Exploratory analysis of the impact of age stratification on outcomes of combined Salter osteotomy and femoral osteotomy in pediatric developmental dysplasia of the hip using a 3-year cutoff

Abstract

Abstract Objective This study compared outcomes of combined Salter osteotomy, open reduction, and proximal femoral osteotomy in developmental dysplasia of the hip (DDH) children under 3 years versus those aged 3 years or older. Methods This retrospective study analyzed 65 DDH patients (aged 18 months to 6 years) who underwent the combined procedure between January 2010 and December 2020, stratified into < 3 years ( n = 34) and ≥ 3 years ( n = 31) groups. Evaluated parameters included radiographic measures, functional outcomes, and complications. Multivariable logistic regression adjusted for baseline differences in preoperative acetabular index. Results At a mean follow‑up of 8 ± 2.5 years, both groups demonstrated significant radiographic improvements ( P < 0.001), with the < 3 years group showing superior acetabular index and center‑edge angle changes ( P < 0.001). Final Severin grades were excellent/good in all patients, but the younger group had significantly more excellent results (97.1% vs. 74.2%, P = 0.002), and McKay excellent/good rates also favored the younger cohort (97.1% vs. 64.5%). Exploratory multivariable regression adjusting for preoperative acetabular index yielded unstable estimates with very wide confidence intervals (Severin OR = 20.92; McKay OR = 25.11, upper bounds > 400), making these findings hypothesis‑generating only. Due to quasi‑complete separation and sparse data, these estimates cannot be interpreted as confirmatory evidence of an independent age effect. Overall complications were comparable between groups (5.8% vs. 29.1%, P = 0.074), but avascular necrosis was significantly more frequent in the older group (12.9% vs. 0%, P < 0.05), suggesting a possible age‑related protective effect. The lack of significance in overall complications may reflect limited sample size and heterogeneity of events. Conclusion This combined procedure is effective for DDH. Patients under 3 years had better functional outcomes and lower AVN risk, but also milder baseline dysplasia. Multivariable adjustment suggested an age association, yet residual confounding and statistical instability precluded reliable quantification. Findings support early intervention, but do not prove causality.