Two amputees, part of a trial in Copenhagen, are the first in the world to control their lower-limb prosthesis with their minds—subconsciously. As reported by Amy Pollock, writing for Reuters, the two have tiny implanted myoelectric sensors (IMES) surgically placed in their muscle tissue. An Icelandic orthopedics company called Össur developed the sensors and they trigger movement via a receiver.
Gummi Olafsson, one of the two amputees, lost his right foot and lower leg years after a childhood traffic accident. The implants worked for him almost instantly, he reported.
Pollock quoted Olafsson as saying, “As soon as I put my foot on, it took me about 10 minutes to get control of it. I could stand up and just walk away. Come back, sit down, use my muscles to move my foot in the position I wanted to use it. It was, like you couldn’t believe the feeling when you were moving your ankle. It was really strange. I couldn’t explain it. It was like, I was moving it with my muscles, there was nobody else doing it, the foot was not doing it, I was doing it, so it was really strange and overwhelming.”
The 5 millimeters long and 3 millimeters wide Implanted Myoelectric Sensors were provided by the U.S.-based Alfred Mann Foundation, which develops medical technology for use in patients.
Pollock reports that Olafsson’s body continues to adapt to his prosthetic limb more each day, allowing him increased control of it.
“Your muscles are always getting bigger…. So everyday if you are using it, you’re always getting more and more control over what you’re doing with your foot, so in a way, everyday you’re learning more about how to walk properly with the foot, how to use it to go downhill, uphill, downstairs, upstairs, even sitting down and standing up from a chair, ” Olafsson said.
Orthopedic surgeon and Össur’s director of research and development, Dr. Thorvaldur Ingvarsson, implanted the sensors in the two patients involved in the trial. He said that the sensors allow the patient’s brain to control both subconscious and intentional movements.
He explained, “So, the brain power, when it takes over, it actually gives impulses through the brain into the muscles, then the muscles contract. We put sensors into the muscles, and the muscles would pick up the signals, and the signals move their way into the prosthetics, and then the prosthetics react as your brain wants.” Össur anticipates that the system will be on the market within three to five years.
