Treatment of developmental dysplasia of the hip after failed open reduction.

It is difficult to obtain a good result by secondary open reduction if a primary open reduction for developmental dysplasia of the hip (DDH) fails. Complications such as avascular necrosis of the femoral head and subluxation of the hip are common. In this study, we retrospectively reviewed the causes of failure of primary open reduction and the final clinical and radiographic outcomes of 32 patients (34 hips) with DDH who underwent repeat open reduction and other procedures from January 1982 to December 1995. The ages of the patients at the time of the secondary operation ranged from 1.5 to 16.5 years (mean, 5.9 yr). The interval from the primary open reduction to the secondary procedure ranged from 3 days to 10 years (mean, 8.9 mo). In most cases (30 hips), the position of the redislocated femoral head was Tönnis grade 3 or 4. Avascular necrosis of the femoral head was evident in about half of the hips before the secondary open reduction. The most common cause of failure of the primary operation was a tight inferior capsule and transverse acetabular ligament, which blocked complete reduction. At a mean follow-up period of 42 months (range, 24-147 mo) after the secondary operation, the radiographic classification was Severin class 1 or 2 in 15 of the 34 hips, and Severin class 3 or worse in the remaining 19 hips. Clinically, according to the modified McKay criteria, 18 of the 32 patients (18 hips) had excellent or good results, and three patients (four hips) had poor results. In conclusion, the main cause of failure of the primary open reduction of DDH was technical error. We believe that detailed preoperative evaluation is critical for the success of primary open reduction of DDH.