GB2447646A

GB2447646A - An apparatus that responds to the varying pressures applied to the foot of a subject during different activities

Info

Publication number: GB2447646A
Application number: GB0705094A
Authority: GB
Inventors: Emma Cowley; Anthony Achilles
Original assignee: Plymouth University
Current assignee: Plymouth University
Priority date: 2007-03-16
Filing date: 2007-03-16
Publication date: 2008-09-24
Anticipated expiration: 2027-03-16
Also published as: GB2447646B; WO2008113987A1; EP2136667A1; GB0705094D0

Abstract

An apparatus 2 that responds to the varying pressures applied to the foot of a subject during different activities, in particular walking, jogging and running, comprises a member 4 with a major surface 6 for contacting the plantar surface of the foot of the subject; and structures 10 for absorbing and reacting to various pressures in the foot whilst in use. The structures 10 preferably extend from the major surface 6 of the member 4 and may be in the form of frusto-conical units 12 extending upwards from the major surface 6 towards the foot of the user when in use, the units 12 being compressible under the action of pressure from the foot, the resistance of the units 12 to compression increasing progressively or stepwise as the unit 12 is compressed. The units 12 are preferably hollow and have an internal or external taper (see Figs 6 and 7) to provide the variable resistance to compression.

Description

Foot Orthosis Apparatus The present invention is directed towards an

apparatus that responds to the varying pressures applied to the foot of a subject during different activities, in particular walking, jogging and running.

The pressure experienced by the foot of a subject varies according to their activity.

When the subject is walking, light loads and impact are experienced by the foot.

When the subject begins to jog or run, however, the forces and impact experienced by the foot are higher. In order to absorb these forces, the foot needs a soft cushion when the subject is walking, and a more resistant platform when the subject is jogging or running.

Many items of footwear, in particular sports shoes, comprise soles with a structure or materials to cushion the impact of the foot of the user when in use. However, such soles do not have a varying resistance to the forces of impact of the foot of the user.

Thus, US 2001/0007180 discloses a shoe with a viscoelastjc interior liner. The liner comprises a viscoelastic substance assembled to a flexible and elastic film. The layer filters vibrations and impacts from the foot, while preserving the transmission of tactile sensations.

US 200410003513 discloses a gel insole for a shoe having lower toe and heel recesses with thin spring walls. Each recess has a pirulaity of thin, parallel spaced apart spring walls in the shape of a sinusoidal wave. The action of the walls is to absorb vibration and impacts. However, the wall structure presents the foot with a single resistance to load.

One attempt at providing a footwear item with a variable resistance to impact and vibration of the user's foot is the provision of a variable fluid-filled system in the footwear. Thus, US 5,444,926 discloses a reactive energy apparatus providing cushioning at the instep of a shoe. The apparatus comprises a body of fluid retained in a plurality of bladders in the sole of the shoe. A tube connects the bladders and allows the fluid to be displaced to accommodate and fit the foot of the wearer. A similar system is disclosed in JP 1284205. The fluid-filled systems are particularly difficult to manufacture and do not adequately present a variable resistance to the foot of the user when engaged in different activities.

A shoe insole is disclosed in US 2002/0144433 in which one or more acceleration-rate-sensitive, differentiated-softness bonded visoelastjc cushioning layers are bonded together. The variation in softness of the insole is said to be achievable using a single layer of uniformly characterized acceleration-ratesensjtive material with one softness behaviour nature, or by the use of several layers of materials of differing softness.

Finally, more recently, a mechanical system has been proposed. EP 1,530,913 discloses a tunable cushioning system for a shoe, in which one or more generally cylindrical cushioning inserts are disposed in the sole of the shoe. The inserts may be rotated to vary their cushioning properties and locked in one position, if desired by the user.

Accordingly, there is a need for a single apparatus that can respond to the forces applied to the foot and provide the soft cushioning required during walking, and a more resistant platform during jogging or running.

According to the present invention, there is provided an apparatus for responding to the varying conditions of pressure in the foot of a subject comprising; a member having a surface for contacting the plantar surface of the foot of the subject; and the member comprising structures for absorbing and reacting to various pressures exerted by the foot of the subject whilst in use, the structures providing a first resistance to lower impact forces applied by the foot to the structures and a second resistance to higher impact forces applied by the foot to the structures.

The apparatus comprises a member with a surface for contacting the sole of the foot of the subject and structures for absorbing and reacting to various pressures from the foot whilst in use. The structures may be disposed within the member or on one or both of the upper surface of the member, that is the surface contacting the plantar surface of the foot of the subject when in use, or the lower surface or underside of the member. A preferred embodiment is one in which the structures are disposed on the surface of the member in contact with the plantar surface of the foot of the user. The structures may extend or protrude from the surface of the member or may be recessed into the surface of the member, or a combination of the two, as discussed in more detail hereinafter.

The apparatus may be incorporated into a form of footwear, for example, the apparatus may be used to form an integral part of the sole of the footwear, such as a trainer or sports shoe. Alternatively, the apparatus may be a separate component that may be incorporated into the sole of the footwear. The apparatus may also be in the form of an insole, for insertion into the chosen footwear of the subject and moved from footwear to footwear, as required or desired.

The member is manufactured from a suitable material that is flexible enough so as to allow a large area of contact with the plantar surface of the foot. Suitable materials of construction for the member are known in the art and commercially available. The material is preferably polyurethane (PU), which may, or may not be filled in order to provide the required flexibility, softness and density. Suitable fillers for inclusion in the material are well known in the art and commercially available.

The member is of a suitably soft material, while being one that provides adequate support for the foot of the user and the structures of the apparatus. The member preferably provides a third resistance to impact, different to each of the first and second resistances to impact provided by the Structures.

The apparatus may extend under the entire plantar surface of the foot of the user, so as to contact the entire plantar surface. Alternatively, the apparatus may extend under a portion of the plantar surface.

Preferably, the apparatus extends under the calcaneus; this is the quadrangular bone at the back of the tarsus, also known as the heel bone. The apparatus preferably fits under the calcaneus in use and provides support for this bone by filling the space beneath it. The calcaneus is covered with a fat pad, commonly referred to as the heel.

In the area of the apparatus to be disposed beneath the calcaneus, the member is preferably of a softer construction than the remainder of the member. This may be achieved with a material that is softer than that of the body of the apparatus being comprised in the member, so as to provide cushioning for the padded surface of the calcaneus. Alternatively, the member may comprise a cavity in the region underlying the calcaneus in use. In one embodiment, the member comprises a cavity in this region, the cavity being filled with a suitably soft material having a lower resistance to impact. :* 20

In a preferred embodiment, the apparatus is preferably formed to fit solely under the heel portion of the foot. Alternatively the apparatus is larger in size in order to extend * under a further section of the foot or under the whole foot. "I

I

*. : 25 The apparatus features structures for absorbing and reacting to various pressures from the foot whilst the apparatus is in use. The structures are preferably disposed on the surface of the member in contact with the plantar surface of the foot of the user. The structures preferably protrude from the surface of the member.

The structures of the apparatus of the present invention are comprise a single material, shaped to provide a variable resistance to impact, depending upon the magnitude of the impact applied by the foot of the user. In this respect, being of a single material, the structures and the member containing them are easy to manufacture, for example by injection moulding techniques, well known in the art.

The StrUCtUreS gencrally each comprise a single, compressible unit. Each unit may be connected to one or more adjacent units by means of a buttress, to provide improved rigidity and prevent the structures becoming overly distorted by severe impacts. The unit comprises a generally upright configuration which may take a variety of shapes.

The upright configuration provides the unit with a longitudinal axis which is aligned with the expected direction of force to be applied by the foot of the user when in use, such that the pressure applied by the foot during use is directed along the central longitudinal axis of the unit. The unit is constructed to compress under impacts from the foot of the user and provide a different resistance to impacts, depending upon the size of the impact. In particular, the unit offers a first, relatively low resistance to compression for minor impacts and a second, higher resistance to compression when subjected to higher impact pressures. Most preferably, the unit provides a progressively increasing resistance to impact with increasing severity of impacts.

* The different resistance to compression under impact is achieved in the unit by the * 20 shape and configuration of the unit, in particular by a change in shape of the unit in the longitudinal direction. In particular, the unit is shaped such that the surface area of material being compressed by an impact from the foot of the user increases as the magnitude of the impact force increases. In one embodiment, the units are solid and have a generally tapered form externally, either stepwise or continuously tapered, * 25 preferably with the narrow end of the taper being closest to the foot of the user when in use and the wider end of the taper being most distant from the foot of the user. In an alternative arrangement, the unit is hollow having a cavity extending partially or completely along the longitudinal axis of the unit, with the change in impact resistance being provided by a change in the thickness of the wall of the unit. In this case, the wall thickness will increase, either step wise or gradually in the longitudinal direction, preferably away from the foot of the user, and the unit may be considered to have an internal taper. The units may take a variety of shapes, with preferred forms being pyramidal, conical, frusto-conical, domed, and cylindrical. The member may comprise units that are all of the same form or may comprise a mixture of different forms.

The structures are preferably disposed within the member so as to at least contact the areas of the plantar surface of the foot that are exposed to high impact pressures during the full range of activities expected from the user. In particular, the structures are preferably disposed in the region of the heel of the foot of the user.

The structures may be of a material having any suitable hardness to function properly.

It is preferred that the structures are formed from a material having a Shore Hardness of from 50 to 120, more preferably from 70 to 100, especially about 90.

The member comprising the structures is preferably of a softer material than the structures themselves. It is preferred that the member is formed from a material having a Shore Hardness of from 30 to 50, more preferably from 35 to 45, especially about 40.

The structures may be arranged in any suitable pattern or arrangement in the member.

For example, the structures may be arranged in a single line or a plurality of lines.

Alternatively, the structures may disposed in another geometric pattern or even randomly within the member. I.

* 25 In a further aspect, the present invention provides an item of footwear comprising an apparatus as hereinbefore described.

Embodiments of the present invention will now be described, by way of example only, having reference to the accompanying drawings, in which: Figure 1 is a representation of one embodiment of the apparatus of the present invention for use with the right foot from above; Figure 2 is a perspective representation of the apparatus for use with the right foot of Figure 1; Figure 3 is a cross-sectional view of the apparatus for use with the right foot along the line of arrow III of Figure 1; Figure 4 is a representation of the apparatus for use with the right foot of Figure 1 from the side along the line of arrow IV of Figure 1; Figure 5 is a perspective representation of a second embodiment of the apparatus of the present invention for use with the right foot as seen from above; Figure 6 is a cross-sectional view of a single unit of the apparatus of Figure 5; and Figure 7 is a cross-sectional view of a single unit of an alternative form.

The apparatus is shown in the form of a tear drop that fits under the calcaneus or heel * of the foot of the user. It is to be understood however, that the apparatus may take the form of any other shape, and may extend under a further portion of the foot or under the whole of the plantar surface or the entire underside of the foot. S... S..

Referring to Figures 1 and 2, there is shown an apparatus of the present invention generally indicated as 2. The apparatus comprises a member 4 having a major surface 6. In use, the apparatus 2 is disposed in an item of footwear (not shown for clarity) with the major surface 6 uppermost, so as to be contacted by the planar surface of the foot of the user, in this case the right foot. The apparatus 2 shown in Figures 1 and 2 is intended to be positioned beneath the heel portion of the foot of the user, that is beneath the calcaneus.

The apparatus 2 comprises a central cavity or hole 8. The cavity 8 may be left open, as shown in the figures, or may be filled with a material having a greater softness and lower resistance to impact than that of the member 4.

The apparatus 2 comprises a plurality of structures 10 for providing a variable resistance to impact from the foot of the user. The structures 10 are in the form of frusto.copjca1 units 12 extending upwards from the major surface 6 towards the foot of the user, when in use. As will be seen in Figures 2, 3 and 4, the units are of different heights and circumference, with the larger units being placed to counter the greatest impact from the foot of the user during use.

In use, the apparatus is incorporated into the sole of an item of footwear or inserted into the item, for example in the form of an insole. In the latter case, the apparatus shown in the figures may be encased in a soft material, such as a foam, gel or like, provided that the action of the apparatus, in particular the structures 10 is not reduced or compromised. When the foot of the user applies pressure to or impacts the structures 10, the units are compressed. Initially, under a low impact condition, such as walking or standing, the structure offers a low resistance to compression and is readily deformed. As the activity of the user increases, for example the user starts to * jog or run, the impact of the foot of the user against the structures 10 increases and *: .: acts to further compress the structures. However, as the structures are further compressed, their resistance to compression increases, providing a firm platform for the foot of the user and providing increased support.

Referring to Figure 5, there is shown a view of the apparatus of a second embodiment, generally indicated as 102. The apparatus comprises a member 104 having a major surface 106 and a central cavity 108 of the same general form as shown in Figures 1 to 4 and described above. Structures 1 10 comprising frusto-conical units 112 extend from the surface 106 towards the foot of the user, when in use. As shown in Figure 5, and in greater detail in Figure 6, the conical units 112 are each provided with a cylindrical bore 114 extending theretlirough. The diameter and depth of the bore 114 may be varied to alter the resistance of the individual units to impact and compression. In this way, the apparatus may be customised to fit a particular person and/or their activities.

Finally, referring to Figure 7, there is shown a alternative design of unit 212. In this case, the unit 212 is of a generally frusto-conica! form with a central bore 214.

However, the central bore is tapered in the longitudinal direction, such that the narrow end of the taper is innennost. The form and dimensions of the tapered bore may be varied in order to alter the compressibility of the unit and its resistance to impact by the foot of the user.

In use, the apparatus will be flexible enough so as to easily mould to the sole of the shoe of the subject, and also to the plantar surface of the subject's foot. The apparatus may come in different sizes in order to fit the foot of the subject, or it may be manufactured in a limited number of sizes, or even only one size, which can then by S.,.,. trimmed to fit the foot of the subject as desired. 5* *. . * * S.. * 20 * * *SS* 5. S a * * * *. l0

Claims

I. An apparatus for responding to the varying conditions of pressure in the foot of a subject comprising; a member having a surface for contacting the plantar surface of the foot of the subject; and the member comprising structures for absorbing and reacting to various pressures exerted by the foot of the subject whilst in use, the structures providing a first resistance to lower impact forces applied by the foot to the structures and a second resistance to higher impact forces applied by the foot to the structures.
2. An apparatus according to claim 1, wherein the structures are disposed on the surface of the member. S * 55.,
3. An apparatus according to claim 1 or 2, wherein the apparatus is comprised in the sole of an item of footwear to be worn by the subject.

S
4. An apparatus according to claim I or 2, wherein the apparatus is in a form to *. : be incorporated into an item of footwear. * S.
5. An apparatus according to claim 4, wherein the apparatus is an insole.
6. An apparatus according to any preceding claim, wherein the member is flexible.
7. An apparatus according to claim 6, wherein the member comprises polyurethane.
8 An apparatus according to claim 7, wherein the polyurethane is selected so as to provide a third resistance to impact.
9. An apparatus according to either of claims 7 or 8, wherein the polyurethane comprises one or more fillers.
10. An apparatus according to any preceding claim, wherein at least a portion of the member extends beneath the calcaneus bone of the foot of the subject.
11. An apparatus according to claim 10, wherein the portion of the member that underlies the calcaneus bone of the foot of the user when in use has a lower resistance to impact than the remaining portion of the member.
12. An apparatus according to claim 11, wherein the lower resistance to impact is provided by the said portion of the member comprising a material of lower : resistance to impact. ***. S...

:.**
13. An apparatus according to any preceding claim, wherein the structures for absorbing and reacting to various pressures from the foot whilst in use are * 20 disposed on the surface of the member so as to contact the areas of the plantar *.*** surface of the foot exposed to high pressures during a variety of activities. S. * * * * * S.
14. An apparatus according to any preceding claim, wherein each structure comprises a unit, the unit having a central longitudinal axis aligned with the direction of impact from the foot of the user when in use.
15. An apparatus according to any preceding claim, wherein each structure is compressible and compresses under the action of an impact from the foot of the user when in use.
16. An apparatus according to claim 15, wherein the resistance to compression of the unit increases as the unit is compressed.
17. An apparatus according to claim 16, wherein the increase in the resistance to compression increases progressively with increased compression.
18. An apparatus according any of claims 15 to 17, wherein the unit is tapered externally.
19. An apparatus according to claim 18, wherein the narrow end of the taper is towards the foot of the user, when in use.
20. An apparatus according to any of claims 15 to 19, wherein the unit comprises a cavity extending along the longitudinal axis of the unit.

S...
21. An apparatus according to claim 20, wherein the cavity extends along the *::::* entire length of the unit. *5
22. An apparatus according to either of claims 20 or 21, wherein the unit has an S..

* 20 internal taper, such that the wall thickness of the unit changes along the * longitudinal axis. *S** S. * * . * * S.
23. An apparatus according to claim 22, wherein the wall is thinner at the end towards the foot of the user when in use.
24. An apparatus according to either of claims 20 or 21, wherein the cavity is cylindrical.
25. An apparatus according to any of claims 14 to 24, wherein the unit is in the form of a pyramid, a cone, a frusto-cone, a dome, a cylinder or a combination thereof.
26. An apparatus according to any of claims 14 to 25, wherein buttresses extend between adjacent units.
27. An apparatus according to any of claims 14 to 25, wherein the structures have different heights.
28. An apparatus according to any of claims 14 to 27, wherein the strucutres have different circumferences..
29. An apparatus according to any preceding claim, wherein the structuress are of a material having a shore hardness greater than the shore hardness of the material of the member.
30. An apparatus according to claim 29, wherein the shore hardness of the material of the protrusions is in the range of from 50 to 120. *S.. *SI.

** **
31. An apparatus according to claim 30, wherein the shore hardness of the material of the protrusions is about 90. * 20
32. An apparatus according to any preceding claim, wherein the member is of a *. : material having a shore hardness of from 30 to 50. *
33. An apparatus according to claim 32, wherein the member is of a material having a shore hardness of about 40.
34. An apparatus according to any preceding claim, wherein some or all of the structures are arranged in a single line.
35. An apparatus according to any of claims 1 to 26, wherein some or all of the structures are arranged in a plurality of lines.
36. An apparatus according to any of claims I to 26, wherein some or all of the Structures are arranged randomly on the surface.
37. An apparatus according to any preceding claim, wherein the structures for absorbing and reacting to various pressures from the foot comprise protrusions extending from the surface of the member.
38. An apparatus for responding to the varying conditions of pressure in the foot of a subject substantially as hereinbefore described having reference to any of Figures 1, 2, 3, 4 or 5.
39. An item of footwear comprising an apparatus according to any preceding claim.

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