When An Orthosis Causes A Patient To Feel Laterally Unstable

Larry Huppin DPM

A colleague had a patient who presented with plantar fasciitis symptoms and he made her a pair of posted orthoses with a minimum cast fill. The devices worked extremely well at relieving her symptoms. The only problem is now she is feeling like she is somewhat laterally unstable on the left side only. She told the podiatrist she “wishes she had something to push her inward a little bit.”

This is a fairly common problem with patients who receive an orthosis that conforms extremely close to the arch of the foot. This type of orthosis tends to work the best at relieving tension on the plantar fascia and corresponding plantar fasciitis symptoms. However, because the orthosis conforms so closely to the arch of the foot, there is a potential that the patient can feel it to be somewhat over aggressive in pushing him or her laterally.

There are a couple of easy ways to address this problem. The first one is to add a valgus extension to the orthosis in order to apply a pronatory force to the lateral forefoot. The second method to address the situation is to make the orthosis more flexible so it does not apply as much of supinatory torque to the foot.

Given that this patient requested “something to push her the other direction,” a logical starting point would be to add a valgus extension. However, rather than add the permanent valgus extension immediately, I recommended that my colleague start by simply adding a temporary valgus extension using self-adhesive felt. He can fabricate a valgus extension from 3 mm felt and apply that to the orthosis just distal to the anterior edge of the device. He can then give the patient a couple of more pieces of felt so after a week or so, she can add another layer. A week after that, she can add another layer and find out how much she really needs to feel the most comfortable and supported. Once my colleague determines what works best for the patient, he can add a permanent valgus extension.

Another option would have been to simply take the orthosis to a grinder and, from the bottom of the device, grind the arch somewhat thinner to increase the flex. This would decrease the supinatory force being applied to the foot. This is what I do in my office most of the time and, in fact, is the most common modification we do to orthoses in our clinic.

Editor’s note: This blog was originally published at
http://www.prolaborthotics.com/Blog/tabid/90/EntryID/476/Default.aspx and has been adapted with permission from Lawrence Huppin, DPM, and ProLab Orthotics. For more information, visit www.prolaborthotics.com .

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