Modified Pemberton osteotomy for developmental dysplasia of the hip in children: a mid- to long-term follow-up study

Background and objective Developmental dysplasia of the hip (DDH) is a common pediatric condition requiring timely surgical intervention in older children. Conventional Pemberton osteotomy, while effective, carries a risk of iatrogenic injury to the triradiate cartilage due to its blind deep-pericapsular trajectory. The modified Pemberton osteotomy (MPO) shifts the osteotomy endpoint to 3–5 mm above the sciatic notch, creating a greenstick hinge above the Y-shaped cartilage to avoid growth-plate damage. This study aimed to evaluate the mid- to long-term efficacy and safety of MPO in children with DDH over a minimum follow-up of 5 years. Materials and methods We retrospectively reviewed 55 patients (71 hips) who underwent open reduction combined with MPO between May 2004 and June 2025. Radiographic parameters included acetabular index (AI), central-edge angle (CEA), and Reimer index (RI). Clinical and radiographic outcomes were assessed using McKay criteria and Severin classification, respectively. Results The mean follow-up duration was 7.21±1.64 years. The mean AI improved from 39.66 ± 5.46° preoperatively to 12.71 ± 8.37° at final follow-up, demonstrating powerful and stable acetabular remodeling capacity. According to the McKay clinical criteria, highly satisfactory functional outcomes were achieved, with an excellent-good rate of 88.7% (63/71 hips). Radiographic assessment using the Severin classification confirmed excellent joint congruence, yielding an excellent-good rate of 93.0% (66/71 hips). Avascular necrosis (AVN) occurred in 8 hips (11.2%), which is a low and acceptable incidence compared to historical pelvic osteotomies. Conclusion MPO provides favorable and durable mid- to long-term clinical and radiographic outcomes for DDH in children. By avoiding iatrogenic injury to the triradiate cartilage, MPO offers improved surgical safety compared with conventional Pemberton osteotomy, with an acceptable AVN rate directly attributable to the procedure.