Illustration by Justin Vaughan
The mind can do anything. Just ask William Gadsby.
The retired Marine sergeant lost his right leg above the knee to an improvised explosive device while on patrol in Iraq in 2007. He’s been working with researchers at McGuire Veterans Affairs Medical Center on developing a way for an amputee to use just his thoughts to control a prosthesis. And unlike other research projects that involve chip implantation, the McGuire team is working on a less intrusive device that works through electrodes placed on the scalp instead of implanted into the brain.
And after years of brainstorming, tinkering and improvisation, they’ve made some headway.
Gadsby says prosthetics are reactionary, but using the brain-computer interface to control the device is a game-changer. “It makes the knees react as if it was natural again,” he says. “I don’t have to wait for the leg to catch up to what I want to do; it stays in step with my organic knee.”
He was their perfect test subject, researchers say. Gadsby refuses to allow his prosthetic to slow him down, to keep him from his hobbies of hiking with his family and running.
“He’s always looking for an advantage in his prosthetic,” says John Fox, chief of the Orthotic & Prosthetic Lab in McGuire’s Prosthetic Treatment Center, and a member of the research team.
Prosthetics are mechanical wonders, but they’re still limited. The learning curve is steep as you relearn how to walk, and the process takes extensive training and effort. Even so, it’s awkward and difficult to navigate stairs or ramps, according to Dr. Douglas Murphy, a McGuire and VCU Medical School physician who served as a lead on the project.
Something as simple as bending the knee becomes a complex maneuver with a prosthesis. You have to physically manipulate it when you want to lock it in place and keep it rigid, and again when you want to unlock it so you can bend at the knee to sit, or to move it over an obstacle.
Murphy and other McGuire researchers want to make that easier for their patients. What if you could turn the lock on and off by just thinking about it?
There was some research out there, but it was limited. About 80 percent of people with amputations in the United States have lost a lower limb, and yet most of the research deals with upper extremity loss. Also, much of the research involves devices controlled with implants that required a hole to be drilled through the skull and into the brain. Murphy and the team wanted something less invasive.
They found the part of the brain that controls thought patterns in the lower extremities and attached a series of electrodes that capture electrical impulses generated by the brain. Those brain waves are then picked up by a device that Fox describes as looking like a throwback to the helmets that the Soviets used in the early days of space exploration.
When wearing the device, Gadsby says, he looked like a cosmonaut from a Soviet propaganda poster from the 1960s. “It was fun, but I wouldn’t want to walk around town like that,” he says.
When the electrodes are attached, you visualize bending your knee and the electrical impulse generated by that thought prompts a motor in the prosthesis to make the device unlock and bend. They worked with Gadsby on parallel bars, having him lock and unlock the device. It got to the point where Gadsby bent the joint not by will, but subconscious one day. The team was amazed.
“To me, it was the most incredible thing I’ve seen,” says Fox.
Fox notes that the product has great potential to help the elderly, the group most susceptible to needing amputations because of circulatory problems. Another goal is to design a device that’s less intrusive, and to use commercial, readily available technology.
“It’s a big box and wires now,” says Fox.
Murphy presented findings in February in Las Vegas at a session of the Association of Academic Physiatrists. Florida International University’s Ou Bai is a co-leader in the study.
They’re working on a five-year National Science Foundation grant of about $1 million to continue the work. A prosthetic foot is in development similar to what they did with the knee. They hope to eventually “marry them together,” says Fox.
The team hopes its research will make prosthetic use more natural and easier for amputees.
“It’s [about] improving our patients’ lives, getting amputees to a whole new level,” says team member William Lovegreen.
Gadsby has moved to California and works with the VA as a psychotherapist, helping combat veterans and their families. He says that having more control and more natural movement provides an incredible boost. “To be reduced to something where basically you’re walking on a door hinge, it’s pretty frustrating, he says. “This puts you more on par [with] to more of what you could do.”
