HIP RESURFACING ARTHROPLASTY FOR OSTEONECROSIS OF THE FEMORAL HEAD - LESSONS AFTER 5 TO 11-YEARS OF EXPERIENCE

Introduction Hip resurfacing arthroplasty (HRA) with metal-on-metal bearing is currently emerging as a major evolution of hip arthroplasty. It could be an alternative to total hip arthroplasty. HRA also may allow young patients to perform high sports activities. It preserves proximal femoral bone stock and keeps the medullary canal intact. A large diameter of the femoral head provides wider range of the hip motion. Incidence of dislocation is very low. Most of HRA have been reported for young patients with stage of osteoarthritis. But, reports of HRA for osteonecrosis of the femoral head (ONFH) are rare and the outcomes are uncertain. Methods This study was performed to introduce our indication and technique of HRA for the patients with ONFH and to assess the outcomes after a minimum 5-year follow up. After the biomechanical study, we set our own indications for HRA as follows: when the size of a lesion was less than 50% of the entire head and the rim at the head-neck junction was intact at least to a 5 mm above from the head-neck junction. From December 1998 to July 2004; 157 hips (139 patients) underwent HRA under the diagnosis of ONFH. Their mean age was 37 years. One hundred and fourteen hips were in men and 25 hips were in women. The average follow-up period was 88 months (range, 60 to 128 months). Clinical outcomes were evaluated with Harris Hip Scores, hip or thigh pain, limb length discrepancy, and range of motion. As a radiological evaluation, the preoperative size and staging of the lesion, patterns of bone remodeling, and complications such as femoral neck fracture, neck narrowing, loosening, and osteolysis were analyzed. Results Sixty-two percent of the hips were staged as Steinberg IV or more. The size of the necrotic lesion in magnetic resonance imaging ranged from 23 to 50%. The Harris Hip Score increased from 77 points pre-operatively to 98 points at the final visit. All range of motions significantly improved after the operation. No patient complained of limb length discrepancy. Twenty-eight hips showed painless radiographic changes including impingement (22 hips), focal radiolucency (4 hips), and neck narrowing (2 hips). All patients showed no clinical symptoms. There was no detectable wear, dislocation, femoral neck fracture, or other complications. No revision or additional surgery was required in all patients. Conclusion Even for the patients with ONFH, the overall minimum 5-year outcomes of HRA are promising and superior to other reports of conventional THA. Patient satisfaction is extremely high. A strict application of indications and meticulous surgical technique are critical for these successful results.