EP1.73 Three-dimensional Acetabular Containment Surgery Improves Femoral Head Morphology and Clinical Outcomes in Older Children with Legg-Calvé-Perthes Perthes Disease

Abstract Background Legg-Calvé-Perthes disease (LCPD) in older children (≥6 years) presents unique therapeutic challenges due to limited remodeling potential and high risk of permanent deformity. While various surgical interventions exist, the optimal treatment strategy for patients with substantial femoral head subluxation remains controversial. Traditional containment procedures often fail to provide adequate three-dimensional coverage when femoral epiphyseal extrusion index exceeds 20%. Questions: We asked: (1) Can triple pelvic osteotomy and periacetabular osteotomy provide three-dimensional improvement in acetabular coverage for older LCPD patients with high femoral epiphyseal extrusion index? (2) How does the morphology of the acetabulum and femoral head evolve postoperatively? (3) What are the clinical and functional outcomes following these procedures? Methods We retrospectively reviewed 10 patients (10 hips; mean age, 9.12 years; range, 6-13 years) who underwent either triple pelvic osteotomy (n=7) or periacetabular osteotomy (n=3) between 2015 and 2023. All patients had femoral epiphyseal extrusion index >20% and minimum follow-up of 12 months (mean, 60.1 months; range, 15.6-105.8 months). We assessed three-dimensional coverage using lateral center-edge angle (LCEA), anterior center-edge angle (ACEA), Tönnis angle, and femoral epiphyseal extrusion index. Femoral head morphology was evaluated using modified sphericity deviation score and Stulberg classification. Clinical outcomes were measured using modified Harris Hip Score and McKay classification. Results Both procedures significantly improved three-dimensional coverage: LCEA increased from 10.8° ± 1.8° to 36.1° ± 3.2° (p<0.001), ACEA from 25.7° ± 2.8° to 39.9° ± 3.8° (p=0.008), and femoral epiphyseal extrusion index decreased from 29.9% ± 3.0% to 5.3% ± 3.3% (p=0.001). The mean postoperative modified sphericity deviation score was 8.5% (range, 0-30.5%). At final follow-up, 9 hips (90%) achieved Stulberg I/II classification. The modified Harris Hip Score improved from 79.0 ± 2.4 to 95.1 ± 1.2 (p<0.001), with 80% of patients achieving excellent McKay functional outcomes. Multivariate analysis revealed significant correlations between postoperative sphericity and preoperative Herring classification (p=0.035), postoperative LCEA (p=0.05), ACEA (p=0.003), and BMI (p=0.042).