Pelvic lysis and polyethylene wear at 5-8 years in an uncemented total hip

The clinical and radiographic results of 160 primary, uncemented porous coated total hip replacements performed at 3 teaching hospitals were reviewed. Followup was obtained in 132 of 148 (89%) nondeceased patients. The acetabular component is a full hemisphere, fabricated of cobalt chrome with a sintered bead coating and was implanted with screws in all cases. A 32 mm cobalt chrome femoral head was used in all cases. At 2 to 4 years the incidence of pelvic lysis was 0 and no acetabular revisions had been performed. At 5 to 8 years followup, 3 of 132 (2%) femoral stems had been revised, while on the acetabulum side discrete expansile pelvic lytic lesions occurred in 15 cases (11%) with 8 cases (5%) requiring revision. Abrasion of the screwhead against the backside of the polyethylene liner was seen in all retrieved cases and may have contributed to the development of the lytic lesions seen. Use of this uncemented press fit hemispheric acetabular components, using adjunctive screw fixation resulted in an unacceptably high rate of polyethylene wear and aggressive pelvic lysis. While the results on the femoral side were good, the results with this uncemented acetabular system did not represent an improvement over previous cemented or uncemented acetabular components.