Comparison of Open and Closed Reduction for Developmental Dysplasia of the Hip: A Retrospective Evaluation of Acetabular Development and Complications

Background/Objectives: Developmental dysplasia of the hip (DDH) is a common pediatric musculoskeletal disorder, and the optimal treatment approach remains controversial. This study compared open and closed reduction in terms of acetabular development, avascular necrosis (AVN) of the femoral head, and the need for subsequent pelvic osteotomy. Methods: This retrospective cohort study evaluated 75 patients (95 hips; 48 right, 47 left) treated for DDH at a tertiary referral center. We performed open reduction in 63 hips and closed reduction in 32. We performed arthrography in 50 hips (52.6%) with a positive Ortolani test to assess reduction quality. We assessed acetabular remodeling using the acetabular index (AI) at 6, 12, and 36 months postoperatively. Dislocation severity was graded using the Tönnis classification, and AVN was assessed using the Kalamchi–MacEwen criteria. Statistical analyses included chi-square tests, independent-samples t-tests, one-way ANOVAs, and Pearson correlation tests, with significance set at p < 0.05. Results: The mean age at surgery was 12.83 ± 5.13 months (range: 6–24 months), and the mean follow-up was 37.78 ± 8.07 months (range: 36–60 months). AVN was observed in 7/63 hips (11.1%) after open reduction and in 0/32 hips after closed reduction (two-sided Fisher exact test, p = 0.091). Among the seven AVN-affected hips, four were Kalamchi–MacEwen grade I, two were grade II, and one was grade III; no grade IV case was observed. Secondary pelvic osteotomy was performed in 13/63 hips (20.6%) after open reduction and 2/32 hips (6.3%) after closed reduction. AI improved during follow-up, decreasing from 38.31 ± 4.47° at 6 months to 31.59 ± 4.28° at 12 months and 23.65 ± 6.03° at 36 months. Higher Tönnis grades were associated with higher 36-month AI values (p = 0.018). Older age at surgery correlated positively with AI at 12 months (p = 0.038) and 36 months (p < 0.001). Conclusions: Open reduction was associated with higher rates of AVN and secondary pelvic osteotomy; however, treatment selection was based on reducibility and arthrographic findings, precluding causal interpretation. Older age at treatment and greater dislocation severity were associated with less favorable acetabular remodeling. Arthrography-assisted closed reduction remains a reasonable option when a stable concentric reduction is achievable, although neither method demonstrated clear superiority.