What is ankylosing spondylitis (AS)?

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Last updated: April 19, 2025View editorial policy

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From the Guidelines

Ankylosing spondylitis is a chronic inflammatory disease characterized by sacroiliitis, enthesitis, and a marked propensity for sacroiliac joint and spinal fusion, belonging to the spondyloarthritis family of diseases. According to the most recent evidence from 1, this condition is distinguished by universal involvement with sacroiliac joint inflammation or fusion, and more prevalent spinal ankylosis. The disease causes inflammation where ligaments and tendons attach to bones, leading to bone erosion and new bone formation that can eventually cause vertebrae to fuse together (ankylosis), resulting in a rigid spine.

Key Characteristics

  • Chronic inflammatory arthritis
  • Sacroiliitis, enthesitis, and spinal fusion
  • Part of the spondyloarthritis family of diseases
  • Typically begins in early adulthood, affecting men more frequently than women

Common Symptoms

  • Lower back pain and stiffness that worsen with rest and improve with activity
  • Fatigue
  • Pain that may radiate to the buttocks or backs of thighs
  • Inflammation in other areas like the eyes (uveitis), heart, lungs, or peripheral joints

Treatment

  • Nonsteroidal anti-inflammatory drugs (NSAIDs) like naproxen or indomethacin for pain and inflammation
  • Physical therapy to maintain flexibility
  • Biologics such as TNF inhibitors (adalimumab, etanercept, infliximab) or IL-17 inhibitors (secukinumab, ixekizumab) for more severe cases
  • Regular exercise, good posture practices, and smoking cessation as important lifestyle modifications to manage symptoms and slow disease progression, as recommended by 1.

From the Research

Definition and Characteristics of Ankylosing Spondylitis

  • Ankylosing spondylitis (AS) is a chronic inflammatory autoimmune disease that primarily affects the spine joints, leading to severe, chronic pain 2.
  • In advanced cases, AS can cause spine fusion, significantly impacting the patient's quality of life 2.
  • The disease is characterized by lower back pain, enthesitis, and asymmetrical peripheral arthritis 3.

Pathogenesis and Etiology

  • The pathogenesis of AS remains unclear, but immune cells and innate cytokines, such as human leukocyte antigen (HLA)‑B27 and the interleukin‑23/17 axis, are thought to play a crucial role 2.
  • Genome-wide association studies and cytokine pathways have been reviewed to better understand the etiology and pathogenesis of AS 2.

Treatment and Management

  • Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended as a first-line treatment for AS, and have been shown to be effective in reducing pain severity and improving disease activity 3.
  • NSAIDs, such as etoricoxib, celecoxib, meloxicam, diclofenac, naproxen, and beta-D-mannuronic acid (M2000), have been compared in terms of efficacy and safety, with etoricoxib ranked as the most efficacious treatment for patients with AS 3.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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