Axial spondyloarthritis

Overview

Axial Spondyloarthritis (axSpA) is a chronic, inflammatory rheumatic disease that primarily affects the spine and sacroiliac joints (the joints connecting the spine to the pelvis). It belongs to the spondyloarthritis (SpA) family of disorders, which also includes psoriatic arthritis, reactive arthritis, and arthritis associated with inflammatory bowel disease.

AxSpA is broadly classified into two categories:

• Radiographic axSpA (Ankylosing Spondylitis): When structural damage is visible on X-ray

• Non-radiographic axSpA: When no structural changes are seen on X-ray but symptoms and MRI findings are present

Early diagnosis and treatment are essential to reduce pain, preserve mobility, and prevent progression.

Causes

The exact cause of axial spondyloarthritis is unknown, but it is believed to result from a combination of genetic and environmental factors.

Key factors include:

• HLA-B27 gene: Present in over 80% of individuals with axSpA; strongly linked to disease risk

• Immune system dysregulation: Leads to chronic inflammation of the spine and joints

• Environmental triggers: Gut bacteria or infections may activate immune responses in genetically predisposed individuals

Symptoms

Symptoms typically begin in early adulthood (before age 45) and progress gradually. Key features include:

Axial (spinal) symptoms:

• Chronic low back pain that improves with activity but not with rest

• Morning stiffness lasting more than 30 minutes

• Pain and stiffness in the buttocks or sacroiliac joints

• Decreased spinal flexibility over time

Peripheral and extra-articular symptoms may also occur:

• Enthesitis (pain at tendon/ligament insertion sites)

• Arthritis in hips, shoulders, or knees

• Uveitis (eye inflammation)

• Psoriasis

• Inflammatory bowel disease (IBD)

• Fatigue

Diagnosis

Diagnosis of axSpA is based on a combination of clinical symptoms, imaging studies, and laboratory tests. It often requires the expertise of a rheumatologist.

Diagnostic criteria and tests include:

• Medical history and physical exam: Chronic back pain with inflammatory characteristics

• Imaging:

  • MRI: Detects active inflammation in sacroiliac joints before structural changes occur

  • X-ray: Used to detect sacroiliitis and structural damage in radiographic axSpA

• HLA-B27 testing: Positive in most patients but not required for diagnosis

• Blood tests: May show elevated inflammatory markers (CRP, ESR)

Treatment

There is no cure for axSpA, but treatment focuses on reducing symptoms, controlling inflammation, and maintaining spinal mobility and function.

First-line treatment:

• Non-steroidal anti-inflammatory drugs (NSAIDs): First-line for reducing pain and inflammation (e.g., naproxen, ibuprofen)

Second-line treatment (if NSAIDs are ineffective):

• Biologic therapies:

  • TNF inhibitors: Such as adalimumab, etanercept, or infliximab

  • IL-17 inhibitors: Such as secukinumab or ixekizumab

Additional therapies:

• Physical therapy and regular exercise to improve posture and spinal flexibility

• Patient education and support programs

• Management of associated conditions (e.g., uveitis, IBD)

Prognosis

The prognosis of axial spondyloarthritis varies by individual and depends on early diagnosis, disease severity, and treatment adherence. With appropriate treatment, most patients can lead active, productive lives.

Prognostic factors:

• Positive outcomes: Early treatment, good response to NSAIDs or biologics, non-radiographic disease

• Worse outcomes: Delayed diagnosis, severe spinal fusion, smoking, and persistent high inflammation

Long-term complications in severe cases may include spinal fusion, disability, or impaired quality of life. Ongoing monitoring and lifestyle modifications can help reduce these risks.