Aortic-vertebral interaction in ankylosing spondylitis: syndesmophyte development at the juxta-aortic vertebral rim.
OBJECTIVES
The aorta inhibits paravertebral ossification in diffuse idiopathic skeletal hyperostosis. We investigated if syndesmophytes in ankylosing spondylitis (AS) occurred less often at the vertebral rim near the aorta.


METHODS
We performed thoracolumbar CT scans in 60 subjects in this cross-sectional study. The mid-thoracic spine was also scanned in 22 subjects. We divided the rim of each intervertebral disc space (IDS) into 72 angular sectors, each of 5°. We computed syndesmophyte height in each sector, and the distance from the sector to the aorta. We evaluated if syndesmophyte size or frequency in a sector was associated with its distance from the aorta.


RESULTS
In the 180° region of the vertebral rim centered on the sector closest to the aorta, syndesmophyte height and/or frequency varied with the distance of the sector to the aorta, with the lowest frequency and smallest mean syndesmophyte height at the sector along the rim nearest the aorta. Additionally, syndesmophytes were less common in subjects and at IDSs where the aorta was anatomically closer to the vertebra. No syndesmophytes were present in the sector closest to the aorta in subjects whose aorta-vertebral distance was less than 2 mm, but syndesmophytes were progressively more common among subjects whose aortas lay further from the rim.


CONCLUSIONS
Syndesmophytes occurred less commonly and were smaller at the thoracolumbar vertebral rim near the aorta. These findings suggest that mechanical factors extrinsic to the spine and not solely vertebral inflammation, influence syndesmophyte development in AS.
['Tan|Sovira|S|', 'Dasgupta|Abhijit|A|', 'Flynn|John A|JA|', 'Ward|Michael M|MM|0000-0003-1857-9367']
D000328:Adult D000368:Aged D001011:Aorta D001837:Body Weights and Measures D003430:Cross-Sectional Studies D005260:Female D006801:Humans D007403:Intervertebral Disc D008297:Male D008875:Middle Aged D013167:Spondylitis, Ankylosing D013904:Thoracic Vertebrae D014057:Tomography, X-Ray Computed D055815:Young Adult
ankylosing spondylitis syndesmophyte aorta