Classifications

• • A—HUMAN NECESSITIES
  • A43—FOOTWEAR
  • A43B—CHARACTERISTIC FEATURES OF FOOTWEAR; PARTS OF FOOTWEAR
  • A43B17/00—Insoles for insertion, e.g. footbeds or inlays, for attachment to the shoe after the upper has been joined
  • A43B17/02—Insoles for insertion, e.g. footbeds or inlays, for attachment to the shoe after the upper has been joined wedge-like or resilient
• • A—HUMAN NECESSITIES
  • A43—FOOTWEAR
  • A43B—CHARACTERISTIC FEATURES OF FOOTWEAR; PARTS OF FOOTWEAR
  • A43B1/00—Footwear characterised by the material
  • A43B1/0009—Footwear characterised by the material made at least partially of alveolar or honeycomb material
• • A—HUMAN NECESSITIES
  • A43—FOOTWEAR
  • A43B—CHARACTERISTIC FEATURES OF FOOTWEAR; PARTS OF FOOTWEAR
  • A43B13/00—Soles; Sole-and-heel integral units
  • A43B13/14—Soles; Sole-and-heel integral units characterised by the constructive form
  • A43B13/18—Resilient soles
  • A43B13/181—Resiliency achieved by the structure of the sole
• • A—HUMAN NECESSITIES
  • A43—FOOTWEAR
  • A43B—CHARACTERISTIC FEATURES OF FOOTWEAR; PARTS OF FOOTWEAR
  • A43B17/00—Insoles for insertion, e.g. footbeds or inlays, for attachment to the shoe after the upper has been joined
  • A43B17/14—Insoles for insertion, e.g. footbeds or inlays, for attachment to the shoe after the upper has been joined made of sponge, rubber, or plastic materials

Definitions

• the invention relates to an insole for reducing peak pressures under a foot.
• insole may refer to a removable or fixed
• Reducing peak pressures under feet of various people may be desirable for various reasons. It is, for example, particularly desirable for people with diabetes. The reason is that high peak pressures under the feet of people with diabetes can result in diabetic foot ulcers. These ulcers may eventually lead to (partial) amputation of the affected lower limb. Keeping peak pressures below 200 KPa prevents ulcerations.
• Custom made insoles are commonly used. In the best situation these are based on a one time pressure measurement. Production processes like 3D printing and CAD have helped with decreasing production costs of these insoles. However, over time pressure spots change due to changes in the foot structure and the insole does not adapt to these changes.
• US2017348181A1 discloses an insole, which actually does adapt to changes in the foot structure over time.
• the insole known from US2017348181A1 even effectively adapts to changes in pressure spots, dynamically when the patient walks.
• This known insole is capable of changing along when pressure spots change during walking.
• this known insole is very complex, as well as very expensive. The reason is that this known insole has a layer of many modules, wherein each module has many co-operating parts and aspects, such as a deformable cushion with a cavity, a valve, a tank, a pressure sensor, and a feedback loop.
• WO 2018/115874 Al discloses an insole according to the pre-characterizing portion of appended independent claim 1 of the present disclosure. It is an object of the present invention to provide at least an alternative insole for reducing peak pressures under a foot, wherein the insole is effective to adapt to changes in pressure spots, dynamically when the patient walks, and wherein the insole is less complex and less expensive than the insole known from the above-mentioned US2017348181A1.
• the invention provides an insole according to the appended independent claim 1.
• Preferable embodiments of the invention are provided by the appended dependent claims 2-7.
• the invention provides an insole for reducing peak pressures under a foot, wherein the insole has an insole surface in
• the insole comprises a plurality of resilient supporting elements, which are distributed over the insole surface for resiliently supporting a foot in a supporting direction, which is transverse to the insole surface, and wherein, for each supporting element of said plurality of supporting elements, the supporting element has an undeformed condition, from which the supporting element is resiliently deformable under influence of an external compressive force, which is exerted on the supporting element in the supporting direction, the supporting element having a supporting surface for receiving said external compressive force, and wherein the supporting element returns into said undeformed condition in reaction to a condition in which said external compressive force vanishes, and wherein the supporting element comprises a resiliently collapsable buckling part designed to have a buckling behaviour such that:
• the buckling part resiliently collapses in the supporting direction in reaction to a condition in which said external compressive force exceeds a first force threshold
• the buckling part resiliently expands in the supporting direction in reaction to a condition in which said external compressive force falls below a second force threshold, which is lower than the first force threshold,
• the buckling part of the supporting element is formed by an elastically deformable circumferential buckling wall, which is extending circumferentially around a central axis of the supporting element, said central axis of the supporting element being parallel to the supporting direction, and
• the supporting element further comprises a main supporting portion, wherein said supporting surface is an outer surface of the main supporting portion,
• the main supporting portion in at least a sub-range along said central axis has a narrowing outer shape, such as for example a frusto- conically narrowing outermost shape, as seen in a direction away from said supporting surface,
• the circumferential buckling wall is on a side of the
• the circumferential buckling wall in at least a sub-range along said central axis is widening, such as for example conically widening, as seen in a direction away from said supporting surface.
• the terms“resilient” and“resiliently”, as used throughout the present document in relation to the above-mentioned supporting element, generally refer to the abihty of the supporting element to automatically spring back into shape after being compressed in the above- mentioned supporting direction. Said springing back is occurring towards the above-mentioned undeformed condition of the supporting element and is based on spring force provided by the supporting element itself.
• the term“buckling”, as used throughout the present document in relation to the above-mentioned supporting element, more particularly as used in relation to the above-mentioned resiliently collapsable“buckling” part having the above-mentioned “buckling” behaviour, is to be understood to mean: angularly bending as a result of a locally abruptly lower bending stiffness of the supporting element.
• the foot of the user will exert pressure on the insole, the pressure being distributed over the total number of supporting elements that are present.
• the resulting pressure distributed over the surface of an individual supporting element results in a compressive force proportional to the pressure and surface area of the supporting element. This compressive force causes the supporting element to buckle.
• the resiliently collapsable buckling part with its budding behaviour can be noncomplex, easy to produce, durable and reliable.
• each supporting element has the above-mentioned resiliently collapsable buckling part having the above-mentioned collapsing and expanding buckling behaviours in dependence of how the external compressive force behaves relative to the above-mentioned first and second force thresholds, and in combination with
• the insole according to the invention automatically and dynamically prevents local peak pressures by redistributing the pressures over a larger number of
• the insole according to the invention provides a highly effective dynamically self-adjusting pressure distribution for reducing peak pressures under a foot. Thanks to the above- mentioned narrowing outer shape of the main supporting portion and the above-mentioned widening circumferential buckling wall, the major feature of the invention, i.e. the supporting element as a whole, is realized in a compact, noncomplex, nonexpensive and reliable manner.
• said plurality of resilient supporting elements is an integrally manufactured one-piece structure.
• Such an integrally manufactured one-piece structure further contributes to the noncomplex and/or nonexpensive character of the insole.
• the one-piece structure may for example be made by a 3D printer. However, many various other manufacturing techniques are available as well, for example various 3D layerwise manufacturing technologies, injection moulding technologies, etc.
• an external pressure exerted on the supporting surface of the supporting element and a first pressure threshold for said external pressure are defined as to proportionally correspond, in terms of uniform pressure distribution over the supporting surface, to the external compressive force exerted on the supporting element and the first force threshold,
• said first pressure threshold is higher than 100 KPa and lower than 300 KPa; more preferably higher than 140 KPa and lower than 250 KPa; and yet more preferably higher than 180 KPa and lower than 200 KPa.
• these values of the first pressure threshold may reduce peak pressures under a foot to effective levels for preventing various foot problems, such as for example diabetic foot ulcers.
• the second force threshold is higher than 10% of the first force threshold and lower than 95% of the first force threshold; more preferably higher than 20% of the first force threshold and lower than 85% of the first force threshold; and yet more preferably higher than 30% of the first force threshold and lower than 75% of the first force threshold.
• the circumferential buckling wall in collapsed condition of the buckling part is received against the narrowing outer shape of the main supporting portion.
• the main supporting portion is a solid portion of the supporting element in the sense of not being hollow and not containing spaces or gaps. Such a solid portion further contributes to a favourable
• - transverse outermost boundary contours of the supporting element are defined as outermost boundary contours of the supporting element, respectively, as seen at least in said undeformed condition of the supporting element, and as seen in cross-sectional planes, which at different positions along said central axis, respectively, are transverse to said central axis, and
• the hexagonal shape provides the following advantages for providing predictable and reproducible buckling behavior of the supporting elements.
• the hexagonal shape allows for a maximum of six neighboring elements for each supporting element as opposed to for example a square shape where only a maximum of four neighboring elements may be achieved.
• the hexagonal shape advantageously maximizes the amount of neighboring elements that can take over the load from a supporting element, the hexagonal shape thus optimally redistributes the pressure over said neighboring supporting elements.
• the hexagonal shape also allows for an even distance between the outermost boundary contours of adjacent supporting surfaces thus providing a more uniform surface for more effectively redistributing the pressure, as opposed to for example a round shape which would leave more space in- between adjacent supporting elements.
• the hexagonal shape advantageously allows for the largest number of supporting elements distributed over het insole surface, thus maximizing the amount of supporting elements on the insole
• Fig. 1 shows, in a perspective view, an example of an embodiment of an insole according to the invention, wherein the supporting elements of the insole are in their undeformed conditions.
• Fig. 2 separately shows, in a perspective view, one of the plurality of resilient supporting elements of the insole of Fig. 1, wherein the shown supporting element is in its undeformed condition.
• Fig. 3A shows the supporting element of Fig. 2 in its undeformed condition, however this time in a cross-sectional plane which contains the central axis of the supporting element.
• Fig. 3B shows the situation of Fig. 3A again, however this time in a deformation condition of the supporting element in which an external compressive force is exerted on the supporting element in the supporting direction, wherein the external compressive force is lower than the above- mentioned first force threshold, so that the buckling part of the supporting element has not yet collapsed in the supporting direction.
• Fig. 3C shows the situation of Fig. 3B again, however this time in a condition in which said external compressive force exerted on the supporting element has exceeded said first force threshold, so that the buckling part of the supporting element has collapsed in the supporting- direction.
• Fig. 4 separately shows three mutually adjacent ones of the plurality of resilient supporting elements of the insole of Fig. 1, in a cross- sectional plane which contains the central axes of the three supporting elements, wherein the leftmost and rightmost of the three supporting elements are in the deformation condition of Fig. 3B, while the middle one of the three supporting elements is in the deformation condition of Fig. 3C.
• Fig. 5 shows a qualitative force/ displacement graph, which is typical for a supporting element, such as the specific supporting element of Fig. 2, wherein the graph depicts, for each considered standstill
• Fig. 6 shows a full-line graph and a broken-line graph, both as a function of time
• the full -line graph is an example of a qualitative force/time graph during a gait cycle performed by a person
• the full-line graph quahtatively indicating an imposed external compressive force exerted on a supporting element, such as the specific supporting element of Fig. 2, as a function of time
• the broken-line graph is
• the insole 1 illustrated by Figs. 1-6 is an insole according to each of the appended independent claims 1-7.
• the insole 1 has a large plurality of mutually identical supporting elements, generally indicated by the reference numeral 5.
• Three mutually adjacent ones of these identical supporting elements 5 have more specifically been indicated by the reference numerals 5A, 5B, 5C, respectively.
• the insole 1 of Fig. 1 further has a number of supporting elements, which are different from said mutually identical supporting elements 5. These different supporting elements are located along the outer
• Figs. 2-4 show the above-mentioned narrowing outer shape of the main supporting portion 9 of the supporting element 5, as seen in a direction away from the supporting surface 6. More specifically it is seen that, in the shown example, said narrowing outer shape is a frusto-conically narrowing outermost shape.
• Figs. 2-4 further show that the circumferential buckling wall 8 is widening in a manner as mentioned above. More specifically it is seen that, in the shown example, the circumferential buckling wall 8 is conically widening, as seen in a direction away from the supporting surface 6.
• Figs. 1-2 show the above-mentioned hexagonal shapes of the above-mentioned outermost boundary contours of the supporting element 5. More specifically, in the shown example said hexagonal shapes of the outermost boundary contours are occurring along the entire extension range of the supporting element 5 along the central axis 10.
• Figs. 3A-3C are illustrating the deformation behaviour of the supporting element 5, including the buckling behaviour of the collapsable buckling part 7, under influence of external compressive forces exerted on the supporting surface 6 of the supporting element in the supporting direction.
• the undeformed condition of the supporting element 5 as shown in Fig. 3A corresponds to a situation in which the external compressive force is absent.
• the condition of the supporting element 5 as shown in Fig. 3B corresponds to a situation in which the external compressive force is present, but does not exceed the first force threshold Ft, so that the buckling part 7 of the supporting element has only been deformed slightly, but has not yet collapsed. Accordingly, in Fig. 3B it is seen that the supporting surface 6 has been only shghtly displaced relative to its position (indicated by a broken line) that would correspond to the undeformed condition of the supporting element 5.
• the condition of the supporting element 5 as shown in Fig. 3C corresponds to a situation in which the external compressive force is present, and has exceeded the first force threshold Ft, so that the buckling part 7 of the supporting element has fully collapsed. That is, in Fig. 3B it is seen that the supporting surface 6 has been displaced over the maximum displacement D max relative to its position (indicated by a broken line) that would correspond to the undeformed condition of the supporting element 5.
• the buckling part 7 would resiliently expand in such manner that the supporting element 5 would attain a deformation condition simil r to that shown in Fig. 3B, or, if the external compressive force would fully vanish, the undeformed condition of Fig. 3A.
• Fig. 5 in order to further explain the deformation behaviour of the supporting element 5, including the buckling behaviour of the collapsable buckling part 7, under influence of external compressive forces exerted on the supporting surface 6 of the supporting element in the supporting direction.
• the resilient supporting element 5 has the ability to automatically spring back into shape after being compressed in the supporting direction. Said springing back is based on spring force provided by the supporting element itself. In that sense, the supporting element 5 is for example comparable with a compression spring.
• a compression spring has a“spring constant”, which defines a linear relationship between external compressive force and displacement.
• the resilient supporting element of the insole of the present invention on the other hand, has a totally different relationship between external
• FIG. 5 depicts the horizontal axis depicts the displacement of the supporting surface 6 of the supporting element 5, between 0 millimeter and D max , and wherein the vertical axis depicts the involved external compressive force, between 0 Newton and Fi.
• Fig. 5 shows that at the start of deforming the supporting element 5, there is a more or less linear relationship between external compressive force and displacement.
• the collapsable buckling part 7 starts to collapse, meaning that the resilient reaction force of the supporting element 5 drastically decreases in combination with a drastically increased
• first and second force thresholds F 1 and F2 are dependent on various design choices of the supporting element 5. For example, in the shown example it has appeared that these first and second force thresholds F 1 and F2 are highly
• Fig. 6 in combination with Fig. 4.
• the full-line graph could for example indicate an imposed external compressive force exerted on the supporting element 5B of Fig. 4 during a gait cycle performed by a person, wherein the broken-line graph of Fig. 6 indicates the correspondingly resulting displacement of the supporting surface 6 during said gait cycle.
• the supporting element 5B of Fig. 4 is in fully collapsed condition during a major part of the gait cycle.
• Fig. 4 illustrates that, when the supporting element 5B is collapsed, the neighbouring supporting elements, such as the elements 5A and 5C of Fig. 4, in unison will take over the load from the supporting element 5B. Accordingly, Figs.
• the insole according to the invention provides a highly effective dynamically self-adjusting pressure distribution for reducing peak pressures under a foot.
• Prototypes of the invention were manufactured by Fused Deposition Modelling 3D printers using thermoplastic polyurethane filament.
• Each supporting element 5 was manufactured with a height of 9 mm, a supporting surface 6 area of 1.46 cm2, a D m3 of 3.5 mm. Again, specific pressures over the supporting surface 6 will result in proportional values for the force thresholds.
• Different values for the main design parameters, said design parameters being wall thickness of the
• F 1 and Fa are the compressive force measured on the supporting surface, and the corresponding local pressure on the supporting surface at buckling (F i) and springing back (Fa). It is noted that these example values were identified by the inventors under laboratory conditions as providing good functionality, but other values for the wall thickness of the circumferential buckling wall 8, the angle between the circumferential buckling wall 8 and the central axis 10 may be identified with further development that also provide equal or better functionality.
• both the width direction 2 and the length direction 3 may also be curved directions, so that also the insole surface of the insole may generally be a two-dimensionally curved surface.
• the insole 1 of Fig. 1 is a deformable structure in both said directions.
• the outermost boundary contours of the supporting element 5 have hexagonal shapes.
• many various other shapes of such outermost boundary contours are also possible according to the invention, such as circular, oval, or otherwise rounded shapes, or triangular, square, or otherwise piecewise linear shapes, etc.
• one insole according to the invention may comprise different kinds of the supporting elements, having different shapes, collapsing properties, etc., instead of all the same supporting elements.
• the different kinds of supporting elements may be located in different zones along the support surface of the insole, respectively.
• an insole according to the invention may be designed both as a custom design and as an off-the-shelf design.
• an insole according to the invention may not only be beneficial for people with diabetes. It may also be beneficially applied to many various other boots or shoes, such as for example to many various sportsshoes.

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• Footwear And Its Accessory, Manufacturing Method And Apparatuses (AREA)

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• 2019
  • 2019-08-15 WO PCT/NL2019/050531 patent/WO2020055238A1/en not_active Ceased
  • 2019-08-15 EP EP19756030.3A patent/EP3849367B1/de active Active

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