what is AS?

Overview

Ankylosing Spondylitis (AS) is an arthritic disorder characterised by chronic inflammation typically affecting the lumbar spine, large peripheral joints and eventually producing generalised severe stiffness and rigidity, involving the ribs and neck. Some 30% of AS patients will also develop eye inflammation in the form of Uveitis. 

AS occurs more frequently in men than in women, with a ratio of 3:1. The great majority of AS patients are HLA-B27 positive and the disease tends to start in the late teens or early twenties.

The onset of the disease is often insidious, and the patient may complain of transient muscular pains, stiffness, tiredness, malaise and fatigue before any joint symptoms appear.

Some patients present with acute episodes of pain involving the buttocks, lumbar spine, ribs and joints such as hips, knees, hands, ankles and toes.

A major feature is “early morning muscle and joint stiffness” whereby the patient finds great difficulty in getting out of bed and often describes that they are so stiff they have to “roll out of bed”. This is almost a diagnostic symptom of the disease.

Eventually the AS patient will have characteristic radiographic changes of the sacroiliitis, when the diagnosis of AS can be confirmed. Furthermore, there is a characteristic inflammation at the point of insertion of tendons or ligaments into the bone at the enthesis, and this is labelled as Enthesitis. After many years the AS patient can develop a characteristic curvature of the spine or kyphosis, caused by fibrosis and calcification of intervertebral joints. These are irreversible changes and the patient will require analgesic drugs to control the pain.