Bionic leg helps people with amputation walk using mind control

A groundbreaking advancement in prosthetic technology is transforming the lives of individuals with amputations, allowing them to walk more naturally and navigate obstacles with greater ease.

Developed through a collaboration between MIT researchers and Brigham and Women's Hospital, this innovative surgical procedure and neuroprosthetic interface provide enhanced neural feedback from the residual limb, making the prosthetic limb feel more like a natural extension of the body.

How does it work?

State-of-the-art prosthetic limbs typically rely on robotic sensors and predefined gait algorithms, limiting the user's neural control over the limb. This new approach involves a surgical intervention called the agonist-antagonist myoneural interface (AMI), which reconnects muscles in the residual limb. This reconnection allows patients to receive proprioceptive feedback, helping them sense the position and movement of their prosthetic limb. During the procedure, the natural interactions between pairs of muscles are preserved, enabling dynamic communication within the residual limb.

"With the AMI amputation procedure, we attempt to connect native agonists to native antagonists in a physiological way so that after amputation, a person can move their full phantom limb with physiologic levels of proprioception and range of movement," explains Hugh Herr, a professor at MIT and senior author of the study.

Why does it matter?

The implications of this technology are profound. In a study involving seven patients who underwent AMI surgery, the researchers found that these individuals could walk faster, avoid obstacles more effectively, and climb stairs more naturally compared to those with traditional amputations. Additionally, patients experienced less pain and muscle atrophy, significantly improving their overall quality of life.

"One of the main findings here is that a small increase in neural feedback from your amputated limb can restore significant bionic neural controllability," says Hyungeun Song, the lead author of the paper. This level of control enables users to adjust their gait volitionally, adapting to various terrains and obstacles, enhancing their mobility and independence.

The context

This innovative procedure represents a significant step toward the goal of "rebuilding human bodies," a vision championed by Herr's lab at MIT. Traditional prosthetic limbs, despite their sophistication, often fail to feel like a part of the user's body. By enabling direct neural control, this new approach fosters a sense of embodiment, making the prosthetic limb feel more integrated with the user's body.

"This is the first prosthetic study in history that shows a leg prosthesis under full neural modulation, where a biomimetic gait emerges," says Herr. "No one has been able to show this level of brain control that produces a natural gait, where the human's nervous system is controlling the movement, not a robotic control algorithm."

The research, funded by the MIT K. Lisa Yang Center for Bionics and the Eunice Kennedy Shriver National Institute of Child Health and Human Development, continues to push the boundaries of what is possible in prosthetic technology, promising a future where individuals with amputations can regain a more natural and functional way of moving.