Joints
What Are the Findings?
What is the Diagnosis?
2. Findings and Diagnosis
CT of the thoracic spine in a 78-year-old male with Ankylosing Spondylitis demonstrates the classical imaging findings of spinal ankylosis.
Image a: Axial CT through the thoracic spine shows a syndesmophyte involving the anterior longitudinal ligament (white arrowheads) and calcification of the interspinous ligament (yellow arrowheads).
Image b: Magnified axial view further highlights the anterior and posterior ligamentous ossification.
Image c: Coronal reconstruction reveals multiple syndesmophytes, forming osseous bridges across adjacent vertebral bodies.
Image d: Magnified coronal view demonstrates a prominent syndesmophyte as a continuous bony connection between two vertebrae (white arrows), consistent with advanced AS.
✳️ Editorial Note:
The hallmark of Ankylosing Spondylitis is inflammation at entheses—the sites where ligaments and tendons attach to bone. The disease often begins in the sacroiliac joints, then ascends through the lumbar and thoracic spine, following the course of major spinal ligaments.
The anterior longitudinal ligament, interspinous ligaments, and posterior spinal elements become sites of chronic inflammation and subsequent ossification, leading to:
Syndesmophytes that bridge vertebral bodies
Bony fusion that produces the classic “bamboo spine”
Loss of flexibility and chest expansion, especially with costovertebral joint involvement
This ascending, enthesopathic process transforms the spine from a flexible column into a rigid rod, with the SI joints as its ground zero.
Ashley Davidoff, MD TheCommonVein.com (b12542-05 | 9315Lu)