Total hip replacement with an entirely hydroxyapatite-coated prosthesis: 5 years' follow-up of 94 consecutive hips.

The first 100 consecutive entirely hydroxyapatite (HA)-coated hip arthroplasties in 86 patients (mean age, 56.2 years [range, 32-73 years]; female-to-male ratio, 75:25) were followed with standardized radiographs annually up to 5 years. All components developed 100% intimate bone-implant contact, being gradually reduced to 99.5%+/-3.8% by 2 partial periacetabular lines and on the femoral side to 94.0%+/-6.1% and 96.5%+/-5.2% in the frontal and lateral planes by lines along 75 stems, mostly in zones 1 and 8. Bone formation took place adjacent to the prostheses regularly, with gap filling and comprehensive periprosthetic bone remodeling, stabilizing at 3 years. No adverse stress shielding was found. The clinical results were excellent without thigh pain. We believe that all components were bonded directly to bone, promoted by the reliable primary fixation and the osteoconductive effect of HA.