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 Zweymüller total hip systems (35 cases with AVN) clinically and radiographically.

RESULTS: At follow-up, 17 Mittelmeier prostheses (10 AVN) and 4 Zweymüller prostheses (none with AVN) had been revised. The diagnosis did not affect the implant survival, but the Zweymüller THR fared better than the Mittelmeier system. The main reason for revision of Mittelmeier implants was aseptic loosening, 3 of 4 Zweymüller revisions were necessary due to polyethylene wear. This difference was confirmed by the radiographic evaluation of the still intact implants: Zweymüller 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.