Conway McLean, DPM, Journal columnist

How well do you walk? I’m not expecting an answer of course. The question is not only hypothetical, it is also nearly impossible for anyone to say. We rarely get the opportunity to objectively observe our own personal gait type. And how many of us critically assess the intricacies of how well passing strangers are able to walk? But our musculoskeletal system functions to keep us upright and moving from point A to point B via the act of ambulation, a task critical to our health and well-being.

We are all different in myriad ways, some big and some small. These variations extend to the musculoskeletal system. A difference in alignment or anatomy will generally result in changes to foot and leg mechanics, their positioning, as well as their motion. Research continues into this important and exciting topic: the mechanical functioning of the human body. How and why do problems develop, especially pain, when things don’t move as they should?

For example, perhaps your foot flattens more than normal when you stand and walk, a motion termed pronation. In the appropriate amount, this is a healthy component of gait mechanics, allowing the foot and leg to absorb the impact generated by each step taken. But too much of any specific motion will lead to problems. This excessive rolling down of the arch is a common finding, not a rarity. This can exert abnormal tension on the ligaments, tendons, and other soft tissue structures on the bottom of the arch. Eventually, pain will develop as one or more of these becomes inflamed and diseased. More often, this is a gradual process, although the signal that there is a problem, pain, may seem to appear suddenly, despite the enduring presence of the biomechanical issue leading to inflammation.

If there were only some way to prevent the abnormal motion that occurs when a poorly aligned foot comes in contact with the ground. Gravity is generally going to win any battle against bad bone architecture. At least, without the correct amount and type of support. Bringing the ground up to the foot would prevent some of that excessive motion occurring in a foot varying from the norm, from proper alignment. This is one of many functions of a properly prescribed pair of foot orthotics.

These are customized medical devices inserted into the shoe to correct abnormal or irregular foot, leg, and body mechanics. Most people would look at one and simply call it an arch support. And arch supports of various types are popular and big business. The global foot orthotic insoles market, including both pre-fabricated and custom devices, was 3.25 billion dollars in 2019. It is expected to only grow larger as the population ages and more people take up the practice of physical fitness.

Foot orthotics are prescribed for a host of pains and problems, some which might not seem obvious. One particularly common reason for recommending better foot support is pain in the ball of the foot. Another is heel and arch pain. Because of the complex connections between all parts of the human body, foot positioning also has a profound effect on leg and spine function.

This is partially due to the location of the foot half of the ankle joint, a bone wedged between the two lower leg bones. When the arch collapses, this foot bone turns more to the inside, which in turn causes the lower leg to rotate inward excessively. Alignment of the spine can easily be affected.

Many have found relief from chronic back pain by using prescription supports, especially effective when fabricated via a rigorous process of examination and observation. The creation of a perfect copy (hopefully) of the foot makes the end result not only more comfortable but more therapeutic. Some methods for producing this replica of the foot are more precise, more reliable, than others. Some are just bad. The top experts in biomechanics recommend the use of plaster for making this copy, mostly due to its precision and reliability, despite it being slower and messier. When applied properly, even the faintest of skin lines are seen in the cast.

The position of the foot and leg, when the copy is made, is of tremendous importance. Those made while standing are often just capturing the deformity, resulting in a device providing no benefits. But if the replica of the foot is created when the arch is relaxed, the device won’t be comfortable, the arch too prominent. After all, the position of the foot is very different when bearing weight versus hanging in the air, relaxed.

This part of what should be a complex process is best performed when the patient’s feet are hanging down, as if someone were kneeling on a seat. With some of the other methods, the best position for proper biomechanical function is difficult to find. Although, too often, this ideal position is ignored completely. When the foot is hanging, it can easily be placed into exactly the right position for optimal gait and stance.

One of the keys to success in the prescribing process for foot orthotics is analyzing the individual’s gait type. Videography of someone walking on a treadmill, viewed in extreme slow motion, can impart valuable information. Evaluating x-rays taken while the subject is standing, as opposed to lying on the x-ray table, should also be part of the prescribing process. All sorts of evidence is pertinent when planning the intricacies and specifics of an orthotic prescription.

Many important variations are often part of the script for a typical device, all depending on the individual’s foot type, lower extremity function, gait style, activities, weight, shoe type, etc. A full accounting of each and every possible component is not possible in a document of this sort, but some of the typical parts of this prescription include the amount of slant of the surface supporting the heel (relative to both the ground and the leg), the degree of slant to support the forefoot (aka the ball of the foot), the height of support to the arch, and so many more. Because the big toe and the 1st metatarsal move in a manner unique to the human body, special accommodations should be made, depending on the individuals specific attributes.

Therein lies the magic and science of prescription foot orthotics. A knowledgeable specialist will utilize all manner of data and information to reach a conclusion on the proper components, materials, size and shape, to correct someone’s patho-mechanics, the abnormal lower limb function leading to pain. Too often, none of these steps are taken, which is why the success rate of custom foot orthotics is poor. The conclusion: they are improperly prescribed far too often, with no accounting of the patient’s variances from the norm.

Many have pain resulting from a biomechanical issue. Would some kind of supportive device placed inside your shoe help? But would just any support do the job? Do you need a prescription support instead of a pre-made one? Many different health care providers dispense foot supports. How familiar are they all with foot and leg mechanics? How practiced at the nuances of gait analysis? Better biomechanical function can aid in the health and welfare of many aspects of health, from improved cardiovascular function to psycho-social benefits. It happens: peace of mind through better biomechanics. All the result of a little piece of plastic in your shoe.