Ankylosing spondylitis Dr Rob Hicks Ankylosing spondylitis (AS) is a condition where the spine becomes inflamed and stiff, causing it to lose its normal shape. Sometimes it affects other joints in the body, such as the hips, knees and ankles.

In this article

What causes it? What are the symptoms?

Who's affected? What's the treatment?

No one knows precisely what causes AS, although some people with the condition have an inherited blood type that makes them more likely to be affected.

Tendons or ligaments attached to the spine become swollen. When this subsides, new bone grows that replaces tendons and ligaments. If the continues, the vertebrae (spinal bones) fuse.

AS may cause lower back pain that can spread and be felt in the buttocks and thighs, lower back stiffness. Other symptoms include tiredness, weight loss and a mild fever.

The pain and stiffness are usually worse early in the morning and after resting, but improve with exercise as the day progresses.

Because the spine loses its normal shape, people may find their back becomes bent forwards. This can make walking and moving around painful and difficult.

AS usually starts in the late teens and early 20s. Men are affected more than women.

Prevent further problems by sticking to a healthy weight

It's not possible to prevent AS and there's no cure. However, people with AS can prevent further problems by sticking to a healthy weight, eating a diet rich in calcium, vitamin D and protein, and avoiding contact sports that may damage the joints.

Physiotherapy that includes back and breathing exercises helps to keep the spine and joints strong. Keeping active and taking regular exercise is key to keeping symptoms under control, improving posture and preventing spine deformities.

Paracetamol or anti-inflammatory medication, such as ibuprofen, are used to relieve pain and inflammation. In serious cases, surgery may be needed.

Unlike most inflammatory conditions, many people find their ankylosing spondylitis gets much better as they get older.

This article was last medically reviewed by Dr Rob Hicks in October 2007