With a greater spring in your step
If something were to happen to you tomorrow - a debilitating accident or the sudden onset of a degenerative disease you never knew you had - what would you do? How would you feel? These thoughts came to my mind as I went about researching the topic of prosthetics. These mechanical devices had little to do with me right now, but I what if I needed them to help me lead a normal life somewhere down the road? As an athlete who grew up with sports as an integral part of my life, I wonder how I’d take the news that I would never walk or see, never mind running or cycling. There is a breed of heroes amongst us, people who transform lives that have been seemingly destroyed, and MIT Media Lab Professor Hugh Herr and his team are part of this breed.
They developed the ankle-foot, aptly named after the body part it seeks to replace. Perhaps emulate is a better word, since it strives to give amputees the spring in their step back. The ankle-foot propels users forward using tendon-like springs and an electric motor. It reduces fatigue, improves balance and provides amputees with a more fluid gait than they would have with their conventional passive-elastic prosthesis. The prosthesis is capable of propelling the wearer forward and varying its stiffness over terrains, successfully mimicking the action of a biological ankle.
An below-knee amputee walking with the powered ankle-foot prosthesis
Looking at the video above, it is evident how normally the patient walks and has regained most, if not all normal walking function of the foot. There is no doubt that an invention such as this will dramatically improve the lives of many amputees still moving around in wheelchairs or using conventional prostheses that offer little flexibility or even adaptation to the terrain like the natural foot does.
“With 26 bones, 35 joints, and the awesome responsibilities of weight-bearing and propulsion, the foot is one of the trickiest body parts to mimic. Today, amputees must choose between mechanical models, which rely on flat carbon-fiber platforms that bend slightly with each step, or a computer-controlled motorized foot that better reproduces a natural gait but can cost up to $18,000 and often isn’t covered by insurance.” [1] This is where Gordon Link, a diabetic and foot amputee, hopes to bridge that gap with the K3 Promoter which mimics the jointed motion of a real foot for easier walking.
While these technologies are developed and tested, the collaboration across fields will help expedite the process of bringing them to market and give the ability to walk back amputees. The way forward will be osseointegration - directly joining these devices to human bone at the extremities of the amputation, leading to efficient energy transfer, increased comfort as well as control.
It’s only a matter of time that these inventions begin to touch the lives of millions out there waiting to regain their place in the world.
- Yan Liang
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[1] PopSci: The Natural Artificial Foot
Another revolutionary foot prosthetic: Proprio Foot
