Hindfoot Motion Analysis by Subtalar Compensation and Ankle Osteoarthritis Stage using a 3D Multi- Segment Foot Model

CATEGORY: Hindfoot INTRODUCTION/PURPOSE: Biomechanics of the hindfoot in ankle osteoarthritis (OA) have not yet fully understood. We aimed to identify hindfoot motions by gait analysis using multi-segment foot model (MFM) according to the stage of ankle OA or hindfoot alignment determined by the presence of subtalar compensation. METHODS: We retrospectively reviewed the medical records, simple radiographs, and gait MFM data from 54 ankles which admitted to our hospital for the treatment of advanced ankle OA. Spatiotemporal gait parameters and 3-dimensional motions of hindfoot segment were analyzed according to sex, age, body mass index, the Takakura classification, and the presence of subtalar compensation. RESULTS: As a result, all spatiotemporal gait parameters showed no significant difference according to the presence of subtalar compensation and the stage of ankle OA. With regard to the relationship between hindfoot segmental motion and the stage of ankle OA, only normalized step width was significantly different from each other (p value=0.028). Average motion of hindfoot (decompensation versus compensation) showed no significant difference in sagittal and transverse plane. In coronal movement of hindfoot, there were collapsed curves in both groups, which had constant significant difference. In comparison of 3a, 3b, and 4 stages of Takakura, more advanced 3b stages of ankle OA had the smaller sagittal range of motion compared to 3a (p value=0.028). Coronal movement of hindfoot in Takakura 3a/3b/4 all showed relatively flat pattern. CONCLUSION: In conclusion, spatiotemporal parameters were not affected by the alignment state of the heel resulted from subtalar compensation. Sagittal range of hindfoot motion decreased in the advanced ankle OA. Coronal movement of subtalar joint in ankle OA, once it was disrupted, showed no change regardless of the stage of ankle OA or compensation state of the hindfoot.