Can Science Recreate The Human Foot?

Prosthetic limbs aren’t really anything new. The ancient Egyptians first developed fiber-based artificial limbs thousands of years ago. Later prosthetic devices were made of wood and metal, leather and paper, and, more recently, plastic, aluminum and silicone. But recent innovations in the field of prosthetics have brought us closer than ever to making artificial legs and feet that feel like walking on the real thing. And we have one man in particular to thank for that.

Hugh Herr was only 17 when he lost both feet to frostbite. He and a friend had gotten lost in a January snowstorm while climbing, and spent three days huddled together in the freezing cold. Tragically, a member of the search party was killed by an avalanche, and Jeff Batzer, Herr’s climbing companion, lost part of his left leg, his other toes, and some of his fingers. Hugh Herr also had significant frostbite damage, and had to have both legs amputated a little below the knee. While the loss of his lower legs was difficult, Herr managed not only to salvage his life, but to make it something wonderful, a life that would benefit amputees the world over.

Now working as an associate professor at MIT, Herr specializes in biomechatronics and has revolutionized the field of prosthetic devices. Herr has realized that artificial limbs don’t have to just attempt to be as good as a human foot—they can actually improve on it. He’s developed prosthetics for himself that enable him to be a better climber, giving himself greater height (to reach higher handholds) and the ability to stand on narrow ledges too slim for a human foot.

Perhaps most importantly, his forays into making intelligent and responsive prosthetic devices have produced artificial limbs that allow for walking on different terrains, including uphill (difficult at best with previous prosthetic models), and that recreate a normal human gait. Using springs, microprocessors, and a 25-volt battery, this artificial foot (the PowerFoot) reproduces (and even improves on) the human body’s use of tendons, ligaments and nerves to move the body forward, and does it even more efficiently than a fully biological human foot. A special liquid in the device thickens when exposed to a magnetic field, enabling the artificial foot to brake as needed (much as a human ankle does) when walking downhill.

While the human body has been the standard for natural beauty for millennia, Hugh Herr takes the view that artificial limbs can be as aesthetically appealing as natural limbs, or even more so. Not one to hide his work, Herr often poses for photographs with pant-legs rolled up to expose the metal-and-microprocessor devices he’s developed. And, with his slight smile and relaxed posture, he makes us all realize what a wonder these artificial limbs can be.