Article

Estimating the inertial parameters for the foot (mass, center of mass
position and inertia tensor) is important for applications involving the ankle
joint such as inverse dynamics or stiffness measurement techniques (e.g.
Quick-release). Scaling equations relying on foot length and body mass are widely
used. However, because of the complex foot geometry, such equations may represent
an oversimplified solution. Our aim was to evaluate these approaches and propose
a new method. METHODS: Thirty-four right feet (17 Males, mean age and weight 30
years, 75 kg; 17 Females, 32 years, 61.5 kg) were reconstructed using a 3D
surface scanner and used as geometrical references. Associated inertial
parameters were calculated directly on each reference assuming a uniform density
distribution and were compared to corresponding scaling and multiple regression
estimates. Finally, an alternative method, based on multiple non-linear
regressions, was proposed considering both foot length (L) and ankle width (W).
FINDINGS: Comparisons showed that reference mass and moments of inertia were
greater than scaling predictions with mean difference up to 33 and 16% for mass
and moments of inertia respectively. The maximum standard errors of estimate for
scaled moments of inertia reached 26%. The alternative solution involving ankle
width in the equations lowered the gap with reference data (8.7% max standard
errors of estimate) for both genders. INTERPRETATION: This strategy, requiring
two simple and accessible measurements, may offer a better practicality/relevance
compromise for clinical routine use, in regards to existing scaling and
regression equations.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS