Surgical Outcomes of Developmental Dysplasia of the Hip with or Without Prior Failed Closed Reduction

Background: Osteonecrosis of the femoral head is a major complication in the treatment of developmental dysplasia of the hip (DDH). Redislocation and secondary surgeries were regarded as risk factors of osteonecrosis. This study aims to clarify whether prior failed closed reduction is a risk factor of osteonecrosis in subsequent surgery. Methods: We retrospectively studied 124 patients treated by open reduction and pelvic osteotomy for unilateral DDH before 3 years old. Twenty-five patients had failed closed reduction before the surgery (secondary surgery group), and the other 99 patients had the same surgery as the first treatment (primary surgery group). Osteonecrosis was defined by broadening of femoral neck and fragmentation of epiphysis in the first 3 years after operation. The background data and rate of osteonecrosis were compared between the 2 groups using t test and χ 2 test. Results: Age at surgery and Tönnis grade were not significantly different between the 2 groups. Broadening of the femoral neck was observed in 63 of the 99 hips (63.6%) in the primary surgery group and 7 of the 25 hips (28.0%) in the secondary surgery group (P=0.001). Rate of epiphyseal fragmentation was 34% in primary surgery group and 24% in secondary surgery group (P=0.323). Conclusions: Soft tissue tension could be reduced by previous closed reduction, and redislocation would not carry a greater risk of osteonecrosis in the subsequent open reduction. Level of Evidence: Level III - therapeutic study.