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Ankylosing spondylitis (AS) is a chronic, systemic, inflammatory spondyloarthropathy that primarily affects the axial skeleton—notably the sacroiliac joints and spine.
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Ankylosing spondylitis - causes, symptoms, diagnosis, treatment, pathology
https://www.youtube.com/watch?v=Afy1iKVg8sc&t=7s
https://www.youtube.com/watch?v=a23A3nAaO0E
https://www.youtube.com/watch?v=1GEuXDShhTI
https://www.youtube.com/watch?v=GDa224AXo6Y
| Feature | Description |
|---|---|
| Cause | Autoimmune, with strong genetic predisposition |
| HLA-B27 | Present in ~90–95% of Caucasian patients with AS |
| Enthesitis | Inflammation at bony insertion sites → syndesmophyte formation |
| Ossification | Leads to spinal rigidity and eventual ankylosis |
Spine spondyloarthritis progression from acute inflammation to chronic changes. MRI depicts early-stage lesions, but is not as good as CT and radiography to determine chronic structural changes.
Castro, S. Axial spondyloarthritis – the role of imaging in diagnosis and management. ESSR 2017 EPOS. Published June 9, 2017. Accessed August 28, 2025. https://epos.myesr.org/poster/esr/essr2017/P-0303
| Parameter | Value / Notes |
|---|---|
| Onset age | Typically between 15–40 years |
| Sex ratio | M > F (2–3:1) |
| Ethnic predisposition | Higher in Caucasians with HLA-B27 |
| Feature | Description |
|---|---|
| Chronic low back pain | Insidious onset, improves with activity, worse with rest |
| Morning stiffness | >30 minutes, improves with exercise |
| Loss of spinal mobility | ↓ lumbar flexion, ↑ thoracic kyphosis |
| Sacroiliac pain | Often the first symptom |
| Extra-articular features | Uveitis, aortic regurgitation, pulmonary fibrosis, enthesitis |