Composite Tibial and Meniscal Angle Ratios from Both Compartments on MRI Are Associated With Anterior Cruciate Ligament Rupture
O.D. Meyer, J.T. Amaro, C.C. Kaleka, P.D. Vargas, N.G. Oliveira Filho, M. CohenObjectives:
To evaluate the association between tibial slope, meniscal slope, and meniscal-bone angle (MBA) in both medial and lateral compartments on MRI, and to determine whether composite indices derived from these measurements improve risk stratification for anterior cruciate ligament (ACL) rupture.
Methods:
This retrospective matched case-control study included 50 patients with confirmed ACL rupture and 50 age- and sex-matched controls. Tibial slope, meniscal slope, and MBA were measured on standardized sagittal MRI slices of each tibial plateau by two blinded musculoskeletal radiologists. Interobserver reliability was assessed using intraclass correlation coefficients (ICC). Group comparisons were performed using paired Student’s t-tests with effect size calculation. Composite ratios between tibial slope and MBA, as well as between tibial slope and meniscal slope, were analyzed separately for medial and lateral compartments.
Results:
Interobserver agreement was excellent for all measurements (ICC 0.847–0.965). ACL-ruptured knees demonstrated significantly greater tibial slope and more negative meniscal slope in both compartments compared with controls. The lateral meniscal-bone angle was significantly smaller in the ACL rupture group, whereas the medial MBA showed no isolated difference. Composite tibial slope/MBA ratios were significantly higher in ACL-ruptured knees in both medial and lateral compartments (p ≤ 0.002), whereas tibial slope/meniscal slope ratios were not discriminatory.
Conclusion:
Tibial slope, meniscal slope, and meniscal-bone angle on MRI differ between ACL-ruptured and control knees. Composite tibial slope/meniscal-bone angle indices demonstrated superior discriminatory ability compared with isolated measurements, supporting the value of combined morphological assessment of both knee compartments for identifying geometry associated with ACL rupture.