Waterproof prosthetic foot and manufacturing process for such a foot

Abstract

The invention relates to a user's waterproof prosthetic foot (P) and its manufacturing process. The foot comprises a prosthetic foot (21) and an outer casing (1) designed to cover said prosthesis. The prosthesis (21) has a spring-loaded blade (22) with dynamic return, and the casing comprises a lower part (2) and an upper part (3) obtained by injection molding of expanded EVA (expanded IMVEA). These parts of the casing and the spring-loaded blade are bonded together in a secure, non-removable, and completely waterproof manner. Figure for the abstract: Fig 1

Description

Title of the invention: Waterproof prosthetic foot and method for manufacturing such a foot

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

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

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

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

[0005] It therefore comprises a prosthesis body formed by a rigid part, called an "insert", for connection to a fixing part located on the user's leg, and a foot-shaped envelope, more or less realistic, but allowing the attachment of a shoe.

[0006] There are currently essentially two types of waterproof prosthetic foot.

[0007] The first type is called passive, or SACH (Solid Ankle Cushion Heel). Such a foot is, however, reserved for people with limited walking activity. For example, the Otto Bock 1WR95 prosthetic foot from the German company Otto Bock can be cited. This foot, with its rigid solid core and a connecting element attached to its upper wooden outer part to connect with the rest of the patient's prosthesis, 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 actually used very occasionally during a specific activity that may involve contact with water or sand, but the patient must then change to a prosthesis better suited to their daily activity level. Furthermore, 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] Of the same type, there is also a foot that is somewhat better suited to walking and activities requiring greater mobility. One example is the GERY foot from the French company PROTEOR. This foot consists of an EVA core into which an anchor-shaped connecting element is fitted at the top. It provides a connection with the rest of the patient's prosthesis. However, its considerable flexibility makes it unsuitable for patients with moderate to high activity levels. It is only indicated for patients with a relatively low activity level.

[0010] These foot prostheses have in common that they cannot integrate a prosthetic energy-returning blade into their manufacture and therefore offer in any case reduced functionality in terms of walking comfort or energy return, once again limiting this type of prosthesis to patients of low activity generally designated under category Kl.

[0011] The second type of waterproof or nearly waterproof prosthetic foot offers greater walking comfort. It incorporates a composite or plastic blade pre-inserted into a mold before liquid polyurethane is poured into it. An example is the IMPULSE foot from the American company Ohio WillowWood, which provides better functionality than simple SACH feet, but whose overall functional characteristics remain too far removed from high-performance prosthetic feet, such as energy-return feet, to be considered a replacement alternative for the majority of very active users.

[0012] While such feet are relatively watertight, they do have drawbacks related to their accelerated aging. Due to the nature of polyurethane, an open-cell material subject to degradation by hydrolysis upon prolonged contact with moisture and water, it is necessary to choose a relatively rigid version of polyurethane, which adversely affects the function of the prosthetic foot blades used. This reduces the functional capabilities of such feet and diminishes the possibility of providing active patients with a prosthetic foot that meets their needs in terms of walking comfort and energy return.

[0013] Moreover, these feet made of polyurethane are slippery on wet floors and present a significant risk of falls and injuries to their users, for example on wet tiles, a shower or bath floor.

[0014] In fact, as soon as one wishes to be able to use a prosthetic foot actively, it is necessary to use so-called active or dynamically returning feet. Such prosthetic feet are intended for amputees who engage in regular or intense walking, generally classified according to the patient mobility classification system as level 3 or 4, K3 or K4. It comprises a prosthesis consisting of a blade-shaped insert that is elastically deformable and made of composite material, carbon fiber, metal, or plastic, extending along the length of the foot and cooperating at its upper end with a leg attachment component. This blade, the length of which is adapted to the patient, moves in different directions. of flexion and presents a spring effect which plays an important role in walking by providing comfort and energy return.

[0015] But the major drawback of this foot is that it is not waterproof.

[0016] To ensure an aesthetic effect and allow for the attachment of a shoe, this type of prosthesis includes a removable, hollow foot shell, generally made of polyurethane, with an opening to allow it to be slipped around the lower part of the blade, like a shoe on a foot. To secure it around the blade, the shell clips onto the inside of the blade. The hollow shell thus only surrounds the lower part of the blade, allowing the blade to move and maintaining its spring-like effect, which is desirable for optimized gait for the patient.

[0017] This type of prosthetic foot is, by design and in fact, not waterproof. It requires constant maintenance and does not allow for versatile use of the prosthesis, particularly when swimming or walking on a beach, at the risk of damaging the blade, as impurities (sand, water, etc.) will inevitably penetrate between the blade and the shell through the opening in the shell.

[0018] The objective of the present invention is to provide 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 is truly waterproof, requires little or no maintenance, allows for 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 insensitive to moisture or water, and in that it can be made in many versions of energy-return prosthetic blades.

[0019] Another objective of the invention is to overcome the disadvantages of the prior art and to improve the comfort and walking capabilities of the user of a prosthetic foot that is waterproof and impurity-proof.

[0020] Another objective of the invention is to provide a prosthetic foot with good abrasion resistance and / or to be anti-slip.

[0021] 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.

[0022] The invention is based on the idea of ​​obtaining a prosthetic foot using a dynamic return prosthesis foot comprising a closed and non-removable casing or covering of the prosthesis foot, the latter being in the shape of a blade with determined characteristics, by bonding in a completely airtight manner a covering at least partially formed by EVA (Ethylene-Vinyl Acetate) or (IMEVA) (Anglo-Saxon initials for "Injected Moulded Ethylene Vinyl Acetate") injection molding in expanded form.

[0023] IMEVA in expanded form is obtained in a known manner by heating and The swelling of the EVA material allows for the creation of a closed cellular structure, giving 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).

[0024] EVA is a material used in the manufacture of adhesives, stretch films, and flexible gloves. While it offers good qualities in terms of flexibility and handling, 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 specifically addressed and found a way to overcome this drawback.

[0025] The blade is, for example, 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 (on the heel side) and connected on the other side (on the toe side) to a section of the top of the foot, for example substantially L-shaped or C-shaped, comprising a lower spring-like part extending above and progressively away from the median section and being extended (on the heel side) by an end part, directed upwards (in an inclined or curved manner), for example vertical or substantially vertical, for connection to a fitting worn by the user's leg.

[0026] To this end, the invention proposes in particular a waterproof prosthetic foot for a user comprising a prosthetic foot and an envelope arranged to cover said prosthesis, characterized in that the prosthesis has a spring blade called dynamic return, and in that the envelope comprises a lower part and an upper part obtained by injection molding of expanded EVA (expanded IMVEA), said parts of the envelope and the spring blade being fixed together by bonding in a solid, non-removable and completely waterproof manner.

[0027] By fully waterproof means a watertightness of the prosthetic foot corresponding to the IP standard (Anglo-Saxon initials for Ingress Protection) of the type IPX7 (resistant to temporary immersion up to one meter for 30 minutes), and advantageously IPX8 resistant to 2 m of immersion in depth for 2 hours.

[0028] The foot thus obtained forms a solid block or monobloc, all parts of which are fixed to each other by gluing and inseparable from each other without destruction of the foot.

[0029] The glue is, for example, a polyurethane type glue.

[0030] Advantageously the spring-blade foot prosthesis known as dynamic return provides a compression space between a part of the blade, called the bottom of the foot blade, and a part of the blade, called the top of the foot blade, extended by an upward-directed end part connecting with the user's leg, the upper part being provided with a passage slot for close friction exiting the upward-directed end part and in that the prosthetic foot includes an elastic plugging wedge inserted in the compression space.

[0031] The wedge is thus dimensioned and arranged to be placed between the upper face of an end section of the foot bottom blade and the lower face of the section of the foot top blade located vertically, that is to say extending above and at a distance from said end section of foot bottom.

[0032] By elastic filling shim, we mean a shim of reduced Shore hardness that can deform plastically to adapt to and allow the spring effect of the blade, without causing air displacement and / or requiring the evacuation and / or entry of such air. It is, for example, a shim of a specific shape corresponding to the empty portion or compression space of the prosthesis. It is, for example, made of expanded IMVEA with a hardness equal to or less than that of the upper portion.

[0033] Shore hardness is measured with a durometer in a manner 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.

[0034] In one embodiment, this plugging wedge, forming a shock-absorbing plug for filling the compression space, for example in expanded EVA, is pierced and / or crossed through by at least one recess that is watertight with respect to the prosthesis and opening onto the outside of the envelope, this recess being for example self-draining, that is to say that the water that could enter it would drain automatically and / or by compression when the foot is in the open air.

[0035] In an advantageous embodiment, this or these recesses open onto two or more lateral holes, for example opposite each other, opening onto the outside of the foot and made in one or more lateral faces of the upper part in a sealed manner with respect to the prosthesis.

[0036] In an advantageous embodiment, the lower part is a sole made of elastomer or flexible plastic material.

[0037] Advantageously the lower surface of the upper part and the upper surface of the sole part are in contact respectively with the opposite foot bottom and foot top blade, with which they are glued and the sole part and the upper part are glued together by their peripheral parts.

[0038] In other words, the inner face of the upper part of the cover is glued to the upper face of the upper foot blade part, the gap for the contact friction passage is glued to the upward-facing end part of the connection with the user's leg, and the upper face of the sole part is glued to the lower foot blade part.

[0039] In advantageous embodiments, one and / or other of the following provisions are also and / or otherwise made use of: - the sole is obtained by compression molding of EVA (CMVEA), previously expanded or not; The peripheral parts of the upper surface of the sole and the lower surface of the upper part each include a raised edge on one side and a corresponding recess on the other, designed to fit together with a slight play before bonding. For example, the raised edge is on the sole and the recess on the upper part. This allows for excellent adaptive interlocking, facilitating the absorption of variations during the injection / expansion of the expanded IMVEA. The raised edge and the recess may, for example, have a complementary beveled shape. This type of fit provides excellent bonding between the two parts while maintaining an aesthetically pleasing appearance, as the joint between them becomes barely noticeable or visible once bonded.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 ridge and the hollow forms a rounded hollow groove with which it cooperates by friction before gluing, 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.

[0040] They are arranged in the thickness of the internal part, for example by being distributed regularly or substantially regularly, and are of a depth of height varying according to 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 an internal expansion of the IMVEA at the time of demolding; - the recesses or blind holes are filled (for their remaining part after expansion and if necessary) by a compressible filling material, for example wicks inserted by force, for example in expanded EVA of the same type as that of the upper part or the wedge; - the upper part includes a heel section externally equipped all around the heel and / or on either side of said heel, with a plurality of undulations (for example two, three or four) forming pre-cushioning folds in case of heel compression; This also makes it easier to accept / normalize the presence of the junction line at the level of the gluing between the upper part and the sole part, which thus tends to blend visually into the mass; - the underside of the sole is equipped with anti-slip features (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....)

[0041] The present invention also relates to a method for manufacturing a prosthetic foot as described above.

[0042] It also relates to a method for manufacturing a four-part, watertight prosthetic foot, namely a spring-shaped prosthesis with dynamic return, a first outer shell or hollow sole part having an inner face, a second outer shell or hollow upper part having an inner face and obtained by injecting a liquid ethylene vinyl acetate resin expanded under pressure (expanded IMVEA), and an elastic sealing wedge arranged to fill the compression space of the spring blade in which - The plugging wedge is inserted and glued into the compression space of the blade. - The upper surface of the spring blade and / or the inner surface of the upper part are glued, and the blade and plugging wedge assembly is inserted into the hollow upper part of the casing to which it is glued. - glue is applied to the lower surface of the spring blade and / or the inner face of the sole part and the peripheral parts of the lower surface of the upper part and the upper surface of the sole part, - then 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 envelope for a determined time to form a one-piece prosthetic foot.

[0043] Such a foot, made of a single piece, is perfectly sealed and cannot be disassembled except by breaking it completely.

[0044] Advantageously the first part of the cover or sole part is formed from a resin or an elastomer which is compressed in a first mold into a flat block giving it the shape of a determined sole.

[0045] Also advantageously, the upper part of the envelope is formed by injecting a liquid expanded ethylene vinyl acetate resin under pressure (expanded IMVEA) into a second mold comprising an upper member containing the negative shape of the top of the upper part, and a lower member having one or more protrusions or a plurality of pins, 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 of connection with the leg of said user and containing the positive shape of the bottom of the upper part to create the final shape of said upper part in expanded IMVEA, the protrusion(s) or pins 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 its demolding.

[0046] Advantageously, the recesses or blind holes in the upper part are filled before inserting the blade into said upper part.

[0047] Also advantageously the first sole forming mold is arranged to form on its peripheral part a first protruding edge or a first recess, and the upper member of the second mold includes a peripheral groove or a peripheral spar suitable for forming a second peripheral recess or a second peripheral protruding edge of shape substantially complementary to the first protruding edge or the first recess of the first sole forming mold.

[0048] Advantageously the sole part is made of EVA obtained by mixing an ethylene vinyl acetate resin with a foaming agent in a determined proportion.

[0049] Advantageously the number of protrusions or studs is greater than 10, for example between 10 and 30, for example 25 studs, of variable height, for example decreasing with respect 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.

[0050] Also advantageously the vertical end part of determined shape of connection with the leg of said user is substantially parallelepiped.

[0051] 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:

[0052] The [Fig. 1] is a lateral perspective view of a first embodiment of a prosthetic foot according to the invention.

[0053] Fig. 2 is a lateral perspective view of an example of a prosthetic blade usable in a sealed prosthetic foot according to the invention.

[0054] Fig. 3 is a bottom view of the upper part of the envelope, a perspective view of a prosthetic blade and a top view of the sole part of the envelope according to the embodiment of the invention more particularly described herein.

[0055] Fig. 4 is a view from below of the prosthetic foot of Fig. 1.

[0056] Figure 5 is a schematic side view in section of another embodiment of a prosthetic foot according to the invention.

[0057] Fig. 6 is a flowchart of an embodiment of the process for manufacturing a prosthetic foot according to the invention.

[0058] Fig. 7 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.

[0059] Fig. 8 is a top perspective view of a lower mold member for the upper part of a casing according to an embodiment of the invention.

[0060] Fig. 9 is a perspective view from below of an upper mold member for the upper part of the envelope according to the embodiment of the invention referred to in Fig. 8.

[0061] Fig. 1 shows a prosthetic foot P comprising a foot prosthesis envelope 1 21, an example of which is blade-shaped and is described with reference to Figures 2 and 3 below.

[0062] The envelope 1 comprises a lower part or sole 2 made of elastomer or flexible plastic material and an upper part 3 obtained by injection molding of expanded EVA (IMVEA).

[0063] The prosthesis 21 (see [Fig.2]) 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.

[0064] 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.

[0065] The section 28 of the top of the foot 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.

[0066] The prosthesis preserves the internal compression space or volume Vc between the median section 24 of the bottom of the foot and the section 28 of the top of the foot connected to the end part 33 of the connection.

[0067] With reference to [Fig.3], the upper part 3 is obtained by injection molding of expanded EVA (IMVEA) delimiting the internal volume 40 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 an exit slot 5 from the junction of the prosthesis with the user's leg (not shown).

[0068] This slot 5, for example parallelepiped, is arranged to allow the prosthesis and its end part 33 to cooperate by friction in a close and airtight and watertight manner with the upper part 3 of the envelope.

[0069] 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 bonding, 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.

[0070] The peripheral part 6 includes an edge 10 projecting from said upper face 7 of the base 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 gluing the faces 7 and 8 with a polymer adhesive of a type known per se.

[0071] The edges and recesses 10 and 11 have, for example, a beveled or beaded shape while allowing easy adjustment during assembly, the junction 12 (see [Fig.1]) becoming almost invisible once the parts are glued together.

[0072] In the particular embodiment of the invention described herein, the upper portion 3 formed by the expanded IMVEA comprises, on its inner portion 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 [Fig. 1]) 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.

[0073] The sole portion is obtained by compression. It may or may not have blind holes 14', depending on whether the sole portion is obtained after a first EVA expansion stage (presence of holes to compensate) before compression (CMVEA) or directly by compression.

[0074] 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 6 and 7.

[0075] With reference again to [Fig.1], the upper part 3 includes a heel part 16 externally provided with several undulations 17 on the side and on the rear, 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.

[0076] The lower or external face 18 (see [Fig.4]) 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.

[0077] Figure 3 shows an example of an elastic filling wedge 34 for the internal volume, arranged to fill the compression space Vc delimited by the blade when it is relaxed, as shown in Figure 2. An elastic filling wedge is defined as a wedge that can deform plastically to adapt to and allow the spring effect of the blade, without causing air displacement and / or requiring the evacuation and / or entry of air that would remain trapped within the shell. For example, it is a wedge of a specific shape corresponding to the empty portion of the expanded IMVEA prosthesis, with a hardness equal to or less than that of the upper portion.This elasticity without air blockage in the shell can also be achieved for the wedge by means of a watertight recess relative to the prosthetic blade, pierced and / or passing through completely and opening onto the outside of the shell, this recess being for example self-draining, that is to say that any water that might enter it would drain automatically and / or by compression when the foot is in the open air.

[0078] Shore hardness is measured with a durometer in a manner 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.

[0079] More specifically, this wedge 34 or EVA or shock-absorbing filler plug is dimensioned and arranged to be placed between the free upper face of the median section 24 of the underside of the blade and the lower face 36 of the upper section 28 of the foot extending above and away from said median section of the underside. The rear portion 37 of the wedge has a curved surface arranged to cooperate with the inner face 38 of the heel of the upper part 3, a central edge 39 is provided to fit into the slot 35 opposite the blade.

[0080] Fig. 4 shows the lower or external face 18 of the sole part 2 in an embodiment in which it 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] Figure 5 shows another embodiment of a prosthetic foot 45 according to the invention in longitudinal section.

[0082] The prosthetic foot 45 comprises an upper part 46 made of expanded IMVEA, provided with blind holes 47 filled with soft EVA 48 and a sole part 49 made of CMVEA glued to the lower face 50 of the upper part opposite and to the lower face 51 of the spring blade 52, the upper face 53 of which is itself glued to the inner face 54 of the inner cavity of the upper part 46. The blade 52 comprises an end part 55 for joining with a connector 56 for fixing to the user's leg stump (of a type known per se).

[0083] The end portion 55 passes through and is bonded to the passage slot 57 of the upper portion 52 of the casing according to the invention. The seal at this stage is complete, the damping due to the deformation of the dynamic blade being absorbed by the elasticity of the casing and that of the wedge 34.

[0084] In the rest of the description, the same reference numbers will be used where appropriate to designate identical or similar elements.

[0085] Fig. 6 is a flowchart of an embodiment of the process for manufacturing the prosthetic foot according to the embodiment of the invention more particularly described herein.

[0086] First, the choice 60 of a prosthesis is made by the user and his doctor, that is to say, the blade of shape and resistance is determined in view of the specifications, this being designed separately or chosen from a catalog of suppliers of dynamic return blades.

[0087] The user also determines (step 61) the specific shell they are looking for (appearance, colors, shape, etc.). Then, the shell (upper part, sole part, and cushioning wedge) corresponding to the chosen prosthetic foot is determined more precisely (step 62) in detail.

[0088] Next (general step 63) the first part of the cover or sole part is manufactured by compressing EVA in a mold.

[0089] To do this, a first rough draft is formed (step 64) in a first mold into which EVA is injected in liquid form comprising a foaming agent known per se, and / or rubber or a mixture of the two, roughly blocking the shape of the retained sole, then said shape is placed in a second mold (step 65) of (strong) 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 is cooled substantially in ambient air in a wooden shell (step 67) (in a ratio one on one, that is to say with a final volume of the sole after cooling equal to the internal volume of the mold.

[0090] In parallel, a second part of the envelope or upper part is manufactured (global step 68) by injection (step 69) of EVA under pressure (for example between 40 and 100 bars) into a third mold, 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 those 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.

[0091] A step 71 of filling the blind holes, for example with soft EVA plugs—soft EVA being understood as EVA capable of deforming / compressing in a completely reversible manner—is then carried out to obtain, after cooling, for example in a wooden shell (step 72), the upper part ready for insertion. Simultaneously, a step 73 of manufacturing the damping wedge is carried out in a mold by injecting liquid EVA, resulting in a relatively soft and compressible part, similar to the plugs, subjected to elastic compression. The chosen prosthesis is then presented (step 74) before a step 75 of gluing the different parts together.To do this, for example, polyurethane glue is used to bond 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, which are complementary in shape to the upper and sole parts of the shell.

[0092] The wedge is then embedded in 76 of the prosthesis and of the prosthesis in the upper part before final assembly and gluing in 77 (by compression for a determined time depending on the capacities and characteristics of the glue used) of the sole with said upper part whose respective peripheries are arranged to cooperate (with a set of adjustment).

[0093] We will now describe, with reference to figures 7, 8 and 9, the device for manufacturing the prosthetic foot according to the embodiment more particularly described here.

[0094] From an EVA (pellets) storage tank 80, it is heated to liquefy it in a furnace 81. The EVA is then injected, for example at a pressure of 40 bar in 82 into a first mold 83, called a shape-locking mold, with a slightly foaming agent, and the resulting paste 84 is then compressed (pressure of 100 to 200 bar) in a second mold 85 known in itself allowing the sole part 86 to be obtained in the desired shape.

[0095] Simultaneously, 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, is supplied with foaming agent (gas) and nucleating agents in said screw furnace 88.

[0096] EVA is then injected, via an injection nozzle 89 for example with a sealing nozzle, into a third mold comprising an upper part 90 of negative shape 91 (in dashed lines on [Fig.7]) of the upper part (see also [Fig.9]) and a lower part 92 having cylindrical studs 93 (see also [Fig.8]) for forming blind holes in the upper part 94 of the envelope and a vertical passage block 93' of complementary shape to the shape of the upward-directed end part of the blade of determined shape for 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.

[0097] The third 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.

[0098] 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.

[0099] 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.

[0100] 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 envelope obtained.

[0101] 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 parts and sole are glued.

[0102] Then the different elements are assembled at stations 99 and 100 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.

[0103] With reference to figures 8 and 9, the lower member (92) of the second mold includes in its peripheral part a first protruding 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 protruding 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.

[0104] For its part, the first mold is arranged to create a third peripheral recess or a 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 they are placed opposite each other.

[0105] 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 encompasses 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

Demands

1. A user's waterproof prosthetic foot (P, 102) comprising a foot prosthesis (21, 98) and an envelope (1) arranged to cover said prosthesis, characterized in that the prosthesis (21, 98) has a spring blade (22) said to have dynamic return, and in that the envelope comprises a lower part (2) and an upper part (3) obtained by injection molding of expanded EVA (expanded IMVEA), said parts of the envelope and the spring blade being fixed together by bonding in a solid, non-removable and completely waterproof manner.

2. Prosthetic foot (P) according to claim 1, characterized in that it is watertight with a sealing corresponding to the IP (Ingress Protection) standard of value IPX7.

3. Prosthetic foot (P) according to claim 2, characterized in that it is IPX8 waterproof, resistant to 2 m depth in immersion for 2 hours.

4. Prosthetic foot (P) according to any one of the preceding claims, characterized in that the spring blade said to have dynamic return provides a compression space (Vc) between a part of the blade, said to be the bottom of the foot blade (24), and a part of the blade, said to be the top of the foot blade (28) extended by an end part (33) directed upwards for connection with the user's leg, the upper part being provided with a passage slot (5) with close friction exiting the end part directed upwards and in that the prosthetic foot includes an elastic plugging wedge (34) filling the compression space (Vc).

5. Prosthetic foot according to claim 4, characterized in that the plugging wedge (34) is made of expanded EVA and is traversed through and through by at least one recess opening onto the outside of the cover.

6. Prosthetic foot according to any one of the preceding claims characterized in that the lower part (2) is a sole made of elastomer or flexible plastic material.

7. Prosthetic foot according to claim 6, characterized in that the sole (2) is obtained by compression molding of EVA (CMVEA).

8. 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.

9. Prosthetic foot according to any one of the preceding claims, characterized in that the upper part (3) 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.

10. 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).

11. Method of manufacturing a four-part, watertight prosthetic foot (P, 102), namely a spring-shaped prosthesis (21, 93) with a dynamic return spring blade having a compression space (Vc), a first hollow shell or sole part (2) having an inner face, a second hollow shell or upper part (3) having an inner face and obtained by injection of a liquid ethylene vinyl acetate resin expanded under pressure (expanded IMVEA), and an elastic plugging wedge (34) arranged to completely fill the compression space (Vc) of the spring blade, in which: - the plugging wedge (34) is inserted and glued into the compression space (Vc) of the blade, - the upper surface of the spring blade and / or the inner surface of the upper part is glued, and the entire blade and plugging wedge assembly is inserted into the hollow upper part of the shell to which it is glued.- glue is applied to the lower surface of the spring blade (21) and / or the inner face of the sole part and the parts, peripherals (6, 8) of the lower surface of the upper part (3) and of the upper surface of the sole part (2), - then we apply the sole part (2) and its peripheral part (6) on the lower face of the blade and on the peripheral part (8) of the lower face (9) of said upper part of the envelope for a determined time to form said watertight prosthetic foot thus made monobloc.

12. Method according to claim 11, characterized in that the recesses or blind holes (14, 47) of the upper part are filled before inserting the blade into said upper part.

13. A method according to any one of claims 11 and 12, characterized in that the first part of the casing or sole part (2) is formed 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 (2), and the upper part (3) of the casing is formed by injecting a liquid ethylene vinyl acetate resin expanded under pressure (expanded IMVEA) into a second mold comprising an upper member (90) containing the negative shape of the top of the upper part, and a lower member (92) having one or more protrusions or a plurality of studs (93) distributed over its surface,a vertical (93') passage block of complementary shape to the shape of the vertical end portion of a blade of determined shape connecting with the leg of said user and containing the positive shape of the underside of the upper portion to create the final shape of said upper portion in expanded IMVEA, the protrusions or studs being arranged to create a plurality of recesses or blind holes in the upper portion allowing internal expansion of the IMVEA at the time of its demolding.