Dagger Sign

(1) Lumbar dagger A term referring to a single central radiodense line on frontal radiographs related to ossification of supraspinous and interspinous ligaments, corresponding to the lumbar spine in bony fusion of the adjacent vertebrae with syndesmophyte formation, which is characteristic of ankylosing spondylitis
(2) A feature seen in imaging in patients with ossification of the posterior longitudinal ligament (OPLL) with spinal cord compression due to a dense, vertical ossified 1–5-mm wide strip or plaque at the posterior margin of the vertebral body and intervertebral disks; usually in the cervical spine, ossification may appear at T4 to T7
References in periodicals archive ?
The trolley track sign derives from the 2 lateral lines of ossification representing the apophyseal joint capsules, and the dagger sign from the central line of ossification visible on the AP view.