Ankylosing spondylitis (AS) is a type of inflammatory arthritis that causes chronic spine inflammation. AS also is an autoimmune disease, a condition in which the immune system malfunctions and attacks healthy tissues in and around the joints. It often starts in the lower back.

AS also causes sacroiliitis—inflammation of the sacroiliac joints located between the pelvis and the base of the spine. AS can affect other joints throughout the body as well, including the shoulders, neck, hips, hands, feet, and heels. If AS becomes severe, it can lead to a hunched back and other spinal deformities.

There is no cure for AS, but the condition is treatable. Early diagnosis and treatment can reduce the risk of spinal damage, disability, and other disease complications.

This article will cover the early signs and symptoms of AS, diagnosis, causes, and treatment.

Early Signs and Symptoms of AS

AS mainly causes pain and swelling of the low-back joints where the spine meets the pelvis. The earliest signs of AS are in the back and hips. Stiffness and pain are common in the morning and after being inactive. Some people with AS might also experience neck pain and fatigue.

Initially, symptoms of AS will be subtle or last for short periods. But over time, they worsen. They might also improve and stop, especially very early in the disease process. AS back pain and stiffness often improve with activity.

Additional early symptoms of AS are:

• Pain in the buttocks
• Inflammation of the sacroiliac joints
• Pain, swelling, redness, and warmth in other joints, including the ribs, knees, ankles, shoulders, neck, and the smalls joints of the hands and feet
• Back pain that wakes you up at night
• Back pain that lasts 30 or more minutes after waking up
• Fatigue
• Appetite loss
• Mild fevers
• Pain and tenderness at the entheses (the areas where ligaments and tendons attach to bone)
  
• Eye inflammation: Pain, redness, and/or swelling of one or both eyes, light sensitivity, or blurred vision
  

Ankylosing Spondylitis Diagnosis

There aren't any definitive testing methods that can confirm an AS diagnosis. This means your healthcare provider will rely on different diagnostic methods to determine the cause of your symptoms.

If your primary healthcare provider suspects AS, they might suggest you see a rheumatologist. This is a doctor who specializes in diagnosing and treating arthritis, musculoskeletal conditions, and systemic autoimmune diseases.

A diagnosis of AS typically starts with a physical exam. Your healthcare provider might ask you to bend your back in different directions to check for stiffness and pain. They might also push on some body parts to look for tenderness or ask you to take deep breaths.

Your healthcare provider will also want to know about your medical and family histories. They might ask about:

• When pain and other symptoms began
• How long your symptoms last
• What improves symptoms
• What time of the day you experience symptoms
• If family members have been diagnosed with AS or other autoimmune diseases

In addition to a physical exam and your medical and family histories, your healthcare provider will request blood work and imaging studies.

Blood work: Blood work can look for the presence of the HLA-B27 gene, which increases the risk for AS. According to a 2018 report in the journal Clinical Medicine Insights: Arthritis and Musculoskeletal Disorders, up to 90% of people with AS will have a positive HLA-B27 blood test.

Imaging: Imaging helps diagnose AS, determine the extent of the disease, and monitor spine and bone changes. Imaging methods used in AS include computed tomography (CT) scans, ultrasound, and magnetic resonance imaging (MRI).

The diagnostic criteria your healthcare provider will rely on to diagnose AS were established Assessment of SpondyloArthritis International Society (ASAS) in 2009.

According to ASAS's standards, your healthcare provider can make a diagnosis of AS if you are under 45 years of age and have had low back pain or stiffness for three or more months, along with one or more of the following:

• Radiological evidence of sacroiliitis, which includes acute or active inflammation, and sacroiliitis that is grade 2 or higher on both sides or grade 3 or 4 on one side
• A positive HLA-B27 gene test, along with two or more clinical features of AS, such as inflammatory back pain, eye inflammation, arthritis, psoriasis (a chronic inflammatory skin condition), dactylitis (severe swelling of the fingers or toes), and a family history of AS
  

Ankylosing Spondylitis Causes

Anyone can get AS, but certain factors might increase a person's risk for the disease. These include:

• Family and genetics: If a member of your family has AS or another autoimmune disease, you are more likely to get the disease. About 90% of people with AS have the mutated gene HLA-B27. Having this mutated gene increases your risk, but it is possible to have an HLA-B27 mutated gene and never get AS.
• Age: Most people who get AS have symptoms in middle age and before age 45. However, you can be diagnosed with AS in childhood or as a teen.
• Sex: Males are more likely to have AS. The research shows that the disease burden in females is much higher due to diagnostic delays, higher disease activity, and reduced responsiveness to some biologic drug therapies.
• Other autoimmune diseases: If you have another autoimmune disease, like psoriasis or ulcerative colitis (an inflammatory bowel disease), your risk for AS is higher.

Treatment  

AS is a lifelong condition, and you will need treatment for if for the rest of your life. While there is no cure, treatment reduces the potential for joint damage and disability, eases pain, prevents complications, and improves your quality of life.

Treatments for AS include physical therapy, medications, and surgery.

Physical Therapy

Physical therapy can provide a number of benefits for people with AS, including pain relief and improved flexibility and strength. A physical therapist can teach you proper exercise techniques, managing posture, and proper sleeping and walking positions.

Medications

The most common medications used to treat AS are nonsteroidal anti-inflammatory drugs (NSAIDs), conventional and biologic disease-modifying antirheumatic drugs (DMARDs), and corticosteroids, which help in the following ways:

• NSAIDs: NSAIDs, like Advil (ibuprofen) and Aleve (naproxen), can help to ease pain and inflammation. They are available over the counter, but your healthcare provider can prescribe stronger NSAIDs if needed.
• DMARDs: DMARDs like Trexall (methotrexate) and Azulfidine (sulfasalazine) can reduce pain and joint swelling in AS.
• Biologics: Biologics are a newer type of DMARD that help control inflammation by changing how the immune system reacts.
• Corticosteroids: Injectable and oral corticosteroids work to bring down inflammation and ease joint pain.

Surgery

Most people with AS will never need surgery. Your rheumatologist might recommend surgery if you have severe pain or a severely damaged joint. Spinal surgery can correct a curved spine.

Summary  

Ankylosing spondylitis is a type of inflammatory arthritis that causes inflammation of the joints of the spine. AS can sometimes affect other joints, including the hips. Severe or untreated AS can lead to a rigid and inflexible spine.

Early symptoms of AS include pain and swelling of the joints of the low back where the spine meets the pelvis, severe fatigue, buttock pain, neck pain, back pain, and pain and swelling at entheses.

Early diagnosis and treatment are vital to preventing disease complications. AS is treatable with physical therapy, medications, and surgery.

A Word From Verywell

Ankylosing spondylitis is a lifelong condition, but most people with AS can live normal and productive lives. Some people may experience a severe, crippling form of AS, but that probably won't be the case for you. Due to newer, more advanced medicines, very few people become severely disabled from AS.

Keep in mind that people will respond to medications differently—what works for someone else might not work for you. Choose to be patient and participate in your healthcare. While there is no cure for AS, there is a lot you can do to manage its effects.