Hi all,

At the end of an excellent post Kevin wrote:

>Now we add a medial heel skive foot orthosis that exerts 33.0 Nm of STJ
>supination moment to the foot, then the floor of the sinus tarsi of the
>calcaneus will still be exerting 0.5 Nm of STJ supination moment on the
>lateral process of the talus, but this has greatly reduced the patient's
>pain in the sinus tarsi, since the interosseous compression force has
>reduced.  However, this orthosis has not moved the STJ out of the
>maximally pronated position even though the foot orthosis has relieved the
>patient's symptoms.  The moments have changed, with no change in motion,
>but symptoms have resolved.  Kinematics in this case would be useless to
>provide us the answer as to how the orthoses cause the pain to be resolved.
>
>This is why motion analysis is, by itself, will never give us good
>information regarding how foot orthoses relieve the painful symptoms in
>our patients.....because there are too many maximally pronated feet!

I agree with Kevin has said and would like to add one thing.  If you do see
supination of the STJ with Kinematic analysis then you do know that enough
supination moment was added to overcome the pronation moment from other
sources.  So, if you have a patient with sinus tarsi pain and without the
orthosis there is no supination and with the orthosis there is supination
then you would expect a reduction in symptoms.  What we are saying here is
that measurement of motion can be useful, but it is not as good as
measurement of moments for explaining why symptoms reduce.


Cheers,

Eric Fuller

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