Ankylosing Spondylitis - What Is It?

Ankylosing spondylitis (AS) is a form of inflammatory arthritis. It mainly affects the spine, but can also affect other joints, tendons and ligaments.

The sacro iliac joints are located in the low back where the sacrum (the bone directly above the tailbone) meets the iliac bones (bones on either side of the upper buttocks). Chronic inflammation in these areas causes pain and stiffness in and around the spine. Over time, chronic spinal inflammation (spondylitis) can lead to a complete cementing together (fusion) of the vertebrae, a process referred to as ankylosis. Ankylosis leads to loss of mobility of the spine.

AS can cause inflammation anywhere within the body. AS can sometimes affect the eyes, bowel, heart or lungs.

Entire fusing of the spine is unusual. Many people will only have partial fusion, somethimes limited to the pelvic bones. If the spine and its supporting structures stiffen do start to fuse or grow together, people can develop an extremely stiff, rigid backbone called a bamboo spine. The pain and rigidity in the lower back can cause problems walking. Almost any movement can become extremely painful.

AS: -

• Affects approximately 2-5 adults per 1,000 in the UK. This means that an estimated 200,000 people in the UK have AS.
• We know there is a strong association between AS and a gene called HLA B27. In white western Europeans around 8% carry this gene. Although HLA B27 is present in over 95% of people with AS, only about 1 in 15 people who are HLA B27 positive go on to develop AS. This means that this gene alone is not responsible for people developing AS but must contribute towards it.
• It usually begins in early adult life with the average age of diagnosis being 24.

AS is a very variable condition. Some people with AS have virtually no symptoms whereas others suffer more severely. it is a lifelong condition.

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