A Closer Look At The Principles Of Fluid Dynamics As They Relate To Orthoses

Dennis Kiper, DPM

   The term “overpronation” is controversial. For others, descriptions such as excessive pronation or excessive pronation movement, abnormal pronation or hyperpronation may be more suitable. Working with the silicone dynamic orthotic has made me confident that overpronation (in whatever form) represents the entire range of motion of the midtarsal joint in any gait cycle, which results in maximum or partial instability during locomotion of the kinetic chain.

What The Research Shows About Traditional Custom Orthoses

Traditional orthotics have been based on concepts of foot control by Root, Weed and others. The level of efficacy in clinical studies comparing over-the-counter and prefabricated products with custom functional orthotics have demonstrated results that are questionable in my opinion, considering this medical technology is about 60 years old.

   The Landorf study is well known for its conclusion that there is little difference as far as beneficial effects between custom and prefab orthotics, not only in the short-term but in the long run as well.8

   A 1999 study involving 236 patients concluded that, “when used in conjunction with a stretching program, a prefabricated shoe insert is more likely to produce improvement in symptoms as part of the initial treatment of proximal plantar fasciitis than a custom polypropylene orthotic device.”9

   One of the greatest problems custom orthotics have faced in terms of clinical efficiency and long-term effects is that there is zero published research indicating that orthotics have any long-term preventative value in terms of “wear and tear” or other musculoskeletal problems. There are two reasons for this. First, there is no follow-up to adjust the prescription orthosis as the foot undergoes physiologic and biomechanical changes of its "optimal" position on the ground after one or two years. (Patients can experience several prescription changes up to 10 years.) Second, there is too much inconsistency in duplication of pronation control in both new and existing patients with traditional manual technology.

In Conclusion

Reducing and minimizing the newer increased pronation movement can occur by using the silicone dynamic orthotic with as little as 2 mg of fluid to make a difference in articular apposition and symptoms. Due to the measurement of fluid weight in grams, one can consistently repeat or change a prescription precisely. The blend of fluid mechanics and biomechanics will always work the same if administered with a custom prescription.

   The siliconedynamic orthotic has been in clinical use for over 20 years for the treatment of most lower extremity biomechanical inflammatory conditions and pathological ulcers of the feet with the exception of neuropathic disorders such as spastic flatfoot.

   The ability of the silicone dynamic orthotic to enhance quantitative biomechanical foot alignment and dynamic stability for walking and running can add greatly to the arsenal of orthotic technologies available today.

   Dr. Kiper has specialized in sports biomechanics for over 30 years and is one of the nation’s top practitioners utilizing fluid technology in orthoses. He has published over a dozen articles on biomechanics for magazines, periodicals and online. Dr. Kiper has disclosed that he markets the silicone dynamic orthotic.


1. Quesada PM, Sawyer FD, Simon SR. Temporal and gel volume and effects on plantar pressure relief with use of silicone gel-filled insoles. Presented at the 21st Annual Meeting of the American Society of Biomechanics. Clemson University, South Carolina, September 24-27, 1997.

2. Root ML, Orien WP, Weed JH. Normal and abnormal function of the foot. Clinical Biomechanics, 1977.

3. Lundgren P, Nester C, Liu A, Arndt A, Jones R, Stacoff A, Wolf P, Lundberg A.
Invasive in vivo measurement of rear-, mid- and forefoot motion during walking. Gait Posture. 2008; 28(1):93-100.

4. Blackwood CB, Yuen TJ, Sangeorzan BJ. The midtarsal joint locking mechanism. Foot Ankle Int. 2005; 26(12):1074-80.

5. McPoil TG, Cornwall MW. The effect of foot orthoses on transverse tibial rotation during walking. J Am Podiatr Med Assoc. 2000; 90(1):2-11.

6. Baxter D. The ideal running orthosis. Biomechanics. 1996; 3(3):42.


Although I thought this article was generally weak and had "cherry-picked" the literature along the way, I do believe that fluid dynamic technology could be successfully incorporated into foot orthoses. I don't believe the present iteration which Dr. Kiper markets is necessarily the best way to incorporate that technology, but I should be happy to work with this technology in the development of more advanced foot orthoses.

Dr. Spooner,

I am curious about a couple of things you said. First, you stated that the article was “weak"? What do you mean by weak? Can you be more specific? Then you stated that I had “cherry-picked” the literature. Doesn't one normally try to support the statements and concepts made by using the research of others? I think I did that. I articulated the mechanics of motion and biomechanics, and I've indicated several points of principles of physics applied to these orthoses.

There isn't any science basis for traditional orthoses that I'm aware of. Perhaps that has changed. Can you enlighten me on this?

Why don't you address these things? Why don't you pick apart what I've said specifically and offer us a more constructive criticism rather than be so vague?

Lastly, you mentioned that you'd be glad to work with the technology in the development of more advanced orthoses. Perhaps you're not familiar with the Pedobarograph, but for an experienced clinician in biomechanics, I think it is simple to read. After all, when I first saw this technology and ran tests with Dr. Krinsky, we recognized right away that it shows a very improved gait efficiency with the orthoses versus without the orthoses. How much more advanced would you make this orthotic based on that?

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