A sign of lumbar disk herniation recognizable on lateral CT generated digital radiograms.

Computed tomography is a very sensitive and fairly specific imaging mode for diagnosing herniated disks in patients with low back pain and radiculopathy. We describe a new CT sign associated with posterior disk herniation that consists of a bony defect on the lower posterior angle of the proximal vertebral body and endplate shown on CT generated digital radiograms. This finding, by no means constant, is encountered frequently enough to be described as a sign of posterior disk protrusion. It often occurs concomitantly with posterior avulsion of a bone fragment probably related to avascular bone necrosis of the posterior inferior angle of the endplate.