Osteochondritis dissecans typically occurs in adolescent patients from repetitive high valgus stresses to the elbow, most commonly female gymnasts and male throwers. The repetitive valgus loads may create compressive forces across the lateral side of the elbow at the typical site of a pathologic process in the capitellum. It is thought that these forces cause repetitive micro-trauma and vascular insufficiency or injury to the capitellum that can lead to separation of the articular cartilage from the underlying subchondral bone. Genetic factors may also contribute in some cases. The condition occurs after the capitellum has almost completely ossified and involves both the articular cartilage and the underlying bone. If the articular cartilage becomes separated from the subchondral bone, it can become a loose body in the elbow joint.
Symptoms include activity-related lateral elbow pain that may improve with rest from the offending activity. The pain may be dull and poorly localized. Mechanical symptoms, such as clicking or locking, may be present if a loose fragment develops. On examination, tenderness to palpation is noted over the capitellum and a joint effusion may be present. Range of motion of the elbow may produce crepitus, and patients commonly lack the terminal 10 to 30 degrees of elbow extension. Limitation of elbow flexion or of forearm pronation and supination may also occur but is less common. Plain radiographs can show lucency or fragmentation at the capitellum and a possible loose body if a fragment has broken off. If findings on plain radiographs are equivocal, advancing imaging (CT or MRI) can confirm the diagnosis. MRI is preferred and can delineate a stable versus unstable lesion by showing intervening fluid between the fragment and subchondral bone.
For intact lesions without mechanical symptoms, treatment is initially nonoperative and includes rest and activity modification, with use of nonsteroidal anti-inflammatory agents as needed, followed by a graduated rehabilitation program and return to participation in the sport. Internal fixation of intact lesions may be performed either open or arthroscopically if nonoperative management fails. Displaced lesions or loose fragments typically require surgical excision of the fragment with drilling or microfracture of the capitellar defect. This can usually be done arthroscopically. Newer techniques of articular cartilage implantation are now being attempted in defects to try to restore normal articular cartilage, rather than the fibrocartilage produced by a microfracture technique.