"Dem bones": osteochondral injuries of the knee.

MR imaging plays a valuable role in the diagnosis and staging of osteochondral injuries of the femorotibial joint. Bone contusions may be the source of a patient's pain, and MR imaging characteristics of certain types may help to predict which contusions might progress to more serious osteochondral lesions. MR imaging also is vital in the diagnosis of occult osteochondral fractures and in accurately classifying displaced intra-articular fractures. Although osteochondral dissecans usually is diagnosed radiographically, MR imaging is the best noninvasive test for determining if an osteochondral fragment is unstable. Unstable lesions are a treatable cause of knee pain.