Trevor, you wrote:  >Taking your above statement literally indicates that as
long as the posterior bisection of the calcaneus is vertical that the stj is
neither supinated or pronated and the talo-navicular joint is congruent i.e.
that in this "vertical" position the foot is stable. This theory is
explicitly flawed if one considers the following;
Say we have a patient (to make things easy with equal bilateral BMX
stuctural anomaly) 8deg. tibial varum & 4deg. rearfoot varum non weight
bearing [apologies to all who poo poo measuring ;-)] In relaxed mid-stance
the calcaneus rests vertical.
By Root et al's figuring this calcaneus displays one of the criteria of
normalcy (or am I misunderstanding something?).

Jeff replies:  You can not use only one of the criteria for normalcy to
determine if the foot is normal or abnormal by Root standards.  Trevor, you
seem to be using Root theory to suggest that Root theory is invalid.  If
Root's criteria for normalcy (ideal) are invalid, then there really is no
such thing as tibial varum and rearfoot varus because such deformities
(conditions) are concepts within the paradigm in which they exist.  Only by
the establishment of the criteria for normalcy and the resulting calcaneal
bisection technique can deformities such as rearfoot varus be defined.

In Root's criteria for normalcy, the distal third of the leg is vertical,
the posterior bisection of the calcaneus is vertical, and the plantar plane
of the forefoot is perpendicular to the rearfoot bisection, WHEN the STJ is
in the neutral position and WHEN the MTJ is fully pronated.  The error in
your argument is that you seem to be applying abnormal conditions (8deg.
tibial varum & 4deg. rearfoot varum) to a vertical calcaneus and implying
that we might have a normal foot according to Root theory.  Root theory
would describe your example as anything but a normal condition.  It was
Root, who by measuring the frontal position of the posterior surface of the
heel, coined the term rearfoot varus.  Rearfoot varus can be defined as a
condition in which a) the ratio of calcaneal inversion relative to calcaneal
eversion exceeds 2:1 when measured in the frontal plane or b) when the STJ
is in the neutral position, the bisection of the posterior surface of the
calcaneus is inverted to the distal 1/3 of the leg.

Root stated in his text that variations in morphology are common and only
the practitioner can deem when such variations are likely to be pathological
in nature and warrant treatment.  It is interesting that practitioners
outside the U.S. use a much higher percentage of inverted and Blake type
orthoses than practitioners within the states.  With all the talk of Root's
theories, it seems that there is much more effort by others to reduce or
prevent STJ pronation than Root believed was necessary.  He believed that
STJ pronation was an essential aspect of healthy locomotion and only
attempted to reduce pronation or the extent of pronation when it was deemed
pathological in nature.

Respectfully,
Jeff Root

----- Original Message -----
From: "Trevor Tillotson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, May 14, 2001 3:46 AM
Subject: Re: Static stability of Calcaneus


> Kevin
>
> You wrote:
>
> Sent: Monday, May 14, 2001 9:13 AM
> Subject: Static stability of Calcaneus
>
>
> > Colleagues:
> >
> > If we accept that a definition of static stability of an object is as
> > follows:
> >
> > "the property of a body that causes it, when disturbed from a condition
of
> > equilibrium or steady motion, to develop forces or moments that restore
> the
> > original condition." (Webster's New Collegiate Dictionary, G. & C.
Merriam
> > Co., Springfield, Massachusetts, 1975.),
> >
> > then where do the forces or moments originate from that impart stability
> to
> > the calcaneus in relaxed bipedal stance?
>
> This a subject that has been discussed before. Hard to simplify isn't it!
> Here's my simplification.
> If we cosider the turning moments passing through the talus, mtj &
calcaneus
> via the stj (taking into account its triplanar function) as resulting, in
> part, with the transverse plane relationship of the stj at HS, the
resultant
> force will create a turning moment. This usually results in pronation of
the
> foot about the stj until, in relaxed bipedal stance, a resistant force
> either slows down, and eventually stops, the movement or EOROM occurs. As
we
> know from BMX pathology (fou & tissue trauma) the calcaneal architecture,
> its self, is often unable to provide its own level of equilibrium in order
> to stabilise its self, even to a vertical position at rest. The resultant
> lack of stability resulting in the pathology we see.
>
> >
> > What I am getting at is this:
> >
> > One of Root, et al's eight Biophysical Criteria for Normalcy (Root,
M.L.,
> > W.P. Orien , J.H. Weed and R.J. Hughes:  Biomechanical Examination of
the
> > Foot, Volume 1.  Clinical Biomechanics Corporation, Los Angeles, 1971,
p.
> > 34) is as follows:  "D.  The bisection of the posterior surface of the
> > calcaneus is vertical."
> >
> > Even though Root et al meant these Biophysical Criteria for Normalcy to
be
> > representations of ideal physical relationships of the osseous segments
of
> > the foot and leg for the production of maximum efficiency during static
> > stance or locomotion, does anyone **still** believe that the vertical
> > calcaneus is an ideal structural alignment of the calcaneus in static
> > stance, and why?
> >
>
> This part of the Root paradigm has always confused me as it does not take
> into account BMX pathology either intrinsic to or extrinsic to the foot.
The
> Root paradigm also states (my words) that a condition of stability exists
in
> the foot when the stj is neither supinated or pronated (ie. is in
"neutral")
> and when the talo-navicular joint is in a state of congruency.
> Taking your above statement literally indicates that as long as the
> posterior bisection of the calcaneus is vertical that the stj is neither
> supinated or pronated and the talo-navicular joint is congruent i.e. that
in
> this "vertical" position the foot is stable. This theory is explicitly
> flawed if one considers the following;
> Say we have a patient (to make things easy with equal bilateral BMX
> stuctural anomaly) 8deg. tibial varum & 4deg. rearfoot varum non weight
> bearing [apologies to all who poo poo measuring ;-)] In relaxed mid-stance
> the calcaneus rests vertical.
> By Root et al's figuring this calcaneus displays one of the criteria of
> normalcy (or am I misunderstanding something?). I understand all of the
> other (Root et al) Biophysical criteria for Normalcy and that the vertical
> calcaneus is meant to be associated with those when viewed in the "normal"
> foot/leg. I also understand that most USA practitioners will (in most
> cases????) balance the calcaneus to vertical believing this to be the most
> stable position for it in relaxed mid stance, and this baffles & concerns
> me. If one takes into account my above scenario, this patient would have
> pronated a total of 12deg. until the calcaneus comes to rest (for whatever
> reason - eorom?), in motion this could be more (stj motion allowing). The
> neutral position of this persons stj is with the calcaneus balanced at 12
> deg. varus in relaxed bipedal mid stance.
>
> > One of the reasons why I ask this question is that I believe that these
> > concepts are still being taught as part of the biomechanics curriculum
in
> > all of  the podiatry colleges in the US.  I would be interested to know
> what
> > some of the other international biomechanics educators are teaching
their
> > students in this regard (Craig, Simon, Karl, Stephen, etc.).  Is there
any
> > mechanical reason why a vertical posterior surface of the calcaneus
should
> > be more stable or more "ideal" structurally than a calcaneus which is,
for
> > example, 2 degrees inverted or 4 degrees inverted?
> >
>
> I would have no hesitation in balancing the calcaneus of the above
> hypothetical patient, at least 12 degrees in varus, perhaps even more
> depending upon BMX findings, pathology & activity. I have been stabilising
> the calcaneus to the "actual" neutral position from my BMX assessment
> measurements for nearly 20 yrs (before the term "inversion cast" was
coined)
> and taught this method of rearfoot balancing when teaching biomechanics at
> the NZ School of Podiatry in the early-mid 80's. I think we were teaching
> this way , probably before most other places because we misinterpreted
what
> Root et al were saying. By calculating the frontal plane rearfoot AND leg
> measurements, relative to the sagittal plane, non-weightbearing & relating
> them to the frontal plane weightbearing measurements (relaxed mid-stance &
> neutral mid-stance) we understood that we were calculating the "over-all
> neutral" position of the calcaneus relative to the mid sagittal plane. We
> never could understand why we were reading in the literature of the day
that
> functional orthoses should aim to balance the calcaneus to vertical in
> relaxed mid-stance. If this is still being taught in the USA, when can we
> come over to do a few lecture tours ;-)
>
> > Please, all replies are welcomed.
>
>

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