If Mother Teresa Hacked

She might’ve started a company like D-Rev, which is bringing low-cost prosthetic knees to the world. The company’s Vin Narayan reveals how the non-profit is re-imagining do-gooderism.

If Mother Teresa Hacked
D-Rev’s Vin Narayan.

There are non-profits that want to heal the world, and there are non-profits that want to hack it. D-Rev is one of the latter. At the non-profit design company–one of Fast Company’s Most Innovative this year–a hacker mentality that prizes reason above sentimentality often reigns.


Take one of D-Rev’s biggest initiatives of late–to bring quality prosthetics to the world’s poor. It’s a goal worthy of Mother Teresa, but D-Rev’s tactics are anything but missionary. Far from insisting that its novel prosthetic, the ReMotion Knee, be donated charitably to clinics working with amputees, D-Rev has concluded that charging money for the product will actually help it reach more people in need. “D-Rev is entirely philanthropically driven,” explains Vin Narayan, the ReMotion Knee’s project manager. “The caveat is that the way we think we can accomplish that in a scalable way is often through the methods of the for-profit sector.”

Another company might have sold luxury prosthetics to the rich (“designer body parts” are not unheard of), while giving away cheap stuff to the poor as part of a corporate social responsibility initiative. But with the donation model, says Narayan, “as soon as donations dry up, the solution is gone.”

Furthermore, D-Rev believes that exposing itself to the pressures of the market both helps cover costs and helps D-Rev develop an optimal product. “People have lower expectations for a donated product,” says Narayan. “It’s hard to find out if you’re solving the problem, if people are actually using it.” But if you’re selling a product–even at a low price–then you know you’ve made something people actually value.

Selling, rather than donating, to the poor–it’s a move made with the mind rather than the heart, and perhaps it’s no surprise that the ReMotion Knee’s creators come from that most stereotypically rational of groups: engineers. The prosthetic knee began as a project among Stanford engineering graduate students in 2008; they were later given office space by D-Rev and finally officially merged with the company in 2011.

The engineers wanted to solve a problem: to make a low-cost prosthetic knee. Low-cost options for prosthetic legs and feet were already largely available. But the knee, as a joint, is more intricate than the leg or foot, and an affordable solution for the poor didn’t yet exist. It came down to materials: prosthetic knees for the developed world markets relied on costly titanium.

The team behind the ReMotion Knee reconceived the prosthetic knee, making it out of plastic rather than metal. Traditional prosthetic knees took advantage of titanium’s strength, channeling great forces onto small parts. A plastic knee wouldn’t have that luxury, so the team had to fundamentally rethink how forces would be distributed across the prosthetic.


The ReMotion Knee has been through three versions, each of whose design has been altered depending on its target market. The first version used a connection mechanism specific to a particular partner clinic in India; the second version used a more standardized connection method; a third version has been further tweaked to suit mass production methods. The team is rolling out the latest version of the device to partner clinics throughout the year, and hopes to enter mass production by 2014.

From every angle, at every stage, the ReMotion Knee project bespeaks an engineer’s mind-set, that almost Vulcan-like rationality. But asked whether the key to D-Rev’s success is to eschew the more typical charity’s sentimentality, Narayan actually says the team’s greatest learning moments required a departure from the hacker’s mind-set.

“I’d say we had to bring sentimentality a bit more into the fold” among the ReMotion Knee team, he confesses. The earliest version of the knee, while a feat of engineering, had features that prevented many amputees from becoming fond of the product. “We expected feedback to be around the stability of the knee, but in fact, almost all the feedback centered on things that made the knee less conspicuous–about making it less obvious that the person was an amputee.” Users of the knee’s first version had little to say about how the knee felt, and cared more about the fact that angular components of the device called attention to themselves through clothing, and that the knee sometimes made clicking noises the amputees found embarrassing.

The team made version two more rounded, adding noise bumpers to cut down on sound. “Things like that are sometimes lost on technically minded people,” says Narayan, “but are just as important to getting a product out there. You can develop the best product, but if people don’t like it and don’t use it, all that engineering work was for naught.”

About the author

David Zax is a contributing writer for Fast Company. His writing has appeared in many publications, including Smithsonian, Slate, Wired, and The Wall Street Journal.