Abstract
Introduction & Purpose of Study. The purpose of the present study was to evaluate the clinical, radiographic and histologic results with the Zweymueller total hip arthroplasty (THA) and metal-on-metal articulation. Material and Methods. Between 1994–2003, 380 patients received 415 third-generation Zweymueller-Plus THA with SL-stem and Bicon screw socket for hip osteoarthritis. Ten (5.15%) patients did not return for their last follow-up evaluation for reasons unrelated to their hip operation. This study reports on 217 THAs with follow up more than 60 months. The 217 THAs were implanted in 194 patients (143 women and 51 men), aged 55 ± 9 years, (25–70 years). The most common diagnosis for THA was primary osteoarthritis (48%) followed by secondary osteoarthritis due to developmental hip dysplasia (44%). Results. The follow-up was 77 ±17 months, (60 – 112 months). From the 217 THAs, 14 (6.4%) hips were revised for any reason; the socket in 5(2.3%) and the SL-stem in 9(4.1%) hips. The preoperative Harris hip score of 45±19 was improved to 96 ± 4 postoperatively. 95% of the patients were satisfied or very satisfied with the result of the operation. Revision was made in a total 14(4.6%) hips because of different reasons. The aseptic revision rate was 5%: 4(1.8%) Bicon cups and 7(3%) SL-stems were revised for aseptic loosening. The septic revision rate was 1.4% (3 THAs) and was due to Staph aureus. Periarticular ossification was observed in 32(17%) of the hips (5% Brooker grades III and IV), however without associated disability. The histological examination revealed mild metalosis (Mirra grades 1 and 2) in all revised hips. The cumulative survival for any reason (95% C.I.) was 90% (97% to 71%). The aseptic survival was 91% (97–72%) [95% CI); and specifically for the Bicon socket it was 98 % (100 to 92%); and for the SL-stem 93% (98% to 74%)[CI 95%]. The survival for the men and women was 78.9% and 94.4% respectively (log rank test: chi square P= 0.25). A significant, not statistically significant observation was that men showed lower survival for the stem than women (78.9 vs. 97.5%). Conclusion. This study showed that the medium-term results of Zweymueller total hip arthroplasty with metal-on-metal articulation were inferior particularly for the SL-stem to those obtained with the conventional Zweymueller total hip arthroplasty with polyethylene-ceramic articulation. This could be due either to allergic or mechanical (Sikomet Alloy) reasons.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
