A new surgical procedure that harnesses neural feedback from a residual limb to enable amputees to achieve a more natural walking gait has shown remarkable results.
MIT researchers developed the innovative approach in collaboration with Brigham and Women’s Hospital in Boston, Massachusetts, as reported in a study involving seven patients.
Traditional prosthetic limbs rely heavily on robotic sensors and controllers, which move the limb using predefined gait algorithms.
However, these systems do not provide complete neural control, limiting the user’s ability to walk naturally.
The new surgical technique – agonist-antagonist myoneural interface (AMI) – reconnects muscles in the residual limb, restoring ‘proprioceptive’ feedback that allows patients to sense the position of their prosthetic limb in space.
In the study, AMI surgery patients demonstrated significantly improved mobility. They could walk faster, navigate obstacles and climb stairs more naturally than those with traditional amputations. They also experienced less pain and muscle atrophy.
Hugh Herr, professor of media arts and sciences and senior author of the study, said: This is the first prosthetic study in history to show a leg prosthesis under full neural modulation, producing a natural gait driven by the human nervous system rather than a robotic control algorithm.’
The AMI procedure maintains natural muscle interactions by connecting the muscles’ ends, allowing them to communicate dynamically within the residual limb.
The approach enables the nervous system to control muscle movements better and generate electrical signals that can be used to command the prosthetic limb, providing real-time feedback about the limb’s position.
In various walking scenarios, including level-ground walking, slopes, ramps and stairs, patients with the AMI neuroprosthetic interface outperformed those with traditional prostheses.
They exhibited more natural movements and better coordination between prosthetic and intact limbs, even pushing off the ground with comparable force to non-amputees.
The AMI neuroprosthetic interface represents a significant advancement in prosthetic technology. Enhancing neural feedback helps users feel more connected to their prosthetic limb, promoting a sense of embodiment often missing with robotic controllers and sensors.
Matthew Carty, a surgeon at Brigham and Women’s Hospital and co-author of the study, said: ‘This work demonstrates the potential to restore function in patients with severe limb injuries through collaborative research and innovation.’
The research marks a significant step towards ‘rebuilding human bodies’ and improving the quality of life for amputees.
The study, led by Hyungeun Song, a postdoc at MIT’s Media Lab, was published in Nature Medicine and funded by the MIT K. Lisa Yang Centre for Bionics and the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
Photo courtesy of Hugh Herr and Hyungeun Song
