Abstract :The residual rotatory instability after ACL reconstruction surgery is still a matter of concern among surgeons, although ACL reconstruction provides satisfactory clinical results. Different degrees of ACL tear combined with damage to other intra- and extra-articular structures of the knee result in different patho-laxities. In the last years, the anterolateral compartment of the knee and its ligamentous structures, like anterolateral ligament (ALL), have been advocated as one of the most important restrains for rotational instability. This kind of knee instability is well displayed with the pivot-shift test that correlates with patient’s clinical outcomes after ACL reconstruction. In this study we evaluated a population of 65 patients, who sustained ACL tears and underwent ACL reconstruction surgery. We revised their standard 1.5-T knee MRI before surgery and we tried to display the ALL structure and to highlight its tears.