Articular cartilage injuries of the capitellum interposed in radial head fractures: a report of ten cases.

Ten cases of Mason type I and type II isolated radial head fractures are reported, in which an unexpected cartilaginous fragment of the capitellum trapped within the radial head fracture was identified at the time of surgery. In no case was this injury pattern identified on preoperative imaging, including computed tomography in 2 cases. Five patients did have preoperative mechanical findings with forearm rotation. At surgery, all capitellar fragments were found to originate from the posterolateral capitellum. Excision of the capitellar fragment and internal fixation of the radial head fracture were performed in all cases. No sequelae were identified on short-term follow-up. This series highlights an injury pattern that should be considered in isolated nondisplaced and minimally displaced fractures of the radial head. The natural history of this finding, when treated conservatively, is unknown.