Shoulder Dislocation



  • Shoulder is a very dynamic joint, prone to injury
  • Anterior dislocation (90–96%):
    • Injury is from direct or indirect forces on the abducted and externally rotated arm
    • Injury may also result from a direct blow to posterolateral aspect of shoulder
  • Posterior dislocation:
    • Often missed
    • Forces on the adducted and internally rotated arm result in posterior dislocation of humeral head in relation to glenoid fossa
    • Common mechanism is seizure and sudden contraction of all the posterior muscle groups
    • Other mechanisms include electrocution and direct blow to anterior shoulder
  • Inferior dislocation (rare):
    • Luxatio erecta
    • Hyperabduction of arm, tear of rotator cuff, and rotation of arm 180° above head; humeral head trapped underneath the coracoid and glenoid
    • Commonly seen after a fall from a height:
      • Arm has struck object on descent and is thrust above the head
    • Often accompanied by neurovascular injury and fracture

Pediatric Considerations
Dislocation is rare in children: Epiphyseal fractures must be suspected

Geriatric Considerations
Dislocation is often accompanied by fracture


  • Falls from height
  • Impact injuries
  • Distraction injuries of upper arm
  • Seizures
  • Electrocution

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