Chalkstick fracture in ankylosing spondylitis

Case contributed by Vikas Shah


Background of ankylosing spondylitis. Severe pain in back following a light fall.

Patient Data

Gender: Male

Lumbar spine x-ray


Both views show classic signs of ankylosing spondylitis:

  • dagger spine sign of continuous ossification of the interspinous and supraspinous ligaments
  • squared vertebral bodies
  • bamboo spine sign due to continuous syndesmophytes
  • fused sacroiliac joints

The dagger is broken on the AP view indicating a fracture at this location. The lateral view confirms this.

The CT confirms a three-column fracture at L3 level and the other signs of ankylosing spondylitis.

Case Discussion

These fractures are known as "chalkstick" fractures because of how brittle the spine becomes in ankylosing spondylitis, and can occur with minimal trauma. They usually occur at the cervicothoracic or thoracolumbar junctions.

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