Why do orthotic posts focus on frontal plane angulation?

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Y'all, my main man wrote in another thread (listening to too much Run DMC tonight):

Why do orthotic posts predominantly focus on frontal plane angulation? Seem to recall something from the distant past called a triplanar wedge?

 

Changes in the frontal plane angulation of the calcaneus with foot orthoses are not related to outcomes:

 

Rearfoot posts and forefoot posts may be designed to not only alter the frontal plane angulation of the orthosis to the ground, but also to alter the sagittal plane angulation of the device relative to the ground. I commonly use heel lifts and anterior edge thickness modifications in my orthosis prescriptions to alter the sagittal plane of the orthosis in the shoe to obtain the therapeutic orthosis goals for the patient. The heel height differential of the shoe will also greatly affect sagittal plane angulation of the orthosis relative to the ground. Of course, since the orthosis lies basically parallel to the transverse plane in the shoe and is limited in its transverse plane position by the internal morphology of the shoe, then posting can not significantly affect transverse plane angulation of the orthosis relative to the ground.

The triplane wedge was supposedly developed by Dr. Mert Root at CCPM as a simply modification that could "control calcaneal eversion". Dr. Ron Valmassy taught this to us as students as a quick in-shoe modification for pediatric flatfoot deformity, especially in the early walker to 3 year olds. Instead of the triplane wedge, I prefer using a medial cobra pad modification with adhesive felt to accomplish a similar purpose for these patients.

 

Agree that most focus on frontal plane angulation... probably because it is easiest to visualise.
It could be argued that an inverted type of orthosis is an example of this thinking, however it is my personal belief that one of the positives of the Blake inverted device is that as the inversion increases, the inclination of the cast also increases. This is then more of a tri-planar force though most would think only of the inversion component...

 

The frontal plane dominance could be said to be an artifact of the dominance of Root Theory in teaching institutions for 25+ years perhaps. Most folks have been/are taught to watch for the demon bogey pronation from in front or behind.....it's fairly recently that other paradigms are being talked about as legitimate ideas rather than a violation of the Holy Scripture. Other stuff is getting into print now and when the Root style devices are the only ones taught to be made...and as making them drops out completely from the undergrad training there is even less chance of getting people up to speed with the more intimate details of very specific observations of motion patterns and tailoring an orthosis to suit this.

regards Phill Carter