Posterior shoulder dislocation: Difference between revisions

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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>
[[File:Gray326.png|thumb|Left shoulder and acromioclavicular joints with ligaments.]]
*MOI - forceful internal rotation/adduction (2/2 e.g. seizure, electric shock) or blow to ant shoulder
[[File:Shoulder_joint_back-en.png|thumb|Shoulder anatomy, anterior.]]
*Neurovascular and rotator cuff tears are less common than in ant dislocations
[[File:Shoulder joint back 05r4v.png|thumb|Shoulder anatomy, posterior.]]
*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>
*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
 
{{Shoulder dislocation types}}


==Clinical Features==
==Clinical Features==
*Prominence of posterior shoulder and ant flattening of normal shoulder contour
*Posterior aspect of shoulder unusually prominent
*Pt unable to rotate or abduct affected arm
*Anterior aspect of shoulder appears flattened
*Inability to rotate or abduct affected arm
 
===Mechanism===
*Forceful internal rotation and adduction
**Usually due to seizure or electric shock
***Consider in [[alcohol withdrawal]], even without clear history of shoulder injury
*Blow to anterior shoulder


==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
*Consider CT for occult dislocations of evaluation of fractures
*Bedside [[ultrasound: Joint|ultrasound]] can be used to assess for both dislocation and successful reduction


==Management==
==Management==
*Reduce
===Closed reduction===
**Consider [[procedural sedation]]
''Most require [[procedural sedation]]''
**Traction applied to adducted arm in long axis of humerus
#Adduct the arm
**Assistant pushes humeral head anteriorly into glenoid fossa
#Apply traction along long axis of humerus
*Post-reduction X-ray
#Have assistant push humeral head anteriorly into glenoid fossa
*Apply sling
#Apply shoulder immobilizer
[[[[File:posterior dislocation and luxatio erecta.jpg|thumbnail]]File:Posterior dislocation and luxatio erecta|thumbnail|Posterior Dislocation Reduction, www.clinicalgate.com]]
#Obtain post-reduction radiographs
 
===Indications for Surgery===
*Lesser tuberosity displacement not reduced with reduction
*Articular defect >25%
*Dislocation >3 weeks
**Do not reduce chronic dislocations in the ED due to risk of arterial injury; consult ortho for open reduction


==Disposition==
==Disposition==
*Discharge after reduction
*Discharge after successful reduction
*Ortho follow-up
**Maintain [[sling +/- swath]] or shoulder immobilizer (shoulder in adduction and internal rotation) until seen in follow-up by orthopedic surgery
*Any patient with a chronic dislocation requires orthopedic consult in the ED for consideration of operative reduction due to the risk of arterial injury
 
==Complications==
*[[Humerus fracture]] plus fracture of the posterior glenoid rim
*Isolate fracture of lesser tuberosity
*Reverse Hill-Sachs deformity
**Impaction fracture of anteromedial humeral head


==See Also==
==See Also==
*[[Shoulder dislocation]]
*[[Shoulder dislocation]]
==External Links==
*https://youtu.be/KRCqVekNEKc


==References==
==References==
<references/>
<references/>


[[Category:Ortho]]
[[Category:Orthopedics]]
[[Category:Procedures]]
[[Category:Procedures]]

Revision as of 20:27, 22 June 2020

Background

Left shoulder and acromioclavicular joints with ligaments.
Shoulder anatomy, anterior.
Shoulder anatomy, posterior.
  • 2-4% of shoulder dislocations[1]
  • 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

Shoulder dislocation types

Clinical Features

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

Mechanism

  • Forceful internal rotation and adduction
    • Usually due to seizure or electric shock
  • Blow to anterior shoulder

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
  • Consider CT for occult dislocations of evaluation of fractures
  • Bedside ultrasound can be used to assess for both dislocation and successful reduction

Management

Closed reduction

Most require procedural sedation

  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

Indications for Surgery

  • Lesser tuberosity displacement not reduced with reduction
  • Articular defect >25%
  • Dislocation >3 weeks
    • Do not reduce chronic dislocations in the ED due to risk of arterial injury; consult ortho for open reduction

Disposition

  • Discharge after successful reduction
    • Maintain sling +/- swath or shoulder immobilizer (shoulder in adduction and internal rotation) until seen in follow-up by orthopedic surgery
  • Any patient with a chronic dislocation requires orthopedic consult in the ED for consideration of operative reduction due to the risk of arterial injury

Complications

  • Humerus fracture plus fracture of the posterior glenoid rim
  • Isolate fracture of lesser tuberosity
  • Reverse Hill-Sachs deformity
    • Impaction fracture of anteromedial humeral head

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.