A Revolution in Prosthetic Limbs

The Revofit adjustable socket

Sometimes inspiration comes when you least expect it. Joe Mahon knows this all too well. He was sharing a chair lift with his wife when he realized the simple answer to a common problem. The revelation changed the way he’s spent his free time ever since. The problem that Joe is hoping to fix isn’t one that faces everyone; just those of us who happen to be part robot and have carbon fiber or electronics replacing one of our limbs.

Me and my prosthetist, Joe Mahon

Joe is my prosthetist. He’s the guy who makes arms and legs every day at his company, called Peak Prosthetic Designs. He’s the reason I live a pretty normal life with my prosthetic leg. While others in the field spend their time coming up with fancy new feet or robot arms, Joe spends his time looking for simple fixes that will make the socket that slides onto my residual limb more comfortable. Like he always says, “If your leg isn’t comfortable, then who gives a crap how expensive or amazing your foot is?”

Joe has a lot of experience making limbs for amputees in Haiti. He began the trips in 2001, and after the earthquake in 2010 he went every month for 10 straight months. He was often frustrated when he watched a new patient walk out the door with a new limb, knowing if it ever needed adjustments (which most prosthetic limbs do), there was nowhere to turn.

Residual limbs often change in volume. Heat, humidity, weight loss, weight gain…. There are many reasons a socket on a prosthetic leg might not fit correctly. When I take long car rides it’s not uncommon for me to take my leg off and throw it in the back seat. It gets too tight when I sit for too long.

When I walk a lot, ride my bike, or am generally very active, my residual limb shrinks. If I’m extra good about watching what I eat and drop a few pounds, my leg shrinks. I’ve even noticed that when I’m sick for more than a day or two, my leg will temporarily shrink.

To those of us in developed countries, the answers are easier. If I have a volume change in my leg (like losing weight and keeping it off…. I’ve heard rumors that can happen) I can just schedule a five-minute visit to my prosthetist. With a few socket adjustments, I’m once again comfortable. For a Haitian farmer, it’s not so easy. Once his limb changes shape or volume, he’s out of luck. If he needs adjustments, there is no local prosthetist to tweak his fit. He’s left living with a leg that isn’t comfortable and eventually unusable. Joe couldn’t stop thinking about the Haitian amputees he’d left behind and wondering how he could help them have a better quality of life.

A few years later Joe found himself on the ski chair lift, taking a call from a patient as he took in the mountain views. His patient desperately needed one of those five-minute adjustments before she left town later that day. But for that to happen Joe would have to cut short his ski date on a blue bird powder day and drive all the way back down the mountain, just for a five-minute tweak. Once again, this time for more selfish reasons, he wished his amputee patients could adjust their own leg sockets.

Adjustable snowboard boots with Boa Technology. Photo: Boa Technology

After he slid off the chair lift and headed into what would be his last run, he stopped to wait for his wife to adjust her snowboard boots. Trying to be patient, he watched her turn the wheel to unclick, then re-click, the Boa ratcheting system on her boots until she had complete comfort. In that moment Joe had his revelation.

Why couldn’t prosthetic legs be adjusted with a Boa ratcheting system?  What if an amputee could adjust her own leg, with a few clicks of a wheel, finding her own sweet spot of comfort? The lacing worked so well in snowboard boots and other sports shoes, thanks to the patented system by BOA Technologies, why not incorporate it into a leg?

Joe’s wife initially refused his request to tear apart her snowboard boots, so he could see how they worked. After he stepped up the offer and promised her a brand new pair in return, she finally relented. That night, in his basement, he picked up a utility knife and started carefully deconstructing the mysterious Boa ratchet and wiring system. He had to figure out how the snow boot lacing worked before he could marry it to a prosthetic leg. That was February of 2009.

Matt Bradley wearing his adjustable socket

In the next few years Joe did it. He filed a patent, came up with a prototype, then found some willing amputee testers. One was a top U.S. Paralympian biker, Matt Bradley, who happened to wear the Boa lacing system on his riding shoe. He was thrilled to have the same adjustment potential on his prosthetic riding leg itself. Suddenly he could adjust his shoes and his leg without getting off his bike.

As he tested his product on other amputees Joe began to see how his new system could solve other simple problems. For many of us, in the winter months, we have to take off long pants to be able to have access to our limb. It’s one of the sole reasons I wear shorts as long as I can into autumn weather. It’s just easier to fiddle with my leg when I can access it in public. With Joe’s new leg design, there is no need to find the nearest bathroom or department store fitting room. I can reach down, turn the dial a few clicks, then be on my way.

Once he had a product that showed great promise, Joe’s next step was to get Boa Technology on board. For several years he called their headquarters, trying to sell them on the fact that prosthetic limbs could be a new market for their product. Joe had done all the work, by incorporating their product into the creation of a limb, even custom designing a few of the tools needed to make it all come together. All they had to do was agree to let him use their part of the design. Then finally the door opened.

In May of 2012 Joe threw his mountain bike and a box full of arms and legs into his truck and drove to Steamboat Springs to meet with executives from Boa Technology. They liked what they saw.

With constant modifications and improvements, Joe continues to streamline his new idea and come up with ways to make it more user friendly. The beauty of the design is that it incorporates almost all of the already accepted steps in making a limb. With a handful of extra parts that cost less than a hundred dollars, a regular leg can be turned into what Joe calls the Revofit adjustable socket.

New products are constantly being introduced into the field of prosthetics. Only a few of them relate to the specific problem of making an artificial limb comfortable. The idea of an adjustable prosthetic socket could easily be one of those elusive game changers. It’s a new idea, but better than that, it’s a simple idea. As Joe’s Revolimb website points out, “In a world where high tech rules, our low tech approach is simplifying the lives of amputees around the world.”

Soon I hope to be wearing one of Joe’s adjustable legs. Someday, when I pause in the middle of an afternoon to acknowledge that my leg isn’t fitting quite right, instead of searching my calendar for a time I can go in for an adjustment, I’ll just reach down and make a few clicks. Then I’ll get back to my day. All because some guy had a revelation during a day of skiing and refused to let his idea die.

Bonus: Here’s a great video demonstration graphic of the Revofit adjustable limb and a second video of how it works on an actual person.

Get the GeekDad Books!