Musculoskeletal ImagingCapitulum, of humerus
1. Anatomya small spheroidal projection on the distal end of the humerus, which articulates with the radial head. Also, see capitulum of humerus.
2. Pathology
Fractures of this structure, which are rare, involve only the articular surface of the lateral condyle. Anteroposterior radiographs often appear normal, but lateral views reveal a semicircular radiopaque shadow where the capitulum is displaced. Type I (Hahn Steinthal type) are complete, whereas type II (Kocher Lorenz type) are partial. Usually these fractures result from a direct force applied through the radial head.
Osteochondritis of the capitulum is termed Panners disease (or sometimes "little leaguer's elbow"). This disorder is seen mainly in boys. Radiographically, the capitulum appears fissured, of increased density, small and fragmented (Fig.1). This appearance may make it difficult to differentiate from Osteochondritis dissecans of the elbow, but the latter usually occurs in older children after the ossification of the capitulum is completed, and in adults.
DR/RB
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AP radiograph of the elbow demonstrates fragmentation and increased density of the capitulum, due to Panner's disease.
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Capitulum, of humerus, Fig.1 | |