Inferior shoulder dislocation

Background

Left shoulder and acromioclavicular joints with ligaments.

Shoulder anatomy, anterior.

Shoulder anatomy, posterior.

• Also known as "Luxatio Erecta" due to the affected arm being held 'erect', in a fully-abducted position
• About 0.5% of shoulder dislocations
• Typically caused by hyperabduction
  • Levers the humeral neck against the acromion
  • Rarely caused by high-energy force applied to shoulder from above
• Frequently associated with significant soft tissue injury or fracture

Shoulder dislocation types

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

Clinical Features

• Mechanism: forceful hyper-abduction of arm
• Humerus fully abducted
  • Hand on or behind head
• Humeral head palpable in axilla or lateral chest wall

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

Inferior dislocation with fracture of the greater tuberosity. Note how the humerus is abducted.

• Plain film X-ray in at least 2 views

Management

• Closed reduction
  • Consider procedural sedation

Single-Step Technique

1. Place sheet over upper shoulder and chest wall
2. Have assistant grasp sheet and provide countertraction
3. Grasp arm and apply traction upward and outward (along humeral axis)
4. Place arm in shoulder immobilizer
5. Obtain post-reduction radiographs

Two-Step Technique

• Converts inferior dislocation to anterior dislocation to allow reduction

1. Place one hand on the lateral mid-shaft of the humerus
2. Place second hand on medial epicondyle of elbow
3. Use first hand to apply pressure to the mid-shaft of the humerus while the second hand pulls the elbow cephalad
4. Perform reduction of the anterior shoulder dislocation
5. Place arm in shoulder immobilizer
6. Obtain post-reduction radiographs

• Failure of closed reduction may occur secondary to "buttonholing" of humeral through defect in glenohumeral capsule → consult ortho for open reduction

Contraindications to closed reduction

• Humeral neck or shaft fracture
• Suspected major vascular injury
• In these cases, open reduction is indicated

Disposition

• Discharge after successful reduction
• Outpatient orthopedic surgery follow-up

Complications

• Axillary nerve palsy in 60% (usually rapidly resolves after reduction
• Humerus fracture in 37%
• Rotator cuff tear in 12%

See Also

• Shoulder dislocation

External Links

Videos

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