Jeff, Ray, Kevin and all,

Jeff wrote:
>>>This is exactly why reliable casting is important.  If a cast captures
the forefoot to rearfoot relationship (this is a complex triplane
relationship but we only measure the frontal plane component of forefoot
inversion or eversion relative to the rearfoot bisection) then the amount of
forefoot posting is intrinsic in or determined by the cast itself.  Provided
that the plaster cast additions are applied to incorporate intrinsic or
extrinsic correction (balancing), then the degree of forefoot posting
(wedging?) it determined by the negative cast.  This correction should be
consistent with the amount of forefoot deformity seen (measured) in the foot
by the clinician.<<<

Agreed, but this is only one solution, that offered by one biomechanical
theory, specifically R,O,W's conjectures: that if we bring the ground up to
the foot, i.e we post to the degree of frontal plane deformity, we negate
the need for abnormal compensation ( I know this is a simplified
paraphrasing), but this appears to ignore the other two cardinal planes (by
your own admission, we are dealing with complex triplane relationships!) and
moreover, others are now offering alternative conjectures! The prescription
writing protocol put forward by your father and his co-workers does not
appear to fit well with rotational equilibrium/ tissue stress theories (that
is not to say, that I have not had successes utilizing this protocol: I
have, and continue to use and teach it); but prescription writing within the
emerging, alternative theories seems uncertain and this uncertainty is
precisely what I wish to explore (with respect, I am not asking for
explanations of, or questioning prescription writing protocol using
traditional theory in this posting), I am familiar with prescription writing
theory using the R,O,W system, but I am uncertain of prescription protocols
using rotational equilibrium / tissue stress theories. I'm sure you will
agree, that if we are to think in terms of forces and moments, simply
correcting to the degree of deformity tells us nothing of the changes in
forces produced in the individual by the forefoot balance. But what I really
want to know is: why prescribe a 15 degree medial heel skive? Why not 20, 10
or 30 degrees?

Also, I do not wish to be too side-tracked from my more recent question,
that of the relationship between callus patterns and STJ axial position-your
thoughts please ladies and gentlemen.

Best wishes,
Simon

**************************************************
Simon K. Spooner PhD, BSc, SRCh
Lecturer Biomechanics
Plymouth School of Podiatry
North Road West
Plymouth, UK
PL1 5BY
*************************************************

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