Anterior Dislocation of the Shoulder

• Glenohumeral dislocation most common shoulder dislocation (85%)
• Glenohumeral joint dislocations make up >50% of all dislocations in the body
• Anterior / subcoracoid shoulder dislocation (96%)
• Mechanism
• External rotation and abduction and external rotation
• Age
• Younger individuals
• May be associated with
• Hill-Sachs defect (50%) is a depression fracture of posterolateral surface of humeral head from impaction of the head against glenoid rim in subglenoid type
• Best demonstrated on the AP projection with the arm internally rotated
• Bankart lesion is a fracture of anterior aspect of inferior glenoid rim
• Only cartilaginous portion of glenoid labrum may be fractured which may only be visible on MRI
• Fracture of greater tuberosity (15%)
• Complications
• Recurrent dislocations (40%)
• Post-traumatic arthritis
• Injury to axillary nerve or artery 

 
Anterior Dislocation of the Humeral Head: Top image shows humeral head displaced from glenoid and lying inferior to the coracoid process (red arrow); the middle image demonstrates a defect along the posterolateral aspect of the head, which is the Hill-Sach's deformity (green arrow). The lower image is the scapular Y view (blue line outlines scapula). The head lies in a subcoracoid (i.e. anterior location). The white arrows point to the acromion.