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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 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. 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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