Syndesmophytes are calcifications or heterotopic ossifications inside a spinal ligament or of the annulus fibrosus. They are seen in only a limited number of conditions including:
They can be classified as marginal (along the margins of the vertebral bodies) or non marginal (larger and bulky away from the vertebral bodies). Ankylosing spondylitis classically displays symmetrical marginal syndesmophytes.
Appearance on plain radiographs comprises vertical and symmetrical calcification of the lateral margins of the intervertebral disc space.
- syndesmophyte: paravertebral ossifications that run parallel with the spine c.f. osteophytes which typically protrude perpendicular to the spine
- enthesophyte: located at an attachment of a ligament or tendon, not associated with a joint