How Do We Define A Custom Foot Orthotic?

I attended the Federation of International Podiatrists (FIP) meeting in Miami, Florida last month and was honored to participate on a panel that discussed the best definition of a custom foot orthotic.

Keep in mind that this is a group of podiatrists from all over the world. While FIP members are primarily based in Europe, North America and Asia, the organization also has emerging podiatric professionals from other countries.

One of the first things I learned from talking to audience participants was that not all the podiatrists there had the ability to diagnose and/or write a prescription for an orthotic to be dispensed. It appears that they all could examine patients, perform casting and then decide on the best prescription elements to build into the foot orthotic though.

Now, going into this discussion, I thought the most important point to keep in mind when deciding how specifically to define custom foot orthotics is to understand what types of devices are currently available all over the world and are known in some capacity to laypeople.

I listed these available foot orthotic devices in three basic categories: 

• over-the-counter (OTC) foot orthotics; 

• custom-molded foot orthotics; and 

• prescriptive foot orthotics with patient-specific prescriptive elements built into them.

I consider specific prescriptive foot orthotic elements to be things such as forefoot and/or rearfoot posts, heel lifts (bilateral or unilateral), first ray cutouts, Morton’s or reverse Morton’s extensions, etc. 

From my perspective, and as I explained to the audience at this panel discussion, the building of prescriptive elements into a foot orthotic is the most important aspect for defining an actual custom foot orthotic. I do not think that just taking a custom mold of a foot is good enough to make a device prescriptive, no matter what technique you choose to use for that “foot cast.” I also feel that you can modify an OTC device with add-on patient-specific prescriptive elements and make it work almost as well, or as well as many or most custom-molded prescriptive devices. That does not make it “custom” to that patient’s foot though.

Ultimately what it comes down to is the fundamental question: does the device work for the patient or not? If an OTC device is adequate for most of the world’s population, so be it. However, we know that OTC devices are not always enough. As podiatrists, we tend to put great weight into whether a foot orthotic was custom-molded but is that enough?

In most studies that compare OTC devices and custom-molded devices with no prescriptive elements, researchers often see minimal kinematic or kinetic differences in the function of those devices. What they do tend to find is that the custom-molded foot orthotics are usually deemed more comfortable than the OTC devices by the study participants.^1-4

In the few studies that have looked at the difference between OTC or custom-molded devices versus a patient-specific modified OTC or custom-molded device, that is where the kinematic and kinetic differences emerge.^5,6 

Ultimately what matters is whether the devices are made with specific prescriptive elements for the individual patient, whether the devices are comfortable and whether they will actually be worn by the patient with foot and/or ankle pain. 

Overall, I believe that “custom foot orthotics” should be produced from a custom mold of the patient’s foot via any accepted casting or scanning technique and the devices should have specific prescriptive elements added to the device that are tailored to that patient’s pain and dynamic and/or physical assessment.

Happy holidays everyone and thanks for reading!

Dr. Williams is a Past President and Fellow of the American Academy of Podiatric Sports Medicine. He is the Director of Breakthrough Sports Performance, LLC in Chicago. Dr. Williams has disclosed that is the Medical Director for Go 4-D and a consultant for HP FitStation.

References

1. Martinez-Santos A, Preece S, Nester CJ. Evaluation of orthotic insoles for people with diabetes who are at-risk of first ulceration. J Foot Ankle Res. 2019;12:35. 
2. Yick KI, Lo WT, Ng SP, et al. Analysis of insole geometry and deformity by using a three-dimensional image processing technique: A preliminary study. J Am Podiatr Med Assoc. 2019;109(2):98-107.
3. Bus SA, Ulbrecht JS, Cavanagh PR. Pressure relief and load redistribution by custom-made insoles in diabetic patients with neuropathy and foot deformity. Clin Biomech. 2004;19(6):629-638.
4. Owings TM, Woerner JL, Frampton JD, Cavanagh PR, Botek G. Custom therapeutic insoles based on both foot shape and plantar pressure measurement provide enhanced pressure relief. Diabetes Care. 2008;31(5):839-844.
5. Wrobel JS, Fleischer AE, Crews RT, Jarrett B, Najafi B. A randomized controlled trial of custom foot orthoses for the treatment of plantar heel pain. J Am Podiatr Med Assoc. 2015;105(4):281-294.
6. Braga UM, Medonca LD, Mascarenhas RO, et al. Effects of medially wedged insoles on the biomechanics of the lower limbs of runners with excessive foot pronation and foot varus alignment. Gait Posture. 2019;74:242-249.