Article

OBJECTIVES: (1) To test the validity of a trifilar pendulum in estimating moments
of inertia (MOIs) for running-specific prostheses (RSPs), (2) to measure inertial
properties (mass, center of mass [CM] position, and MOIs) for 4 RSPs, (3) to
verify the influence of the stiffness on the inertial properties of RSPs, and (4)
to develop a predictive equation to estimate RSP CM positions. DESIGN: An
aluminum block with known MOIs was used for verifying the accuracy of the
trifilar pendulum MOI measurements. MOI errors were investigated by
systematically misaligning the block and pendulum principal axes across a range
of 1 to 10cm. Mass, CM position, and MOI were tested across 4 RSP designs with 3
stiffness categories each. SETTING: University biomechanics laboratory.
SPECIMENS: Four different RSP designs and 3 stiffness categories per design were
examined. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: MOI errors from
known values and principal axis misalignments between RSPs and pendulum; mass, CM
positions, and RSP principal axis MOIs; and predictive equation CM position
errors. RESULTS: The trifilar pendulum estimated MOIs within -6.21x10(-5)kg/m(2)
(</=1% error) for a block with known MOIs. Misalignments of 1 to 5cm between the
RSPs' and pendulum's CM yielded errors from .00002 to .00113 kg/m(2)
(0.3%-59.2%). Each RSP's inertial properties are presented. MOIs about any axis
varied <.004kg/m(2) across stiffness categories; MOIs differed up to .013kg/m(2)
between different designs. The predictive CM equation erred between .010 and
.028m when using average input values across an RSP design. CONCLUSIONS: Trifilar
pendulums can accurately measure RSP MOI. The RSP inertial properties differed
slightly across stiffness categories within each design, but differed more
substantially across different RSP designs. Using a predictive equation to
estimate RSP CM positions can provide adequate data, but directly measuring CM
positions is preferable.
CI - Copyright (c) 2013 American Congress of Rehabilitation Medicine. Published by
Elsevier Inc. All rights reserved.

Langue : ANGLAIS