Current bionic legs use predefined robotic control architectures, limiting their versatility. This study hypothesized that continuous neural control of a bionic limb, augmented by residual muscle afferents, could restore biomimetic gait after below-knee amputation. A neuroprosthetic interface was developed with surgically connected agonist-antagonist muscles and muscle-sensing electrodes. In seven leg amputees, the interface augmented residual muscle afferents, leading to a 41% increase in maximum neuroprosthetic walking speed compared to a control group. Biomimetic adaptation to varying speeds and diverse environments (slopes, stairs, obstacles) was also observed. The results suggest that even small augmentation of residual muscle afferents, combined with continuous neuromodulation, restores biomimetic gait.

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