Caravaggi, Paolo

Crompton, Robin H

Goulermas, John Y

Pataky, Todd C

English

PubMed

Todd C Pataky

John Y Goulermas

Paolo Caravaggi

Robin H Crompton

Springer - Publisher Connector

New insights into stance phase foot biomechanics using pedobarographic statistical parametric mapping

BioMed Central
Journal of Foot and Ankle Research
ssOpen AcceOral presentation
New insights into stance phase foot biomechanics using 
pedobarographic statistical parametric mapping
Todd C Pataky*1, John Y Goulermas2, Paolo Caravaggi1 and 
Robin H Crompton1
Address: 1School of Biomedical Sciences, University of Liverpool, UK and 2Department of Electrical Engineering and Electronics, University of 
Liverpool, UK
Email: Todd C Pataky* - tpataky@liv.ac.uk
* Corresponding author    
Introduction
There is disagreement in the literature regarding the peak
plantar pressure correlates of walking speed. Some studies
report generalized increased pressures across the entire
plantar surface [1] while others report decreases in lateral
forefoot pressures and infer a medial shift in load with
increased walking speeds [2]. The purposes of this study
were: (a) To use statistical parametric mapping (SPM), a
high resolution statistical technique, to clarify the pres-
sure correlates of walking speed and (b) To corroborate
SPM results with those of a traditional ten-region subsam-
pling technique.
Methods
Ten subjects performed twenty trials of each of slow, nor-
mal, and fast walking in a fully randomized design.
Plantar pressure data were collected using a Footscan 3D
system (RSscan, Belgium). Walking speed was recorded
with a six camera ProReflex system (Qualisys, Sweden).
Peak pressure images were registered [3] using an optimal
rigid body transform, and then between-subjects registra-
tion was performed using an optimum affine transform to
ensure homologous structure overlap. The registered
images were analyzed using pedobarographic SPM
(pSPM), an adaptation of an established cerebral fMRI
technique [4]. A parametric mass univariate general linear
statistical model blocked SUBJECT effects and yielded a
generalized SPEED regression statistic having the Stu-
dent's t distribution. The original peak pressure images
were also subsampled over ten anatomical regions using
commercial software (Footscan 7, RSscan). These data
were analyzed using the same linear model.
Results
pSPM analyses produced smooth and continuous statisti-
cal maps that exhibited positive correlation with walking
speed over the heel and distal forefoot, but which also
exhibited broad negative correlation over the midfoot and
proximal forefoot (Figure 1A). The significance of these
trends was confirmed across subjects (Figure 1B). Sub-
sampling obscured these data, exhibiting negative correla-
tion only in the lateral forefoot, and reversing the midfoot
trend (Figure 1C).
Conclusion
pSPM analyses revealed novel information regarding
stance phase foot biomechanics, suggesting that longitu-
dinal arch collapse is actively reduced as a function of
walking speed and that such prevention may be beneficial
to propulsion, possibly through increased plantar apone-
urosis tension. The data also demonstrate, critically, that
traditional subsampling techniques can distort or reverse
statistical trends due to regional conflation, procuring
erroneous conclusions regarding foot function. Foot pres-
sure image analyses should incorporate all pixel data
wherever possible.
from 1st Congress of the International Foot & Ankle Biomechanics (i-FAB) community
Bologna, Italy. 4–6 September 2008
Published: 26 September 2008
Journal of Foot and Ankle Research 2008, 1(Suppl 1):O25 doi:10.1186/1757-1146-1-S1-O25
<supplement> <title> <p>1st Congress of the International Foot &amp; Ankle Biomechanics (i-FAB) community</p> </title> <editor>Alberto Leardini, Chris Nester, Alex Stacoff and Dieter Rosenbaum</editor> <note>Meeting abstracts – A single PDF containing all abstracts in this Supplement is available <a href="http://www.biomedcentral.com/content/files/pdf/1757-1146-1-S1-full.pdf">here</a>.</note> <url>http://www.biomedcentral.com/content/pdf/1757-1146-1-S1-info.pdf</url> </supplement>
This abstract is available from: http://www.jfootankleres.com/content/1/S1/O25
© 2008 Pataky et al; licensee BioMed Central Ltd. Page 1 of 2
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References
1. Taylor AJ, et al.: Foot 2004, 14:49-55.
2. Rosenbaum D, et al.: Foot Ankle Surg 1997, 3:1-24.
3. Maintz JBA, et al.: Med Image Anal 1998, 2(1):1-37.
4. Friston KJ, et al.: Hum Brain Mapp 1995, 2:189-210.
(A) pSPM results for an example subject, unmaskedFigure 1
(A) pSPM results for an example subject, unmasked. (B) Between-subjects pSPM results, masked at p < 0.001; data were quali-
tatively identical even after a Bonferroni correction of p < 5 × 10-5. (C) Subsampling results, masked at a Bonferroni-corrected 
p < 0.005.Page 2 of 2
(page number not for citation purposes)


Pataky Todd C

Goulermas John Y

Caravaggi Paolo

Crompton Robin H

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New insights into stance phase foot biomechanics using pedobarographic statistical parametric mapping

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