Patent Application
20230048857
The present invention relates to a molded insole, designed to fight against venous stasis induced by venous insufficiency in a patient, and thus improve venous return.
The insole is specifically adapted to the morphology of a patient's foot, in particular a senior patient, suffering from venous insufficiency. It is designed for the uniform improvement of venous return, regardless of the patient's plantar morphology. It can be inserted or directly integrated into any type of footwear, such as stockings, tights, socks or shoes including flip-flops and sandals.
Venous insufficiency is characterized by dilation of the veins or deterioration of the anti-reflux valves. This pathology is common in elderly patients. A reflux sets in and causes an increase in blood pressure in the veins. The slowing of the velocity of blood circulation thus leads to the first signs of the disease. The blood that stagnates in a vein can then cause a breakdown of the vein wall, causing deformation and the appearance of varicose veins. Among the risk factors linked to this pathology can be cited, for example, heredity, gender, age, obesity, position at work, pregnancy, menopause, and plantar dysmorphisms. In a known way, venous return can be improved by wearing insoles with variations in density.
Document EP 0 971 606 discloses an insole comprising several cushion-shaped layers configured to improve venous return. These layers are each separated into several plate-shaped fields juxtaposed in the transverse direction with respect to the insole axis. The layer forming a bump at the internal lateral arch sits on the base of the insole and is optional.
Document WO 2011/135278 discloses a plastic insole having zones for reducing pressure, which include orifices having less rigidity. This insole also increases blood flow and circulation in the foot.
Document WO 2011/017174 Al discloses an insole for improving comfort, in particular when running and walking. The insole comprises three portions attached to a central base, namely an external lateral arch, an internal lateral arch and a portion opposite the heel. The portion opposite the heel has a greater hardness than the base and the external lateral arch, which, themselves, have a greater hardness than the internal lateral arch. Each of the elements is manufactured separately then associated with the central base by conventional gluing techniques, for example.
The object of the invention is to propose a new insole to fight against venous stasis induced by venous insufficiency.
To this end, the invention relates to a molded insole, comprising a base, an internal lateral arch that is provided to accommodate the arch of the foot and that is raised relative to the base, and at least one hard region that is integrated into the base, having a hardness equal to or greater than that of the base. This insole is characterized in that the base and the internal lateral arch constitute a single, mono-material part. The base extends, in practice, over the entire surface of the foot with the exception of the portion occupied by the internal lateral arch.
In addition, and according to another advantageous characteristic, the base is configured so that its upper surface does not undergo deformations in contact with the hard regions at the time of its integration after molding. In other words, the upper surface of the insole is smooth in the sense that it does not have any bumps next to the hard regions.
In practice, and as will be explained later, the hard regions are integrated into hollow chambers formed in the thickness of the base and opening onto the underside of said base. In other words, the lateral arch does not contain an integrated hard region within the meaning of the invention.
Thus, the insole is simpler and more economical to manufacture, due to the use of a single material to produce the base and the internal lateral arch of the insole, and the fact that the base and the internal lateral arch constitute a single part, compared to bi-material insoles and/or insoles integrating an added arch, as is the case, for example, in document WO 2011/017174 A1. In addition, the insole according to the invention is designed to adapt easily to each type of foot, flat, hollow or physiological.
The internal lateral arch is designed to accommodate the arch of the patient's foot. This configuration promotes venous return by compressing the plantar venous reservoir when walking, thanks, in particular, to the raised position of the internal lateral arch, formed projecting from the base.
Preferably, the internal lateral arch has a volume adapted to the volume of the patient's arch, in particular in the case of dysmorphia.
According to the invention, the thickness of the internal lateral arch corresponds to the thickness of mono-material constituting said arch. In practice, this thickness decreases from the center of the insole towards the inside of the insole. In other words, it decreases substantially from the center of the insole towards its periphery, on the inside of the foot.
The volume of the arch of the foot corresponds to the volume between the upper side of the insole and the plane extending the lower surface of the base under the internal lateral arch.
The correct positioning of the volume of the internal lateral arch on the insole is guaranteed by matching, from the rearmost point of the insole, the geographical location of an anatomical reference point taken on the arch of the foot with respect to the rear of the foot. This anatomical reference point is, in practice, the highest elevation point of the arch of the foot, i.e., corresponding to the maximum hollow formed in the arch of the foot between the underside of the base and the underside of the arch.
The internal lateral arch is defined by a virtual line corresponding to the maximum thickness of the insole for each of the vertical cross sections of the insole in the direction of the width of the insole.
The thickness of the insole increases from the external side of the insole towards the internal side of the arch to reach its maximum thickness along this virtual line. From this maximum thickness, the thickness of the insole decreases again from the external side of the insole towards the internal side of the arch.
The thickness of the insole increases along this virtual line from its 2 extremities to reach a maximum value near its center. In other words, the insole reaches a maximum thickness approximately halfway between the 2 ends of the virtual line.
Preferably, the volume and position of the internal lateral arch are determined according to three parameters: the gender of the patient; the patient's shoe size; and the morphology of the patient's foot.
On this basis, the morphology parameter of the patient's foot defines three possibilities: flat, hollow or physiological foot.
The insoles differ from each other for these 3 types of morphology by their maximum thickness at approximately halfway between the 2 ends of the virtual line defining the internal lateral arch.
As mentioned before, this thickness subsequently decreases:
According to the invention, the maximum thickness of the insole is 5.6±0.2 mm for a flat foot, 8.4±0.4 mm for a hollow foot and 8.8±0.2 mm for a physiological foot.
Preferably, the internal lateral arch has a curved lower surface forming a hollow with respect to the lower plane of the base, and a curved upper surface forming a projection with respect to the upper plane of the base.
Similarly, and in practice, the lower surface of the internal lateral arch has a greater slope than the upper surface of the arch.
In the embodiment where the hardness of the hard regions is greater than that of the base, the base may have a hardness between 22 and 50 on the Shore A scale depending on its thickness. The hardness of elastomers may be measured according to ISO 868/DIN 53505/ASTM 2240 standards. The base may have a density between 120 and 465 kg/m3 depending on its thickness.
In practice, and always in this embodiment, the hard regions may have a hardness between 53 and 58 on the Shore A scale, preferably 55 on the Shore A scale. The hard regions may have a density between 494 and 690 kg/m3, preferably between 570 and 610 kg/m3, for example 590 kg/m3.
For example, the hard regions may be made of 95% polyurethane and 5% carbon foam, while the part formed by the base and the internal lateral arch may be made of 100% polyurethane foam.
More generally, the insole may be made of all types of polymers or natural materials, pure or as a mixture, containing or not containing fillers or additives providing additional properties of the anti-odor type.
The insole may include a top layer covering the base and the internal lateral arch. This upper layer constitutes an accommodating surface for the foot resting on the insole, as well as a protective element. It thus makes it possible to avoid direct contact between the insole and the arch of the patient's foot and to improve comfort and hygiene when wearing the insole. This layer is made of flexible material, for example made from a composition of 90% microfiber polyamide and 10% polyurethane.
The applicant found that particularly advantageous results were obtained in terms of venous return when the hardness of the insole, in the parts of the base without a hard region, measured on the upper side of the insole and over its entire thickness, was between 30 and 56 on the Shore A scale depending on the thickness of the insole, and that the hardness of the insole, in the parts of the base incorporating the hard regions, measured under the same conditions, was between 65 and 77 on the Shore A scale depending on the thickness of the insole.
Thus, the invention also relates to a molded insole, comprising a base and an internal lateral arch provided to accommodate the arch of the foot, raised relative to the base, the base integrating hard regions. This insole is characterized in that the base and the internal lateral arch of the insole constitute a single mono-material part, advantageously covered with an upper layer over its entire surface, and in that:
The hardness of elastomers may be measured according to ISO 868/DIN 53505/ASTM 2240 standards.
According to the invention, the hardness may vary from one point to another on the surface of the insole within the ranges mentioned above.
In the present application, the limits of each density or hardness value range are included in the range.
According to the invention, the hard regions are formed by inserts integrated into the base. In practice, the base has chambers in which the hard regions are inserted. Thus, the insole has a smooth surface, i.e., an upper surface containing no localized extra thickness next to the hard regions. This makes it possible not to modify the proprioception sensations of the foot.
Preferably, the hard regions are laid out in the open air under the base. In other words, the hard regions are not covered by an additional layer of material. This reduces the time and cost of manufacturing the insole. Similarly, and still according to the invention, the hard regions are flush with the lower surface of the base and are, therefore, not projecting from the lower surface of the base.
As mentioned above, the results on venous return are even more convincing in the hardness ranges mentioned above and measured on the upper side of the insole.
A person skilled in the art will be able to determine the nature of the materials of the base and the hard regions to be implemented, as well as the compressive force to be applied to the base at the time of molding, in order to obtain the hardness within the ranges described.
The present invention also relates to a footwear item, for example stockings, tights, socks or shoes including flip flops and sandals, comprising an insole as defined above.
The insole may constitute a distinct element of the footwear item, i.e., the insole may be placed at the bottom of the footwear item to wear it. Alternatively, the insole may be directly integrated into the footwear item. This allows relatively varied uses of the insole.
The insole may be adapted for a flat, hollow or physiological foot. Within the meaning of the invention:
The CSI is the Chippaux Smirak Index, representing the ratio between the minimum width of the footprint at the arch of the foot (DC length) and the maximum width of the footprint at the metatarsals (AB length), as shown in
The index is defined by the formula: CSI=(DC)/(AB)×100.
The invention also relates to a manufacturing method of an insole as mentioned above. The process includes the following steps:
Advantageously, step c) of molding the preform is carried out by compressing a mono-material part of constant thickness, hardness and density in a mold, the mold being in shapes intended to configure the base so that its upper surface does not undergo deformations in contact with hard regions.
According to a particular embodiment, step c) may first comprise a step of laminating a strip corresponding to the upper layer over the entire surface of the mono-material strip.
According to a particular embodiment, the finishing step e) may consist in cutting out the outline of the pre-insole in order to obtain the insole in its final state.
Alternatively, the insole may be manufactured by other techniques, for example by 3D printing.
The insole may receive design elements by screen printing, pad printing, transfer, or any other technique (for adding a logo, marking areas, various style effects).
The insoles may be mass-produced, including different sizes and different morphologies (flat foot, hollow foot or physiological foot), depending on the gender of the patient. Alternatively, the insoles may be custom-made, depending on the morphology of the patient's foot.
The invention will be better understood on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:
The insole (1) comprises a base (10), an internal lateral arch (20) raised relative to the base (10), four hard regions (30 (31, 32, 33, 34)) having a hardness greater than that of the base (10), and a top layer (40).
According to the invention, the base (10) and the internal lateral arch (20) of the insole constitute a single, mono-material part (2). Thus, the insole (1) is simple and economical to manufacture, due to the use of a single material to make the base (10) and the internal lateral arch (20) of the insole (1).
The base (10) is substantially planar.
The internal lateral arch (20) constitutes a portion of the insole (1), provided to accommodate the arch of the patient's foot. This configuration promotes venous return, thanks, in particular, to the raised position of the internal lateral arch (20), formed projecting from the upper side of the base (10). The internal lateral arch (20) has a curved shape so as to match the shape of the arch of the patient's foot.
As shown in
According to the invention, the insole reaches a maximum thickness approximately halfway between the 2 ends of the virtual line defining the lateral arch designated “MAX” in
The thickness of the insole increases from the external side of the insole towards the internal side of the arch to reach its maximum thickness along the virtual line. From this maximum thickness, the thickness of the insole decreases again.
The internal lateral arch is defined by this virtual line corresponding to the maximum thickness of the insole for each of the vertical cross sections of the insole, in the direction of the width of the insole. These values are designated MAX1, MAX1, MAX2, MAX2′ etc. and gradually increase to the MAX value.
The arch (20) has a curved lower surface (21) forming a hollow with respect to the lower plane (P11) of the base (10). The arch (20) has a curved top surface (22) projecting from the top plane (P12) of the base (10). The lower surface (21) has a steeper slope than the upper surface (22) of the arch (20). This allows the insole to match the morphology of the arch of the foot.
In practice, the plantar venous reservoir is positioned in the lateral plantar veins located deep at the arch of the foot.
By following the shape of the arch of the foot, the internal lateral arch (20) acts as a “pump” for the deep activation of the lateral plantar veins.
This action is particularly useful in case of dysmorphism of the patient, characterized by a deformation of the arch of the foot leading to poor functioning of the plantar pump linked to the anatomical modifications. The insole (1) then allows to correct this problem.
The hard regions (30) are spaced apart along a longitudinal direction of the insole (1). These hard regions (30) correspond to the foot support points: sole of the foot (central zone of the foot), metatarsus (forefoot), heel and tarsus (rearfoot). The specific location of the hard regions (30) allows to distribute in a homogeneous manner the weight of the body while in a standing position from these points subject to strong stresses over the entire surface located under the foot. Moreover, the hard regions (30) constitute a reinforced protection of these sensitive points.
The hard regions (30) are auxiliary activators for improving venous return. Due to their location, and their hardness equal to or greater than that of the base (10), the hard regions (30) act at the surface of the soles of the feet to create a “2nd pump” effect, as a complement to the “1st pump” effect created by the internal lateral arch (20) acting in depth to activate the lateral plantar veins.
This effect is reinforced by the fact that the base is configured so that its upper surface does not undergo deformations in contact with the hard regions at the time of manufacture of the insole, as will be seen later. Therefore, the surface of the insole is smooth.
More particularly, the hard regions (30) may be formed by inserts (31, 32, 33, 34) integrated into chambers provided in the base (10). This integration may be done, for example, by laminating the inserts (31-34) on the base (10).
The inserts (31-34) act as reinforcements, arranged on the underside of the insole (1) and corresponding to the bearing points of the patient's foot on the insole.
The inserts (31-34) have different geometric shapes, corresponding to the surface of the patient's bearing points:
As shown in
The internal lateral arch (20) of each insole (1) is designed according to the gender, size and morphology of the patient's foot (flat foot, hollow foot or physiological foot). Advantageously, the internal lateral arch (20) is designed with a volume specifically adapted to the volume of the patient's arch of the foot, in particular in the event of dysmorphia. This volume may be determined by acquisition by 3D scanner. The volume of the internal lateral arch (20) is then the 3D shape of the arch of the foot. The correct positioning of the volume of the internal lateral arch (20) on the insole (1) is guaranteed by matching, from the rearmost point of the insole (1), the geographical location of an anatomical reference point taken on the arch of the foot in relation to the rear of the foot. Preferably, this anatomical reference point is the point of highest altitude of the arch of the foot, i.e., corresponding to the maximum hollow formed in the arch of the foot.
As the cross section VI shows, the insole (1) has a constant thickness at the heel, in practice of the order of 3.5 mm, then gradually increases near the virtual line, appearing in a solid line, then reaches the virtual line at the MAX1 value greater than 3.5 mm. The thickness of the lateral arch then decreases towards the inside of the insole.
The cross section VII corresponds to the section of the insole with the maximum thickness. It is designated MAX.
The cross section VIII corresponds to a section of the insole with a constant thickness across its width, which means that this section does not contain the internal lateral arch. The thickness of the insole is constant here, in practice approximately 3.5 mm over its entire width.
As already stated, the insoles are different depending on the morphology of the patient's foot. What changes from one insole to another is essentially the MAX maximum thickness that said insole may reach, in practice 5.6±0.2 mm for a flat foot, 8.4±0.4 mm for a hollow foot and 8.8±0.2 mm for a physiological foot.
The insole (1) preferably comprises an upper layer (40), covering the mono-material part (2), to improve the comfort and hygiene of the insole (1). The upper layer (40) constitutes an accommodating surface for the foot resting on the insole (1). To mass-produce a range of insoles (1), one mold is available per gender and per size (for example, 36 to 41 for women; 39 to 45 for men), and per type of arch (flat, hollow or physiological).
Clinical trials were carried out to test the insole (1) according to the invention as to its effectiveness on improving venous return.
The insoles (1) tested comprise a base (10) of 100% polyurethane foam, with a hardness of 22-50 on the Shore A scale depending on its thickness, as well as hard regions (30) composed of a foam consisting of 95% polyurethane and 5% carbon, with a hardness of 56 on the Shore A scale.
In the parts free of hard regions measured on the upper side and over its entire thickness, the insoles have a hardness of between 30 and 56 on the Shore A scale depending on the thickness.
In the parts incorporating hard regions measured on the upper side and over its entire thickness, the base of the insoles has a hardness of between 65 and 77 on the Shore A scale depending on the thickness.
The hardness of the elastomers was measured according to ISO 868/DIN 53505/ASTM 2240 standards.
On the upper side, in contact with the foot, the insole is covered with an upper layer (40) composed of 90% polyamide microfiber and 10% polyurethane.
First, the effect of wearing a pair of molded insoles (1) on the velocity of venous return was compared to the effect obtained when not wearing these insoles (1). Also, the effect of wearing a pair of insoles (1) on postural stability in a standing position (eyes closed and eyes open) was compared to the effect obtained when not wearing these insoles.
A population of 75 subjects was divided into 3 groups of 25, depending on the type of foot: hollow, flat or physiological).
The tests were carried out to study four criteria:
For the first three criteria presented above, the study shows that wearing an insole (1) leads to a clear improvement in venous return with wearing an insole (1) between morning and evening, and a clear improvement of venous return at fixed time (e.g., evening).
In the tables below, the results obtained are expressed in percentages and show an average improvement of 49.9% for the 75 subjects, broken down into 55.95% for the flat foot group, 44.96% for the hollow foot group; 48.76% for the physiological foot group.
Table 1 below corresponds to the control test (without insole). Subjects 1 to 25 have flat feet, subjects 26 to 50 have hollow feet, and subjects 51 to 75 have physiological feet.
indicates data missing or illegible when filed
Table 2 below corresponds to the test with an insole according to the invention: The subjects are the same as for Table 1. Subjects 1 to 25 have flat feet, subjects 26 to 50 have hollow feet, and subjects 51 to 75 have physiological feet.
Thus, regardless of the type of foot analyzed (hollow/flat/physiological), the study demonstrates an improvement in hemodynamics obtained by wearing an insole (1) according to the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2001322 | Feb 2020 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/053382 | 8/19/2021 | WO |
