[The role of the posterior tibial slope on rupture of the anterior cruciate ligament].

Background/aim: Posterior tibial slope is one of the most citated factors wich cause rupture of the anterior cruciate ligament (ACL). The aim of this study was to determine the association of a greather posterior tibial slope on the lateral condyle, that is a lesser posterior tibial slope on the medial condyle, with ACL rupture.

Methods: The patients were divided into two groups. The study group included the patients with chronic instability of the knee besause of a previous rupture of ACL. The control group included the patients with knee lesion, but without ACL rupture. Posterior tibial slope measuring was performed by sagittal MR slices supported by lateral radiograph of the knee. We measured posterior tibial slope on lateral and medial condyles of the tibia. Using these values we calculated an average posterior tibial slope as well as the difference between slopes on lateral and medial condyles.

Results: Patients with ACL rupture have highly statistically significantly greather posterior tibial slope (p < 0.01) on lateral tibial condyle (7.1 degrees : 4.5 degrees) as well as statistically significantly lesser posterior tibial slope (p < 0.05) on medial tibial condyle (5.9 degrees : 6.6 degrees) than patients with intact ACL.

Conclusion: Great posterior tibial slope on lateral tibial condyle associated with the small posterior tibial slope on the medial tibial condyle, that is a positive differentce between lateral and medial tibial condyles are factors wich may cause ACL rupture.