Van Phillips, who designed the Flex-Foot Cheetah blades that carried Oscar Pistorius to the Olympics, describes a bad prosthetic limb socket like a stone in your shoe: a nagging discomfort you have to live with until you get the thing adjusted, or replaced.
Many prosthetics wearers live with pain and soreness, either because the socket is badly fitted, or their residual limb changes volume and shape, pushing the socket out of place. According to Jason Hill, co-designer of a new type of prosthetic system, some amputees go through 20 sockets in a lifetime, because the old one no longer fits properly.
The aim of the new concept, called the Beth Project, is to give amputees something more customizable and adjustable. Instead of fabricating the socket in a specialist’s workshop, the socket is shaped with a vacuum pump. The wearer places a silicon bladder over their limb, and then sucks the air out, making it hard like a vacuum-packed bag of coffee.
"We imagine that if their volume has changed over three months, and they are starting to get a sore, they would be able to reshape the surface," Hill says.
The product is aimed particularly at the developing world, where up to 30 million people require prosthetics, according to the World Health Organization. The issue is not so much about cost—cheap prosthetics exist, and many used ones are donated—but the need for specialists to adjust or replace the sockets. WHO says 180,000 trained staff are needed, and that there’s a current shortage of about 40,000. Outfitting an average prosthetist’s clinic, complete with grinders and vacuum formers, costs $70,000, according to Hill, and that’s before you hire personnel to run it.
"Initially, we were thinking about making a cheaper socket, maybe using 3-D printing, or some other advanced manufacturing technique," Hill says. "But then we found out the real problem was the shortage of trained care. The 40,000 figure really jumped out at us."
BETH, or Benevolent Technologies For Health, grew out of a Hacking Medicine event at MIT, where it won a prize. The project was also picked as a runner-up prize in this year’s Dyson Awards. Hill, and partners Elizabeth Tsai, and Asa Hammond, are now looking for investors, and running through new prototypes.
Aside from the technology, one of the main challenges may be to persuade specialists who understandably take pride in their ability to shape sockets for their patients. "It’s quite disruptive," Hill says. "So far, of the prosthetists we’ve talked to, the ones at the VA have been more supportive. They really look at it as in 'what is the best way we can provide affordable care?' Some of the private prosthetists don’t want to relinquish what they do."