We report an intertrochanteric fracture in a patient who had undergone hip arthrodesis 30 years previously. A 53-year-old man was injured in a head-on car crash and was referred to our hospital for treatment. Plain radiographs showed an intertrochanteric fracture of the right proximal femur and deformity of the right hip joint. He had undergone hip arthrodesis surgery 30 years previously at another hospital. Computed tomography scan showed marked atrophy of the gluteus and iliopsoas muscles. He preferred undergoing total hip arthroplasty (THA) to internal fixation. THA was performed using the anterolateral approach with the patient in the supine position as he had undergone hip arthrodesis through the Smith–Petersen approach, and we were concerned about damaging the gluteus muscle and dislocation if we took the posterolateral approach. The femoral head was removed using curved chisels under fluoroscopy. A cementless THA (J Taper stem, Aquala polyethylene liner; Kyocera Medical Corporation, Osaka, Japan) was inserted and fixed appropriately. Full weight-bearing using a walking frame was allowed 2 weeks after the surgery. Six months after the operation, he was able to walk independently and had good range of movement of the hip joint but continued to have weakness in the abductor muscles.

Very few cases of proximal femur fracture in a previously arthrodesed hip have been reported. Manzotti et al. reported a similar case but they performed open reduction and internal fixation. No previous reports in the literature describe THA for intertrochanteric fracture in an arthrodesed hip. The conversion of an arthrodesed hip to THA is technically challenging. It has a high risk of complications such as nerve injuries and hip instability. We were able to treat the patient successfully, but surgeons should carefully decide the treatment method depending on the case.