Hip-shelf procedure in the treatment of osteonecrosis of the transpositioned acetabulum after rotational acetabular osteotomy

Necrosis of the transpositioned acetabulum after rotational acetabular osteotomy (RAO) is a major complication characteristic of this procedure. This complication, although rare, has been thought difficult to treat. We report a patient with acetabular osteonecrosis and subsequent collapse after RAO that was effectively treated with a shelf operation, providing satisfactory remodeling of the hip joint. A 16-year-old female had undergone RAO for the treatment of developmental acetabular dysplasia. Postoperative radiography showed that the osteotomized acetabular fragment was unusually thin, and that the osteotome entered the hip joint during the surgery. Five months after the RAO, X-rays revealed significant collapse of the transpositioned acetabulum, and femoral head subluxation caused by postoperative osteonecrosis. Seven months after the RAO, the patient underwent a hip-shelf procedure. The remaining acetabular fragment was used in this procedure, according to the Spitzy method. Seven years after the second operation, favorable remodeling of the hip joint was observed; however, early osteoarthritic changes, including slight joint space narrowing, bone sclerosis of the new acetabulum, and bone cysts within the femoral head, were seen.