The sugar-crazed seven-year-olds stopped their manic game of Jedi Knights and watched me in astonishment. While most mums and dads at this children’s party were relaxing on garden chairs sipping wine, I was performing cartwheels across the lawn. “She does this a lot,” I heard my husband say to one of the bemused parents. “She has a back problem.”
If I sit or stand for a while I get a dull ache down my spine that goes only by doing something strenuous. Stretching is actually best; but cartwheels are just more fun. I suffer from ankylosing spondylitis, a progressive, incurable, inflammatory disease that causes joints, particularly the spine, to fuse. It can lead to complete fusion of the vertebrae, hence its more evocative name “ bamboo spine”.

Fortunately for sufferers (estimated by the National Ankylosing Spondilitis Society at 1 man in 200 and 1 woman in 500), complete fusion is rare. Most, like me, suffer pain and discomfort but manage to lead active, if not very active, lives mainly to prevent it worsening.

My condition was diagnosed 12 years ago and changed my sedentary lifestyle dramatically. I now do stretching exercises daily, swim three times a week and spend as little time as possible at a desk. Running around after our two small children, Eve and Max, helps.

But, as with many people with ankylosing spondylitis, I had symptoms for ten years before doctors found the cause. I can now trace my earliest symptoms to when I was 18. I developed an ache in my hip, which radiated down my leg. I was told that it was caused by too much disco-dancing.

Throughout my twenties the pain shifted to my neck then to my upper back, to legs again and to the lumbar spine. I would be woken by a dull ache somewhere in my body, alleviated only by moving around and having a hot bath. I didn’t look for a different diagnosis because doctors repeatedly prescribed anti-inflammatory pills and told me to “take it easy”.

I wasn’t until I was 31 and developed iritis — an inflammation of the iris often linked to ankylosing spondylitis — that a more thorough investigation was suggested by an eye doctor. A blood test showed that I had the blood antigen HLA-B27, found in some 95 per cent of sufferers. This didn’t in itself mean I had ankylosing spondylitis, but an X-ray, showing partial fusion of one of my pelvic (sacro-iliac) joints, did.

The news was a shock. As a journalist, I had just interviewed someone only a couple of years older than me who had the condition. He had an old man’s stoop and was unable to work. The prospect of deformity and unemployment scared me so much that I cried in the hospital waiting room.

My first appointment with a rheumatologist reassured me that the outlook need not be so gloomy. Although my neck clicked and creaked and the fusion in my joint meant that I couldn’t bend fully sideways, the rest of my mobility was good. I was signed up for physiotherapy, where I was taught stretches and yoga poses, and told to exercise daily.

For about 18 months after the birth of Eve seven years ago, I took the prescribed non-steroidal anti-inflammatory drug (NSAID) diclofenac as the strain of carrying around a small child exacerbated my aches. The symptoms returned during my second pregnancy with our son Max four years ago. As I couldn’t take NSAIDs while pregnant, I had to step up the exercise.

Now my mobility seems better than before. The exercise may have staved off the worst effects, or maybe I have a mild version. My rheumatologist says that as you get older, the disease burns itself out. So some day I may be free of pain — something to look forward to.

What is ankylosing spondylitis?

An arthritic condition. Some people seem to have a genetic susceptibility which is triggered by some environmental factor — possibly a bowel infection.

What are the symptoms? Gradual onset of back pain and stiffness. Pain reduces with exercise. Weight loss, especially in early stages.

What happens to the joints? Inflammation where tendons attach to bone, usually in the spine, but also in knees, ankles and heels, followed by erosion of bone at site of attachment. As inflammation subsides, new bone develops replacing the elastic tendon tissue, restricting movement.

Is it different in men and women? There is evidence that men tend to get more back pain, while women suffer more peripheral joint pain.

Is there a cure? No, but NSAIDS (non-steroidal anti- inflammatory drugs) reduce pain, and exercise prevents stiffness. New anti-TNF drugs are now being prescribed and producing results.

Contact the National Ankylosing Spondylitis Society, 01435 873527; www.nass@nass.co.uk; or the Arthritis Research Campaign, 0870 8505000, www.info@arc.org.uk