Biceps tendon blocks reduction of isolated radial head dislocation.

A case of an unreducible radial head dislocation found in a 7-year-old girl illustrates the frequent delay in diagnosis associated with radial head dislocation. Her initial radiographs showed the radial neck access not passing through the center of the capitulum, which is diagnostic of radial head dislocation. She had no associated injuries to the elbow joint or neurovascular structures. Closed reduction was not stable, and open reduction revealed the biceps tendon displaced posteriorly and laterally from the radial tubercle around the radial neck, which prevented stable reduction of the anteromedial dislocation of the radial head. Once it was reduced through the radial capitular joint to its normal anatomy, the reduction was stable. Following a routine postoperative course, an excellent result was obtained.