Light bulb sign (posterior shoulder dislocation)

The light bulb sign refers to the abnormal AP radiograph appearance of the humeral head in posterior shoulder dislocation.

When the humerus dislocates it also internally rotates such that the head contour projects like a light bulb when viewed from the front 1.

See also

Inspired signs

Article information

rID: 18811
Section: Signs
Tag: refs, refs
Synonyms or Alternate Spellings:
  • Lightbulb sign - shoulder
  • Light-bulb sign - humerus
  • The lightbulb sign - shoulder

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Cases and figures

  • Figure 1: a traditional light bulb
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  •  Case 1
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  • Case 2: lightbulb sign - posterior shoulder dislocation
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  • Case 3
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  • Case 4
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