The presence of a scotty dog sign on oblique lumbar radiographs indicates which condition?

• A. Pars interarticularis stress fracture (spondylolysis)
• B. Spondylolisthesis
• C. Disc herniation
• D. Spinal stenosis

Answer: (A)

The Scotty dog sign on an oblique lumbar radiograph points to a pars interarticularis fracture, known as spondylolysis. On that oblique view, the vertebral elements resemble a Scottie dog, with the pars interarticularis forming the neck. A fracture through the pars appears as a collar around the neck, which is the Scotty dog sign. This finding is classic for a pars interarticularis stress fracture, common in young athletes from repetitive hyperextension and loading. If the pars defect is bilateral, it can lead to spondylolisthesis, but the sign itself specifically indicates pars fracture. Disc herniation and spinal stenosis involve different pathologies and are not diagnosed by this radiographic sign; they’re usually assessed with MRI or CT and have other imaging features.