Which factors are associated with failure of conservative treatment in progressive collapsing foot deformity?

BACKGROUND: Progressive collapsing foot deformity (PCFD) has a variable course, with over 10% of patients progressing to surgery despite nonoperative treatment. METHODS: Adults with PCFD initially treated nonoperatively and baseline weight-bearing CT were retrospectively stratified into nonoperative and surgical groups. Demographics, PROMIS, and WBCT alignment were compared. RESULTS: Seventy-six feet were analyzed. Progression to surgery was associated with greater baseline hindfoot malalignment (Foot-Ankle Offset 9.0 ± 3.1 vs 6.6 ± 3.0, p = 0.046; Hindfoot Moment Arm p = 0.008), male sex (p = 0.008), and higher BMI (32.1 ± 7.3 vs 26.8 ± 5.2, p = 0.044). PROMIS and forefoot alignment did not discriminate outcomes. CONCLUSION: In this exploratory cohort, a more valgus hindfoot alignment, male sex, and higher BMI emerged as potential predictors of failure of nonoperative treatment in PCFD, whereas baseline pain and physical function did not discriminate outcomes. These candidate factors warrant confirmation in larger, adequately powered studies before WBCT-derived alignment parameters can be used for risk stratification. LEVEL OF EVIDENCE: Level III - Retrospective comparative study.