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Last Updated: Monday, 3 July 2006, 10:45 GMT 11:45 UK
'Bionic' limb breakthrough made
Patient with implant (Norbert Kang)
A metal rod protrudes through the skin
UK scientists have developed technology that enables artificial limbs to be directly attached to a human skeleton.

The breakthrough, developed by researchers at University College London, allows the prosthesis to breach the skin without risk of infection.

The team says early clinical trials have been "very promising".

It hopes the work - which is to be published in the Journal of Anatomy - may help survivors of the 7 July bombings, as well as other amputees.

The work paves the way for bionic limbs which are controlled by the central nervous system.

In the deer antlers it is very much to do with the structure and shape of the bone, and the porosity of the bone
Dr Paul Unwin
The technique, called Intraosseous Transcutaneous Amputation Prosthesis (ITAP), involves securing a titanium rod directly into the bone.

The metal implant passes through the skin and the artificial limb can be directly attached to it.

Currently, artificial limbs are fixed or strapped to an amputee's stump.

Risk of infection, which could be caused by bacteria passing from the external limb through the rod to the bone, is avoided because the skin tissue meshes around the rod to form a seal.

Deer antlers

To work out how to attach live tissue directly to metal, the scientists from the Centre for Biomedical Engineering, UCL, led by Professor Gordon Blunn and Dr Catherine Pendegrass, looked at how deers' antlers can grow through the animals' skin without infection.

Metal implant (C Pendegrass)
The scientists based their design on the bone in a deer's antlers

Dr Paul Unwin, managing director of Stanmore Implants Worldwide, a medical devices company that worked in collaboration with the scientists, said: "The mobility of tissue is a big factor; you don't want the tissue to rip away from the piece of metal, so you need a structure under the skin that will allow the dermal tissues to attach into the metal.

"What we had seen in the deer antlers was that it is very much to do with the structure and shape of the bone, and the porosity of the bone.

"The tissue attaches in with long fibres, and it is like anchors attaching directly into it."

He said that early clinical trials, which had taken place at Mount Vernon Hospital, Middlesex, on a small group of patients who had lost fingers or thumbs had been very encouraging.

The next stage, he added, would be to carry out trials on upper and lower limb replacements.

He said he expected victims of last year's London bombing attacks who lost limbs to be involved.

He said that the technology could be widely used for thumb and forefingers in a few years, and upper and lower limb replacements using this method could be in place in five years.

Zafar Khan, chairman of the Limbless Association, said: "As an amputee, residual limbs are currently inserted into a socket, to which a prosthetic limb is attached.

"And when you walk or use the limb there is a movement and that causes rubbing and pressure sores. The real benefit is that would not happen with this new technique.

"But on the downside, I would still be worried about infection."


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