Long-term outcomes of medial CMI implant versus partial medial meniscectomy in patients with concomitant ACL reconstruction

PURPOSE: To compare the clinical, objective and radiographic long-term results of patients with anterior cruciate ligament (ACL) lesion and partial medial meniscus defects, treated with ACL reconstruction and partial medial meniscectomy or medial CMI implant. METHODS: Seventeen patients treated with combined ACL reconstruction and medial CMI and 17 patients treated with ACL reconstruction and partial medial meniscectomy were evaluated with mean follow-up 9.6 years with Lysholm, Tegner, objective and subjective International Knee Documentation Committee scores, and VAS for pain. Arthrometric evaluation was performed with KT 2000. Weigh-bearing radiographs, antero-posterior and Rosenberg view, were also performed and evaluated with Kellgren-Lawrence score, Ahlback score and joint space narrowing. RESULTS: Pre-operative demographic parameters and clinical scores between patients treated with CMI and partial medial meniscectomy revealed no significant differences. A significant improvement of all the clinical scores was detected in both groups from pre-operative status to final follow-up. No significant difference between groups were found for clinical and radiographic scores; however, the chronic subgroup of patients treated with CMI showed a significantly lower level of post-operative knee pain compared to patients treated with partial medial meniscectomy and the acute subgroup of medial CMI showed better arthrometric scores. CONCLUSION: Good long-term clinical results in terms of stability, subjective outcomes and objective evaluation were reported both for medial CMI implant and partial medial meniscectomy, combined with ACL reconstruction for the treatment of partial medial meniscus tears combined with ACL lesions. Chronic meniscal tears treated with medial CMI reported lower levels of post-operative pain compared to meniscectomy, while acute lesions treated with medial CMI showed less knee laxity. Therefore, the use of the collagen meniscus implant in the case of anterior knee instability with a meniscal defect appears justified and able to improve clinical outcomes in the long term. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.