Comparison of clinical outcomes between total knee arthroplasty and unicompartmental knee arthroplasty for osteoarthritis of the knee: a retrospective analysis of preoperative and postoperative results

Background: Excellent results have recently been reported for both total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA), but there have been few reports about which has a better long-term outcome. The preoperative and postoperative results of TKA and UKA for osteoarthritis of the knee were thus compared. Methods: The results of 48 patients who underwent TKA and 25 patients who underwent UKA were evaluated based on clinical scores and survivorship in the middle long-term period. Preoperative, latest postoperative, and changes in the femoro-tibial angle (FTA), range of motion (ROM), Japanese Orthopedic Association score (JOA score), and Japanese Knee Osteoarthritis Measure (JKOM) were compared. The patients' mean age was 73 years. The mean follow-up period was 9 years (TKA: mean, 10.5 years; range, 7-12 years; UKA: mean, 9 years; range, 6-11 years). Results: Preoperative FTA and ROM were significantly higher in the UKA group than in the TKA group. Total changes in all scores were similar among the two groups, as were changes in scores for all JOA and JKOM domains. The cumulative revision rate was higher for UKA than for TKA (7 versus 4 %). Kaplan-Meier survivorship at 10 years was 84 % for UKA and 92 % for TKA. Conclusions: This clinical study found no significant differences between TKA and UKA, except in long-term survivorship.