It鈥檚 virtually impossible to know Mike Sasser鈥檚 left leg is a prosthetic one 鈥� after a decade of practice, he moves surely and swiftly through his busy days as a consultant and father.
But when Sasser encounters uneven ground or a flight of stairs, he focuses very hard on balance, because that鈥檚 when using a prosthetic can mean taking a tumble. For years, he鈥檚 been visiting a Vanderbilt University mechanical engineering laboratory, making a difference by testing a new 鈥渟mart鈥� prosthetic ankle that moves with the user.
Prosthetic ankles available now are static, meaning they don’t anticipate movement and adjust the feet to different terrains. Many users swing the prosthetic leg outward ever so slightly during regular walking to make up for feet that don鈥檛 naturally roll through the motion of walking.
鈥淚鈥檝e tried hydraulic ankles that had no sort of microprocessors, and they鈥檝e been clunky, heavy and unforgiving for an active person,鈥� Sasser said. 鈥淭his isn鈥檛 that. It actually lifts the toe for you. There鈥檚 a definite market for this.鈥�
The device is from the lab of Michael Goldfarb, H. Fort Flowers Professor of Mechanical Engineering; professor of electrical engineering and physical medicine and rehabilitation; and co-director of the Center for Rehabilitation Engineering and Assistive Technology. He鈥檚 perhaps best known for working on a bionic leg with shark attack victim Craig Hutto and later developing the world鈥檚 first easily portable, wearable robot 鈥� the Indego exoskeleton.
The ankle has a tiny motor, actuator, sensors and chip that work together to either conform to the surface the foot is contacting or remain stationary, depending on what the user needs.
Goldfarb said the problem with finding workable prosthetic ankles is so pervasive that many amputees only wear one type of shoe 鈥� whichever one works best with their prosthetic.
鈥淥ur prosthetic ankle is intelligent, so you can wear a dress shoe, a running shoe, a flat 鈥� whatever you鈥檇 like 鈥� and the ankle adapts,鈥� Goldfarb said. 鈥淵ou can walk up slopes, down slopes, up stairs and down stairs, and the device figures out what you鈥檙e doing and functions the way it should.鈥�
Harrison Bartlett, a Ph.D. student in Goldfarb鈥檚 lab, works with Sasser, gathering feedback from the sensors and making adjustments based on both the data and Sasser鈥檚 user experience.
As a participant in the National Science Foundation鈥檚 I-Corps program for budding entrepreneurs, Bartlett also interviewed nearly 100 potential users to understand what would make the ankle a success. His team hopes to commercialize the ankle within the next couple of years.
鈥淚 talked to one person whose favorite restaurant was at the top of a long flight of stairs, so they haven鈥檛 eaten there in 10 years,鈥� he said. 鈥淎nother sat on benches throughout an amusement park while their family enjoyed the rides because they couldn鈥檛 be sure about navigating that with their prosthetic. We want to return people to any of the life activities they want to do.鈥�
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