Ankylosing spondylitis
Ankylosing spondylitis (AS) is a type of arthritis that mainly affects the spine, where the joints of the spine and the joints between the spine and pelvis become inflamed. This results in pain and stiffness in the neck and back. Although there is no cure for AS, exercise can help relieve symptoms, and medicines are available to reduce pain.
About ankylosing spondylitis
Ankylosing spondylitis (AS) causes inflammation of the joints of the spine. Spondylitis is the medical term for inflammation of the joints of the spine. Ankylosis is the medical term for the stiffening caused by the inflammation.
AS is not a rare condition. It was once thought to predominate in men but is now thought to be seen as often in women, however, it is generally less severe than in men.
Causes of ankylosing spondylitis
The cause of AS is not known, but the condition may be partly hereditary (passed down from parents to children).
There is a strong association between ankylosing spondylitis and a gene called HLA-B27. It is thought that this causes the body's immune system to attack the joints of the spine, which is what causes the inflammation. Therefore ankylosing spondylitis is often thought of as an autoimmune disease - a disease in which the person's own immune system attacks their body. However, not everyone with the HLA-B27 gene develops ankylosing spondylitis.
The spine
The spine is made up of 24 bones called vertebrae, plus the sacrum and coccyx. These are linked with joints. There are three main sections of vertebral spine: cervical (neck), thoracic (chest) and lumbar (lower back). In the thoracic section, each vertebrae also has joints with 12 pairs of ribs. Below the lumbar spine is the sacrum, which is actually five vertebrae fused into one bone. This forms a joint with the pelvis (hip bone) on either side, called the sacroiliac joint.
Any of these joints in the spine may be affected by AS.
Posture of some people with ankylosing spondylitis
Symptoms
Typically, the symptoms of ankylosing spondylitis come and go. AS often starts at the sacroiliac joint causing lower back pain, which is usually worse at night and in the morning, and relieved by gentle activity. There may also be pain in the buttocks or down the backs of the thighs. Typically, the back is stiff in the mornings.
In up to one quarter of people with AS, other joints are affected. These include the hips, knees and shoulders, and occasionally the smaller joints in the hands and feet. This may cause aching and swelling.
The symptoms of AS vary in different people. Some people may only get a few mild aches and pains, which come and go over a period of a few months. Others get periods of active AS (flare-ups), when symptoms become more severe and widespread. Other symptoms can include:
- loss of appetite
- general feeling of being unwell
- occasional inflammation of the eye (iritis)
When AS has been present for a few months, the back may stiffen, usually in the lower back. This happens when the inflammation reduces and healing takes place. Bone then grows out from both sides of the spine, joining the vertebrae together. Some people may stoop, whereas others develop a straight, stiff spine. In time, the inflammation can lead to permanent stiffness, but as the spine becomes more rigid, the pain may decrease. In some people the disease then disappears.
As the spine becomes more rigid, it is more prone to fractures (breaks).
If the joints where the ribs meet the spine are affected, breathing can become difficult and painful. However, only a minority of people who have ankylosing spondylitis develop a rigid spine and chest.
Associated conditions
Ankylosing spondylitis is one of a group of diseases called spondylarthritides. Others include psoriatic arthritis, colitic arthritis and reactive arthritis. These conditions can occur with AS, or before it. Psoriatic arthritis is joint inflammation associated with psoriasis (a condition which causes patches of inflamed, itchy and flaky skin); colitic arthritis is joint inflammation associated with bowel inflammation; and reactive arthritis is joint inflammation occurring after a bacterial or viral infection.
Rare complications can affect the heart, lungs and nervous system in 1 in 100 people with AS.
Diagnosis
Doctors can often diagnose AS simply from a description of the symptoms and a physical examination. Blood tests are performed to look for signs of inflammation. Blood may also be tested for HLA-B27. If this is present, it shows an increased risk of AS but does not prove the diagnosis.
X-rays are carried out to look for typical changes of AS, such as inflammation of the sacroiliac joints and damage to the joints in the spine.
Treatment
Treatment consists of a long-term programme of physical activity and, when necessary, anti-inflammatory drugs.
During a flare-up, joints stiffen with bed rest. For this reason, people with ankylosing spondylitis are encouraged to remain active. A good form of exercise is swimming, which helps to maintain muscle tone and flexibility.
A specialist physiotherapist can provide more advice. Daily exercises such as spine extension and breathing are often recommended to strengthen muscles and prevent poor posture.
Sleeping on a firm bed with no more than one pillow can help prevent spinal curvature.
Using lumbar (back) supports is not recommended, as they make the stiffness worse.
Medicines
Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen may reduce inflammation and relieve pain. This enables physical activity.
Corticosteroids are occasionally injected into particularly painful joints and used as drops for eye inflammation (iritis).
Surgery
Eventually, surgery may be recommended to replace hip and knee joints that become damaged and painful. Occasionally spinal surgery may be recommended to restore posture.
Further information
Search for "ankylosing spondylitis" on healthinsite.gov.au
The information on this factsheet is intended to be a guide only and is not intended to be nor should be relied on as a substitute for professional medical advice. It is also not intended to be for medical diagnosis or treatment. BUPA Australia makes no warranties or representations regarding the quality, accuracy or completeness of the information. BUPA Australia is not liable to readers of the information for any loss or damage suffered arising out of the use of or reliance on the information, except that which can be excluded by law.