Total hip replacement in younger patients - Survival rate after avascular necrosis of the femoral head

Background A high risk of loosening has been reported in replacements performed because of avascular necrosis. Patients and methods To study cementless total hip replacement (THR) in younger patients with avascular necrosis (AVN), we analyzed retrospectively the outcome in 129 cases: 46 Mittelmeier monobloc ceramic hips (22 cases with AVN), and 83 Zweymuller total hip systems (35 cases with AVN) clinically and radiographically. Results At follow-up, 17 Mittelmeier prostheses (10 AVN) and 4 Zweymuller prostheses (none with AVN) had been revised. The diagnosis did not affect the implant survival, but the Zweymuller THR fared better than the Mittelmeier system. The main reason for revision of Mittelmeier implants was aseptic loosening, 3 of 4 Zweymuller revisions were necessary due to polyethylene wear. This difference was confirmed by the radiographic evaluation of the still intact implants: Zweymuller THR showed better values for signs of osseointegration, radiolucent lines around the implants and migration, but more acetabular wear. None of these differences was affected by the AVN diagnosis. Interpretation We could not confirm that AVN is a risk factor in total hip replacement.