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Elbow X-Rays


Don’t be bamboozled by paediatric elbow x-rays.  Here’s a guide to a systematic approach. (Click on the images to see them at full size).

1. Check your lateral is really a lateral

Look for the hourglass sign or ‘figure-of-eight’ which shows that you are actually looking at a true lateral.


2. Look for an anterior fat pad

A small one is normal but a large one (sail sign) suggests intra-articular injury.

Anterior fat pad

3. Look for a posterior fat pad

Pretty much always abnormal, and indicates a fracture in 75%.

Posterior fat pad

4.  Check the anterior humeral line

Draw a line down the anterior border of the humerus.  It should go through the middle third of the capitellum.

Anterior humeral line

Displacement suggests a probable fracture (if there is no figure of eight then this line isn’t accurate).

Anterior humeral line displacement

5. Check the radio-capitellar line

Draw a line through the middle of the proximal end of the radius – it should bisect the capitellum in lateral and AP views.


Displacement indicates a radial head dislocation.

Radial head displacement

6. Look at the angle of the radial head

Look for any subtle angulation at the radial head which can indicate a fracture.

Radial head angle

7. Check the cortex lines of the distal humerus

Look for any disruption of the cortex on the anterior or posterior humeral borders.  This would usually be accompanied by fat pads or displacement of the anterior humeral line.

humeral borders

8. Go through all the ossification centres

Check that the ossification centres are appropriate.  Use CRITOE: capitellum (1); radial head (3); internal epicondyle (5); trochlear (7); olecranon (9); external epicondyle (11).





USM Orthopaedic

Radiology Assistant

NYP Emergency


  • Tessa Davis is a Consultant in Paediatric Emergency Medicine at the Royal London Hospital and a Senior Lecturer at Queen Mary University of London.

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6 thoughts on “Elbow X-Rays”

  1. The figure of 8 appears to be a good interpretation. Is there any other evidence or research around this assessment criteria?

  2. Pingback: The LITFL Review 118 - LITFL