Shoulder dislocation

Background

Left shoulder and acromioclavicular joints with ligaments.

Shoulder anatomy, anterior.

Shoulder anatomy, posterior.

• Humerus separates from the scapula at the glenohumeral joint
• Partial dislocation of the shoulder is referred to as subluxation
• Dislocation duration inversely correlated with likelihood of successful ED reduction

Shoulder dislocation types

• Anterior shoulder dislocation (~95%)
• Posterior shoulder dislocation (~5%)
• Inferior shoulder dislocation (<1%)

Clinical Features

• Shoulder pain
• Decreased shoulder range of motion

Comparison of Shoulder Dislocation Clinical Features

Finding	Anterior (~95%)	Posterior (~5%)	Inferior (<1%)
Arm position	Arm maintained in abduction and external rotation	Posterior aspect of shoulder unusually prominent	Humerus fully abducted / Hand on or behind head
Shoulder appearance	Loss of normal rounded appearance with stretching of the deltoid muscle (i.e., "squared off")	Anterior aspect of shoulder appears flattened
Range of motion	Difficulty touching affected arm to contralateral shoulder due to pain	Inability to rotate or abduct affected arm	Humeral head palpable in axilla or lateral chest wall
Mechanism	Most common; range of mechanisms	Forceful internal rotation and adduction (e.g., blow to anterior shoulder, seizure, eletric shock)	Forceful hyper-abduction of arm

Differential Diagnosis

Shoulder and Upper Arm Diagnoses

Traumatic/Acute:

• Shoulder Dislocation
  • Anterior shoulder dislocation
  • Posterior shoulder dislocation
  • Inferior shoulder dislocation
• Clavicle fracture
• Humerus fracture
• Scapula fracture
• Acromioclavicular joint injury
• Glenohumeral instability
• Rotator cuff tear
• Biceps tendon rupture
• Triceps tendon rupture
• Septic joint

Nontraumatic/Chronic:

• Rotator cuff tear
• Impingement syndrome
• Calcific tendinitis
• Adhesive capsulitis
• Biceps tendinitis
• Subacromial bursitis
• Cervical radiculopathy

Refered pain & non-orthopedic causes:

• Referred pain from
  • Neck
  • Diaphragm (e.g. gallbladder disease)
• Brachial plexus injury
  • Rucksack paralysis
• Axillary artery thrombosis
• Thoracic outlet syndrome
• Subclavian steal syndrome
• Pancoast tumor
• Myocardial infarction
• Pneumonia
• Pulmonary embolism

Evaluation

Workup

• Plain film X-ray
  • Include anteroposterior, scapular Y, and axillary views
  • Associated fractures include:
    • Hills-Sachs: cortical depression in the humeral head
    • Bankart: glenoid labrum disruption with bony avulsion
    • Humeral greater tuberosity fracture
• Consider joint ultrasound

Diagnosis

• 

  Anterior shoulder dislocation

• 

  Anterior shoulder dislocation on Y-view

• 

  Anterior shoulder dislocation with fracture

• 

  Inferior shoulder dislocation

• 

  Posterior shoulder dislocation

Management

Reduction

• Do not attempt to reduce chronic dislocations (>4 weeks) in ED due to risk of arterial injury - these require reduction in the OR
• Lower complications, equal pain control, and shorter ED stay with intra-articular lidocaine vs. procedural sedation
  • 20 mL of 1% lidocaine intra-articular injection
• See individual types for specific techniques:
  • Anterior shoulder dislocation
  • Posterior shoulder dislocation
  • Inferior shoulder dislocation

Post-Reduction

• Post-reduction film to confirm
• Sling and swathe or shoulder immobilizer x1 week / until orthopedics follow-up
  • Encourage daily range of motion exercises (minus abduction + external rotation) to prevent adhesive capsulitis

Disposition

• Uncomplicated dislocation can be discharged after reduction

Prognosis

• Recurrence rate around 27% if older than 30 years and 72% if younger than 23 years

See Also

• Shoulder diagnoses

External Links

• Good all-round shoulder reduction technique lecture
• Keeping Up in EM Shoulder Reduction Video
• Merk Manual - Shoulder dislocations