EP3364803A1

EP3364803A1 - Midfoot-equipped sole for arch support and plantar pressure redistribution

Info

Publication number: EP3364803A1
Application number: EP16760563.3A
Authority: EP
Inventors: Maria Arcelina MARQUES; Nuno Viriato MARQUES RAMOS; Mário Augusto PIRES DE VAZ; Andreia Manuela CRESPO FLORES; Cátia Sofia NEVES MARTINS; Bruno Ricardo BARRETO GUEDES DA SILVA
Original assignee: Ropar - Fabrico De Calcado Ortopedico SA
Current assignee: Ropar - Fabrico De Calcado Ortopedico SA
Priority date: 2015-08-27
Filing date: 2016-08-19
Publication date: 2018-08-29
Also published as: PT108790A; WO2017034429A1

Abstract

The invention stated herein concerns a solution for shoe soles which are adaptable to plantar arch morphology. The solution is essentially characterized by combining. Into a single sole. Arch support (4) internally as an integral component of the sole (2) and an insert (1) having a smaller young's modulus than that of the remaining sole (2) externally as an integral component of the sole and confined to the midfoot region (3). This combination of characteristics, which increases the contact area between the foot and the shoe, at the insert of the sole, provides for a more effective damping of plantar forces and leads to a more efficient solution regarding the redistribution and decrease of the maximum forces that act in the midfoot region.

Description

DESCRIPTION

MIDFOOT-EQUIPPED SOLE FOR ARCH SUPPORT AND PLANTAR

PRESSURE REDISTRIBUTION"

Scope of the invention

The invention described herein concerns soles which can be adjusted to different types of feet (concave, normal and flat) , thereby granting support of the plantar arch by means of suitable internal geometry and allowing for a redistribution of the forces applied to the foot. Conversely, the use of a more flexible material in the midfoot region reduces the maximum force applied during contact of the foot with the ground. As a result, the proposed sole adapts to the foot, equally distributes plantar pressure and reduces the maximum force applied to the plantar region.

Previous technique

The design and drawing of shoes with different characteristics has been a growing concern of the larger companies in this field, taking into account the diversity of models currently on the market and their different purposes.

Orthopedic shoes tend to minimize the more frequent foot pathologies without taking the morphology of each person's feet into account, which may produce an improvement in a certain population but not perform in the same manner with regards to another. On the other hand, the athletic footwear market is a good example of this occurrence, where technology and scientific knowledge combine towards improvement of the products and the way in which they meet the specific needs of the user.

A wide variety of published studies are based on the development of insoles or orthoses, with the purpose of decreasing plantar pressure either locally or throughout the entire plantar surface. Both solutions always comprise an intermediate layer of material between the foot and the sole [1] . The more common local orthoses are designed to dampen the more intense plantar pressures occurring in the metatarsal area and in the heel [2,3]. There are also commercial solutions available which incorporate in the same insole or orthosis regions with differentiated materials to promote an equally differentiated dampening along the plantar surface.

Regarding soles, however, the main concern is centered around the material's hardness, durability, flexural strength and characterization of the friction coefficient for different types of pavement, i.e. it essentially concerns the material employed and the external design of the sole. The Arcopedico product stands out due to its incorporation of a previously patented (patent no. 47707) double arch system in the midfoot region, thereby reinforcing support of the plantar arch.

An orthosis, provided by a longitudinal arch support mechanism, resists the effect of load transferral towards the medial structures of the foot. With the appropriate mechanism, a significant decrease in deformation of the plantar fascia, which is under strain when the foot is overloaded, should occur. In prior studies performed by Kogler et al . (1995-1996), relative to the assessment of the plantar fascia's deformation, it was proven that the longitudinal arch support mechanism of a plantar orthosis, classified as flexible, is effective in preventing flattening of the arch. In this same study, three different user conditions were evaluated: barefoot, wearing shoes (lacking arch support) and wearing orthosis-equipped shoes. The differences between the first two conditions were insignificant; however, the deformation measured in the plantar fascia decreases significantly with the condition of the user wearing orthoses-equipped footwear vs. simple footwear .

As far as is currently known, there has been no recorded attempt of a shoe sole design integrating a different material in its external midfoot region associated with a double arch support geometry and internal geometry adaptable to the foot .

Brief description of the drawings

The following description is based on the attached drawings which, including but are not limited to, represent: In Figure 1 - Schematic illustration of the foot on the sole. The sole is comprised of the insert (1) and of the component (2) which represents the remaining part of the sole; the arch support (4) is represented in cross-section view (in accordance with section A-A) and its localization in the midfoot is also shown (3) .

In Figure 2 - Representation of 3 views of the insert (1) located in the midfoot region and providing double arch support, including dimensional identification, in which (a) corresponds to the height of the insert (1) in the posterior view, (b) corresponds to the height of the insert (1) in the anterior view and (c) corresponds to the length of the insert (1) . The B-B section, which results from a longitudinal cut, is also represented.

Detailed description of the invention

The original Arcopedico sole, which is characterized by a double arch system in the midfoot region (3), is the base model for the midfoot-equipped sole with arch support and plantar pressure redistribution. The changes introduced, which justify the invention at issue, allow for improving plantar arch support (4) and plantar pressure distribution in the midfoot region (3) .

This sole, as the object of the invention at issue, is considered as a hybrid sole comprised of two polymeric compounds, whose base material is a polyurethane having a Young's modulus between 4-10 MPa depending on the ratios used in the mixture, and whose insert (1), specified in Figure 1, represents the midfoot region with a Young's modulus at least ten times less than that of the remaining sole (2) . Young's modulus, relative to the materials, determines the manner in which these materials respond to external loads. A material with a smaller Young's modulus allows for greater flexibility and, consequently, a decrease of normal strains (plantar pressures) . In this case, the loads to which the sole is subjected correspond to the subject's weight. In this way, it is easily possible to obtain a solution combining different damping characteristics by using both materials with different elastic properties. In the studies performed, for a material having a Young's modulus of 0.2 MPa in the sole's insert, a reduction of plantar pressures, between 30 to 60%, was verified along a longitudinal line in the midfoot, as shown in chart I below:

Chart I

Moreover, along a cross - sectional line in the midfoot, the reduction measured was found to be between 30 and 50%, as shown in chart II below:

DISTANCIA i mm

Chart II

Therefore, in the midfoot region (3), or central region of the sole, which is defined by the area located between the metatarsus and the calcaneus as shown in Figure 1 (where the insert (1) is also located) , besides having verified a decrease in maximum values, the graphs exhibit a tendency for the uniformization of the pressures in the areas of interest, namely at the lateral region of the plantar arch.

The insert (1) represented in Figure 2 is characterized by having the same external double arch geometry as the Arcopedico sole, With heights (a) and (b) of 17 + 1 mm and 3 ± 1 mm, respectively, and a length (c) of 70 + 2 mm.

Another differentiating factor of the sole pertaining to this invention is the arch support (4) located in the internal medial region, as shown in Figure 1. This solution was designed to improve support of the medial longitudinal arch by increasing the contact area between the internal part of the sole and the plantar surface. Due to the effects of the individual's body weight, a natural flattening of the arch occurs, which becomes more pronounced as age and time advance as a result of a loss of elasticity of the tissue [3,4] . As a consequence, there is a greater probability of the appearance of plantar pains and fatigue. This situation becomes more critical when associated with an overweight factor.

Therefore, the shape of the arch support allows for adaptation to the morphology of the medial arch from the calcaneus to the metatarsus.

In general, feet can be grouped into three categories: flat, normal and concave. The main characteristic that distinguishes them is the height of the medial arch, in which the former exhibits lesser height and the latter a greater height. Because of this, a foot with more greatly pronounced arch requires greater supporting height. In accordance with the performed study, it was verified that the maximum height of the medial longitudinal arch, a characteristic of concave feet is, on average, of 15 + 1 mm and, for flat feet is of 10 ± 1 mm, in a population with an average age of 32 + 10 years.

This sole, comprising an arch support (4) and an insert

(1) having a Young's modulus smaller than that of the remaining sole (2) , provides for better adaptability of the whole midfoot (3) region, as a result of its plantar arch adaptable geometry, which redistributes the verified load, when compared to the Arcopedico sole. As a result, in the midfoot region, a uniformization of the distribution of plantar pressures can be observed when arch support is introduced, due to the greater contact area, as shown in chart III below, both for a Young's modulus of 8 MPa, relative to the Arcopedico sole, as well as for 0.2 MPa. Relative to the Arcopedico sole with this arch support, the introduction of the insert allows for a further decrease in the absolute pressure values in that region.

DISTA C1A (mm;

Chart III

The midfoot-equipped sole for arch support and plantar pressure redistribution pertaining to this invention allows for better arch support for different types of feet and better distribution of plantar pressures in the midfoot region. For this purpose, the sole is comprised of the following :

- Arch support allowing for a contour of the morphology of the medial arch from the heel to the metatarsus, having a maximum medial height of 15 ± 1 mm and with a geometry which is adaptable to the plantar arch and also adaptable to three different types of feet: flat, normal and concave;

- An insert (1) having a Young's modulus which is at least ten times smaller than the remainder of the sole (2) , at its perimeter, and contained within the midfoot region;

- Incorporation of the former two characteristics into a single sole, whose manufacturing process could contemplate the inclusion of the insert (1) manufactured either separately from a mold, during the manufacturing process of the remaining sole (2) or during the same manufacturing process but during different phases, depending on the mechanical properties of the insert, such as: density, Young's modulus and curing temperature, among others.

CAPTION

1 - Insert

2 - Sole

3 - Midfoot region

4 - Arch support MPa — Megapascal (Unit used when referring to an elasticity modulus or Young's modulus) .

GPa — Gig paSCal (Unit used when referring to an elasticity modulus or Young's modulus) .

CHART I - Chart comparing variations of the strains (plantar pressures) along a lateral longitudinal line at the surface of the foot, whose location is identified in the image for different values of Young's modulus for the insert, including the value corresponding to that of the Arcopedico sole .

CHART II - Chart comparing variations of the strains (plantar pressures) along a cross-sectional line in the midfoot region, whose location is identified in the image for different values of Young's modulus for the insert, including the value corresponding to that of the Arcopedico sole.

CHART III - Chart comparing the increase of the contact area in the midfoot region due to the introduction of arch support, with consequent uniformizat ion of the plantar pressures, in comparison with the same distribution and variation of pressures relative to the lack of arch support, for an insert having a Young's modulus of 0.2 MPa and 8 MPa, corresponding to an average value of Young's modulus of the Arcopedico sole.

References

[1] Cheung, J. T. , et al . A 3 -Dimensional Finite Element Model of the Human Foot and Ankle for Insole Design. 2006.

[2]Tsung, B. Y., et al . Effectiveness of insoles on plantar pressure redistribution. 2004.

[3] Werd, M., Knight, E.L. Athletic Footwear and Orthoses in Sports Medicine. 2010. Springer.

Treatment .

[4] Kogler, G.F., et al . Biomechanics of longitudinal arch support mechanisms in foot orthoses and their effect on plantar aponeurosis strain. 1996.

[5] Kogler, G.F., et al . In vitro method for quantifying the effectiveness of the longitudinal arch support mechanism of a foot orthosis. 1995.

Lisbon, August 19, 2016

Claims

CLAI MS

1. Midfoot-equipped sole for arch support and plantar pressure redistribution, based on the midfoot region double arch system, characterized by being a hybrid sole combining two polymeric compounds with different elastic properties, integrating :

- Arch Support (4) as an integral component of the sole

(2) internally adapting to the morphology of the medial arch from the calcaneus to the metatarsus;

- An insert (1) as an integral component of the sole's perimeter (2) and surrounded by the midfoot region (3) .

2. Midfoot-equipped sole for arch support and plantar pressure redistribution in accordance with claim 1, characterized by the insert having a smaller Young's modulus than the remainder of the sole (2) .

3. Midfoot-equipped sole for arch support and plantar pressure redistribution in accordance with claim 2, characterized by the insert (1) having a Young's modulus which is at least ten times smaller than the remainder of the sole (2), whose Young's modulus varies between 4 and 10 MPa.

4. Midfoot-equipped sole for arch support and plantar pressure redistribution in accordance with claims 1 and 3, characterized by the insert (1) having heights of (a) 17 + 1 mm and of (b) 3 + 1 mm, respectively, and a length (c) of 70 + 2 mm.

5. Midfoot-equipped sole for arch support and plantar pressure redistribution in accordance with

claim 1, characterized by the arch support (4) having a maximum medial height of 15 ± 1 mm for a concave foot.

6. Midfoot-equipped sole for arch support and plantar pressure redistribution in accordance with claims 1 and 5, characterized by the arch support (4) having a maximum medial height of 10 ±1 mm for a flat foot.

7. Midfoot-equipped sole for arch support and plantar pressure redistribution in accordance with claims 1, 5 and 6, characterized by the arch support

(4) having a cross - sectional extension towards the center of the sole.

Lisboa, August 19, 2016