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Researchers have unveiled a prototype device which they claim can spot the onset of osteoarthritis in the knees.

The acoustic device works by scanning the knees for sounds that indicate a deterioration in the knee joint.

The device is being developed by researchers at the universities of Lancaster and Central Lancashire.

Some eight million people in the UK are thought to have osteoarthritis, of which about one million request treatment.

"We wanted to see whether we could listen to moving joints and use the patterns of sound that are emitted to tell us something about whether the joint is changing," explained Prof John Goodacre of Lancaster University.

"Essentially we have set up a way of measuring the sound coming from joints based upon a simple repetitive movement of sitting to standing.

"We collect that sound and analyse it in various ways to look at the amount of sound but also the characteristic of the sound and that seems to be giving us a good idea of whether the joint is affected by osteoarthritis."

When osteoarthritis develops in the knee, the cartilage which covers the ends of the bones in the knee joint is damaged. It can become so worn out that bone can be left rubbing directly on bone causing immense pain to the sufferer.

Currently, there are no cures for the condition, but weight loss can reduce the pressure on the joint, while moderate exercise can prevent stiffness. In extreme cases, surgery can be considered.

Spotting the condition early, said Prof Goodacre, could be key.

"If we can actually pick the changes up earlier or if we can show reliably that changes are occurring even before symptoms, then that would lay the way open to a whole variety of approaches.

"Some would be around lifestyle management... some might be around medication and other such treatments."

The inspiration for the device comes from industry where acoustic tools are already in use to spot wear and tear. For example, in ports, such devices are used to spot damage to the bearings in jetty loading arms, which pump oil and other liquids from ships.

What works for worn-out bearings might not necessarily work for an arthritic knee and much work and clinical testing remains to be done.

But Prof Goodacre is hopeful that the device can be developed into a cheap and practical tool for GP surgeries and clinics which would be used to diagnose and monitor osteoarthritis.

"We imagine that it would be a piece of a portable equipment a bit like an ECG machine. This could be used by the doctor or the nurse to make a regular assessment of change within the knee joint."

Jane Tadman, a spokeswoman for Arthritis Research UK, which is funding the project, said any tool that could help doctors and patients to better manage the condition, would be welcome.

"Despite its high prevalence there is no effective drug treatment to control the progression of osteoarthritis, and currently available painkillers carry a high risk of side effects.

"We know however that a combination of exercise, self-management techniques and active coping skills can be helpful, and the sooner people find out about the condition, the quicker we can help people to help themselves."