Woo Sub Kim, Dongjae Jeong, Moon Seok Park, Ki Hyuk Sung
After controlling for deformity severity, TC coalition was associated with reduced dynamic arch length range, while composite hindfoot kinematics were preserved, consistent with tibiotalar compensation for restricted subtalar motion.
BACKGROUND: Talocalcaneal (TC) coalition restricts subtalar motion and frequently coexists with hindfoot deformity, which may confound gait kinematic assessment. We evaluated multi-segment foot kinematics in TC coalition after controlling for deformity severity through radiological matching.
METHODS: Eighteen feet with TC coalition were matched 1:1 to no-coalition controls using anteroposterior talus-2nd metatarsal and lateral talus-1st metatarsal angles via Hungarian algorithm caliper matching. Multi-segment foot kinematics were compared using Welch's t-tests.
RESULTS: Demographic and radiographic characteristics were balanced between groups. Hindfoot, forefoot, and hallux kinematics did not differ significantly between groups (all p > 0.10). However, arch length range during gait was significantly reduced in TC coalition (15.1 ± 2.7 vs. 18.1 ± 3.2 mm; p = 0.005, Cohen's d = -1.01).
CONCLUSIONS: After controlling for deformity severity, TC coalition was associated with reduced dynamic arch length range, while composite hindfoot kinematics were preserved, consistent with tibiotalar compensation for restricted subtalar motion.