Elbow (AP view)

Last revised by Travis Fahrenhorst-Jones on 30 Jun 2022

The elbow AP view is part of the two view elbow series, examining the distal humerus, proximal radius and ulna. 

The projection demonstrates the elbow joint in its natural anatomical position allowing for adequate radiographic examination of the articulations of the elbow including the radiohumeral and humeroulnar joints.

This view is clinically indicated for trauma, chronic discomfort or infection of the elbow joint. It aids in visualizing fractures and/or dislocations of the elbow joint, in addition to osteomyelitis and arthritic changes. It is the preferred projection to assess the medial and lateral epicondyles of the humerus for avulsion-type fractures 2,3.

  • patient is seated alongside the table
  • the fully extended arm and forearm, in a supinated position, are kept in contact with the table by lowering the shoulder joint to the level of the table they all must be in the same plane as the detector (see Figure 1)
  • the detector is placed below the elbow joint
  • anteroposterior projection
  • centering point
    • mid elbow which is approximately the midpoint between the epicondyles 
  • collimation
    • superior to the distal third of the humerus
    • inferior to include one-third of the proximal radius and ulna
    • lateral to include the skin margin 
    • medial to include medial skin margin 
  • orientation  
    • portrait
  • detector size
    • 18 cm x 24 cm
  • exposure
    • 50-60 kVp
    • 2-5 mAs
  • SID
    • 100 cm
  • grid
    • no 
  • the elbow is in an AP position, with slight internal rotation.
  • patient's arm should be rotated externally to ensure that the trochlea and capitulum are seen in profile. 

At times, patients may not be able to fully extend their elbow joint. In such cases, partial flexion may be used at the joint; at initial presentation two AP views may then be required (the first with the forearm flat against the detector, the second with the humerus flat against the detector).

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Cases and figures

  • Figure 1: right elbow AP positioning
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  • Case 1: normal elbow
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  • Case 2: right elbow joint effusion
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  • Case 3: elbow fracture-dislocation - terrible triad
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  • Case 4: lateral epicondyle fracture
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  • Case 5: gouty tophus
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  • Case 6: rheumatoid arthritis
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