The Influence of Postoperative Tibiofemoral Alignment on the Clinical Results of Unicompartmental Knee Arthroplasty

PURPOSE: To evaluate the influence of postoperative tibiofemoral alignment on the clinical results and failure in patients who underwent unicompartmental knee athroplasty (UKA). MATERIALS AND METHODS: We reviewed 246 cases of medial UKA which were followed up for at least 5 years after the operation. The clinical results were compared between 5 groups classified according to the tibiofemoral angle that was measured at 3 months after surgery. We analyzed the relationship between the tibiofemoral alignment and the failure after UKA. RESULTS: The preoperative tibiofemoral angle was changed from 0.4° of varus to 5.4° of valgus after surgery and the average correction angle was 5.8°. During the follow-up, which averaged 7 years and 5 months, the knee score and function score were improved significantly in all groups regardless of the tibiofemoral angle (p<0.01). There were no significant difference between the groups in the clinical results (p>0.05). However, there were significant differences in the cumulative survival rate of implants between the groups and the highest rate was found in the group with a tibiofemoral angle of 4° to 6° of valgus (p<0.01). CONCLUSIONS: The tibiofemoral angle after UKA had no significant influence on the midterm clinical scores, but there was a significant relationship between the postoperative tibiofemoral angle and failure rate of implant.