Surgically treated comminuted spiral fracture of humerus caused by arm wrestling

Editor’s note: For 2020, the Physician Assistants in Orthopaedic Surgery awarded four $5,000 scholarships to PA students with an interest in orthopedics.

Part of the eligibility requirement for the scholarship is to author a publishable paper from either a research project or a case study. This year, we decided to also publish executive summaries of their work on Healio’s Physician Assistants in Orthopaedic Surgery blog. The summary of the first of the four winners comes after the following introduction.

This case study describes an interesting mechanism of a humerus diaphysis fracture, arm wrestling in a young male patient. Typically, humeral shaft fractures are treated nonoperatively, as many do well with conservative management. There is also an associated risk of radial nerve injury with open reduction with internal fixation (ORIF). Due to the extent of this patient’s fracture, however, the decision was made to stabilize it with a posterior plate and screws to allow early motion. The author suggests further research in the sport of arm wrestling to better understand the mechanisms and forces of arm-wrestling injury.

– Sam Dyer, PA-C, MHS

PAOS president

Comminuted spiral fracture

This case report describes a 25-year-old male patient without underlying bone disease who experienced a comminuted spiral fracture of the right humerus after arm wrestling his brother. Arm wrestling is typically viewed as a benign activity for healthy individuals and most fractures of the humerus occur from direct trauma and are treated conservatively with favorable outcomes. This report goes on to detail how if a humeral fracture is largely displaced, comminuted or severely angulated, then surgical intervention using plates and screws is employed to reduce the time to starting physical therapy and reclaiming loss range of motion.

While arm wrestling with his older brother, the patient experienced a sudden change in direction from winning the match to losing. The patient felt a sudden onset of pain and heard an audible crack in his arm. At the ED, right-sided humerus and elbow radiographs revealed a comminuted, displaced, spiral, distal humeral shaft fracture with butterfly fragment. Using a posterior triceps splitting approach, ORIF was accomplished using lag screws and neutralization plate without complication. This patient met all recovery landmarks and did not experience any radial nerve palsy, one of the most common adverse effects of humeral spiral fractures during his postsurgical therapy.

Peak stress

Humeral shaft fractures comprise approximately 3% of all fractures. Mostly, these are located in the middle third of the humerus 60% of the time and are caused by trauma or a direct blow to the arm. Typically, fractures caused by arm wrestling are located in the distal third of the humerus and do not appear to be correlated with isometric strength as these have been observed in children, female patients, the oldest patients, and in both dominant and non-dominant arms. The timing of these injuries has been observed to be primarily when a participant attempts to exert full force to overcome the external rotation vector induced by an opponent.

This case report also revisits a radiologic and biomechanical model which localizes the peak stress at 45° along a posteromedial longitudinal axis of the humerus. Given other emerging evidence of bony morphological adaptations due to explosive force displacement along the humeral midshaft observed in baseball pitchers, this paper concludes further research should be directed at attempting to observe if similar adaptations occur in arm wrestlers.

Arm wrestling is not a benign sport and the injuries can be complicated. Surgical fixation of spiral humeral fractures is a useful therapeutic plan to establish range of motion earlier. Future research efforts should begin to characterize the specific upper extremity bony adaptations competitive arm wrestlers undergo to better understand the mechanism of injury.