Differences in Intersegmental Foot and Ankle Motion Between Patients With Varus and Valgus Ankle Osteoarthritis.

In instances of ankle osteoarthritis (OA), a significant proportion of patients exhibit varus ankle OA, while valgus ankle OA is less commonly seen. Both types employ distinct compensatory mechanisms to sustain a plantigrade gait. This study explored the variations in intersegmental foot and ankle motions between patients with varus and valgus ankle OA using multisegment foot gait analysis. The study included 55 patients with varus and 13 with valgus end-stage ankle OA. The DuPont foot model was utilized to evaluate intersegmental foot and ankle kinematics, and temporospatial gait parameters were also analyzed. Both groups displayed comparable temporospatial parameters. Notably, the varus ankle OA group showed significantly reduced sagittal range of motion (ROM) in both the forefoot and hindfoot but increased coronal ROM in the forefoot compared to their counterparts. The valgus ankle OA group demonstrated a significantly greater hindfoot coronal ROM compared to the varus ankle OA group. The varus ankle OA group exhibited significant hallux dorsiflexion during the terminal stance phase. In addition, the varus ankle OA group demonstrated significant forefoot plantar flexion and adduction during the stance phase and forefoot eversion throughout the gait cycle. In contrast, the valgus ankle OA group showed significant hindfoot eversion throughout the gait cycle and hindfoot dorsiflexion during the terminal stance phase. Although both groups displayed similar absolute talar tilt angles, distinct differences in the ROM and intersegmental positions highlighted unique compensatory mechanisms, emphasizing the value of kinematic analysis in assessing functional adaptations related to coronal alignment.