Bone-scan discovery raises hope on arthritis: New test likely to help sufferers

FOR THE first time, doctors are able to tell when arthritis, which affects one in ten people, is going to cause severe damage to a patient's joints.

The discovery that bone- scanning techniques - normally used to help diagnose cancer - can be used to predict the destruction of a joint by osteoarthritis, comes at the right time for researchers, an expert said yesterday.

Professor Paul Dieppe, a rheumatologist at the University of Bristol, said the test enabled doctors to see if any of the new range of experimental treatments for arthritis was working.

The problem with a long- term, slow disease that can develop over 20 years, is that it is hard to evaluate the effectiveness of new approaches.

He said yesterday: ''New therapies can now be targeted at the high-risk group. For the first time, we can see the disease; we have never had a handle on it like this before.

'Doctors in all levels of medicine can now take an optimistic approach. With X- rays we could only see both new and old damage; they gave us only a historical record; we could not see if the disease was active.'

Bone scanning involves injecting a 'bone-seeking' chemical with a mildly radioactive agent into the blood stream. Images from a gamma camera will then show the arthritic 'hot spots'.

Professor Dieppe said it was still not properly understood why scanning picks up active disease and not the damage that has already been done, but after a five-year study of 100 patients doctors were now confident that the technique could accurately predict active disease.

'Osteoarthritis was seen as a slow disease that took 10 to 20 years to 'go bad'. It started when you were about 50 and slowly deteriorated and there was nothing you could do. Clinically it has been a very difficult disease to study because of its slow process. Now we have a means of seeing if treatments are working.'

Osteoarthritis affects about 5 million people over 45 years old. It is the commonest form of the disease; fingers and knees are most commonly

affected.

Professor Dieppe said that joint replacement surgery as the only response to arthritis was 'crazy'. 'It makes no sense to do nothing to help until it is so bad that all you can do is replace the joints.'

However, the bone-scanning technique should not be used more than two or three times on any one patient, Professor Dieppe said, since it involved radioactive material.

Now that doctors know it is possible to predict the course of the disease, they are looking at other means of scanning - by adapting magnetic resonance imaging (MRI) to pick up active bone and cartilage disease - and developing a blood test.

New forms of treatment being researched include the development of chemicals which inhibit the enzymes that destroy cartilage; injecting into joints cushions of biological polymers; and exercise to strengthen muscle around affected joints.