The current state of bionic limbs from the surgeon’s viewpoint

Amputations have a devastating impact on patients’ health with consequent psychological distress, economic loss, difficult reintegration into society, and often low embodiment of standard prosthetic replacement. The main characteristic of bionic limbs is that they establish an interface between the biological residuum and an electronic device, providing not only motor control of prosthesis but also sensitive feedback. Bionic limbs can be classified into three main groups, according to the type of the tissue interfaced: nerve-transferred muscle interfacing (targeted muscular reinnervation), direct muscle interfacing and direct nerve interfacing. Targeted muscular reinnervation (TMR) involves the transfer of the remaining nerves of the amputated stump to the available muscles. With direct muscle interfacing, direct intramuscular implants record muscular contractions which are then wirelessly captured through a coil integrated in the socket to actuate prosthesis movement. The third group is the direct interfacing of the residual nerves using implantable electrodes that enable reception of electric signals from the prosthetic sensors. This can improve sensation in the phantom limb. The surgical procedure for electrode implantation consists of targeting the proximal nerve area, competently introducing, placing, and fixing the electrodes and cables, while retaining movement of the arm/leg and nerve, and avoiding excessive neural damage. Advantages of bionic limbs are: the improvement of sensation, improved reintegration/embodiment of the artificial limb, and better controllability. Cite this article: EFORT Open Rev 2020;5:65-72. DOI: 10.1302/2058-5241.5.180038

Multimaterial and multifunctional neural interfaces: from surface-type and implantable electrodes to fiber-based devices

Development of neural interfaces from surface electrodes to fibers with various type, functionality, and materials.

Predicting neural recording performance of implantable electrodes

Electrode impedance at low frequencies was a stronger predictor of electrophysiological performance than the typically reported impedance at 1 kHz.