Factors Associated With Flat-Top Talus in Radiographically Evaluated Ponseti-Treated Clubfeet

INTRODUCTION: Flat-top talus (FTT) is a recognized sequela of clubfoot associated with stiffness and early ankle degeneration. However, its frequency after Ponseti treatment and associated clinical and treatment-related factors remain poorly defined. This study aimed to identify clinical and treatment-related factors associated with FTT in Ponseti-treated clubfeet. METHODS: We performed a retrospective dual-center cohort study (2005 to 2023) of children with idiopathic and non-idiopathic clubfoot treated using the Ponseti method who had at least one adequate lateral radiograph for evaluation. Talar morphology was classified qualitatively (flat vs. round) by independent blinded raters. Clinical variables and treatment exposures were analyzed at the foot level, and univariate logistic regression identified factors associated with FTT. RESULTS: Ninety-eight patients (152 feet) met inclusion criteria. FTT was identified in 104 of 152 radiographically evaluated feet (68%). Higher Pirani score at diagnosis was associated with increased odds of FTT (OR: 1.58, 95% CI: 1.09-2.48; P=0.027). Feet with FTT demonstrated more limited pre-tenotomy dorsiflexion (P=0.034 in idiopathic feet). Greater cumulative casting exposure was associated with FTT, including ≥13 corrective casts before imaging (OR: 2.72, 95% CI: 1.06-7.15; P=0.038). In site-specific analysis, each additional cast increased the odds of FTT by 13% (OR: 1.13, 95% CI: 1.03-1.27; P=0.020), and surgery before imaging was associated with increased odds of FTT (OR: 4.29, 95% CI: 1.40-14.50; P=0.013). Relapse rates after radiographic detection did not differ significantly between groups. CONCLUSIONS: FTT in Ponseti-treated clubfeet undergoing radiographic evaluation is associated with greater baseline deformity severity, cumulative casting exposure, and prior surgery. FTT seems to represent a marker of intrinsic rigidity and treatment burden rather than an independent driver of recurrence. Recognition of these associated factors may assist clinicians in monitoring talar morphology and counseling families regarding possible long-term limitations in ankle dorsiflexion. LEVEL OF EVIDENCE: Level III-Retrospective cohort study.