Difference between revisions of "Posterior shoulder dislocation"

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==Background==
 
==Background==
*Accounts for 2-4% of shoulder dislocations<ref>Grate I Jr. Luxatio erecta: a rarely seen, but often missed shoulder dislocation. Am J Emerg Med. 2000 May;18(3):317-21.</ref>
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*2-4% of shoulder dislocations<ref>Grate I Jr. Luxatio erecta: a rarely seen, but often missed shoulder dislocation. Am J Emerg Med. 2000 May;18(3):317-21.</ref>
*Mechanism of injury - forceful internal rotation/adduction (secondary to e.g. seizure, electric shock) or blow to ant shoulder
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*Causes:
*Neurovascular and rotator cuff tears are less common than in ant dislocations
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**Forceful internal rotation and adduction  
 +
***Usually due to seizure or electric shock
 +
****Consider in alcohol withdrawal, even without clear history of shoulder
 +
**Blow to anterior shoulder
 +
*Complications (neurovascular injuries and rotator cuff tears) less common than in anterior dislocation
 +
*May go undetected for extended period as often missed on physical exam and imaging
  
 
==Clinical Features==
 
==Clinical Features==
*Prominence of posterior shoulder and ant flattening of normal shoulder contour
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*Posterior aspect of shoulder unusually prominent
*Patient unable to rotate or abduct affected arm
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*Anterior aspect of shoulder appears flattened
 +
*Inability to rotate or abduct affected arm
  
 
==Differential Diagnosis==
 
==Differential Diagnosis==
 
{{Shoulder DDX}}
 
{{Shoulder DDX}}
  
==Diagnosis==
+
==Evaluation==
 +
[[File:Lightbulb sign - posterior shoulder dislocation - Roe vor und nach Reposition 001.jpg|thumb|Light bulb sign (left) with post-reduction comparison (right)]]
 
*Plain film X-ray
 
*Plain film X-ray
 
**Scapular "Y" view shows humeral head in posterior position
 
**Scapular "Y" view shows humeral head in posterior position
 
**Lack of normal overlap of humeral head and glenoid fossa
 
**Lack of normal overlap of humeral head and glenoid fossa
 
**"Light bulb sign" - fixed internal rotation makes for light bulb appearance of humeral head on AP
 
**"Light bulb sign" - fixed internal rotation makes for light bulb appearance of humeral head on AP
 +
*Bedside ultrasound can be used to assess for both dislocation and successful reduction
  
 
==Management==
 
==Management==
*Reduce
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*Closed reduction
**Consider [[procedural sedation]]
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**Most require [[procedural sedation]]
**Traction applied to adducted arm in long axis of humerus
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#Adduct the arm
**Assistant pushes humeral head anteriorly into glenoid fossa
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#Apply traction along long axis of humerus
*Post-reduction X-ray
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#Have assistant push humeral head anteriorly into glenoid fossa
*Apply sling
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#Apply shoulder immobilizer
 +
#Obtain post-reduction radiographs
 +
*'''Note: Do not reduce chronic dislocations (>4 weeks) in the ED due to risk of arterial injury''' - consult ortho for open reduction
  
 
==Disposition==
 
==Disposition==
*Discharge after reduction
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*Discharge after successful reduction
*Ortho follow-up
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*Orthopedic surgery outpatient follow-up
 +
*Any patient with a chronic dislocation requires orthopedic consult in the ED for consideration of operative reduction due to the risk of arterial injury
  
 
==See Also==
 
==See Also==
 
*[[Shoulder dislocation]]
 
*[[Shoulder dislocation]]
 +
 +
==External Links==
 +
*https://youtu.be/KRCqVekNEKc
  
 
==References==
 
==References==

Revision as of 19:38, 26 September 2019

Background

  • 2-4% of shoulder dislocations[1]
  • Causes:
    • Forceful internal rotation and adduction
      • Usually due to seizure or electric shock
        • Consider in alcohol withdrawal, even without clear history of shoulder
    • Blow to anterior shoulder
  • Complications (neurovascular injuries and rotator cuff tears) less common than in anterior dislocation
  • May go undetected for extended period as often missed on physical exam and imaging

Clinical Features

  • Posterior aspect of shoulder unusually prominent
  • Anterior aspect of shoulder appears flattened
  • Inability to rotate or abduct affected arm

Differential Diagnosis

Shoulder and Upper Arm Diagnoses

Traumatic/Acute:

Nontraumatic/Chronic:

Refered pain & non-orthopedic causes:

Evaluation

Light bulb sign (left) with post-reduction comparison (right)
  • Plain film X-ray
    • Scapular "Y" view shows humeral head in posterior position
    • Lack of normal overlap of humeral head and glenoid fossa
    • "Light bulb sign" - fixed internal rotation makes for light bulb appearance of humeral head on AP
  • Bedside ultrasound can be used to assess for both dislocation and successful reduction

Management

  1. Adduct the arm
  2. Apply traction along long axis of humerus
  3. Have assistant push humeral head anteriorly into glenoid fossa
  4. Apply shoulder immobilizer
  5. Obtain post-reduction radiographs
  • Note: Do not reduce chronic dislocations (>4 weeks) in the ED due to risk of arterial injury - consult ortho for open reduction

Disposition

  • Discharge after successful reduction
  • Orthopedic surgery outpatient follow-up
  • Any patient with a chronic dislocation requires orthopedic consult in the ED for consideration of operative reduction due to the risk of arterial injury

See Also

External Links

References

  1. Grate I Jr. Luxatio erecta: a rarely seen, but often missed shoulder dislocation. Am J Emerg Med. 2000 May;18(3):317-21.