Impact of anterior cruciate ligament and medial collateral ligament injuries on medial unicompartmental knee arthroplasty outcomes.

OBJECTIVE

The objective of the study is to evaluate clinical outcomes of mobile-bearing Oxford phase III unicompartmental knee arthroplasty (UKA) for medial unicompartmental knee OA with/without anterior cruciate ligament (ACL) and/or medial collateral ligament (MCL) injuries and assess minimum clinically important differences (MCIDs).

METHOD: A total of 60 patients (70 knees) with anteromedial OA of the knee, treated between March 2020 and June 2022, were included in this retrospective study. Patients were divided into four groups a no ligament injury group (n = 15; 15 knees), ACL injury group (n = 18; 18 knees), MCL injury group (n = 12; 12 knees), and ACL + MCL injury group (n = 15; 25 knees). All surgeries were performed under general anesthesia using a medial parapatellar approach. The Oxford phase III unicompartmental knee prosthesis was implanted using bone cement. Post-operative rehabilitation included early mobilization, physical therapy, and pain management as part of an Enhanced Recovery After Surgery (ERAS) protocol. Pre-operative and post-operative data, including the Hospital for Special Surgery (HSS) scores and the American Knee Society Score (AKSS), were compared between the groups. Follow-up visits ranged from 15 to 36 months, with a mean of 28.3 months. The MCIDs for both the HSS and AKSS were also calculated and evaluated.

RESULTS

At the final follow-up, significant improvements in the HSS and AKSS scores were observed in all groups compared with pre-operative scores. The mean HSS score increased from 23.3 ± 5.2 preoperatively to 70.7 ± 8.2 postoperatively (p < 0.001), and the AKSS increased from 33 ± 5.35 preoperatively to 85.0 ± 5.35 postoperatively (p < 0.001). These results indicate significant improvements in knee function following UKA, regardless of ligament injury status.

CONCLUSIONS

Oxford phase III UKA demonstrates good short-term efficacy for medial OA with concomitant ligament injuries. Larger multicenter studies with extended follow-up are needed to validate long-term outcomes.