Unicompartmental or total knee arthroplasty? Results from a matched study

There are few direct comparative studies evaluating results after unicompartmental knee arthroplasty and total knee arthroplasty. We determined the active range of motion, Knee Society score, and 5-year survivorship rate after 54 consecutive unilateral unicompartmental knee arthroplasties compared with a matched group of 54 unilateral total knee arthroplasties. The two groups of patients were matched for age, gender, body mass index, preoperative active range of movement, and preoperative Knee Society scores. All patients had osteoarthritis of the knee. Patients were assessed prospectively at 6, 18, 36, and 60 months postoperatively, and the mean followup was 59 months in both groups. The mean postoperative active range of motion was greater after unicompartmental knee arthroplasty, but there were no differences in the overall Knee Society knee and function scores. The 5-year survivorship rate based on revision for any reason was 88% for unicompartmental knee arthroplasty and 100% for total knee arthroplasty. The worst case 5-year survivorship rate, assuming all patients lost to followup had revision surgery, was 85% for unicompartmental knee arthroplasty and 98% for total knee arthroplasty. Total knee arthroplasty was a more reliable procedure. Midterm clinical outcomes were similar for both procedures, but the complication rate may be greater for unicompartmental knee arthroplasty.