Do Orthotics Work?

I don't wear orthotics, but if I did, I'd like to feel some confidence in their effectiveness, preferably backed up by plenty of research.

It seems, however, that there's some mystery about orthotics, at least that's the suggestion of an article in the January 17th NY Times summarizing the work of Benno M. Nigg. Dr. Nigg is a professor of biomechanics and co-director of the Human Performance Lab at the University of Calgary in Alberta, and he claims that the research is mostly inconclusive about whether orthotics work, and if they do, how they actually benefit athletes who use them.

To be sure, runners seem to like them. I'm pretty confident that among my readers there are runners who will swear that orthotics have helped them correct biomechanical issues and have allowed them to run injury-free. I'm willing to accept that evidence at face value: orthotics do help some people.

But here's one mystery: In Dr. Nigg's studies, he found there was no way to predict the effect of a given orthotic on an athlete. The article says:

"One person might respond by increasing the stress on the outside of the foot, another on the inside. Another might not respond at all, unconsciously correcting the orthotic’s correction."

Here's another mystery: assuming there is a biomechanical problem to correct, there seems to be little agreement about the best way to make an insert to achieve the desired effect. I.e., if the same runner visits a number of different certified makers of orthotics, he or she might come away with devices that take quite different approaches to correcting the perceived biomechanical flaw.

The article asks: what do orthotics actually do? Well, they don't seem to change the way the skeleton moves, but they do seem to make certain muscles work significantly harder (or less hard), and increase (or decrease) stress on certain joints. That sounds promising, but again, there seem to be few rigorous studies to show how to take advantage of these effects.

The article never mentions the issue of anatomical asymmetry -- having legs of different lengths or feet of different size. I found myself wondering whether studies might reach different conclusions with a more set of subjects who shared some such trait.

I suppose one hopeful conclusion came from one study of Canadian soldiers, in which half were allowed to choose from several different types of orthotics and the other half continued with none. The group that chose their own seemed to have about half the injuries of the control group. But here's yet another mystery: "...there was no obvious relation between the insert a soldier chose and his biomechanics without it."

Well, I suspect that the fault might lie with the sensitivity of the tests, but what do I know.

Hey wait, I haven't heard from Bob Chasen for a while. Unlike me, he is a professional and has thought about this stuff for thirty years. (If you have't read his blog, Taking Things in Stride, you should.) If you're out there Dr. Bob, would you care to comment? What does an orthpedist think about this unorthodox take on orthotics?