Radiographic Appearance
Initially the capitulum appears irregular with areas of
radioluceny
(indicating resorption), particularly adjacent to the articular
surface, and sclerosis;
- in 3-5 months, radiographs show larger radiolucent areas followed
by
reconstruction of the bony epiphysis;
- in 1 to 2 years, the epiphysis returns to its normal configuration
w/
no flattening, presumably because the elbow is not wt bearing joint;
- in about 50% of pts, adjacent radial head shows early maturation
compared with the univolved elbow;
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Pathology
Clincially and radiographically, osteochondritis dissecans of the
elbow is very similar to Panner's disease. Though the exact etiology
of these osteochondroses of the humeral capitellum is not known,
theories include trauma, ischemia, and genetic causes (7). First
described in 1927 (8,9), Panner's disease is characterized by
disordered epiphyseal endochondral ossification, which may arise
spontaneously.
An identical appearance may arise as a complication of repetitive
stress such as that seen with throwing. In fact, there is
disagreement about whether osteochondritis dissecans of the humeral
capitellum and Panner's disease represent a spectrum of the same
pathologic condition or are different processes (1,10-12) though
current opinion favors the latter (7).
Panner's disease generally affects children under age 10, whereas
osteochondritis dissecans of the elbow affects preadolescents and
adolescents. Furthermore, Panner's disease involves the entire
epiphysis and is radiographically characterized by radiolucency and
fragmentation, similar to Legg-Calvé-Perthes disease of the hip.
Osteochondritis dissecans, on the other hand, typically affects the
lateral or central portion of the capitellum. The radiographic
appearance may include radiolucency of the capitellum, but it may
also include loose body formation and secondary changes of
hypertrophy of the radial head.
Panner's disease typically resolves with growth and development,
whereas osteochondritis dissecans may, and all too often does, lead
to degenerative arthritis.
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