The cause is not yet known. However, there have been many important discoveries since the early 1970s. One is that about 96% of the estimated 80,000 clinically diagnosed people in this country all share the same genetic cell marker, HLA B27 (Human Leucocyte Antigen B27). This is related to white blood cells and is quite different from red cell groups such as A, B, 0 and rhesus markers.

The average age of onset is twenty-four years old, and the sex distribution is two and a half to three males for every one female.

• Slow or gradual onset of back pain and stiffness over weeks or months, rather than hours or days
• Age of onset in the late teens and twenties, rather than any age; the symptoms can start at other periods of life, but are more likely to have been sparked off by illness or injury (i.e. enforced bed rest)
• Early morning stiffness and pain, wearing off or reducing during the day with exercise
• Persistence for more than three months (rather than coming on in attacks)
• Improvement with exercise and deterioration with rest; the opposite is the case with mechanical back problems.

The diagnosis of AS is confirmed by x-rays. The characteristic changes are in the sacroiliac joints, but they may take many months to develop and may not be obvious during the first consultation. The doctor may also ask for a blood test, which may illustrate how active the disease is. This is called an ESR, and shows the sedimentation rate. Sometimes anaemia can occur.

In some cases, the doctor may ask for the HLA B27 antigen to be tested. If present, the diagnosis could be supported. If HLA B27 is not present, AS is very unlikely but not impossible.

As yet, there is no cure for AS, therefore the emphasis must be on disease management. This is why patient education is so important. Most people with the condition take regular anti-inflammatory drugs to relieve the pain. The person should carry out a regular exercise programme as there is no doubt that not only do these exercises help to maintain mobility and posture of the spine, but they also assist in pain reduction.

Not all people react in the same way to each different type of anti-inflammatory drug. Therefore your doctor might suggest that in time you try a few of them to find the most effective one for you. There are some which can be taken last thing at night to release the drug over a few hours. This will help to maintain pain control over a longer period to assist in a good night's sleep and less morning stiffness.

H e a t
In its various forms heat will help to relieve pain and stiffness. Many people find a hot shower or bath before bed and first thing in the morning will reduce pain and stiffness, especially if some stretching exercises are done at the same time. A hot-water bottle or electric blanket are used by many in bed. Some people also find that cold, when applied to an inflamed area, helps. For instance, a bag of frozen peas wrapped in folded tea towels (take care, as ice can burn).

S u r g e r y
Surgery plays only a small part in the management of this condition. In most cases where surgery is involved it will apply to about 6% of people with AS who will go on to have a hip replaced (arthroplasty). These are very successful and will restore mobility and eliminate pain of the damaged joint. Rarely, surgery is involved in restoring a straighter posture of the spine and neck to people who have become stooped over. These people have difficulty in looking forward and seeing other people's faces, shop signs and door numbers, etc. They will also have difficulty in crossing the road.

C o r s e t s    a n d    b r a c e s
Unfortunately, these are still often prescribed by some doctors not familiar with the modern management of the condition. They very often make matters worse, as they hold the spine rigid. Not moving leads to not being able to move! These are a relic of the past when doctors wrongly thought that it was inevitable that all people with AS would automatically end up with a fused spine. The corsets therefore concentrated on maintaining a straight spine while the stiffening process took place.

A t    w o r k
Pay special attention to the position of your back when at work, trying to avoid stooping. If you sit at a desk or work-bench, pay attention to the height of your seat. Try and move your spine regularly, straighten it out and stretch it by sitting tall and pulling your shoulders back. A job that allows a mixture of sitting, standing and walking is ideal.

A rest is helpful at the end of the working day for those who have a heavy or tiring job. Lying horizontally for twenty minutes is excellent, as it helps to counteract the forward stooping posture of the spine.