Ankylosing spondylitis (AS) is a condition that mainly affects the spine. The joints of the neck, back and pelvis become inflamed, causing pain and stiffness. The sacroiliac joints are commonly affected in AS. These joints connect the base of your spine (sacrum) to your pelvis. Other joints, such as the hips and shoulders, can also be involved. AS can also affect other parts of the body, such as the eyes, skin, bowel and lungs. The symptoms of AS usually begin between the ages of 15 and 45 years.
What are the symptoms?
The symptoms of AS vary from person to person. The most common are:
pain and stiffness in the back, buttocks or neck
symptoms worse after rest (for example, in the early morning) and relieved with exercise
pain in tendons (which connect muscles to bones) and ligaments (which connect bones to each other), often felt as pain at the front of the chest, back of the heel or underneath the foot.
What causes it?
It is not known what causes AS. Unlike other types of back pain, AS isn't caused by particular jobs, activities or injuries. You are more likely to get AS if you have a history of it in your family. There is a gene called HLA-B27 that is associated with AS. Almost nine out of ten people with AS test positive for this gene. However HLA-B27 is present in 8% of the general population, including healthy people without AS. Recently, two new genes (IL23R and ARTS1) have also been found to be associated with ankylosing spondylitis.
How is it diagnosed?
Many people in the early stages of AS think they have common back pain and do not seek help. However it is important to have AS diagnosed as early as possible as there are many effectivetreatments available. Your doctor will diagnose AS from your symptoms, a physical examination and blood tests to measure levels of inflammation. Your doctor may also order x-rays of your spine, but these tests can all be normal in the early stages. If your doctor suspects you have AS you should be referred to a rheumatologist, a doctor who specialises in arthritis.
What will happen to me?
With the right treatment, most people with AS can lead full and active lives. Many people find there are times when their symptoms worsen (known as a 'flare'), and times when their symptoms get better. In most cases AS can be well controlled with treatment and the pain improves over time. However some people may have severe, long lasting pain. As a result of the inflammation in the spine, new bone may grow around the joints. This leads to permanent stiffness in the back or neck of some people with AS. In severe cases this extra bone can fuse the bones in the spine together, stopping the spine from moving. Fusion of the spine can lead to a bent or forward stooped posture. This used to be common but can now usually be prevented by starting proper treatment as early as possible.
