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Dagger Sign
Ankylosing Spondylitis
General Considerations
- Ossification of the supraspinous and interspinous ligaments
- Seen on frontal radiographs of the spine
- Occurs in ankylosing spondylitis
Other Radiologic Features of Ankylosing Spondylitis
- Sacroiliitis
- Enthesophytes
- Squaring of the vertebral body
- Flowing syndesmophyte formation (bamboo spine)
- Arthritis of the apophyseal joints
- Bilateral, symmetric narrowing of the hips, knees or shoulders resembling a hypertrophic arthritis
- Apical pulmonary fibrosis
- Erosions and periostitis of the hands
![Dagger sign](../../images/boneimages1/daggersign.jpg)
Dagger Sign of Ankylosing Spondylitis. There is ossification of the supraspinous and interspinous ligaments (red arrows) resembling a dagger. There is also fusion of both SI joints (black arrows) and the symphysis pubis (white arrow).
![Dagger Sign of Ankylosing Spondylitis](../../images/boneimages1/dagger sign-ankylosing spondylitis-ann.jpg)
Dagger Sign of Ankylosing Spondylitis. There is ossification of the supraspinous and interspinous ligaments (white arrows) resembling a dagger. There is also fusion of both SI joints.
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