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

Background: Ankle dorsiflexion function during swing phase 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 impaired dorsiflexor function.
Research Question: Can ankle angular velocity and acceleration be used as reliable measurers of dorsiflexion function in post-stroke gait?
Methods: Using linear regression and Pearson's correlation we retrospectively compared peak ankle angular velocity (Aω _P ), peak ankle angular acceleration (Aα _P ), peak dorsiflexion angle (DFA _P ) and peak foot clearance (FCL _P ) as direct measures for swing phase dorsiflexor function in 60 chronic stroke survivors. Intraclass correlation coefficient (ICC) analysis was used for test-retest reliability of Aω _P and Aα _P. RESULTS: Linear regression models revealed that Aω _P , Aα _P , DFA _P , FCL _P had a significant relationship (p < 0.05) with impaired dorsiflexion function. Aα _P and DFA _P accounted for the most variance of dorsiflexion function. Aω _P , Aα _P , FCL _P , correlated significantly with all clinical outcome measures of walking ability. DFA _P 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 Aω _P and Aα _P . Correlation between FMA-LE and FCL _P was weaker than with Aω _P and Aα _P . Excellent test-retest reliability for both Aω _P (ICC = 0.968) and Aα _P (ICC = 0.947) was observed.
Significance: These results suggest that DFA _P may only be associated with dorsiflexion function during non-task specific isolated movements, but not during walking. FCL _P is associated with dorsiflexion function and walking ability measures but not as strongly as Aω _P and Aα _P possibly because FCL _P is influenced by contribution from hip and knee joint movements. Therefore, Aω _P and Aα _P are reliable measures and represent dorsiflexion function more accurately than DFA _P , and FCL _{P .}
Competing Interests: Declaration of Competing Interest The authors have no disclosures to report.
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