Oh Great Chipster!
To have gotten a reply from thee! I am so honored! But beyond that - I long ago, (and
some say, far away) developed a modification to both the Blake and the medial skive
proceedures that solves some of the difficulty I came up against with their mutual
standard approaches. I have spoken of this modification many times - I call it the
Valmassy modification, because Ron was the first clinician to be willing to try it out
with his patients, (and because I couldn't very well call it the Quasimodo
modification, now, could I?).

This mod was developed in response to what seemed an obvious problem with both
approaches, to whit (always wanted to say that), when the cast is either inverted, for
the Blake, or the medial anterior aspect of the plantar heel of the cast is shaved and
re-shaped, as in the medial skive, the volume and width of the heel cup is
significantly changed. In fact, it is made narrower. Any resultant orthoses, assuming
the standard lateral expansion amount and shape is employed in either case, results in
a heel cup that is too narrow for the patient. This is easy to see if you view the cast
posteriorly, then invert the cast, after drawing a heel cup depth line aroung the
circumference of the heel, say, 20 mm.

So it is clear that the standard approach to lateral expansion is insufficient for
either of these cast correction approaches. But the problem extends to more than width
and volume - it also involves the shape of the lateral expansion. The act of skiving or
inverting the cast in effect "lifts" (I know, not very scientific, but it is true) the
medial aspect of the heel. As the calcaneous is, at least the last time I looked, a
rigid bone, then any change in elevation along one side of that bone must create an
opposite effect on the other side of that bone, i.e., it "drops". So big deal, you say.
What of it, you snarle. No skin off my back, you sneer. Well, maybe you didn't do all
those things.

If the lateral side drops as the medial side is lifted, then the lateral expansion must
respond to that basic fact. The standard shape used for lateral expansions creates
resistance to what the orthoses is attempting to accomplish along the medial aspect. By
using a Valmassy modification, the orthoses can usually accomplish the same amount of
control with a lesser degree of cast correction overall. To get an idea of this shape,
simply take a standard Root-style orthoses, viewed posteriorly, and rotate into
inversion. Observe the lateral heel against a verticle bisector. Now, increas the heel
cup depth along the lateral side while maintaining that shape. Wallah, as they say in
India.

Oh, I do go on. I'd be glad to show you this at the seminar in October. Glad you'll be
on board.

Latte, as they say in California.
Notty Bumbo

dorsalis wrote:

> Notty Bumbo wrote:
> >
> > Dearest dorsalis,
> > To respond to your response to the call for response from the previous
> > respondent:
> >
> > Your suggestion while I believe biomechanicaly astute may have at least one
> > negative result, to whit, excessive lateral pressure along the heel, causing
> > significant soft tissue compression as the heel actively presses against the high
> > lateral flange required to maintain such a foot on such a device. I find that
> > soft tissue complications are often overlooked consequences where more extreme
> > corrections are required. Most soft tissue supplements, such as poron or
> > neoprene, fail to provide more than temporary protection, as the shear forces
> > present at this juncture are quite high. This observation doesn't preclude
> > application of corrections as described, it is merely a caution.
> >
> > Notty Bumbo
> > PS, Chip, Hope to see you in October at the PFOLA/CCPM Biomechanics Conference.
> >
> >
> Dearest Most Honorable Quasimodo Notty
>
> I was just invited to Lx at the PFOLA mtg by Piedmont Labs here on the
> East coast and look forward to hearing from B'wana Paul about what and
> when (within the context of the agenda.  I have the dates).
>
> Your concern about excessive lateral pressure along the heel is duly
> noted.  I was surprised in lieu of this to see your own suggested
> solution to this problem:
>
> >Ray, I would balance to 6 degrees FF psition, then apply a medial skive at
> >rearfoot, with attendent lateral heel modification to allow for proper
> >expansion re: lost volume from skive. This should effectively re-shape rearfoot
> >to a near-verticle position, if shaped properly.
>
> In our attempts to do medial skiving within the school lab, we have
> found more problems with excessive lateral pressure then when we attempt
> to impart rearfoot inversion with a Blake device.  I had attributed this
> control parameter in the Blake device to the remarkable forefoot
> balancing which accompanies the Blake modification and serves to assist
> in alleving lateral slippage in the plate.  Certainly, our patients with
> this particular type of foot have been more happy with the Blake,
> although certainly, the Kirby Medial Skive has its place, especially
> with Tibialis Posterior Dysfunction Syndromes.
>
> Now, I realize that you had a lot of experience with Rich Blakes
> earliest attempts out West, and I had been quite impressed with the
> plaster work on Blake devices you all did at Pro Lab.  But, if you only
> skive the heel on this type of foot, won't you be bringing the forefoot
> up without concomittant additional intrinsic/extrinsic posting?  If the
> forefoot truly loads under the lateral column and compensates under the
> medial column (5th theorem), then anything which inverts the rearfoot
> also inverts the forefoot by an equal number of degrees. Without
> additional intrinsic/extrinsic posting, you will still have the
> structural forefoot varus only partially compensated.  Whereas, with the
> Blake, by actually inverting the rearfoot THEN balancing to an inverted
> rearfoot position that is at about 6 degrees greater then neutral, there
> is loading and resistance between forefoot and rearfoot.
>
> Ray, why not try both?
>
> Chip S.
>
> ***********************************************************************
> > ************************************************************************
> > Charles C. Southerland Jr. D.P.M., FACFAS, FACFAOM
> > Professor of Podiatric Orthopedics & Biomechanics
> > Barry University School of Graduate Medical Sciences-Podiatric Medicine
> >
> > email- [log in to unmask] OR [log in to unmask]
> > snail mail - c/o Barry University School of Grad. Med. Sci. - POD
> >                  11300 NE 2nd Avenue
> >                  Miami Shores, FL. 33161
> >
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