MODELS OF FOOT FUNCTION: FAULTY DIAGNOSIS LEADS TO FAULTY INTERVENTION.

Tags: footfunction, Science

“The beginning of wisdom is the definition of terms” – Socrates

Many running injuries are attributed to ‘overpronation’ of the foot. The meaning of ‘overpronation’ differs almost as much as theories about how it arises. The model of foot function used determines how cause and solution are decided i.e. faulty diagnosis can lead to faulty intervention.

Various theoretical models of the foot have been created to simplify its complexity. A common model is the ‘tripod’ which is proposes weight bearing at the heel, first and fifth metatarsal heads, medial and lateral arches connecting heel and metatarsals, and a transverse arch across the metatarsal heads suspending the second to fourth from the ground even under load (Dickinson and Diveley, 1953). According to this concept, contact of the second to fourth metatarsal heads with the ground under load indicates failure of the supporting arches and a dysfunctional foot.

According to the scientific method, if theory and data disagree, the theory is wrong. Many studies have produced observations completely at odds with the tripod theory of foot function (e.g. Morton, 1935; Cavanagh et al., 1987), yet it is still used as a model of foot function in contemporary studies (Zeidan et al., 2019).

Though beautifully simple, the tripod model has led to faulty interventions including arch supports, so called short-foot exercises and stiff motion control shoes that exacerbate the problems they are designed to solve. This series of posts will introduce an equally simple but accurate model of foot function that explains dysfunctions leading to running injuries and how they can be fixed with functional footwear.


References:

  • Morton, D.J.(1935) The Human Foot: Its Evolution, Physiology, and Functional Disorders. New York: Hafner.
  • Dickson, F.D., and Diveley, R.L.(1953) Functional Disorders of the Foot, 3rd Ed. Philadelphia,: J.B. Lippincott.
  • Cavanagh, P.R., Rodgers, M.M and Liboshi, A. (1987). Pressure distribution under symptom-free feet during barefoot standing. Foot and Ankle International, 7, 262.
  • Hala, Z., Suzuki, Y., Kajiwara, Y., Nakai, K., Shimoura, K. Yoshimi,S.,
  • Tatsumi, M., Nishida, Y., Bito, T and Aoyama, T. (2019). Comparison of the changes in the structure of the transverse arch of the normal and hallux valgus feet under different loading positions. Applied System Innovation, 2, doi:10.3390/asi2010003.

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