Article

Spinal cord injury (SCI) can compromise the ability to maintain an erect seated
posture. This study examined the feasibility of a sensor-based threshold
controller to automatically modulate stimulation to paralyzed hip and trunk
extensor muscles to restore upright sitting from forward leaning postures.
Forward trunk tilt was estimated from the anterior-posterior component of
gravitational acceleration sensed by a sternum-mounted wireless accelerometer.
Stimulation increased if trunk tilt exceeded a specified flexion threshold and
ceased once upright sitting was resumed. The controller was verified
experimentally in five volunteers with SCI and successfully returned all subjects
to upright postures from forward leaning positions. Upper-limb effort exerted
while returning to erect posture was significantly reduced (to 7.4% +/- 3.7% of
body mass) pooled across all volunteers while using the controller compared with
using continuous and no stimulation (p < 0.03). Controller response times were
consistent among subjects when applied while sitting with (0.30 +/- 0.05 s) or
without a backrest (0.34 +/- 0.11 s). The controller enabled volunteers to lean
farther forward (59.7 degrees +/- 16.4 degrees ) in wheelchairs without
upper-limb effort than with no stimulation. Clinical utility of the system for
facilitating reach or preventing falls remains to be determined in future
studies.

Langue : ANGLAIS