MIT researchers revolutionized prosthesis technology by allowing amputees to walk again via nervous system control.
The research features a surgical method and robotic technology that restore a normal walking gait regulated by the user's nervous system. Instead of robotic sensors and algorithms controlling movement at fixed rates, this novel technique offers intuitive control, similar to natural limb movement, per US News & World Report.
While walking, reconnecting residual limb muscles improves real-time prosthetic limb position feedback. Researchers found that seven patients who had this operation had better walking speed, obstacle avoidance, and stair climbing than those with traditional amputations.
Improved, More Natural Movement
Senior researcher Hugh Herr, co-director of MIT's K. Lisa Yang Center for Bionics, stressed brain control's importance in natural gait. Herr noted that there were no records in the past that demonstrated a degree of brain control simulating natural movement, "where the human nervous system directs the motion, not a robotic algorithm."
Traditional below-the-knee amputation disrupts the coordinated muscle movements needed for precise limb control, making ordinary prostheses difficult to adjust to diverse terrains and obstacles. The new agonist-antagonist myoneural interface (AMI) surgery, on the other hand, keeps the dynamic muscle connection in the residual limb, which makes neural feedback and control better.
AMI surgery patients walked more naturally than non-amputation patients, according to the study. They synchronized their prosthetic and natural limbs to push off the ground with identical power.
Lead researcher Hyungeun Song stressed the importance of brain feedback in restoring functional mobility, adding that even a little increase in sensory input enhances prosthesis controllability. This advancement allows future prostheses to be more smoothly integrated with the body, improving user embodiment and quality of life.
Check out this video showcasing the breakthrough prosthetic:
Improved Sensory Feedback Recorded
In the pioneering study, researchers compared seven AMI patients to seven with standard below-the-knee amputations. Each participant used an advanced prosthetic limb with a motorized ankle and electrodes to monitor leg muscle electromyography (EMG) signals, according to MIT's blog.
The research evaluated respondents' ability to walk on flat ground, slopes, ramps, stairs, and obstacles.
Patients receiving the AMI neuroprosthetic interface have dramatically improved movement. They walked quicker, virtually matching non-amputation patients, and used more natural actions like altering the prosthesis's toe angle while ascending stairs or stepping over barriers. They also coordinated their prosthetic and undamaged limbs better, exerting equivalent ground force as non-amputees.
Senior researcher Herr noted that the AMI patients showed biomimetic tendencies, while the typical amputation group moved more slowly.
Patients with AMI had better brain control but received 20% less sensory feedback than undamaged limbs. Lead researcher Hyungeun Song said this improved input helped users modify their pace, adapt to different terrains, and avoid hazards.
The study's co-author, Brigham, and Women's Hospital surgeon Matthew Carty, stressed the transformational power of joint research in managing severe limb injuries.
The MIT K. Lisa Yang Center for Bionics and the Eunice Kennedy Shriver National Institute of Child Health and Human Development funded the research, which advances Herr's goal of integrating prosthetic limbs more seamlessly with the human body to improve user experience and embodiment beyond robotic controls and sensors.
According to The Washington Post, the researchers expect to commercialize the breakthrough prosthesis within five years. Herr said that they are starting to see a "glorious future" wherein technology can reconstruct an important part of the body that has been lost.
