In a notable advancement for prosthetic technology, a team from MIT and Brigham and Women’s Hospital has introduced a revolutionary approach that enables a prosthetic limb to be driven directly by the body’s nervous system. The new technique, known as the agonist-antagonist myoneural interface, reestablishes connections between muscle pairs in the residual limb, allowing users to receive vital proprioceptive feedback. This feedback helps them perceive the limb’s position and movement more naturally, significantly improving the gait and overall functionality of the prosthetic.
Traditional prosthetic limbs rely on robotic controls and sensors to mimic natural movement, but these systems often lack the intuitive feel of a real limb. The AMI surgery, pioneered by MIT’s Hugh Herr and his team, transforms this paradigm by reconnecting muscle pairs within the residual limb. This connection restores the natural interaction between agonist and antagonist muscles, enhancing the user’s ability to control their prosthetic limb with greater precision and ease.
A recent study published in Nature Medicine highlighted the efficacy of this new approach. In the study, seven patients who underwent the AMI procedure demonstrated remarkable improvements in their ability to walk naturally. They could navigate various terrains, including stairs and slopes, with greater ease compared to those with traditional prosthetics. The AMI recipients walked faster and with a more natural gait, mirroring the movements of individuals without amputations.
The prosthetic limbs used in this research were equipped with advanced technology, including powered ankles and electrodes to detect electromyographic signals from the residual muscles. These signals were processed by a robotic controller to adjust the prosthetic’s movement dynamically. The AMI procedure enhanced this system by integrating neural signals more closely with the prosthetic control, leading to smoother and more natural movements.
The study also revealed additional benefits of the AMI procedure. Patients experienced less pain and muscle atrophy compared to those with traditional amputations. This improvement is attributed to the restoration of natural muscle interactions, which helps maintain muscle function and reduces discomfort. Despite providing less than 20% of the sensory feedback typically experienced by non-amputees, the AMI procedure still significantly enhanced prosthetic control and gait.
Hugh Herr, who leads the research at MIT’s K. Lisa Yang Center for Bionics, describes this approach as a transformative step in prosthetic technology. By reconnecting the nervous system directly with the prosthetic limb, the AMI procedure offers a more integrated and holistic solution. This advancement aligns with the broader goal of "rebuilding human bodies," where technology becomes an intrinsic part of the user’s anatomy rather than an external aid.
Funded by MIT’s K. Lisa Yang Center for Bionics and the Eunice Kennedy Shriver National Institute of Child Health and Human Development, this research represents a significant leap forward in the field of bionics. The collaboration between MIT and Brigham and Women’s Hospital showcases the power of interdisciplinary research in advancing medical technology and improving the quality of life for individuals with amputations. As this technology continues to evolve, it holds the potential to further integrate prosthetics with human physiology, enhancing mobility and comfort for many.
