Segal Ava D, Shofer Jane B, Klute Glenn K
Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, Rehabilitation Research and Development, Department of Veterans Affairs Medical Center, Seattle, WA, USA.
Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, Rehabilitation Research and Development, Department of Veterans Affairs Medical Center, Seattle, WA, USA; Department of Mechanical Engineering, University of Washington, Seattle, WA, USA.
J Biomech. 2015 Nov 26;48(15):3982-3988. doi: 10.1016/j.jbiomech.2015.09.014. Epub 2015 Oct 9.
Maintaining balance while walking is challenging for lower limb amputees. The effect of prosthetic foot stiffness on recovery kinetics from an error in foot placement may inform prescription practice and lead to new interventions designed to improve balance. Ten unilateral transtibial amputees were fit with two prosthetic feet with different stiffness properties in random order. After a 3-week acclimation period, they returned to the lab for testing before switching feet. Twelve non-amputees also participated in a single data collection. While walking on an instrumented treadmill, we imposed a repeatable, unexpected medial or lateral disturbance in foot placement by releasing a burst of air at the ankle just before heel strike. Three-dimensional motion capture, ground reaction force and center of pressure (COP) data were collected for two steps prior, the disturbed step and three steps after the disturbance. During undisturbed walking, coronal ankle impulse was lower by 42% for amputees wearing a stiff compared to a compliant foot (p=0.017); however, across steps, both prosthetic recovery patterns were similar compared to the sound limb and non-amputees. Peak coronal hip moment was 15-20% lower for both foot types during undisturbed walking (p<0.001), with less change in response to the medial disturbance (p<0.001) compared to the sound limb and non-amputees. Amputee prosthetic COP excursion was unaffected by the disturbance (2.4% change) compared to the sound limb (59% change; p<0.001) and non-amputees (55% change; p<0.001). These findings imply that a prosthetic foot-ankle system able to contribute to ankle kinetics may improve walking balance among amputees.
对于下肢截肢者而言，行走时保持平衡颇具挑战。义肢足部刚度对因足部放置错误而产生的恢复动力学的影响，可能会为处方实践提供参考，并催生旨在改善平衡的新干预措施。十名单侧经胫骨截肢者被随机安装两种具有不同刚度特性的义肢足部。经过3周的适应期后，他们返回实验室进行测试，之后再更换足部。十二名非截肢者也参与了一次数据收集。在装有仪器的跑步机上行走时，我们在足跟即将触地前，通过在脚踝处释放一阵气流，对足部放置施加可重复的、意外的内侧或外侧干扰。在干扰前两步、受干扰步以及干扰后三步收集三维运动捕捉、地面反作用力和压力中心（COP）数据。在无干扰行走期间，与佩戴柔顺义肢足部的截肢者相比，佩戴坚硬义肢足部的截肢者的冠状面踝关节冲量低42%（p = 0.017）；然而，在各个步幅中，与健全肢体和非截肢者相比，两种义肢的恢复模式相似。在无干扰行走期间，两种义肢类型的冠状面髋关节峰值力矩均低15 - 20%（p < 0.001），与健全肢体和非截肢者相比，对内侧干扰的反应变化较小（p < 0.001）。与健全肢体（变化59%；p < 0.001）和非截肢者（变化55%；p < 0.001）相比，截肢者义肢的COP偏移不受干扰影响（变化2.4%）。这些发现表明，一个能够对踝关节动力学产生作用的义肢足部 - 踝关节系统，可能会改善截肢者的行走平衡。
