Today’s post begins to explore the demands of a supinator. Who are these patients? What do they need specially prescribed in their orthotic devices? When is supination bad when we were taught: pronation is bad, supination is good. It is all about the timing of when we supinate. As the diagram below shows that roll to the outside as the foot hits the ground, supination is not helpful to smooth body mechanics when it occurs at heel contact. Supination in midstance and propulsion is generally good if not excessive (like in a spastic achilles). What should happen at heel contact with the ground? At this moment in time, the whole lower limb is internally rotating with femoral, tibial, and hopefully talar internal rotation.This internal limb rotation is tied to subtalar joint pronation closed kinetic chain with talar internal rotation (adduction) and plantarflexion, on calcaneal eversion. The foot is becoming that mobile adapter we need to navigate the ground, dance floors, and stairs (to name a few). Supination at this time ruins that ability to be a mobile adapter. Supination also ruins the inherent shock absorption we get in the motion of pronation (which we also lose when we are maximally pronated–for another discussion). This calcaneal inversion, subtle in many patients, is linked closed kinetic chain to talar external rotation and dorsiflexion. If you understand that humans have adapted this motion of contact phase pronation to minimize stress produced by their mobility, then supination at the wrong time will add stress somewhere. That somewhere presents in our patients at times as ankle pain, stress fractures, knee or hip pain, even low back pain. There will be a further discussion of this in an upcoming post.
When I was a student, one of my biomechanics instructors, Dr John Marzalek (pardon if I mis-spelled), was explaining to us that we can see contact phase pronation better than supination. I have validated that statement in my years of practice. This was re-enforced by Dr Michael Burns, owner of Burns Orthotic Lab, saying the human eye typically only sees 5 degrees of motion or more. So if there is two or three degrees of contact phase supination, it may appear to you as no motion. So, in gait, you watch the heel move, and it doesn’t, where it doesn’t have to look inverted either to invert (genu valgum patients invert on the everted side of verticality). So, many times in gait, we will see the pattern of no heel motion, yet lateral motion of the lower tibial and knee. Here is a great place to look for it. I, however, do see contact phase all the time because I am looking for it. If you are not looking for it, you will never see it (sorry I can not tell you the reference for that famous quote. I think how you can appreciate the 3 common names for supination problems: over supination, under pronation, and lateral instability.
They mean the same thing, but I hope the phase “underpronation” which came out of the running world, means more to you. In teaching the store clerks about this problem, which was just as bad as pronation, but you probably won’t see it, they called in “underpronation” in contrast to the “overpronators”.
As we explore this problem of contact phase supination in these upcoming posts, know that there are so many options or modifications we can do to your orthotic prescription. However, you need to look for it, and recognize it. Since I developed the Inverted Orthosis, I had to get real good at recognizing patients that I iatrogenically made into supinators. The patient may or may not be able to help you. There are so many fixes for this: orthotic modifications, peroneal strengthening, limb single leg balancing, shoe types, terrain selection, and even gait retraining for some. See you next week.
Lateral Heel Roll Seen In Supinators
