Department of Biomechanics, University of Nebraska at Omaha, Omaha, NE, United States of America.
Department of Clinical and Scientific Affairs, Hanger Clinic, Houston, TX, United States of America.
PLoS One. 2018 Oct 3;13(10):e0205098. doi: 10.1371/journal.pone.0205098. eCollection 2018.
Stride-to-stride fluctuations of joint kinematics during walking reflect a highly structured organization that is characteristic of healthy gait. The organization of stride-to-stride fluctuations is disturbed in lower-limb prosthesis users, yet the factors contributing to this difference are unclear. One potential contributor to the changes in stride-to-stride fluctuations is the altered push-off mechanics experienced by passive prosthesis users. The purpose of our study was to determine if changes in push-off mechanics affect stride-to-stride fluctuations in transtibial amputees. Twenty-two unilateral transtibial amputees were enrolled in the 6-week cross-over study, where High and Low Activity (based on the Medicare Functional Classification System) prostheses were worn for three weeks each. Data collection took place at the end of the third week. Participants walked on a treadmill in a motion capture laboratory to quantify stride-to-stride fluctuations of the lower extremity joint angle trajectories using the largest Lyapunov Exponent, and over floor-embedded force platforms to enable calculating push-off work from the prosthesis and the sound limb. Push-off work was 140% greater in the High Activity prosthesis compared to the Low Activity prosthesis (p < 0.001), however no significant change was observed in stride-to-stride fluctuations of the ankle between the two prosthesis types (p = 0.576). There was no significant correlation between changes in prosthesis push-off work and the largest Lyapunov exponent. Though differences in push-off work were observed between the two prosthesis types, stride-to-stride fluctuations remained similar, indicating that prosthesis propulsion mechanics may not be a strong determinant of stride-to-stride fluctuations in unpowered transtibial prosthesis users.
在行走过程中，关节运动的步间波动反映了一种高度结构化的组织，这种组织是健康步态的特征。下肢假肢使用者的步间波动组织受到干扰，但导致这种差异的因素尚不清楚。步间波动变化的一个潜在因素是被动假肢使用者经历的改变的蹬离力学。我们研究的目的是确定蹬离力学的变化是否会影响胫骨截肢者的步间波动。22 名单侧胫骨截肢者参加了为期 6 周的交叉研究，其中高活动（基于医疗保险功能分类系统）和低活动（Low Activity）假肢各佩戴 3 周。数据采集在第三周结束时进行。参与者在运动捕捉实验室的跑步机上行走，使用最大 Lyapunov 指数量化下肢关节角度轨迹的步间波动，并在地板嵌入式力平台上测量假肢和健肢的蹬离功。与低活动假肢相比，高活动假肢的蹬离功增加了 140%（p < 0.001），但两种假肢类型之间踝关节的步间波动没有明显变化（p = 0.576）。假肢蹬离功的变化与最大 Lyapunov 指数之间没有显著相关性。尽管两种假肢类型之间观察到蹬离功的差异，但步间波动仍然相似，这表明假肢推进力学可能不是无动力胫骨假肢使用者步间波动的主要决定因素。
