WO2023012160A1

WO2023012160A1 - Prosthetic foot, particularly for a leg prosthesis

Info

Publication number: WO2023012160A1
Application number: PCT/EP2022/071694
Authority: WO
Inventors: Daniel Vafi; Maximilian CALABRO; Simon OSCHWALD; Laura MAGNI; Fabian Engel
Original assignee: Verein Project Circleg
Priority date: 2021-08-02
Filing date: 2022-08-02
Publication date: 2023-02-09

Abstract

The present invention relates to a prosthetic foot (1), comprising: a sole (10) comprising a bottom side (10a) for contacting the ground upon walking, the sole (10) further comprising a heel portion (11), an intermediary portion (12) and a front portion (13), wherein the heel portion (11) is integrally connected to the front portion (13) via said intermediary portion (12) in particular, wherein the sole (10) is formed out of a fiber reinforced thermoplastic.

Description

Prosthetic Foot, particularly for a leg prosthesis

Specification

The present invention relates to a prosthetic foot, particularly for a leg prosthesis.

It is estimated, that worldwide almost 90% of people in need for a prosthesis or orthosis do not have access to an adequate device. A significant number of these amputees is missing at least one lower limb and is living in low-income countries where advanced prosthetic devices are not affordable or available. To improve the quality of life of these people in need by providing them with a new leg, there is a strong need to provide a cost-efficient lower limb prosthesis, particularly components thereof that undergo elastic deformation such as a sole and therefore require a careful design.

An important part of the prosthesis for a natural walking gait is the ankle-foot complex. Particularly the foot can be subdivided into a sole which takes over the function of a physiological foot and an ankle joint which can be fixated during walking but can be released allowing a e.g. a squatting position.

Based on the above, it is a main objective of the present invention to provide a prosthetic foot that can be produced in a cost-effective manner.

Furthermore, particularly, it is also desirable to create a prosthetic foot that can be easily and cost-effectively adapted to the various foot geometries of individual users as well as to their respective weight.

The subject is solved by a prosthetic foot having the features of claim 1 as well as by a method having the features of claim 18. Preferred embodiments of these aspects of the present invention are stated in the dependent claims and are described below.

According to claim 1 a prosthetic foot is disclosed, comprising:

- a sole comprising a bottom side for contacting the ground upon walking, the sole further comprising a heel portion, an intermediary portion, and a front portion, wherein the heel portion is connected to the front portion via said intermediary portion, wherein according to the invention the sole is formed out of a fiber reinforced thermoplastic.

Particularly, according to an embodiment, the heel portion is integrally connected to the front portion via said intermediary portion. Here, the sole preferably forms a monolithic body.

According to an alternative embodiment, the sole can have a first part comprising the heel portion and a second part comprising the front portion, wherein the two parts are connected to one another, particularly by means of a releasable connection (e.g., a connection using at least one bolt or the like). Here, the intermediary portion can be formed by a section of the first part and a section of the second part. In other words, the above defined heel portion, intermediary portion and front portion do not necessarily have to be formed integrally themselves, but can each consist of several parts.

Advantageously, the stiffness of the sole can be easily influenced by varying the thickness of the sole. Heavier users need a thicker sole than lighter users.

During a possible production process of the sole (e.g. by means of compression molding), the fiber reinforced thermoplastic (such as GMT or glass mat thermoplastic, particularly X103F61-4/1-0/90⁰ of Mitsubishi Chemical Advanced Materials Composites) can be heated up in an oven and then placed into a mold representing the geometry of the final sole where it gets compressed and takes the final shape as will be described in more detail below. Advantageously, such a process allows to use the same mold for several thicknesses. The Thickness of the final sole is a direct result of the amount of material inserted into the mold.

So far, significantly more expensive carbon composite materials are mainly used in parts of prostheses, particularly prosthetic feet, that are dynamically loaded, but fiber reinforced thermoplastic materials have not been used for soles of foot or leg prostheses since such materials are typically limited to static parts that do not experience periodic deformation as a sole which undergoes a large number of dynamic loading cycles during its lifetime.

However, it has surprisingly been found that a sole being formed as a monolithic body out of a fiber reinforced thermoplastic performs well and can be adapted to exhibit a desirable linear force deflection characteristic over a wide range of deflections of the sole as can be inferred e.g. from Fig. 14. Furthermore, during the process required strength and material characteristics can be fine-tuned by varying pressure and temperature of the compression molding process. Furthermore, the characteristic of the sole can be influenced by the distribution of the material inside the mold.

Particularly, the material that is preferably used in the context of the present invention for the sole, particularly for the heel part and the arch-shaped part (see further down below) is normally not used at all for applications where such large deformations take place as in a prosthetic foot. The usual load cases are static loads and vibration loads. A sole as particularly used in a prosthetic foot according to the present invention has very high requirements for bending behavior, depending on the size of the sole and the body weight of the user. In addition, the sole must withstand enormously high cyclic loads, which directly counteracts the pleasant bending behavior. By cleverly weighting these requirements, taking into account the anthropometric constraints of a user group of approx. 1.50m to 1.90m body height and minimum component weight, the soles (either in an integral shape or consisting of a separate heel and arch-shaped part) according to the present invention satisfy the above-stated desired characteristics due to their design. Particularly, the variation of the profile thickness for components produced by pressing allows the sole to withstand relatively high loads while providing a desired bending behavior at the same time.

According to an embodiment, the fiber reinforced thermoplastic comprises a plurality of layers comprising randomly oriented fibers embedded in the thermoplastic. Alternatively, the fiber reinforced thermoplastic may also comprise regularly oriented fibers.

Furthermore, in an embodiment, the fiber reinforced thermoplastic comprises a plurality of fabric layers comprising fibers embedded in the thermoplastic.

Further, in an embodiment, the fiber reinforced thermoplastic comprises first fibers extending along a longitudinal axis of the sole and second fibers extending perpendicular to the first fibers (and particularly along the top or bottom side of the sole), the first and the second fibers being embedded in the thermoplastic. Particularly, the fiber density of the first fibers is larger than the fiber density the second fibers. Particularly the fiber density of the first fibers twice as large, particularly three times as large, preferably at least four times as large as the fiber density of the second fibers in the fiber reinforced thermoplastic. Furthermore, according to a preferred embodiment of the present invention, the thermoplastic is formed by or comprises polypropylene.

Further, in all embodiments, the randomly oriented fibers and/or said fibers of the fabric layers are preferably glass fibers. However other fiber materials are also conceivable.

Furthermore, in an embodiment, the heel portion, the intermediary portion and the front portion each comprise a thickness orthogonal to the bottom side, the thickness of the intermediary portion being larger than or equal to the thickness of the front portion and of the heel portion.

Particularly, in an embodiment, the thickness of the heel portion is preferably in the range from 5 mm to 20 mm, more preferably 5 mm to 15 mm. Furthermore, in an embodiment, the thickness of the intermediary portion is preferably in the range from 5 mm to 20 mm, more preferably 5 mm to 15 mm. Furthermore, in an embodiment, the thickness of the front portion is preferably in the range from 5 mm to 20 mm, more preferably 5 mm to 15 mm. Particularly, these embodiments regarding thickness of the individual portion of the sole can be arbitrarily combined with one another.

According to yet another embodiment, the intermediary portion comprises a concave curvature on the bottom side of the sole.

Furthermore, in an embodiment, the sole comprises a top side facing away from the bottom side.

According to a preferred embodiment, the intermediary portion comprises a convex curvature on the top side.

Particularly, in an embodiment, the intermediary portion is configured to be connected to an ankle part of the prosthetic foot. In this regard, according to an embodiment of the prosthetic foot, the latter comprises an ankle part, the ankle part being connected to the intermediary portion via at least one threaded bolt being secured with a nut. Particularly, the intermediary portion can comprise a through-hole for insertion of the threaded bolt (e.g. from the bottom side of the sole). However other means of securing ankle part to the sole are also conceivable.

According to a further embodiment, the front portion comprises a first plurality of markings and a second plurality of markings on the top side of the sole, wherein each marking of the first plurality defines a contour along which the front portion has to be cut to obtain a right sole having a certain size, and wherein each marking of the second plurality defines a contour along which the front portion has to be cut to obtain a left sole having a certain size. Alternatively, or in addition, the heel portion comprises a plurality of markings on the top side of the sole, wherein each marking defines a contour along which the heel portion has to be cut to obtain a sole having a certain size.

Advantageously these features of the sole according to the present invention allow one to produce a sole of a single size such as e.g. 300 mm length along the longitudinal axis which corresponds to Ell shoe size 46. Due to the above-described markings, this sole can be easily and cost-effectively shortened and therefore adapted to smaller feet by cutting the front portion and/or heel portion.

According to a particular embodiment of the present invention, the heel portion of the sole comprises at least one elongated recess on the bottom side of the sole. Further, according to an embodiment, the front portion of the sole comprises at least one elongated recess, particularly a plurality of elongated recesses extending along one another, on the bottom side of the sole.

According to a particular embodiment of the present invention, the heel portion comprises a recess formed into the heel portion on the bottom side, wherein the recess starts at a transition region between the intermediary portion and the heel portion and extends along the longitudinal axis to a rear edge of the heel portion, so that the rear edge comprises a depressed section and the heel portion of the sole comprises two opposing elongated ribs on either side of the recess that extend along the longitudinal axis. Particularly the recess comprises a width orthogonal to the longitudinal axis that is larger than a width of the respective rib orthogonal to the longitudinal axis. Advantageously, these recesses allow to finetune stiffness of the sole in the area of the heel portion in the longitudinal direction.

According to a further embodiment, the front portion comprises a first and a second recess formed into the front portion on the bottom side, wherein the first and the second recess both start at a transition region between the intermediary portion and the front portion and extend along the longitudinal axis to a front edge of the front portion, so that the front edge comprises two depressed sections and the front portion of the sole forms three elongated ribs that extend along the longitudinal axis with each two neighboring ribs being separated from one another by one of the recesses of the front portion. Advantageously, also here, the generated recesses allow to finetune stiffness of the sole in the area of the front portion in the longitudinal direction.

Furthermore, according to a preferred embodiment of the invention, the prosthetic foot comprises a heel part and a separate arch-shaped part, wherein the arch-shaped part forms the front portion, the intermediary portion, and an ankle portion, the ankle portion being integrally connected to the front portion via the intermediary portion, and wherein said heel part forms the heel portion, the heel part being configured to be releasably connected to the arch-shaped part at the intermediary portion.

Furthermore, according to a preferred embodiment of the invention, the heel part comprises a bottom side for contacting a ground upon walking on said ground and a top side facing away from said bottom side of the heel part, and/or wherein the archshaped part comprises a bottom side and a top side 15 facing away from said bottom side of the arch-shaped part.

Furthermore, according to a preferred embodiment of the invention, the top side of the heel part comprises a contact region configured to contact a contact region of the bottom side of the arch-shaped part in a form-fitting manner when the heel part is releasably connected to the arch-shaped part, i.e. the heel portion directly contacts the arch-shaped portion.

Furthermore, according to a preferred embodiment of the invention, the heel part is configured to be releasably connected to the arch-shaped part by means of at least a first connection element, the at least one first connection element extending through a hole formed in the heel part and into a further hole formed in the intermediary portion of the arch-shaped part.

Furthermore, according to a preferred embodiment of the invention, the at least one first connection element is a threaded bolt or a self-tapping screw.

Furthermore, according to a preferred embodiment of the invention, the arch-shaped part comprises at least a first protrusion formed on the top side 30 of the arch-shaped part, wherein said hole formed in the arch-shaped part extends from the bottom side of the arch-shaped part into said at least one first protrusion and eventually to a top side of the at least one first protrusion in case a connection element in the form of a threaded bolt is used.

Furthermore, according to a preferred embodiment of the invention, the bottom side of the heel part comprises at least a first recess formed in the heel part, wherein the hole of the heel part is arranged in the at least one first recess.

Furthermore, according to a preferred embodiment of the invention, the at least one first connection element comprises a head (and particularly a washer) arranged in the at least one first recess and is configured to be secured with a nut arranged on the top side of the at least one first protrusion. Furthermore, according to a preferred embodiment of the invention, the at least one first protrusion comprises two opposing lateral walls that continuously rise towards the top side along a longitudinal direction of the arch-shaped part.

Furthermore, according to a preferred embodiment of the invention, the bottom side of the heel part and/or the top side of the heel part comprises a curvature along a longitudinal axis of the heel part with an inflection point.

Furthermore, according to a preferred embodiment of the invention, the bottom-side of the arch-shaped part forms a convex surface, and/or wherein the top side of the archshaped part comprises a concave surface.

Furthermore, according to a preferred embodiment of the invention, the prosthetic foot comprises a connector for connecting the prosthetic foot to a component of a prosthesis, wherein the connector is configured to be releasably connected to an upper end section of the arch-shaped part, and wherein the connector is configured to be connected to said further component via a connecting member of the connector, which connecting member protrudes from a base of the connector.

Furthermore, according to a preferred embodiment of the invention, the end section of the arch-shaped part comprises a contact region configured to contact a contact region of the base of the connector in a form-fitting manner when the connector is releasably connected to the end section of the arch-shaped part, i.e. the connector directly contacts the end section of the arch-shaped part.

Furthermore, according to a preferred embodiment of the invention, the contact region of the base of the connector is configured to rest on a portion of the contact region of the end section, which portion comprises an edge of a face side of said end section.

Furthermore, according to a preferred embodiment of the invention, the connector is configured to be releasably connected to the end section of the arch-shaped part by means of at least a first connection element, the at least one first connection element extending through a hole formed in the end section of the arch-shaped part and into (or through) a further hole formed in the base of the connector.

Furthermore, according to a preferred embodiment of the invention, the base of the connector comprises a recess for receiving a portion of the connection element (e.g. a head or nut and particularly a washer of the connection element), the recess being arranged between two opposing tapered lateral wall portions of the base of the connector. Furthermore, according to a preferred embodiment of the invention, the base of the connector and the connecting member are each formed out of a metal (e.g. a steel alloy). Alternatively, the base of the connector is formed out of a plastic material (e.g. a polymer, wherein particularly the base of the connector is injection-molded) and wherein the connecting member is preferably formed out of a metal.

According to yet another aspect of the present invention, a method for producing a prosthetic foot, particularly according to the present invention, is disclosed, the method comprises the steps of: a) Providing a mold comprising a cavity defining the shape of the sole or the shape of a part of the prosthetic foot (e.g. said heel part or said arch-shaped part), b) Placing at least one fiber reinforced thermoplastic blank into the cavity of the mold, c) Closing the mold and compression molding of the at least one fiber reinforced thermoplastic blank residing in the cavity of the mold to form the sole or said part of the prosthetic foot.

According to a preferred embodiment, said part of the prosthetic foot is the heel part or the arch-shaped part. This also applies to all embodiments described further below when reference so said part of the prosthetic foot is made. Particularly, the method can be used to form both parts (e.g. in parallel or one after the other), wherein these parts (e.g. heel part and arch-shaped part) are each formed in a dedicated mold having a cavity that defines the shape of the respective part. However, the method may also be used to form only one of these parts, wherein a different method is used for the respective other part. Further, the parameters of the method stated below, such as temperatures, forces, orientation and placement of fibers and/or blanks etc. can be used for a monolithic sole as well as for said individual parts (such as heel part and arch-shaped part).

According to a preferred embodiment, step b) further comprises pre-heating the at least one fiber reinforced thermoplastic blank before placing the at least one fiber reinforced thermoplastic blank into the cavity of the mold, wherein preferably the at least one fiber reinforced thermoplastic blank is pre-heated to a temperature in the range from 150°C to 230°C.

Furthermore, in an embodiment, step b) further comprises placing a plurality of fiber reinforced thermoplastic blanks on top of one another into the cavity of the mold, namely, in an embodiment, preferably a first blank forming the bottom side of the sole, a second blank arranged on top of the first blank, the second blank being shorter than the first blank, and a third blank arranged on top of the second blank, the third blank being shorter than the second blank.

Furthermore, according to an embodiment, upon compression molding of the at least one fiber reinforced thermoplastic blank in the mold, a first plurality of markings and a second plurality of markings is formed in a front portion of the sole on a the top side of the sole, each marking of the first plurality defining a contour along which the front portion has to be cut to obtain a right sole having a certain size, and wherein each marking of the second plurality defining a contour along which the front portion has to be cut to obtain a left sole having a certain size.

Alternatively, or in addition, upon compression molding the at least one fiber reinforced thermoplastic blank in the mold, a plurality of markings is formed in the heel portion of the sole on the top side of the sole, each marking defining a contour along which the heel portion has to be cut to obtain a sole having a certain size.

Furthermore, according to a preferred embodiment, particularly in case the sole is formed out of a separate heel and arch-shaped part, upon compressing the at least one fiber reinforced thermoplastic blank in the cavity of the mold, at least one marking (or several such markings) is formed in said part of the prosthetic foot (e.g. in the heel part or in the arch-shaped part) on the top side of said part of the prosthetic foot, each marking defining a contour along which said part of the prosthetic foot has to be cut to obtain a sole having a certain size.

Furthermore, according to an embodiment, in step c), the mold is heated (e.g. before closing the mold), preferably to a temperature in the range from 50 °C to 70 °C, particularly to a temperature of about 65°C. Furthermore, in an embodiment, in step c), the at least one fiber reinforced thermoplastic blank is compressed with a force in the range from 40t to 90t after closing the mold, i.e. upon compression molding the sole out of the blank(s).

Furthermore, in an embodiment, the respective blank comprises a layer of randomly oriented fibers embedded in the thermoplastic. Further, in an embodiment, the respective blank comprises a plurality of fabric layers, the respective fabric layer comprising fibers embedded in the thermoplastic. Furthermore, according to an embodiment, the respective blank comprises first fibers extending along a longitudinal axis of the sole and second fibers extending perpendicular to the first fibers, the first and the second fibers being embedded in the thermoplastic (see also above). Particularly the ratio of the density of the first fibers with respect to the density of the second fibers in the respective blank can be larger or equal than 4: 1 in an embodiment. Other rations are also conceivable.

Furthermore, in an embodiment, the respective blank comprises at least a first and a second fabric layer, the first and the second fabric layer comprising fibers embedded in the thermoplastic, wherein the layer of randomly oriented fibers is arranged between the first and the second fabric layer.

Particularly, the respective fibers used in the various embodiments are glass fibers although the use of other fibers is also conceivable.

Regarding placing the respective thermoplastic blank into the respective mold, it is advantageous to layer and/or fold the preheated thermoplastic blanks so as to achieve a desired component volume in order to carry out the pressing process. In addition, the blanks usually have a predefined thickness while the thickness of the respective component can vary.

Finally, yet another aspect of the present invention relates to a sole, particularly for a prosthetic foot, the sole comprising a bottom side for contacting the ground upon walking, the sole further comprising a heel portion, an intermediary portion and a front portion, wherein the heel portion is connected to the front portion via said intermediary portion, wherein the sole is formed out of a fiber reinforced thermoplastic.

All embodiments and features described herein in conjunction with the sole of the prosthetic foot also apply to this sole and can therefore be used to further specify the sole according to the present invention.

Further features and advantages of the present inventions as well as embodiments of the present invention shall be described in the following with reference to the Figures, wherein

Fig. 1 shows a lateral view of a sole of a prosthetic foot according to the present invention,

Fig. 2 shows a perspective view of a top side of the sole,

Fig. 3 shows a plan view onto the top side of the sole,

Fig. 4 shows a plan view onto the bottom side of the sole,

Fig. 5 shows a perspective view of the bottom side of the sole,

Fig. 6 shows a further perspective view of the bottom side of the sole. Fig. 7 shows another perspective view of a top side of the sole,

Fig. 8 shows a front view of the sole onto the face side of the front portion,

Fig. 9 shows a rear view of the sole,

Fig. 10 shows a cross section of the sole showing a through-hole provided in the intermediary portion for connecting the angle part to the sole,

Fig. 11 shows an embodiment of the prosthetic foot comprising a sole as shown in Figs. 1 to 10 and an ankle part connected to the sole, e.g. via a threaded bolt, and

Fig. 12 illustrates a possible distribution/arrangement of fiber reinforced thermoplastic blanks in the cavity of the mold in order to form the front, intermediary and heel portion of the sole with a certain varying thickness, here an intermediary portion having a larger thickness than the front and heel portion of the sole.

Fig. 13 shows a mold for producing the sole according to the present invention using compression molding,

Fig. 14 illustrates a force acting on the sole upon a certain deflection of the sole stated on the x-axis,

Fig. 15 shows a lateral view of a further embodiment of prosthetic foot according to the present invention,

Fig. 16 shows a perspective view of a top side of the prosthetic foot of Fig. 15,

Fig. 17 shows a plan view onto the top side of the prosthetic foot of Fig. 15,

Fig. 18 shows a plan view onto the bottom side of the prosthetic foot of Fig. 15,

Fig. 19 shows a perspective view of the bottom side of the prosthetic foot of

Fig. 15,

Fig. 20 shows a further plan view onto the prosthetic foot of Fig. 15, and

Fig. 21 shows a further plan view onto the prosthetic foot of Fig. 15.

Fig. 1 shows in conjunction with Figs. 2 to 10 an embodiment of a sole 10 of a prosthetic foot 1 according to the present invention. According thereto the sole 10 comprises a bottom side 10a for contacting the ground upon walking. The sole can be divided into a heel portion 11 , an intermediary portion 12 and a front portion 13, wherein the heel portion 11 is integrally connected to the front portion 13 via said intermediary portion 12. This monolithic shape is preferably obtained by compression molding the sole from a fiber reinforced thermoplastic as described herein in multiple variants.

Particularly the sole 10 comprises fibers embedded into the thermoplastics, wherein such fibers can be randomly oriented, arranged in fabric layers or can be regularly oriented fibers (i.e., fibers extending along the longitudinal axis x of the sole and orthogonal thereto in the cross-direction y of the sole). Combinations of these different fiber arrangements are possible. Particularly, the fiber configurations described above can be used. The sole can be formed out of one or several cured blanks of the fiber reinforced thermoplastic (such as GMT or GMT-X or QTex, see also above) when compression molding the sole 10 in a mold 50 comprising e.g. a lower part 53 forming a cavity 51 and an upper part 52 forming a core that can be inserted into the cavity to form a hollow space corresponding the final shape of the sole 10.

In order to form the sole 10 one or several of the above-described blanks 100, 101 , 102 are pre-heated to a desired temperature (see above) and are then placed into the cavity 51. As an example, the blanks can comprise different sizes and can be stacked in the cavity 51 of the mold as illustrated in Fig. 12. In this case a sole 10 can be formed via compression molding in the mold 50 that comprises an intermediary portion 12 that comprises a thickness T’ that is larger than the thicknesses T, T” of the heel and front portions 11 , 13 (cf. Fig. 1).

To form the sole 10, the pre-heated blank(s) 100, 101 , 102 are compressed in the mold 10 by means of the two parts 52, 53, wherein the mold is heated to a pre-defined temperature (see above). The force of compression can lie within the range from 40 tons to 90 tons.

The final sole 10 can be ejected from the cavity 51 by pressurizing the nozzles 55.

Preferably, the thermoplastic is polypropylene and the fibers embedded therein are glass fibers in particular. Other thermoplastic and fiber materials are also conceivable.

According to an embodiment (cf. e.g. Fig. 1), the intermediary portion 12 comprises a concave curvature on the bottom side 10a and a convex curvature on the top side 10b of the sole 10. As indicated in Fig. 11 , the intermediary portion 12 is configured to be connected to an ankle part 20 of the prosthetic foot 1. Particularly, the ankle part 20 can be connected to the intermediary portion 12 via at least one threaded bolt 21 that extends through through-hole 10c (cf. e.g. Fig. 2) formed in the intermediary portion 12 and can be secured with a nut 22. Particularly, the threaded bolt 20 can be inserted into the through-hole 10c from the bottom side 10a of the sole 10.

Preferably, according to an embodiment, the sole comprises markings 110, 130, 131 on the top side 10b along which the respective portion 11 , 13 can be cut to obtain a sole 10 of desired length and orientation (left or right sole). Advantageously, the markings can be formed as depressions upon compression molding which also simplifies the cutting process using simple cutting tools.

As particularly shown in Fig. 4 to 6 and 8 to 9, the bottom side 10a of the sole can comprise a structure of recesses 30, 40, 41 and corresponding ribs 31 , 32, 42, 43, 44.

Particularly, the heel portion 11 can comprise an elongated recess 30 formed into the heel portion 11 on the bottom side 10a, which recess extends along the longitudinal axis x of the sole towards a rear edge 11 a of the heel portion 11. Particularly, the rear edge 11a can comprises a depressed section 11b owing to the recess 30. Due to the recess 30 the heel portion 11 of the sole 10 comprises two opposing elongated ribs 31 , 32 on either side of the recess 30 that extend along the longitudinal axis x and stiffen the heel portion in a defined manner.

Furthermore, the front portion 13 can comprise one or several recesses, too. Particularly, the front portion 13 of the sole 10 can comprise a first and a second elongated recess 40, 41 formed into the front portion 13 on the bottom side 10a of the sole 10, wherein the first and the second recess 40, 41 extend along the longitudinal axis x, too, namely towards a front edge 13a of the front portion 13. Particularly, owing to the recesses 40, 41 , the front edge 13a can comprise two depressed sections 13b. Due to recesses 40, 41 , the front portion 13 of the sole 10 forms three elongated ribs 42, 43, 44 that extend along the longitudinal axis x with each two neighboring ribs 42, 43; 43, 44 being separated from one another by one of the recesses 40, 41 of the front portion 13. Due to these ribs 42, 43, 44, the front portion 13 comprises a desired stiffness.

Particularly, as illustrated in Fig. 14, using a fiber reinforced thermoplastic, the characteristics of the sole 10 can be precisely tuned by varying the overall thickness of the sole 10, particularly the thickness in the individual regions 11 , 12, 13 of the sole.

Particularly, D3 denotes the thickest sole comprising a thickness of about 8-12 mm, while D1 denotes the thinnest sole comprising a thickness of about 6-10 mm. Further, “Front” refers to the front portion 13 being deflected while “Heel” refers to the heel portion 11 being deflected. As can be inferred from Fig. 14, the sole 10 can be tuned in a manner that a desirable linear force-deflection relationship can be established.

According to a further embodiment shown in Figs. 15 to 21 , the prosthetic foot 1 comprises a heel part 60 and a separate arch-shaped part 70 that can be connected to one another in a releasable fashion (particularly, in the embodiments described above, the sole 10 can comprise integrally connected portions 11 , 12, 13). Here, as shown in Figs. 15 to 21 the arch-shaped part 70 forms the front portion 13, the intermediary portion 12 (or at least a portion thereof), and an ankle portion 14 of the sole 10, the ankle portion 14 being integrally connected to the front portion 13 via the intermediary portion 12 in particular. Further, the separate heel part 60 forms the heel portion 11 of the sole 10, the heel part 60 being configured to be releasably connected to the arch-shaped part 70, namely preferably at the intermediary portion 12.

The heel part 60 comprises a bottom side 60a that forms part of the bottom side 10 of the overall sole 10 and serves for contacting a ground upon walking on said ground. The top side 60b of the heel part 60 faces away from said bottom side 60a and forms a portion of the top side 10b of the sole 10 as indicated e.g. in Fig. 15.

Furthermore, the arch-shaped part 70 comprises a bottom side 70a and a top side 70b facing away from said bottom side 70a of the arch-shaped part 70. As indicated in Fig. 15, the bottom side 70a forms a portion of the bottom side 10a of the sole 10, together with the bottom side 60a of the heel part 60.

As indicated in Fig. 15, the top side 60b of the heel part 60 forms a contact region 60c configured to contact a contact region 70c of the bottom side 70a of the arch-shaped part 70 in a preferably form-fitting manner when the heel part 60 is releasably connected to the arch-shaped part 70. Thus, the heel part 60 can directly contact the arch-shaped part 70 over a relatively large area.

As can be seen from the Figs. 15 to 21 , the heel part 60 is configured to be releasably connected to the arch-shaped part 70 by means of at least a first connection element 90. Preferably, two such connections elements 90, i.e. a first and a second connection element 90, are used. The connection elements 90 can be threaded bolts 90. Alternatively, each connection element 90 can also be a self-tapping screw instead of a threaded bolt. In this case the foot 1 may preferably comprise one, two, three or four such self-tapping screw(s) as connection element(s).

Particularly, the respective connection element 90 (e.g. bolt or self-tapping screw) extends through a hole 91 formed in the heel part 60 and into a further hole 92 formed in the intermediary portion 12 of the arch-shaped part 70. In case of a bolt 90, the connection element 90 / further hole 92 extends completely through the arch-shaped part 70 to allow securing the respective bolt 90 with a nut 94. In case the respective connection element 90 is a self-tapping screw, the screw cuts a thread into the archshaped part 70 and the corresponding further hole 92 can be a blind hole. The screw is then directly anchored in the arch-shaped part 70.

Preferably, as shown in Figs. 15 and 16, the arch-shaped part 70 comprises a protrusion 71 per connection element 90. The respective protrusion 71 is formed on the top side 70b of the arch-shaped part 70 (e.g. in the intermediary region 12), wherein the respective hole 92 formed in the arch-shaped part 70 for the respective connection element 90 extends from the bottom side 70a of the arch-shaped part 70 into the respective protrusion 71. In case of a bolt 90, the respective hole 92 is a through-hole that extends through the protrusion 71 so that the bolt 90 can be fastened on the top side 71b of the protrusion 71 by means of a nut 94. In case of one or several connection elements 90 in form of self-tapping screws, the respective hole 92 can be a blind hole (see also above).

Furthermore, as shown in Fig. 15, the respective protrusion preferably comprises two opposing lateral walls 72 that gradually rise from the surface of the top side 70b of the arch-shaped part 70 towards a top side 71 b of the respective protrusion 71 . Along the longitudinal direction of the arch-shaped part 70, the respective protrusion 71 thus comprises a continuously increasing / decreasing thickness as shown e.g. in Fig. 15.

On the side facing away from the protrusion(s) 71 , the bottom side 60a of the heel part 60 comprises at least a first recess 61 formed in the heel part 60, wherein the respective hole 91 formed in the heel part 60 for receiving the respective connection element 90 is arranged in a recess 61 .

This allows to countersink the heads 93 of the connection elements 90 in the respective recess 61 so that the risk of having the heads 93 touch the ground upon walking is reduced.

Furthermore, as e.g. indicated in Fig. 15, the bottom side 60a of the heel part 60 and/or the top side 60b of the heel part 60 can comprises a curvature along a longitudinal axis of the heel part 60 comprising an inflection point which supports flexing of the heel part 60 upon walking.

Further, as particularly shown in Fig. 15, the bottom side 70a of the arch-shaped part 70 forms a convex surface. Similarly, the top side 70b of the arch-shaped part 70 forms a concave surface, apart from said protrusions 71. Due to the curved shape of the arch-shaped part 70 stability and controlled flexing of the arch-shaped part is achieved.

In order to connect the prosthetic foot 1 to further components of a prosthesis such as a lower leg, the prosthetic foot comprises a connector 80 that is configured to couple the prosthetic foot 1 to such a further component of a prosthesis. Particularly, the connector 80 is configured to be releasably connected to an upper end section 73 of the arch-shaped part 70. Particularly, the connector 80 comprises a connecting member 81 projecting from a base 83 of the connector 80. The connecting member 81 can be configured to allow coupling of said further component to the prosthetic foot with an adjustable angle. Such connecting members 81 are known in the state of the art.

Preferably, as shown e.g. in Fig. 15, the end section 73 of the arch-shaped part 70 comprises a contact region 73d configured to contact a contact region 83c of the base 83 of the connector 80 in a form-fitting manner when the connector 80 / base 83 is releasably connected to the end section 73 of the arch-shaped part 70. Here, base 83 of the connector 80 directly contacts the end section 73 of the arch-shaped part 70.

Preferably, the contact region 83c of the base 83 of the connector 80 rests on a portion of the contact region 73d that comprises an edge of an upper face side 73a of said end section 73.

Furthermore, also the connector 80 is configured to be releasably connected to the end section 73 of the arch-shaped part 70 by means of one or several connection elements 95, wherein the respective connection element 95 extends through a hole 96 formed in the end section 73 of the arch-shaped part 70 and into and/or through a further hole 97 formed in the base 83 of the connector 80.

Also here, the respective connection element 95 can be a threaded bolt 95 with head 98, wherein the bolt 95 is secured with a nut 99. Here, the respective further hole 97 is formed as a through-hole. Alternatively, as described above, one or several selftapping screws can be used as connection elements 95. Here the further holes 97 can be formed as blind holes 97 formed by the respective screw.

Furthermore, as shown e.g. in Fig. 16 in conjunction with Fig. 21 , the base 83 of the connector 80 comprises a recess 82 for receiving a portion of the connection elements 95 (e.g. the respective head 98, or alternatively the respective nut 99 of the connection element 95). Particularly, the recess 82 of the base 83 is arranged between two opposing tapered lateral wall portions 84 of the base 83 of the connector 80. This ensures good accessibility of the nuts 99, but also prevents objects in the vicinity of the foot 1 from becoming entangled to the protruding nut(s) 99.

The base 83 of the connector 80 and the connecting member 81 can each be formed out of a metal (such as a steel alloy). Alternatively, the base 83 of the connector 80 can be formed of a plastic material (e.g. a polymer), particularly by way of injection molding. Preferably, in case of a plastic base 80, the connecting member 81 is formed preferably formed out of a metal such as a steel alloy.

Furthermore, the connection elements 90, 95 are preferably formed out of a metal, particularly a steel alloy.

Preferably, the protrusions 71 are integrally formed with the arch-shaped part 70.

Also in case of the embodiment shown in Figs. 15 to 21 , a monolithic shape of the respective part 60, 70 is preferably obtained by compression molding the respective part as described above from a fiber reinforced thermoplastic.

Particularly the, the respective part 60, 70 forming part of the overall sole 10, can comprise fibers embedded into the thermoplastics, wherein such fibers can be randomly oriented, arranged in fabric layers or can be regularly oriented fibers (i.e., fibers extending along the longitudinal axis of the respective part 60, 70 and orthogonal thereto in the cross-direction y of the respective part 60, 70). Combinations of these different fiber arrangements are possible. Particularly, the fiber configurations described above can be used. The respective part 60, 70 (apart from components formed out of a metal such as the connection elements 90, 95 and e.g. the connector 80) can be formed out of one or several cured blanks of the fiber reinforced thermoplastic (such as GMT or GMT-X or QTex, see also above) by way of compression molding in a mold corresponding to the shape of the respective part 60, 70.

*****

Claims

1. A prosthetic foot (1), comprising: a sole (10) comprising a bottom side (10a) for contacting the ground upon walking, the sole (10) further comprising a heel portion (11), an intermediary portion (12) and a front portion (13), wherein the heel portion (11) is connected to the front portion (13) via said intermediary portion (12), wherein the sole (10) is formed out of a fiber reinforced thermoplastic.

2. The prosthetic foot according to claim 1 , wherein the fiber reinforced thermoplastic comprises a plurality of layers comprising randomly oriented fibers embedded in the thermoplastic.

3. The prosthetic foot according to claim 1 or 2, wherein the fiber reinforced thermoplastic comprises a plurality of fabric layers comprising fibers embedded in the thermoplastic.

4. The prosthetic foot according to one of the preceding claims, wherein the fiber reinforced thermoplastic comprises first fibers extending along a longitudinal axis of the sole and second fibers extending perpendicular to the first fibers, the first and the second fibers being embedded in the thermoplastic.

5. The prosthetic foot according to one of the preceding claims, wherein the thermoplastic is formed by or comprises polypropylene.

6. The prosthetic foot according to one of the preceding claims, wherein the randomly oriented fibers and/or said fibers of the fabric layers are glass fibers.

7. The prosthetic foot according to one of the preceding claims, wherein the heel portion (11), the intermediary portion (12) and the front portion (13) each comprise a thickness (T, T’, T”) orthogonal to the bottom side (10a), the thickness (T’) of the intermediary portion (12) being larger than or equal to the thickness (T”) of the front portion (13) and the thickness (T) of the heel portion (11).

8. The prosthetic foot according to one of the preceding claims, wherein the intermediary portion (12) comprises a concave curvature on the bottom side (10a) of the sole (10).

9. The prosthetic foot according to one of the preceding claims, wherein the sole (10) comprises a top side (10b) facing away from the bottom side (10a). The prosthetic foot according to claim 9, wherein the intermediary portion (12) comprises a convex curvature on the top side (10b). The prosthetic foot according to one of the preceding claims, wherein the intermediary portion (12) is configured to be connected to an ankle part (20) of the prosthetic foot (1). The prosthetic foot according to one of the preceding claims, wherein the prosthetic foot (1) comprises an ankle part (20), the ankle part (20) being connected to the intermediary portion (12) via at least one threaded bolt (21) being secured with a nut (22). The prosthetic foot according to one of the preceding claims, wherein the front portion (13) comprises a first plurality of markings (130) and a second plurality of markings (131) on the top side (10b) of the sole (10), wherein each marking (130) of the first plurality defines a contour along which the front portion (13) has to be cut to obtain a right sole having a certain size, and wherein each marking (131) of the second plurality defines a contour along which the front portion (13) has to be cut to obtain a left sole having a certain size. The prosthetic foot according to one of the preceding claims, wherein the heel portion (11) comprises a plurality of markings (110) on the top side (10b) of the sole (10), wherein each marking (110) defines a contour along which the heel portion (11) has to be cut to obtain a sole having a certain size. The prosthetic foot according to one of the preceding claims, wherein the sole (10) extends along a longitudinal axis (x). The prosthetic foot according to claim 15, wherein the heel portion (11) comprises a recess (30) formed into the heel portion (11) on the bottom side (10a), wherein the recess (30) starts at a transition region between the intermediary portion (12) and the heel portion (11) and extends along the longitudinal axis (x) to a rear edge (11a) of the heel portion, so that the rear edge (11a) comprises a depressed section (11b) and the heel portion (11) of the sole (10) comprises two opposing elongated ribs (31 , 32) on either side of the recess (30) that extend along the longitudinal axis (x). The prosthetic foot according to claim 15 or 16, wherein the front portion (13) comprises a first and a second recess (40, 41) formed into the front portion (13) on the bottom side (10a) of the sole (10), wherein the first and the second recess (40, 41) both start at a transition region between the intermediary portion (12) and the front portion (13) and extend along the longitudinal axis (x) to a front edge (13a) of the front portion (13), so that the front edge (13a) comprises two depressed sections (13b) and the front portion (13) of the sole (10) forms three elongated ribs (42, 43, 44) that extend along the longitudinal axis (x).

18. The prosthetic foot according to one of the preceding claims, wherein the prosthetic foot comprises a heel part (60) and a separate arch-shaped part (70), wherein the arch-shaped part (70) forms the front portion (13), the intermediary portion (12), and an ankle portion (14), the ankle portion (14) being integrally connected to the front portion (13) via the intermediary portion (12), and wherein said heel part (60) forms the heel portion (11), the heel part (60) being configured to be releasably connected to the arch-shaped part (70) at the intermediary portion (12).

19. The prosthetic foot according to claim 18, wherein the heel part (60) comprises a bottom side (60a) and a top side (60b) facing away from said bottom side (60a) of the heel part (60), and/or wherein the arch-shaped part (70) comprises a bottom side (70a) and a top side (70b) facing away from said bottom side (70a) of the arch-shaped part (70).

20. The prosthetic foot according to claim 19, wherein the top side (60b) of the heel part (60) comprises a contact region (60c) configured to contact a contact region (70c) of the bottom side (70a) of the arch-shaped part (70) in a form-fitting manner when the heel part (60) is releasably connected to the arch-shaped part (70).

21 . The prosthetic foot according to one of the claims 18 to 20, wherein the heel part (60) is configured to be releasably connected to the arch-shaped part (70) by means of at least a first connection element (90), the at least one first connection element (90) extending through a hole (91) formed in the heel part (60) and extending into a further hole (92) formed in the arch-shaped part (70).

22. The prosthetic foot according to claim 21 , wherein the at least one first connection element (90) is a threaded bolt (90) or a self-tapping screw.

23. The prosthetic foot according to one of the claims 19 to 22, wherein the archshaped part (70) comprises at least a first protrusion (71) formed on the top side (70b) of the arch-shaped part (70), the at least one first protrusion comprising a top side (71b), wherein said hole (92) formed in the arch-shaped part (70) extends from the bottom side (70a) of the arch-shaped part (70) into said at least one first protrusion (71). 21

24. The prosthetic foot according to one of the claims 21 to 23, wherein the bottom side (60a) of the heel part (60) comprises at least a first recess (61) formed in the heel part (60), wherein the hole (91) of the heel part (60) is arranged in the at least one first recess (61).

25. The prosthetic foot according to one of the claims 21 to 24, wherein the at least one first connection element (90) comprises a head (93) arranged in the at least one first recess (61) and is configured to be secured with a nut (94) arranged on the top side (71 b) of the at least one first protrusion (71).

26. The prosthetic foot according to one of the claims 23 to 24, wherein the at least one first protrusion (71) comprises two opposing lateral walls (72) that continuously rise towards the top side (71 b) of the at least one first protrusion along a longitudinal direction of the arch-shaped part (70).

27. The prosthetic foot according to one of the claims 18 to 26, wherein the bottom side (60a) of the heel part (60) and/or the top side (60b) of the heel part (60) comprises a curvature along a longitudinal axis of the heel part (60) with an inflection point.

28. The prosthetic foot according to one of the claims 18 to 27 wherein the bottomside (70a) of the arch-shaped part (70) forms a convex surface, and/or wherein the top side (70b) of the arch-shaped part (70) forms a concave surface.

29. The prosthetic foot according to one of the claims 18 to 28, wherein the prosthetic foot comprises a connector (80) for connecting the prosthetic foot to a component of a prosthesis, wherein the connector (80) is configured to be releasably connected to an end section (73) of the arch-shaped part (70), and wherein the connector (80) is configured to be connected to said further component via a connecting member (81) of the connector (80), which connecting member (81) protrudes from a base (83) of the connector (80).

30. The prosthetic foot according to claim 29, wherein the end section (73) of the archshaped part (70) comprises a contact region (73d) configured to contact a contact region (83c) of the base (83) of the connector (80) in a form-fitting manner when the connector (80) is releasably connected to the end section (73) of the archshaped part (70).

31. The prosthetic foot according to claim 30, wherein the contact region (83c) of the base (83) of the connector (80) is configured to rest on a portion of the contact 22 region (73d) of the end section (73), which portion comprises an edge of a face side (73a) of said end section (73). The prosthetic foot according to one of the claims 29 to 31 , wherein the connector (80) is configured to be releasably connected to the end section (73) of the archshaped part (70) by means of at least a first connection element (95), the at least one first connection element (95) extending through a hole (96) formed in the end section (73) of the arch-shaped part (70) and extending into a further hole (97) formed in the base (83) of the connector (80). The prosthetic foot according to one of the claims 29 to 32, wherein the base (83) of the connector (80) comprises a recess (82) for receiving a portion of the at least one first connection element (95), the recess (82) being arranged between two opposing tapered lateral wall portions (84) of the base (83) of the connector (80). The prosthetic foot according to one of the claims 29 to 33, wherein the base (83) of the connector (80) and the connecting member (81) are each formed out of a metal; or wherein the base (83) of the connector (80) is formed out of a plastic material, and wherein the connecting member (81) is formed out of a metal. A method for producing a prosthetic foot, particularly according to one of the preceding claims, the method comprises the steps of: a) Providing a mold (50) comprising a cavity (51) corresponding the shape of the sole (10) or corresponding to the shape of a part of the prosthetic foot (60; 70), b) Placing at least one fiber reinforced thermoplastic blank (100, 101 , 102) into the cavity (51) of the mold (50), c) Closing the mold (50) and compressing the at least one fiber reinforced thermoplastic blank (100, 101 , 102) residing in the cavity (51) of the mold (50) to form the sole or said part of the prosthetic foot (60; 70). The method according to claim 35, wherein step b) further comprises pre-heating the at least one fiber reinforced thermoplastic blank (101 , 102, 103) before placing the at least one fiber reinforced thermoplastic blank into the cavity (51) of the mold (50), wherein preferably the at least one fiber reinforced thermoplastic blank (100, 101 , 102) is pre-heated to a temperature in the range from 150°C to 230°C. The method according to claim 35 or 36, wherein step b) comprises placing a plurality of fiber reinforced thermoplastic blanks (100, 101 , 102) on top of one another into the cavity (51) of the mold (50), namely preferably a first blank (100) 23 forming the bottom side (10a) of the sole (10), a second blank (101) arranged on top of the first blank (100), the second blank (101) being shorter than the first blank (100), and a third blank (102) arranged on top of the second blank (101), the third blank (102) being shorter than the second blank (101).

38. The method according to one of the claims 35 to 37, wherein upon compressing the at least one fiber reinforced thermoplastic blank (100, 101 , 102) in the cavity (51) of the mold (50), a first plurality of markings (130) and a second plurality of markings (131) is formed in a front portion (13) of the sole (10) on a the top side (10a) of the sole (10), each marking (130) of the first plurality defining a contour along which the front portion has to be cut to obtain a right sole having a certain size, and wherein each marking (131) of the second plurality defining a contour along which the front portion has to be cut to obtain a left sole having a certain size, and/or wherein upon compressing the at least one fiber reinforced thermoplastic blank (100, 101 , 102) in the cavity (51) of the mold (50), a plurality of marking (110) is formed in the heel portion (11) of the sole (10) on the top side (10b) of the sole (10), each marking (110) defining a contour along which the heel portion (11) has to be cut to obtain a sole having a certain size, and/or wherein upon compressing the at least one fiber reinforced thermoplastic blank in the cavity of the mold, at least one marking (132) is formed in said part of the prosthetic foot (60, 70) on the top side (60b, 70b) of said part of the prosthetic foot (60, 70), each marking (132) defining a contour along which said part of the prosthetic foot (60, 70) has to be cut to obtain a sole having a certain size.

39. The method according to one of the claims 35 to 38, wherein in step c) the mold (50) is heated to a temperature in the range from 50 °C to 70 °C, particularly 65°C, and/or wherein in step c) the at least one fiber reinforced thermoplastic blank is compressed with a force in the range from 40t to 90t.

40. The method according to one of the claims 35 to 39, wherein the respective blank (100, 101 , 102) comprises a layer of randomly oriented fibers embedded in the thermoplastic.

41. The method according to one of the claims 35 to 40, wherein the respective blank (100, 101 , 102) comprises a plurality of fabric layers, the respective fabric layer comprising fibers embedded in the thermoplastic.

42. The method according to one of the claims 35 to 41 , wherein the respective blank (100, 101 , 102) comprises first fibers extending along a longitudinal axis (x) of the 24 sole and second fibers extending perpendicular to the first fibers, the first and the second fibers being embedded in the thermoplastic. The method according to claim 40 or 41 , wherein the respective blank (100, 101 , 102) comprises at least a first and a second fabric layer, the first and the second fabric layer comprising fibers embedded in the thermoplastic, wherein the layer of randomly oriented fibers is arranged between the first and the second fabric layer.