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.
