O3009 PREMATURE FAILURE OF PRIMARY TOTAL HIP ARTHROPLASTY WITH HYDROXYAPATITE-COATED ACETABULAR COMPONENT

Abstract

Aims: To evaluate the early midterm outcomes of primary total hip arthroplasty (THA) using Hydroxyapatite (HA)-coated on smooth surface acetabular component with 28 mm metal head on polyethylene liner articulation. Methods: Seventy primary THA in 63 patients with HA-coated acetabular component were performed consecutively between June 1993 and August 1996. Fifty-four cases were eligible for follow-up of average 71 months (48–104) and the mean age of index operation was 49 years (23–71). The clinical results were analyzed by modiþed Harris hip score, and the radiologic evaluation in terms of stability, polyethylene wear rate (Dorr method), osteolysis around acetabular component was done. Results: Mean Harris hip score improved from 50.9 to 82.2 at the last follow-up. Excellent or good results were found in 38 cases (70%). Eight cases (15%) were unstable radiologically. Pelvic osteolysis was found at 18 cases (33%). The mean polyethylene wear rate was 0.146 mm/year (0.01–0.45). Wear rate of hip dyaplasia was greater than osteonecrosis signiþcantly (p< 0.05). Seven cases (13%) were revised (5 mechanical failures, 2 deep infections). Any bone ongrowth was not found during revision surgery for loose components. Complications included 5 heterotrophic ossiþcations, 2 deep infections, and 1 nonrecurrent dislocation. Conclusion: Primary THA using HA-coated on smooth surface acetabular component showed unsatisfactory clinical results, accelerated polyethylene wear rate accompanying high incidence of osteolysis, and high loosening rate due to lack of bony ongrowth at early midterm.