Increased tibial and meniscal slopes are risk factors for meniscal tears: A systematic review.
PURPOSE The influence of posterior tibial slope (PTS), meniscal slope (MS) and meniscal bone angle (MBA) on meniscal injury risk is poorly understood. This systematic review and meta-analysis aims to evaluate whether PTS, MS and MBA are significant risk factors for meniscal tears. METHODS A systematic search of PubMed, Embase and Scopus was conducted according to PRISMA guidelines. Eligible studies compared PTS, MS or MBA measurements between patients with meniscal injuries and controls with intact menisci. Study quality was assessed using the methodological index for non-randomised studies (MINORS). Data were synthesised using a random-effects model to calculate mean differences with 95% confidence intervals. Subgroup analyses were performed based on tear type, and meta-regression explored potential sources of heterogeneity, including concomitant ACL injury and measurement technique. RESULTS A total of 35 studies comprising 7122 knees were included. Increased medial PTS was significantly associated with medial meniscus tears (MD = 1.02°, 95% confidence interval [CI] [0.49; 1.55], p < 0.001), while increased lateral PTS was associated with lateral meniscus tears (MD = 1.11°, 95% CI [0.30; 1.91], p = 0.007). Increased medial MS was also significantly associated with ramp lesions (MD = 0.98°, 95% CI [0.24; 1.73], p < 0.001). Subgroup analyses demonstrated the strongest association between medial MS and medial meniscus posterior root tears. Substantial heterogeneity was present across analyses (I2 range = 68.9%-91.7%). Meta-regression analysis did not identify concomitant ACL injury as a significant moderator of the association between PTS and meniscal tears. CONCLUSION Increased medial PTS and lateral PTS are associated with higher risks of medial and lateral meniscus tears, respectively, with the strongest effects observed for medial posterior root tears. Elevated medial MS is also associated with ramp lesions. While these findings highlight anatomical risk factors that may contribute to meniscal injury risk, future prospective studies are needed to establish clinically meaningful thresholds and clarify the role of slope parameters within multifactorial risk models. LEVEL OF EVIDENCE Level IV, systematic review of level III-IV studies.