KNEE ARTHROPLASTY IN RHEUMATOID-ARTHRITIS - A REPORT FROM THE SWEDISHKNEE ARTHROPLASTY REGISTER ON 4,381 PRIMARY OPERATIONS 1985-1995

The Swedish Knee Arthroplasty Register has data on 4,381 primary opera tions performed 1985-1995 for rheumatoid arthritis. Of these, 192 were performed with unicompartmental prostheses and 4143 with tricompartme ntal. 77% were women and the mean age was 66 years. There were 126 fir st, 20 second, and 1 third revision in tricompartmental arthroplasties , mainly for loosening, infection and patellar problems. There were 38 first, 3 second, and 1 third revision in unicompartmental arthroplast ies, mainly for progression of RA and loosening. Cumulative revision r ates (Kaplan-Meier) were calculated. Tricompartmental knees had a 10-y ear cumulative revision rate of 5% and uni-knees 25%. Patients treated before 1990, men and patients younger than 55 had higher revision rat es than patients treated after 1990, women and older patients, respect ively. Cemented tibial components resulted in lower revision rates tha n uncemented ones. There was no significant difference in revision rat es between patellar replaced and unreplaced knees or between the 9 com monest implant types.