Prosthetic foot and method for manufacturing such a foot

Abstract

The invention relates to a prosthetic foot (P) of a user, and to a method for manufacturing such a foot. The foot comprises a foot prosthesis (21) with a so-called dynamic-return leaf spring, having a compression space and an end portion (33) pointing towards the top for connection with the leg of the user. The prosthetic foot comprises a shell arranged to cover the prosthesis, having a sole part (2) made of a flexible elastomer or plastic material and an upper part (3) which is obtained by injection moulding of expanded EVA (expanded IMEVA) and provided with a through-slot for contiguous friction (or contact) with the upward-pointing end part (33) extending through the slot, and an elastic plugging wedge filling the compression space, the sole part (2) and the upper part (3) being bonded together along their peripheral portions.

Description

Prosthetic foot and manufacturing process of such a foot

[0001] The present invention relates to a prosthetic foot comprising a prosthetic body or foot prosthesis equipped with an external covering or envelope.

[0002] It also relates to a manufacturing process for such a prosthetic foot.

[0003] It finds a particularly important, although not exclusive, application in the field of prosthetic feet with dynamic return intended for the active population of amputee patients.

[0004] A prosthetic foot is a medical device designed to replace a missing foot, aiming to restore the function of the natural foot. It allows the amputee to regain mobility and an improved quality of life.

[0005] It therefore includes a prosthetic body formed by a rigid part, called an "insert", which connects to a fixing part located on the user's leg, and a foot-shaped shell, more or less realistic, but allowing the attachment of a shoe.

[0006] There are currently several types of prosthetic feet.

[0007] The first type is called passive, or SACH (Solid Ankle Cushion Heel), and is reserved for people with limited walking activity. An example is the Otto Bock 1WR95 prosthetic foot from the German company Otto Bock. This foot has a rigid solid core, to which a connecting element attaches on its upper wooden outer part to connect with the rest of the patient's prosthesis. It is waterproof and sandproof, but offers very limited functionality, incompatible with the activity level of a highly active patient with K3 or K4 mobility. K mobility levels (K1, ...K3 or K4) are mobility standards used by the American CMS (Centers for Medicare & Medicaid Services).

[0008] This type of foot is generally used only occasionally for specific activities that may involve contact with water or sand, but the patient must then change to a prosthesis better suited to their daily activity level. This type of foot is made of materials that make it very slippery on wet surfaces (particularly polyurethane), which presents a significant risk of falls and injuries for the user.

[0009] A similar type of foot is the GERY foot from the French company PROTEOR. It consists of an EVA (Ethylene-Vinyl Acetate) core into which an anchor-shaped element is inserted at the top, connecting it to the rest of the patient's prosthesis. However, its considerable flexibility makes it unsuitable for patients with moderate to high activity levels, as it is only indicated for patients with low activity levels.

[0010] These foot prostheses have in common that they cannot integrate a prosthetic energy-returning blade into their manufacture and therefore offer reduced functionality in terms of walking comfort or energy return, limiting them to patients with low activity (category K1).

[0011] There is a second type, similar to the SACH foot but allowing for the integration of a composite or plastic blade. The blade is inserted into a mold by casting, usually with liquid polyurethane, prior to the foot's molding. Examples include the IMPULSE feet from the American company Ohio WillowWood, which offer better functionality than simple SACH feet, but whose functional characteristics still fall short of high-performance prosthetic feet such as energy-returning feet and cannot be considered a sufficient replacement for most very active users. Due to the nature of polyurethane, an open-cell material prone to degradation by hydrolysis upon prolonged contact with moisture and water, it is necessary to choose a relatively rigid polyurethane compound, which is unfavorable for the blade's function.The functional capabilities of such feet are therefore limited, preventing active patients from receiving a prosthetic foot that meets their needs in terms of walking comfort and energy return. Furthermore, these polyurethane feet are very slippery on wet surfaces, creating a significant risk of falls and injuries, for example, on wet tiles, shower floors, or bathtubs.

[0012] The third type of prosthetic foot known from the previous era is the so-called active or dynamic-return foot. It is designed for amputees who engage in regular or intensive walking, generally classified according to the patient mobility classification system as level 3 or 4, K3 or K4. It consists of a prosthesis made of a blade-shaped insert that is elastically deformable and made of composite material, carbon fiber, metal, or plastic. This insert extends the length of the foot and connects at its upper end to a component that attaches to the leg. The blade, the length of which is adapted to the patient, moves in different directions of flexion and provides a spring-like effect that plays a significant role in walking by offering comfort and energy return.

[0013] To ensure an aesthetically pleasing result and allow for shoe attachment, this type of prosthesis includes a hollow foot shell, generally made of polyurethane, with an opening that allows it to be slipped over the lower part of the blade, much like a shoe on a foot. The blade is secured inside the shell, for example, by a lug integrated into the shell's shape or by straps. To ensure it remains in place around the blade, one or more straps are used. The hollow shell thus surrounds only the lower part of the blade, allowing for blade movement and maintaining its spring-like effect, which is essential for optimal patient gait.

[0014] The major drawback of this type of prosthetic foot is that it is hollow and requires constant maintenance to remove impurities (sand, water, etc.) that accumulate between the blade and the shell through the opening in the shell. Therefore, it is not suitable for a variety of activities, particularly swimming or walking on a beach, as this could damage the blade.

[0015] The objective of the present invention is to offer a foot with the functionalities of so-called energy-return prosthetic feet for active to very active patients, meeting the requirements of practice better than those previously known, in particular in that it requires little or no maintenance, in that it allows very versatile use suitable for walking and including swimming in fresh or salt water, walking in the sand, and this for active users, without risk to the integrity of the blade, in that it is of lighter design and advantageously more anti-slip to reduce the risk of falls or injuries on wet ground, in that it is made of a material substantially insensitive to moisture or water, and in that it can be made in many versions of energy-return prosthetic blades.

[0016] Another objective of the invention is to overcome the disadvantages of the prior art and to improve the comfort and walking abilities of the user of the prosthetic foot.

[0017] Another objective of the invention is to provide a prosthetic foot with good abrasion resistance and / or to be anti-slip.

[0018] Another objective of the invention is to propose a method for manufacturing such a prosthetic foot by means of molding and gluing operations that are more efficient and controlled than those of the prior art.

[0019] The invention is based on the idea of ​​obtaining a prosthetic foot using a dynamic return foot prosthesis comprising a closed and non-removable cover or casing of the foot prosthesis, the latter being in the form of a blade of determined characteristics, by bonding and from at least two casing parts, including an upper part obtained by injection molding of EVA (Ethylene-Vinyl Acetate) or (IMEVA) (Anglo-Saxon initials for "Injected Moulded Ethylene Vinyl Acetate") in expanded form, and a lower part or sole.

[0020] Expanded IMEVA is obtained using a known process by heating and swelling EVA material, creating a closed-cell structure that gives it cushioning and resilience properties. Advantageously, the lower part, or sole, is made of a more resistant material than expanded IMEVA, for example, CMEVA (Compressed Moulded EVA).

[0021] EVA is a material commonly used in the manufacture of adhesives, stretch films, and flexible gloves. While it offers good flexibility and handling properties, it is unsuitable and difficult to use in injection molding (IMEVA) in its lightweight expanded foam form because it expands immediately and is difficult to control during demolding. The present invention has addressed this drawback and found a way to overcome it.

[0022] Expanded EVA, on the other hand, has a foam structure made of ethylene vinyl acetate copolymer composed of billions of extremely thin, closed cells that are impermeable to fluids and trap air completely. This structure is the antithesis of that of an integrated network of open cells obtained, for example, by 3D printing, as described in US patent 2021 / 177628, which deals with a prosthetic foot comprising a mesh-like shell threaded onto the prosthetic blade in a non-airtight manner.

[0023] The blade, for example, is a profiled and curved blade to imitate the natural movements of the foot and ankle. It comprises a body having a median section of the sole free on one side (the heel side) and connected on the other side (the toe side) to a section of the top of the foot, for example substantially L-shaped or C-shaped, comprising a lower spring extending above and progressively away from the median section of the sole and being extended (on the heel side) by an end part, directed upwards (inclined or curved), for example vertical or substantially vertical, connecting to a fitting worn by the user's leg.

[0024] To this end, the invention proposes in particular a prosthetic foot for a user comprising a spring-bladed foot prosthesis with dynamic return, said blade providing a compression space between a part of the blade, called the bottom blade, and a part of the blade, called the top blade, extended by an upward-directed end portion for connection with the user's leg, and an envelope arranged to cover said prosthesis, characterized in that the envelope comprises a sole part made of elastomer or flexible plastic material cooperating with the bottom blade portion and an upper part obtained by injection molding of expanded EVA (expanded IMVEA) cooperating with the top blade portion and being provided with a friction (or contact) passage slot for the exit of the upward-directed end portion,in that it comprises an elastic sealing wedge filling said compression space and in that the sole part and the upper part are bonded together at their peripheral edges.

[0025] It is understood that the sole portion is essentially flat. It thus has, for example, a flattened disc shape whose outline corresponds to the underside of a foot, for example, with a thickness between 3 mm and 1 cm. Advantageously, it includes an upper recess designed to receive the lower part of the foot's blade, which is at least partially embedded in said recess.

[0026] An elastic filling shim is a shim with a reduced Shore hardness that can plastically deform to adapt to and allow the spring effect of the blade, without causing air displacement and / or requiring air evacuation or inhalation. For example, it is a shim of a specific shape corresponding to the empty space or compression area of ​​the prosthesis. It is, for instance, made of expanded IMVEA with a hardness equal to or less than that of the upper part.

[0027] Shore hardness is measured with a durometer in a way known in itself, for example by reference to the so-called Shore A scale. The hardness of the upper part is for example between 40 and 80 on this scale, and that of the wedge between 20 and 70.

[0028] More specifically, this EVA or damping filler wedge or plug is sized and arranged to be placed between the upper face of an end section of the bottom foot blade and the lower face of the top foot blade section located directly above, i.e. extending above and away from said bottom foot end section.

[0029] Advantageously, the upper face of the sole part is glued to the underside blade part of the foot.

[0030] In an advantageous embodiment, the inner face of the upper part of the cover is glued to the upper face of the foot top section and the gap for the contact friction passage is glued to the upward-facing end part of the connection with the user's leg.

[0031] In advantageous embodiments, one or both of the following arrangements are also made: the peripheral part of the upper face of the sole is designed to fit together and be bonded to the peripheral part of the lower face of said upper part; the sole is obtained by compression molding of EVA (CMVEA), previously expanded or not; the peripheral parts of the upper face of the sole, on the one hand, and of the lower face of the upper part, on the other hand, comprise, for the former, a projecting edge and, for the latter, a corresponding recess arranged to cooperate with play and adapt to each other before bonding. The projecting edge is, for example, on the sole and the recess on the upper part. But it can be the other way around. This allows for excellent adaptive interlocking, facilitating the absorption of variations during the injection / expansion of the expanded IMVEA.The protruding edge and the recess, for example, have a complementary beveled shape. Such a fit with play allows for excellent fastening of the two parts together while providing an aesthetically pleasing exterior appearance, as the joint between the two becomes barely noticeable or visible once the parts are glued together.Furthermore, we will be able to achieve an even stronger bond thanks to the guarantee that such arrangements provide, allowing the parts to be applied to each other over the largest possible contact area; alternatively, the protruding edge forms a rounded peripheral lip forming a bead and the recess forms a rounded hollow groove with which it cooperates by friction before bonding, providing similar results; the upper part formed by the expanded IMVEA includes on its internal part a recess or a plurality of recesses or a plurality of blind holes, for example 5, 8, 10 or advantageously 15 or more than 15 and / or 20 holes, for example from 0.5 to 2 cm in diameter, for example between 0.8 cm and 1.2 cm.

[0032] They are arranged in the thickness of the inner part, for example by being distributed regularly or substantially regularly, and are of a variable depth and height depending on the progressive thickness of said upper part of the envelope, being less than said thickness, for example less than 2 mm to 1 cm, for example 5 mm, allowing internal expansion of the IMVEA at the time of demolding; the recesses or blind holes are filled (at least in part and / or for their remaining part after expansion and if necessary) by a compressible filling material, for example wicks inserted by force, for example expanded EVA of the same type as that of the upper part or the wedge; the upper part includes a heel part provided externally all around the heel and / or on either side of said heel, with a plurality of corrugations (for example two, three or four) forming pre-shockproof folds in case of heel compaction.This also makes it easier to accept / normalize the presence of the junction line at the point of gluing between the upper part and the sole part, which thus tends to blend visually into the mass; the lower face of the sole part is equipped with anti-slip means (for example formed by a plurality of grooves or studs) or is made of an anti-slip material (such as specially treated EVA or rubber…).

[0033] The present invention also relates to a method for manufacturing a prosthetic foot as described above.

[0034] It also relates to a method for manufacturing a four-part prosthetic foot, namely a spring-blade prosthesis with dynamic return, providing a compression space between a part of said blade, on the underside of the foot, and a part of said blade, on the top of the foot, extended by an end part directed upwards for connection with the user's leg, a two-part casing of said prosthesis, and an elastic plugging wedge arranged to completely fill said compression space, in which a first part of the casing or sole part is manufactured from a resin or an elastomer which is compressed in a first mold into a flat block giving it the shape of a specific sole,A second outer part or upper part is manufactured in parallel by injecting a liquid ethylene vinyl acetate resin expanded under pressure (expanded IMVEA) into a second mold comprising an upper part containing the negative shape of the top of the upper part, and a lower part having one or more protrusions or a plurality of studs, for example cylindrical, distributed (for example regularly) on its surface, a vertical passage block of complementary shape to the shape of the vertical end part of the blade of determined shape connecting with the leg of said user and containing the positive shape of the underside of the upper part to create the final shape of said upper part in expanded IMVEA, the protrusion(s) or stud(s) being arranged to create a plurality of recesses or blind holes in the upper part allowing internal expansion of the IMVEA at the time of demolding,In parallel, the elastic plugging wedge is manufactured, arranged to cooperate with and / or completely (or substantially completely, i.e., for example, at least 80% to 90% of the space) said compression space in a third mold by injection of expanded EVA. The plugging wedge is inserted and glued into the compression zone of the blade. The upper part of the foot blade and / or the inner face of the upper part of the shell are glued, and the entire blade and plugging wedge assembly is inserted into the upper part of the shell to which it is glued (by compression application). The inner face of the sole part and / or the lower face of the foot blade part are glued.and the peripheral parts of the lower surface of the upper part and of the upper surface of the sole part being glued (during a previous gluing and / or on this occasion) the sole part and its peripheral part are applied to the lower face of the blade and to the peripheral part of the lower face of said upper part of the shell for a determined time to glue them together and form a one-piece prosthetic foot.

[0035] Such a one-piece base is perfectly watertight and cannot be disassembled except by completely breaking it.

[0036] Advantageously, the recesses or blind holes in the upper part are filled before inserting the blade into said upper part.

[0037] Also advantageously the first sole forming mold is arranged to form on its peripheral part a first projecting edge or a first recess, and the upper part of the second mold includes a peripheral groove or a peripheral spar suitable for forming a second peripheral recess or a second peripheral projecting edge of shape substantially complementary to the first projecting edge or the first recess of the first sole forming mold.

[0038] Advantageously, the sole part is made of EVA obtained by mixing an ethylene vinyl acetate resin with a foaming agent in a determined proportion.

[0039] Advantageously the number of protrusions or spikes is greater than 10, for example between 10 and 30, for example 25 spikes, of variable height, for example decreasing in relation to the heel (i.e. to their distance from the outer end of the heel of the envelope), to take into account the variable thickness of the upper part of the envelope.

[0040] Also advantageously the vertical end part of determined shape connecting with the leg of said user is substantially parallelepiped.

[0041] The invention will be better understood upon reading the following description of embodiments given below by way of non-limiting examples. The description refers to the accompanying drawings in which:

[0042] Figure 1 is a lateral perspective view of a first embodiment of a prosthetic foot according to the invention.

[0043] This is a lateral perspective view of an example of a prosthetic blade usable in a prosthetic foot according to the invention.

[0044] This is a top view of the blade, the upward-facing end part of the connection is flattened after the mixed stroke.

[0045] This is a top view of the sole part of the prosthetic foot.

[0046] This is a view from below of the upper part of the prosthetic foot casing.

[0047] This is a view from below the base of the...

[0048] This is a top view of the foot envelope of the.

[0049] Laest is a set of three perspective views of a plugging wedge usable with the blade of the.

[0050] This is a lateral view of the prosthetic blade and the corresponding plugging wedge during its insertion.

[0051] This is the side view of the blade and the wedge after insertion.

[0052] This is a view from below of the upper part of the envelope of the prosthesis and in perspective of the prosthesis blade with wedge before insertion of one into the other.

[0053] This is a side view showing the step of inserting the blade with its plugging wedge into the upper part of the envelope, after gluing.

[0054] This is a side view showing the next step of placing the sole on the assembly obtained after the step of the, formed by the blade and the upper part after gluing.

[0055] Laest is a lateral view of the one-piece prosthetic foot obtained, comprising the prosthesis inserted and sealed tightly inside the shell according to the embodiment of the invention more particularly described with reference to the preceding figures, showing an excellent watertight and debris-proof junction between blade and shell, according to the invention.

[0056] This is a perspective view of another embodiment of a prosthetic foot according to the invention with a tip or connection for fixing to the user's leg.

[0057] There is a schematic lateral cross-sectional view of a prosthetic foot similar to that of the.

[0058] This is a flowchart of an embodiment of the manufacturing process of a prosthetic foot according to the invention.

[0059] This is a diagram of the operation of a device for manufacturing a prosthetic foot implementing the manufacturing process according to an embodiment of the invention.

[0060] This is a side view of the expanded EVA injection portion of the device.

[0061] This is a detailed schematic view of part of the device.

[0062] This is a top perspective view of a lower mold component for the upper part of a casing according to an embodiment of the invention.

[0063] This is a perspective view from below of an upper mold element for the upper part of the envelope corresponding to the lower mold element of the.

[0064] Lamontre a prosthetic foot P comprising a prosthetic foot shell 1 21, an example of which is blade-shaped and is described with reference to figures 2 and 3 below

[0065] The cover 1 comprises a sole part 2 made of elastomer or flexible plastic material and an upper part 3 obtained by injection molding of expanded EVA (IMVEA).

[0066] The prosthesis 21 (cf) with dynamic return usable with an envelope according to the invention is for example formed of a spring blade 22 having a body 23 substantially in the shape of an L, having a median section 24 of the bottom of the foot connected on one side 25 to a section 26 of the heel and on the other side 27 to a section 28 of the top of the foot comprising a spring part 29 extending above and progressively away from the median section 24.

[0067] The spring-loaded part 29 is extended by an upward-directed end part 33, for example vertical or substantially vertical, for connection to a fitting (not shown) worn by the user's leg.

[0068] The section 28 of the instep (cf) is for example in the form of an elongated blade 30 hollowed out by a central slit 31 terminated on the side opposite the heel by two fingers 32 thicker and wider than the rest of the blade, further improving the cushioning capacity at the end of the prosthesis and folded vertically around the line L (in dashed lines on the figure) to form the end part 33.

[0069] On the end part 33 is shown flattened after the line L in dashed line, in the extension of part 29. But in practice it is substantially perpendicular to said section and offset towards the front of the blade relative to the heel, as shown on the.

[0070] The prosthesis thus preserves the internal compression space or volume Vc between the median section 24 of the bottom of the foot and the part 29 of the section 28 of the top of the foot connected to the end part 33 of connection.

[0071] More specifically with reference to figures 4 to 7, the envelope 1 comprises a sole part 2 made of elastomer or soft plastic material and an upper part 3 obtained by injection molding of expanded EVA (IMVEA) delimiting an internal volume 4 and suitable for receiving and covering entirely the section 28 of the top of the foot of the body of the prosthesis, said upper part 3 being provided with a slot 5 (cf) for the exit of the end part 33 forming the junction of the prosthesis with the leg of the user (not shown).

[0072] This slot 5, for example parallelepiped, is arranged to allow the prosthesis to cooperate by friction (or contact) in a close and airtight and watertight manner with the upper part 3 of the envelope.

[0073] More specifically, with reference to figures 4 and 5, the peripheral part 6 of the upper face 7 of the sole part 2 is arranged to cooperate, for example by interlocking, and to be fixed by gluing, on the peripheral part 8 of the lower face 9 of the upper part 3. It is advantageously obtained by compression molding of EVA (CMVEA), for example after a first injection molding to give a first rough sole, before passing into a compression mold giving its final shape to the sole part.

[0074] The peripheral part 6 includes an edge 10 projecting from said upper face 7 of the sole part 2 and the peripheral part 8 of the upper part 3 includes a corresponding recess 11 arranged to cooperate with a gap (1 to 2 mm) and to fit together with the opposite edge 10 before the faces 7 and 8 are glued with a polymer glue of a type known per se.

[0075] The edges and recesses 10 and 11 (shown schematically in the figures) have, for example, a beveled or beaded shape while allowing easy adjustment during assembly, the junction 12 (see) becoming almost invisible once the parts are glued together.

[0076] In the particular embodiment of the invention described herein, the upper portion 3 formed by the expanded IMVEA comprises, on its inner part 13, a plurality of blind holes 14 (25 are shown here), cylindrical in shape, for example, 0.7 cm in diameter and with a height calculated based on the thickness relative to the inner portion. These holes are arranged to allow internal expansion of the IMVEA during demolding so that the external shape 15 (see) is homogeneous, regular, and conforms to the desired external design of the foot. The size of the holes is determined based on the overall expansion volume envisaged for the upper portion 3, either by calculation and / or empirical estimation within the grasp of a person skilled in the art.

[0077] The sole part is obtained by compression. It may or may not have blind holes 14' (cf), depending on whether the sole part is obtained after a first EVA extension step (presence of holes to compensate) before compression (CMVEA) or directly by compression.

[0078] In one embodiment, it is planned to fill the holes with EVA plugs (not shown) before forming the final prosthetic foot as will be described with reference to figures 11 to 14.

[0079] Figures 6 and 7 show the underside () and the top () of the envelope. The upper part 3 includes a heel part 16 externally provided with several undulations 17 on the side and on the back (see), for example three substantially horizontal and parallel undulations forming cushioning prefolds and also allowing to better conceal the existence of the necessary junction line 12 between upper part and sole part.

[0080] The lower or external face 18 of the sole part 2 is provided with anti-slip means 19, for example formed by concentric undulations 20 on the heel section on one side and on the toe section on the other.

[0081] Lamontre provides an example of a 34mm elastic spacer for sealing the compression space Vc defined by the blade when it is relaxed, as shown in the figure. An elastic spacer is defined as a spacer that can deform plastically to adapt to and allow the spring effect of the blade, without causing air displacement and / or requiring air evacuation and / or entry. For example, it is a spacer of a specific shape corresponding to the empty portion of the prosthesis made of expanded IMVEA with a hardness equal to or less than that of the upper portion.

[0082] Shore hardness is measured with a durometer in a way known in itself, for example by reference to the so-called Shore A scale. The hardness of the upper part is for example between 40 and 80 on this scale, and that of the wedge between 20 and 70.

[0083] More specifically, this wedge 34, or EVA or other shock-absorbing filler plug, is dimensioned and arranged to be placed between the free upper face of the middle section 24 of the blade's underside and the lower face 36 of the upper section 28 of the foot, extending above and at a distance from said middle section of the underside. These surfaces are shown as dashed lines in the figure. The rear part 37 of the wedge has a curved surface arranged to cooperate with the inner face 38 (see) of the heel of the upper part 3, a central edge 39 being provided to fit into the slot 31 opposite the blade.

[0084] We will now describe, with reference to figures 9 to 14, the manufacture of the prosthetic foot according to the method of implementation more particularly described here, starting from the prosthesis or blade described with reference to figures 2 and 3.

[0085] The first step consists of fitting (after gluing the opposite surfaces that are to come into contact) the wedge 34 into the recess or compression volume Vc of the prosthesis 21 in figures 2 and 3. (see figures 9 and 10).

[0086] Then the inner face 40 of the inner part 41 of the upper part 3 of the envelope 1, as well as the top 42 of the top surface of the blade, are glued on all their contact surfaces, before the end part 33 of the blade connection is embedded in the slot 5 until the middle part 24 of the blade is inserted into the recess or inner volume 4 provided in the bottom of the upper part 3 in expanded IMVEA.

[0087] This recess or internal volume 4 is dimensioned for a total insertion of the blade as shown on the diagram, so as to allow the total embedding of said blade in the upper part of the envelope by allowing contact between the internal face 40 of the upper part of the envelope and the top 42 over the entire surface of the top of said blade.

[0088] The next step consists of gluing the upper face 43 of the sole part 2 and / or the lower face 44 of the blade 2, on all or on the essential part (for example 90%) of their surfaces and in particular on their opposite peripheral edges, to obtain after compression of one on the other for a determined time, for example one or more minutes, for example 5 minutes, a prosthetic foot with envelope according to the invention.

[0089] We have represented on the other embodiment of a prosthetic foot 45 according to the invention, a similar type of which is more precisely described below with reference to the longitudinal section of the.

[0090] Lamontre in longitudinal section a prosthetic foot comprising an upper part 46 in expanded IMVEA, equipped with blind holes 47 filled with soft EVA 48 and a sole part 49 in CMVEA.

[0091] The upper surface 53 of the blade 52 is bonded to the inner face 50 of the internal cavity formed by the recess or internal volume 4 of the opposing upper portion 46, and the lower or underside face 51 of the blade 52 is itself bonded to the upper face of the sole portion. The blade 52 includes an end portion 55 for joining with a connector 56 for attaching to the user's leg stump (of a type known per se).

[0092] The end portion 55 of the blade 52 passes through and is bonded to the passage slot 57 of the upper portion 46 of the casing according to the invention. At this stage, the seal is complete, as the damping due to the dynamic deformation of the blade is absorbed by the elasticity of the casing and that of the wedge 34.

[0093] In the rest of the description, the same reference numbers will be used where appropriate to designate identical or similar elements.

[0094] This is an organizational chart of a process for manufacturing the prosthetic foot according to the embodiment of the invention more particularly described here.

[0095] First, the choice of a prosthesis is made by the user and his doctor, that is to say, the blade is determined in terms of shape and resistance according to the specifications, this being designed separately or chosen from a catalog of suppliers of dynamic return blades.

[0096] The user also determines (step 61) the choice of the specific cover he is looking for (appearance, colors, shape etc.), then we determine more precisely (step 62) in detail the cover (upper part, sole part and cushioning wedge) corresponding to the chosen prosthetic foot.

[0097] Next (general step 63) the first part of the cover or sole part 2 is manufactured by compressing EVA in a mold.

[0098] To do this, a first rough draft (step 64) is formed in an initial mold into which EVA is injected in liquid form comprising a foaming agent known in itself, and / or rubber or a mixture of the two, roughly blocking the shape of the retained sole, then said shape is placed in a first mold (step 65) of (high) compression (for example between 100 and 200 bars) allowing to obtain the sole part (step 66) in CMEVA of a determined shape and volume, then it is cooled substantially in ambient air in a wooden shell (step 67) in a one-to-one ratio, that is to say with a final volume of the sole after cooling equal to the internal volume of the mold.

[0099] Simultaneously, a second part of the envelope or upper part 3 is manufactured (overall step 68) by injection (step 69) of EVA under pressure (for example between 40 and 100 bars) into a second mold (comprising a lower part and an upper part), with the addition of a porogenic agent - (foaming gas in Anglo-Saxon terminology) - for example nitrogen and the addition of particles or nucleating agents in a way known and adapted by a person skilled in the art according to the characteristics of the EVA) then it is demolded (step 70) causing the sudden expansion of the expanded EVA (here the ratio is for example one to two), this expansion being nevertheless controlled thanks to the blind holes generated by the pins of the lower part in the upper part of the envelope.

[0100] Step 71 involves filling blind holes, for example with soft EVA plugs—soft EVA being understood as EVA capable of deforming / compressing in a completely reversible manner—to obtain, after cooling, for example within a wooden shell (step 72), the upper part ready for insertion. Simultaneously, step 73 involves manufacturing the shock-absorbing wedge in a third mold by injecting liquid EVA, resulting in a relatively soft and compressible part, similar to the plugs, which can be compressed elastically. The chosen prosthesis 21 is then presented (step 74) before step 75 involves gluing the various parts together.To do this, for example, polyurethane glue is used to glue the upper and lower surfaces of the prosthesis, including the connecting end, the wedge, and the upper and lower junction surfaces via their peripheral edges of complementary shapes of the upper and sole parts of the shell.

[0101] The wedge is then fitted into the prosthesis at 76 and the prosthesis into the upper part before the sole is assembled and permanently glued at 77 with said upper part, the respective peripheries of which are arranged to cooperate (with a set of adjustment).

[0102] We will now describe, with reference to figures 18 to 20, the device for manufacturing the prosthetic foot according to one embodiment of the invention.

[0103] The device 78 includes first elements detailed below. From an EVA (pellets) storage tank 80, it is heated to liquefy it in an oven 81. The EVA is then injected, for example at a pressure of 40 bars in 82 into the initial mold 83, called the shape-locking mold, with a slightly foaming agent, then the resulting paste 84 is compressed (pressure of 100 to 200 bars) in a first mold 85 known in itself, allowing the sole part 86 to be obtained in the desired shape.

[0104] Simultaneously and in a separate apparatus, EVA in the form of granules (reservoir 87) is supplied to a heated screw furnace 88 using for example the MUCELL process known to those skilled in the art, a process in which the liquefied EVA, for example at 180°C in the said screw furnace 88, is supplied with a foaming agent (gas) and nucleating agents (see also figures 18 and 19).

[0105] EVA is then injected, via an injection nozzle 89 for example with a sealing nozzle, into a second mold comprising an upper part 90 of negative shape 91 (in dashed lines on the) of the upper part (see also) and a lower part 92 having the pins for example cylindrical 93 (in dashed lines) (see also) of formation of the blind holes of the upper part 94 of the envelope and a vertical block 93' (in dashed lines) of passage of complementary shape to the shape of the end part directed upwards of blade of determined shape of connection with the leg of said user and containing the positive shape of the upper part, to create the final shape of said upper part in expanded IMVEA.

[0106] The second mold is then suddenly opened, causing an almost instantaneous expansion of the EVA (expanded IMEVA), a controlled expansion which will take place essentially towards the inside of the blind holes, thus surprisingly maintaining a controlled external shape.

[0107] The two parts sole 86 and upper 94 are then prepared (block 95) an insertion of plugs or plug being made in the remaining part of the blind holes not filled by the expansion.

[0108] Note that the cumulative volume of these blind holes must correspond substantially to the expected expansion volume, for example determined empirically and / or by calculation in a known way with the parameters concerning EVA, foaming and nucleating agents and the volumes concerned previously determined during the initial step 62.

[0109] The principle is that the expansion volume of the EVA is provided in the upper part of the mold via one or more solid volumes in the lower part, so that, during demolding, the expansion is inwards and not randomly outwards from the upper part of the resulting envelope.

[0110] The upper part 94 thus prepared and the sole part 86 are then brought to the gluing station 96, as well as the wedge 97 and the prosthesis or blade 98, station where the wedge 97, the blade 98, and the opposite faces of the upper and sole parts are glued.

[0111] Then at stations 99 and 100 the different elements are assembled one inside the other in an irremovable way by gluing before finishing heating at 101 to obtain the prosthetic foot 102 equipped with the cover according to the invention.

[0112] With reference to Figures 21 and 22, the lower member (92) of the second mold includes in its peripheral part a first projecting edge or a first peripheral recess (103) and the upper member (90) includes a second recess or a bearing surface (104) arranged to be placed opposite said first projecting edge or first recess when the lower and upper members are assembled, so that a first peripheral groove or a peripheral stringer is formed in the peripheral part of the lower face of the upper part of the envelope.

[0113] For its part, the first mold 85 is arranged to create a third peripheral obvious or peripheral protruding edge in the peripheral part of the upper face of the sole part of the envelope of substantially complementary shape so that they can cooperate with play with the peripheral spar or the first peripheral groove of the upper part when placed opposite each other.

[0114] As is self-evident and as follows from the foregoing, the present invention is not limited to the embodiments more particularly described but on the contrary embraces all variants and in particular those where the prostheses or blades are of different shapes, those where the internal expansion volume is in one part or in two or three outgrowths or volumes distributed regularly or not on the lower organ.

Claims

A prosthetic foot (P, 102) of a user comprising a prosthetic foot (21, 98) with a spring-loaded blade (22) known as a dynamic return blade, said blade providing a compression space (Vc) between a portion of said blade, known as the bottom blade, and a portion of said blade, known as the top blade, extended by an upward-directed end portion (33) for connection with the user's leg, and an outer casing (1) arranged to cover said prosthesis, characterized in that the casing (1) comprises a sole portion (2, 86) made of elastomer or flexible plastic material cooperating with the bottom blade portion and an upper portion (3, 94) obtained by injection molding of expanded EVA (expanded IMVEA) cooperating with the top blade portion and being provided with a slot (5) for the flush-friction exit of the upward-directed end portion (33), in which includes a wedge (34,97) of elastic sealing filling said compression space (Vc) and in that the sole part (2, 86) and the upper part (3, 94) are bonded together by their peripheral parts (6, 8). Prosthetic foot according to claim 1, characterized in that the upper face (7) of the sole part (2, 86) is glued to the underside blade part of the foot. Prosthetic foot according to any one of the preceding claims, characterized in that the inner face of the upper part of the shell is glued to the upper face of the section (23) of the top of the foot and the slot (5) for the passage with contiguous friction is glued to the end part (33) directed upwards for connection with the user's leg. Prosthetic foot according to any one of the preceding claims, characterized in that the sole part (2, 86) is obtained by compression molding of EVA (CMVEA). Prosthetic foot according to any one of the preceding claims, characterized in that the peripheral parts (6, 8) of the upper face (7) of the sole part (2) on the one hand and of the lower face (9) of the upper part (3) on the other hand, comprise for one a projecting edge (10) and for the other a corresponding recess (11) arranged to cooperate with play and fit together before gluing. Prosthetic foot according to any one of the preceding claims, characterized in that the upper part formed by the expanded IMVEA comprises on its inner part a recess or a plurality of recesses or blind holes (14, 47) arranged in the thickness of the inner part with a depth of height variable depending on the progressive thickness of said upper part of the envelope, allowing an internal expansion of the IMVEA at the time of demolding. Prosthetic foot according to any one of the preceding claims, characterized in that the recesses or blind holes (14, 47) are filled by a compressible filling material (48). Prosthetic foot according to any one of the preceding claims, characterized in that the upper part (3) comprises a heel part (16) provided externally around the heel and / or on either side of said heel with a plurality of undulations (17) forming shock-absorbing pre-folds in case of heel compression. Prosthetic foot according to any one of the preceding claims, characterized in that the lower face (18) of the sole part (2) is provided with anti-slip means (19, 20) or is formed of an anti-slip material. A method for manufacturing a prosthetic foot (P, 102) in four parts, namely a prosthesis (21, 93) in the form of a spring-loaded blade with dynamic return, providing a compression space (Vc) between a portion of said blade, on the underside of the foot, and a portion of said blade on the top of the foot extended by an end portion (33) directed upwards for connection with the user's leg, an outer casing (1) of said prosthesis in two parts (2, 86; 3, 94), and an elastic plugging wedge (34, 97) arranged to fill said compression space (Vc), wherein a first outer casing or sole portion (2, 86) is manufactured (63) from a resin or an elastomer which is compressed in a first mold (85) into a flat block giving it the shape of a determined sole (86), and a second (68) is manufactured in parallel envelope part or upper part (3,94) by injecting a liquid ethylene vinyl acetate resin expanded under pressure (expanded IMVEA) into a second mold (90, 92) comprising an upper part (90) containing the negative shape of the top of the upper part (3), and a lower part (92) having one or more protrusions or a plurality of studs (93) distributed over its surface, as well as a vertical passage block (93') of complementary shape to the shape of the end part (33) of a blade of determined shape connecting with the leg of said user and containing the positive shape of the underside of the upper part to create the final shape of said upper part (3) in expanded IMVEA, the protrusion(s) or stud(s) being arranged to create a plurality of recesses (14, 47) or blind holes in the upper part allowing internal expansion of the IMVEA at the time of demolding, the wedge (34, 73) is manufactured in parallel.97) elastic plug arranged to fill said compression space (Vc) in a third mold by injection of soft EVA, the plugging wedge (34, 97) is inserted and glued into the compression space (Vc) of the blade, the upper part of the top foot blade and / or the inner face of the upper part (3) of the casing is glued and the blade (21, 93) and plugging wedge (34, 97) assembly is inserted into said upper part of the casing to which it is glued, the inner face (7) of the sole part (2) and / or the lower face of the bottom foot blade part of the blade is glued, and the peripheral parts (6, 8) of the lower surface of the upper part (3) and of the upper surface of the sole part (2) are glued,The sole portion (2) and its peripheral portion (6) are applied to the lower face of the blade and to the lower peripheral portion (8) of the lower face (9) of the upper portion (3) of the casing for a specified time to bond them together and form a one-piece prosthetic foot. Method according to claim 10, characterized in that the recesses or blind holes (14, 47) of the upper part (3) are filled before inserting the blade into said upper part. A method according to any one of claims 10 and 11, characterized in that the first mold (85) for forming the sole (2, 86) is arranged to form on its peripheral part (7) a first projecting edge (10) or a first recess, and the upper member (90) of the second mold includes a peripheral groove (11) or a peripheral spar suitable for forming a second peripheral recess or a second peripheral projecting edge of shape substantially complementary to the first projecting edge or the first recess of the first mold (85) for forming the sole part (2).

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