An Objective Method for Selecting Command Sources for Myoelectrically Triggered Lower-Limb ProsthesesBy Dutta, Anirban; Kobetic, Rudi; Triolo, Ronald J.; Journal of Rehabilitation Research and Development, Volume 48, Number 8, pages 935-948
Publication Date: 2011
Study identified a process for selecting command sources for triggering functional electrical stimulation (FES) with the surface electromyogram (EMG) from muscles partially paralyzed by incomplete spinal cord injury (iSCI). FES facilitates ambulatory function after paralysis of persons with SCI by exciting the peripheral motor nerves to activate the muscles of the lower limbs. A metric taken from signal detection theory called the Discriminability Index (DI) was used to rank the partially paralyzed muscles according to their ability to detect the intent to step during level overground walking. Two participants with iSCI volunteered for the study. Participant 1 was a 23-year-old male with C7 motor and C6 sensory iSCI resulting in bilateral paralysis, who could stand but could not initiate a step without help from FES. Participant 2 was a 34-year-old male with T1 motor and C6 sensory iSCI resulting in left side paralysis and right side weakness, who could only walk short distances without the help from FES. Participants walked with an implanted switch triggered FES system while the activity of the partially paralyzed musculature was monitored by way of surface recording electrodes. The left erector spinae (ES), with a mean DI of 0.87, for triggering the left step and the right ES, with a mean DI of 0.83, for triggering the right step were the best command sources for Participant 1. The left ES, mean DI of 0.93, for triggering the left step and the right medial gastrocnemius, mean DI of 0.88, for triggering the right step were the best command sources for Participant 2. The results showed that command sources can be selected objectively from surface EMG before a fully implantable EMG triggered FES system for walking is implemented.
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