I have been utilizing pressure mapping in my clinical practice for the last 17 or 18 years. In regard to foot function, what I can “see” with the use of a pressure mat or in-shoe pressure measurement never ceases to amaze me.
Pressure mapping started with the use of the Electrodynogram (EDG) system (Langer Biomechanics Group) about 30-plus years ago. The EDG system used small sensors that one would place on areas of the foot under the medial and lateral heel, first and fifth metatarsophalangeal joints (MPJs) and hallux. Newer systems now use full insole length and width devices that can show the pressures of the entire foot.
While we can debate the differences in the types of pressure mapping systems as to the ways they work and which ones work best, ultimately, it is a bit more important to understand what the pressure profiles are showing us about foot function.
There are several things we can quantify with pressure mapping. This includes the location of high pressures; the overall timing or duration of high pressures; and the center of pressure. The study of these factors can give you indications that the foot is functioning in a way that is not ideal and can be associated with specific types of foot symptoms and diagnoses. We can also use these measurements to assess whether a custom or customized orthotic or shoe has alleviated the poor functional indicators.
Also keep in mind as well that pressure itself is not the only useful reading you can glean from the use of pressure mapping devices. Timing is just as important, if not, at times, a more important data point. The ability to look at force versus time curves combines the two, giving you a unique perspective into how the foot and ankle work from heel contact to toe off.
I will discuss pressure mapping interpretations in my DPM Blog posts over the next year because “seeing” what is going on in the foot with and without an orthotic, or because of one shoe versus another, is really the best way to appreciate why pressure mapping is beneficial. Different shoes can cause the foot to function differently as can different prescription orthotic devices.