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

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