For Doctors – Medical Orthotic Insoles

Evidence-Based Medicine Applied to Dynamic Foot Orthotics

By Allan Grossman, DPM, FACFAS, FAPWCA – ©2013

Biomechanical corrections applied to the foot orthotic do not provide favorable results when tested in a computerized foot gait lab. New technology has given us the ability to analyze with great detail the positions of the foot when both static and dynamic forces are applied to the foot. To obtain consistent effective outcomes from any orthotic products, we must take a new approach in basic orthotic design. Through 10 years of research and 10,000 successful patient outcomes we have conclusive evidence that will improve your foot orthotic results.

Harrisburg Foot & Ankle is unique in podiatry and orthotic solutions. They work with a full physical therapy department that coincides with their podiatry practice. To obtain objective data in the use of an orthotic on the foot, the patient completes a comprehensive foot gait analysis which includes video analysis, in-shoe sensors and computer analysis. A patient is often prescribed physical therapy to correct dysfunctional patterns in their gait and increase the stability of their ankles, foot, knees and hips. Therapists work to correct alignment, re-train gait and help a patient walk and/or run more efficiently. This combination of therapy and foot gait analysis provides an abundance of objective data that can be used in two ways: first, it validates the medical necessity of an orthotic to insurance companies. Second, it confirms the effectiveness of a patient’s orthotic in leading to the highest patient recovery.

One of the most effective tools in a gait lab is the in-shoe foot pressure mapping sensor system. This is placed between the foot and the orthotic to gather data for computer analysis. There are several orthotic pressure mapping scanners on the market, Harrisburg Foot & Ankle uses the F-Scan system. This is an effective tool that delivers a wealth of data related to foot dynamics and foot gait. It is vital to have a correct interpretation of that data about the foot which allows us to use the information to the advantage of the patient.

In the Harrisburg gait lab, both prefabricated and custom manufactured orthotics from many labs have been extensively tested. Traditional biomechanical corrections built into an orthotic are not effective once the foot starts to move in a functional capacity.

It is important to understand what the orthotic should accomplish during the gait cycle. Orthotic therapy should be to help the patient with a central heel strike, neutral positioning during mid stance, and then moving to a solid toe off during the propulsion phase of gait.

Typically, a patient will strike their heel with an inverted foot/ankle, which increases the pressures on the lateral aspect at mid stance. This also makes it more difficult to complete toe-off through the 1st MTPJ and Hallux.

Neither scan shows a powerful toe off in the propulsion phase of gait. This lack of pressure in the toe-off phase correlates with other problematic compensatory patterns. For example, a patient may externally rotate the feet or hips in order to keep moving forward. This external rotation can be the source of foot pain, knee, hip and back pain.

Foot testing shows very few if any custom or prefabricated orthotics producing a powerful toe-off. Custom devices attempt to control the arch with a rear foot post and through a specific arch height. Controlling the arch does not allow for an effective drop of the first ray. Labs offer a cut out for the first ray, however through gait analysis studies with an actual patient, it has shown repeatedly that first ray cut outs of various shapes and sizes fail to increase any significant pressure at the toe joint. Additionally, deep heel cups of all sizes recurrently hinder the first ray dropping. Remember, the most effective orthotic must allow a central heel strike, neutral arch at midstance and a powerful toe off with no need for external rotation from the foot, knees or hip.

To accomplish a uniform pressure and more effective gait we need to control the foot with several components.

The arch needs to be controlled so the foot does not pronate or slide off the device. Notice that the arch incorporates a medial flange rather than just a high arch which tends to push the foot laterally. Valgus posting drives the foot into pronation which is controlled by the medial flange which prohibits over pronating. The final part of the orthotic design is to drop the first ray in the medial forefoot. Rather than a cut out, it has been found that tapering the medial forefoot promotes a solid first ray drop. This design allows the foot when in motion to hit centrally, maintain a neutral mid stance and finish with a powerful toe-off. The need to over compensate elsewhere is eliminated. This combination helps reduce most of the causes of functional foot pain. Current technology gives us more than anecdotal or observational information allowing us to objectively support decisions in orthotic fabrication for our patients. This same technology has also allowed us to develop a more effective product leading to better outcomes, increased satisfaction and higher margins of success.

A patient with excessive pronation in the foot often show increased wear on the lateral aspect of their shoes. The wear is caused by pronation and jamming of the big toe joint. By adding a varus heel correction to an orthotic, this will not increase the ability to push off the toe joint because the patient will stay on the lateral aspect of the foot.
However, by adding a valgus heel post, the heel strike centralizes, while the medial arch support or flange blocks over pronation and a valgus forefoot and tapered first ray insures a proper toe off.

Traditional orthotics only correct the foot in a static position. Heel cups appear like they control eversion and medial rear foot posting appears to control pronation which makes the foot look like it will function correctly. When the foot is in motion all the standard corrections fail to produce effective foot pressures. With computer pressure sensors we can now monitor what is happening in real time with the foot in motion. This information creates a new dimension in functional orthotic control.
Be open to advancing with technology and your practice will improve. Dr. Allan Grossman is the director of Harrisburg Foot & Ankle. He performed his surgical residency at Cambridge Hospital/Harvard Medical School and is Board Certified in Surgery. He also completed an AO orthopedic Trauma Fellowship and has served as a Medical Advisor for PFA. In addition to his clinical practice, Dr. Grossman is the Associate Residency Director for Pinnacle Health Systems Podiatric Surgical Residency and Co-Medical Director for The Holy Spirit Wound Care /Center For Wound Healing. He is also the Medical Director for Select Medical/ First Choice Rehab Center Gait Lab.