Lightbulb sign (shoulder dislocation)

Dr Andrew Dixon et al.

The lightbulb 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 lightbulb when viewed from the front 1.

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Article information

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

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Cases and figures

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    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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