Collar sign in spondylolysis

Last revised by Mohammadtaghi Niknejad on 30 Jan 2022

The Collar sign in spondylolysis refers to a break in the pars interarticularis of the vertebra on oblique radiographs that can have the appearance of a collar around the Scotty dog's neck.

  • unilateral or bilateral
  • 90% seen at the L5 level and less than10% noted at the L4 level1,2
  • 65% of patients may progress to spondylolisthesis1

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Cases and figures

  • Case 1
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