Prosthetic foot and manufacturing process of such a foot

Abstract

The invention relates to a prosthetic foot (P) for a user and a method for manufacturing such a foot. The foot comprises a spring-loaded prosthetic foot (21) with a dynamic return spring, having a compression space and an upward-facing end portion (33) for connection with the user's leg. It includes an outer casing designed to cover said prosthesis, comprising a sole portion (2) made of elastomer or flexible plastic material and an upper portion (3) obtained by injection molding of expanded EVA (expanded IMVEA) provided with a slit for a flush friction (or contact) passage of the upward-facing end portion (33), and an elastic plug filling said compression space, the sole portion (2) and the upper portion (3) being bonded together at their peripheral edges. Figure for the abstract: Fig 1

Description

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

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

[0002] It also relates to a method for manufacturing 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 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 several types of prosthetic foot.

[0007] The first type is called passive, or SACH (Solid Ankle Cushion Heel), and is 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 generally used only 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. 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, the GERY foot from the French company PROTEOR is also known. It is a foot consisting of an EVA (Ethylene-Vinyl Acetate) core into which an anchor-shaped element is fitted at the top, connecting it to the rest of the patient's prosthesis. Its high degree of flexibility makes it However, it is unusable for patients with medium or high activity levels, being indicated only for patients with low activity levels.

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

[0011] There is a second type, similar to the SACH foot but allowing the integration of a composite or plastic blade. The blade is inserted into a mold by casting, generally using liquid polyurethane, prior to the molding of the foot. Examples include the IMPULSE feet from the American company Ohio Woodwood, which offer better functionality than simple SACH feet, but whose functional characteristics still fall short of high-performance prosthetic feet such as energy-return feet and cannot be considered a sufficient replacement for the majority of very active users. 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 is unfavorable to the functioning of the blades.The functional capabilities of such feet are therefore limited and do not allow active patients to be offered a prosthetic foot that meets their needs in terms of walking comfort and energy return. Moreover, these feet, made of polyurethane, are very slippery on wet floors and generate a significant risk of falls and injuries, for example on wet tiles, shower or bath floors.

[0012] The third type of prosthetic foot known from the prior art is the so-called active or dynamic-return foot. It is 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. This insert extends the length of the foot and is connected at its upper end to a leg attachment. This blade, the length of which is adapted to the patient, moves in different directions of flexion and provides a spring effect that plays an important role in walking by providing comfort and energy return.

[0013] To ensure an aesthetic effect and allow for the attachment of a shoe, this type of prosthesis includes a hollow foot shell, generally made of polyurethane, which has an opening to allow it to be slipped around the lower part of the blade, like a shoe on a foot. The blade is fixed inside. The casing can be secured, for example, by a cleat integrated into its shape or by straps. To ensure it stays in place around the blade, one or more straps are used. The hollow casing therefore only surrounds the lower part of the blade, allowing for blade movement and maintaining its spring-like effect, which is desirable for optimized 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. It therefore does not allow for versatile use, particularly when swimming or walking on a beach, as this risks damaging the blade.

[0015] 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 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] IMEVA in expanded form is obtained in a known manner by heating and swelling the EVA material, creating a closed cellular structure that gives it damping and resilience properties. Advantageously, the part lower part or sole part is made of a more resistant material than expanded IMEVA for example in CMEVA (Anglo-Saxon initials for Compressed Moulded EVA).

[0021] EVA is a material generally used in the manufacture of adhesives, stretch films, or flexible gloves. While it offers good qualities in terms of flexibility and handling, it is, however, 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.

[0022] 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 of the sole 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.

[0023] 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 and upper parts are bonded together at their peripheral edges.

[0024] By elastic filling shim, we mean a shim of 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 the evacuation and / or entry of such air. For example, it is 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.

[0025] Shore hardness is measured with a durometer in a manner known per se, for example by reference to the so-called Shore A scale. The hardness of the upper part is by example between 40 and 80 on this scale, and that of the wedge between 20 and 70.

[0026] More specifically, this EVA or damping filler wedge or plug is dimensioned 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 vertically above, i.e. extending above and away from said bottom foot end section.

[0027] Advantageously the upper face of the sole part is glued to the underside blade part of the foot.

[0028] 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.

[0029] In advantageous embodiments, one and / or other of the following provisions are also and / or otherwise made use of: - the peripheral part of the upper face of the sole part is arranged to fit together and be fixed by gluing onto the peripheral part of the lower face of said upper part; - the sole part 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 have a protruding edge and a corresponding recess, arranged to cooperate with a slight play and adapt to each other before bonding. For example, the protruding edge may be on the sole and the recess on the upper part. However, the reverse can also be true. 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 may, for example, have a complementary beveled shape. Such a slight fit ensures excellent bonding of the two parts while providing an aesthetically pleasing external appearance, as the joint between the two becomes barely noticeable or visible once the parts are bonded 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 ridge, and the recess forms a rounded 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.

[0030] 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 (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 in expanded EVA of the same type as that of the upper part or the wedge; - The upper part includes a heel section equipped externally all around the heel and / or on either side of said heel, with a plurality of undulations (for example two, three or four) forming shock-absorbing pre-folds in case of heel compression. This also makes it easier to accept / normalize the presence of the junction line at the point of gluing between the upper and sole sections, which thus tends to blend visually into the mass; - the underside 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...).

[0031] The present invention also relates to a method for manufacturing a prosthetic foot as described above.

[0032] It also relates to a method for manufacturing a four-part prosthetic foot, namely a spring-blade-shaped prosthesis with dynamic return, providing a compression space 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 upward-facing end portion connecting with the user's leg, a two-part casing for said prosthesis, and an elastic sealing wedge arranged to completely fill said compression space, in which - A first part of the outer shell or sole is manufactured from a resin or 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. - glue is applied to the upper part of the blade on the top of the foot and / or to the inner face of the upper part of the envelope, and the blade and plugging wedge assembly is inserted into the upper part of the envelope to which it is glued (by compression application), - glue is applied to the inner face of the sole section and / or the underside of the foot blade section, 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 envelope for a determined time to glue them together and form a one-piece prosthetic foot.

[0033] Such a foot, made of a single piece, is perfectly sealed and cannot be disassembled except by breaking it entirely.

[0034] Advantageously, the recesses or blind holes in the upper part are filled before inserting the blade into said upper part.

[0035] 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.

[0036] Advantageously the sole part is made of EVA obtained by mixing an ethylene vinyl acetate resin with a foaming agent in a determined proportion.

[0037] 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.

[0038] Also advantageously the vertical end part of determined shape of connection with the leg of said user is substantially parallelepiped.

[0039] 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:

[0040] The [Fig. 1] is a lateral perspective view of a first embodiment of a prosthetic foot according to the invention.

[0041] Fig. 2 is a lateral perspective view of an example of a prosthetic blade usable in a prosthetic foot according to the invention.

[0042] Fig. 3 is a top view of the blade of Fig. 2, the upward-facing end part of the connection being flattened after the dashed line.

[0043] Fig. 4 is a top view of the sole part of the prosthetic foot of Fig. 1.

[0044] Fig. 5 is a bottom view of the upper part of the prosthetic foot shell of Fig. 1.

[0045] [Fig.6] is a view from below of the foot of [Fig.1].

[0046] Fig. 7 is a top view of the foot casing of Fig. 1.

[0047] Figure 8 is a set of three perspective views of a plugging wedge. usable with the blade of [Fig.2].

[0048] Fig. 9 is a lateral view of the prosthetic blade of Fig. 2 and the corresponding plugging wedge of Fig. 8 during its insertion.

[0049] Fig. 10 is the side view of the blade and wedge of Fig. 9 after insertion.

[0050] Fig. 11 is a bottom view of the upper part of the envelope of Fig. 5 and a perspective view of the prosthetic blade with wedge of Fig. 10 before insertion of one into the other.

[0051] The [Fig. 12] is a side view showing the step of inserting the blade with its plugging wedge into the upper part of the envelope of the [Fig. 11], after gluing.

[0052] Fig. 13 is a side view showing the next step of placing the sole on the assembly obtained after the step in Fig. 12, formed by the blade and the upper part after gluing.

[0053] Fig. 14 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 the blade and the shell, according to the invention.

[0054] Fig. 15 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.

[0055] There [Fig. 16] is a schematic cross-sectional lateral view of a prosthetic foot similar to that of [Fig. 15].

[0056] The [Fig. 17] is a flowchart of an embodiment of the process for manufacturing a prosthetic foot according to the invention.

[0057] The [Fig. 18] 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.

[0058] The [Fig. 19] is a side view of the expanded EVA injection portion in the device of the [Fig. 18].

[0059] Fig. 20 is a detailed schematic view of part of the device of Fig. 19.

[0060] Figure [Fig. 21] is a top perspective view of a lower mold component for upper part of the envelope according to an embodiment of the invention.

[0061] Fig. 22 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 Fig. 21.

[0062] Figure 1 shows a prosthetic foot P comprising a prosthetic foot shell 1 21, an example of which in the form of a blade is described with reference to Figures 2 and 3 below.

[0063] 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).

[0064] 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.

[0065] 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.

[0066] The section 28 of the top of the foot (see [Fig.3]) 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.

[0067] On [Fig.3] 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 [Fig.2].

[0068] 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.

[0069] 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 [Fig.5]) for the exit of the end part 33 forming the junction of the prosthesis with the leg of the user (not shown).

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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 [Fig.1]) becoming almost invisible once the parts are glued together.

[0074] 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. 7]) 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.

[0075] The sole part is obtained by compression. It may have blind holes 14' (see [Fig.4]) or not, 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.

[0076] 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.

[0077] Figures 6 and 7 show the underside ([Fig.6]) and the top ([Fig.7]) of the envelope of [Fig.1]. The upper part 3 includes a heel part 16 provided externally with several undulations 17 on the side and on the rear (see [Fig.1]), 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.

[0078] 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.

[0079] Figure 8 shows an example of a shim 34 for elastically sealing the compression space Vc delimited by the blade when it is relaxed, as shown in Figure 2. By elastically sealing shim, we mean a shim that can deform plastically shaped to adapt and allow the spring effect of the blade, without causing air displacement and / or requiring its evacuation and / or entry. For example, it is a wedge of a specific shape corresponding to the empty part of the prosthesis made of expanded IMVEA with a hardness equal to or less than that of the upper part.

[0080] 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.

[0081] More specifically, this wedge 34 or EVA or damping filler plug is dimensioned and arranged to be placed between the free upper face of the median section 24 of the blade's underside and the lower face 36 of the upper section 28 of the foot, extending above and away from said median section of the underside. These surfaces are shown as dashed lines in [Fig. 8]. The rear part 37 of the wedge has a curved surface arranged to cooperate with the inner face 38 (see [Fig. 5]) of the heel of the upper part 3, a central edge 39 being provided to fit into the slot 31 opposite the blade.

[0082] We will now describe, with reference to figures 9 to 14, the manufacture of the prosthetic foot according to the embodiment more particularly described here from the prosthesis or blade described with reference to figures 2 and 3.

[0083] The first step consists of embedding (after gluing the opposite surfaces suitable for contacting each other) the wedge 34 in the recess or compression volume Vc of the prosthesis 21 of figures 2 and 3. (see figures 9 and 10).

[0084] 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.

[0085] This recess or internal volume 4 is dimensioned for a total insertion of the blade as shown in [Fig. 13] and 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.

[0086] 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, over all or most (for example 90%) of their surfaces and in particular on their opposite peripheral edges, to obtain, after compressing one against the other for a determined time, by example one or more minutes, for example 5 minutes, a prosthetic foot with a casing according to the invention.

[0087] Figure 15 shows another embodiment of a prosthetic foot 45 according to the invention, a similar type of which is described in more detail below with reference to the longitudinal section of Figure 16.

[0088] Fig. 16 shows in longitudinal section a prosthetic foot comprising an upper part 46 in expanded IMVEA, provided with blind holes 47 filled with soft EVA 48 and a sole part 49 in CMVEA.

[0089] 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 bottom 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).

[0090] 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. 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.

[0091] In the rest of the description, the same reference numbers will be used where appropriate to designate identical or similar elements.

[0092] The [Fig. 17] is a flowchart of a process for manufacturing the prosthetic foot according to the embodiment of the invention more particularly described herein.

[0093] First, the choice 60 of a prosthesis is made by the user and his doctor, that is to say, the blade 21 is determined in shape and resistance according to the specifications, this being designed separately or chosen from a catalog of suppliers of dynamic return blades.

[0094] The user also determines (step 61) the choice of the specific cover he is looking for (appearance, colors, shape etc.), then the cover (upper part, sole part and cushioning wedge) corresponding to the chosen prosthetic foot is determined more precisely (step 62) in detail.

[0095] Next (general step 63) the first part of the cover or sole part 2 is manufactured by compressing EVA in a mold.

[0096] To do this, a first rough shape is formed (step 64) in an initial mold into which liquid EVA is injected, comprising a foaming agent of known per se, and / or rubber or a mixture of the two, roughly blocking the shape of the desired sole. This shape is then placed in a first (high) compression mold (step 65) (for example, between 100 and 200 bars) to obtain the sole part (step 66) in CMEVA of a given shape and a determined volumes, then we cool substantially in ambient air in a wooden shell (step 67) in a one-to-one ratio, that is, with a final volume of the base after cooling equal to the internal volume of the mold.

[0097] In parallel, a second envelope part 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 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.

[0098] 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 third mold by injecting liquid EVA, resulting in a relatively soft and compressible part, for example, of the same type as the plugs, subject to elastic compression. The chosen prosthesis 21 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 joining surfaces via their peripheral edges, which are complementary in shape to the upper and sole parts of the shell.

[0099] The wedge is then embedded in 76 in the prosthesis and the prosthesis in the upper part before final assembly and gluing in 77 of the sole with said upper part whose respective peripheries are arranged to cooperate (with a set of adjustment).

[0100] We will now describe, with reference to figures 18 to 20, the device for manufacturing the prosthetic foot according to an embodiment of the invention.

[0101] The device 78 comprises 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.

[0102] In parallel 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, is supplied with foaming agent (gas) and nucleating agents in said screw furnace 88 (see also figures 18 and 19).

[0103] 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 [Fig. 18]) of the upper part (see also [Fig. 22]) and a lower part 92 having the pins for example cylindrical 93 (in dashed lines) (see also [Fig. 21]) 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 upward-directed end part of the 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.

[0104] The second mold is then opened abruptly 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.

[0105] 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.

[0106] 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.

[0107] 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, when demolding, the expansion is inwards and not randomly outwards from the upper part of the envelope obtained.

[0108] 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.

[0109] 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.

[0110] With reference to figures 21 and 22, 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.

[0111] For its part, the first mold 85 is arranged to create a third one obviously peripheral or a peripheral projecting edge in the peripheral part of the upper face of the base 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.

[0112] 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

Demands

1. 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 having a slot (5) for the close-fitting passage of the end portion (33) directed upwards, in that it comprises 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).

2. Prosthetic foot according to claim 1, characterized in that the upper face (7) of the sole part (2, 86) is glued to the underfoot blade part.

3. 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 butt friction is glued to the end part (33) directed upwards for connection with the user's leg.

4. 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).

5. 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 recess (11) corresponding pieces arranged to cooperate with the game and adapt to each other before gluing.

6. 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.

7. 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).

8. 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.

9. 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.

10. Method of manufacturing a prosthetic foot (P, 102) in four parts, namely a prosthesis (21, 93) in the form of a spring blade said to have dynamic return, providing a compression space (Vc) between a part of said blade, bottom of foot, and a part of said blade top of foot extended by an end part (33) directed upwards for connection with the user's leg, of an envelope (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), in which a first part of the cover or sole part (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), a second part of the cover or upper part (3, 94) is manufactured (68) in parallel by injection of a liquid ethylene vinyl acetate resin expanded under pressure (IMVEA;

11.

12. expanded) in a second mold (90, 92) comprising an upper element (90) containing the negative shape of the top of the upper part (3), and a lower element (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 portion (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 studs 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 elastic plugging wedge (34, 97) arranged to fill said compression space (Vc) is manufactured (73) in parallel 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 blade's foot 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 blade's foot section is glued, and the peripheral parts (6, 8) of the lower surface of the upper part (3) and the upper surface of the sole part (2) are glued. The sole part (2) and its peripheral part (6) are applied to said lower face of the blade and to the lower peripheral part (8) of the lower face (9) of said upper part (3) of the casing for a predetermined time to glue them together and form a foot. one-piece prosthesis. 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 a first edge on its peripheral part (7). projecting (10) or a first obvious, and the upper part (90) of the second mold includes a peripheral groove (11) or a peripheral stringer suitable for forming a second peripheral obvious or a second peripheral projecting edge of shape substantially complementary to the first projecting edge or the first obvious of the first mold (85) for forming the sole part (2).

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