Acromioclavicular joint (AP view)

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The acromioclavicular AP view is a single projection assessing the patency of the acromioclavicular joint.

See also, acromioclavicular joint injuries.

Indications

The AP view of the acromioclavicular joint is often requested when the referrer either knows about or highly suspects an acromioclavicular joint injury. This projection is quite specific and will not include the shoulder girdle or the entirety of the clavicle.

Patient position

  • patient is erect
  • midcoronal plane of the patient is parallel to the image receptor, in other words, the patient's back is against the image receptor
  • acromioclavicular joint of the affected side is at the center of the image receptor
  • affected arm is in a neutral position by the patient side

Technical factors

  • anteroposterior projection
  • centering point
    • at the acromioclavicular joint
  • collimation
    • superior to the skin margins
    • inferior to the humeral head
    • lateral to include the skin margin
    • medial to lateral third of the clavicle
  • orientation  
    • landscape
  • detector size
    • 18 cm x 24 cm
  • exposure
    • 60-70 kVp
    • 10-15 mAs
  • SID
    • 100 cm
  • grid
    • yes (this can vary departmentally)

Image technical evaluation

  • the acromioclavicular joint is central to the image with no overlap

Practical points

It is not uncommon for additional projections to be requested, most commonly a bilateral view. Contrary to popular belief that the divergence beam will obscure the critical anatomy, one must take into account that the 'amount' of divergence for each joint will be equal.

Imaging in practice