We questioned whether our modified soft tissue surgical procedure can provide acceptable results with lower complication rates in developmental dysplasia of the hip (DDH). We retrospectively reviewed 143 patients (185 hips) with a mean age of 11.6 months at operation and a minimum followup of 5 years (mean, 7.5 years; range, 5-13 years). We used a posteromedial approach and sectioned the adductor longus and iliopsoas tendons. If we achieved an arthrographically documented anatomic reduction we closed the incisions; if not, we made an arthrotomy to obtain an anatomic reduction through the same incision at the same session. A hip score indicating an acceptable outcome was obtained in 168 hips (90.8%). We identified osteonecrosis of the femoral head (ON) in 36 (19.5%) hips and redislocation in four (2.2%). Both the ossific nucleus and physis were affected in 10 of the 36 hips with ON. We performed secondary operations in 12 hips (6.5%). Hips of the infants after walking age and hips with higher preoperative dislocation grades, acetabular indices, and ON were more prone to having lower hip scores. Based on the data, we believe routine arthrotomy is not needed during posteromedial surgery in DDH and this modified procedure was safe and effective.