Introduction and Objectives: We compared the clinical and radiographic results of patients with JRA and primary arthritis using a non-cemented THR with an alumina-alumina THA.

Materials and Methods: We studied 29 THR (Cerafit cup and Multicone stem) implanted in 19 patients with JRA in group 1 and 135 with primary arthritis in group 2. Mean follow-up was 59.0 months. It was seen that 13 hips in group 1 had moderate-severe acetabular protrusion and allograft was used in 12 hips. The center of rotation was determined pre and postoperatively in group 1 according to Ranawat.

Results: In group 1 age (p< 0.001), weight (p< 0.001), and level of activity (p< 0.001) were less. Type A acetabulum (p=0.014) and a cylindrical femur (p< 0.01), according to Dorr, were more frequent in group 1. There was no noise or alumina breakage. There were two intraoperative femur fractures in group 1. There was a revision of 1 cup in group 1 and infection of 1 stem in group 2. In most of the group 1 cases anatomical position was recovered (p< 0.001). The preoperative center of rotation of the hip with acetabular protrusion was 23.2 mm and in the postoperative X-ray 5.6 mm.

Discussion and Conclusions: In spite of the differences, THR with alumina-alumina allows similar results to be obtained in the medium term in patients with JRA. The use of an allograft in those patients with severe acetabular protrusion makes it possible to reconstruct the center of rotation of the hip.

Introduction and Objectives: We compared the clinical and radiological results in patients under and over 40 years of age who had received a non-cemented alumina-alumina hip replacement.

Materials and Methods: We studied 337 Cerafit acetabular cups implanted in 4 hospitals in association with Multicone-Hydroxyapatite stems with alumina-alumina bearing surfaces. Group 1 consisted of 63 patients under 40 years of age and group 2 of 274 patients over 40 years of age. Mean follow-up was 59.0 months. Demographic data and clinical and radiological results of both groups were compared.

Results: There were no cases of primary arthritis in group 1, however severe hip dysplasia and juvenile rheumatoid arthritis were frequent (p< 0.001). Weight (p< 0.001) and degree of activity (p=0.003) were greater in group 2. Preoperative function (p=0.03) and mobility (p< 0.001) were worse in group 1. There were 3 cup revisions in group 1 and 4 (including an alumina breakage) in group 2. Survival with no revision due to any cause was 91.4+5.1% in group 1 and 97.0+ 1.1 in group 2 (p=0.4007). There were no noises. Clinical and radiological results were similar in both groups.

Discussion and Conclusions: Diagnoses were different in both groups, the younger patients were in worse conditions. In spite of these differences, the alumina-alumina prosthesis showed similar results in both groups in the medium term. Long-term follow-ups are necessary to confirm these results.