Arthroscopic partial meniscectomy should be performed carefully for medial meniscus tear with the anteromedial meniscofemoral ligament

The clinical relevance of the anteromedial meniscofemoral ligament (AMMFL) in medial meniscus (MM) tears remains unclear. This study investigated whether arthroscopic partial meniscectomy (APM) for MM tears with AMMFL is associated with joint degeneration. Among 2568 patients who underwent arthroscopic surgery in 2003 to 2017, 10 with AMMFL and ≥2 years of magnetic resonance imaging follow-up were selected for this retrospective comparative study. Five underwent APM for MM tears (excluding subtotal meniscectomy), while the other 5 did not. Procedures involving the lateral meniscus were excluded from group classification. Pre- and postoperative cartilage statuses and subchondral bone marrow lesions were assessed based on magnetic resonance imaging Osteoarthritis Knee Score criteria. The sum of cartilage and bone marrow lesion scores of the medial femoral condyle and tibial plateau was compared between the groups. Clinical outcomes were evaluated using the Lysholm score. Over a mean 50.4-month follow-up (range, 28-88), statistically significant chondral wear was noted in both the femoral condyle and tibial plateau (P = .011 and P = .042, respectively). The 2 groups showed statistically significant differences in postoperative femoral and tibial cartilage statuses (P = .048 and P = .008, respectively) and tibial cartilage score change (P = .008). There were no inter-group differences in the Lysholm score. APM for MM tears with AMMFL may accelerate cartilage degeneration in the medial compartment. The AMMFL should not be resected indiscriminately, and efforts should be made to preserve it when possible. Considering the difference between MM with the AMMFL and typical MM, surgical intervention on the former should be performed more carefully. These findings should be interpreted with caution given the small sample size included in this study.