FR2685194A1 - Foot prosthesis - Google Patents

Abstract

The present invention relates to a foot prosthesis (10). This prosthesis is characterised in that it comprises, in combination, a front foot portion (80) comprising a toe section (82), a curved ankle section (94) and a fastening section (92) extending practically vertically, ending immediately above the curved ankle section (94), a heel portion (84) including a fastening section (22), fastened to the front foot portion (80), and a heel section (28) extending towards the rear from the fastening section, and an auxiliary ankle element (86) fixed to the curved angle section (94).

Description

The present invention relates generally to prostheses of

  foot and more particularly a foot prosthesis characterized by a unitary foot and heel construction and / or an auxiliary ankle construction which makes it possible to selectively determine and easily modify the flexibility of the prosthesis The invention also relates to a coupling device improved to attach the prosthesis

  foot to an auxiliary pylon tube.

  The prior art abounds in different types of mechanical devices intended to solve the problem of foot prostheses. A typical example of recent devices is described in US Pat. No. 2,075,583 and this device comprises a rubber shape mounted in operational relation with a metal core. rigid An example of the very latest developments in this field is that which is the subject of US Pat. No. 4,645,509 which comprises a monolithic beam or keel of relatively massive proportions, which is intended to react to the load of the body of an amputee during the walking, running, jumping and similar activities and restoring the resulting accumulated energy in order to create a lifting and pushing of the foot completing the step

natural amputee.

  However, each of the previously known devices has known drawbacks. In particular, the constituent parts of the prosthesis according to US Pat. No. 2,583 are too heavy and too rigid, or those of the prosthesis according to US Patent 4,645,509 are too massive and monolithic to be able to respond appropriately

  in the nuances of the characteristic of the constrained gradient-

human foot response.

  One of the main factors that prevented the creation of a truly satisfactory foot prosthesis, was the fixation according to the prior art with the duplication of the structural aspects of the muscle and bone components of a real human foot. In many cases, as shown by way of example in US Pat. No. 4,645,509, which was mentioned previously, we have even tried to duplicate the toes of the foot in order to provide a dummy of them. It is this fixation on the elements mechanics of the human foot which has limited the technique to an attempt to duplicate the components of a human foot, a tendency which is particularly

  highlighted in US Patent 3,335,428.

  US Patent 5,037,444 sets out certain principles relating to a prosthetic foot characterized by a forefoot portion and a heel portion which can be associated with each other in a permanent or removable manner, so that both the forefoot portion and the heel portion can be easily exchanged with forefoot and heel portions constructed in a corresponding manner This possibility of exchange allows an adjustment of the dimensions or the obtaining different elastic constants so that the prosthesis can adapt to the size of the amputee's foot or to his step and weight, providing the amputee with an almost infinite range of combinations of elastic constants and sizes, and allowing a natural step and elasticity that could not be

  obtained by prostheses according to the prior art.

  The invention described in patent 5,037,444 uses a horizontal fixing surface to attach the prosthesis to a pylon. However, this horizontal fixing surface results in certain limitations with regard to the size, weight and performance of the prosthesis, as well as difficulties and a relatively high manufacturing cost, these limitations not existing in the case of the present invention. An object of the present invention is therefore to provide a foot prosthesis which is characterized by a forefoot portion and a heel portion which can be associated with each other in a permanent or removable manner, the forefoot portion having an upwardly extending securing section, facilitating manufacture and providing resistance against rotation, so that both the forefoot portion and the heel portion can be easily exchanged with forefoot and heel portions constructed in a corresponding manner, to allow adjustment of the size or to obtain different elastic constants to allow adaptation to the size of the foot of the amputee or the pitch and weight of this amputee, and other adjustments can be made using an elastic ankle auxiliary element Therefore an almost infinite combination of elastic constants and size es can be offered to the amputee, giving him a natural step and an elasticity of his approach, which could not be obtained with prostheses according to the technique

anterior.

  Another object of the invention is to provide, in a foot prosthesis of the aforementioned type, a portion of forefoot interchangeable or permanently mounted, which comprises a section of toes, a section of arch, a section of curved ankle and a fastening section extending upwards, all these sections being carried out without it being necessary to progressively reduce their thickness In the abovementioned foot prosthesis is also incorporated a heel portion which has a fixed fastening section at the intersection of the arch and toe sections of the forefoot portion, and a heel section extending beyond the curved ankle and fixation sections of the

forefoot portion.

  As indicated above, the forefoot portion can be made with different dimensions and elastic constants and an auxiliary ankle element can be used, which makes it possible to easily take gait, weight into account. and the level of activity of the amputee Correspondingly the forefoot portion can be detachably associated with the heel portion of the prosthetic foot, in order to allow climbing, in operational relation with the forefoot portion, heel portions having different dimensions and

  different elastic constants.

  Another object of the present invention is to provide a foot prosthesis of the aforementioned type in which the forefoot and heel portions of the prosthesis are both made, and the auxiliary ankle element can also be made, from superimposed layers maintained in operational relation by an encapsulation polymer, and in addition in which the sections of toes, arch, ankle and fixation of the forefoot portion, the heel section of the heel portion, and the auxiliary ankle element are susceptible to bending stresses determined by the number of laminated layers and of polymers in the respective sections of toes, arch, ankle and fixation of the portion forefoot, in the heel section of the heel portion and in the auxiliary ankle element Thus the different portions and sections of the prosthesis are encapsulated in a poly mother and are able to respond to elastic stress when ankle loads are placed on them for

the use of the prosthesis.

  Another object of the present invention is to provide, in a prosthesis of the aforementioned type, a portion of the forefoot which is made up of sections of toes, arch, ankle and fixation which are continuous and formed integrally and simultaneously, these sections being produced as a unitary structure by impregnation, with a polymer, of superimposed reinforcing layers maintained in the desired shape for the forefoot portion, these toe sections, arch, ankle and fixation being able to accumulate energy produced by elastic stress, so that the application of bending moments to the toe section causes a uniform transmission of elastic stress through the arch section and across the curved ankle section of the forefoot portion, up to

the fixing section thereof.

  According to a variant, short cut fibers or another suitable reinforcing material can be used in place of the aforementioned laminated layers or in addition to these. Another object of the invention is to provide the abovementioned foot prosthesis in which the curved ankle section of the forefoot portion has its upper end which is constituted by the upper fixing section, while its lower end s extends towards and into the arch section, constituting this last section, this lower end, the curved ankle section and the upper fixation section retaining a substantially uniform thickness in the transverse direction relative to the longitudinal axis of these sections Similarly, the heel portion and its various sections have a substantially uniform thickness in the transverse direction by

  relative to the longitudinal axis of these sections.

  Another object of the present invention is to provide the element of the auxiliary ankle which is associated with the ankle section of the forefoot portion in order to increase the resistance of the ankle section with respect to the loads. which are applied to the toe section of the forefoot portion The principle of the auxiliary ankle element involves the provision of ankle elements characterized by different elastic constants, which makes it possible to precisely adjust the resistance, flexion, of the ankle section to the weight, activity level and other characteristics of the individual to be

adapted the prosthetic foot.

  The polymers used to encapsulate the fibrous layers are characterized by elasticity and flexibility so that the forefoot and heel portions flex in proportion to the extent of contact of the forefoot portion with an adjacent surface, which causes the resulting energy to be stored and then to be restored when the amputee's gait, comprising thrust and lift components, results in the use of the accumulated energy and in a correlative reduction of the energy expended by the amputee There is a progressive increase in stiffness as the lever arm of the toe section of the forefoot portion becomes shorter due to its progressive flexion. An additional object of the present invention is to provide an improved coupling mechanism for attaching a foot prosthesis of the aforementioned type to a pylon tube

  auxiliary which is in turn attached to the wearer's leg.

  To give an aesthetic appearance to the prosthetic foot, once the appropriate adaptation of this prosthesis has been made to ensure that the forefoot and heel portions and the auxiliary ankle element are balanced in an appropriate manner and d '' a suitable size, the prosthesis can be encapsulated in an envelope of appropriate shape, similar to a foot, in order to facilitate the use of the prosthesis of foot with a running shoe The envelope must be flexible enough not to prevent movement free and flexing of the forefoot and heel portions and of the auxiliary ankle element of the foot prosthesis but, owing to the inherent elasticity and stress absorption characteristics of the foot prosthesis, is necessary to have a low dependence on the action

  auxiliary damping of the envelope.

  Consequently, the foot prosthesis according to the invention is characterized by its very light weight, by an instantaneous response to the applied loads and by a corresponding instantaneous restitution of the energy accumulated when the wearer's gait indicates that the energy thus accumulated must be In addition, the foot prosthesis can be easily mounted in operational relation with pylons and usual auxiliary coupling devices and can be finely adjusted by the combination of the characteristics of the forefoot and heel portions and the auxiliary ankle element, in order to finally obtain the

  better operational response to the wearer's needs.

  Consequently, the wearer of the prosthetic foot can engage in a wide variety of activities which were prohibited to him in the past because of the structural limitations and corresponding performances of the prostheses according to the prior art Running, jumping and other activities are very well accepted by the prosthetic foot and it can be used in the same way as the normal foot of the wearer. An embodiment of the present invention will be described below, by way of non-limiting example, with reference to the attached drawing in which: FIG. 1 is a side elevation view of a

  portion of a prosthesis constructed according to the invention.

  Figure 2 is a plan view, partially in section

  along line 2-2 in Figure 1.

  Figure 3 is a front view of the prosthesis, taken

  along line 3-3 in Figure 2.

  FIG. 4 is a view in vertical section and

  longitudinal made along line 4-4 of figure 2.

  If we refer to the drawings and in particular to FIGS. 1 and 2, we can see that a foot prosthesis 10,

  built according to the invention, comprises a portion of

  foot 80 and a heel portion 84 which are operatively connected to one another, in a removable manner, by means of combinations 104 of the screw-nut type, associated with metal load transmission plates 106 If this is necessary, the forefoot and heel portions can be permanently fixed to each other, by

  example using epoxy adhesive or the like.

  The forefoot portion 80 of the prosthesis 10 comprises an upper fixation section 92, which is substantially rigid, a curved ankle section 94, a arch section 96 and a toe section 82 The sections 92, 94, 96 and 82 of the forefoot portion 80 are preferably formed in one piece with each other and simultaneously by the incorporation of a plurality of layers embedded in a flexible polymer cured According to a variant of the short fibers cut or another suitable reinforcement material may be used in place of

  aforementioned layers or in addition to these.

  The fixing section 92 has two central openings 88 (FIG. 4) The fixing section 92 is substantially rigid and is capable of absorbing torsional loads, shocks and other loads which are applied to it by the portion of forefoot 80 and by the heel portion 84 of the prosthesis Furthermore, the inherent rigidity of the fixing section 92 results in the effective transmission of the aforementioned loads, which are applied to it, to a suitable auxiliary prosthesis pylon 30, by means of combinations 98 of the screw-nut type, assembled through the openings 88 with a device 90 for coupling to the pylon A screw 100 or another suitable fixing means secures the pylon

  auxiliary 30 in the coupling device 90.

  In the particular embodiment shown in Figures 1-4, the auxiliary dowel element 86 is mounted

  between the coupling device 90 and the front portion

  foot 80 and it is fixed, in operational relation with the ankle section 94 of the forefoot portion 80, by means of central openings provided in the fixing section 102 of the auxiliary ankle element 86, these openings being practically aligned with the openings 88 of the fixing section 92 of the forefoot portion The combinations 98 of the screw-nut type keep the various components in their aforementioned operational relationship. According to an alternative embodiment, the element could be fixed. auxiliary ankle

  86 to a posterior surface of the fixing section 92.

  In the preferred embodiment, combinations 104 of the screw nut type are used, together with metal plates 106 for distributing the loads, to fix the heel portion 84 in its operational relationship with the forefoot portion 80 of the prosthesis. This method of attachment facilitates the mounting or dismounting of selected heel portions 84, in operational relation with selected forefoot portions 80, which makes it possible to obtain a wide range of different dimensions and different response characteristics to a stress load, in order to obtain the optimal functional correspondence between the

  forefoot 80 and heel 84 portions.

  il Auxiliary peg element 86 can be used

  to decrease the flexibility of the forefoot portion 80.

  The auxiliary ankle member 86 is formed from fibrous layers of the same type as those of the various portions of the prosthesis. In the preferred embodiment the auxiliary ankle member 86 has a securing section 102 which is operationally associated to the coupling device 90 and to the upper fixing section 92 of the forefoot portion 80, being preferably situated therebetween The auxiliary ankle element 86 is preferably fixed in operational relation with the section curved ankle 94 of the forefoot portion 80, by means of the aforementioned assembly of the coupling device 90 and combinations 98 of the screw-nut type At its extreme part which is opposite to the fixing section 102, the auxiliary ankle element 86 has a tapered section 108 which gives variable flexibility along the length of the auxiliary ankle element 86 and which also reduces the probability to see the auxiliary ankle element 86 being hooked or retained in an undesirable manner in its cooperative relationship with the forefoot portion 80 and the aesthetic envelope of the prosthesis, which will be studied in a more complete below According to a variant, as will be understood by those skilled in the art, such a gradual reduction in thickness is not required for the implementation of the invention and therefore the auxiliary dowel element 86 could be provided with a thickness

  substantially uniform along its length.

  In the preferred embodiment the auxiliary ankle member 86 is fixed against the internal or concave curved surface of the curved ankle section 94 so that the predictable upward bending of the toe section 82 of the forefoot portion 80, as will be described more fully below, possibly causes deformation of the auxiliary ankle element 86 and also a deformation of the ankle section 94, thereby effectively combining the resistance characteristics to the deformation and energy storage of the auxiliary anchor element 86 with those of the anchor section 94 According to an alternative embodiment, the auxiliary anchor element 86 could be fixed to the rear surface of the fixing section 92 and one could also fix the tapered section 108 of the auxiliary dowel member to a lower surface 62 of the dowel section 94 to obtain the combination above-mentioned area of the resistance to deformation and energy storage characteristics of the auxiliary anchor element 86 with those

of the dowel section 94.

  The auxiliary anchor element 86 can be provided with different numbers of laminated layers in order to make it more or less flexible with respect to the loads transmitted through the ankle section 94 Consequently, when various anomalies are faced in an amputee, such as excessive weight or excessive activity levels, the basic structure of the forefoot portion 80 and more particularly the ankle section 94 can be modified materially in order to obtain an action of the ankle section which is precisely adapted to the needs of the amputee Furthermore, an amputee can have a wide variety of auxiliary ankle elements 86, which makes it possible to adapt the flexibility of the prosthesis according to

  the particular activity to which the amputee engages.

  As mentioned above, an aesthetic envelope, not shown, may be provided to surround the prosthesis 10 after the optimal assembly of the forefoot 80 and heel 84 portions and any ankle element auxiliary 86 has been made However, unlike constructions according to the prior art, the aesthetic envelope, which can be formed from a low density polymer, must not be used for an auxiliary shock absorption function or another stress isolation function since all the loads applied to the prosthesis can be absorbed, transmitted and restored in a manner which will be described in more detail

far.

  Combinations 104 of the screw-nut type, together with the metal load distribution plates 106, serve to fix the heel portion 84 in operational relation with the forefoot portion 80 of the prosthesis 10, as can best be see Figures 1 and 2 of the drawings This method of attachment facilitates the mounting or dismounting of selected heel portions 84 in operational relation with selected forefoot portions 80 of the prosthesis 10, which allows a wide range of different dimensions and of different characteristics of response to a stress load to be associated with each other to obtain the optimal functional correspondence between the forefoot 80 and heel 84 portions, in order to be able to satisfy, in the most large measure, the needs of the prosthesis wearer, and also to allow an appropriate connection of the prosthesis 10 to a pylon

  selected auxiliary 30 or similar.

  The forefoot portion 80 comprises, as can best be seen in FIG. 1, a toe section 82, a arch section 96, a curved ankle section 94 and a fixing section 92 The portion of heel 84 has a securing section 22 and a heel section 28 the posterior end 56 of which preferably extends beyond an extreme posterior surface 58 of the securing section 92 of the forefoot portion of prosthesis 10 Corresponding holes, not shown, drilled in the arch section 96 of the forefoot portion 80 and in the heel portion 84 receive the respective combinations 104 of the screw-nut type, in order to facilitate mounting and dismantling the forefoot 80 and heel 84 portions. In the preferred embodiment, the different sections of the forefoot portion 80 are all made without it being necessary to gradually reduce their thickness, although that the men of the trade will understand that the invention is not

  limited to such a construction without tapering.

  Between the lower surface 62 of the ankle section 94 of the forefoot portion 80 and an upper surface 64 of the heel section 28 is interposed an elastic functional block 70, acting as a spring, in the form of a wedge, in order to determine the lever arm of the heel section 28 and to isolate from each other the lower surface 62 of the ankle section 94 and the upper surface 64 of the heel section 28 The functional block 70 can be made from a wide variety of elastic materials, including natural and synthetic rubbers and

similar matters.

  The materials of which the forefoot portion 80 and the heel portion 84 as well as the auxiliary ankle element 86 are made, must be such as to give a

  elastic, spring-like energy accumulation effect.

  This is necessary because each contact of the prosthesis 10 with an adjacent surface causes the application of compression, torsion and other loads on the prosthesis 10, loads which must be accumulated in the prosthesis and then be reapplied, depending the step of the wearer, on the surface, in order to obtain a natural step ideally conforming, in all respects, to the step of the leg not

  mutilated wearer of the prosthesis 10.

  The forefoot 80 and heel 84 and auxiliary ankle member 86 of the prosthesis are preferably molded as unitary components and are carefully formed to ensure uniform absorption of the stress which is imposed The configuration of the two portions 80 and 84 is of the greatest importance and the short cut fibers, the laminated layers or other reinforcing materials, as well as the polymer or polymers, from which the portions 80 and 84 are made , must be elastic and capable of absorbing the compressive, torsional and other stresses which have been mentioned above and of restoring the accumulated energy created by these stresses, in a natural manner, to the surface serving as support and who originally imposed these constraints on the

prosthesis 10.

  It has been found that there are a limited number of polymers which are capable of absorbing the significant stresses and repetitive loads imposed on the prosthesis 10, in particular taking into account the incalculable number of cycles to which the prosthesis 10 is subjected during use. normal of

everyday.

  Currently the best materials for the prosthesis are a composite material of high strength graphite fibers in a thermosetting epoxy resin with high hardness There are several reasons for this namely (1) high strength, (2) the ratio between stiffness and the weight of graphite compared to other materials; (3) almost total recovery of the energy supplied or accumulated, (4) a light weight (5) a high fatigue strength; and (6) minimal creep As a material variant a composite material of the glass fiber / epoxy resin type is a good choice but it is not as good as graphite because of its lower fatigue strength and its density. higher The material known as "KEVLAR" is also less acceptable because of its poor compressive and shear strengths, although it

  has the lowest density among the aforementioned materials.

  An important aspect of the polymers and of the short cut fibers or of the laminated layers which have been mentioned above, is that they are characterized by bending under non-excessive load, this characteristic allowing the stress of the prosthesis 10 to be stressed. shock absorption while maintaining stability

  sufficient to prevent crushing of the front portions

  foot 80 and heel 84 and the auxiliary ankle element

  86 of prosthesis 10 when loads are applied to them. To obtain the relatively thin construction of the forefoot portions

  80 and heel 84 and the auxiliary ankle element 86 of the prosthesis 10, the abovementioned polymers are used in conjunction with various reinforcing or laminating materials Various types of fibrous layers can be used to obtain the continuity required by the model of forefoot 80 and heel 84 and by the auxiliary ankle element 86 to complete the stress absorption and energy storage characteristics of the polymers in which the layers

fibrous are coated.

  Naturally there is a wide variety of fibrous reinforcements currently available in the form of laminated layers, comprising inorganic fibers such as glass or carbon fibers. These inorganic fibers are usually supplied in the form of a strip or a sheet. and they can be easily superimposed in the mold, in order to allow them to be encapsulated in the selected polymer. As indicated above, the fibers can also be cut or present in a

other form.

  It is obvious that the number of superimposed layers or other reinforcing layers and their lengths, together with the thickness of the encapsulating polymer, determine the stress characteristics of the resulting portions of forefoot 80 and heel 84 and of the auxiliary ankle element 86, and determine, in a corresponding manner, the total weight of the prosthesis 10 As will emerge from the

  description which follows, the individual portions before

  foot 80 and heel 84 and the auxiliary ankle element 86 are designed to adapt particularly to individuals with feet of different sizes, different weights and different gaits, and the individual model of the forefoot portions 80 and heel 84 and the auxiliary ankle element 86 provides an adaptation, to an extent hitherto unknown in the art, to the natural characteristics of

the wearer's non-mutilated leg.

  In addition the functional block 70 can be provided with different dimensions and in materials having different compression characteristics so that the lever arm and the corresponding flexions of the heel section 28

  can be increased or decreased.

  As previously mentioned, the dowel section 94 forms a single piece with the upper fixing section 92 and this fixing section constitutes the upper end of the dowel section 94, while the start of the arch 96 of the forefoot portion 80 constitutes the lower end of the ankle section 94 The configuration of the ankle section 94, together with the auxiliary ankle member 86, is the means by which loads of compression which are applied when the forefoot 80 and heel 84 portions strike an adjacent surface, are absorbed and then reapplied on this surface The ankle section 94 and the auxiliary ankle member 86 are designed such that '' they function almost like an ankle joint to allow the forefoot portion 80 to pivot around them in a manner similar to the way the he normal foot pivots around the joint of a normal ankle, around a transverse axis of this joint. The radii of curvature of the ankle section 94 and any auxiliary ankle member 86 correspond to give the inherent elasticity and flexion of the forefoot portion 80, while preventing

  undesirable excessive crushing of the ankle section 94.

  Note that the securing section 22 of the heel portion 84 is substantially rigid and that the initial bending of the heel section 28 occurs immediately in the immediate vicinity of the posterior end 56 of the heel section, ending immediately in the vicinity of the functional block 70 It is obvious that a functional block 70 having a greater length or less elasticity causes a reduction in the lever arm of the heel section 28 of the heel portion 84 and a correlative reduction in the modulus of bending of the ankle section, while a functional block 70 having a shorter length or greater elasticity causes an increase in the lever arm and a corresponding increase in the bending of the section of ankle

  heel 28, under the effect of a load.

  The toe section 82 and the heel section 28 can be made with different lengths in order to

  correspond to the size of the prosthesis wearer's foot 10.

  When such different lengths are provided, a corresponding reduction or increase in the number of layers and the thickness of the tapered portion of the respective sections of toes 82 and heel 28 can be made to obtain

  proper flexion of these toe and heel sections.

  It should also be noted that even with the section of

  shortest heel 28, rear end 56 thereof

  ci still projects, preferably, beyond the rear surface 58 of the forefoot portion 80 Consequently, the stabilization and stress absorption characteristics of the heel section 28 of the prosthesis 10 are

still preserved.

  Those skilled in the art will understand that many variations of the coupling device 90 can be constructed and used in practice, interchangeably, in conjunction with the many variations

  of the rest of the invention.

  It will naturally be obvious to those skilled in the art, with respect to any embodiment of the invention, that the fibrous reinforcements in the form of layers encapsulated in the prosthesis can be tapered in order to produce a gradual transition when the number of layers is reduced in any area of the portions

forefoot or heel.

  In addition, if a relatively light individual practices sports or other activities which subject the prosthesis 10 to greater loads, it is then possible to adapt a portion of heel 84 or forefoot 80 making it possible to collect

these larger charges.

  The ankle section 94 of the forefoot portion 80 flexes under the effect of a load and in the same way the auxiliary ankle element 86 also bends the toe 82 and arch section 96 of the forefoot portion 80 and the heel section 28 of the heel portion 84 flex under the effect of such a load Therefore, when subjected to vertical compressive loads, the ankle section 94, the auxiliary ankle member 86, the arch section 96 and the toe 82 and heel 28 sections absorb these loads. Consequently, there is no stress concentration either during the impact phase when the adjacent surface is initially encountered by the wearer of the prosthesis 10, or when the restitution of the forces

  accumulated, stored in prosthesis 10, is performed.

  The curvature of the toe section 82 ensures maximum adaptation of this section, during contact with the surface, both during the impact and energy restitution phases of the prosthesis 10 Similar considerations apply at the curvature of the heel section 28 of the heel portion 84 of the prosthesis 10 It should be noted that the curvatures of the toe sections 82 and heel 28 result in relatively large lever arms which make it possible to obtain stability and also the storage of

  constraints and their reaction.

  The preferred method for manufacturing the forefoot 80 and heel 84 and auxiliary ankle element 86 portions of the prosthesis 10 is a thermosetting molding method comprising the use of molds having imprints of shapes and appropriate dimensions The cavities are designed to receive the required number

  layers and the appropriate volume of polymer.

  Unlike the unitary devices according to the prior art, the adaptation of the prosthesis 10 implements the judicious adjustment of the prosthesis by the appropriate combination of the forefoot 80 and heel 84 portions and the element of auxiliary anchor 86 It also implements the selection of the appropriately designed auxiliary pylon 30 which can be fixed, by means of the coupling device 90, to the fixing section 92 of the forefoot portion 80 C It is only when the appropriate relationship between the forefoot portion 80, the heel portion 84, the auxiliary ankle element 86 and the auxiliary pylon has been established that the aesthetic envelope, not shown, can be installed on the portions

  respective prosthesis assemblies 10.

  By means of the prosthesis according to the invention, a foot is obtained which can be adapted with precision to the weight, the step and the physical characteristics of its wearer. This is achieved by carefully balancing the respective physical characteristics of the forefoot portion. 80, the heel portion 84, the auxiliary ankle element 86 and

of their various sections.

  Furthermore, the assembled prosthesis is much lighter than the prostheses according to the prior art since the inherent structure and model of the prosthesis, the materials used and the precise calculation of the stress factors of the components of the prosthesis allow precise adaptation.

  of the prosthesis to the needs of its wearer.

Claims (19)

  1 foot prosthesis (10) characterized in that it comprises, in combination, a forefoot portion (80) comprising a toe section (82), a curved ankle section (94) and a section of fixing (92) extending   practically vertically, ending immediately above   above the curved ankle section (94), a heel portion (84) having a fastening section (22), attached to the forefoot portion (80), and a heel section (28) extending backward from the securing section, and an auxiliary dowel member (86) attached to the securing section curved dowel (94).   2 prosthetic foot according to claim 1 characterized in that the heel portion (84) is removably attached to the forefoot portion (80) so as to allow heel portions (84) having different elastic constants to be attached to the portion   forefoot (80) of the foot prosthesis.   3 Foot prosthesis according to any one of   claims 1 or 2 characterized in that the element of   auxiliary pin (86) constitutes a spring in abutment against the curved pin section (94) and fixed in relation operational with it.   4 Foot prosthesis according to any one of   claims 1 or 2 characterized in that an element   an elastic spring (70) is inserted between a lower surface (62) of the forefoot portion (80) and an upper surface (64) of the heel portion (84), these overlapping surfaces. Foot prosthesis according to any one of   claims 1 or 2 characterized in that the portion   forefoot is made from superimposed layered layers maintained in operative relationship by means of an encapsulating polymer and the ankle (94) and toe (92) sections of the forefoot portion ( 80) are liable to be subjected to bending stresses determined by the dimensions of the layers in the respective sections of ankle (94) and toes (82) of the portion forefoot (80).   6 foot prosthesis according to claim 5 characterized in that the heel portion (84) is manufactured from superimposed layers encapsulated in a polymer and capable of responding to an elastic stress when loads of the ankle are applied to it during   the use of the prosthetic foot.   7 Foot prosthesis (10) characterized in that it comprises, in combination, a forefoot portion (80) consisting of fixing sections (92), curved ankle (94), arch (96) and toes (82) which are continuous and integrally formed simultaneously, these sections being fabricated as a unitary structure, the ankle (94), arch (96) and toe (82) sections being capable of storing energy produced by elastic stress so that the application of bending moments to the toe section (82) causes uniform transmission of elastic stress through the arch sections (96 ) and curved ankle (94), up to the fixing section (92), a heel portion (84) fixed to the forefoot portion (80), this heel portion (84) having one end posterior (56) extending beyond the curved ankle section (94) of the portion d forefoot (80) of the prosthetic foot, and an auxiliary ankle element (86) superimposed on the ankle section (94), this auxiliary ankle element (86) being capable of ensuring a significant amount of storage energy during the use of the foot prosthesis,   plus energy storage of the forefoot portion (80).   8 prosthesis according to claim 7 characterized in that an elastic element (70) is inserted between a lower surface (62) of the arch section (96) of the forefoot portion (80) and a upper surface (64) of the heel portion (84), these overlapping surfaces. 9 Foot prosthesis according to any one of   claims 7 or 8 characterized in that the section of   ankle (94) of the forefoot portion (80) has an upper end constituted by the fixing section (92) and a lower end extending towards and in the arch section (96) and constituting this section , this lower end, the arch section (96) and the toe section (82) having a thickness gradually decreasing towards one end of the section toes (82).   10 Foot prosthesis according to any one of   claims 7 or 8 characterized in that the portion of   heel (84) is detachably attached to the forefoot portion (80) so as to facilitate attachment of the heel portion (84) to the forefoot portion (80) and the removing this heel portion (84) from the forefoot portion (80), in order to allow the substitution of forefoot portions (80) having different elastic constants. 11 prosthetic foot according to claim 10 characterized in that the heel portion (84) has a securing section (22) and a heel section (28), tapered rearward, which ends at the rear of the section ankle (94).   12 Multi-portion foot prosthesis characterized in that it comprises, in combination, an upper unitary foot portion (80), having an attachment section (92) extending upwards and an ankle section (94) extending downward and opening forward, and also comprising arch (96) and toe (82) sections, all of which are formed integrally and simultaneously with each other others, an auxiliary ankle member (86) surmounting the ankle section (94), and a lower foot portion (84) having an anterior end attached to the underside of the upper foot portion (80) and a posterior end extending beyond the ankle section (94) of the upper foot portion (80), the auxiliary ankle member (86) being capable of providing a significant amount of energy accumulation during use of the prosthetic foot, in more energy storage provided by the portions   lower foot (84) and upper foot (80).   13 prosthetic foot according to claim 12 characterized in that the fixing section (92) is constituted by an upper arm of the ankle section (94) and a lower end of the ankle section (94) constitutes the beginning of the arch section (96)   of the upper leg portion (80).   14 foot prosthesis according to claim 13 characterized in that an elastic spring element (70) is inserted between a surface, located on the side of the ankle, of the arch section (96) of the upper foot portion, and an upper surface (64) of the lower leg portion (84).   Foot prosthesis according to Claim 13, characterized in that the lower foot portion (84) is detachably fixed to the upper foot portion (80) in order to allow the substitution of lower foot portions (84) having different elastic constants in operational relation with the upper foot portion (80) of the foot prosthesis.   16 foot prosthesis according to claim 13 characterized in that the auxiliary ankle element (86) is resiliently biased, it abuts against the ankle section (94) and it is fixed in operational relation with it.   17 foot prosthesis according to claim 13 characterized in that the upper foot portion (80) is tapered from a lower end of the ankle section (94) to one end of the toe section (82).   18 foot prosthesis according to claim 17 characterized in that the lower foot portion (84) has a securing section (22) and a heel section (28) which is tapered gradually and uniformly from its intersection with the section fastening (22), to a   posterior end (56) of the heel section (28).   19 Foot prosthesis comprising a fixing means for attaching the prosthesis to the stump of a wearer, characterized in that it comprises, in combination, a J-shaped forefoot portion (80), this shaped portion of J (80) comprising a fixing section (92) operationally associated with the fixing means (98), this fixing portion (92) having sufficient strength to be able, in operation, to transmit and resist forces applied to the prosthesis during use thereof, a curved dowel section (94) immediately adjacent to the attachment section (92), and a section   toes (82) extending forward, this front portion   J-shaped foot (80) being capable, during walking, of storing energy and of restoring it thereafter, without it being necessary to provide for any accumulation of energy and for its restitution in a element additional pylon (30).   20 foot prosthesis according to claim 19 characterized in that the vertical fixing section (92), the curved ankle section (94) and the toe section (82) are integrally manufactured so as to provide a storage of energy produced by elastic stress, so that the application of bending moments to the toe section (82) causes uniform transmission of elastic stress through the ankle section   curve (94), towards the fixing section (92).   21 Foot prosthesis according to any one of   claims 19 or 20 characterized in that it comprises   besides a heel portion (84) operatively attached to the forefoot portion (80) in the form of a J. 22 Foot prosthesis according to claim 21 characterized in that the heel portion (84) is fixed in a removable manner to the forefoot portion (80) in the form of a J. 23 Prosthetic foot according to any one of   claims 19 or 20 characterized in that it comprises   in addition to an auxiliary anchor element (86) fixed to the section curved ankle (94).   24 Foot prosthesis characterized in that it comprises, in combination, a forefoot portion (80) comprising a toe section (82), a curved ankle section (94), and a fixing section ( 92), this fixing section (92) having an upper end, extending vertically, terminating immediately above the dowel section (94), this upper end being arranged operationally so as to allow easy fixing to the wearer , the forefoot portion (80) being capable of storing energy and then restoring it during walking, without it being necessary to provide any energy accumulation and restitution of this   energy in any additional pylon element (30).   Foot prosthesis according to claim 24 characterized in that it comprises an auxiliary ankle element (86) operatively fixed to the section of curved dowel (94).   26 Foot prosthesis according to any one of   Claims 24 or 25 characterized in that it comprises   a heel portion (84) having an attachment section (22) attached to the forefoot portion (80) and a heel section (28> extending rearward from the attachment section. 27 prosthetic foot according to claim 26 characterized in that the heel portion (84) is fixed in a removable way.