PATIENT OUTCOMES FOLLOWING UNICOMPARTMENTAL OR BICOMPARTMENTAL KNEE ARTHROPLASTY - A METAANALYSIS

The purpose of this study was to summarize the literature describing p atient outcomes following unicompartmental and bicompartmental knee ar throplasty. Original studies were included in this meta-analysis if th ey enrolled 10 or more patients at the time of an initial knee arthrop lasty and measured patient outcomes using a global knee rating scale. Forty-six studies on unicompartmental prostheses and 18 studies on bic ompartmental prostheses met these criteria. For unicompartmental studi es, the total number of enrolled patients was 2,391, with a mean enrol lment of 47 patients and a mean follow-up period of 4.6 years. The mea n patient age was 66 years; 67% were women, 75% had osteoarthritis, an d 16% underwent bilateral knee arthroplasty. The mean postoperative gl obal rating scale score was 80.9. The overall complication rate was 18 .5% and the revision rate was 9.2%. Studies published after 1987 repor ted better outcomes, but also tended to enroll older patients and pati ents with osteoarthritis and higher preoperative knee rating scores. F or bicompartmental studies, the total number of enrolled patients was 884, with a mean enrollment of 44 patients and a mean follow up period of 3.6 years. The mean patient age was 61 years; 79% were women, 31% had osteoarthritis, and 29% underwent a bilateral arthroplasty. The me an postoperative global rating scale score was 78.3. The overall compl ication rate was 30% and the revision rate was 7.2%. Although bicompar tmental studies reported lower mean postoperative global rating scale scores, these studies tended to enroll patients with worse preoperativ e knee rating scores. Recent improvements in patient outcomes followin g unicompartmental knee arthroplasty appear to be due, at least partia lly, to changes in patient selection criteria. Patient outcomes appear to be worse for bicompartmental arthroplasties than for other prosthe tic designs; however, patients enrolled in these studies had more poor ly functioning knees before surgery and actually had greater absolute improvements in global knee rating scores.