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Professional Preformed Orthotic Insoles

“3-Pod™ GRF Technology puts Spenco Medics™ Insoles miles ahead of every other professional preformed orthotic device.”

– Ray Anthony, FCPodS, DPodM, Podiatrist

The Research

Research indicates orthotic insoles produce only small, unpredictable, and subject-specific changes in foot posture and joint motion [1,2], and that the height of the medial longitudinal arch is a poor indicator of how the foot functions, i.e. how it reacts to vertical ground reaction forces (GRF) and is probably a pathomechanically insignificant metric. [3-7]

A number of recent studies suggest the symptom-relieving benefits of orthotic insoles may be primarily due to kinetic rather than kinematic changes in lower-limb function [8-10], i.e., orthotic insoles alter the magnitude, direction, and temporal patterns of GRF (external moments) on the plantar surface of the foot, which in turn alters the tensile and compressive forces acting upon the osseous and soft-tissue structures of the musculoskeletal system [8-10], and modulates the temporal activity of major muscle groups.


Ground Reaction Force (GRF)

GRF is a vector composed of vertical force, anterior-posterior shear, and medial and lateral shear. It has been postulated that only three orthotic design variables can alter the components of GRF:

  1. The top-surface geometry,
  2. The load-deformation or stiffness of the shell, and
  3. The frictional characteristics of the top surface of the device. [12]
Diagram

The Spenco Medics™ Paradigm

While all orthotic insoles with a heel cup and a degree of arch support will produce small and unpredictable kinematic changes in some wearers some of the time, they are likely to produce a greater kinetic effect in all wearers all of the time. When prescribing orthotic insoles as part of a comprehensive treatment program for lower-limb pathology, perhaps more than motion control, clinicians should consider how changing the magnitude and direction of GRF at the foot-orthosis interface may modulate the tensile and/or compressive forces acting upon the injured structure. For example, if an excessive pronation force is causing the tibialis posterior tendon to function outside its zone of optimal stress (ZOOS) as the etiology of tendinitis, and orthotic insole designed to increase the supination moments (reduce the pronation moments) should be dispensed without too much emphasis being placed on achieving a change in foot posture. This orthotic prescription method has been called the Tissue Stress Theory or Paradigm. [13]

Spenco Medics™ Preformed Professional Orthotics are available in four configurations: "Sport" with a blue, high-performance technical top cover and "Dress" with a leather-style brown top cover to complement most dress shoes. Both Sport and Dress are available in Full-Length and 3/4-Length for low-volume or tighter-fitting shoes. Spenco Medics™ Diabetic + Insoles come in Full-length only with non-replaceable heel and forefoot cushioning zones. Spenco Medics™ Diabetic+ Insole features a Plastazote® top cover to reduce friction and cushion the sensitive diabetic foot.


The anatomy of a Spenco Medics™
Orthotic Insole

Anatomy of a Spenco Medics™ Orthotic Insole diagram
  1. 3-POD
    3-POD™ GRF MODULATION SYSTEM

    Interchangeable pods of different densities piston through the semi-flexible cradle to modulate ground reaction forces. Select a firm medial and soft lateral heel pod to reduce excessive pronation forces around the tarsus.
  2. DEEP HEEL CUP

    Helps to stabilize the rearfoot.
  3. TOTAL SUPPORT® TECHNOLOGY

    Semi-flexible Cradle redistributes GRF across the whole plantar surface.
  4. ADDITIONAL PODS FOR CUSTOMIZATION

    Varying density heel and mid-foot pods allow for in-office prescription modifications.
  5. FIRST METATARSAL HEAD CUT OUT

    Promotes improved first-ray function.
  1. DEEP HEEL CUP

    Helps to stabilize the rearfoot.

Spenco Medics™ Sample Prescriptions

LOW PRONATION FORCES

Use to the lower-density pod set as shown.

Dress insole - low density, Sport insole - low density
Dress insole - low density
DRESS INSOLE
Sport insole - low density
SPORT INSOLE

MODERATE PRONATION FORCES

Use the higher-density pod set as shown.

Dress insole - high density, Sport insole - high density
Dress insole - high density
DRESS INSOLE
Sport insole - high density
SPORT INSOLE

HIGH PRONATION FORCES

Use the lower-density pods on the
lateral heel and mid-foot, and the
highest density pod on the medial heel.

Dress insole - low density, Sport insole - highest density
Dress insole - low density
DRESS INSOLE
Sport insole - highest density
SPORT INSOLE

NEUTRAL BALANCE:
EQUAL DUROMETER TO ALL THREE AREAS

Use the higher-density pod set as shown.

Dress insole - low density, Sport insole - neutral density
Dress insole - low density
DRESS INSOLE
Sport insole - neutral density
SPORT INSOLE

References:
  1. Nigg BM, Khan A, Fisher V, Stefanyshyn D: Effect of shoe insert construction on foot and leg movement. Sci Sports Med Exerc. 1998 Apr;30(4):550-5).
  2. Stacoff A, Reinschmidt C, Nigg BM, van den Bogert AJ, Lundberg A, Denoth J, Stüssi E.: Effect of foot orthoses on skeletal motion during running, Clin Biomech (Bristol, Avon), 2000 Jan;15(1):54-64 .
  3. Nigg BM, Cole GK, Nachbauer, W: Effects of arch height of the foot on angular motion of the lower extremities in running,. J. Biomechanics, 1993, Aug;26(8):909-16.
  4. Cashmere T, Smith R, Hunt R: Medial longitudinal arch of the foot: stationary versus walking measures. Foot Ankle Int. 1999 Feb:20(2):112-8.
  5. Hededus EJ, Cook C, Fiander C, Wright A: Measures of arch height and their relationship to pain and dysfunction in people with lower limb impairments. Physiother Res Int. 2010 Sep;15(3):160-6. doi: 10.1002/pri.459.
  6. Nakhaee Z, Rahimi A, Abaee M, Rezasoltani A, Kalantari: The relationship between the height of the medial longitudinal arch (MLA) and the ankle and knee injuries in professional runners. Foot (Edinb) 2008 Jun; 18(2): 84-90. doi: 10.1016/j.foot 2008.01.04. Epub 2008 Mar 18.
  7. LLahi, OA, Hohl, HW 3rd: Lower extremity morphology and alignment and risk of overuse injury. Clin. J Sports Med. 1998 Jan:(8)1: 38-42.
  8. Williams DS, McClay DI, Baitch SP: Effect of inverted orthoses on lower-extremity mechanics in runners. Med Sci Sports Exerc. 2003, Dec;35(12):2060-8.
  9. Kirby KA, Green DR: Evaluation and Nonoperative Management of Pes Valgus, pp. 295–327. In DeValentine S.(ed.), Foot and Ankle Disorders in Children. Churchill-Livingstone,New York, 1992.
  10. Kirby KA: Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997–2002. Precision Intricast, Inc., Payson, AZ, 2002.
  11. Dedieu P, Drigeard C, Gjini L, Dal Maso, F, Zanone PG: Effects of foot orthoses on the temporal pattern of muscular activity during walking. Clin Biomech (Bristol, Avon) 2013 Aug;28(7):820-4.
  12. Anthony, RJ: Spenco Total Support Insoles: A Step Ahead of the Paradigm Shift. Spenco Spotlight, Newsletter, October, 2013. http://www.multibriefs.com/briefs/cb-spenco/paradigm2.pdf
  13. Fuller EA, Kirby KA.: Subtalar joint equilibrium and tissue stress approach to biomechanical therapy of the foot and lower extremity. In Albert SF, Curran SA (ed.): Biomechanics of the Lower Extremity: Theory and Practice, Volume 1. Bipedmed, LLC, Denver, 2013, pp. 205-264.
  14. Anthony, RJ: Should “arch support” be the primary objective in the treatment of pronated feet? Spenco Spotlight, Newsletter, March 2014. https://www.spenco.com/article.aspx?rid=181&Prodid=0&Catid=186&cid=
  15. Spooner SK, Smith DK, Kirby KA: In-shoe pressure measurement and foot orthosis research: a giant leap forward or a step too far? J Am Podiatr med Assoc. 2010 Nov-Dec;100(6):518-29
  16. Griffiths I: The myths of foot orthoses The Sports Physio, 2013, Sept 29. https://thesportsphysio.wordpress.com/2013/09/29/the-myths-of-foot-orthoses-a-guest-article-by-ian-griffiths