A novel biomechanical indicator for impaired ankle dorsiflexion function during walking in individuals with chronic stroke

Abstract

AbstractAnkle dorsiflexion function during swing phase of the gait cycle contributes to foot clearance and plays an important role in walking ability post-stroke. Commonly used biomechanical measures such as foot clearance and ankle joint excursion have limited ability to accurately evaluate dorsiflexor function in stroke gait. We retrospectively evaluated ankle angular velocity and ankle angular acceleration as direct measures for swing phase dorsiflexor function in post-stroke gait of 61 chronic stroke survivors. Our linear regression models revealed that peak ankle angular velocity (AAVP), peak ankle angular acceleration (AAAP), peak dorsiflexion angle (DFAP) and peak foot clearance (FCLP) during swing had a significant relationship (p < 0.05) with impaired dorsiflexion function. AAAPand DFAPaccounted for the most variance of dorsiflexion function. Additionally, AAVP, AAAP, FCLPduring swing, correlated significantly with all clinical outcome measures of walking ability. DFAPduring swing had a positive correlation only with FMA-LE. Post-hoc William’st-tests, used to compare the magnitude of difference between two non-independent correlations, revealed that the correlation between all clinical measures and DFAPwere significantly weaker than with AAVPand AAAP. We also found that correlation between FMA-LE and FCLPwas weaker than with AAVPand AAAP. We found an excellent test-retest reliability for both AAVP(ICC = 0.968) and AAAP(ICC = 0.947). These results suggest that DFAPmay only be associated with non-task specific isolated dorsiflexion movement, but not during walking. FCLPis associated with dorsiflexion function and walking ability measures but not as strongly as AAVPand AAAPpossibly because FCLPis influenced by contribution from hip and knee joint movements during walking. Therefore, we believe that AAVPand AAAPboth can be used as reliable measures of impaired dorsiflexion function in post-stroke gait.