Article

We performed this study to determine the feasibility
of controlling and stabilizing seated posture with functional
electrical stimulation (FES) after paralysis from spinal cord
injury (SCI) using computer simulations and a 3-dimensional
model of the hip and trunk. We used the model to approximate
the range of postures in the sagittal and transverse planes
attainable by a seated subject and to estimate the maximum
restorative moment that could be produced in a neutral posture
in response to a disturbance. The simulations predicted that
approximately 28 degrees of forward flexion in the sagittal
plane (combined hip and trunk) and 9 degrees of lateral bending
in the transverse plane should be possible with FES and
that a maximum disturbance rejection moment of approximately
45 newton meters could be expected with the chosen
muscle set. We tested a subject with a motor complete thoracic
SCI and implanted electrodes in a subset of the selected muscles
to compare the moments the subject required to maintain
various hip and trunk positions with those predicted by the
model. Although a significant range of seated postures was
possible with FES, the data demonstrated that more complete
activation of the paralyzed muscles would be needed for the
subject to fully achieve the theoretical range of motion. With
further refinements, we could apply these techniques to the
design of control systems for regulation of seated posture and
dynamic motion of the torso.

Langue : ANGLAIS