Shoulder (external rotation view)

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The shoulder external rotation view is an additional projection to the standard shoulder series it is often combined with the internal rotation view to visualize the entirety of the humeral head.

Indications

This projection is often done as a series, it is useful to demonstrate the greater tubercle humerus in profile.

Patient position

  • patient is preferably erect
  • the midcoronal plane of the patient is parallel to the image receptor, in other words, the patient's back is against the image receptor
  • glenohumeral joint of the affected side is at the center of the image receptor
  • affected arm is externally rotated
  • the patient is slightly rotated 5-10°. Therefore, the body of the scapula is laying parallel with the image receptor
  • some departments may require further rotation to mimic that of 'true AP' projection

Technical factors

  • anteroposterior projection
  • centering point
    • 2.5 cm inferior to the coracoid process, or 2 cm inferior to the lateral clavicle at the level of the glenohumeral joint
  • collimation
    • superior to the skin margins
    • inferior to include one-third of the proximal humerus
    • lateral to include the skin margin
    • medial to include 2/3 of the clavicle
  • orientation  
    • landscape
  • detector size
    • 24 cm x 30 cm
  • exposure
    • 60-70 kVp
    • 10-18 mAs
  • SID
    • 100 cm
  • grid
    • yes (this can vary departmentally)

Image technical evaluation

  • 2/3 of the clavicle is visible
  • overlap of the humeral head with the glenoid
  • no foreshortening of the scapular body (as per the patient rotation discussed in the positioning)
  • the greater tubercle of the humerus is in profile

Practical points

The technical factors of this examination are not particularly demanding, and there is not much room for positioning error other than over or under rotation to compensate for the scapular body.

Patients will find it hard to externally rotate their arm, so take this into consideration and only have them perform is at the last minute.

An open glenohumeral joint is a sign of over rotation toward the affected side. This results in a more ‘glenoid AP’ view; some departments may ask the projection be done in the 'glenoid AP' view.