Prosthetics from plastic

DPA

Every year thousands of people lose arms and legs after being injured by bombs or land mines, but with an estimated 80 per cent of disabled people living in developing countries, few can afford prosthetic limbs.
A German computer scientist has an idea that could change that — he wants to use 3D printing technology to produce cheap, tailor-made limbs for people, based on measurements that can be taken by doctors with their smartphones on location.
The other innovation is that the raw material for the sockets of the artificial limbs would be provided by shredding and recycling old plastic cups. “My challenge is always to get the best possible result from cheap technology and materials as possible,” says 34-year-old Christian Zagel.
He has led a feasibility study at the University of Erlangen-Nuremberg for the past year and a half. The team’s aim is to find out if and how such prosthetics could benefit people in developing countries. The basic idea is that a doctor should be able to measure a stump using just a smartphone. That means circling the patient and taking 20 to 30 photos which slightly overlap.
Software then works out the exact measurements to create a 3D model of the sleeve to fit over the stump. Every prosthetic has to be individualized, otherwise the socket can rub painfully. Bagel got the idea after working with a 3D body scanner, which can for example, enable consumers to test whether a T-shirt from an online shop will fit them.
“If you’ve got the measurements of a human body, it’s not a big leap to think you can use them for other things,” says Zagel. The whole system should be so easy to use that people don’t need any special prior knowledge, he adds.
To make sure that’s the case, researchers at the University of Applied Sciences in Luebeck, northern Germany, are testing the idea’s user friendliness. It only takes one or two minutes to scan a stump, according to Zagel.
Then the prosthetic can be 3D printed and lined with silicone to make it more comfortable. “We’re using the cheapest technology to print,” says Zagel — his machine costs 4,500 euros (5,025 dollars). The socket is printed by layering the material up over a 30-hour period. The rest of the limb, of standard metal parts, is then attached.
The researchers are testing different socket materials for strength and durability; a grown man will need his limb to cope with a fair amount of wear, says Zagel, but at the same time it can’t be too heavy.
“For this technology though, there was no previous data,” he says. Another problem is that “3D printing technology hasn’t fully developed in this price category,” and there have been lots of printing errors. The machines are also sensitive; temperature and air pressure have to be kept constant.
There are also hurdles pertaining to the second of the project’s innovations, the use of disposed plastic containers from retail food. 3D printing material, known as filament, is expensive to buy, with a reel costing around 15 to 20 euros a kilogram.
That’s why Zagel came up with the idea of using compostable plastic cups made of polylactic acid (PLA), which could be chopped up and then further processed before being used for printing.
But finding a shredder and an “extruder” — in which the plastic is melted and then shaped into a wire-form for use in the printer — was difficult, as these machines are usually only produced in large sizes for factories.
Nevertheless Zagel intends to try out his first prosthetics this year and wants the first patients to receive their artificial limbs next year. At the moment however they need more investors; Zagel has plans to use crowdfunding to get more money for the project. He hopes that one day his prosthetics will only cost about 10 euros (11 dollars) per leg.
He and his team aren’t the only ones to try printing artificial limbs, with land mine action charity Handicap International (HI) also looking into it. Jerome Canicave, the organization’s project manager for orthopaedic technology, says the advantages are obvious.
The ability to scan patients using smartphones and the computer-supported design of the limbs would make supplying people in war zones and developing countries significantly easier. It could even mean a paradigm shift in the treatment of people missing limbs, meaning that many more could be treated properly, he says.
“Instead of getting people to come to rehabilitation centres, specialists could scan the stumps and send the data to 3D designers and printing technicians,” says Canicave. The simplest prosthetics currently in use cost around 150 euros.
HI is now running a pilot study on the idea in Togo, Madagascar and Syria with experts in physiotherapy, as well as scientists and companies specializing in 3D printing. A company in Europe is doing the printing. That means there are still transportation costs, but Canicave is confident that soon 3D printers will also be available in developing countries which will reduce costs.