Trunk rotation and hand-elbow-shoulder axis disruption increase the risk of humeral shaft fractures during arm wrestling: a video analysis study

BACKGROUND: Arm wrestling is a globally popular sport that can lead to serious orthopaedic injuries, particularly humeral shaft fractures. Despite their importance, the mechanisms and positional risk factors underlying these injuries have not yet been clearly defined. This study aimed to investigate whether specific body positions are associated with an increased risk of humeral shaft fractures. METHODS: This study was designed as a retrospective video-based observational comparative study. Seventy-four publicly available videos of arm wrestling matches resulting in humeral shaft fractures were independently evaluated by two orthopaedic specialists. In each video, the exact moment of fracture was identified, and the body positions of injured competitors were compared with those of their non-injured opponents. Variables including sex of competitors, side, match position (standing or sitting), time to fracture, and positions of the trunk, elbow, and wrist were recorded and statistically analyzed. RESULTS: A total of 148 competitors (74 with fractures and 74 non-injured opponents) were included in the analysis. Fractures occurred in the defense zone in 46 competitors (62.2%) and in the attack zone in 28 competitors (37.8%). Fracture occurrence was significantly associated with the angular zone of injury (p = 0.032). Fractures were more frequent among competitors who rotated their trunk toward the direction of attack (p < 0.001). Misalignment of the wrist, elbow, and shoulder and posterior positioning of the wrist relative to the shoulder were observed in 81.1% of competitors sustaining a fracture and were significantly associated with fracture occurrence (p < 0.001). CONCLUSIONS: The primary finding of this study was that trunk rotation, particularly toward the direction of attack, and disruption of the hand-elbow-shoulder axis were associated with fracture occurrence and may reflect increased torsional loading of the humerus. In addition, fractures were more frequently observed in defensive positions. These findings may help athletes participate in arm wrestling competitions more safely by increasing awareness of high-risk body positions.