Hi all,  Bruce wrote:

>Eric;
>     You wrote:>
> > A first ray cut out does not directly cause a supination moment.  If you
> > see increased supination after the addition of a first ray cut out then
>the
> > increased supination moment probably is related to either increased
> > supination moment activity or decreased pronation moment activity.
>
>So what?!  Did the supination moment increase or not?! Did the pain go away?
>Does that make my "guess" worse than yours? Why would you not want to use a
>c/o w/ a sinus tarsi patient.  Maybe the "problematic pronation" is caused
>by the delay in sagittal plane progression, which causes a retrograde
>prolonged medial STJ position?  There are many ways to skin a cat, but why
>"wedge, or post" if you don't have too?

Eric Replies
Well, when I get sinus tarsi pain, when I don't wear my orthoses, it often
hurts worse in static stance and the varus wedge is working in static
stance.  We have long discussions on the physics of sagittal plane
progression and STJ pronation.  I still don't accept your explanation of
the physics of how FnHL creates a pronation moment.  A delay in calcaneal
unweighting is the opposite of what you would expect if pronation moment
from the ground would be increased.


> > >     How do you propose to solve these issues?  In my mind, these are all
> > >sagittal plane facilitation issues.  If you don't know where the Center
>of
> > >Pressure is, then exactly how to you know where to direct it, and w/ what
> > >degree of post will make things better or worse.  What if what you've
>done
> > >actually makes the opposite limbs function worse?
>
>Eric continues:
> > If you have a problem that you feel is caused by high pronation moment
>from
> > ground reactive force (i.e. sinus tarsi pain) then you need to increase
> > supination moment.  You don't need to know where the COP is.  You know you
> > need to move it more medial that it already is to increase the supination
> > moment.  The amount of post is guessed at.  If you guess wrong, and
> > symptoms don't reduce you add more post.
>
>Eric I strongly disagree!  You cannot know that the CoP needs to be moved
>medially in every instance.  Often patients w/ pathologic pronation have a
>midline CoP progression, and it is only a matter of equalizing the
>accelerations in both feet to eliminat their pain.  Also, at what point will
>you end your guessing about the height of the post needed?
>

This may be our point of confusion.  COP is not just a function of what is
under the foot, but also of muscle activation.  Perhaps what I should be
saying is not that you need to shift the COP more medially, but that you
need to increase the supination moment from the ground.

There is more than one source of pronation moment: the ground and
muscles.  Generally, people with sinus tarsi pain are pronation moment from
ground and they stay pronated throughout gait.

People who have late stance phase pronation often have a more laterally
deviated STJ axis and
usually don't get sinus tarsi pain.  Often these people in static stance
don't stand maximally pronated and that is why they don't get sinus tarsi
pain.  These people should also not get a varus heel wedge.

>Eric wrote:
> > Bruce, How does the treatment of one foot make the other foot function
> > worse?  Do you have an example?
>
>I'd be happy to show you several hundred f-scan movies where this is exactly
>the case.  I'm sure that Howard has thousands as well.  For instance, I had
>a problem w/ equinus on my right foot for a while.  I finally relized that I
>had my 1/8" heel lift on the wrong side and moved to my right foot and the
>early heel lift on that side disappeared.  But, now I had an early heel lift
>on the left side.  I played with this for several weeks, until I used one of
>Howards tricks...I put 1/16" ppt as a filler in my 1st ray c/o on the left
>foot.  Immediately the heel lift on the left equalized to the right side,
>and the problem was corrected.  You cannot know what you are doing w/ your
>modifications in every instance Eric!  You will eliminate the patients pain
>often enough, but just as often will set them up for future problems.
>

How do you know that symmetry is better than asymmetry?  Do you know that
the change you saw was greater than the step to step variation?  I'm glad
you equinous problem went away.  Was it Achilles tendonits?

> > What is the old saying.  If you have two explanations of the same
> > phenomenon you generally should accept the simpler one.
>
>It is called achems razor, and I dont' think it really applies to your
>explanation.

It's Ocham's razor.  I didn't know how to spell it, but you forced me to
look up the name.  I guess we will have to agree to disagree.


Cheers,

Eric Fuller

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