Three-dimensional gait analysis for assessing dynamic ankle spasticity after stroke.

BACKGROUND: Dynamic ankle spasticity during walking is a common complication after stroke. It remains unclear which clinical indicators predict dynamic spasticity and whether three-dimensional (3D) gait parameters can reflect its severity. METHODS: 3D gait analysis data were obtained from 42 patients with dynamic spasticity and a 1:1 propensity score-matched control group. Spasticity was assessed using the Modified Tardieu Scale (MTS). Dynamic kinematic and spatiotemporal gait indicators were analyzed. Spearman correlation analysis was performed to examine associations between gait parameters and MTS scores. A binary logistic regression model (Model 1) was constructed to identify factors associated with dynamic spasticity using gait-related physical assessments and ankle kinematics, with stepwise backward elimination applied. For severity evaluation, an ordinal logistic regression model (Model 2) was built using the MTS X score as the dependent variable. RESULTS: Compared to controls, the spasticity group showed slower gait speed, shorter step length, and longer double support time. In Model 1, reduced ankle plantarflexion angle and weaker dorsiflexor strength were independently associated with the presence of dynamic spasticity. In Model 2, prolonged double support time on the affected side was significantly associated with dynamic spasticity severity. CONCLUSION: Reduced plantarflexion angle and dorsiflexor weakness are key clinical factors associated with walking-related dynamic spasticity, and prolonged double support time may serve as a quantifiable indicator of its severity. These findings support the potential value of 3D gait analysis in identifying and characterizing dynamic spasticity after stroke.