Department of Mechanical Engineering, University of Texas at Austin, United States.
Department of Mechanical Engineering, University of Texas at Austin, United States.
J Biomech. 2019 Apr 18;87:150-156. doi: 10.1016/j.jbiomech.2019.02.026. Epub 2019 Mar 8.
It has long been held that hip abduction compensates for reduced swing-phase knee flexion angle, especially in those after stroke. However, there are other compensatory motions such as pelvic obliquity (hip hiking) that could also be used to facilitate foot clearance with greater energy efficiency. Our previous work suggested that hip abduction may not be a compensation for reduced knee flexion after stroke. Previous study applied robotic knee flexion assistance in people with post-stroke Stiff-Knee Gait (SKG) during pre-swing, finding increased abduction despite improved knee flexion and toe clearance. Thus, our hypothesis was that hip abduction is not a compensation for reduced knee flexion. We simulated the kinematics of post-stroke SKG on unimpaired individuals with three factors: a knee orthosis to reduce knee flexion, an ankle-foot orthosis commonly worn by those post-stroke, and matching gait speeds. We compared spatiotemporal measures and kinematics between experimental factors within healthy controls and with a previously recorded cohort of people with post-stroke SKG. We focused on frontal plane motions of hip and pelvis as possible compensatory mechanisms. We observed that regardless of gait speed, knee flexion restriction increased pelvic obliquity (2.8°, p < 0.01) compared to unrestricted walking (1.5°, p < 0.01), but similar to post-stroke SKG (3.4°). However, those with post-stroke SKG had greater hip abduction (8.2°) compared to unimpaired individuals with restricted knee flexion (4.2°, p < 0.05). These results show that pelvic obliquity, not hip abduction, compensates for reduced knee flexion angle. Thus, other factors, possibly neural, facilitate exaggerated hip abduction observed in post-stroke SKG.
长期以来，人们一直认为髋关节外展可以补偿摆动相膝关节屈曲角度减小，尤其是在中风后。然而，还有其他代偿运动，如骨盆倾斜（髋关节抬高），也可以用来更有效地清除脚部，同时节省能量。我们之前的工作表明，中风后髋关节外展可能不是膝关节屈曲减小的代偿。之前的研究在摆动前期对中风后僵硬膝步态（SKG）患者应用了机器人膝关节屈曲辅助，发现尽管膝关节屈曲和脚趾离地改善，但髋关节外展增加。因此，我们的假设是髋关节外展不是膝关节屈曲减小的代偿。我们用三个因素模拟了未受损个体的中风后 SKG 的运动学：一个用于减少膝关节屈曲的膝关节矫形器，一个中风后患者通常穿的踝足矫形器，以及匹配的步行速度。我们比较了健康对照组和之前记录的中风后 SKG 患者队列的实验因素之间的时空测量和运动学。我们关注髋关节和骨盆的额状面运动，因为它们可能是代偿机制。我们观察到，无论步行速度如何，与不受限制的行走相比，膝关节限制增加了骨盆倾斜度（2.8°，p < 0.01），与中风后 SKG 相似（3.4°）。然而，与膝关节受限的未受损个体相比，中风后 SKG 患者的髋关节外展更大（8.2°）（p < 0.05）。这些结果表明，骨盆倾斜度而不是髋关节外展补偿了膝关节屈曲角度的减小。因此，其他因素，可能是神经因素，促进了中风后 SKG 中观察到的髋关节外展的夸大。
