Clavicle duplication following physeal injury.

Clavicle duplication is a rare entity with limited number of cases reported. Congenital origin and trauma related mechanisms are the main hypotheses to explain this anatomical variation. In skeletally immature patient, trauma may cause physeal-metaphyseal injury in the distal clavicle rather than acromioclavicular strain. The distal epiphysis remains in continuity with acromion and has an intact periosteal sleeve. The periosteal sleeve is extremely osteogenic, and may lead to new bone formation between epiphysis and displaced metaphysis. This remodeling potential and the intact acromioclavicular joint allow the children to be followed by closed reduction. However, there can be new bone formation between epiphysis and displaced metaphysis, resulting in clavicle duplication. Herein, we present the radiographic and computed tomography findings of a post-traumatic duplication of the clavicle in a 5-year-old boy.