Lecture Notes: Ankylosing Spondylitis

Overview

• Ankylosing Spondylitis (AS) is an inflammatory condition primarily affecting the spine.
• Part of the seronegative spondyloarthropathies.
• Strongly associated with the HLA-B27 gene.

Key Joints Affected

• Sacroiliac joints
• Vertebral column joints
• Inflammation causes pain and stiffness, progressing to joint fusion.
• Bamboo spine: Classical finding on X-ray due to fusion.

Genetic Links

• 90% of patients with AS have the HLA-B27 gene.
• Only 2% of HLA-B27 positive individuals develop AS.
• Risk increases to 20% with a first-degree relative affected.

Patient Presentation

• Typically young adult males (late teens to 20s).
• Male to female ratio: 3:1.
• Symptoms develop gradually over >3 months:
  • Low back pain and stiffness
  • Sacroiliac pain (buttock region)
  • Pain worsens with rest, improves with movement.
  • Worse at night and morning; may take 30 minutes to improve.
• Symptoms fluctuate with periods of flares and improvement.

Complications

• Vertebral fractures.
• Systemic symptoms: weight loss, fatigue.

Associations with Other Conditions

• Chest pain (costovertebral and costosternal joints).
• Enthesitis: Inflammation at tendon/ligament insertion.
• Conditions include:
  • Plantar fasciitis
  • Achilles tendonitis
  • Dactylitis (inflammation of entire finger/toe)
  • Anemia
  • Anterior uveitis
  • Aortitis
  • Heart block
  • Restrictive lung disease
  • Pulmonary fibrosis (upper lobes) in ~1% of patients
  • Inflammatory bowel disease

Diagnostic Tests

• Schober's Test: Assesses lumbar spine mobility.
  • Patient marks at L5 vertebra.
  • Distance between points (10 cm above, 5 cm below) should exceed 20 cm when bending.

Investigations

• Inflammatory markers: CRP, ESR.
• Genetic test for HLA-B27 gene.
• X-rays for spine and sacrum.
• MRI for early changes (bone marrow edema).
• X-ray changes: Bamboo spine, squaring of vertebral bodies, subchondral changes, syndesmophytes.

Management

Medical Management

• NSAIDs: Ibuprofen, naproxen.
• Steroids: During flares (oral, intramuscular, or joint injection).
• Anti-TNF medications: Etanercept, infliximab, adalimumab, certolizumab.
• Interleukin-17 antibody: Secukinumab (new treatment option).

Additional Management

• Physiotherapy: Essential for mobility and flexibility.
• Smoking cessation.
• Bisphosphonates for osteoporosis.
• Treatments for complications (e.g., heart block).
• Surgery: For spinal deformities or fractures.

Resources and Support

• Zero to Finals website offers additional resources, illustrations, practice questions, and a blog.
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