Stimulus adjustment protocol for FES-induced standing in paraplegia using percutaneous intramuscular electrodes

The desirable upright posture for standing via functional electrical stimulation (FES) is defined based on simulation results using a link model in the sagittal plane. The criterion for the posture selection is the minimization of the sum of the squared joint flexion moments caused by gravity. The stimulus intensities are adjusted systematically to attain the defined upright posture. Controlled standing was achieved in a Th7 and a Th8-level spinal-cord-injured paraplegic individuals without joint contracture, by using the stimulus adjustment protocol. A practical standing without any bracing devices was obtained, with the vertical upper extremity support of less than four percent of the body weight, and with single-hand-support attainable. The maximal durations of standing were 30 minutes in both cases.