Traumatic Shoulder Injuries: A Force Mechanism Analysis—Glenohumeral Dislocation and Instability

OBJECTIVE: Acute traumatic glenohumeral dislocation is one of the most commonly encountered shoulder injuries and can produce a complex combination of associated bony and soft-tissue injuries, the full extent of which is often initially underappreciated. The objectives of this article are to illustrate the relevant anatomy of the shoulder and provide a more intuitive understanding of the complex biomechanics of traumatic glenohumeral instability through the use of 3D modeling and animation to improve the radiologist's awareness of some of the most common injury patterns, and potentially improve the detection of associated injuries. Emphasis is placed on the most critical injuries to determine the ultimate treatment modality, and imaging recommendations are provided. CONCLUSION: Understanding the force mechanisms responsible for traumatic glenohumeral dislocation can potentially improve detection of associated secondary injuries, which can guide more effective injury classification and ultimately direct more appropriate and timely intervention.