Spondyloarthritis – Causes, Symptoms and Treatments

Spondyloarthritis (SpA) is a group of inflammatory diseases that primarily affects the bones and joints of the spine, though it can also cause pain and swelling in other joints and areas where ligaments and tendons attach to bones. Other forms of arthritis, such as rheumatoid arthritis, typically affect peripheral joints (wrists, fingers and feet), whereas SpA often affects joints in the spine and pelvis. 

Types of spondyloarthritis

The term SpA is an umbrella term for several related conditions. The main classifications are axial spondyloarthritis (axSpA) and peripheral spondyloarthritis (pSpA), though some forms can affect both areas. 

Axial spondyloarthritis (axSpA)

This type primarily involves the spine and sacroiliac (SI) joints, which connect the pelvis and lower spine. AxSpA is further divided into two types: 

• Ankylosing spondylitis (AS): The more advanced form of axSpA, in which inflammation has caused visible joint damage and fusion of the vertebrae (the bones of the spine) that can be seen on X-rays.
• Non-radiographic axial spondyloarthritis (nr-axSpA): An earlier stage of the disease where symptoms are present, but there is no visible joint damage on X-rays. Some people with nr-axSpA will eventually develop AS. 

Peripheral spondyloarthritis (pSpA)

This type causes inflammation in the joints and tendons outside the spine, such as those in the hands, feet, wrists, elbows, knees, and ankles. Specific conditions include: 

• Psoriatic arthritis (PsA): An inflammatory condition that develops in people who also have the skin condition known as psoriasis.
• Reactive arthritis: Triggered by an infection in the urinary tract, genitals, or intestines.
• Enteropathic arthritis: Associated with inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis.
• Undifferentiated spondyloarthritis: Occurs when a person has SpA symptoms that do not fit into any other specific category. 

Ankylosing spondylitis

Ankylosing spondylitis (AS), also known as radiographic axSpA, is an advanced form of Axial spondyloarthritis (axSpA), in which inflammation causes visible joint damage and fusion of the bones of the spine (vertebrae) that can be detectable on X-rays. Nonradiographic axSpA (nr-axSpA) causes damage that may not be visible in X-rays but it may be detected with magnetic resonance images (MRIs). Both of these diseases are members of the group known as Spondyloarthritis (SpA).

Who gets spondyloarthritis (SpA)?

In most cases of SpA, the symptoms start to show up in young adults, often when they’re still in school or just starting families and careers. There was a theory that men outnumbered women by three to one, but it has more recently been proven that women are underdiagnosed, especially when the bone damage doesn’t show up on X-rays. Newer research suggests SpA is an equal opportunity offender, striking men and women equally. Black Americans are less likely to have AS than whites but tend to have more severe disease.

Symptoms of ankylosing spondylitis

Symptoms can vary depending on the specific type of SpA but often include: 

• Chronic pain and stiffness: Typically in the lower back and hips, particularly in the morning or after periods of inactivity. This often improves with movement.
• Fatigue: A common symptom due to the body’s inflammatory process.
• Enthesitis: Inflammation at the sites where tendons and ligaments attach to bone, most commonly causing pain in the heel, foot, or rib cage.
• Dactylitis: Swelling of an entire finger or toe.
• Eye inflammation (uveitis/iritis): Characterized by eye pain, redness, and sensitivity to light.
• Skin rash (psoriasis): May be present in psoriatic arthritis.
• Bowel inflammation: May occur in enteropathic arthritis. 

Causes and risk factors

The exact cause is unknown, but genetics seems to  play a significant role. The HLA-B27 gene on chromosome 6 is strongly associated with SpA, particularly in its axial forms, although not everyone with this mutation develops the condition.

Risk factors include: 

• Genetics: A family history of spinal arthritis or related conditions. More than 80% of people who have axSpA carry the HLA-B27 gene mutation, but the reverse is not true – most people with the gene never get arthritis.
• The presence of other related conditions, such as psoriasis or IBD (inflammatory bowel disease.)
• Certain bacterial infections (STDs like Chlamydia trachomatis, or  salmonella, shigella, yersinia, and campylobacter) can trigger reactive arthritis. 

Diagnosis of AS

Because symptoms can resemble those of other conditions, diagnosing AS and nr-axSpA is challenging. There are no current diagnostic criteria for axSpA. There have been no updates to the definition (called the New York criteria), since 1966. The New York criteria depend almost entirely on X-ray findings, but X-rays – even MRIs – aren’t always definitive, nor can they always be interpreted accurately. The lack of reliable diagnostic criteria may make it easier to mistake ordinary back pain for nr-axSpA, leading to unnecessary treatment. 

A specialist healthcare practitioner (rheumatologist) should be the one to conduct a comprehensive evaluation that includes: 

• Physical exam: Assessing the spine’s range of motion and checking for tenderness in affected joints.
• Medical history: Including family history and a detailed discussion of symptoms.
• Imaging tests: X-rays can show joint damage in later stages, while magnetic resonance imaging (MRI) can detect early inflammation not yet visible on X-rays.
• Blood tests: To check for markers of inflammation and the HLA-B27 gene. 

Treatment options for SpA

While there is no cure for SpA, treatments can effectively manage symptoms and slow disease progression. A treatment plan is tailored to the individual and depends on the specific type and severity of the condition. 

Medications:

• • NSAIDs: Nonsteroidal anti-inflammatory drugs are often the first-line treatment for pain and inflammation. NSAIDs are called COX inhibitors that work by blocking one of two enzymes (called COX-1 and COX-2) that create chemicals known as prostaglandins, which trigger pain and swelling. By lowering prostaglandin levels, NSAIDs reduce inflammation and pain in muscles and joints, making it easier for a person to move, sleep, and recover. For many people with AS or nr-axSpA, these drugs along with exercise are enough to control symptoms. 
    • Naproxen
    • Neurofen
    • Celebrex
    • Arcoxia
    • Cataflam

     

  • DMARDs: Disease-modifying antirheumatic drugs, such as sulfasalazine, are used for peripheral arthritis.
    • JAK-inhibitors
      • Xeljanz (FDA-approved)
      • Olumiant (off-label when TNF blockers did not work well or could not be tolerated.)
      • Rinvoq (FDA-approved)

• • IL-6 Inhibitors/Monoclonal antibodies

• • • Kevzara
    • Skyrizi

     

  • Biologics: These advanced drugs target specific inflammatory pathways and are used for severe cases, especially those affecting the spine.
    • Cimzia (TNF inhibitor – FDA-approved)
    • Humira (TNF inhibitor – off-label)
    • Remicade (TNF inhibitor – off-label)
    • Cosentyx (IL-17 blocker – off-label)
    • Taltz (IL-17 blocker – off-label)

• • Corticosteroid injections can be used to treat localized joint swelling or inflammation. 

Lifestyle changes

Some simple lifestyle changes can both ease the symptoms and slow down the pogresss of the disease

• Smoking worsens AS – quitting smoking is important when you have AS or nr-axSpA. 
• Switching to an anti-inflammatory diet like the Mediterranean diet which has been shown to help reduce arthritis symptoms in individuals dealing with different types of arthritis.

Frequently asked questions about Spondyloarthritis

Is ankylosing spondylitis considered a permanent disability?

Ankylosing spondylitis (AS) can be disabling for some people, but it is not always a permanent disability. In the United States, eligibility for disability benefits depends on how much AS limits daily function and work. The Social Security Administration may approve benefits if medical evidence shows severe, lasting limitations. Learn more from Medical News Today and the SSA listings via SSA.

Which is worse, rheumatoid arthritis or ankylosing spondylitis?

Neither disease is universally “worse.” They affect different areas and progress differently. Rheumatoid arthritis usually targets peripheral joints like hands and feet, while AS mainly involves the spine and sacroiliac joints. Both can be serious without treatment, and outcomes depend on severity and response to therapy. See overviews from MedlinePlus (AS) and NIAMS (RA) for context.

What is the most common age for ankylosing spondylitis?

Symptoms often begin in early adulthood, typically before age 45, with many first noticing back pain and stiffness between ages 20 and 40. Juvenile cases can occur, but are less common. References: NIAMS and an overview on age of onset from NHS.

What are the three tests to tell you if your back pain is caused by spondyloarthritis?

No single test confirms AS. Clinicians combine: 1) imaging (sacroiliac joint and spine X‑rays; MRI detects earlier inflammation), 2) blood work for HLA‑B27 and inflammatory markers, and 3) a clinical exam and history focused on inflammatory back pain features. See Cleveland Clinic and NIAMS.

Which foods should be avoided in ankylosing spondylitis?

Evidence on specific “avoid” lists is limited, but many experts suggest limiting ultra‑processed foods, added sugars, and high‑sodium or high‑fat items, which can worsen general inflammation and heart risk. Some people find trigger foods individually. A Mediterranean‑style pattern is often encouraged. Read more at Healthline and general diet guidance via NIAMS.

Which foods should be avoided in ankylosing spondylitis?

There isn’t one proven “AS diet.” Consider reducing refined carbs, sugary drinks, processed meats, and excess alcohol. Focus on whole foods, vegetables, fruits, legumes, whole grains, and omega‑3 sources like fish. Keep a symptom diary to spot personal triggers. See Healthline and general anti‑inflammatory approaches from Arthritis Foundation.

Is spondyloarthritis curable?

AS is a lifelong inflammatory condition. There is no cure, but treatments can control symptoms and slow progression. Options include exercise, NSAIDs, and advanced therapies like TNF or IL‑17 inhibitors in eligible patients. Early diagnosis and consistent care help preserve function. Learn more from the articles at Spondylitis Association of America.

Is ankylosing spondylitis hereditary?

Genetics play a strong role. Many people with AS carry the HLA‑B27 gene, though most HLA‑B27 carriers never develop AS. Family history increases risk but doesn’t guarantee disease. Additional genes and environmental factors are involved. See genetics summaries at NHS and StatPearls.

Can ankylosing spondylitis affect the eyes?

Yes. Uveitis (eye inflammation) can occur, causing eye pain, redness, and light sensitivity. Prompt evaluation by an eye specialist is important to prevent complications. Learn more from MedlinePlus and clinical overviews from Johns Hopkins Arthritis Center.

What’s the difference between inflammatory and mechanical back pain?

Inflammatory back pain from AS often starts before age 45, lasts over three months, improves with movement, and does not improve with rest. Mechanical back pain (e.g., strain or disc issues) typically worsens with activity and eases with rest. Screening prompts appear in the SAA’s quiz: Spondylitis.org, with criteria discussed by NIAMS.