Shoulder dislocations

Background/Epidemiology

  • One of the most commonly dislocated joints.  Incidence ~12/100,000
    • Can be misdiagnosed/mismanaged
      • Important to manage appropriately to avoid complications (see below)
  • More common in young men (‘fighters’ 20-30 years) and older women (‘fallers’ 60-80 years)
  • Can be anterior, posterior or inferior
    • Anterior is the most common (95-98%)
      • Almost always associated with injury/trauma, usually when the shoulder is in abduction/hyperextension and external rotation
    • Posterior dislocation is unusual
      • Usually occurs with high-force trauma whilst the shoulder is held in internal rotation and adduction.  Occasionally occurs in states of convulsions/fits or electrical shock.

Risk factors

  • Contact sports
  • Older patients
  • Patients with previous shoulder dislocations
  • Disorders of collagen synthesis e.g. Ehlers Danlos

Presentation

  • History
    • Patient usually presents with a history of trauma with acute onset severe pain and inability to move the arm/shoulder
      • NB with recurrent dislocations, the trauma may be minimal and, occasionally, the patient may be able to relocate the joint themselves
    • Important to ask about the mechanism of injury
    • Ask about previous shoulder injury, dislocations or surgeries
  • Examination
    • In anterior dislocation
      • the arm is usually held in abduction and external rotation and patients will try to minimise any movements, particularly adduction and internal rotation
      • the normal contour of the deltoid may be lost
      • the humeral head may be palpated anteriorly
      • the acromion may be palpated posterolaterally
    • In posterior dislocation
      • the arm is usually held in adduction and internal rotation and abduction/external rotation are resisted (may be impossible to externally rotate to a neutral position); as is supination
      • a posterior bulge may be present and the humeral head may be palpable below the acromion process
      • may resemble frozen shoulder (especially in chronic unreduced dislocation)
    • there may be bruising/signs of injury
    • Neurovascular examination
      • Vascular
        • Check the radial and ulnar pulses
        • Examine for axillary haematoma
        • Measure capillary refill
        • Look for temperature and colour of the arm
      • Nervous
        • Axillary nerve damage
          • Badge patch sensation

Investigations

  • X-ray (usually 2 views, one of which AP, the other usually trans-scapular Y view or axillary view)
    • Posterior dislocations can be very difficult to differentiate from normal
    • In a normal AP view, the humeral head should be congruous with the glenoid.  In anterior dislocation, there is usually a loss of congruity
      • Sub-coracoid is the most common appearance for anterior dislocations
    • Axillary views are useful in evaluating the direction of dislocation

Management

  • Reduction
    • Before any reduction, appropriate analgesia should be given
    • There are two methods commonly used, both are equally as effective (use whichever the doctor finds most comfortable)
      • Hippocratic method
        • With the patient supine, hold the hand of the affected side and apply a slow, steady traction force to the extended arm whilst someone else provides resistance (or this can be done with your foot if you do not have assistance)

Fx_traction_countertraction_shoulder

      • Kocher method
        • The arm is placed in its anatomical position. Gently support the arm at the wrist and elbow before flexing the elbow to 90°. Then, externally rotate the arm until you encounter resistance. Apply a lateral distraction force to the humerus to unlock it from the glenoid, followed by internal rotation to return the arm to the resting position.
    • If reduction is unsuccessful, refer to orthopaedics (possibility of surgical reduction)
    • If reduction works, the shoulder should be immobilised in a sling for 4-6 weeks
      • An x-ray should be taken to confirm relocation

Complications

  • Soft tissue injury
    • Bankart lesion
    • Hill-sachs lesion
    • Rotator cuff tear
  • Neurovascular injury
    • Axillary nerve injury (10%)
    • Axillary artery rupture
  • Shoulder instability
    • Recurrent dislocations
    • Fractures (greater tuberosity, scapula, humeral head or shaft)

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