EP0495023B1 - Multi-purpose footwear having a deformable talocalcanean section - Google Patents

Abstract

Items of footwear are described, in particular a multi-purpose shoe comprising in a mutually mobile arrangement a calcanean shell (17) and a leg (22) for supporting the ankle, via a deformable talocalcanean section (21) which at least partially surrounds the foot around the talocalcanean joint in order to at least partially accommodate the eversion and inversion movements of the ankle. Applications: sports or rehabilitation footwear.

Description

TECHNICAL AREA :

The present invention relates to the general technical field of footwear and relates, more particularly, to the technical field of shoes enveloping the foot, the heel and at least part of the ankle.

More particularly, but not exclusively, the invention relates to a multi-purpose shoe with a sporting character or even, again, usable as a simple walking shoe or even as a rehabilitation shoe.

The application examples cited above have only been listed for information and cannot be considered as limiting the scope of the object of the invention which applies to any shoe capable of supporting and support the joints of the foot and ankle of a human being, regardless of the type of movement and the type of activity involved.

A shoe, whatever the application considered, must assume different functions and, in particular, mechanical protection, thermal insulation, comfort of use and support or support for the joints of the foot and ankle. The specific use for which the shoe is intended leads to favoring one or more functions over others by playing, for example, on the nature and properties of the materials used or by providing or modifying zones and thicknesses of particular reinforcements or , again, by modifying the very shape of the shoe. Up to now, the contradiction existing between the need to protect and support the ankle and foot joints, on the one hand, and, at the same time, not to limit, or even disturb too strongly the foot joints and the ankle, on the other hand, has not been fully resolved.

The technical constraints involved are, in effect, contradictory, since any attempt to stiffen the the shoe's wrap-around structure improves joint support, to the detriment of user comfort. Conversely, improving the comfort of the user requires an increase in the flexibility of the enveloping structure of the shoe to the detriment of the support functions of the joints. In both cases, moreover, we deviate significantly from the optimal and natural conditions of the kinematics of the joints of the foot and ankle.

The absence or excess of compression can therefore also be the cause of torsion accidents of the foot and ankle joints, which are extremely frequent in sports where the joints are stressed in a particularly dynamic manner.

PRIOR TECHNIQUE :

A first type of sports shoes currently known consists of shoes enveloping simply the kick and the heel, that is to say that they simply ensure the flexible compression of a fraction of the calcaneus-pedous block. The use of such shoes is generalized to many sporting activities, such as tennis, football, athletics or jogging and the improvements relate, essentially, to the problems of damping of dynamic shocks, support of the arch of the foot or, on grip issues.

This type of shoe, by its very design, is not intended to ensure compression of the joints of the foot and, a fortiori, the ankle and no particular research has been carried out in this field.

A second type of sports shoe is constituted by sports shoes, said to be high, that is to say comprising not only a pedal shell, but also a flexible rod or envelope ensuring the containment of all the joints of the foot and ankle.

Shoes made according to this classic principle are used in most sports, such as basketball, football, tennis for example, and the support and compression provided being flexible, such shoes do not effectively protect the ankle joint in the event of torsion during the practice of a sporting activity. Because of the flexibility of the compression, the ankle joint is, in fact, not sufficiently supported in the event of unexpected twisting, which leads to the distension of the subtalar ligaments then, possibly, tibio-tarsal.

In the case of walking shoes and, more particularly, those intended for the practice of high mountains, the compression of the ankle joints is ensured in an almost rigid manner and, 'if it can be considered that torsional accidents, like sprains of the ankle, are, in most cases avoided, it should be considered that the comfort of use is reduced and that the ligament lesions occur then, not at the level of the ankle joints, but at the level knee.

US-A-4,563,825 (cf. the preamble to claim 1) also proposed a multi-purpose sports shoe, in particular for motorcyclists or skiers, having the advantage of ensuring correct ventilation of the foot, while by being flexible enough to allow easy walking. Such a shoe comprises a plantar shell adapted to provide support and reinforcement for the plantar mass of the foot and the calcaneus-pedious block. The shoe also includes a upper formed from a front part mounted directly on the shell by means of a double locking system with eyelets and hooks, and a rear part mounted articulated on the shell at the user's malleolus.

PRESENTATION OF THE INVENTION :

The object of the present invention therefore aims to propose a multi-purpose shoe which does not have the drawbacks of traditional shoes and which is capable of supporting the natural joints of the foot and ankle, without adversely affecting the comfort of use, while respecting the natural physiological movements of the foot and ankle joints.

Another object of the invention is to provide a multi-purpose shoe, of simple design and varied applications and accommodating all sporting practices.

A complementary object of the invention aims to propose a multi-purpose shoe capable of ensuring, simultaneously, the protection of the subtalar and tibio-tarsal joints.

• une coque plantaire constituée, notamment, d'une coque calcanéenne et adaptée pour assurer le soutien et le renfort de la masse plantaire du pied et du bloc calcanéo-pédieux,
• et une tige reliée à la coque par l'intermédiaire d'un dispositif autorisant un débattement relatif entre la tige et la coque, caractérisée en ce que :
  • . la tige est adaptée pour soutenir la masse du pied incluant une partie de l'astragale et au moins une partie de la masse postérieure du pied,
  • . et en ce que le dispositif est constitué d'une section sous-astragalienne présentant une rigidité inférieure à celles de la tige et de la coque calcanéenne, afin que la tige et la coque soient mobiles relativement, la section sous-astragalienne étant montée entre la tige et la coque calcanéenne en enveloppant, au moins partiellement, le pied au niveau d'un cône de révolution dénommé cône sous-astragalien et représentatif des mouvements d'éversion et d'inversion de la cheville, de manière à assurer la contention souple de l'articulation sous-astragalienne et accommoder ainsi, au moins partiellement, les mouvements d'éversion et d'inversion de la cheville.

The object of the invention is achieved by means of a multi-purpose shoe, of the sports, walking or rehabilitation shoe type for example, comprising:

• a plantar shell consisting, in particular, of a calcaneal shell and adapted to provide support and reinforcement for the plantar mass of the foot and of the calcaneus-pedious block,
• and a rod connected to the hull by means of a device allowing relative movement between the rod and the hull, characterized in that:
  • . the upper is adapted to support the mass of the foot including part of the talus and at least part of the posterior mass of the foot,
  • . and in that the device consists of a subtalar section having a rigidity lower than that of the rod and the calcaneal shell, so that the rod and the shell are relatively mobile, the subtalar section being mounted between the rod and calcaneal shell by enveloping, at least partially, the foot at the level of a cone of revolution called the subtalar cone and representative of the movements of eversion and inversion of the ankle, so as to ensure flexible compression of the subtalar joint and thus accommodate, at least partially, the movements of eversion and inversion of the ankle.

Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting examples, embodiments of the subject of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS :

Fig. 1 shows a schematic external lateral view of the ankle and foot joint in a shoe according to the invention.

Fig. 2 shows the articulation of the ankle and the foot in a top view taken along line II-II of FIG. 1 .

Fig. 3 shows a first embodiment of a shoe according to the invention shown in a side view.

Fig. 4 shows a side view of a second alternative embodiment according to the invention.

Fig. 5 shows a detail of embodiment of the subtalar bellows according to the invention, according to a front view in section along the line VV of FIG. 3 .

Fig. 6 shows, in a side view, another alternative embodiment of the object of the invention.

Fig. 7 shows a top view of a shoe according to the invention.

BEST WAY TO IMPLEMENT THE INVENTION :

Fig. 1 shows, schematically, the arrangement of the bones constituting the subtalar joint of an ankle 1 of a human being, placed inside a shoe whose outer shell 2 , as well as the sole 3 have been shown in dotted lines. The general view represented can be considered as illustrating the position of the ankle 1 of the right hindfoot of a human being, seen laterally from the outside, in a plane extending in the direction of the main longitudinal axis. of the shoe and substantially perpendicular to the support and extension plane of the shoe materialized by the plane P. The latter can be considered as the support and extension plane of the sole 3 .

The subtalar joint of the ankle is made up of the calcaneus 4 , the talus 5 and a block called calcaneopedious including a set consisting of the cuboid 6 , the scaphoid 7 , then a series of bones represented partially in fig. 1 and including cuneiforms, metatarsals and phalanges.

The talus 5 is connected to the calcaneus 4 via two crossing ligaments 8, 9 . The movements of the subtalar joint in space can be considered as being the result of the relative positions in space of the set of positions of the calcaneus-pedal block relative to the talus 5 . More precisely, these movements are defined conventionally in anatomy by a so-called inversion movement and by a so-called ankle eversion movement.

• dans le plan horizontal confondu, selon la fig. 1, avec le plan P , une rotation dite interne, car dirigée vers la face interne du pied opposé, une telle rotation interne présentant une amplitude maximum, de l'ordre de 30° environ, par rapport à une position d'aplomb normale dans laquelle l'axe longitudinal du pied est sensiblement parallèle au plan de symétrie de l'être humain,
• dans le plan frontal correspondant à un plan F perpendiculaire au plan P un roulis, dit interne, d'une amplitude de 25° environ définie par rapport à deux positions extrêmes dites basse et haute d'amplitude du pied et donc du roulis interne,
• dans le plan sagittal, non représenté aux figures et matérialisé par le plan de la coupe de la fig. 1, une flexion, dite plantaire, d'une amplitude de 10° environ dirigée selon la flèche f ₁ et définie par rapport a une position normale d'aplomb d'un être humain en référence à un plan horizontal.

By inversion of the ankle is meant a movement which associates a combination of movements in the three planes of space, namely:

• in the horizontal plane combined, according to fig. 1 , with the plane P , a so-called internal rotation, since it is directed towards the internal face of the opposite foot, such an internal rotation having a maximum amplitude, of the order of approximately 30 °, relative to a normal plumb position in which the longitudinal axis of the foot is substantially parallel to the plane of symmetry of the human being,
• in the frontal plane corresponding to a plane F perpendicular to the plane P, a roll said to be internal, with an amplitude of approximately 25 ° defined with respect to two extreme positions called low and high amplitude of the foot and therefore of the internal roll,
• in the sagittal plane, not shown in the figures and materialized by the plane of the section in FIG. 1 , a flexion, called plantar, of an amplitude of about 10 ° directed along the arrow f ₁ and defined with respect to a normal plumb position of a human being with reference to a horizontal plane.

The amplitudes, given above with reference, correspond to average values taken from practice, each amplitude being, of course, liable to vary, for example of the order of 5 to 10 ° depending on the age of the individual. and according to its own anatomical characteristics.

• une rotation externe de 30° au maximum dans le plan horizontal,
• un roulis externe d'environ 20° dans le plan frontal F ,
• une flexion, dite dorsale, dans le plan sagittal dirigée selon la flèche f ₂ de la fig. 1 et d'une amplitude de 10° environ.

In the same way, by eversion of the ankle is designated a movement associating, in the three planes and directions of space, a set of movements of the ankle deviating or moving away from a plane of vertical symmetry of the 'individual. These eversion movements can be materialized by:

• an external rotation of maximum 30 ° in the horizontal plane,
• an external roll of approximately 20 ° in the frontal plane F ,
• a flexion, called dorsal, in the sagittal plane directed according to the arrow f ₂ of FIG. 1 and with an amplitude of approximately 10 °.

The investigations and studies carried out by the applicants on the movements and displacements of the subtalar joint of the foot and ankle have shown that all of these inversion and eversion movements, according to the plans and directions of the 'space previously defined, had instantaneous axes of displacement or, again, of movements whose displacement was limited and circumscribed to a geometrical envelope comparable to a cone of revolution 11 hereinafter called sub-talus cone.

The apex S of the cone 11 can be considered to be located at a distance d of the order of a few centimeters, behind the calcaneus 4 and at a height H ₁ substantially equivalent to one third of the height H representative of the height of the posterior edge. extreme of the calcaneus 4 . The vertex S is also located approximately at the center of the geometric projection of the calcaneus 4 on the frontal plane F. The cone 11 also has an inclination relative to the plane P , which can be defined by means of the two beams formed by the ligaments 8 and 9 , the intersection of which is located on the central axis 12 of the cone 11 . In practice, it turns out that the angle α, formed by the intersection of the central axis 12 with the reference plane P , has a value between 20 and 50 ° and, more generally, preferably between 30 and 45 °.

The cone 11 is further defined by its opening angle β ( fig. 2 ), the average value of which varies between 15 and 30 ° depending on the age of the individuals and their anatomical particularities. Fig. 2 shows a top view of a right foot, disposed inside a shoe 2 , in projection on a horizontal plane, such as the plane P , the main longitudinal axis x-x ' of the shoe 2 forming, with l central axis 12 of the cone 11 , an angle γ substantially between 10 and 30 °. For each individual, the subtalar cone 11 therefore has an orientation directed towards the inside of the foot or of the axis of symmetry of the individual.

The set of geometric and angular definitions of the subtalar cone 11 therefore makes it possible to define in space the arrangement and the orientation of the cone inside which the instantaneous axes of movement of the subtalar joint move. The subtalar cone 11 thus constitutes a geometric and mechanical model representative of the kinematics of the ankle joint on anatomical and physiological bases.

Figs. 3 and 7 represent a first alternative embodiment of a multi-purpose shoe according to the invention. The shoe 15 is constituted, in a conventional manner, by a plantar shell 16 able to provide support and reinforcement for the plantar mass of the foot constituted by the calcaneus-pedious block. As shown in fig. 3 , the plantar shell 16 can advantageously consist of a calcaneal shell 17 , more particularly intended to provide support and support for the mass of the foot including the calcaneus 4 and a pedestrian shell 18 , more particularly intended to provide support for the forefoot. The plantar shell 16 is integral with a sole 19 intended to rest on the ground materialized by the plane P.

The compression of the subtalar articulation of the ankle, materialized by the subtalar cone 11 , is ensured by a subtalaral section 21 interposed between the calcaneal shell 17 and a rod 22 , called the intermediate rod and, more particularly, intended to contain the mass of the foot including part of the talus and, at least, part of the posterior mass of the foot. The subtalar section 21 is mounted in the structure of the shoe 15 and arranged in such a way that it envelops, at least partially, the foot at the level of the subtalar cone 11 to ensure the flexible compression of the sub-articulation. astragalar and thus accommodate, at least partially, the movements of eversion and inversion of the ankle. Ideally, the subtalar section 21 covers the articulation to coincide perfectly with the geometry of the cone 11 , but the covering can be limited to a portion of the cone 11 or, on the contrary, cover a larger range. The amplitude of the movements of eversion and inversion allowed varies accordingly and the surface of envelopment of the subtalar section is chosen according to the type of use of the shoe.

The subtalar section 21 is thus comparable to a compression band enveloping the foot and the subtalar joint at the level of the subtalar cone 11 , laterally, posteriorly and, at least in part, anteriorly. The subtalar section 21 follows the inclination general of the cone 11 and its main axis is therefore inclined in the direction of the upper part of the shoe 15 , so that its main angle of inclination forms an angle equivalent to the angle of inclination α of the cone 11 between 20 and 50 ° and preferably between 30 and 45 °.

The posterior zone 23 of the subtalar section 21 is located in the vicinity of the vertex S of the cone 11 and, in the case where the subtalar section 21 covers the anterior part of the foot, the subtalar section covers the angle d β opening of the cone 11 .

To allow the subtalar section 21 to ensure flexible compression of the subtalar joint, it is necessary for the latter to be deformable and of less rigidity than the material constituting the intermediate rod 22 and the calcaneal shell 17 , so that they are relatively mobile. To this end, the intermediate rod 22 and the calcaneal shell 17 can be made of a rigid material or at least having a certain rigidity, based on carbon or composite materials such as carbon-Kevlar or, even, based on certain materials. high density plastics. The subtalar section can be made from any deformable material, of the polymer type or synthetic fabrics for example, the elasticity of which can be varied according to the type of use.

Fig. 5 shows, in a cross section, a detail of construction and mounting of the subtalar section 21 . The latter is, in the example shown, consisting of a subtalar bellows 25 consisting, for example, of folds 26 , substantially circular and concentric and forming an accordion structure enveloping the subtalar joint and whose capacity to deformation accommodates the movements of eversion and inversion of the ankle joint, in correspondence with the subtalar cone 11 . It should be noted that the bellows 25 is arranged so as to wrap the subtalar joint of the ankle so that the cone subtalar 11 projects geometrically along the dotted lines in fig. 5 , along planes parallel to the extension planes P of the sole, at least partially inside the support strip defined by the bellows 25 . The bellows 25 is made integral with the intermediate rod 22 and the calcaneal shell 17 by any suitable means well known to those skilled in the art, for example by stitching or gluing, and disposed outside the shoe, as shown in the fig. 5 , or even internally. A flexible protective loop can be applied and fixed on the bellows 25 . Advantageously, the cone 11 projects completely onto the subtalar bellows 25 , which constitutes an enveloping strip whose front part is wider than the rear part.

During forced articulation movements, for example in eversion, the rigid calcaneal shell 17 can come into abutment, due to the deformation of the talus bellows 25 , against the intermediate rod 22 , the upper face 17 a of the calcaneal shell coming to rest against the underside 22a of the intermediate rod 22.

It is quite obvious that, in place of a subtalar bellows 25 , other mechanical means capable of radiating deformation can be used, insofar as their deformability and rigidity allow the relative mobility of the calcaneal shell 17 and of the intermediate rod 22 .

As a variant, it is also possible, in place of subtalar sections 21 of the attached type, such as the subtalar bellows 25 defined above, to have recourse to a subtalar section 21 directly integrated between the rod intermediate 22 and the calcaneal hull 17 . For this, it is necessary to make the subtalar section 21 , the calcaneal shell 17 and the intermediate rod 22 in the same composite material, for example of the carbon-Kevlar type, but to gradually vary the composition of the material at the level of the envelope representative of the subtalar section. It thus becomes possible, by increasing the density of Kevlar by compared to that of carbon, to decrease the rigidity of the subtalar section 21 , so as to give it a deformation capacity equivalent to that obtained by a subtalar bellows 25 .

Depending on the expected use of the shoe and, in particular, depending on the dynamic stresses required, one or the other of the alternative embodiments of the subtalar section will be preferred.

Fig. 4 illustrates a second variant embodiment of the shoe according to the invention which does not differ from the variant presented in FIG. 3 only by mounting a deformable tibio-tarsal section 31 , mounted above the intermediate rod 22 . The tibio-tarsal section 31 comprises, in combination, a rising leg rod 33 articulated on the intermediate rod 22 at the level of the tibio-peroneal clamp 10 , by means of a monoaxial articulation device 34 . The tibio-peroneal forceps 10 , defining an axis of rotation inclined towards the horizontal plane P from the plane of symmetry of a human being, the monoaxial articulation device 34 has an axis of rotation coincident with said inclined axis. The leg rod 33 may be rigid or be only partially rigid and comprise a flexible part at its upper part, the rigid part being limited in the vicinity of the articulation device 34 .

The tibio-tarsal section 31 is completed by at least one deformable bellows, and preferably two, intended to surround the upper part of the ankle. Preferably, the tarsal deformable bellows will consist of a so-called front bellows 35 and a rear bellows 36 , each bellows having specific opening angles.

The anterior 35 and posterior 36 bellows can be made of a flexible and deformable plastic material, similar to that used for the production of the subtalar section 25 and consist of a series of substantially radial folds giving each bellows an accordion structure. Advantageously, the leg rod 33 can pivot around the axis transverse of the tibio-peroneal forceps 10 , from front to back and, preferably, of an amplitude of the order of 30 to 90 ° and, preferably, close to 45 ° towards the front of the shoe and on the order of 30 to 90 ° and preferably around 60 ° towards the rear of the shoe. The angular values thus defined correspond, approximately, to the respective opening angle of the anterior bellows 35 and the posterior bellows 36 whose deformations on the previously named angular ranges allow the leg rod 33 to come into abutment on the intermediate rod 22 .

The shoe having the tibio-tarsal section therefore allows, in addition to the compression with mobility of the subtalar joint, the compression of the joint at the level of the tibio-peroneal forceps, which, in the case of application to specific sports activities, improves the support of the foot and ankle joints, without negatively affecting the comfort of the user.

In the two examples mentioned above, the opening of the shoe can be carried out, in a conventional manner, by hooking or lacing of the anterior parts of the shoe or, again, by successive interlocking of the various constituent elements of the shoe on the sub-section. astragalian.

The production of a multi-use shoe, comprising a deformable subtalar section, arranged on the shoe according to the subtalar cone 11 representative of the eversion and inversion movements of the ankle, allows, in a simple and effective manner , to obtain a shoe ensuring, at the same time, perfect compression, since respecting the anatomy and physiology of the subtalar joint, and the comfort of the user.

Indeed, the deformation of the subtalar section does not constitute a discomfort for the user, since the arrangement is such that all the natural movements of the subtalar joint are allowed, the contention proper only beginning when the movements of eversion or inversion of the ankle are likely to generate instantaneous axes of displacement being located outside the sub-talus cone. These limit values correspond, then, to the abutment bearing abutment of the calcaneal shell 17 against the intermediate rod 22 which then ensures effective containment of the subtalar joint.

It is quite obvious that, in the case where the compression must be improved; abutment of the calcaneal shell 17 and the intermediate rod 22 can occur before the instantaneous axes of movement reach the limit of the envelope defined by the subtalar cone, which leads to limit the amplitude of movement of the subtalar joint. Such a limitation can, of course, have an advantage in the case of shoes designed for use in motor rehabilitation.

The invention is not limited to the examples described and shown, since various modifications can be made thereto without departing from its scope. Thus, it is possible ( fig. 6 ) to ensure the mounting of the intermediate rod 22 directly on the calcaneal shell 17 , by means of a mono-axial articulation device 40 disposed in the vicinity of the apex S of the cone subtalar 11 , on a posterior covering tongue 41 secured to the intermediate rod 22 . The mono-axial system can advantageously consist of a pivot whose axis is substantially coincident with the main axis 12 of the subtalar cone ( 11 ).

POSSIBILITY OF INDUSTRIAL APPLICATION :

The object of the invention finds a particularly interesting application for the production of sports or rehabilitation shoes.

Claims (12)

1. Multi-purpose shoe, of the sports, walking or re-education type for example, comprising:

   - a plantar shell (16) constituted in particular of a calcaneen shell (17) and adapted to support and reinforce the plantar mass of the foot, and of the calcaneo-pedal block,

   - and an upper (22) linked to the shell (16) via a device which allows for a relative clearance between the rod (22) and the shell (16), characterized in that:

   . the upper (22) is adapted to support the mass of the foot including a portion of the astragal and at least a portion of the rear mass of the foot,

   . and in that the device consists of a sub-astragalar section (21) whose rigidity is less than the rigidity of the upper (22) and of the calcanean shell (17) so that the upper and the shell are relatively mobile, the sub-astragalar section (21) being mounted between the upper (22) and the calcanean shell (17) enveloping, at least partially, the foot at the level of a circular cone called sub-astragalar cone (11) and representative of the eversion and inversion movements of the ankle, so as to ensure the supple support of the sub-astragalar articulation and thus accommodate at least partially the eversion and inversion movements of the ankle.
2. Shoe according to Claim 1, characterized in that the sub-astragalar section (21) is assimilable to a support band enveloping the sub-astragalar articulation laterally, posteriorly and anteriorly.
3. Shoe according to Claim 1, characterized in that the sub-astragalar section (21) is disposed so that the sub-astragalar cone (11) projects along planes parallel to the plane of extension (P) of the sole (19), at least partially inside the envelope defined by the sub-astragalar section (21).
4. Shoe according to Claim 3, characterized in that the sub-astragalar section (21) follows the general inclination of the sub-astragalar cone and is inclined in the direction of the upper part of the shoe, so that its principal angle of inclination forms an angle (α) included between 20 and 50° and preferably included between 30 and 45° with the principal plane of extension (P) of the shoe and presents a posterior zone located in the vicinity of the apex (S) of the sub-astragalar cone (11), as well as an anterior zone covering the aperture angle (β) of the cone included between 15 and 30°.
5. Shoe according to one of the preceding Claims, characterized in that the sub-astragalar section (21) is a bellows (25), added on the upper (22) and the calcanean shell (17) and constituted by folds (26) in correspondence with the sub-astragalar cone (11).
6. Shoe according to one of the preceding Claims, characterized in that the upper (22) is mounted on the calcanean shell (17) via a pivot system (40) disposed in the posterior part of the shoe, in the vicinity of the apex (S) of the sub-astragalar cone (11) and of which the pivot axis is substantiaily merged with the principal axis (12) of the said cone (11).
7. Shoe according to one of Claims 1 to 4, characterized in that the sub-astragalar section (21) is integrated in the shoe (15), between the upper (22) and the calcanean shell (17), and is constituted by the same material as the upper and the shell, but of lesser rigidity.
8. Shoe according to Claim 7, characterized in that the sub-astragalar section (21) is made from a composite material comprising different proportions in order to obtain the lesser rigidity.
9. Shoe according to Claim 8, characterized in that the proportion of the composite materials varies progressively between the upper (22) and the sub-astragalar section (21), on the one hand, and between the latter and the calcanean shell (17) on the other hand.
10. Shoe according to one of the preceding Claims, characterized in that it further comprises a deformable tibio-tarsal section (31) mounted above the upper (22), in combination with a rising leg upper (33) articulated on the upper (22) at the level of the tibio-peroneal grip (10).
11. Shoe according to Claim 10, characterized in that the tibio-tarsal section (31) is constituted by two deformable bellows, one being anterior (35) and the other posterior (36).
12. Shoe according to Claim 11, characterized in that the anterior bellows (35) presents an aperture angle which may vary from 30 to 90 degrees and preferably close to 45°, from the axis of articulation of the leg upper, allowing an angular clearance of the same order of the leg upper (33) towards the front, and the posterior bellows (36) presents an aperture angle which may vary from 30 to 90 degrees and preferably close to 60°, from the axis of articulation of the leg upper (33) allowing an angular clearance towards the rear of the same order of said leg upper.

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