Tardy displacement of traumatic radial head dislocation in childhood.

The diagnosis of traumatic dislocation of the radial head, either isolated or as part of a Monteggia fracture-dislocation, was delayed in 10 of the 110 children treated with these injuries during the study period. In eight children, the dislocation was overlooked on the initial radiographs. In two children, the radial head was reduced on the initial elbow radiographs, but it was dislocated 10 days later in one child and 21 days later in the other. The most likely explanation is that the radial head dislocated at the time of impact, spontaneously reduced by the time the first radiographs were obtained, and redislocated while the arm was in a cast. We conclude that radiographic assessments of the radiocapitellar joint, by using the radiocapitellar line, are required in children with elbow and forearm injuries at presentation and when the cast is removed.