WO2015145329A1

WO2015145329A1 - Insert for postural control of the foot

Info

Publication number: WO2015145329A1
Application number: PCT/IB2015/052108
Authority: WO
Inventors: Camillo Buratto
Original assignee: Podarte Srl
Priority date: 2014-03-24
Filing date: 2015-03-23
Publication date: 2015-10-01
Also published as: ES2719434T3; EP3122198B1; EP3122198A1

Abstract

The present invention relates to an insert 10 for postural control of the foot, able to control both excessive pronation and excessive supination, ensure natural extension of the podalic helix and reduce overloading in the metatarsal zone. The insert 10 is designed to be arranged in a footwear article 5 comprising a sole portion A, a central portion B and a heel portion C. The insert 10 is made of a material which is more rigid than the material from which the footwear article 5 is made and is shaped in the form of an H and comprises a connecting portion 40 designed to be positioned in the central portion B from which two front arms 20 and two rear arms 30 extend in opposite directions. The invention relates, moreover, to a footwear article 5 comprising such an insert 10.

Description

"Insert for postural control of the foot"

The present invention relates to an insert for postural control of the foot. In particular, the present invention relates to an insert for postural control of the foot, intended to be inserted inside a footwear article, such as an insole, a midsole or an outsole.

The invention relates, moreover, to the footwear article comprising such an insert.

Inserts which are designed to be arranged inside an outsole or a midsole in order to correct postural defects of the foot during walking, such as excessive pronation or excessive supination, are known.

Also known are inserts designed to be arranged inside an outsole or a midsole so as to act as a rigid support for the sole of the foot and thus alleviate any pain caused by inflammation of the metatarsal zone or the heel zone of the feet.

These inserts, although widely used, are not without defects.

Owing to their structural rigidity, in fact, if on the one hand they allow the correction of any postural defects and may act as a support for the foot sole, on the other hand they interfere with the natural extension of the podalic helix, i.e. the movements which the foot performs during the various phases of the walking cycle.

Moreover, these inserts, by stiffening the sole in which they are provided, have the effect that the kinetic energy which is developed during the strike phase of the heel and the foot-sole in the walking or running movement is not subsequently transmitted back to the lower limbs, causing therefore a greater consumption of muscular energy.

In fact the inserts described above, while correcting any postural defects, block in fact the foot, not allowing it to move in a natural manner.

Constructional designs of such types of inserts are for example described in US 2012/0233877, which relates to an insert intended to block the midfoot of the user, as well as in DE 102010027418, US 2013/139412 and US 1907995.

This problem is accentuated even further in the case of old people in whom, owing to a natural articular rigidity, the foot loses per se propulsive force, making the walking movement even more tiresome.

The object of the present invention is therefore to overcome at least partially the drawbacks mentioned above in relation to the inserts for postural control of the known type.

A task of the present invention is to provide an insert for postural control of the foot which is able to correct any postural defects, optimizing and ensuring the natural extension of the podalic helix.

Moreover, a task of the present invention is to make available an insert for postural control of the foot which is able to transmit back to the lower limbs at least part of the kinetic energy which is developed during the walking or running movement.

Furthermore, a task of the present invention is to make available an insert for postural control of the foot which in a single configuration is able to correct both excessive supination and any pronation of the foot.

A further task of the present invention is to make available an insert for postural control of the foot which acts as a support for the foot, reducing at the same time the overloading underneath the metatarsal heads.

Moreover, a task of the present invention is to make available an insert for postural control of the foot which may be inserted inside midsoles or outsoles made of soft and flexible material, ensuring, in addition to a correct posture, adequate supporting of the foot.

Finally, a task of the present invention is to make available a footwear article provided with such a postural control insert.

The aforementioned object and tasks are achieved by an insert for postural control of the foot according to Claim 1 and by a footwear article according to Claim 12.

In order to illustrate more clearly the innovative principles of the present invention and its advantages compared to the prior art, an example of embodiment applying these principles will be described below with the aid of the attached drawings. In the drawings:

- Figure 1 shows an exploded perspective view of a footwear article comprising the insert according to the present invention;

- Figure 1A shows a bottom view of a footwear article comprising the insert according to the present invention;

- Figure 2 shows a top plan view of a first embodiment of the insert according to the invention;

- Figure 3 shows a side view of the insert according to Figure 2;

- Figure 4 shows a view, similar to that of Figure 2, but relating to a second embodiment of the insert according to the invention;

- Figure 5 shows a perspective view of the insert according to Figure 4;

- Figure 6 shows a cross-sectional view along the line VI -VI of Figure 4;

- Figure 7 shows a cross-sectional view along the line VII- VII of Figure 4;

- Figure 8 shows a cross-sectional view along the line VIII-VIII of Figure 4;

- Figure 9 shows a top plan view of a third embodiment of the insert according to the invention;

- Figure 10 shows a side view of the insert according to Figure 9;

- Figure 11 shows a view, similar to that of Figure 9, but relating to a fourth embodiment of the insert according to the invention;

- Figure 11A shows a schematic view, on a larger scale, of the detail indicated by the letter W in Figure 11 ;

- Figure 12 shows a perspective view of the insert according to Figure 11;

- Figure 13 shows a cross-sectional view along the line XIII-XIII of Figure 11;

- Figure 14 shows a cross-sectional view along the line XIV -XIV of Figure 11;

- Figure 15 shows a top plan view of a fifth embodiment of the insert according to the invention;

- Figure 16 shows a view, similar to that of Figure 15, but relating to a sixth embodiment of the insert according to the invention;

- Figure 17 shows a cross-sectional view along the line XVII-XVII of Figure 16;

- Figure 18 shows a top plan view of a seventh embodiment of the insert according to the invention;

- Figure 19 shows a view, similar to that of Figure 18, but relating to an eighth embodiment of the insert according to the invention;

- Figures 20-20F show in schematic form the insert according to the invention in different operative configurations.

The present invention relates to an insert for postural control of the foot 10 designed to be arranged inside a footwear article 5. The footwear article is understood as being for example an insole, a midsole or a sole of any type, both for the sporting use and for walking.

The description of the insert 10 and its single components provided below relates to a footwear article 5 which is used correctly. In particular, "front" will be used to identify the part of the insert, or its single components, which is/are relatively closer to the toe of the foot, while "rear" will be used to indicate the part of the insert, or its single components, which is/are relatively closer to the heel. Similarly, "top" will refer to the part of the insert, or its single components, which is/are relatively more distant from the ground, while "bottom" will be used to indicate the part of the insert, or its single components, which is/are relatively closer to the ground. The terms "medial" and "lateral" will be understood, in a known manner, as being relative to a hypothetical sagittal plane of the user of the insert, i.e. relative to the plane which runs from the head to the feet of the user, and in particular "medial" will be used to refer to the part of the insert closest to the sagittal plane and "lateral" will be used to refer to the part of the insert furthest from the sagittal plane.

Below, for easier illustration, the footwear article 5 will be identified, albeit in a not exclusive manner, with a midsole. This midsole 5 is designed to be joined to a tread 6, so as to obtain a complete outsole 7 (see Figure 1).

The midsole 5, inside which the insert 10 may be arranged, comprises a sole portion A, a central portion B and a heel portion C. The sole portion A of the midsole 5 is the portion on which the forefoot rests, the central portion B of the midsole 5 is the portion on which the midfoot rests and the heel portion C of the midsole 5 is the portion on which the hindfoot rests.

The insert 10 is made of a material which is more rigid than the material from which the midsole 5 is made. Preferably, the insert 10 is made of polymer material, such as aliphatic polyamides (nylon) and aromatic polyamides (kevlar). Alternatively, the insert 10 may be made of a composite material, such as carbon fibre or glass fibre.

The insert may be as a whole semi-rigid, although, owing to its particular form, as will become clear from the description below, it will have in any case a certain degree of elasticity so that it can adapt perfectly to the movements of the foot and transmit back at least part of the energy stored inside it during the various phases of the walking movement.

On the basis of the above, the insert 10 is therefore advantageously designed to be inserted inside outsoles 7 or midsoles 5 which are made of flexible material and characterized by a low specific weight such as expanded EVA or expanded polyurethane.

With reference to the attached figures, the insert 10 is shaped in the form of an H and comprises a connecting portion 40 which is designed to be positioned in the central portion B of the midsole 5 and from which two front arms 20 and two rear arms 30 extend in opposite directions to each other (see Figures 1 and 1A). The connecting portion 40 forms a narrow zone of the insert 10 and defines an axis of articulation T about which the two front arms 20 and the two rear arms 30 may flex, during the walking cycle, independently of each other.

In other words, as will become clear from the description below, the portion 40 of the insert 10, on the one hand, acts as a connection between the two front arms 20 and the two rear arms 30 and, on the other hand, acts as an articulation between them, allowing during use of the insert 10 controlled flexing of the arms 20, 30 about its axis of articulation T (see for example Figures 20-20 F).

As can be clearly seen in the attached figures, the axis of articulation T is arranged perpendicularly with respect to the longitudinal axis L of the insert.

In accordance with the invention, the two front arms 20 extend, from the connecting portion 40, along a medial peripheral part AM and a lateral peripheral part AL of the sole portion A of the midsole 5, respectively (see Figure 1A).

In the attached figures, the front arm which extends along the medial peripheral part AM is indicated by the reference number 22, while the front arm which extends along the lateral peripheral part AL is indicated by the reference number 24.

In turn, the two rear arms 30 extend, from the connecting portion 40, along a medial peripheral part CM and a lateral peripheral part CL of the heel portion C of the midsole 5 respectively (see Figure 1A).

In attached figures, the rear arm which extends along the medial peripheral part CM is indicated by the reference number 32, while the rear arm which extends along the lateral peripheral part CL is indicated by the reference number 34.

In accordance with the invention, as can be clearly seen in Figures 3, 8, 10, 14 and 17, the two rear arms 30 have a thickness, calculated along a reference axis Z perpendicular to the longitudinal plane XY of the insert 10, greater than the thickness of the connecting portion 40 and the thickness of the two front arms 20. In this way, the two rear arms 30 act as a support and reinforcement for the heel portion C of the midsole 5.

In particular, as will become clear from the description below, this configuration of the two rear arms 30 ensures that the midsole 5, made of a material less rigid than that of the material from which the insert 10 is made, does not collapse in the heel potion C, even if it is used for a long time and/or by overweight persons. The two rear arms 30 may in practice be regarded as stiffening ribs inserted inside the flexible material from which the midsole is made. In this way, it is possible to use for the midsole also expanded and light material, increasing the comfort of the user and ensuring at the same time, as will become clear below, the postural control of the foot.

Preferably, as shown in Figure 1, the insert 10 is applied to the bottom surface of the midsole 5. In this case, the medial peripheral parts AM, CM and the lateral peripheral parts AL, CL of the sole portion A and the heel portion C of the midsole 5 are the portions of the midsole 5 arranged respectively in the vicinity of the bottom perimeter of the midsole 5.

In the case where the midsole 5 has side walls which are flared downwards, the front arms 22, 24 and the rear arms 32, 34 of the insert 10 will be arranged in a position slightly more inwards than if the side walls of the midsole 5 are substantially straight/vertical. As will be explained in detail below, the insert 10, in fact, in order to perform better its function, is preferably positioned in an area which corresponds substantially to the projection, on the bottom surface of the midsole 5, of the profile of the user's foot.

In fact, as can be seen in the attached figures, the two front arms 22, 24 and the two rear arms 32, 34 are shaped, with reference to the longitudinal plane XY, with a profile which follows the anatomy of the foot.

In the embodiment shown in Figures 2 and 3, the two front arms 22, 24 of the insert 10 have substantially the same length and are shaped to follow the anatomy of the 1st metatarsal bone and the 5th metatarsal bone of the user's foot. In such an embodiment, advantageously the two front arms 22, 24 support the 1st and 5th metatarsal bones of the user's foot during extension of the podalic helix of the foot and terminate preferably before the corresponding metatarsal heads. Similarly, the two rear arms 32, 34 have substantially the same length and are shaped to follow the medial profile and the lateral profile of the user's heel.

In the embodiment shown in Figure 15, the front arm 22 is shaped to follow the anatomy of the 1st metatarsal bone of the user's foot and terminates preferably in the sole portion of the midsole 5 on which the head of the 1st metatarsal bone and/or the corresponding proximal phalange of the user's foot is/are intended to rest.

With reference still to the embodiment shown in Figure 15, the front arm 24 is shaped to follow the anatomy of the 5th metatarsal bone of the user's foot and terminates in the sole portion A of the midsole 5 on which the head of the 5th metatarsal bone and/or the corresponding proximal phalange of the user's foot is/are intended to rest.

With reference still to the embodiment shown in Figure 15, the two rear arms 32, 34 have substantially the same length and are shaped to follow the medial profile and the lateral profile of the heel of the foot and terminate in the heel portion C of the midsole 5, embracing and supporting the medial and lateral edge of the heel of the user's foot.

In the embodiment shown in Figure 18, the front arm 22 is shaped to follow the profile of the 1st metatarsal bone of the user's foot and terminates in the sole portion A on which the corresponding medial proximal phalange is intended to rest. In this way it is possible to support and correct forefeet which are affected by supination or by pathological forms, such as hallux valgus.

With reference still to the embodiment shown in Figure 18, the front arm 24 is shaped to follow the profile of the 5th metatarsal bone of the user's foot and terminates in the sole portion A of the midsole 5 on which generally the central portion the 5th metatarsal bone of the user's foot is intended to rest. It should be noted, however, that the portion of the foot resting on the front arm 24 may vary depending on the form of the user's foot. Moreover, small variations in length of the front arm 24, with respect to that shown in schematic form in Figure 18, may be possible depending on the intended corrections which are to be obtained with the footwear article 5 by means of provision of the insert 10.

With reference still to the embodiment shown in Figure 18, the rear arm 32 is shaped to follow the medial profile of the heel of the foot and terminates in the heel portion C of the midsole 5 on which the rear end of the heel of the user's foot is intended to rest. In this way, the rear arm 32 provides a greater support for feet affected by excessive pronation, heel valgus or flat-foot condition.

With reference still to the embodiment shown in Figure 18, the rear arm 34 is shaped so as to embrace and support the lateral edge of the foot heel and terminates in the heel portion C in front of the zone on which the calcaneal tuberosity is intended to rest.

Alternatively, in an embodiment not shown in the attached figures, the two rear arms 32 and 34 may be arranged symmetrically about the longitudinal axis L, compared to the configuration shown in Figure 18.

With specific reference to the two rear arms 30, the embodiment shown in Figure 18 is particularly advantageous for control of excessive heel pronation. Moreover, this embodiment assists postural control of the user's foot during the first phase of the walking step, where heel strike occurs.

Still with specific reference to the two rear arms 30, the embodiment shown in Figure 2, that in which the two rear arms 30 have substantially the same length, allows a neutral supporting action during the heel strike phase.

The configuration of the two rear arms 30 symmetrical with respect to that shown in Fig.

18, in turn, favours in a symmetrical manner greater control of excessive heel supination during the heel strike phase.

From the above description it is clear how the rear arms 32, 34 are specifically designed to act effectively already during the initial heel strike phase, controlling excessive pronation and supination of the user's foot.

In the embodiments shown, the connecting portion 40 is arranged, as already mentioned, in the central portion B of the midsole 5 and is arranged along a direction T substantially perpendicular to the longitudinal axis L of the midsole 5 (see Figure 1A).

The function of the connecting portion 40, which defines the axis of articulation T, is to act as an articulation between the two front arms 20 and the two rear arms 30, allowing said front arms and rear arms to perform controlled flexing movements about the axis of articulation T.

The provision of the connecting portion 40 essentially allows, even if the insert 10 is made of semi-rigid material, an insert 10 to be obtained which overall is able to adapt to the anatomy of the user's foot and assist its movements.

Obviously, different shapes and profiles are possible for the two front arms 22, 24, for the two rear arms 32, 34 and for the connecting portion 40 in order to satisfy specific requirements.

Preferably, in accordance with the embodiments shown, the insert 10 is suitably shaped along its longitudinal axis L so as to adapt better to the anatomy of the foot.

In detail, as can be clearly seen in Figures 3, 8, 10, 14 and 17, the thickness of the two front arms 22, 24, calculated along the reference axis Z, perpendicular to the longitudinal axis L, is smaller than the thickness of the connecting portion 40 and the thickness of the two rear arms 32, 34.

By way of a non-limiting example, in the preferred embodiment, the thickness of the two rear arms 32, 34 is equal to about 8-9 mm, while the thickness of the connecting portion 40 is equal to about 6-7 mm. Obviously, the thicknesses will be connected in the zones where the rear arms 32, 34 engage in the connecting portion 40.

The thicknesses of the two front arms 22, 24, of the two rear arms 32, 34 and of the connecting portion 40 are specifically designed to prevent collapse of the midsole or the outsole in which the insert 10 is inserted in cases of overweight or excessive pronation.

Advantageously, as shown in the attached figures, the thickness of the two front arms 22, 24 calculated along the reference axis Z is not constant. The thickness of the front arms 22, 24 decreases from the connecting portion 40 towards the terminal ends of the two arms.

Preferably, the thickness of the two front arms 22, 24 decreases in the proximity of the front ends down to a value of 2-3 mm.

The thicknesses of the two front arms 22, 24 will also be connected in the zones where they engage in the connecting portion 40.

The profile of the insert 10, in fact, considered as a whole, does not have points of discontinuity.

As mentioned, the connecting portion 40 forms a narrow zone of the insert 10. Preferably, the connecting portion 40 has, in fact, a width, measured along a direction parallel to the axis T, equal to about 40-60% of the maximum width of the rear portion of the insert 10, i.e. the portion occupied by the rear arms 32, 34.

In a similar manner, the connecting portion has preferably a width equal to about 30-50% of the maximum width of the front portion of the insert 10, i.e. the portion occupied by the front arms 22, 24.

By way of example, the connecting portion has preferably a width of about 3-4 cm. Preferably, the maximum width of the rear portion of the insert measures about 6-7 cm, while the maximum width of the front portion measures preferably about 8-9 cm.

As can be clearly seen in Figures 3 and 10, in accordance with the invention, each front arm 22, 24 is shaped along the entire length with a continuous concave profile, having the concavity directed upwards. As can be clearly seen in the attached figures, the front end of the arms 22, 24 is raised with respect to the plane of contact XY of the insert. In detail, in Figures 3 and 10 it can be seen how the front end 25 of the arm 24 is raised with respect to the plane of contact XY of the insert 10. In this way, the front portion of the insert 10 may assume a curved (or rocker) configuration designed to facilitate the natural extension of the podalic helix of the foot.

With reference still to Figures 3 and 10, the two rear arms 30 have a non-uniform thickness. Said thickness gradually increases along the longitudinal axis L of the insert 10 starting from the rear end of each arm 32, 34 and gradually decreases in the proximity of the connecting portion 40. In this way better supporting and reinforcing of the heel of the user's foot are ensured.

With reference to the embodiments shown in Figures 4, 11, 16 and 19, the front arms 22, 24, the rear arms 32, 34 and the connecting portion 40 may have weight-reducing cavities 51 on their top surface.

These cavities 51 have the function of further lightening the insert 10, without however adversely affecting its mechanical properties. In fact, as can be clearly seen in the attached drawings, the cavities 51 are defined by ribs 52 arranged along a direction substantially perpendicular to the longitudinal axis L of the insert 10. In this way, as will be clear from the description which follows, the front arms 22, 24 and the rear arms 32, 34 have a greater degree of flexibility compared to the configuration without cavities, allowing the insert 10 to better assist the movements of the foot.

Moreover, in the case where the insert 10 is embedded in the material which forms the midsole 5, for example by pre-loading it inside the mould used to produce the midsole 5, the provision of these cavities 51 will ensure a firm connection between insert 10 and midsole 5.

Advantageously, as shown in Figures 6-8, 13-14 and 17, the bottom surface of the front arms 22, 24 and the rear arms 32, 34 may be provided with weight-reducing zones 53. These weight-reducing zones 53 on the one hand allow further lightening of the insert 10 and on the other hand form seats suitable for receiving corresponding reliefs (not shown in the attached figures) provided on the top surface of the tread 6. In this way, as will be clear to a person skilled in the art, mounting of the tread 6 on the midsole 5 will be facilitated and at the same time will be more precise.

With reference to the embodiments shown in Figures 9-14, the two front arms 22, 24 and the two rear arms 32, 34 may be connected together respectively by a front support portion 26 and by a rear support portion 36. The function of these support portions is to ensure uniformity of the movements of the front arms and rear arms about the axis of articulation T of the connecting/ articulating portion 40, preventing for example any impacts with the ground or foreign bodies from causing excessive undesirable flexing of one or more arms about the axis of articulation T of the connecting/articulating portion 40.

As can be clearly seen in the attached figures, the front support portion 26 and the rear support portion 36 preferably have a thickness which is smaller than the thickness of the front arms 22, 24 and the thickness of the rear arms 32, 34. Preferably, as shown by way of example in Figure 11 A, said support portions 26, 36 have a reticular structure which allows them to act as elements for stabilizing the arms of the insert, without excessively increasing the weight of the latter.

Preferably, the front support portion 26 and the rear support portion 36 are arranged along the bottom surface of the insert 10.

Advantageously, in accordance with that shown in the attached figures, the front support portion 26 extends along the sole portion A of the intersole 5 on which the metatarsi of the user's foot are intended to rest and the rear support portion 36 extends along the heel portion C of the midsole 5 on which the heel of the user's foot is intended to rest.

As mentioned above, the insert 10 may be provided in the midsole 5 so as to be embedded in the material forming the midsole 5. Alternatively the midsole 5 may have along its bottom surface a corresponding receiving seat 9 for the insert 10. This insert may be fixed inside this seat 9 in a known manner, by means of a suitable bonding process.

The midsole 5 may be then fixed to a tread 6 so as to form a complete outsole 7 (see Figure 1).

In the case where the footwear article 5 is a sole and if the insert is not embedded inside the sole, the insert may be inserted inside the sole 5 by providing a suitable seat in the top surface of the sole 5.

Below, functioning of the insert 10 according to the invention is briefly described, with reference to the phases into which the walking cycle may be broken down and the embodiment of the insert 10 shown in Figures 16 and 17.

The comments made below are also applicable to the other embodiments shown.

In a manner known per se, the duration of the walking or ambulation cycle is defined as being between two successive contact instants of the heel of the same foot and is formed by a so- called "stance phase", which forms about 60% of the entire cycle, and a swinging phase, which corresponds to about 40% of the entire cycle.

The stance phase comprises:

- a heel strike phase, where the heel of the foot comes into contact with the walking surface;

- a total contact phase, where the entire foot-sole area is contact with the walking surface;

- a toe contact phase, where the heel of the foot is raised from the ground.

The swinging phase occurs instead between lifting of the toes of the foot from the ground and the subsequent heel strike of the same foot.

With reference to Figures 20A-20F, at the same time as the aforementioned phases, functioning of the insert 10 may be broken down into the following phases:

- take-up;

- full contact;

- propulsion;

- release

The take-up phase of the insert 10 occurs during the heel contact phase when the heel, after initially touching the walking surface with its outer part, rotates inwards in order to reduce the force of impact with the ground.

During the take-up phase, firstly the rear arm 34 arranged along the lateral peripheral part

CL of the heel portion C of the midsole 5 and then the rear arm 32 arranged along the medial peripheral portion CM of the heel portion C of the midsole 5 flex slightly with respect to the axis of articulation T of the connecting portion 40 (see Figures 20A and 20B). In Figures 20A and 20B, and in the following figures, the flexing movements of the front arms 22, 24 and the rear arms 32, 34 about the axis of articulation T are shown with respect to their rest configuration which is shown in broken lines.

The specific configuration of the two rear arms 32, 34 is such that they may respond to the stresses acting on them, indicated schematically by the arrows Fl and F2, independently of each other. Therefore, the two rear arms 32, 34 are able to cushion better the weight of the body and at the same time allow the foot to relax, adapting to the walking surface.

Moreover, the two rear arms 32, 34, flexing with respect to the axis of articulation T of the connecting portion 40, are able to store the potential energy inside the insert 10, which will be advantageously released during the following phases.

The full contact phase of the insert 10 occurs during the total contact phase of the foot when its sole portion, after initially touching the walking surface with its outer part, rotates inwards so as to make full contact with the walking surface.

During the full contact phase, firstly the front arm 24 arranged along the lateral peripheral part AL of the sole portion A of the midsole 5 and then the front arm 22 arranged along the medial peripheral portion AM of the sole portion A of the midsole 5 flex slightly with respect to the axis of articulation T of the connecting portion 40 (see Figures 20C and 20D).

In a similar manner to that described above with reference to the two rear arms 32, 34, the specific configuration of the front arms 22, 24 is such that they may respond to the stresses acting on them, indicated by the arrows F3 and F4, independently of each other. Therefore, the two front arms 22, 24 are also able to cushion better the weight of the body and at the same time allow the foot to adapt to the walking surface.

In this case also, flexing of the two front arms 22, 24 has the effect that the potential energy is stored inside the insert 10.

The propulsion step of the insert 10 occurs during the toe contact phase of the foot when the heel of the foot lifts from the walking surface and the toes of the foot flex dorsally.

During the propulsion phase, the heel no longer bears on the two rear arms 32, 34 which recover their original position with respect to the axis of articulation T of the connecting portion 40 (see Figure 20E). In this way, the two rear arms 32, 34 are able to release in the form of kinetic energy the potential energy stored during the take-up phase. This kinetic energy is converted substantially into a thrust - schematically indicated by the arrows SI - acting on the heel of the foot, facilitating the forwards movement. The foot is prepared for the following walking phase, stressing less the leg muscles and the knee joint.

The release phase of the insert 10 occurs during the swinging phase of the foot, when the toes of the foot are raised from the walking surface.

During the swinging phase, the sole of the user's foot no longer bears on the two front arms 22, 24 of the insert 10. These arms may therefore recover their original position with respect to the axis of articulation T of the connecting portion 40 and release, in the form of kinetic energy, the potential energy stored during the contact phase (see Figure 20F).

This kinetic energy is converted into a thrust - schematically indicated by the arrows S2 - acting on the sole of the foot so as to project it forwards.

At the end of the release step, the insert 10 again assumes its original configuration shown schematically in Figure 20.

From the above it is clear how the insert 10 optimizes and assists extension of the podalic helix of the foot. The arms of the insert 10, in fact, being able to flex independently of each other with respect to the axis of articulation T allow the insert to be adapted to the movements of the foot.

Moreover, the insert 10 is able to control any excessive pronation of the foot.

In the case where the foot, both during the heel contact phase and during the full contact phase, continues to pronate after impact with the ground towards the inside, the rear arm 32, which is arranged in the proximity of the medial peripheral part of the heel portion C, and the front arm 22, which is arranged in the proximity of the medial peripheral part of the sole portion A, will oppose this movement.

The thicknesses of the two arms 22, 32 are in fact fixed so that flexing of said arms with respect to the axis of articulation T of the connecting portion 40 cannot exceed a given physiological value.

In this way, therefore, the two arms 22, 32, once a maximum flexing value is reached, will oppose any excessive pronation of the foot, allowing it to remain in a correct posture.

Advantageously, the insert 10 is able to control, with a single configuration, also any excessive supination of the foot.

The insert 10 also operates advantageously in the case of insufficiency of the first ray due to various causes (hallux vagus, rigid toe, etc.); in fact the front arm 22 and the front arm 24, elongated in their specific positions respectively underneath the 1st metatarsal bone and the first proximal phalange and the 5th metatarsal bone and the fifth proximal phalange, support with a wedge effect the first toe and the lateral part of the foot. In this way, said front arms 20, during the propulsion phase, help to rebalance the pressure and the force imparted to the five metatarsi, during the course of the dorsifiexion movement of the foot. The semi-rigid configuration of the front arms 20 and rear arms 30 of the insert 10 and the provision of the connecting portion 40, which acts as an articulation between the arms, helps natural extension of the podalic helix which is normally defective in the case of supinated feet.

It should be emphasized that the support portions 26, 36, owing to their small thicknesses and the possible reticular structure, interfere to a minimum degree with the movements of the two front and rear arms, which continue to able to respond independently of each other to the stresses acting on them.

Moreover, the insert 10 advantageously may be inserted in midsoles or soles which have extremely low hardness values, for example 40-45 Shore A, without running the risk of these midsoles or soles collapsing under the weight of the user. On the basis of that described above, in fact, the insert 10 is able to stiffen the midsole to which it is applied, without however interfering with the movements of the foot.

The insert 10 may be regarded as being an advantageous rigid lever which allows a uniform transfer, or smooth transition, of the load from the take-up phase to the release phase. It should also be noted how in a normal shoe, without the insert, during the thrust phase of the foot, the zones situated at the bottom (underneath) the metatarsal heads, which are therefore clearly the most exposed to stress, are particularly stressed. The structure which is semi-rigid, but which at the same time has a certain elasticity of the insert, allows transfer of the load in a gradual manner between hindfoot, midfoot, forefoot and phalanges, reducing the pressure peaks underneath the heads of the metatarsi and facilitating extension of the podalic helix. The soles/footwear with insert 10 are therefore recommended for all persons suffering from articular rigidity, arthritis, arthrosis and diabetic foot syndrome.

Moreover, the insert 10 ensures natural extension of the podalic helix of the foot, facilitating and accompanying it.

Obviously the description above of an embodiment applying the innovative principles of the present invention is provided by way of example of these innovative principles and must therefore not be regarded as limiting the scope of the rights claimed herein. For example, the characteristic features of the various solutions shown here may be combined with each other according to specific needs and wishes. For example, the support portions 26 and 36 may also be provided in the other embodiments shown, as may be easily imagined by the person skilled in the art. Similarly it is possible to design inserts 10 which have a mirror-image configuration about the longitudinal axis L, compared to that shown in the figures.

Finally, exact forms and proportions of the various parts may vary depending on the specific practical requirements.

Claims

1. Insert (10) for postural control of the foot, designed to be arranged in a footwear article (5) comprising a sole portion (A), a central portion (B) and a heel portion (C), said insert (10) being made of a material which is more rigid than the material from which the footwear article (5) is made and being shaped in the form of an H, comprising a connecting portion (40) which is designed to be positioned in the said central portion (B) and from which two front arms (20; 22, 24) and two rear arms (30; 32, 34) extend in opposite directions to each other, wherein the connecting portion (40) forms a narrow zone of the insert (10), defining an axis of articulation (T);

the two front arms (20; 22, 34) extend, from the connecting portion (40), along a medial peripheral part (AM) and a lateral peripheral part (AL) of the sole portion (A) of the footwear article (5), respectively;

the two rear arms (30) extend, from the connecting portion (40), along a medial peripheral part (CM) and a lateral peripheral part (CL) of the heel portion (C) of the footwear article (5), respectively;

the two rear arms (30) having a thickness, calculated along a reference axis (Z) perpendicular to a longitudinal plane (XY) of the insert (10), greater than the thickness of the connecting portion (40) and the thickness of the two front arms (20; 22, 24), said rear arms (30; 32, 34) acting as a support and reinforcement for the heel portion (C) of the footwear article (5), preventing collapse thereof and being designed to prevent excessive pronation of the foot;

the insert (10) being characterized in that the two front arms (20; 22, 24) and the two rear arms (30; 32, 34) are designed to flex independently of each other relative to the axis of articulation (T) of the connecting portion (40) and in that

each front arm (22, 24) is shaped, along the entire length, with a continuous concave profile, having its concavity directed upwards, designed to accompany the physiological execution of the step.

2. Insert (10) according to Claim 1, characterized in that each rear arm (32, 34) has a nonuniform thickness, said thickness gradually increasing along the longitudinal axis (L) of the insert (10) from the rear end of each rear arm (32, 34) and gradually decreasing in the proximity of the connecting portion (40) .

3. Insert (10) according to Claim 1, characterized in that the front arm (22), which extends along the medial peripheral part (AM) of the sole portion (A) of the footwear article (5), is shaped to follow the anatomy of the 1st metatarsal bone of the user's foot and terminates in the sole portion (A) of the footwear article (5) on which the head of the 1st metatarsal bone and/or the corresponding proximal phalange of the user's foot is/are intended to rest.

4. Insert (10) according to Claim 1, characterized in that the front arm (24), which extends along the lateral peripheral part (AL) of the sole portion (A) of the footwear article (5), is shaped to follow the anatomy of the 5th metatarsal bone of the user's foot and terminates in the sole portion (A) of the footwear article (5) on which the head of the 5th metatarsal bone and/ or the corresponding proximal phalange of the user's foot is/are intended to rest.

5. Insert (10) according to Claim 1, characterized in that the first rear arm (32) is shaped to follow the medial profile of the heel of the foot and in that the second rear arm (34) is shaped to follow the lateral profile of the heel of the foot; said rear arms (32, 34) terminating in the heel portion (C) of the footwear article (5) so as to embrace and support the medial and lateral edge of the heel of the user's foot.

6. Insert (10) according to Claim 1, characterized in that the rear arms (32, 34), the front arms (22, 24) and the connecting portion (40) have weight-reducing cavities (51) on their top surface.

7. Insert (10) according to Claim 1, characterized in that thickness of each front arm (22, 24) is not uniform, said thickness gradually decreasing along the longitudinal axis (L) of the insert (10) from the connecting portion (40) towards the front end of each front arm (22, 24).

8. Insert (10) according to Claim 1, characterized in that the two front arms (22, 24) and the two rear arms (32, 34) are connected together by a front support portion (26) and a rear support portion (36), respectively.

9. Insert (10) according to Claim 8, characterized in that the front support portion (26) and the rear support portion (36) have a thickness smaller than the thickness of each front arm

(22, 24) and of each rear arm (32, 34); said front and rear support portions (26, 36) having a reticular structure.

10. Insert (10) according to Claim 8, characterized in that the front support portion (26) extends along the sole portion (A) of the footwear article (5) on which the metatarsi of the user's foot are intended to rest and in that the rear support portion (36) extends along the heel portion (C) of the footwear article (5) on which the heel of the user's foot is intended to rest.

11. Insert (10) according to Claim 1, characterized in that the insert (10) is made of semirigid material, said insert (10) being made of polymer material or composite material.

12. Footwear article (5) comprising a postural control insert (10) according to any one of the preceding claims, characterized in that the footwear article (5) comprises a corresponding receiving seat (9) for the postural control insert (10).

13. Footwear article (5) comprising a postural control insert (10) according to any one of claims 1-11, characterized in that the postural control insert (10) is embedded in the material forming the footwear article (5) .

14. Footwear article (5) according to Claim 12 or 13, said footwear article (5) consisting of a midsole (5) intended to be joined to a tread (6) so as to form an outsole (7), said midsole (5) being characterized in that it comprises a postural control insert (10) according to any one Claims 1-11.