2/3/2014 3:28 PM
A fairly common complication for patients with cavus foot type who begin wearing orthosis is to develop pain on the dorsum of the foot secondary to shoe pressure.
Without orthotic devices, the foot is allowed to collapse somewhat which will decrease pressure on the dorsum of the foot. This collapse does, of course, often lead to the symptoms that brought the patient into your practice in the first place. These symptoms are, of course, often treated with foot orthoses. But by placing an orthosis under the arch of the foot, particularly one that conforms well to the arch, it can have the effect of increasing pressure on the dorsum of the foot.
There are several options to address this issue.
The first and most important is to advise all patients with cavus feet of this possibility prior to casting them for orthotic devices. They should be advised that they are going to need to get new shoes to fit with the orthosis. In most cases, the patient can easily find shoes that will fit their foot and the orthosis and not result in excessive pressure on the top of the foot.
In cases where the foot is very high and there is a much greater than average midfoot volume, these patients may require extra-depth shoes. I often recommend the brand Aetrex as they offer extra depth throughout the shoe, but for the most part have shoe models that look like normal walking and running shoes without that “orthopedic shoe” appearance.
The second treatment option is to modify the lacing pattern of the shoe so that you avoid having laces going across the foot at the painful area. At left is a sample of such a lacing pattern.
The third option is to adjust the orthosis is a way to decrease pressure from the shoe on the top of the foot. The most effective way to do this is to first grind the heel of the orthosis as thin as possible so that it sits low in the shoe. With polypropylene orthosis, you can grind this to be essentially paper thin. In addition, you can thin the arch of the orthosis in the mid arch. Use a grinder to grind thinner from the bottom of the orthosis. By slightly thinning the orthosis, you will increase the flexibility of the device letting both the foot and the orthosis collapse a bit thus decreasing pressure on the dorsum of the foot.
Finally, I advised these patients that some of the softer athletic shoes that have been popular recently, such as the Nike Free, tend to be quite shallow and often do not accommodate high arched feet very well, particularly when an orthosis is added.