Imaging description

AP and lateral elbow radiographs (Fig. 96.1) of an 11-year-old girl with elbow pain demonstrated a small subarticular lucency in the lateral capitellum with surrounding sclerosis and subtle flattening of the capitellum. Based on these imaging findings a diagnosis of osteochondritis dissecans (OCD) of the capitellum was made.

Radiographs are the most common initial modality for screening patients with suspected OCD. In the elbow, supplemental views such as 45 degrees flexion or oblique views may help to demonstrate the lesion. Elbow radiographs may be normal in the early stages of OCD of the capitellum. With disease progression, flattening of the capitellum is noted with focal rarefaction and non-displaced subchondral fragmentation. In late stages, a focal defect of the articular surface may be noted, with presence of a loose body.

A radiographic classification of OCD has been described based on AP radiographs. A grade I lesion demonstrates cystic change in the lateral or middle capitellum, a grade II lesion shows a gap between the lesion and the underlying subchondral bone, and a grade III lesion is characterized by the presence of a loose body.