Ectopic bone formation in a child with a head injury: complete regression after immobilisation.

A girl aged 3 years was struck by an automobile and admitted to hospital unconscious with a head injury and a right hemiparesis. Pelvic and left femoral fractures were managed with skin traction. Three weeks after the injury the range of motion of the right hip joint was reduced and movements were painful. Radiographic examination two weeks later revealed heterotopic bone formation around the hip joint. Immobilisation was the only treatment offered. One year after injury, the ectopic ossification around the hip had resolved spontaneously, and she was able to walk independently.