The lack of sensory information in conventional prostheses has previously been shown to reduce walking confidence and speed in people with transfemoral amputations, which are associated with high mental and physical fatigue. Past research has also indicated that the lack of physiological feedback to the brain also contributes to the generation of phantom limb pain. To determine whether neural sensory feedback restoration could address these issues, researchers implanted four intraneural stimulation electrodes in the remaining tibial nerve of two people with transfemoral amputations and reported that the sensor-electrode interface resulted in increased walking speeds, lower oxygen consumption, increased concentration, and an 80 percent decrease in reported pain.
The participants were evaluated while using a neuroprosthetic device consisting of a prosthetic leg equipped with foot and knee sensors. The sensors drive neural stimulation, which elicits sensations of knee motion and the sole of the foot touching the ground. A series of tests repeated over three months were conducted with the feedback system turned off, and then repeated with it on.
According to the researchers, the results from the proof-of-concept case study provide the rationale for larger population studies investigating the clinical utility of neuroprostheses that restore sensory feedback.