Wednesday, January 19, 2011

Do Foot orthotic Devices Work?



This post is in response to Jon Waldron , the author of the excellent Newton North blogsite. He asked me to comment on the January 17 article in the New York Times, so here are my thoughts.


In summary, the article doubts the effectiveness of foot orthotic devices (FODs) with the author backing up her points with quotes from the co-director of a human performance lab in Canada. FODs are usually discussed in terms of how they modify pronation and supination. These terms are one of the most simplified and abused terminologies in journalism today. With this article, add sensationalism to that list. It gets "eyeballs" to the Times website and sparks commentary but is not much good for more than that. This is because those eyeballs would glaze over if any attempt at what we really know about these foot motions were ever presented. These said motions describe tri-plane motions around a single joint and not a whole foot. For example pronation at the subtalar joints generally causes most of the foot to be a loose bag of bones while supination makes the bones to be a "rigid lever." However, at the neighboring mid-tarsal joints, pronation locks the foot rigid while supination causes the loose bag of bones" situation. That is the effect of only 2 of the 33 joints on basic foot motion. Dare we add in the others? How about force changes from the 100 or so muscles and tendons or the peak forces on the 26 foot bones. Don't forget the angular velocities transmitted from the rest of the body. We live in a world that is not black and white but somewhere along the spectrum of gray. The answer far less pessimistic than that of Gina Kolata article in the New York Times and far less optimistic than a foot orthotic device (FODs) chain that claims 98 percent sucess with its clients. IMHO, I see this as that classic academic/theoretical voice clashing with the clinical/practical stirred by the journalistic tempest in a teapot. For those of you that see a tipping point towards academia (Dr Benno Nigg) and away from the fee for service clinicians, think again. The article does not disclose that the good doctor has a financial interest with MBT shoes (Masai Barefoot Technology). These shoes are supposed to create instability and inefficiency in the short term to strengthen feet for the long term. Their thinking and selling point for their shoe line is that if you strengthen the muscles involved, you don't have to correct for any deformity. Hence, you can now better understand his obtuse comment that FODs are only a short term solution.


Of course foot orthotics devices work when given to someone who actually needs them and the results are long term. There is too much evidence based medicine to refute this. The kicker is that less than 10% of the injured runners that seek my care show clinical evidence that they would even benefit from FOD therapy. So we are talking about a small percentage of the general running population. Let me digress. Every runner that enters my office is screened for deviations at the subtalar and midtarsal joints as well as a host of other clinical and historical information. Dr Richard Schuster measured over 10,000 runners and found statistical correlations between these numbers and certain injuries. For example, he found a high correlation between abnormally high forefoot varus and patello-femoral syndrome. Then I take into account any structural and material "defects" in the foot or even specific things in the past medical history to honestly and profesionally decide whether a custom FOD is a viable treatment for this person or whether other avenues need to be persued. There are people "prescribed" FODs by unscupulous practioners and clinics that don't have much clinical evidence that they actually need them. People who get devices they do not need won't be helped and are sometimes hurt by such teatment. This is further fed by patients that think they need them, or maybe just want them. Then there is the group of people that show some evidence of needing correction but are given the wrong prescription. One area sports clinic had their FODs made by a 7 dollar per hour nurse's aide with no formal training. The outcome of wrong presciptions lead to truly random outcomes. one of the more common errors I see is how the foot impression is captured. Clouding the issue is that how a FOD fits into a shoe can affect how well or how badly the foot functions in that shoe.
For the record, I do think that some form of strengthening of specific foot stuctures within a reasonable margin of error can be injury reducing. However, I doubt that these new "toning shoes" are that answer. In that small percentage of people that have foot deformities that cause stress and forces that exceed safety limits of what that body part can handle, something must be done to reduce it. In those special cases, custom made proper prescription FODs perform quite well.

1 comment:

Walter Henson said...

I definitely agree with you that the piece you linked to was sensationalist at best. I don't know a lot about foot orthotics, but I've enjoyed learned from you and will definitely study it more, as I'm an aspiring runner who often gets sore feet!