Zweymueller with metal-on-metal articulation: clinical,radiological and histological analysis of short-term results

BACKGROUND: This is a prospective study. METHOD:. A total of 266 consecutive patients, who received 350 third-generation Zweymueller-SL total hip arthroplasties with metal-on-metal articulation for primary or secondary osteoarthritis, was followed and evaluated clinically, radiologically and histologically. The age of the patients at the time of surgery was 55+/-9 years, (range 25-70 years). Seven ( 3%) patients did not return for their last follow-up evaluation for reasons unrelated to their hip operation. RESULTS: The mean follow-up was 52 months (range 37-92 months). The preoperative Harris hip score was 45+/-19 and increased to 96+/-4 postoperatively. The invalidity of the patients was significantly improved postoperatively ( p<0.001). In all, 97% of the patients were satisfied or very satisfied with the result of the operation. There was no aseptic loosening noted in this series. Revision was done in 6 (1.8%) hips because of septic loosening ( n=5, 1.5%) or technical error ( n=1, 0.3%) during implantation. Dislocation of the prosthesis occurred in the early postoperative period in 2 (0.6%) hips. Periarticular ossification was observed in 30% of the hips (5% Brooker grades III and IV), but without associated disability. During revision surgery, no macroscopic metalosis could be identified in the newly formed hip joint membrane; however microscopic evidence for metalosis (Mirra grades 1 and 2) was seen in all revised hips. The survival for Zweymueller screw socket and stem 7.6 years after implantation was 99.4% and 96.8%, respectively. CONCLUSIONS: This study showed that the short-term results of Zweymueller total hip arthroplasty with metal-on-metal articulation were just as satisfactory as those of a conventional polyethylene on ceramic articulation, while the metal-on-metal articulation does not seem to give rise to new problems or complications.