“World First” Thought-Controlled Bionic Leg

The Rehabilitation Institute of Chicago (RIC) has revealed clinical application of the world’s first thought-controlled bionic leg in the New England Journal of Medicine(NEJM). This innovative technology, funded in part by the US Army, represents a significant milestone in the rapidly-growing field of bionics.


Until now, only bionic arms could be thought-controlled. That may be changing, as researchers at RIC’s Center for Bionic Medicine, have developed a system to use neural signals to safely improve limb control of a bionic leg. This method improves upon prosthetic legs that only use robotic sensors and remote controls and do not allow for intuitive thought control of the prosthetic.

The case, published in the NEJM focuses on RIC research subject Zac Vawter, a lower-limb amputee who underwent a procedure known as targeted muscle reinnervation surgery in 2009 to redirect nerves from damaged muscle in his amputated limb to healthy hamstring muscle above his knee. When the redirected nerves instruct the muscles to contract, sensors on the patient’s leg detect tiny electrical signals from the muscles. A specially-designed computer program analyzes these signals, together with data from sensors in the robotic leg. It instantaneously decodes the type of movement the patient is trying to perform and then sends those commands to the robotic leg. Using muscle signals, instead of robotic sensors, makes the system safer and more intuitive. It may not be true “thought control”, but the essence of the system is that the amputee can use this computerised feedback loop to effectively learn how to control his or her lower limb.

The development was facilitated with $8M funding from the US Army’s Telemedicine and Advanced Technology Research Center (TATRC).

Researcher comments

“This new bionic leg features incredibly intelligent engineering,” said lead scientist Levi Hargrove, PhD. “It learns and performs activities unprecedented for any leg amputee, including seamless transitions between sitting, walking, ascending and descending stairs and ramps and repositioning the leg while seated.”

Amputee comments

“The bionic leg is a big improvement compared to my regular prosthetic leg,” stated lower limb amputee Zac Vawter. “The bionic leg responds quickly and more appropriately, allowing me to interact with my environment in a way that is similar to how I moved before my amputation. For the first time since my injury, the bionic leg allows me to seamlessly walk up and down stairs and even reposition the prosthetic by thinking about the movement I want to perform. This is a huge milestone for me and for all leg amputees.”

Source: Rehabilitation Institute of Chicago, PR Newswire