Ankylosing spondilitis

Case contributed by Aditya Shetty


lower back stiffness

Patient Data

Age: 25
Gender: Male

X-ray findings:

  • Dense vertical line in the midline 
  • Marginal syndesmophytes along the thoraco-lumbar spine


Annotated image

Yellow arrows indicate the dense white line caused by ossification of interspinous and supraspinous ligaments ; It is referred to as 'Dagger sign'

Red arrows indicate marginal syndesmophytes causing fusion (ankylosis) of vertebrae. The resulting appearance of spine is referred to as 'Bamboo spine'

Case Discussion

Case of ankylosing spondilitis, which is a seronegative spondyloarthropathy and HLA-B 27 positive ( >90% of cases).

Sacroilitis is the hallmark of this condition represented by fusion of S-I joints bilaterally. This finding is not well appreciated in the AP images do to overlying bowel gas. 

Xray taken after a bowel preparation would help

However the other findings and signs , consistent with the condition, are present.

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