video gait analysis and electromagnetic motion
tracking. Results so far have indicated a weak
relationship between the static FPI measurement
and dynamic foot function [9,10] . Electromagnetic
tracking of the ankle joint complex in a small
group of participants demonstrated the FPI
predicted 41% of variance in ankle joint complex
inversion and eversion [9] . The study involved
FPI being manipulated through use of inverted
or everted wedging and the resulting ankle
joint complex gait dynamics being correlated
to the contrived FPI during midstance. Whilst
this demonstrates relatively poor predictive
capacity, it is of greater strength than similar
investigations of alternative static measures [5,11] .
In relation to the midfoot, 45% of variance in
minimal navicular height and 13.2% variance in
navicular drop were found to be predicted by
the FPI suggesting poor prediction of forefoot
motion however, this is restricted to motion
measured with two dimensional techniques [10] .
Due to the limited number of studies
investigating the use of the FPI as a predictor of
dynamic function the results are inconclusive.
The purpose of this study was to determine and
compare the strength of correlation between
static foot position, as determined by the FPI,
and maximum dynamic three dimensional
frontal plane rearfoot eversion in both pronated
"Historically, research into the effect of foot orthoses and footwear on
dynamic foot function has been hampered by difficulty in reliably classifying
foot type for inclusion in studies, possibly contributing to subject-specific
findings and lack of homogenous response to specific orthotic styles..."
and normal foot types. Overall predictive ability
of the total FPI score for dynamic rearfoot
motion was investigated. Planar dominance of
subtalar joint motion has been linked to subtalar
joint axis position, specifically the pitch of the
axis, with increased frontal plane motion of the
rearfoot thought to be associated with a lower
pitched axis [12] . The correlation between the
score for the rearfoot frontal plane components
of the FPI measurement and pure frontal plane
motion of the calcaneus was calculated to
determine the strength of relationship between
static frontal plane dominance at the subtalar
joint and dynamic frontal plane motion.
Methods
This project was undertaken in the
Biomechanics Department of the School of
Exercise and Sports Science, Faculty of Health
Sciences, Cumberland Campus of the University
of Sydney. Ethical approval was obtained from
the University of Sydney's Ethics Committee.
Current Pedorthics | May/June 2019
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