What are the early radiographic signs of ankylosing spondylitis (AS)?

Updated: Feb 02, 2021
  • Author: Lawrence H Brent, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

The radiographic signs of AS are due to enthesitis, particularly of the annulus fibrosus. Early radiographic signs include squaring of the vertebral bodies caused by erosions of the superior and inferior margins of the vertebral bodies, resulting in loss of the normal concave contour of the anterior surface of the vertebral bodies (see the images below). The inflammatory lesions at vertebral entheses may result in sclerosis of the superior and inferior margins of the vertebral bodies, called shiny corners (Romanus lesion).

Enthesitis at the site of the insertion of the annulus fibrosis on the corners of the vertebral bodies, shiny corner (Romanus) lesions.

Enthesitis at the site of the insertion of the ann Enthesitis at the site of the insertion of the annulus fibrosis on the corners of the vertebral bodies, shiny corner (Romanus) lesions.

Ossification of the annulus fibrosus leads to the radiographic appearance of syndesmophytes, which in AS are typically marginal. Over time, the development of continuous (bridging) syndesmophytes may result in complete fusion (bamboo spine), which is essentially fused (see the images below).

Anteroposterior radiograph of spine of a patient with AS.

Anteroposterior radiograph of spine of a patient w Anteroposterior radiograph of spine of a patient with AS.

 

Anteroposterior (left) and lateral (right) radiographs of a patient with AS.

Anteroposterior (left) and lateral (right) radiogr Anteroposterior (left) and lateral (right) radiographs of a patient with AS.

Anteroposterior radiograph of spine of a patient with AS. Ossification of annulus fibrosus can be observed at multiple levels, which has led to fusion of spine with abnormal curvature.

Anteroposterior radiograph of spine of a patient w Anteroposterior radiograph of spine of a patient with AS. Ossification of annulus fibrosus can be observed at multiple levels, which has led to fusion of spine with abnormal curvature.

This radiograph of the lumbar spine of a patient with end-stage AS shows bridging syndesmophytes, resulting in bamboo spine.

This radiograph of the lumbar spine of a patient w This radiograph of the lumbar spine of a patient with end-stage AS shows bridging syndesmophytes, resulting in bamboo spine.

This radiograph of the cervical spine of a patient with AS shows fusion of the vertebral bodies due to bridging syndesmophytes.

This radiograph of the cervical spine of a patient This radiograph of the cervical spine of a patient with AS shows fusion of the vertebral bodies due to bridging syndesmophytes.

Spinal disease associated with inflammatory bowel disease (IBD) is similar to AS with bilateral symmetric sacroiliitis and gradually ascending spondylitis and marginal syndesmophytes. On the other hand, reactive arthritis (ReA) and psoriatic arthritis (PsA) typically exhibit asymmetric sacroiliitis and discontinuous spondylitis with nonmarginal syndesmophytes.


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