Stress fracture of the ulna in an adolescent baton twirler.

Upper extremity stress fractures are rare, with the majority of those reported occurring in the ulna. The location of the fracture is influenced by the type of activity and mechanism of injury with which it is associated. We report the first case of a mid-ulnar stress fracture in a baton twirler due to chronic torsional stress. This patient was referred to our Orthopedic Oncology clinic with a preliminary diagnosis of osteoid osteoma.