Ankylosing spondylitis is a long-term type of arthritis. It affects the bones and joints at the base of the spine where it connects with the pelvis.

These joints become swollen and inflamed. Over time, the affected spinal bones join together.

Spondylitis; Spondyloarthropathy

The cause of ankylosing spondylitis is unknown. Genes seem to play a role.

The disease most often begins between ages 20 and 40, but it may begin before age 10. It affects more males than females.

The disease starts with low back pain that comes and goes. Low back pain is present most of the time as the condition progresses.

• Pain and stiffness are worse at night, in the morning, or when you are less active. The discomfort may wake you from sleep.
• The pain often gets better with activity or exercise.
• Back pain may begin in the sacroiliac joints (between the pelvis and spine). Over time, it may involve all or part of the spine.
• You may lose flexibility in the lower spine. The condition may affect the joints between your ribs so that you cannot expand your chest fully.

Fatigue is also a common symptom.

Less common symptoms include:

• Swelling of the eye
• Heel pain
• Hip pain and stiffness
• Swelling and pain in the joints of the shoulders, knees, and ankles
• Loss of appetite
• Slight fever
• Weight loss

Tests may include:

• CBC
• ESR (a measure of inflammation)
• HLA-B27 antigen (which detects the gene linked to ankylosing spondylitis)
• X-rays of the spine and pelvis
• MRI of the spine

Your doctor may prescribe nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce swelling and pain.

You may also need stronger medicines to control pain and swelling such as:

• Corticosteroid therapy (such as prednisone)
• Sulfasalazine
• Methotrexate TNF-inhibitors (such as etanercept, adalimumab, infliximab, golimumab)

Surgery may be done if pain or joint damage is severe.

Exercises can help improve posture and breathing. Lying flat on your back at night can help you keep a normal posture.

The course of the disease is hard to predict. Symptoms may come and go at any time. Most people are able to function unless they have a lot of damage to the hips.

Rarely, people may have problems with:

• Abnormal heart rhythm
• Scarring or thickening of the lung tissue
• The aortic heart valve
• Swelling of the eye
• Inflammation in the large intestine (colitis)

Call your health care provider if:

• You have symptoms of ankylosing spondylitis
• You have ankylosing spondylitis and develop new symptoms during treatment

Yu D, Lories R, Inman RD. Pathogenesis of ankylosing spondylitis and reactive arthritis. In: Firestein GS, Budd RC, Gabriel SE, et al, eds. Kelley's Textbook of Rheumatology. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap 74.

Inman RD. The spondyloarthropathies. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011: chap 273.

Sidiropoulos PI, Hatemi G, Song IH, et al. Evidence-based recommendations for the management of ankylosing spondylitis: systematic literature search of the 3E Initiative in Rheumatology involving a broad panel of experts and practising rheumatologists. Rheumatology (Oxford). 2008. 47(3):355-61.