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Ton Van Den Bogert
04-15-1993, 06:01 AM
Dear Biomch-L subscribers,

Richard Smith wrote:
>At the Faculty of Health Sciences, The University of Sydney we are conducting
>studies on the mechanics of the foot. One of the major problems in comparing
>intra and inter-subject trials is the lack of a definition of neutral alignment
>of the rearfoot particularly in relation to inversion and eversion. Has anybody
>had experience with this and would like to share their findings?
>At the present time we are using the midline of the posterior aspect of the
>calcaneus and lower one third of the shank to define inv/eversion neutral and
>foot flat and vertical alignment of the malleolus and lateral epicondyle of the
>knee for plantar/dorsiflexion and midline of calcaneus to second mtp for ab/
>adduction.

I have used the following procedure: the subject is asked to
stand in the anatomical position, with equal weight on both feet.
The lateral malleolus and head of the fibula are vertically
aligned. The A-P axis of the foot (defined as the line through
center of the calcaneus and center of the second toe) is aligned
with the A-P axis of the trunk. The resulting orientation of the
ankle joint complex is defined to be the 'neutral', for each of
the three 3-D joint angles. It seems to be quite reproducible,
although I have never quantified that.

The main difference between this procedure and the one mentioned
by Richard is that my neutral position for in-eversion is not
defined by anatomical landmarks. Instead it is defined as the
orientation during a standardized weightbearing situation. I
find this more convenient, and it is good enough for my purpose.

-- Ton van den Bogert
Human Performance Laboratory
University of Calgary, Canada