Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the spine and sacroiliac joints, leading to pain, stiffness, and potential fusion of the vertebrae. It’s a type of axial spondyloarthritis, often associated with the HLA-B27 gene, and typically begins in young adulthood.
Key Features:
Symptoms:
Chronic lower back pain and stiffness, worse in the morning or after inactivity, improving with movement.

Pain in hips, shoulders, or other joints.

Extra-articular manifestations: uveitis (eye inflammation), enthesitis (inflammation at tendon/ligament insertions), psoriasis, or inflammatory bowel disease.

Fatigue and reduced mobility.

Progression: May lead to spinal fusion (ankylosis), causing a rigid spine and kyphosis (forward curvature).

Common Sites: Sacroiliac joints, spine, and peripheral joints (less commonly).

Diagnosis:
Clinical Criteria: Inflammatory back pain (onset before age 40, lasting >3 months, improving with exercise, worse at rest), limited spinal mobility, or reduced chest expansion.

Imaging:
X-rays: Sacroiliitis (erosion or fusion of sacroiliac joints), “bamboo spine” (syndesmophytes bridging vertebrae).

MRI: Detects early inflammation not visible on X-rays.

Lab Tests:
HLA-B27 positive in ~90% of cases (not diagnostic alone).

Elevated C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) in active disease.

Diagnostic Guidelines: Modified New York criteria or ASAS (Assessment of SpondyloArthritis international Society) criteria.

Treatment:
Medications:
NSAIDs (e.g., ibuprofen, naproxen): First-line for pain and inflammation.

Biologics:
TNF inhibitors (e.g., etanercept, adalimumab) for moderate-to-severe disease.

IL-17 inhibitors (e.g., secukinumab) for those unresponsive to TNF inhibitors.

DMARDs (e.g., sulfasalazine): For peripheral joint involvement, less effective for axial disease.

Corticosteroids: Short-term use for flares or uveitis.

Non-Pharmacologic:
Physical therapy and exercise to maintain mobility and posture.

Smoking cessation (smoking worsens disease progression).

Surgery: Rare, for severe deformities (e.g., spinal osteotomy) or joint replacement (e.g., hips).

Monitoring: Regular follow-ups to assess disease activity, spinal mobility, and treatment response.

Epidemiology:
Affects ~0.5-1% of the population, more common in men (2-3:1 ratio).

Onset typically between ages 20-40.

Strong association with HLA-B27, but not all carriers develop AS.

Complications:
Spinal fusion and loss of mobility.

Osteoporosis and increased fracture risk.

Cardiovascular disease (e.g., aortitis, increased risk of heart disease).

Uveitis, leading to vision issues if untreated.

Prognosis:
Variable; some experience mild symptoms, while others develop significant disability.

Early diagnosis and treatment (especially biologics) improve outcomes and quality of life.

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Disclaimer: Owerl is not a doctor; please consult one.