Does a patient with a LLD due to a pelvic tilt hyperpronate on the 'long
leg' or supinate on the 'short' to compensate.
Howard R. Lester
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From: A group for the academic discussion of current issues in podiatry
[mailto:[log in to unmask]] On Behalf Of Kevin Kirby
Sent: Saturday, July 20, 2002 11:02
To: [log in to unmask]
Subject: Re: Rearfoot Varum: Does it exist?
Brian:
You wrote:
<<I define hyper [or over-]pronation as any pronation not being
generated by
the transverse plane rotations of the pelvis [see Close, The Ankle Joint
for a more complete explanation]. For example, that component of
pronation
generated from RFS I refer to as hyperpronation.>>
The definition you list above must therefore be dependent on RFS which
has
your name, "Rothbart", attached to it, Rothbart Foot Structure. RFS
means,
from what I have read of your papers, that the first metatarsal head is
elevated and inverted. Unfortunately, your definition is a useless
definition.
Any increase in pronation moments acting across the subtalar joint (STJ)
axis on the weightbearing foot will increase the ground reaction force
(GRF)
on the medial metatarsal heads, including the first metatarsal head.
This
increase in GRF plantar to the first metatarsal head will tend to
dorsiflex
and invert the first metatarsal head relative to the second through
fifth
metatarsal heads. How then, Brian, do you know that the dorsiflexed and
inverted position of the first metatarsal (i.e. first ray) is the cause
of
the "hyperpronation" and not the result of the "hyperpronation"?!
There are many etiologies of excessive STJ pronation moments in the
human
foot. Certainly an elevated first metatarsal head can be one of the
many
etiologies of excessive STJ pronation moments. However, to suggest that
any
"pronation generated from RFS" should be termed "hyperpronation" makes
it
therefore impossible to define "hyperpronation", using your definition,
since we can't assume that all pronation is caused by a dorsiflexed and
inverted first metatarsal!
This would be like saying that anything that makes a running shoe lean
into
eversion is caused by a thinner medial midsole than lateral midsole.
However, a foot with excessive pronation moments acting on it may also
make,
over time, that medial midsole of the running shoe to be thinner
medially
than laterally. Now when you look at the shoe after a year of running
in
it, and the medial midsole is more thin than the lateral midsole, and
the
shoe leans into eversion, can you be absolutely sure that a pronating
foot
did that to the shoe? Of course not. It is also possible that the
medial
midsole was thinner than the lateral midsole when it was shipped from
the
shoe factory. Therefore, your classification of feet into RFS based on
the
position of the first ray does not, in any way, tell us whether the
abnormal
motion or position which that foot has at the STJ is the result of the
elevated first ray or has been caused the abnormally elevated first ray.
<<I evaluate STJ NP in a closed kinetic chain, patient standing weight
on
both feet. Using motion-palpation technique, I determine NP and measure
the foot at that point [see Rothbart 2002 Medial Column Foot
Systems ........ for a more complete explanation].>>
Which joint do you palpate to determine the subtalar joint neutral
position?
<<I still question the existence of Rearfoot Varum. I am very familiar
with
the Podiatry literature on the subject but I have seen no scientific
papers
discussing its etiology [from an Embryological point of view it would be
very difficult to argue its existence].>>
As Ray pointed out, you may question the existence of rearfoot varus,
however, you may also, just as well, question the existence of the two
things we walk on every day, which most of us call "feet". Rearfoot
varus
has already been defined in the podiatric literature for over the last
thirty years just as "feet" have been defined in the English language
for
many more years. I am confused, do you question the existence of an
inverted posterior bisection of the calcaneus when the STJ is in the
neutral
position which would be "rearfoot varus"? I see it every day in my
practice....along with five digits on each foot.
Sincerely,
Kevin
*****************************************************
Kevin A. Kirby, DPM
Assistant Clinical Professor of Biomechanics
California College of Podiatric Medicine
Private practice:
107 Scripps Drive, Suite #200
Sacramento, CA 95825
USA
Voice: (916) 925-8111 Fax: (916) 925-8136
e-mail: [log in to unmask]
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