Trauma X-ray - Upper limb
Glenohumeral joint

Key points

  • AP and Y-views are the standard views in the context of trauma
  • Anterior dislocation is much more common than posterior dislocation
  • Anterior dislocation results in the humeral head lying anterior to the glenoid and inferior to the coracoid process

Normal shoulder joint

The 'shoulder' joint is more accurately termed the glenohumeral joint.

In the context of trauma there are 2 standard views used to assess this joint. These are the - Anterior-Posterior (AP) view, and the lateral or 'Y-view'.

If the patient can tolerate holding the arm in abduction, an 'axial' view is an alternative to the Y-view.

Shoulder - Normal AP view

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Shoulder - Normal AP view

  • The humeral head and glenoid contours are aligned normally

Shoulder - Normal Y-view

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Shoulder - Normal Y-view

  • The Y-view is so named because of the Y shape of the scapula formed when looking at it laterally
  • The humeral head is correctly aligned - it overlies the glenoid and is positioned posterior to the coracoid

Shoulder joint - Normal axial view

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Shoulder joint - Normal axial view

  • The glenohumeral joint (GHJ) is aligned normally
  • The acromioclavicular joint (ACJ) is aligned normally

'Shoulder' dislocation

Shoulder dislocation is a term often used loosely to indicate dislocation of the head of the humerus from the glenoid of the scapula.

The shoulder can dislocate posteriorly, but anterior dislocation is approximately 50 times more common.

Anterior dislocations are usually associated with trauma with the arm abducted and in external rotation. Posterior dislocations are associated with electric shocks and epileptic seizures.

Anterior shoulder dislocation - AP view

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Anterior shoulder dislocation - AP view

  • Humeral head and glenoid surfaces are not aligned
  • The humeral head lies below the coracoid

Anterior shoulder dislocation - Y view

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Anterior shoulder dislocation - Y view

  • The humeral head lies anterior to the glenoid and inferior to the coracoid process

Anterior shoulder dislocation - Axial view

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Anterior shoulder dislocation - Axial view

  • The humeral head surface is no longer aligned with the glenoid
  • The humeral head lies anterior to the glenoid

Posterior shoulder dislocation - AP view

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Posterior shoulder dislocation - AP view

  • The glenohumeral joint is widened
  • Cortical irregularity of the humeral head indicates an impaction fracture
  • Following posterior dislocation the humerus is held in internal rotation and the contour of the humeral head is said to resemble a 'light bulb'
  • Note: Any X-ray acquired with the humerus held in internal rotation will mimic this appearance

Clinical information

  • Bilateral shoulder pain following epileptic fit

Diagnosis

  • Bilateral posterior shoulder dislocation (left not shown)

Posterior shoulder dislocation - Y view

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Posterior shoulder dislocation - Y view

  • The humeral head (blue line) no longer overlies the glenoid (red line)
  • The correct position of the humeral head is shown (green line)