The fully hydroxyapatite-coated total hip implant. Clinical and roentgenographic results.

The clinical and roentgenographic results of 54 fully hydroxyapatite (HA)-coated primary total hip arthroplasties in 45 patients was studied. Both the femoral and the acetabular components had a 200-microns coating of hydroxyapatite. The mean age of the patients was 54.8 years. Twenty-three patients were between 45 and 60 years of age. There were 24 men and 21 women. Nine patients under-went bilateral operations. The average follow-up period was 46.9 months (range, 24-78 months). The average preoperative Harris hip score was 48, and the average postoperative Harris hip score was 94 at 1 year and 96 at 2 years. Revision surgery for component loosening and infection was carried out in four (7.4%) cases. There was aseptic loosening of the femoral component in one case (1.85%) and of the acetabular component in two cases (3.7%). Roentgenographic evaluation indicated that greater stress transfer occurs in the distal two thirds of the femoral stem. Proximomedial femoral neck resorption was noted in 23 cases (57.4%). Excellent to good clinical outcome was obtained in 89% of patients. In the short term, the rate of aseptic loosening of the fully HA-coated hip prosthesis in our series is higher than the reported rates of aseptic loosening of proximally HA-coated total hip implants. Controlled clinical studies would be required to evaluate the relative efficacy of the fully HA-coated and the proximally HA-coated hip prostheses.