Evaluation of increased posterior tibial slope as a risk factor for anterior cruciate ligament injury

Abstract

Individuals who sustain anterior cruciate ligament (ACL) injury have an increased risk of developing early onset post traumatic osteoarthritis of the knee despite treatment received [1]. An increase in the posterior tibial slope is postulated to increase the risk of ACL rupture [2]. Measurement of the posterior tibial slope in individuals would serve as a means of screening and identifying those at increased risk of developing ACL injuries to take measures towards prevention. The aim was to measure and compare the mean value of the posterior tibial slope in adult patients with or without ACL injury. This was a hospital-based case-control study comprising 80 patients divided into two matched groups. Posterior tibial slope was measured on the plain lateral radiograph of the knee using the proximal tibial anatomic axis measurement protocol in all participants. Independent sample t-test was used to compare the means of the measured posterior tibial lope between cases and controls. The difference in the measured mean posterior tibial slope between the ACL injured group and the non-ACL injured group was found to be statistically significant with those in the ACL injured group having higher mean values (12.71 ± 1.2° vs 10.25 ± 1.1°) with a P value of < 0.001. Individuals with ACL injury have a significantly greater posterior tibial slope than those without ACL injury when measured on the lateral plain radiograph of the knee using the proximal tibial anatomic axis measurement protocol.