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Foot Orthoses (“Orthotics”) and Specific Muscle Activation and Rehabilitation
Written by Dr. SkibaWhen people complain of almost any chronic lower leg injury, the reflex response of fellow athletes is usually, “Do you have orthotics?” For better or worse, these little shoe inserts are thought to have amazing powers of healing for athletic injuries. In recent years, investigators have been looking at the subject more closely. Thordarson’s group in Los Angeles has taken to using MRI, and asking the question, “Can we see any difference in muscle use with or without orthoses?” In other words, do these things actually change how your legs work, or are we all just kidding ourselves?
First, we should develop a little background. Orthoses (the medical term for orthotics) do not work on the sole basis of providing support for bony foot structures, although they do in fact do that. They also work by positioning the foot such that the various muscles are able to pull at just the angles they are supposed to. In this way, the correct muscles bear the proper load, reducing injury and allowing those muscles to become stronger and develop as they should.
In this study, the investigators selected several uninjured people with pes planus (that’s ‘flat feet’ to you and me), and used MRI to examine the activation of the tibialis posterior, which runs up the back of the leg. They wondered how the muscle would be activated in people with flat feet, and if this could be changed by putting over-the-counter inserts in the subject’s shoes. So, the subjects were made to perform exercises known to activate the tibialis posterior both barefoot and with the shoes/inserts, and they took pictures in both cases.
Perhaps not surprisingly, the data showed that flat-footed people activated many muscles in addition to the tibialis posterior. However, the investigators were able to show a much more selective activation of tibialis posterior with the shoes and inserts. Thus, it would seem that the orthoses work as advertised. You really can get the body to do what you want it to by using orthoses. Or can you?
Don’t get me wrong; I like inserts. I use them. I have put a lot of patients on them. However, this study does not examine the orthoses alone. It examines the orthoses in the shoes. In other words, we cannot know if these results are due to the shoes, the orthoses, or the combination of both. A better way to do the experiment would have been to also take pictures with the subjects wearing shoes without inserts.
All that being said, the study was reasonable. A future study could involve replicating this work in persons diagnosed with tibialis posterior injury, in order to find if the inserts have any bearing on the speed of rehabilitation. This work does give us reason to strengthen our belief the proposed mechanism of action of foot orthoses, and at least should make us feel more secure in trying them in the face of injury.
References:
Kulig at al. Effect of foot orthoses on tibialis posterior activation in persons with pes planus. Med. Sci. Sports Exerc. 37(1): 24-29. 2005.
