BACKGROUND This study aimed at identifying early risk factors for rigid relapse in idiopathic clubfoot using foot radiographs. METHODS Thirty-four patients with 43 idiopathic clubfeet treated with the Ponseti method were retrospectively reviewed. RESULTS There were seven rigid relapse recalcitrant to manipulation and requiring extensive soft-tissue release. Three radiograabphic measurements on the maximum dorsiflexion lateral (MD-Lat) radiograph, talocalcaneal (TaloCalc-Lat), tibiocalcaneal (TibCalc-Lat), and calcaneus-first metatarsal (CalcMT1-Lat) angles, showed significant differences between patients with and without rigid relapse. The TaloCalc-Lat and CalcMT1-Lat angles showed significant hazard ratio for rigid relapse by multivariate survival analysis. Clubfeet demonstrating TibCalc-Lat>90° and CalcMT1-Lat<5° have a 24.9-fold odds ratio to develop rigid relapse compared to those demonstrating TibCalc-Lat≤90° or CalcMT1-Lat≥5°. CONCLUSIONS The TaloCalc-Lat, TibCalc-Lat, and CalcMT1-Lat angles on the MD-Lat radiograph immediately before the tenotomy, probably representing intrinsic tightness of the midfoot and/or hindfoot, are significant risk factors for rigid relapse in patients treated with the Ponseti method.