In a message dated 5/17/99 3:15:51 PM Pacific Daylight Time, [log in to unmask]
writes:

Jeff wrote to Bob

> If an individual has a foot type that exhibits very little compensation in
>  relaxed stance, then I suspect that one might see very little positional
>  change on X-ray during relaxed stance while the individual is wearing an
>  orthosis.  Conversely, I suspect that feet with structural conditions that
>  are compensated for during relaxed stance will demonstrate appreciable
>  differences when X-rayed both with and without orthoses.  Since positional
>  changes produced by orthoses such as the frontal plane position of the
>  calcaneus or talar position are visible to the naked eye, why shouldn't we
>  be able to confirm this on X-ray?

I not sure of what you mean by a foot that exhibits little compensation.  Do
you mean a foot that pronates little from neutral position.  Or do you mean a
foot that is maximally pronated and compensates little because there is no
further range of motion in the direction of pronation.  Classical theory, as
I understand it assumes that compensation occurs from neutral STJ position.
Almost all feet never see neutral position in normal gait.  (McPoil TG, et
al.  The relationship between static lower extremity measurements and
rearfoot motion during walking.   J Orthop Sports Phys Ther. 1996
Nov;24(5):309-14.)  I question the assumption that feet compensate from
neutral position.  A maximally pronated STJ that stays maximally pronated
would be a situation where there is little change in position of the bones on
x-ray.  I think it would be important for you study to note if range of
motion was available in the direction of pronation before and after standing
on the orthosis.  (Can the calcaneus evert?)  Or you could look for signs of
STJ position on x-ray.  (e.g., the lateral process of the talus in the floor
of the sinus tarsi.  A.k.a. the Kirby sign.  Although, I've never heard Kevin
call it that.)

>
>  It is conceivable that an orthosis may alter the range of motion of certain
>  joints during gait (increase or decrease ROM) or otherwise eliminate
>  symptoms without producing an appreciable change in the osseous relation
>  during relaxed stance.  Therefore, though one may exist at times, I do not
>  intend to suggest a linkage between symptom response and our ability to
>  alter position during resting stance with an orthosis.
>
>  I do however believe that we should be able to demonstrate that certain
>  osseous conditions will produce predictable positional changes when treated
>  with functional orthoses.  I welcome any input from list members to assist
>  us in putting together a more meaningful presentation.
>

A good question is what percentage of the time does a rearfoot varus (or some
other osseous condition) change its position while on top of an orthosis.
(Does a rigid forefoot valgus end up being in a more pronated position of the
STJ with a forefoot valgus orthosis balanced to perpendicular?)  I think
these are better questions than do position changes exist.  Another question
is how often are symptoms relieved without osseous changes?  Someone has
already reported one example where symptoms were relieved with little osseous
change.  If it were a significant number it may make you rethink the idea
that orthoses work by changing osseous position.

Respectfully,

Eric Fuller



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