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Last Updated: Wednesday, 9 June, 2004, 10:35 GMT 11:35 UK
Artificial joint 'aids arthritis'

By Chris Hogg
BBC Hong Kong correspondent

Hand model with the metal joint - courtesy of the University of Hong Kong
Researchers have tested the joint in the laboratory
Scientists in Hong Kong say they have invented a new artificial finger joint which could bring relief to millions of arthritis sufferers.

University of Hong Kong researchers have developed a finger implant, made from a metal alloy.

Laboratory tests show it could last for up to 40 years, 10 times longer than existing joints.

Four out of five people with arthritis have problems with their finger joints. Around half require surgery.

The method for locking the alloy joint to the bone is similar to that used to anchor false teeth to the jaw
Professor Chow Shew-ping, University of Hong Kong.
The rest are treated with drugs which can control the pain and reduce inflammation,

Artificial finger joints made of silicon plastic have been used for the last three decades, but tend to fall apart after three years or so.

The new implant, developed at the university is much stronger.

It is made of a cobalt and chrome alloy, the same material used in some artificial hips.

'Proven technology'

"We have successfully developed a new design that has shown a proper anchoring to the bone, a good range of motion and long term performance", says Chow Shew-ping, Professor of Orthopaedics and Traumatology at the University of Hong Kong.

He says that, for years, commercial companies have ignored this area of research believing it wouldn't be that profitable.

But some of the technology used in the new joint is already proven.

Professor Shew-ping said: "The method for locking the alloy joint to the bone is similar to that used to anchor false teeth to the jaw in several Scandinavian countries." professor says.

"And the alloy itself has been shown to work well when used in artificial hips."

The joint has undergone a series of laboratory tests including impact tests and computer simulations to try to estimate how long it might last.

The team of orthopaedic surgeons and bio-engineers at the university predicts that it could last for decades. The next step is to test it in chickens or rabbits.

"Chicken feet are similar to human fingers," says Professor Chow Shew-ping.

"It will be several months, perhaps even a couple of years before we are ready to try it out in humans."

Minimal wear and tear

In Hong Kong, it is estimated up to 30,000 people a year could benefit from finger implants.

A study in 2002 found that more than one in 10 of the population in the former British colony suffers from arthritis or back pain.

Arthritis is a chronic disease which can last up to 30 years.

The researchers say their experiments show that wear and tear on their joint was minimal so they believe it would work for 30 or even 40 years without a problem.

A spokeswoman for medical research charity the Arthritis Research Campaign said: "Currently surgical techniques to replace finger joints are not very successful, and don¿t usually last very long.

"The main challenge is finding a material that is light enough and strong enough to be usable and durable.

"Obviously this research in Hong Kong is still in the early laboratory stages, and it remains to be seen whether a finger replacement made of metal alloy can succeed where other types of materials have failed."

Pain burdens arthritis patients
05 Apr 04  |  Health

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