Abstract

This paper is a retrospective study between January 2007 - September 2012, and refers to a group of 1347 patients with acute or old  traumatic injury, with  instability of the knee (anteroposterior or combined) and  Magnetic Resonance Imaging (MRI) examination showed isolated or associated  lesions of  anterior cruciate ligament  (ACL). Out of 1347 patients  a group of 117 (8.6%) patients was selected, in whom MRI examination revealed associated lesions to the stability structures from the postero-lateral compartment. The paper is showing the spectrum of lesions identified by MRI in the  postero-lateral compartment and their correlation with the mechanism of injury  and the data from the clinical exam and the special tests for  the clinical assessment of rotational instability. The study will present statistics on identified  injuries and their MRI images. The highest incidence of lesions that have generated rotational instability  included the popliteal anatomical complex  formed by the popliteofibular ligament, postero-lateral capsule, arcuate ligament, fabelofibular  ligament, fibular collateral ligament, biceps femoris tendon and lateral gastrocnemius tendon. To be able to give fast and accurate diagnostic information to the surgeon, with therapeutic significance, to confirm or rule out the clinical diagnostic of   posterolateral rotational instability requires a good knowledge of the anatomy of the posterolateral compartment being known the vast anatomical variation  and the small dimension of these structures. Not being able to recognise and treat the  posterolateral compartment lesions contribute to ACL reconstruction failure due to significantly increased forces that will stress the graft with varus loading at various degrees of flexion.