Functional stability is a tri-planar concept involving the coronal, sagittal and transverse planes. In most cases the deficits that we discover are most obvious in the coronal or sagittal planes. Subsequently, most of our orthoses are designed to provide control to deviations in these two planes as well.

 When you are evaluating different deviations and compensations, please take a moment to also consider the ramifications in the transverse plane. Children adapt very quickly, and are not concerned as much with how they get from point A to point B, as they are with just getting there consistently. Compensations, such as lateral trunk lean over the orthotic side in stance phase, can occur because of limitations to normal transverse plane motion. When this normal motion is taken away distally it will often manifest itself proximally with compensations. Now this deviation in particular can occur if the stance side abductors are weak, but it can also occur if the same hip abductors and external rotators do not have the opportunity to undergo normal stretch reflexes, which signal these muscles to “turn on” during the gait cycle. 

Transverse plane motion is every bit as important as coronal or sagittal plane motion to achieve functional stability. The effects can be significant whether they happen from the ground up or from the top down, and they happen regularly and repeatedly across the ankle, knee and hip joints during the normal human gait cycle.