Strategies to adapt walking mechanics to path curvature after a stroke

Objective: The ability to turn while walking is compromised in people with stroke. The aim of this study was to understand the contribution of biomechanical gait impairments to locomotor adapta- tions to path curvature in people with stroke. Data were collected from eight individuals with hemiparesis due to a stroke and 12 age-matched able-bodied individuals. Participants walked along four paths of different curvature (straight line, large circle, medium circle, small circle) while whole body kinematic data in three dimensions were collected. A modulation index representing the slope of the regression line between peak joint angle and path curvature at specific phases of the step cycle was computed to represent joint kinematic modulation patterns.

Results: In able-bodied individuals, we observed consistent modula- tion of transverse and frontal plane movements at the ankle and hip as path curvature increased. For example, in order to walk smoothly around the circle, the control group increased the amplitude of hip adduction in the leg located on the inside of the circle during stance. In individuals with stroke, we observed disordered modulation of the adaptation of frontal and transverse kinematic movement parameters as path curvature increased. In general, the stroke group would show reduced hip adduction on their affected leg even if it was on the inside of the turn. Conclusions: Adaptations in the kinematic pattern seen during curved walking in able-bodied participants were not seen in the stroke group.