Patients with unilateral ankle arthritis have decreased discrete and time-series limb symmetry compared to healthy controls

Abstract

Patients with ankle arthritis (AA) have side-to-side limb differences at the ankle and in spatiotemporal measures; however, the degree of symmetry between limbs has not been compared to a healthy population. The purpose of this study was to determine differences in limb symmetry during walking for discrete and time-series measures when comparing patients with unilateral AA to healthy participants. Thirty-seven AA and 37 healthy participants were age, gender, and body mass index matched. Three-dimensional gait mechanics and ground reaction force (GRF) were captured during four to seven walking trails. GRF and hip and ankle mechanics were extracted bilaterally for each trial. The Normalized Symmetry Index and Statistical Parameter Mapping were used to assess discrete and time-series symmetry, respectively. Discrete symmetry was analyzed using linear mixed-effect models to determine significant differences between groups (α = 0.05). Compared to healthy participants, patients with AA had decreased weight acceptance (p = 0.017) and propulsive (p < 0.001) GRF, ankle plantarflexion (p = 0.021), ankle dorsiflexion (p = 0.010), and ankle plantarflexion moment (p < 0.001) symmetry. Significant regions of difference were found between limbs and groups throughout the stance phase for the vertical GRF force (p < 0.001), the ankle angle during push-off (p = 0.047), the plantarflexion moment (p < 0.001), and the hip extension angle (p = 0.034) and moment (p = 0.010). Patients with AA have decreased symmetry in the vertical GRF and at the ankle and hip during the weight acceptance and propulsive portions of the stance phase. Therefore, clinicians should try a non improving symmetry focusing on changing hip and ankle mechanics during the weight acceptance and propulsive phases of gait.

Keywords: ankle arthritis; asymmetry; gait mechanics; limb symmetry; walking speed.