What is a Hill-Sachs Fracture?
A Hill-Sachs fracture is a compression fracture of the posterolateral humeral head that occurs when the humeral head impacts against the anterior glenoid rim during anterior shoulder dislocation. 1
Mechanism of Injury
- The lesion develops from impaction of the posterolateral margin of the humeral head against the anterior glenoid rim during shoulder subluxation or dislocation 2
- This creates an osseous defect (impression fracture) on the humeral head that can become "engaging"—meaning the defect catches on the anterior glenoid rim when the arm is abducted and externally rotated 3
- The defect progressively enlarges with each subsequent dislocation episode 3
Clinical Significance
- Hill-Sachs lesions are extremely common in anterior shoulder instability, with incidence approaching 100% in patients with recurrent anterior shoulder dislocations 4
- These lesions represent a bipolar injury pattern—they typically occur in conjunction with glenoid bone loss (such as bony Bankart lesions), and identifying both components is essential for optimal treatment outcomes 1, 4
- A "reverse Hill-Sachs lesion" (anteromedial humeral head compression fracture) occurs with posterior shoulder dislocations 1, 5
Diagnostic Imaging
- Standard radiographs (AP views in internal and external rotation plus axillary or scapula-Y view) can identify Hill-Sachs deformities associated with anterior dislocations 1
- CT scanning is superior to radiography for identifying and characterizing the reverse Hill-Sachs defect in posterior dislocations 1, 5
- MRI without contrast immediately after traumatic dislocation (when joint effusion provides natural distention) performs comparably to CT in evaluating humeral head bone loss 6
- MR arthrography is the gold standard in the subacute or chronic phase for comprehensive assessment of both the Hill-Sachs lesion and associated labroligamentous injuries 6
Clinical Impact
- Even a 25% Hill-Sachs defect increases in situ forces in the glenohumeral capsule and bony contact forces, which may have long-term implications for osteoarthritis development 7
- The presence of a Hill-Sachs defect may serve as a marker for significant concomitant injury to the anterior glenoid rim, emphasizing the importance of evaluating for associated pathology 7