What is a shoulder dislocation?

Shoulder dislocations happen when the bones in your shoulder joint are pushed or knocked out of their usual places.

A joint is any place in your body where two bones meet. They’re part of your skeletal system. Your shoulder joint is where the round ball at the top of your upper arm bone (humerus) fits into the socket (glenoid) of your shoulder blade (scapula).

A shoulder dislocation is an injury that happens when the ball and socket connection between your bones is separated. It can also damage the tissue around your shoulder joint, including your:

Types of dislocated shoulders

Healthcare providers classify dislocations depending on how far the bones in your joints were moved:

  • Complete dislocations (luxation): A complete dislocation happens when the bones in your joint are totally separated and pushed out of place.
  • Subluxation: A subluxation is the medical term for a partial dislocation. You have a subluxation if something pulls your joint apart and the bones still touch, just not as completely as usual.

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Anterior Dislocation (humeral head comes to lie anterior, medial and slightly inferior to its normal location and glenoid fossa).

Following an acute anterior glenohumeral dislocation:

  • Arm held in an abducted and ER position
  • Loss of normal contour of the deltoid and acromion prominent posteriorly and laterally
  • Humeral head palpable anteriorly
  • All movements limited and painful
  • Palpable fullness below the coracoid process and towards the axilla 
  • Possible damage to rotator cuff musculature and bone.
  • Vascular injuries may result from traction of the axillary blood vessels, resulting in a reduced pulse pressure or a transient coolness in the hands.
  • Peripheral nerve injuries are common due to traction if the brachial plexus.

PSD with-reverse-hill-sachs-and-reverse-bankart-lesions

Posterior Dislocation

With acute posterior glenohumeral dislocation:

  • Arm is abducted and IR
  • May or may not lose deltoid contour
  • May notice posterior prominence head of humerus
  • Tear of subscapularis muscle (weak or cannot internally rotate)
  • Neurovascular compromise is rare, but posterior shoulder instability may result from associated glenolabral and capsular injuries.

Posterior dislocations are hard to reduce, attempts at closed reduction need be performed in consultation with a treating orthopaedic surgeon. If the shoulder dislocation was ≥3 weeks ago (common in feeble elderly patients) or if their is reverse Hill-Sachs defect involving >20% of the articular surface, then the closed reduction is contraindicated.

 

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      J. Press
      Physiotherapist