Ankylosing spondylitis

Definition and Epidemiology

• Chronic inflammatory arthritis primarily affecting the spine and sacroiliac joints.
• Part of the spondyloarthritis group, characterised by spinal fusion due to bony growths (syndesmophytes).
• More prevalent in males; onset usually in early adulthood.
• Strong genetic link, with about 90% of Caucasian patients being HLA-B27 positive.

Pathophysiology

• Exact cause unknown; involves genetic, immunological, and environmental factors.
• Inflammation starts at entheses (ligament and tendon attachment points).
• Chronic inflammation leads to scarring and ossification, causing stiffness and fusion in the spine.

Clinical Features

• Gradual onset of low back pain and stiffness, worse in the morning or after inactivity.
• Pain improvement with exercise.
• Potential involvement of peripheral joints.
• Extra-articular manifestations like uveitis, psoriasis, and inflammatory bowel disease.

Diagnosis

• Based on clinical signs, radiographic findings, and HLA-B27 status.
• Imaging: X-ray for sacroiliitis, MRI for early changes.
• Inflammatory markers (CRP, ESR) may be elevated but are not definitive.

Management

• Non-pharmacological: Emphasis on physiotherapy and regular exercise.
• Pharmacological:
  • NSAIDs as first-line for pain and stiffness.
  • DMARDs (e.g., sulfasalazine) for peripheral symptoms.
  • Biologics (e.g., TNF inhibitors) for refractory cases.
• Surgical: Osteotomy or joint replacement in advanced cases.

Prognosis

• Wide variability in symptom severity and disease progression.
• Early treatment and regular monitoring can manage symptoms and slow progression.