Imaging description

On radiography and CT, osteochondritis dissecans of the elbow is seen as a dome-shaped or somewhat circular-shaped lucency in the mid- or lateral aspect of the capitellum (Figure 27.1). However, in the advanced stage, it will be seen as a divot on the articular surface of the capitellum with a loose body/displaced fragment. The advanced stage of osteochondritis dissecans, will appear similarly on MRI. The earlier stages of osteochondritis dissecans without a loose body will appear as a dome-shaped, curvilinear lesion with a surrounding rim of low signal intensity on T1-weighted images with variable, heterogeneous signal intensity within the lesion. On T2-weighted images, lesions that are stable will also have a rim of low signal intensity and central heterogeneous, variable signal. However, when earlier lesions (those without fragment displacement) are unstable, they will have an intense rim of high signal on T2 or high signal cystic changes at the rim (Figure 27.2).

Importance

On MRI, it is important to identify stable lesions with an adjacent open distal humeral physis because these can be treated successfully with conservative therapy. The size of the lesion is also important as this can drive the type of surgical treatment (debridement with resection versus reconstruction of the injury – such as with osteochondral autograft transplantation surgery).