Joint space wider than 2 mm is essential for an eccentric rotational acetabular osteotomy for adult hip dysplasia

Satisfactory intermediate-term results after an eccentric rotational acetabular osteotomy (ERAO) for the treatment of early osteoarthritis secondary to developmental dysplasia of the hip (DDH) have been reported. The purpose of this study was to investigate whether a minimum joint space width (JSW) in patients with advanced osteoarthritis secondary to DDH influences intermediate-term clinical and radiographic outcomes after performing an ERAO. A total of 113 patients (116 hips) with a JSW of a parts per thousand currency sign3 mm were consecutively treated by ERAO for advanced osteoarthritis of the hip and then were followed for more than 5 years. Based on the preoperative JSW, the patients were divided into three groups: minimum JSW of a parts per thousand currency sign1 mm (JS1 group); JSW > 1 mm but a parts per thousand currency sign2 mm (JS2 group); JSW > 2 mm but a parts per thousand currency sign3 mm (JS3 group). The average ages of the JS1, JS2, and JS3 patients were 40, 44, and 43 years, respectively. The average follow-up period was 10.6 years. Overall conversion to total hip arthroplasty (THA) was performed in 14 joints. According to a Kaplan-Meier survivorship analysis at 15 years after the index operation, 96% of the patients with a JSW of > 2 mm (JS3 group) did not require conversion to THA. A JSW of > 2 mm before surgery is considered essential to obtain an excellent intermediate-term result following performance of an ERAO.