Posterior fat pad sign (elbow)

Last revised by Dr Yahya Baba on 09 Feb 2021

The posterior fat pad sign is the visualization of a lucent crescent of fat located in the olecranon fossa on a true lateral view of an elbow joint with the elbow flexed at a right angle indicating an elbow joint effusion. Normally, the posterior fat pad will not be seen in this view. 

In the setting of trauma, it suggests an occult non-displaced fracture. In children, a supracondylar fracture should be suspected. In adults, look for a radial head fracture

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Cases and figures

  • Figure 1 - elbow joint effusion
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  • Case 1: with radial head fracture
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  • Case 2: radial head fracture
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  • Case 3: radial head fracture
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  • Case 4: supracondylar fracture
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