On Thu, 2 Dec 2004 16:58:39 -0800, Kevin Miller <[log in to unmask]>
wrote:
>Hello Tony, others,
>
>As I alluded in the previous post, motion of any sort is a reciprocal
symphony of afferent and efferent signals modulated by the cerebellum.
Pressure and positional data from feet must correlate with data from other
from other receptors and the vestibular system in order for smooth gait to
occur, forcing the COM to act as Kevin K. described in his response to
this topic. Adaptations are made in the cerebellum for variations from
the norm. (The orchestra knows the arrangement and the symphony can
proceed even with not so minor changes in the score. Everyone recognizes
the melody, and only the practiced ear hears the change made by the
conductor and musicians.) For instance, try walking with a very heavy
object held in an outstretched arm. The position of your COM is shifted
towards the mass. Your trunk must counter to bring the COM back to a
function position. Your gait will be altered, but you can still walk.
All of this is obvious. But what happens when I created sensory
> deprivation? For instance, if I imobilize your hand for 6wks, your two
point discrimination will suffer, as will your fine motor coordination.
(The new Cellist is a little taller and wider than the old one......the
line of sight to the conductor is broken for those behind him. They still
play, but just a little out of sync. We still recognize the melody and
arrangement, but it is not quite as pleasing.) Similar effects will occur
if I simply restrict ROM. Wearing a brace that prohibits pronation and
supination and allow only one plane of motion from the elbow distal, for
instance. Apply this to the foot. Now change in coordination of
movements has a greater effect. Stability of the organism suffers because
the COM is affected, not simply arm positioning. At some level, we can
predict a degree of these effects simply by walking on non-varying
surfaces. Wearing "proper shoes" should produce a greater effect. But as
long as there is an impulse getting to the spine, and some
> form of pressure registered by the foot, the effects should not be
noticable. Except..... A child just learning to walk, or someone
recovering from a stroke or other injury that keeps then non-ambulatory
for a while..... maybe a child who has just begun wearing shoes. (You can
think of a myriad of possibilities, I am sure.)
>
>Enter the silicone orthoses. They create an interesting paradox. On one
hand, they dampen the impulse delivered to the spine. But the properties
of silicone are such that it just might respond similar to walking on
natural ground. The result? More sensory input..... data that has been
missing for the cerebellum. (The Cellist has lost a little wieght and
found a shorter chair.) It doesn't take very long for the cerebellum to
make use of this and restore stability. (And the symphony is flawless once
again.)
>
>Regards,
>Kevin M
>
>Anthony Achilles <[log in to unmask]> wrote:
>Kevin, Kevin and Norman,
>Could you please elaborate on the subject in regard to sensory perception
and stability in gait. I have found myself, that, even by introducing in a
child a silicone foot orthoses improves stability with little mechanical
intervention. Your thoughts around this subject and anyone else's would be
greatly appreciated
>regards
>Tony Achilles
>
>________________________________
>
>From: A group for the academic discussion of current issues in podiatry
on behalf of Kevin Kirby
>Sent: Thu 02/12/2004 17:51
>To: [log in to unmask]
>Subject: Re: Changes in base of gait related to orthoses
>
>
>Clive and Colleagues:
>
>Clive wrote:
>
><
>I saw an example of this yesterday when teaching essential biomechanics
to a group of physiotherapists. In the process of the day I earmarked one
of the physios as a good subject for me to use to demonstrate examination
and treatment with chairside orthoses. She had B/15 degrees forefoot
valgus/10 degreees rearfoot varus/ functional hallux limitus. When she
walked the building shook at heel strike and she had a base of gait that
was, at 30 cm, the same as her base of stance. She walked with
a "stomping" gait which looked agressive. There were no symptoms other
than residual pain from a 3 month old right ankle injury.
>
>I made devices as follows; B/rearfoot 15 degrees varus/ forefoot 5
degrees valgus/ kinetic wedges. By the time she had walked 10 metres
wearing the orthoses the base of gait has reduced to about 5 cm, there
were some postural changes which she said felt good, the heel strike was
not heavy and the walking suddenly was less agressive and stomping, the
ankle pain had gone.
>
>All that being as it may, it is not that unusual - except for me, the
huge reduction in the base of gait. I can't work out why that should
happen (and I have seen from a less wide base it other patients who have
forefoot valgus).
>
>Is it that the lateral instability of the feet demands a wider base of
gait for more stability in walking? When people are drunk they appear to
use a wider base of gait as a help in not falling down, is this similar?
Is it a sensory-postural-motor compensation for the lateral instability
arising from the valgus forefoot?>>
>
>I have been thinking of writing a newsletter about this phenomenon for
some time. I have also noticed this effect of a narrowing of the base of
gait in feet with "rigid forefoot valgus". Interestingly, this narrowing
of the base of gait is even more pronounced in many patients with multiple
sclerosis, when a forefoot valgus wedge is added to shoe insole.
>
>Here is my short synopsis of my theory that I will publish likely in the
next few months in a coming Precision Intricast Newsletter. Bipedal gait
requires that the center of mass (CoM) always stay within the medial-
lateral boundaries of the center of pressure (CoP) of the feet in order to
allow bipedal walking gait stability. If the CoP is more medially located
on the plantar foot, such as from a relatively rigid plantarflexed first
ray, then the individual must abduct their hip more during walking in
order to bring their CoP more lateral to the CoM in order to improve
bipedal stability during walking gait. Using a valgus forefoot wedge will
move the CoP more lateral which will then not require the individual to
abduct their hip as much to move their CoP to a more lateral location
relative to their CoM in order to improve bipedal stability during walking
gait.
>
>Forefoot valgus wedges will also increase the stride length compared to
forefoot varus wedges in most individuals, as Simon Spooner, Tony Achilles
and Chris Nester have been shown on their own feet. However, this is
another theory, maybe for some other paper or newsletter.
>
>Cheers,
>
>Kevin
>
>**************************************************************************
**
>Kevin A. Kirby, DPM
>Adjunct Associate Professor
>Department of Applied Biomechanics
>California School of Podiatric Medicine at Samuel Merritt College
>
>Private Practice:
>107 Scripps Drive, Suite 200
>Sacramento, CA 95825 USA
>
>Voice: (916) 925-8111 Fax: (916) 925-8136
>**************************************************************************
**
>
>
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Dear Kevin
Chaning the motion of the Talus changes the whole way the foot and thus
posture works.
Some 6 months ago I had a patient aged 58, who has a medical and surgical
history you don't want. This includes two strokes and 6 operations for
bowel strangulation, just for starters.
He suffered a cereberllar stroke that left him profoundly vertigous, even
when lying down.
This stroke happened when he was 28 some 30 years ago.
Nothing has been found to cause this vertigo. H has had the colorific test
for vertigo three times. I doubt anyone who has had this terrible test
would go through it again, he did.
I mobilised his feet and he has been able to stand still without motion
and with closed eyes for the first time. This has now lasted the whole 6
months.
This may be hard to beleive, but I have it on video.
I also have recently mobilised the feet of a man extremely affected by
Parkinson's disease. He now has better stability and has returned to golf
and is pleased as punch. This has led to talks with his specialist
neurologist and we may trial performing same pre and post visits to the
vertigo clinic at St. Vincent's Hopsital Sydney to see if this helps these
poor souls.
An Aside: My son is 6 foot 10 and hits the golf ball a mile. He has
overpronated feet courtesy of his mother. He can hit a ball over 300
metres from the tee. If he does not wear his orthotics he looses between
40 and 45 metres off the tee.
There is no doubt in my mind that just returning the talus(not subtalar
neutral) towards neutral is all that is needed for the cerebellum to
remove the rubbish imputs in the kinetic chain and thus with less garbage
(IN) there is less garbage (OUT) and a better result is achieved.
Regards,
PAul Conneely
www.musmed.com.au
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