Back in my podiatry student days, we learned that the purposes of custom foot orthoses were to “make the foot function in the subtalar joint (STJ) neutral position” and “prevent compensation for foot deformities.” We also learned that the overpronated foot led to an increased risk of injuries and supinating the STJ toward its neutral position from an overpronated position with a foot orthosis was good. It would have been sacrilege as a podiatry student to suggest that podiatrists should sometimes make foot orthoses pronate the foot to improve the patient’s symptoms and gait function.
Thankfully, a lot has changed in podiatric biomechanics from my time as a podiatry student over 35 years ago. One of the most important ideas to come along is tissue stress theory, which teaches that custom foot orthoses should be specifically designed to relieve the pathological stresses on the injured tissues of the foot and lower extremity, and to optimize the function of gait versus trying to make the foot function in STJ neutral position. One of the key considerations that I have taught over the past decade in my lectures on tissue stress theory is that in order to reduce the stress on an injured tissue, you must design foot orthoses in an attempt to duplicate the function of that injured tissue.
For example, in the case of treating posterior tibial tendinitis, one should design the foot orthosis to supinate the STJ since the function of the posterior tibial muscle is to supinate the foot. Tissue stress theory also teaches that in the case of treating peroneal muscle strain, peroneal tendinitis or peroneal tendinopathy, the clinician should design the foot orthosis to pronate the STJ since the function of the peroneal muscles is to pronate the STJ.
Yes, you heard me right. Sometimes, it is beneficial to pronate the foot with an orthosis.
It was over 30 years ago, during my first few years of practice, when I first discovered that pronating a foot with an orthosis may have quite positive therapeutic effects. At that time, a 55-year-old male house painter presented to me with chronic peroneal tendon pain, which was so severe he was considering quitting the job he loved. He had high-arched feet with tenderness and edema directly over the peroneal tendons of his left ankle. The patient had already seen three other podiatrists who had each made him a pair of custom foot orthoses that had all failed miserably at relieving the man’s ankle pain. He told me that I was his last hope to allow him to continue working.
When I examined his foot and ankle, I could clearly see that his peroneal muscle and tendons were tonically active during standing in order to keep his high-arched foot from being oversupinated. I told him that I thought my foot orthoses would help him. He looked at me in disbelief and said, “Why do you think your orthotics will help me when the other orthotics did not help me?” I told him that my orthoses would be designed to push his foot away from his higher-arched position, which would, in turn, take the strain off his injured peroneal tendons. He didn’t look very hopeful with my explanation.
However, when I made a temporary valgus in-shoe wedge for the patient to simulate what my planned valgus-wedged orthoses would feel like, his hope returned. I adhered a 6 mm thick, valgus-skived piece of adhesive felt from the rearfoot to the forefoot of his shoe insole to pronate his foot. He immediately felt 50 percent relief of his peroneal tendon pain with walking on this valgus-wedged insole. My subsequent custom foot orthoses with valgus rearfoot, midfoot and forefoot corrections to pronate his foot allowed him to become completely asymptomatic within five weeks. He was very happy to be pain-free again so he could continue working in the job he loved.
Even though many podiatrists may be skeptical that anything good could ever come from purposely pronating a foot with a foot orthosis, this orthosis technique has consistently worked well for me over the past three decades in select patients. Once the large variation in foot structure within the human population and the biomechanical consequences of this variation in structure are more completely understood, open-minded podiatrists will realize that making their patients pronate more with their orthoses can, sometimes, be a very good thing.
Dr. Kirby is an Adjunct Associate Professor within the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University in Oakland, Calif. He is in private practice in Sacramento, Calif.