Midterm and Long-term Results of Medial Versus Lateral Meniscal Allograft Transplantation: A Meta-analysis

Background: It is unclear whether lateral meniscal allograft transplantation (MAT) procedures lead to better clinical outcomes than medial MAT. Hypothesis: The survival rates are similar between medial and lateral MAT, but the clinical outcomes of lateral MAT are better than those of medial MAT at final follow-up. Study Design: Meta-analysis. Methods: In this meta-analysis, we reviewed studies that assessed survival rates in patients who underwent medial or lateral MAT with more than 5 years of follow-up and that used assessments such as pain and Lysholm scores to compare postoperative scores on knee outcome scales. The survival time was considered as the time to conversion to knee arthroplasty and/or subtotal resection of the allograft. Results: A total of 9 studies (including 287 knees undergoing surgery using medial MAT and 407 with lateral MAT) met the inclusion criteria and were analyzed in detail. The proportion of knees in which midterm (5-10 years) survival rates (medial, 97/113; lateral, 108/121; odds ratio [OR] 0.71; 95% CI, 0.31-1.64; P =.42) and long-term (>10 years) survival rates (medial, 303/576; lateral, 456/805; OR 0.78; 95% CI, 0.52-1.17; P =.22) were evaluated did not differ significantly between medial and lateral MAT. In addition, both groups had substantial proportions of knees exhibiting midterm survivorship (85.8% for medial MAT and 89.2% for lateral MAT) but much lower proportions of knees exhibiting long-term survivorship (52.6% for medial MAT and 56.6% for lateral MAT). In contrast, overall pain score (medial, 65.6 points; lateral, 71.3 points; 95% CI, −3.95 to −0.87; P =.002) and Lysholm score (medial, 67.5 points; lateral, 72.0 points; 95% CI, −10.17 to −3.94; P <.00001) were significantly higher for lateral MAT compared with medial MAT. Conclusion: Meta-analysis indicated that 85.8% of medial and 89.2% of lateral meniscal allograft transplants survive at midterm (5-10 years) while 52.6% of medial and 56.6% of lateral meniscal allograft transplants survive long term (>10 years). Patients undergoing lateral meniscal allograft transplantation demonstrated greater pain relief and functional improvement than patients undergoing medial meniscal allograft transplantations.