The Natural Artificial Foot

SMOOTHER THAN IT LOOKS :

Tensioned cables act like tendons in Rifkin’s magnesium foot.
Photo by John B. Carnett

Popsci.com

"Gordon Link, a diabetic and foot amputee, is not looking to climb Mount Everest, run a marathon, or snowboard off a cliff. “I just want to walk without stumbling like I’m a drunk,” he says. It may not sound like a tall order, but until he was fitted with a prototype prosthetic foot that simulates the body’s natural movements, walking on uneven ground was like navigating an obstacle course. “Hitting a low spot of even one inch with my old foot was like a non-amputee stepping into a four-inch hole,” he adds. “Not good.”
Link has been testing the new foot for the past six months, but 36-year-old inventor Jerome Rifkin has been building and rebuilding the flexible mechanical foot for more than eight years—ever since he broke his hip in a bicycle accident and spent three years learning to walk again. The mechanical engineer had studied prosthetics as an undergrad, but his physical therapy was a crash course in the biomechanics of walking. “That’s when I realized that prosthetic feet were nothing like natural feet,” he says.

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."

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