THE FUTURE OF BIONIC LEGS : ENHANCING MOBILITY WITH NEUROPROSTHETICS

 

Neuronally controlled bionic legs with agility and responsiveness comparable to natural limbs have frequently been depicted in science fiction. However, the current state of technology is less remarkable. Today's bionic legs rely on predetermined robotic control systems to simulate natural movement, with finite state machines and pattern recognition used to manage various phases of walking and terrain kinds. This method limits the user's continuous brain control, giving them just limited control over gait.

The Promise of Neuroprosthetics

Neuroprosthetic legs, which are totally controlled by the human neural system, represent a tremendous advancement. These advanced systems would require high-bandwidth neuromodulation to handle walking demands such as adaptive foot posture, shock absorption, and propulsion across different terrains. However, issues arise due to the irregularity of residual motor control in people with normal leg amputations, which frequently results in inadvertent muscle activation. This is why contemporary bionic legs only use brain inputs as auxiliary control signals in traditional gait controllers, restricting users to specified gait phases and unidirectional movements.

How Do Neuroprosthetics Work?

To compensate for the absence of natural sensory feedback from severed limbs, researchers propose adopting electrical nerve stimulation technology. The goal is to increase muscle afferent impulses in the residual limb, allowing for more natural and adaptive movement. The agonist-antagonist myoneural interface (AMI) is an innovative approach that surgically joins residual agonist and antagonist muscles to restore natural muscle dynamics in the severed limb. This technology uses the endogenous sensory organs in the muscles and tendons to generate biological afferents, or sensory signals, that correspond to joint movements. Preliminary research has demonstrated that AMI can enhance neural regulation of leg motions, notably during the swing phase of gait.

AMI patients were able to control ankle angles and power output to replicate normal joint movements, resulting in faster walking speeds and higher gait energies. Their walking mechanics restored natural kinematics in the rest of the lower extremity joints, resulting in improved symmetry and overall gait performance.

Advances in neuroprosthetic technology have the potential to significantly improve the quality of life for those who have had limbs amputated. These technologies can help users regain mobility and independence by allowing them to move more naturally and adaptively.

REFERENCE:

Hyungeun Song, Tsung-Han Hsieh, Seong Ho Yeon, Tony Shu, Michael Nawrot, Christian F. Landis, Gabriel N. Friedman, Erica A. Israel, Samantha Gutierrez-Arango, Matthew J. Carty, Lisa E. Freed, Hugh M. Herr. Continuous neural control of a bionic limb restores biomimetic gait after amputation. Nature Medicine, 2024; DOI: 10.1038/s41591-024-02994-9

COVER IMAGE SOURCE:

https://www.hackensackmeridianhealth.org/en/healthu/2020/12/18/what-are-the-different-types-of-prostheses