Bone Bruises Associated with Anterior Cruciate Ligament Injury as Indicators of Injury Mechanism: A Systematic Review

Background Anterior cruciate ligament (ACL) injury is one of the most common injuries in sports, and the injury mechanisms are not completely clear. Bone bruises seen on magnetic resonance imaging (MRI) following ACL injuries may provide significant information for determining ACL injury mechanisms. Objective The aim was to determine ACL injury mechanisms through an evaluation of locations of bone bruises associated with ACL injury. Methods A search for related articles in PubMed and the EBSCO Sport Database was performed using selected search strings from inception to August 6, 2018. Original studies with specified bone bruise locations identified using MRI technology were reviewed. Results A total of 12 studies with 589 patients were selected for review. A total of 471 bone bruises in the lateral tibial plateau were reported. Of these bone bruises, 409 (87%) occurred in the posterior section. A total of 242 bone bruises in the medial tibial plateau were reported. Of these bone bruises, 208 (86%) occurred in the posterior section. A total of 266 bone bruises in the lateral femoral condyle were reported. Of these bone bruises, 65 (25%) and 184 (69%) occurred in the anterior and central sections, respectively. A total of 105 bone bruises in the medial femoral condyle were reported. Of these bone bruises, 49 (47%) and 41 (39%) occurred in the anterior and central sections, respectively. Conclusions Bone bruise location patterns indicate that tibial anterior translation relative to the femur was a primary injury mechanism in the majority of ACL injuries selected in this review, and that the maximal knee valgus apparently occurred after tibial anterior translation sufficient to injure the ACL. Bone bruise location patterns also indicate knee hyper-extension as another mechanism of non-contact ACL injury.