How Foot Orthotics Work

There are many misconceptions as to what orthotics are or how they work. Contrary to popular belief, not all orthotics are the same. Depending on a variety of factors from the assessment, method of capturing the shape of the foot, to the materials used, there are literally dozens of types of orthotics that can be made.

 

Some fly by night operations simply claim that are orthotics are an arch support to keep the foot and lower limb vertical and prevent the turning in or (pronation) of the foot. However, the true purpose of their effectiveness goes much deeper than that.

Many foot and lower limb conditions and aliments are a result of improper biomechanics (movement). Simply put, when the foot veers away from its normal function it can lead to a chain reaction of events that can cause pain and discomfort. An important thing to remember is the concept of force and how its applied to the foot.

 

The goal of orthotic therapy is to target the underlining cause of the problem, which is often the improper biomechanics of the foot. When we perform our computerized video gait analysis, the main thing we look at is the amount of motion in the foot (in particular the sub-talar joint which controls the amount of pronation and supination in the foot). We are able to quantify that compare with it what is normal, abnormal and severe based on data from over 50 years of patient examinations. We want to have an idea as to what the feet doing while in motion and not just when you are standing still.

Normal Gait Pattern
Normal Gait Pattern

As human beings we are designed to walk in a particular pattern known as the “gait cycle” so that force applied to the feet follows the precise pattern in order efficient locomotion as illustrated on the right. The foot has to make contact with the ground on the outside (lateral) aspect of the heel. From there the force has move along the outside of the foot until it reaches the mid foot where the joint called the (calcaneo-cuboid joint) acts to transform the foot from a mobile adaptor to a rigid lever (strong enough to propel the foot forward). From that point the foot must pronate (roll inward) approximately 4-6 degrees in order to make contact with the ground with the big toe and  propel all the weight forward off of that joint.

Excessively Pronated Gait Pattern
Excessively Pronated Gait Pattern

When the foot deviates from that pattern, often times in a pronated pattern, the foot will instead hit the ground on the middle to inside part of the foot and the force continues on the medial (inside) part of the foot (where it is not designed to go) then move towards the space between the 2nd and 3rd toes then push off on the inside part of the big toe (often resulting in callusing on the medial side of the toe).

 

In essence, when the force deviates from the normal pattern, it can cause a number of problems in the foot and lower limb as a result of force being placed on certain areas of the foot that are not designed to handle. So the orthotic is designed to be made specifically for your foot so that we can alter the ground reaction forces applied to the foot and alter the pattern of gait so that the foot returns to normal function during movement.