Collar sign in spondylolysis

Case contributed by Mohammad Taghi Niknejad
Diagnosis certain

Presentation

Work up for low back pain.

Patient Data

Age: 20 years
Gender: Female
x-ray

There is a break in the left pars interarticularis of the L4 vertebra on the oblique radiograph that resembles a collar around the Scotty dog's neck. 

A suspected break is also noted in the left pars interarticularis of the L5 vertebra.

Case Discussion

The Collar sign in spondylolysis refers to a break in the pars interarticularis of the vertebra on oblique radiographs that could be seen as unilateral or bilateral.

About 90% of spondylolysis were seen at the L5 level, and less than10% were noted at the L4 level if bilateral 65% of patients may progress to spondylolisthesis.

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