Abstract
Introduction To assess five-year survivorship and clinical outcome following unicompartmental knee replacement (UKR) and total knee replacement (TKR) in pre-operatively matched patient groups.
Methods From a prospective database of over 600 patients undergoing knee replacement for osteoarthritis, 70 primary Oxford UKRs (62 patients) were matched pre-operatively with 70 primary PFC TKRs (68 patients) for age, sex, body mass index, knee range of movement and Knee Society Score (KSS). The two groups were assessed at six, eighteen, thirty-six and sixty months following knee replacement and compared for survivorship of the prosthesis (with failure defined as revision for any reason or ‘worst-case’ assuming all patients lost to follow up are revised), post-operative ROM achieved and clinical outcome based on the KSS (reported as separate knee and function score).
Results Three (5 percent) patients in the UKR group and two (3 percent) in the TKR group were unavailable for follow-up at five years. Five-year survivorship based on revision for any reason was 90 percent (95 percent Confidence Interval (CI): 82 to 98) for UKR and 100 percent (95 percent CI: 100 to 100) for TKR (log rank test: p=0.009). The ‘worst-case’ five-year survivorship (assuming all patients lost to follow up are revised) was 85 percent (95 percent CI: 76 to 94) for UKR and 97 percent (95 percent CI: 93 to 100) for TKR (log rank test: p=0.02). The mean post-operative ROM achieved was 105.3 degrees following UKR and 98.3 degrees following TKR (difference 7.0 (95 percent CI 3.3 to 10.6), p< 0.001). There was no difference in the KSS between the two groups for the knee score (difference 0.1 (95 percent CI: −4.3 to 4.5), p=0.9) and function score (difference 2.6 (95 percent CI: −1.7 to 6.9), p=0.2).
Conclusion In comparable patients with osteoarthritis of the knee, survivorship remains superior for TKR at five years. The ROM achieved is greater for UKR but there is no difference in the overall clinical outcome following UKR or TKR. We believe that UKR should only be performed in carefully selected cases because mid-term clinical outcome is similar following UKR or TKR and the complication rate may be higher for UKR.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
