PURPOSE: To evaluate the association between tibial slope, meniscal slope and meniscal-bone angle (MBA), both medially and laterally, and to investigate whether composite indices derived from these measurements improve risk stratification for anterior cruciate ligament (ACL) rupture. METHODS: This is a retrospective matched case-control study including 50 ACL rupture cases and 50 age and sex-matched controls. Tibial slope, meniscal slope and MBA were measured on magnetic resonance imaging (MRI) by two musculoskeletal radiologists on standardized sagittal slices of each tibial plateau. Interobserver reliability was assessed using intraclass correlation coefficients (ICCs). Group comparisons were performed with paired Student's t tests, and effect sizes were calculated. Composite ratios between tibial slope and MBA, and between tibial slope and meniscal slope, were analyzed for both compartments. RESULTS: Interobserver agreement was excellent for all parameters (ICC = 0.847-0.965). ACL rupture patients had significantly greater lateral tibial slope (6.05° vs. 3.89°, p = 0.014), more negative lateral meniscal slope (-3.24° vs. 1.77°, p < 0.001) and smaller lateral MBA (22.91° vs. 27.35°, p < 0.001). Medially, tibial slope was higher (6.92° vs. 4.42°, p = 0.003) and meniscal slope lower (-3.68° vs. -1.02°, p = 0.001) in the ACL rupture group. The medial MBA showed no significant difference (p = 0.256). Composite indices of tibial slope/MBA ratio were significantly relevant in both compartments among ACL rupture patients (p ≤ 0.002). CONCLUSION: Tibial slope, meniscal slope and MBA on MRI significantly differed between ACL-ruptured and control knees. The composite tibial slope/MBA index provided higher discriminatory performance than isolated measures, supporting the use of combined morphological evaluation of both compartments for identifying knees with geometry associated with ACL rupture. LEVEL OF EVIDENCE: Level III, retrospective case-control study.
Meyer et al. (Tue,) studied this question.