Figure 8.

Future clinical trial overview for neuroprostheses in proprioceptive sensory restoration

(A) Virtual subject wearing knee prosthesis with sensorized socket (EMG and IMU sensors) for real-time acquisition of physiological and kinematic data.

(B) The data obtained from IMU and EMG sensors embedded in the prosthetic device allow the computation of a real-time NMS model, which predicts the MTU kinematics of muscles of interest (medial and lateral gastrocnemius). The acquired information is subsequently used as an input for the estimation of the natural Ia fibers recruitment and firing rate activity. This activity serves as a modulating variable for the subject-specific calibrated encoding strategy, which produces the real-time electrical stimulus parametrization.

(C) The subject is implanted with multiple electrodes in the tibial branch of the sciatic nerve; IPG neural stimulator applies the appropriate stimulation to the relevant active site.

(D) Biomimetic encoded electrical stimulation generates coherent Ia fibers activation with respect to natural fiber activity. Electrically driven Ia fibers activity is interpreted from the central nervous as proprioceptive feedback, allowing the subject to perceive the flexion/extension of the joint.