Article

The trajectories of skin-mounted markers tracked with optical motion capture are
assumed to be an adequate representation of the underlying bone motions. However,
it is well known that soft tissue artifact (STA) exists between marker and bone.
This study quantifies the STA associated with the hindfoot and midfoot marker
clusters of a multi-segment foot model. To quantify STA of the hindfoot and
midfoot marker clusters with respect to the calcaneus and navicular respectively,
fluoroscopic images were collected on 27 subjects during four quasi-static
positions, (1) quiet standing (non-weight bearing), (2) at heel strike
(weight-bearing), (3) at midstance (weight-bearing) and (4) at toe-off
(weight-bearing). The translation and rotation components of STA were calculated
in the sagittal plane. Translational STA at the calcaneus varied from 5.9+/-7.3mm
at heel-strike to 12.1+/-0.3mm at toe-off. For the navicular the translational
STA ranged from 7.6+/-7.6mm at heel strike to 16.4+/-16.7mm at toe-off.
Rotational STA was relatively smaller for both bones at all foot positions. For
the calcaneus they varied between 0.1+/-2.2 degrees at heel-strike to 0.2+/-0.6
degrees at toe-off. For the navicular, the rotational STA ranged from 0.6+/-0.9
degrees at heel-strike to 0.7+/-0.7 degrees at toe-off. The largest translational
STA found in this study (16mm for the navicular) was smaller than those reported
in the literature for the thigh and the lower leg, but was larger than the STA of
individual spherical markers affixed to the foot. The largest errors occurred at
toe-off position for all subjects for both the hindfoot and midfoot clusters.
Future studies are recommended to quantify true three-dimensional STA of the
entire foot during gait.
CI - Copyright (c) 2011. Published by Elsevier B.V.

Langue : ANGLAIS