This systematic review investigates factors associated with outcomes after meniscal allograft transplantation (MAT). The PubMed, Scopus, and Cochrane Central Register databases were used to search relevant articles in April 2018. Studies that evaluated at least one association between a factor and outcomes were extracted. Of 3,381 titles, 52 studies were finally analyzed. Data about predictors, patient-reported outcome scores (PROMs), and failure rates were extracted for quantitative and qualitative analysis. A total of 3,382 patients and 3,460 transplants were identified. Thirty different predictors were reported in the current MAT literature, 18 of which by at least two studies. Subgroup analysis showed that lateral MAT had higher postoperative values than medial MAT in Lysholm's (p = 0.0102) and International Knee Documentation Committee (IKDC; p = 0.0056) scores. Soft tissue fixation showed higher postoperative IKDC scores than bone fixation (p = 0.0008). Fresh frozen allografts had higher Lysholm's scores (p < 0.0001) and showed significantly lower failure rates (p < 0.0001) than cryopreserved allografts. Age (p < 0.015, β = 0.80), sex (p < 0.034, β = - 8.52), and body mass index (BMI; p < 0.014, β = -4.87) demonstrated an association with PROMs in the regression model. Qualitative analysis found moderate evidence that a higher number of previous procedures in the same knee are an independent predictor of transplant failure. Conflicting evidence was found with regard to chondral damage, time from meniscectomy, smoke, sport level, worker's compensation status, and preoperative Lysholm's score as predictors of outcomes. Our review suggests that the ideal candidate to undergo MAT may be a young male of normal weight with no previous knee surgeries, treated with a lateral isolated procedure. However, MAT is associated with good outcomes in the majority of patients with many of the PROMs requiring further study to determine their direct effects on long-term outcomes. This study is a systematic review and reflects level of evidence IV.
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