Article

The use of rocker models to understand functional tasks of the human lower limb
is attractive because of their simplicity. Recent studies have determined a
consistent feature of able-bodied walking termed the roll-over shape (ROS), which
is the effective rocker shape that the lower limb system conforms to between
initial contact and contralateral initial contact during walking. However, it is
unclear what effective rocker shapes are used for fore-aft swaying. A better
understanding of these shapes could be used to develop improved prostheses for
this task, perhaps improving balance and balance confidence, and reducing the
occurrence of falling in lower limb prosthesis users. We measured effective
rocker shapes used by 11 able-bodied persons during walking and fore-aft swaying.
We hypothesized that the curvature of the swaying shapes would be smaller (radius
larger) than that of the walking shapes, providing a more stable interface with
the ground during swaying. The radius (measured as the inverse of the curvature
of the shape) was found to be about 1/3 of the leg length for walking, but over
two times the leg length for swaying. A model examining the effective ankle
stiffness necessary to achieve these curvatures suggests that the stiffness of a
biomimetic prosthetic ankle would need to be over three times higher for fore-aft
swaying than for walking. These results suggest that two separate modes would be
needed in an ankle-foot prosthesis to mimic the physiologic system for walking
and swaying.
CI - Published by Elsevier B.V.

Langue : ANGLAIS