Foot orthoses materials

doi:10.1054/foot.1999.0531

The Foot

Volume 10, Issue 1, March 2000, Pages 1-3

https://doi.org/10.1054/foot.1999.0531 Get rights and content

Abstract

The conservative management of foot disorders may involve the prescription of appropriate foot orthoses. Most foot disorders are mechanical in origin and mechanical therapy has a vital role in their management, even if surgery is not required. To provide the foot with an appropriate foot orthosis, it is necessary to look for an ideal material. This article provides information about the physical properties of the materials used in the construction of foot orthoses.

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Cited by (15)

Gradient optimization of multi-layered density-graded foam laminates for footwear material design
2020, Journal of Biomechanics
Citation Excerpt :
The properties of materials used in therapeutics shoes play a starring role in the effectiveness and the success of the footwear in satisfying clinical and biomechanical requirements. The characteristics of the utilized materials, including cushioning stiffness, have been directly linked to the biomechanics of redistribution and reduction of plantar loads during, for example, running or walking (Nicolopoulos et al., 2000; Healy et al., 2010; Chatzistergos et al., 2017; Giandolini et al., 2020). The need for effective cushioning is imperative for maximizing the pressure redistribution and reduction.
Several sports-related injuries and orthopedic treatments need the necessity of corrective shoes that can assuage the excessive pressure on sensitive locations of the foot. In the present work, we study the mechanical and energy absorption characteristics of density-graded foams designed for shoe midsoles. The stress-strain responses of polyurea foams with relative densities (nominal density of foam divided by the density of water) of 0.095, 0.23, and 0.35 are obtained experimentally and used as input to a semi-analytical model. Using this model, three-layered foam laminates with various gradients are designed and characterized in terms of their weight, strength, and energy absorption properties. We show that, in comparison with monolithic foams, significant improvement in strength and energy absorption performance can be achieved through density gradation. Our findings also suggest that there is not a single gradient that offers a superior combination of strength, energy absorption, and weight. Rather, an optimal gradient depends on the plantar location and pressure. Depending on the magnitude of the local plantar pressure, density gradients that lead to the highest specific energy absorption are identified for normal walking and running conditions.
Optimised cushioning in diabetic footwear can significantly enhance their capacity to reduce plantar pressure
2020, Gait and Posture
Citation Excerpt :
What is not clear however is how soft or how stiff they should be, and which parameters are important for defining their optimum stiffness. This gap in knowledge is reflected onto clinical practice too where material selection is still based on empirical or anecdotal evidence [9,10]. A finite element analysis aiming to provide some initial insight on optimum cushioning indicated that appropriate selection of material stiffness in footwear could significantly improve their pressure relieving capacity [11].
Plantar pressure reduction with the use of cushioning materials play an important role in the clinical management of the diabetic foot. Previous studies in people without diabetes have shown that appropriate selection of the stiffness of such materials can significantly enhance their capacity to reduce pressure. However the significance of optimised cushioning has not been yet assessed for people with diabetic foot syndrome.
Research question: What is the potential benefit of using footwear with optimised cushioning, with regards to plantar pressure reduction, in people with diabetes and peripheral neuropathy?
Plantar pressure distribution was measured during walking for fifteen people with diabetic foot syndrome in a cohort observational study. The participants were asked to walk in the same type of footwear that was fitted with 3D-printed footbeds. These footbeds were used to change the stiffness of the entire sole-complex of the shoe; from very soft to very stiff. The stiffness that achieved the highest pressure reduction relative to a no-footbed condition was identified as the patient-specific optimum one.
The use of the patient-specific optimum stiffness reduced, on average, peak pressure by 46% (±14%). Using the same stiffness across all participants lowered the footwears' capacity for pressure reduction by at least nine percentile points (37% ± 17%); a statistically significant difference (paired samples t-test, t(13) = −3.733, p = 0.003, d = 0.997). Pearson correlation analysis indicated that patient-specific optimum stiffness was significantly correlated with the participants’ body mass index (BMI), with stiffer materials needed for people with higher BMI (rs(14) = 0.609, p = 0.021).
This study offers the first quantitative evidence in support of optimising cushioning in diabetic footwear as part of standard clinical practice. Further research is needed to develop a clinically applicable method to help professionals working with diabetic feet identify the optimum cushioning stiffness on a patient-specific basis.
Dynamic rheological comparison of silicones for podiatry applications
2018, Journal of the Mechanical Behavior of Biomedical Materials
Citation Excerpt :
An important part of the features of foot ortoses depends on the material of which they are made. Pathology, age and weight are important factors to choose the right type of orthoses and the material of which they are made (Nicolopoulos et al., 2000). Interactions between the foot and the insole/shoe have been studied but more studies are still needed to clarify the biomechanical effects of such devices (Chen et al., 2010).
This work shows an effective methodology to evaluate the dynamic viscoelastic behavior of silicones for application in podiatry. The aim is to characterize, compare their viscoelastic properties according to the dynamic stresses they can be presumably subjected when used in podiatry orthotic applications. These results provide a deeper insight which extends the previous creep-recovery results to the world of dynamic stresses developed in physical activity. In this context, it shoulod be taken into account that an orthoses can subjected to a set of static and dynamic shear and compressive forces.
Two different podiatric silicones, Blanda-blanda and Master, from Herbitas, are characterized by dynamic rheological methods. Three kinds of rheological tests are considered: shear stress sweep, compression frequency sweep and shear frequency sweep, all the three with simultaneous control of the static force at three different levels. The static force represents a static load like that produced by the weight of a human body on a shoe insole. In a practical sense, dynamic stresses are related to physical activity and are needed to evaluate the frequency effect on the viscoelastic behavior of the material. It is considered that the dynamic stresses can be applied in compression and shear since, in practice, the way the stresses are applied in real life depends on the orthoses geometry and its exact location with respect to the foot and shoe. The effects of static and dynamic loads are individualized and compared to each other through the relations between the elastic constants for isotropic materials.
The overall proposed experimental methodology can provide very insightful information for better selection of materials in podiatry applications. This study focuses on the rheological characterization to choose the right silicone for each podiatric application, taking into account the dynamic viscoelastic requirements associated to the physical activity of user. Accordingly, one soft and one hard silicones of common use in podiatry were tested. Each of the two silicones exhibit not only different moduli values, but also, a different kind of dependence of the dynamic moduli with respect to the static load. In the case of the soft sample a linear trend is observed but in the case of of the hard one the dependence is of the power law type. Moreover, these samples exhibit very different Poisson's coefficient values for compression stresses lower than 20 kPa, and almost the same values for stresses above 40 kPa. That different dependence of the Poisson's ratio on the static load should also be taken into account for material selection in customized podiatry applications, where static and dynamic loads are strongly dependent on the individual weight and activity.
Evaluation of the pressure-redistributing properties of prefabricated foot orthoses in older people after at least 12 months of wear
2011, Gait and Posture
Citation Excerpt :
Although a survey in Australia indicated that podiatrists were six times more likely to prescribe customised orthoses over prefabricated orthoses [10], several recent studies have indicated that prefabricated orthoses may be equally effective as customised devices in the treatment of some foot conditions [11–13]. A potential limitation of many prefabricated foot orthoses is that they are generally constructed using soft or semi-rigid materials that deform more readily than the more rigid materials typically used for customised foot orthoses [14,15]. Consequently, the biomechanical effects of prefabricated orthoses may be lost as the material fatigues [16,17].
Foot problems are highly prevalent in older people. To treat such problems in this age-group prefabricated (‘off-the-shelf’) foot orthoses are frequently prescribed. However, such devices are susceptible to material compression and deformation, which may reduce their effectiveness over time. Therefore, the aim of this study was to compare the pressure-redistributing properties of new prefabricated orthoses to orthoses worn for at least 12 months. Thirty-one adults (10 males, 21 females) aged over 65 years (mean 75.4, SD 5.2) participated. Plantar pressure data were collected under the rearfoot, midfoot and forefoot using the Pedar^® in-shoe system while participants walked along an 8 m walkway wearing shoes only, new orthoses and old orthoses (orthoses were full length, dual-density prefabricated Formthotic™ devices). Compared to the shoe-only condition, both the new and old orthoses produced significant reductions in peak pressure and maximum force in the rearfoot with corresponding increases in force and contact area in the midfoot. Compared to the new orthoses, the old orthoses exhibited small but significant increases in peak pressure in the rearfoot (6%, p = 0.001) and maximum force in the rearfoot (5%, p < 0.001) and forefoot (2%, p = 0.032). These findings indicate that the prefabricated orthoses evaluated in this study are only slightly less effective at redistributing plantar pressure after at least 12 months of wear.
Manufacturing methodology for personalised symptom-specific sports insoles
2009, Robotics and Computer-Integrated Manufacturing
Citation Excerpt :
While there are contradictions over classification methods, there is a general agreement between professionals with regard to the important physical characteristics within orthotic fabrication. These include their response to temperature, elasticity, hardness, density, durability, flexibility, compressibility and resilience [16,31]. Density and hardness are of particular interest as it is these attributes that affect the impact attenuation of the device; a high-density material will have little cushioning and so will provide a rigid, often controlling structure whereas a material of low density will absorb shock.
Orthotic insoles are used for numerous applications; they can be prescribed to treat medical conditions such as rheumatoid arthritis and to maintain the health of the feet of diabetic patients. Orthotic devices are also extensively used in sporting activities and can be used for improving skeletal function, thus enhancing the biomechanical performance of the user and subsequently providing a more economical gait. This paper focuses on the manufacture of sports insoles and provides a methodology for the design and manufacture of a personalised symptom-specific sports (3S) insole.
The framework includes the biomechanical assessment methods required for the effective prescription of a personalised insole. The requirements of a functional insole should relate not only to the geometry and condition of the foot but also the application in which it will be used. Different sports are played using specialised footwear, on varying surfaces and using diverse movements and so require an alternative design regarding the geometry and materials used. Thus novel manufacturing methods are required and two examples are described, namely the cryogenic machining of soft foamed polymers to achieve suitable impact attenuation and the autoclaving of a carbon-fibre composite material to produce a slim, rigid design.
Development and Effectiveness Testing of a Novel 3D-Printed Multi-Material Orthosis in Nurses with Plantar Foot Pain
2023, Prosthesis

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LEADING ARTICLEFoot orthoses materials

Abstract

The manufacture and use of functional foot orthosis

Basel: Karger,

Shoe Insoles in the workplace

Orthopaedics.

Functional foot orthoses for athletic injuries

J Amer Pod Med Assoc

Inverted functional orthosis

J Amer Pod Med Assoc

An effective orthotic design for controlling the unstable subtalar joint

Orthotics & Prosthetics

Running shoes, orthotics and injuries

Sports Med

LEADING ARTICLE
Foot orthoses materials