Sail sign (elbow)

The sail sign on an elbow radiograph, also known as the anterior fat pad sign, describes the elevation of the anterior fat pad to create a silhouette similar to a billowing spinnaker sail from a boat. It indicates the presence of an elbow joint effusion.

The anterior fat pad is usually concealed within the coronoid fossa or seen paralleling the anterior humeral line.  When there is a joint effusion, the anterior fat pad (which is intra-articular, but extrasynovial) becomes elevated.

Elevation of the anterior fat pad usually heralds the presence of an intra-articular fracture. In adults, this is usually a radial head fracture whereas in children, the commonest cause of a raised elbow fat pad is a supracondylar fracture

Where a fat pad is raised and no fracture is demonstrated, an occult fracture should be suspected.

Video tutorial

See also

Inspired signs

Article information

rID: 2014
Section: Signs
Tag: elbow
Synonyms or Alternate Spellings:
  • Anterior fat pad sign
  • Sail sign - elbow
  • Elbow sail sign
  • Sail sign of elbow

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Cases and figures

  • Fig 1: sail boat
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  • Case 1
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  • Figure 1
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  •  Case 3
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  • Case 2
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  • Case 4: MRI equivalent
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  • Case 5
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  • Supracondylar fra...
    Case 7
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  •  Case 6
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