Comparison of subtrochanteric varus osteotomy and shelf acetabuloplasty in fragmentation-stage (Waldenström stage II) Legg-Calvé-Perthes disease: a prospective randomized study.

Abstract

Purpose: Optimal containment in fragmentation stage (Waldenström stage II) of Legg-Calvé-Perthes disease (LCPD) remains controversial. This study compared the clinical and radiographic outcomes of subtrochanteric femoral varus osteotomy (STVO) versus shelf acetabuloplasty in children with fragmentation stage (Waldenström stage II) of LCPD.

Methods: This prospective randomized clinical trial included 32 children (32 hips) with LCPD in fragmentation stage (Waldenström stage II), treated between April 2022 and June 2024. Patients were randomized into two groups: STVO (n = 16) and shelf acetabuloplasty (n = 16). The primary outcome was clinical outcome at final follow-up assessed using the modified Sundt criteria. Secondary outcomes included containment radiographic parameters, interim femoral head sphericity using the Stulberg classification, leg length discrepancy (LLD), and complications. Mean follow-up duration was 25.1 ± 1.8 months in the STVO group and 26.1 ± 2.0 months in the shelf acetabuloplasty group.

Results: Both procedures resulted in significant clinical and radiographic improvement. Good clinical outcomes were achieved in 81.2% of hips in each group, with no poor outcomes. At final follow-up, the mean center-edge angle (CEA) increased significantly in both groups, reflecting improved lateral femoral head coverage. Sharp's angle decreased significantly in both groups, indicating improved acetabular morphology. Both groups demonstrated a significant reduction in the medial joint space ratio, indicating improved containment. After adjustment for baseline values using ANCOVA, no statistically significant between-group differences were identified. Among hips that had reached the remodeling stage, exploratory analysis suggested a higher proportion of favorable interim Stulberg outcomes (I-II) in the STVO group; however, interpretation is limited by the small subgroup size, differential progression to remodeling, and the use of a classification system originally intended for assessment at skeletal maturity. Clinically significant LLD (> 1.5 cm) occurred in 43.8% of STVO patients and in none of the shelf group. Complications were minor and comparable.

Conclusion: STVO and shelf acetabuloplasty yield comparable short- to mid-term clinical outcomes in fragmentation stage (Waldenström stage II) of LCPD. However, STVO was associated with a substantially higher incidence of clinically significant leg length discrepancy, whereas shelf acetabuloplasty preserved limb length. Exploratory analyses suggested a possible advantage of STVO regarding interim femoral head sphericity. These findings should not be interpreted as evidence of superiority, and require confirmation at skeletal maturity.