Evaluation of Intercondylar Notch and Tibial Slope Angles in Relation to Anterior Cruciate Ligament Injury: A Retrospective MRI Study in a Turkish Population

Abs tractAim: Intrinsic variations in knee anatomy, including the intercondylar notch and tibial slope morphology, are associated with anterior cruciate ligament (ACL) injury risk.This study aimed to evaluate the association between the intercondylar notch angle (INA), medial and lateral tibial slope angles MTSA and LTSA, and femoral notch width (FNW) and the occurrence of ACL rupture by comparing patients with ACL injury and healthy controls.Methods: This retrospective study included 413 individuals aged 20-40 years who underwent knee magnetic resonance imaging (MRI) between January 2016 and November 2019.The study group comprised 232 patients with complete ACL rupture, and 181 healthy individuals without ACL tears served as controls.Morphometric parameters, including the INA, MTSA and LTSA, FNW, intercondylar width (ICW), and notch width ratio (NWR), were measured and compared between groups.The NWR was calculated as FNW/ICW and classified as 0.27 or >0.27.Knees were also categorized by notch shape (A, U, W), and associations with age and sex were analyzed. Results:The mean INA and FNW were significantly lower, while the LTSA was significantly higher in the ACL rupture group than in controls (p<0.01).The NWR was also significantly lower in the ACL group (p<0.001).An NWR 0.27 was associated with a 2.24-fold increased risk of ACL rupture, with an area under the curve of 0.724, indicating moderate diagnostic accuracy.No significant difference in notch shape types (A, U, W) was observed between groups (p=0.169). Conclusion:Reduced notch dimensions, a lower NW ratio, and a steeper lateral tibial slope are significant anatomical risk factors for ACL rupture.Incorporating these MRI-based morphometric parameters into prevention programs may aid early identification of high-risk individuals.Prospective biomechanical studies are warranted to validate these findings and guide individualized prevention strategies.