A cutting-edge surgical procedure now offers individuals with amputations enhanced neural feedback from their remaining limb, allowing them to walk more naturally. In a recent study involving seven patients, researchers demonstrated that those who received this innovative surgery could walk faster, more seamlessly navigate obstacles, and climb stairs with a gait resembling that of individuals without amputations.
Traditionally, advanced prosthetic limbs rely on robotic sensors and preset algorithms to mimic walking motions. However, this new approach, developed by MIT researchers in collaboration with colleagues at Brigham and Women’s Hospital, taps directly into the body’s nervous system. The procedure, known as the agonist-antagonist myoneural interface (AMI), reconnects muscle pairs in the residual limb during amputation or revision surgery. This reconnection restores the natural communication between muscles, enabling the user’s nervous system to accurately sense limb position and movement—providing essential proprioceptive feedback.
In the study published in Nature Medicine, patients with the AMI surgery showed a marked improvement in their ability to control their prosthetic limb. The reconnection allowed for direct neural modulation, meaning that instead of relying on robotic algorithms, the prosthesis moved in response to the patient’s own muscle signals. This resulted in a natural, biomimetic gait, with patients managing different terrains—such as level ground, slopes, and stairs—with ease. They even demonstrated the ability to adjust their movements in real time, for instance, by raising the prosthetic toe when climbing stairs or stepping over obstacles.
Hugh Herr, professor at MIT and co-director of the K. Lisa Yang Center for Bionics, highlighted that this is the first study to show full neural control of a leg prosthesis. He noted that the approach enables the user’s brain to dictate limb movement rather than a pre-programmed robotic system. Additionally, patients experienced benefits beyond improved mobility: they suffered less pain and showed reduced muscle atrophy compared to those with conventional amputations.
The AMI technique has already been applied to about 60 patients worldwide and is adaptable for upper-limb amputations as well. By restoring natural muscle interactions, the procedure significantly enhances the wearer’s ability to control the prosthetic limb, offering a level of movement and sensory feedback that was previously unattainable.
This breakthrough not only represents a significant advancement in prosthetic technology but also moves toward the broader goal of fully integrating prosthetic devices with the human body. As Herr explains, achieving a direct neural connection is essential for making the prosthesis feel like an authentic part of the body rather than an external tool.
The research received funding from the MIT K. Lisa Yang Center for Bionics and the Eunice Kennedy Shriver National Institute of Child Health and Human Development, marking a transformative step in patient care for those with limb loss.
