Posterior fat pad sign (elbow)

Last revised by Leonardo Lustosa on 15 Jan 2023

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 ref

In the setting of trauma, it suggests an occult non-displaced fracture. In children, it most often indicates a supracondylar fracture, other common fractures are those of the proximal ulna, lateral condyle, and radial neck 2. In adults, look for a radial head fracture ref

See also

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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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  • Case 5: annotated
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  • Case 6
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