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Plastic bottles can be turned into lighter, cheaper prosthetic limbs

Plastic bottles can be turned into prosthetic limbs which are 40 per cent lighter and thousands of pounds cheaper than existing models, scientists have discovered.

Two patients are now walking with artificial legs whose sockets are made from ground-down plastic that might otherwise have ended up in land-fill.

Researchers at De Montfort University say the new technique enables a more exact fit around the patient’s stump than carbon or glass fibre models, and reduces the risk of infection because of its breathable design.

At £10 a unit, it is also 500 times cheaper than the standard price of £5,000.

Approximately 45,000 people in England rely on prosthetic limbs, with the NHS spending around £60 million a year on care for patients with an amputation or congenital limb deficiency.

Meanwhile estimates suggest that only seven per cent of the roughly one million plastic water bottles bought every minute worldwide are recycled, with the remainder ending up in landfill or polluting the seas.

Dr Karthikeyan Kandan, who has spent most of his career designing materials for bullet-proof vests, said: “Upcycling of recycled plastics and offering affordable prosthesis are two major global issues that we need to tackle.”

He added: “There are some really scary statistics about how much plastic there is polluting our oceans and the planet.

“One of the biggest problems is that the plastic bottles cannot be recycled and reused for the same purpose, so it’s up to us to find new uses for them.”

Artificial limbs have previously been made from bulk plastic - high-density polyethylene - however those were heavy and not durable.

Patients try the new design - Credit: De Montfort University
Patients try the new design Credit: De Montfort University

By contrast, the new design spins recycled polyethylene terephthalate (PET), the building blocks of plastic bottles, into yarns 10 times stronger than bulk plastic.

These yarns can be “knitted” into a porous socket which keeps the patient cooler, particularly crucial in the case of diabetic amputees, who often sweat a lot.

This is a feature that neither carbon or glass fibre sockets - currently the best designs available - can boast.

It takes approximately five one-litre Coca-cola bottles to make one prosthetic socket.

Funded by the Academy of Medical Sciences, the team at De Montfort fitted the PET yarn sock over the moulds of two amputees’ stump.

The manufacturing process was completed by putting the sockets at 230 degrees Celsius for 20 minutes.

They were then flown to Jaipur in India and fitted to the patients, one who had lost his leg above the knee, and one below.

“Both patients were really impressed - they said the prosthetic was lightweight and easy to walk with, and it allowed air to flow to the rest of the leg,” said Dr Kandan.

His group is currently preparing a larger international trial of the new material which would give an evidence base allowing health chiefs to adopt the design for routine use.

Plastic bottles are notoriously difficult to recycle.

Where they are, the PET often goes into lower-quality products like cheap carpets and synthetic football shirts.

In June a Daily Telegraph undercover investigation found showed that under-pressure staff at recycling centres were throwing plastic bottles into the general waste, rather than recycling.

The Telegraph has launched a Zero Waste campaign, calling on the government, local councils and private companies to improve recycling rates and to make the process simpler.