plantar soft tissue) have been overlooked. Therefore, the purpose of this study was to quantify the total mechanical energy profiles (e.g., power, work, and work-ratio) of the natural ankle-foot system (NAFS) by combining the contributions of the ankle joint and all distal foot structures during stance in level-ground steady state walking across various speeds (0.4, 0.6, 0.8 and 1.0 statures/s). The results from eleven healthy subjects walking barefoot indicated ankle joint and distal foot structures generally performed opposing roles: the ankle joint performed net positive work that systematically increased its energy generation with faster walking speeds, while the distal foot performed net negative work that systematically increased its energy absorption with faster walking speeds. Accounting for these simultaneous effects, the combined ankle-foot system exhibited increased work-ratios with faster walking. Most notably, the work-ratio was not significantly greater than 1.0 during the normal walking speed of 0.8 statures/s. Therefore, a prosthetic design that strategically exploits passive-dynamic properties (e.g., elastic energy storage and return) has the potential to replicate the mechanical energy profiles of the NAFS during level-ground steady-state walking.
在过去的半个世纪中，假肢工程领域不断发展，非常注重在步态过程中恢复踝关节肌肉的机械能量特性。然而，“远端足部结构”（例如足部肌肉、足底软组织）的贡献却被忽视了。因此，本研究的目的是通过结合踝关节和所有远端足部结构在水平地面稳态行走中的贡献，来量化自然踝足系统（NAFS）的总机械能量谱（例如功率、功和功比），行走速度分别为 0.4、0.6、0.8 和 1.0 步/秒。11 名健康受试者赤脚行走的结果表明，踝关节和远端足部结构通常起着相反的作用：踝关节进行净正功，随着行走速度的加快，其能量生成系统地增加，而远端足部结构进行净负功，随着行走速度的加快，其能量吸收系统地增加。考虑到这些同时发生的影响，联合踝足系统在行走速度加快时表现出增加的功比。值得注意的是，在 0.8 步/秒的正常行走速度下，功比并没有显著大于 1.0。因此，具有战略利用被动动力学特性（例如弹性储能和回弹）的假肢设计有可能在水平地面稳态行走中复制 NAFS 的机械能量谱。
