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

Ankle 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 (AAV ), peak ankle angular acceleration (AAA ), peak dorsiflexion angle (DFA ) and peak foot clearance (FCL ) during swing had a significant relationship (p < 0.05) with impaired dorsiflexion function. AAA and DFA accounted for the most variance of dorsiflexion function. Additionally, AAV , AAA , FCL during swing, correlated significantly with all clinical outcome measures of walking ability. DFA during swing had a positive correlation only with FMA-LE. Post-hoc William's -tests, used to compare the magnitude of difference between two non-independent correlations, revealed that the correlation between all clinical measures and DFA were significantly weaker than with AAV and AAA . We also found that correlation between FMA-LE and FCL was weaker than with AAV and AAA . We found an excellent test-retest reliability for both AAV (ICC = 0.968) and AAA (ICC = 0.947). These results suggest that DFA may only be associated with non-task specific isolated dorsiflexion movement, but not during walking. FCL is associated with dorsiflexion function and walking ability measures but not as strongly as AAV and AAA possibly because FCL is influenced by contribution from hip and knee joint movements during walking. Therefore, we believe that AAV and AAA both can be used as reliable measures of impaired dorsiflexion function in post-stroke gait.