Ankylosing spondylitis (AS) is a chronic inflammatory disease that primarily affects the spine and sacroiliac joints, leading to pain, stiffness, and, in severe cases, fusion of the vertebrae (1). It is classified under the broader category of axial spondyloarthritis and is a systemic condition that can also impact peripheral joints, entheses (sites where tendons and ligaments attach to bone), and extra-articular systems such as the eyes, heart, and gastrointestinal tract. The disease typically begins in early adulthood and has a progressive, albeit highly variable, clinical course (1).
Symptoms
The hallmark symptom of ankylosing spondylitis is chronic back pain and stiffness, particularly in the lower back and hips (2). These symptoms are typically worse in the morning or after periods of inactivity and may improve with exercise.
Other common symptoms include:
• Pain in the sacroiliac joints (where the spine meets the pelvis)
• Limited spinal mobility or postural changes (e.g., kyphosis)
• Pain and swelling in peripheral joints (e.g., shoulders, knees)
• Fatigue and reduced functional capacity
• Enthesitis, particularly at the heel or Achilles tendon
• Uveitis (eye inflammation), which may present as eye pain, redness, or blurred vision
• In advanced cases, spinal segments may fuse (ankylosis), leading to a significant loss of flexibility and posture changes (2)
Causes
The exact cause of ankylosing spondylitis is not fully understood, but it is believed to result from an interaction between genetic predisposition and environmental triggers. The strongest known association is with the HLA-B27 gene, found in over 85–90% of individuals with AS in some populations. However, not all HLA-B27 positive individuals develop the disease, indicating that other genetic and environmental factors are involved (2).
Risk Factors
Several factors increase the risk of developing ankylosing spondylitis:
• Genetics: A family history of AS significantly raises the risk
• HLA-B27 status: Presence of the HLA-B27 gene is the strongest known genetic risk factor
• Age: Onset usually occurs between ages 15 and 40
• Sex: AS is more commonly diagnosed in men, although women may have a different or less typical disease course
• Ethnicity: Certain ethnic groups, such as people of Northern European descent, have higher prevalence rates of HLA-B27 and AS
Diagnosis
Diagnosing ankylosing spondylitis can be challenging, particularly in the early stages. Diagnosis is based on a combination of clinical evaluation, imaging, and laboratory findings.
Key diagnostic tools include:
• Medical history and physical examination, focusing on patterns of inflammatory back pain and reduced spinal mobility
• Imaging: X-rays can reveal sacroiliitis and syndesmophyte formation. MRI is more sensitive and can detect early inflammatory changes before structural damage is evident
• Laboratory tests: HLA-B27 testing, markers of inflammation (e.g., ESR, CRP), and ruling out other conditions
• Classification criteria: The Modified New York Criteria or the ASAS (Assessment of SpondyloArthritis International Society) Criteria may be used to support diagnosis
Treatment Options
While there is no cure for ankylosing spondylitis, treatment focuses on managing symptoms, reducing inflammation, and maintaining function. A multidisciplinary approach often yields the best outcomes (2).
Treatment options include:
Medications
• NSAIDs (e.g., naproxen, indomethacin) are the first-line treatment for pain and stiffness
• TNF inhibitors (e.g., etanercept, adalimumab) and IL-17 inhibitors (e.g., secukinumab) are biologics used in patients with inadequate response to NSAIDs
• DMARDs (e.g., sulfasalazine) may be used for peripheral joint involvement but are generally less effective for axial symptoms
• Corticosteroids may be used selectively for acute flare-ups or extra-articular involvement (3)
Physical Therapy and Exercise
• Regular, supervised exercise is vital to preserve spinal mobility, posture, and respiratory function
• Physiotherapy may include stretching, strengthening, and posture correction (3)
Surgical Interventions
• Rare, but may be considered in cases of severe joint damage or spinal deformity
Living With or Prevention
Living with ankylosing spondylitis requires long-term management strategies that promote mobility, independence, and quality of life (3).
Key considerations include:
• Physical activity: Daily exercise routines, including stretching and low-impact aerobic activity, help maintain function and reduce stiffness
• Postural awareness: Maintaining good posture and sleeping on a firm mattress can reduce deformities
• Eye health: Regular ophthalmologic check-ups are important due to the risk of uveitis
• Smoking cessation: Smoking accelerates disease progression and reduces medication effectiveness
• Support networks: Connecting with patient support groups or counseling services can aid coping
While there is no known way to prevent ankylosing spondylitis entirely, early diagnosis and proactive management can delay progression, minimize disability, and improve quality of life (3).
References
1. Sieper J, Braun J, Rudwaleit M, Boonen A, Zink A. Ankylosing spondylitis: an overview. Ann Rheum Dis. 2002;61(Suppl 3)\:iii8-18.
2. Wenker KJ, Quint JM. Ankylosing Spondylitis. StatPearls \[Internet]. 2025.
3. Agrawal P, et al. Diagnosis and Treatment of Ankylosing Spondylitis. 2024.