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Novel Biomechanics Lab
04-17-1996, 08:36 PM
Dear List Members

Very often we receive questions from people working with plantar pressure
distributions, along the lines of:

a) what areas of the foot should they be looking at, and why?
b) what parameters should they be considering, and why?

I realise that the answers to these questions will probably depend on the
particular disease of interest, or the particular surgical procedure that may be
being compared pre- and post-operatively. However, are there any guidelines or
reasonings behind which areas of the foot to analyse for different cases?

Take diabetes, for example. (Of interest to me at the moment, as I am in the
process of trying to analyse a group of diabetic feet!) Several 'masks' of the
foot have been used in the literature, ranging from that used by Cavanagh which
includes the medial and lateral heel, the medial and lateral midfoot, the
medial, lateral sides and centre of the forefoot, the hallux, the second toe,
and the remaining toes; to a relatively simple masking of the foot including
just the heel, midfoot, forefoot and toes (sometimes!)

Taking into account the time involved in the past in generating the masks and
analysing the data, what is considered necessary?

Also, we (novel) are now in the position of being able to generate automasks, so
that we can draw one mask over one footprint, and then this mask is
automatically rotated and transformed to fit any other footprint, small or
large. Such a mask can either be drawn by the user, or a list of masks can be
provided that will be automatically applied to any footprint. For example, one
just defining the heel, midfoot, forefoot and toes, or a more complex mask such
as that used by Cavanagh.

But.....there needs to be good scientific grounds for choosing the divisions of
the foot. For example, where should the midfoot be defined? Between what
percentages of the foot length? How should the forefoot be separated? Should we
be looking for anatomical landmarks or should we be simply dividing the foot
using numerical algorithms (maybe as done by Rossi W.A. (1992) Podometrics: A
new methodology for foot typing. Cont. Pod. Phys.; Nov: 28-39.) One advantage of
using purely numerical divisions of the foot is that it is not subjective. But
do people want the opportunity to define there own divisions? Or, should we
standardise these divisions?

Secondly, what parameters should we be considering when analysing the plantar
pressure distribution? The maximum pressure only? The pressure-time integral?
The force-time integral? The contact area? The time of loading; above a certain
pressure threshold, maybe? And in which case, what pressure threshold? How can
this be defined? The evolution of the loadbearing of the foot? The gait line?
The gait line coordinates? The progression of the gait line? The velocity of the
gait line? The differential loading of the medial and lateral sides of the
foot?

All these parameters can be analysed but which are important, or relevant?

We are also intending to put a new database software package on the internet, so
that everybody who is interested in participating in a data-pool can dump
pressure distribution data into the database. This would then be accessible to
everybody. It is anticipated that all the data would be clearly described so
that different groups of data could be carefully selected, e.g.age-matched
normal controls, patient data from certain deformities, diseases or
malfunctions, and of course the type of pressure distribution measuring
equipment. This should help researchers in providing a large pool of accessible
data.

What do people think about this? How would it need to be organised? Could it
work? What sort of data are people looking for?

As is the normal custom, I will post a summary of any replies that I get. And
thank you in advance.

Anna Hayes

P.S. If anybody wants any information about the software available to do this
sort of analysis, please contact me here via email, or in Munich. Address and
telephone number below:
Dr. Anna Hayes
Biomechanics Research Laboratory
Novel GmbH
Beichstrasse 8
80802 Munich
Germany
Tel: 0049 89 390102
Fax: 0049 89 337432