An Investigation of Mediolateral Foot Placement during Post-Stroke Gait.

摘要

During locomotion, mediolateral (ML) foot placement is important for redirecting body center of mass trajectory and maintaining dynamic balance. Following a stroke, neuromuscular deficits may impair ML foot placement ability, with negative implications for balance during gait. Specifically, the swing phase of the affected limb is often characterized by an equinovarus posturing of the foot and ankle complex and reduced knee flexion. These deficits increase effective leg length (LL) such that mid-swing toe clearance is inadequate on the affected side. Adaptive swing phase movements, including hip hiking and circumduction, are often used to create toe clearance. However, these compensatory movements may be associated with reduced ML foot placement accuracy. Furthermore, equinovarus correction with an ankle-foot orthosis (AFO) may reduce the use of compensatory swing phase movements and improve ML foot placement ability.;To assess these ideas, subjects were instructed to walk at four step widths measured as a percent of leg length (LL): 0%, 15%, 30%, and 45% while motion data were collected. We tested 13 chronic post-stroke individuals with and without an AFO and 6 able-bodied controls. The findings from these studies indicate that ML foot placement ability is impaired bilaterally in post-stroke individuals compared to controls. A smaller range of step widths is achievable during level ground walking post-stroke. Furthermore, equinovarus correction did not significantly reduce compensatory swing phase movements or improve ML foot placement ability at any step width condition. The narrowest step width condition revealed unique insight. Notably, in the No AFO 0% LL condition preferred walking speed, hip ab/adduction range of motion, and sound limb hip abduction strength were identified as variables strongly associated with affected limb ML foot placement accuracy. Future work should continue to explore the bilateral and complex role of the hip during post-stroke locomotion.