Acromioclavicular joint (AP weight-bearing view)

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The acromioclavicular joint AP weight-bearing view, often performed together with the normal non-weight-bearing AP view, helps in ruling out joint displacement when it is suspected but not confirmed on the frontal image.

Indications

This view is used in the assessment of possible acromioclavicular joint separation and may be done bilaterally to allow comparison of joint spaces between the affected and unaffected side. Additionally, the bilateral weight-bearing view is able to unmask Rockwood Type V acromioclavicular joint injuries .

Note: Such functional views should not be performed on trauma patients without the strict instructions of a qualified clinician.

Patient position

  • the patient is erect holding a weight in the hand of the affected side
  • the patient's back is against the image receptor
  • the 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
  • the image is appropriately annotated weight-bearing

Practical points

This projection can be very painful for a patient with an AC joint injury; it is highly recommended that everything is set up and positioned so that the last thing you do is hand the weights over.