Radiological outcomes in late-onset Perthes after femoral varus osteotomy.

PURPOSE: Treatment of late-onset Legg-Calvé-Perthes disease (LCPD) remains challenging, with outcomes varying by age and extent of involvement. This study aimed to evaluate the radiological outcomes following femoral varus osteotomy (FVO) in children presenting with LCPD after 8 years of age, to determine whether containment surgery provides benefit even in older children. METHODS: We retrospectively reviewed patients aged > 8 years with LCPD who underwent FVO between January 2008 and April 2019 at our institution, with a minimum two-year radiographic follow-up. Disease severity was graded using the modified Elizabethtown classification, Herring’s lateral pillar classification, and epiphyseal quotient (EQ). Radiographic outcomes at the latest follow-up were assessed using Deformity Index (DI), Caput Index (CI), Epiphyseal Extrusion Index (EEI), Sphericity Deviation Score (SDS), and Stulberg classification. Correlation analysis was performed using Spearman’s rank correlation. RESULTS: Twenty-seven children (22 boys, 5 girls; mean age 9.6 years, range 8.3–11.9) were included, with a median follow-up of 3.1 years (range 2–11). The mean DI was 0.31 (range 0.08–0.63) and showed a moderate positive correlation with the modified Stulberg grade (ρ = 0.57, p < 0.05). Fourteen of 27 hips (52%) achieved a DI < 0.3 at final follow-up. A lower postoperative EEI (p < 0.001) and lesser degree of lateral pillar collapse (p = 0.01) were significantly associated with improved femoral head sphericity. CONCLUSION: The Herring classification and postoperative EEI significantly correlated with final femoral head sphericity. Containment by FVO in children presenting after 8 years of age results in good radiological outcomes in over half (50%) of cases, indicating that age alone should not preclude surgical containment in late-onset LCPD. LEVEL OF EVIDENCE: Level III retrospective therapeutic study.