The Problem with Orthotic Studies
Orthotic studies I've read in my professional journals or elsewhere are "faulty", because in every study ever published, whether they use a custom, pre-fab or OTC type, the researchers only records what happens with that set.
Posted Thursday, 28 December, 2006
So if it helps for a while, and then the beneficial effects start to change and diminish, the study does not make any adjustments or a new prescription to take into account the biomechanical and physiological changes that take place resulting in a new more efficient alignment position.
When an orthotic is successful in getting someone on the road to recovery, there is a change in the "allowable range of motion" of pronation which increases due to a reduction in inflammation and tension of the soft tissues (which is why you have pain). This results in increased flexibility secondary to an improvement in the health of the tissues, thus an increase in the allowable "range of motion" of pronation.
The key to a long term benefit of any orthotic is to "minimize" (not arrest) overpronation. As health of the foot improves, overpronation starts to become greater in its "allowable range of motion" AGAIN (consider the fact that most parts or systems of the body changes throughout our life, e.g. eyes, kidneys, skin etc, etc)
Not making or adjusting for these changes in pronation, leads to a short term effect, which can be anywhere from a few months to a couple of years in most cases.
The difficulty in most custom orthotics today is recapturing the new optimal alignment position (AKA-neutral position) to account for those changes, and with pre-fab or OTC, buying a new orthotic is just buying the same product with the same position the manufacturer has designated. And since most of them are designed to "under correct" rather than "over correct", well, good luck.
The changes that take place in healing are a matter of probably a couple degrees or so in the optimal alignment postion (I have never measured it, but it would probably be a great research project for a resident in training to do) and it is this small change that makes the functional alignment continually more efficient in order to maintain and continue to improve microscopic healing that takes years to restore.
So as the efficiency of any orthotic starts to wane, it is not unusual for symptoms to start to recur, which in my experience for the first change takes about 1-2 years in most cases.
Today there are new orthotics which don't fit into the paradigm of orthotic or functional control, based on rear foot control. In fact there was an article recently in "Biomechanics Magazine" that discussed "midfoot" control, which to me is the better way.
But here again, the issue for me becomes one of an orthotic that matches the way you walk (guiding the foot, not controlling it) and not just the shape of the foot and doesn't interfere with the normal footstep like rigid orthotics.