Article

In order to achieve efficacious walking, transfemoral amputees must adapt
coordination within both the artificial and the sound lower limb. We analyzed
kinematic strategies in amputees using the planar covariation of lower limb
segments approach. When the elevation angles of the thigh, shank and foot are
plotted one versus the others, they describe a regular loop which lies close to a
plane in normal adults' gait. Orientation of this plane changes with increased
speed, in relation to mechanical energetic saving. We used an opto-electronic
device to record the elevation angles of both limbs' segments of novice and
expert transfemoral amputees and compared them to those of control subjects. The
statistical structure underlying the distribution of these angles was described
by principal component analysis and Fourier transform. The typical elliptic loop
was preserved in prosthetic walking, in both limbs in both novice and expert
transfemoral amputees. This reflects a specific control over the thigh elevation
angle taking into account knowledge of the other elevation angles throughout the
gait cycle. The best-fitting plane of faster trials rotates around the long axis
of the gait loop with respect to the plane of slower trials for control subjects,
and even more for the sound limb of expert amputees. In contrast, plane rotation
is very weak or absent for the prosthetic limb. We suggest that these results
reveal a centrally commanded compensation strategy.
CI - Copyright (c) 2011 Elsevier B.V. All rights reserved.

Langue : ANGLAIS