The role of gender in patients with developmental dysplasia of the hip treated with closed reduction and spica cast immobilization: does it affect prognosis?

To investigate the impact of gender on the prognosis of children with developmental dysplasia of the hip (DDH) treated with closed reduction and spica cast immobilization (CR-SCI). A retrospective analysis was conducted on 302 DDH children (347 hips) who underwent CR-SCI at our department from 1 January 2003 to 31 December 2015. Among them, 42 cases (50 hips) were male, and 260 cases (297 hips) were female. The acetabular index, center edge angle (CEA), and avascular necrosis (AVN) of the femoral head were measured and evaluated on anteroposterior pelvic radiographs. The Severin classification was recorded at the final follow-up. Preoperative analysis of acetabular index revealed poorer hip development in females than in males (P = 0.003). However, last follow-up acetabular index, acetabular index improvement, and last follow-up CEA were comparable for both sexes (P > 0.05). There were no statistically significant differences in postoperative re-dislocation rates, reoperation rates, or Severin classification at the final follow-up (P > 0.05). However, significant differences were observed in the incidence of AVN (P = 0.025) and AVN grading (P = 0.046) at the final follow-up. Further univariate analysis showed that gender significantly influenced AVN (P = 0.025). Multivariate analysis revealed that gender (P = 0.005) and adductor tenotomy (P = 0.028) were influencing factors for AVN. Gender is an influencing factor for AVN after CR-SCI for DDH, with male children having a higher probability of developing AVN postoperatively, indicating poorer outcomes despite no significant differences in postoperative imaging and functional outcomes between genders. Intraoperative adductor tenotomy is another risk factor for AVN. Level of Evidence: Level IV-retrospective cohort study.