Hydroxyapatite Femoral Stems for Total Hip Arthroplasty

Abstract

Three hundred eighty hydroxyapatite-coated titanium alloy stems were implanted in a young and active patient population from 1987 through 1990. Within the population, 274 patients (314 hips) had a minimum 10-year and maximum 13-year followup. The average age of the population was 51 years. Thirty-seven percent of the population was 50 years or younger when operated on (average age, 39 years). Osteoarthritis was seen in 63.7% and avascular necrosis in 16.6% of patients. Fifty-four percent of patients were men. Clinically, these patients had early pain relief and rapid restoration of function. The Harris hip score averaged 92 points, and only 1.6% of patients had mild or moderate activity-related thigh pain. Radiographically, progressive remodeling occurred around the implants, 100% were bone stable, and no patient had endosteal distal osteolysis. Two patients had revision surgery for aseptic loosening: one at 2 years postoperative because of a nonunion of a concomitant subtrochanteric osteotomy and one at 9.5 years postoperative because of polyethylene wear and progressive osteolysis. The mechanical failure rate was 0.5%. The results show excellent lasting fixation of this tapered titanium alloy stem coated proximally with a thin, dense layer of hydroxyapatite. The stem has performed well in a young, active, high-risk population and in the hands of various surgeons.