Magnetic resonance imaging of chondral and osteochondral injuries.

Magnetic resonance (MR) imaging of the joints with routine pulse sequences can show the three main categories of osteochondral and chondral injuries: osteochondral fractures, osteochondritis dissecans, and chondral fractures. Detecting acute osteochondral fractures, which frequently accompany ligament tears, may modify patient treatment and ultimately may prove important in long-term prognostication. Staging osteochondritis dissecans lesions is possible with MR imaging and can be used to guide therapy, both surgical and nonsurgical. Specific treatment for chondral fractures is evolving; preoperative diagnosis using MR imaging is advantageous because these lesions often are not initially suspected, they are radiographically occult, and they clinically mimic other internal derangements, for which therapy differs. The MR imaging finding that these traumatic lesions share is the frequent presence of an abnormality in the subchondral bone. Fat-suppressed images are the key to detecting subtle areas of subchondral edema, which in turn may draw attention to a defect in the overlying articular surface.