MR imaging of anterior cruciate ligament tears

To investigate magnetic resonance (MR) imaging of anterior cruciate ligament (ACL) tears, the authors retrospectively reviewed 39 MR imaging examinations in 39 patients. We classified the MR imaging patterns of the torn ACL into four types. Torn ACL appears as a homogeneous iso-intensity mass on Type I images; as a continuous thin and waving low-intensity band with or without high-signal-intensity spots on the Type II images; as a disrupted band with a high-signal-intensity area on Type III images and as an absence of the ACL on Type IV images. We also report secondary lesions on MR imaging findings associated with tears of the ACL, posterior cruciate ligament index and bone bruising, in our patients. (author)