Rheumatology
Ankylosing Spondylitis
강직성척추염
Chronic inflammatory arthritis of sacroiliac joints and spine
- How common
- 0.1–0.5% (3:1 male)
- Typical age
- Onset 20s–40s
What is it?
HLA-B27 genetic susceptibility plus IL-23/Th17 axis activation drives chronic enthesitis leading to spinal ankylosis and syndesmophyte formation.
Commonly affected: Sacroiliac joints, spine, peripheral entheses
How it develops
- HLA-B27 susceptibility>90% of patients HLA-B27 positive
- EnthesitisInflammation at ligament/tendon insertions
- IL-17/IL-23 activationTh17-mediated chronic inflammation
- New bone & ankylosisSyndesmophytes cause spinal ankylosis (bamboo spine)
Symptoms
- Inflammatory back painMorning worse, improves with exercise, >3 months
- Morning stiffness >30 minImproves with activity
- Sacroiliac painAlternating buttock/back pain
- Reduced spinal mobilityPositive Schober test, reduced chest expansion
- Extra-articularUveitis, IBD, psoriasis, aortitis
How it is examined
- ASAS classificationSacroiliitis on imaging or HLA-B27 + clinical features
- Schober testLumbar flexion <5cm increase from L5+10cm
- Chest expansionAt 4th intercostal space <2.5cm
Imaging
Pelvic X-ray shows bilateral sacroiliitis (NY criteria); late: bamboo spine.
- Bilateral sacroiliitis
- Syndesmophytes
- Bamboo spine
- Sacral fusion
MRI detects early sacroiliitis (bone marrow edema) when X-ray negative.
- SI joint bone marrow edema
- Synovitis
- Enthesitis
Non-surgical care
- NSAIDs (first-line)Continuous use may slow progression
- Exercise + physiotherapyCornerstone for maintaining spinal mobility
- Smoking cessationSmoking accelerates progression
- Sulfasalazine (peripheral)Effective only for peripheral arthritis
- Local steroid injectionFor enthesitis or active sacroiliitis
Conservative options are generally tried first. Medications listed here can have side effects — discuss them with your prescriber.
When surgery is considered
NSAID failure or active inflammation on imaging
Procedures that may be discussed
- TNF inhibitors (etanercept, infliximab, adalimumab, golimumab)
- IL-17 inhibitors (secukinumab, ixekizumab)
- JAK inhibitors (tofacitinib, upadacitinib)
- Spinal fracture surgery, hip replacement
Outlook
Most live normal lifespan. Early treatment slows ankylosis. Increased fracture and CV risk.