Important information about the effectiveness of arthritis drugs will be revealed by a hi-tech scanner developed by doctors.

Osteoarthritis is caused by the gradual degeneration of cartilage - the material which cushions the joints.

When it breaks down, bone can rub on bone, causing painful disability.

Existing x-rays and scans can be confusing to interpret, and may not highlight subtle changes in the amount of cartilage.

A combination of magnetic resonance imaging (MRI) scanning and computer technology allows the Cambridge doctors to view a far more detailed 3D image of the cartilage.

The computer can then measure the exact quantities of different tissue types.

Professor Laurie Hill, of Cambridge University, said: "The rate of change is very slow and just looking at one image and another a year later, it's very hard to see the change, whereas to measure it in a computer we can measure volumes in millilitres and size in millimetres."

Trials of drugs using the new scanning technology are expected to start next year.

Professor Hill Gaston, from Addenbrookes Hospital and Cambridge University, said: "Technology will tell us quicker and more accurately which of the drugs available to us are actually doing the job.

"Measurements which are actually made on the patients are incredible in that type of assessment."

It is estimated that approximately one million people in the UK suffer from osteoarthritis.

There are few effective treatments for the condition, although some sufferers are advised to take as much exercise as possible to keep muscles active.

Some arthritis sufferers try TENS treatment, which uses mild electrical stimulation to ease pain.