Ten-year follow-up of an anatomical hydroxyapatite-coated total hip prosthesis.

We report our results after ten year follow-up of 107 consecutive ABG-I hip prostheses implanted between June 1990 and December 1992: Only 84 prostheses were still in the study after ten years, but only six patients had undergone surgical revision. We can consider our clinical outcomes as excellent, with a whole-implant survival rate greater than 96%, a mean Merle D'Aubigne and Postel score increasing from 7.97 before operation to 16.17 at ten year follow-up, and a personal subjective assessment as excellent or good in 82.14% of patients. However, radiographic outcomes are more worrying: around 90% of patients show a stress-shielding phenomenon and granulomatous lesions in the proximal femur, and more than 82% suffer polyethylene wear greater than one millimetre (mean 1.68 mm). We think that zirconia stem heads and hooded antiluxation PE inserts are determining factors in the process of PE wear and, secondarily, in cancellous bone resorption and bone osteolysis.

Hydroxyapatite-coated hip prostheses. Early results from an international study.

A hydroxyapatite-coated hip prosthesis designed to stimulate proximal femoral stress transfer was studied in 222 patients undergoing primary total hip arthroplasty with a minimum followup of 2 years. The femoral component was a roughened titanium alloy with a 50-mu coating of hydroxyapatite applied to the proximal third. A proximal press-fit technique was applied with distal femoral over-reaming as standard procedure. The hydroxyapatite-coated acetabulum was of hemispherical design. Analysis of the clinical results showed a mean Merle D'Aubigné score of 16.7 points at 6 months and 17.4 points at 2 years. Mild residual thigh pain of unknown origin was reported in 3.6% of patients at 2 years. Radiographic evaluation showed complete acetabular and proximal femoral osseointegration without any loosening. No radiolucency or reactive line formation was observed around the hydroxyapatite-coated areas of the prostheses. Femoral bone densification occurred at the coated-uncoated transition zone (54%); 4% to 6% of cases showed cortical hypertrophy at the uncoated area of the stem. Reactive lines were seen around the distal stem in 52% of patients after 2 years. The clinical outcome was excellent, and the radiographic data pointed mainly to proximal femoral stress transfer.