Prospective Matched-Pair Analysis of Hydroxyapatite-Coated and Uncoated Femoral Stems in Total Hip Arthroplasty

This prospective study was performed to examine the results of total hip arthroplasty with a tapered uncemented femoral component with and without hydroxyapatite coating in a matched-pair group of patients. Since our original publication in 1996, no femoral component was revised in either group. After a mean clinical and radiographic follow-up of 9.8 years, all femoral components were stable, with no evidence of progressive radiolucency or osteolysis. Ten acetabular components were revised because of aseptic loosening and wear. Our study demonstrated no clinical or radiographic advantage, during the first decade after implantation, to the use of hydroxyapatite on this design of femoral component in primary total hip arthroplasty. Level of Evidence: Therapeutic study, Level II-1 (prospective cohort study). See Instructions to Authors for a complete description of levels of evidence. Background Summary of Results of Original Publication ifty-two pairs of patients treated consecutively with total hip arthroplasty by multiple surgeons at a single institution were retrospectively identified by matched-pair analysis and then studied prospectively. Half of the patients received a femoral component that was porous-coated proximally with hydroxyapatite (Taperloc; Biomet, Warsaw, Indiana), and the other half (the controls) received an identical component without hydroxyapatite. A 28-mm femoral head was used in all hips. Identical cementless plasma-sprayed but not hydroxyapatitecoated hemispherical acetabular implants (Universal cup; Biomet) were used in both groups. The patients were matched for age, sex, weight, diagnosis, Charnley class, operative approach, bone quality, femoral head size, type of acetabular component, and duration of follow-up. At the time of the original follow-up, at a mean of 2.2 years (range, two to 3.4 years) postoperatively, the mean scores according to the system of Merle d’Aubigné and Postel, as modified by Charnley, for pain, function, and motion were 5.6, 5.5, and 5.6 points, respectively, in the group that had received a hydroxyapatite-coated femoral component and 5.6, 5.6, and 5.6 points, respectively, in the group that had received a nonhydroxyapatite-coated component. None of these differences were significant. There had been no revisions in either group. Radiographs indicated stable fixation in both groups, and no differences in the radiographic parameters of loosening between the two groups were noted. The overall clinical results were excellent for both groups and, within the relatively short time frame of the original study, there appeared to be no clinical or radiographic advantage to the use of hydroxyapatite in this primary total hip arthroplasty. In the present study, we examined the results in the same cohort of patients after they had been followed clinically and radiographically for a mean of 9.8 years. Methods Demographic Data he present study included forty-three pairs of surviving patients. Nine pairs of patients from the original cohort were excluded because of the death of one of the members of the pair. All components were well fixed and functioning at the time of death. The demographic features of the forty-three pairs of surviving patients are shown in Table I. F