Factors influencing outcomes of pelvic osteotomy for residual acetabular dysplasia following closed reduction in patients with developmental dysplasia of the hip.

To investigate the factors influencing outcome of pelvic osteotomy (PO) for residual acetabular dysplasia (RAD) following closed reduction (CR) in patients with developmental dysplasia of the hip (DDH). We retrospectively reviewed 91 patients (95 hips) with DDH who underwent PO for RAD. Tönnis grade, Acetabular index, Center Edge Angle, Reimer's Index (RI), and avascular necrosis of the femoral head (AVN) were assessed. Hips were divided into satisfactory (Severin I/II) and unsatisfactory group (Severin III/IV). Finally, 87 hips (91.5%) had satisfactory and 8 (8.5%) unsatisfactory outcomes. The RI before PO was significantly higher in unsatisfactory (49.6 ± 9%) than in satisfactory group (30.6%±11.8%). All patients without AVN had satisfactory outcome, while it was 78.9% of patients with AVN. Logistic regression analysis showed that higher AVN grade and RI before PO were risk factors for unsatisfactory outcome. Satisfactory outcome was obtained in all hips with RI < 33% before PO, while it was 79.5% if RI > 33% before PO (79.5%). There was no difference in the satisfactory rate between patients undergoing open reduction (66.7%) and those not undergoing (83.3%). The rate of satisfactory outcome in patients undergoing femoral osteotomy (63.6%) was lower than those without it (100%). In patients with RAD following CR, good outcome can be expected after PO alone. AVN and preoperative RI > 33% are risk factors for poor outcome. Additional open reduction and femoral osteotomy do not significantly improve outcome of PO in patients with preoperative RI > 33%.