CASTING MOLD FOR FINGER JOINT SPACERS

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the field of medical technology, in particular to devices for producing medical implants, and to the medical implants themselves that can be produced therewith. Furthermore, the invention relates to a manufacturing method in which the devices according to the invention are used for producing medical implants. TECHNICAL BACKGROUND

[0002] Spacers made of cured polymethylmethacrylate bone cement, used as temporary spacers in septic revisions, have long been known. The most common spacers are for knee, hip, shoulder, and elbow joints. In clinical practice, both industrially prefabricated spacers and those fabricated intraoperatively by the operating room staff are used. For larger joints, a wide variety of commercially available molds for intraoperative fabrication are known. These are generally intended for single use.

[0003] However, such spacer casting molds are not yet known in connection with finger joints. BRIEF DESCRIPTION OF THE INVENTION

[0004] Finger joints, including thumb joints, can be damaged, particularly by accidents and inflammatory diseases, necessitating replacement with artificial joints. Artificial finger joints can become infected by microorganisms, particularly bacteria. Infected artificial finger joints must then be surgically removed. Following debridement, a finger joint spacer, which may contain one or more antibiotics, can help calm the infection in the adjacent soft and bone tissue, in addition to systemic antibiotic treatment. Once the infection has been calmed and the finger joint spacers have been removed, artificial finger joints can then be implanted. Thus, a finger joint spacer can serve as a temporary placeholder for a medical implant to be inserted later in the treatment of a joint infection.

[0005] Joint injuries that result in loss of joint function can also lead to infections of the adjacent bone and soft tissue. In these cases, the infection must be calmed before artificial finger joints can be implanted. Following appropriate surgical debridement, spacers, preferably containing one or more antibiotic agents, can help calm the infection. It would be desirable to develop molds for finger joint spacers that would allow operating room personnel to easily produce finger joint spacers intraoperatively using polymethyl methacrylate bone cement paste. After the infection has been calmed and the finger joint spacers removed, joint function can then be restored by implanting artificial finger joints.

[0006] US20130183398A1 describes a mold for forming a temporary prosthesis, comprising at least two mold elements that are at least partially separable from one another. The at least two mold elements together define a substantially closed internal cavity for producing the temporary prosthesis. The mold comprises a fastening structure attached to the at least two mold elements for securing the at least two mold elements to one another during formation of the temporary prosthesis. The fastening structure is removable from the at least two mold elements by hand and without the use of a tool.

[0007] EP 2532323A1 relates to a mold for producing the tibial component of a knee joint spacer, which consists of at least three molded parts. A sleeve forms the edge region of the tibial component, a punch slidably arranged within the sleeve forms the femoral-side surface of the tibial component, and a cover forms the tibial-side surface of the tibial component. The mold has fixing devices on the sleeve and the punch to fix the punch in different positions within the sleeve.

[0008] US20180339440A1 discloses a cement mold assembly for forming a temporary implant for delivering antibiotics to an infected site. The cement mold assembly may include a first mold and a second mold. The first mold may have an open end and an inner wall. The first mold may define a cavity for forming the tibial component, including a cavity for forming the platform and a cavity for forming the stem. The second mold may have a body portion configured to be slidably and progressively received into the cavity forming the tibial component from the inner wall toward the closed end.By progressively advancing the second mold into the cavity forming the tibial component, cement in the cavity forming the tibial component is forced against the body portion and the inner wall to form a unitary tibial component having a tibial cup portion formed by the cavity forming the platform and a stem portion formed by the cavity forming the stem.

[0009] One object of the invention is therefore to develop a casting mold, for example made of plastic, that can be manufactured as cost-effectively as possible for the production of spacers using polymethyl methacrylate bone cement. It is desirable to be able to easily fill the casting mold with high-viscosity polymethyl methacrylate bone cement without pressure. The casting mold also enables the simple and reproducible production of finger joint spacers of various sizes. DETAILED DESCRIPTION

[0010] For the embodiments described herein, whose elements "have" or "comprise" a specific feature (e.g., a material), a further embodiment is always contemplated in which the element in question consists solely of the feature, i.e., does not comprise any further components. The word "comprise" or "comprising" is used herein synonymously with the word "have" or "having."

[0011] If an element is referred to in the singular in an embodiment, an embodiment in which several of these elements are present is also contemplated. The use of a term for an element in the plural generally also includes an embodiment in which only a single corresponding element is included. Unless otherwise stated or clearly excluded by the context, it is generally possible and hereby clearly contemplated that features of different embodiments may also be present in the other embodiments described herein. Likewise, it is generally contemplated that all features described herein in connection with a method are also applicable to the products and devices described herein, and vice versa. Merely for the sake of conciseness, all of these contemplated combinations are not explicitly listed in all cases.Technical solutions that are known to be equivalent to the features described herein are also intended to be encompassed by the scope of the invention.

[0012] A first aspect of the invention according to claim 1 relates to a device for producing finger joint spacers. The device comprises a lower part and an upper part. The lower part is connectable to the upper part. The lower part is permanently connected to the upper part at at least one point. The lower part comprises at least one first mold cavity. The upper part comprises at least one second mold cavity. The first mold cavity and the second mold cavity are each defined by an edge that delimits the mold cavity to the outside. Preferably, the first mold cavity and the second mold cavity can be connected to one another at their respective outer edges. The first mold cavity is configured to form a cavity together with the second mold cavity. This cavity is preferably formed by joining the first mold cavity to the second mold cavity as described above.This cavity serves to accommodate a bone cement dough from which a finger joint spacer can be formed. The shape of the spacer is defined by the shape of the cavity. The first mold cavity comprises a spacer body mold for forming a spacer body, and the second mold cavity comprises a shaft mold for forming a shaft. Preferably, the shaft mold and the spacer body mold are configured to form a continuous unit with one another when the lower part and the upper part are brought into contact with one another in a suitable manner. Accordingly, a spacer made of bone cement can preferably be formed from the device according to the invention, which spacer comprises a spacer body and a shaft, which together form a continuous unit. The spacer is a finger joint spacer. The spacer can be an articulating spacer or a non-articulating spacer.An articulating spacer is designed to form a joint together with another spacer.

[0013] In one embodiment, the first mold cavity, like the second mold cavity, can comprise a stem shape, so that the device can be suitable for producing a spacer with two stems. Such a spacer can, for example, be a non-articulating spacer. In one embodiment, a non-articulating spacer is designed to rigidly connect two different bones.

[0014] "Bone cement dough" refers herein to a moldable mass that can be hardened into a bone cement. Commercially available bone cements are often offered as a kit containing a liquid and a solid component. By mixing the liquid with the solid component, the user can create a bone cement dough that is easily moldable for a limited time. Shortly after mixing, the bone cement dough becomes tack-free, meaning it no longer adheres to a glove when lightly touched (as defined in ISO 5833:2002). In this state, a bone cement dough can preferably be poured into a mold cavity of the device according to the invention for producing spacers, for example, using a stirring spatula or a suitable dispensing device. Commercially available bone cements are often offered based on polymethyl methacrylate (PMMA).The device according to the invention can preferably be used with such a PMMA bone cement. However, it is also possible to use other types of bone cement.

[0015] The term "mold cavity" as used herein includes the "first mold cavity" and "second mold cavity" described herein.

[0016] The first mold cavity comprises a spacer body mold for forming a spacer body made of bone cement. The second mold cavity comprises a shaft mold for forming a shaft made of bone cement. The first mold cavity and the second mold cavity are configured to form a cavity together. The size of the cavity is dimensioned such that suitable spacer bodies made of bone cement can be produced with the device according to the invention, which can be implanted in the region of a human finger joint. The volume of the cavity corresponds to the sum of the volumes of the first mold cavity and the second mold cavity, which together form the cavity. For example, the cavity for receiving bone cement dough can have a volume of 0.1 to 5 cm³, preferably 0.3 to 4.0 cm³. Depending on the physiological conditions of a patient to be treated, larger or smaller volumes may be suitable.

[0017] A shaft is a part of a spacer that is preferably designed for insertion into bone tissue. The shaft shape can preferably comprise the shape of a solid of revolution. A solid of revolution is a geometric body whose surface is formed by rotating a generating curve around an axis of rotation. Examples of solids of revolution include a cone or a truncated cone. In one embodiment, the shaft shape has the shape of a truncated cone. The shaft shape can also comprise the shape of a pyramid or a truncated pyramid. A pyramid has a polygonal base (i.e., a polygon as the base) and several triangular side surfaces that touch at a common point. A truncated pyramid can be formed geometrically by cutting off a smaller, similar pyramid (supplementary pyramid) from a pyramid (initial pyramid) at the lateral surfaces parallel to the base.

[0018] The spacer body shape can preferably be substantially cuboidal or substantially hemispherical. A "substantially cuboidal" spacer body shape can also include a curved surface that deviates slightly from a geometrically precise cuboid basic shape, as described below.

[0019] The spacer body mold serves to form a spacer body, which can preferably comprise an articulating surface. An "articulating surface" is preferably configured to form a joint with a corresponding further articulating surface, similar to a human finger joint. For example, a rectangular-concave articulating surface can engage with a rectangular-convex articulating surface to form a hinge-like joint. Similarly, a hemispherical articulating surface can engage with a corresponding surface with a hemispherical recess, similar to a ball and socket joint. Such a suitable interaction between two spacers according to the invention preferably enables a patient implanted with such spacers to continue to move their fingers in a manner similar to that of a natural joint.Examples of the above-described interaction of two coordinated articulating surfaces in the manner of a hinge joint or ball joint are shown in the attached drawings.

[0020] Accordingly, the device according to the invention preferably comprises a spacer body mold with an end face which is configured to form an articulating surface which is suitable for forming a joint together with another articulating surface of a corresponding spacer body.

[0021] In some embodiments, it is therefore preferred that the end face of the spacer body mold has a curved shape, for example, a convex or concave shape. This allows, for example, spacers to be molded whose spacer bodies have an articulating surface with a concave shape, and can jointly form a joint with another spacer body with a corresponding articulating surface with a convex shape.

[0022] The device further comprises a flexible connecting element that connects the lower part to the upper part. The connecting element is preferably arranged at the edges of both the lower part and the upper part. The connecting element, in the form of a foil hinge, connects the lower part to the upper part.

[0023] In a further embodiment, the device comprises a first fastening element and a complementary second fastening element. By engaging the first fastening element with the second fastening element, the upper part can be connected to the lower part. For this purpose, the upper part can comprise a first fastening element, and the lower part can comprise a matching second fastening element, or vice versa. For example, the upper part can contain a pin which can snap into a socket or recess on the lower part in order to firmly clamp the upper part to the lower part. This allows the first mold cavity and the second mold cavity to be connected to one another in a matching position and to be held stably in this position in order to form the cavity for forming a spacer. Similarly, a clamp or clip, optionally with a suitable counterpart, can be provided as the fastening element.

[0024] In a preferred embodiment, the device according to the invention comprises both a connecting element and a first fastening element and a complementary second fastening element. This allows the lower and upper parts to be connected to each other particularly securely and fixed relative to each other in a desired orientation.

[0025] In a further embodiment, the device comprises a groove arranged circumferentially along at least one of the mold cavities. The groove is preferably arranged in spatial proximity to an edge of a mold cavity. The edge of a mold cavity refers to an edge at which the geometry of a mold cavity described herein, which is configured to form a cavity with a second mold cavity, is delimited to the outside.

[0026] The device may further comprise a web similarly arranged circumferentially along one of the mold cavities so that it can engage with a corresponding opposing groove of another mold cavity. This allows the lower part to be firmly connected to the upper part to seal the cavity formed jointly by the two mold cavities from the outside.

[0027] In a preferred embodiment, the groove can be deeper than the height of a matching bar, so that a void can be formed between the bar and the groove by the bar engaging the groove. This void can preferably be configured to accommodate excess bone cement. This can counteract the formation of burrs when taking impressions of spacers, since the excess bone cement absorbed by the void does not remain directly on the surface of the molded spacer.

[0028] In a further embodiment, the lower part and / or the upper part can comprise an opening for venting the cavity. Preferably, both the lower part and the upper part each comprise at least one such opening. It can be particularly advantageous to provide such openings both at the tip of the shaft mold and at several corners of the spacer body mold. Such an opening can ensure that the mold cavities and the cavity can be completely filled with bone cement dough. The air displaced by the bone cement dough can escape through an opening in the mold cavity.

[0029] The device according to the invention can in principle be made of any suitable material. Flexible, elastic materials can facilitate the removal of the molded spacers. The device can comprise a metal or a polymer. Examples of suitable polymers include rubber, silicone rubber, synthetic rubber, ethylene propylene diene rubber (EPDM), polyethylene, polyetheretherketone, and polypropylene. Devices made of polypropylene allow particularly easy removal of the hardened bone cement from the device. In some embodiments, the device is made of a transparent or at least translucent, i.e., optically translucent, material. Suitable transparent or translucent polymers are suitable for this purpose. This allows the user of the device to check whether the mold cavities are completely filled with bone cement dough.

[0030] A further aspect of the invention relates to a carrier on which several of the devices described above for producing a spacer are arranged on a flat surface. Each of the devices can be surrounded by recesses which allow the device to be removed from the carrier by severing the intermediate regions arranged between the recesses. The carrier can comprise different devices which differ, for example, in the shape and / or volume of the first and / or second mold cavities. For example, this can enable the user to select the most suitable device for different patients or joints to be treated. In the form of such a carrier, devices according to the invention can therefore be provided which can be used for a wide variety of different patients and purposes.The different devices on a carrier may also differ, for example, by the presence or design of the connecting elements, webs, grooves, and / or fastening elements described herein.

[0031] To further illustrate the invention, a finger joint spacer is also described, which, however, is not the subject of the present invention. Such a finger joint spacer can preferably be produced using a device described herein. The spacer can comprise a spacer body and a shaft. The shaft can be designed for anchoring in bone tissue. The spacer body can comprise an articulating surface. The articulating surface can be suitable for forming a joint together with another articulating surface of a corresponding spacer body, as already explained in detail herein in connection with the described device.

[0032] Furthermore, two spacers are described, the spacer bodies of which each have an articulating surface, which are designed to form a joint with each other.

[0033] In one embodiment, the spacer comprises or consists of bone cement. Preferably, the bone cement comprises PMMA. The bone cement may comprise an antibiotic. Examples of suitable antibiotics include gentamicin, clindamycin, and vancomycin. The spacer is preferably designed to temporarily replace a patient's natural joint, for example, a finger joint, in connection with a surgical procedure. "Finger joint" refers herein to all joints within the fingers, including the thumb. In one embodiment, the spacer can be used in the hand region, for example, in the region of the metacarpal bones.

[0034] The spacer, preferably a finger joint spacer, can be an articulating or non-articulating spacer, as described elsewhere herein in connection with the devices according to the invention. Optionally, the articulating spacers described herein can be connected to each other in pairs, for example, using bone cement, to form a non-articulating spacer.

[0035] A further aspect of the invention according to claim 14 relates to a method for producing a finger joint spacer, comprising the following steps, (i) Providing a device described herein for producing a spacer, (ii) Bringing the first mold cavity into contact with the second mold cavity to form a cavity sealed to the outside, (ii.a) Optionally connecting the lower part to the upper part by means of a first fastening element and a second fastening element complementary thereto, (ii.b.) Optionally, alternatively or in addition to step (ii.b.), connecting the lower part to the upper part by engaging a web in a groove, (iii) Introducing a bone cement dough into the first mold cavity and the second mold cavity, (iv) Curing the bone cement dough, (v) Opening the cavity by at least partially detaching the lower part from the upper part, and (vi) thereby obtaining a finger joint spacer made of bone cement, wherein step (iii) takes place before or after steps (ii), (ii.a) and (ii.b).

[0036] In a first step (i) of the method, a device according to the invention for producing a finger joint spacer is provided. For this purpose, a device as described above is used, which comprises a lower part and an upper part, wherein the lower part is connectable to the upper part, and wherein the lower part comprises a first mold cavity, and the upper part comprises a second mold cavity, wherein the first mold cavity is configured to form a cavity together with the second mold cavity, wherein the first mold cavity comprises a spacer body mold for forming a spacer body, and the second mold cavity comprises a shaft mold for forming a shaft.

[0037] In a second step (ii) of the method, the lower part of the device is brought into contact with the upper part of the device so that an outwardly sealed cavity is formed, as described in more detail herein in connection with the device above.

[0038] In an optional further step (ii.a) of the method, the upper part can be connected to the lower part using a first fastening element and a complementary second fastening element. For example, the upper part can comprise a pin that can engage in a matching recess on the lower part.

[0039] In an optional further step (ii.b) of the method, the lower part can be connected to the upper part by a web of the upper part engaging a groove in the lower part. Alternatively or additionally, a web of the lower part can engage a groove in the upper part.

[0040] In a third step (iii) of the method, bone cement dough is introduced into a first and a second mold cavity of the device. The mold cavities should preferably be filled completely with the bone cement dough and free of air bubbles. The bone cement dough can be added either before step (ii), i.e., bringing the first mold cavity into contact with the second mold cavity, or afterward. According to one embodiment, the bone cement dough can be added directly into the separate mold cavities, for example by spreading the bone cement dough using a spatula or using a suitable dispensing device. If the mold cavities are already joined together, the bone cement dough can be injected through an opening in one of the mold cavities into the cavity formed jointly by the first and second mold cavities.

[0041] In a fourth step (iv) of the process, the bone cement paste is cured. The bone cement paste typically contains reactive components that, after mixing, bond with each other through a chemical reaction within a few minutes, forming a hard, non-deformable material. This material is referred to as (cured) bone cement and forms the finger joint spacer according to the invention.

[0042] In a fifth step (v), the cavity containing the hardened bone cement is opened. To do this, the upper part is separated from the lower part. The upper part may still be connected to the lower part via a connecting element, but the cavities are no longer adjacent.

[0043] In a sixth step (vi), a finger joint spacer made of bone cement is obtained. This can now be removed from the device.

[0044] The steps of the method described above can, in principle, be performed in any order. In one embodiment, the method is carried out in the order described above. In another embodiment, the introduction of a bone cement dough occurs, for example, before the first mold cavity is brought into contact with the second mold cavity. EXAMPLES

[0045] The invention is defined by the claims and is further illustrated below by examples, which, however, are not to be construed as limiting. It will be apparent to those skilled in the art that other equivalent means may be used in a similar manner instead of the features described here. FIGURES

[0046] Figure 1 shows an example of a first embodiment of the invention. The device according to the invention comprises a lower part 101, which has at least one first mold cavity102 In Figure 1 In the example shown, the lower part 101 two first mold cavities 102. The first mold cavities 102 each include a spacer body shape 600 with a frontal face 501, 502. In the example shown here, one of the first two mold cavities comprises 102 an outwardly curved, i.e. convex, front surface 501, and the other of the first two mold cavities 102 comprises an inwardly curved, i.e. concave, front surface 502. The spacer bodies produced using these spacer body shapes are provided with matching articulating surfaces that can form a joint. The lower part also includes circular recesses as the first fastening element. 160.

[0047] The device further comprises an upper part 201 with at least one second mold cavity 202. In the example shown here, the top contains201 two second mold cavities 202. The second mold cavity 202 contains one shaft shape each 400, with which the shaft of a finger joint spacer can be manufactured. Part of the shaft mold 400 is therefore designed in this example in the shape of a truncated cone. The stems produced from it can therefore be designed to engage bone tissue. The upper part further comprises pin-shaped projections as a second fastening element. 161, which fits into the recesses of the lower part 160 can engage to align the mold cavities of the lower part with the mold cavities of the upper part and to hold them in this aligned position. In this case, a first mold cavity 102 and a second mold cavity 202 each pair has a cavity 300 This cavity 300is designed to be filled with bone cement dough to form a finger joint spacer from the bone cement dough. Furthermore, the lower part 101 using a connecting element 150 in the form of a foil hinge with the upper part 201 tied together. Figure 2 shows an enlarged view of the Figure 1 shown embodiment. The lower part 101 includes a groove 170, along the edge 110 a first mold cavity 102 The upper part 201 includes a bridge 171, along the edge 110 a second mold cavity 202 is arranged.

[0048] The edge 110 refers to the circumferential edge of a mold cavity up to which the respective mold cavity must be filled with bone cement dough at least so that the cavity 300After joining the lower part to the upper part, it is completely filled with bone cement dough.

[0049] Figure 3 shows schematically a section of an embodiment according to Figure 2 , whereby the lower part is connected to the upper part as described above, so that a first mold cavity forms a cavity with a second mold cavity in pairs. In this case, a web 171, which is arranged along a second mold cavity, into a groove 170 of a first mold cavity, whereby the web 171 the groove 170 seals off to the outside, and at the same time a closed empty space 172 between the bridge 171 and the groove 170 is formed. The empty space 172It can absorb excess bone cement dough that is forced out of the mold cavities when the lower and upper parts are joined. This can reduce or minimize the formation of burrs on the molded finger joint spacers.

[0050] Figure 4 shows an embodiment of the device according to the invention, in which the lower part 101 with the top 201 are brought into contact to form a cavity sealed to the outside. The lower part 101 is with the top 201 via a flexible connecting element 150 In the embodiment shown here, the shaft shape 400 a second mold cavity 202 an opening 180 which is located at the tip of the truncated cone-shaped shaft 400 This opening 180 can be used to remove air from the shaft shape 400 of the second mold cavity 202to escape when the second mold cavity 202 filled with bone cement dough. This allows for complete, air bubble-free filling of the device, especially the second mold cavity 202 and the cavity 300 (not shown in this figure) can be better ensured. If necessary, the opening 180 can also be used for filling bone cement dough.

[0051] Figure 5 A shows an embodiment of the device according to the invention, in which the upper part 201 under bending of the connecting element 150 towards the lower part 101 is moved to form the first mold cavity 102 with the second mold cavity 202 In this state, the first mold cavity 102 and the second mold cavity 202 already filled with bone cement dough.

[0052] Figure 5 Bshows the same device in a closed or "folded" state, in which the first mold cavity 102 with the second mold cavity 202 The two mold cavities together form a cavity that is sealed to the outside. Only via an optional opening 180 the cavity is accessible to the outside. Several such openings can also be provided. The first fastening element 160 engages the second fastening element 161 to firmly connect the two fastening elements together, and the first mold cavity 102 opposite the second mold cavity 202 in a fixed position so that a finger joint spacer in the

[0053] device can be manufactured.

[0054] Figure 6 shows a possibility of using the device according to the invention in a closed state according to Figure 5 Bto be filled with bone cement dough. For this purpose, an opening 180 Bone cement dough is used to create a mold cavity. In the example shown here, the opening is 180 at the tip of a shaft shape 400 This type of filling is particularly advantageous when using low-viscosity bone cement pastes.

[0055] Figure 7 A shows a device according to the invention, which has been reopened after the previously inserted bone cement dough has hardened. For this purpose, the first fastening element 160 from the second fastening element 161 dissolved, the groove 170 from the bridge 171 moved, and the top 201 from the lower part 101 released by a rotational movement, whereby the lower part 101 still has a connecting element 150 with the top 201 This opens the device and the molded finger joint spacer900 exposed.

[0056] Figure 7 B shows the removal of a finger joint spacer 900 of bone cement from the device according to the invention after it has been fully opened. In this open configuration shown here, the lower part 101 and the top 201 on a common level.

[0057] Figure 8 A shows a finger joint spacer 900, which has a shaft 500 and a spacer body 700 The spacer body 700 includes an articulating surface 800, which has a rounded, essentially rectangular geometry, and a curvature towards the inside of the spacer body 700 The articulating surface 800 is therefore concave.

[0058] Figure 8 B shows a finger joint spacer 900', which has a Figure 8 AThe finger joint spacer 900 has a complementary shape to the finger joint spacer 900 shown. This means that the finger joint spacer 900' comprises an articulating surface 800', which is configured to jointly form a joint from the two finger joint spacers by interacting with the articulating surface 800. For this purpose, the finger joint spacer 900' has a spacer body 700', which comprises a convex, i.e., outwardly curved, articulating surface 800'. Figure 8 C shows how the finger joint spacer 900 according to Figure 8 A and the finger joint spacer 900' according to the Figure 8 B together form a joint in that their two articulating surfaces 800 and 800' are brought into contact with each other.

[0059] Figure 9 shows a carrier 190 on which various devices according to the preceding figures are mounted on a flat surface 120 The individual devices are surrounded by several recesses 191which allow the devices to be separated by the intermediate areas 192, which are arranged between the recesses, are severed, for example with scissors or another cutting tool. Different devices according to the invention can be arranged on a carrier, for example devices with mold cavities. 102, 202, which have different geometries and / or sizes. For example, mold cavities with different volumes and / or mold cavities with essentially cuboid and hemispherical shapes can be mounted on a common support 190 be arranged.

[0060] Figure 10 shows a carrier 190 according to Figure 9 , in which one of the devices according to the invention is produced by separating the intermediate regions from the carrier 190 is removed.

[0061] Figure 11 shows a carrier 190 according to Figure 9from a different perspective. The geometry of the various mold cavities 102, 202 can be seen particularly well from this view. LIST OF SYMBOLS

[0062] 101Lower part 102First mold cavity 110Edge 120Flat surface 150Connecting element 160First fastening element 161Second fastening element 170Groove 171Web 172Void 180Opening 190Support 191Recess 192Intermediate area 201Upper part 202Second mold cavity 300Cavity 400Shaft shape 500Shaft 501, 502End face 600Spacer body shape 700, 701Spacer body 800, 800Articulating surface 900, 900Finger joint spacer

Claims

1. A device for producing finger joint spacers (900, 900'), comprising a lower part (101) and an upper part (201), it being possible for the lower part (101) to be connected to the upper part (201), the lower part (101) comprising a first mold cavity (102), and the upper part (201) comprising a second mold cavity (202), the first mold cavity (102) being configured to form a cavity (300) together with the second mold cavity (202), the first mold cavity (102) comprising a spacer body mold (600) for forming a spacer body (700), and the second mold cavity (202) comprising a shaft mold (400) for forming a shaft (500), characterized in that the device comprises a flexible connecting element (150) in the form of a film hinge, which connects the lower part (101) to the upper part (201).

2. The device according to claim 1, wherein the cavity (300) has a volume of 0.1 to 5 cm3, preferably 0.3 to 4.0 cm3.

3. The device according to claim 1 or 2, wherein the shaft mold (400) is in the shape of a solid of revolution, a pyramid or a truncated pyramid.

4. The device according to any of the preceding claims, wherein the spacer body mold (600) is substantially cuboidal or substantially hemispherical.

5. The device according to any of the preceding claims, wherein the spacer body mold (600) comprises an end face (501, 502) which is configured to form an articulating surface (800) which is suitable for jointly forming a joint with a further articulating surface (800') of a corresponding spacer body (700').

6. The device according to claim 5, wherein the end face (501, 502) has a curved shape, which is preferably convex or concave.

7. The device according to any of the preceding claims, wherein the connecting element is preferably arranged at the edge of the lower part (101) and the upper part (201).

8. The device according to any of the preceding claims, further comprising a first fastening element (160) and a second fastening element (161) complementary thereto, wherein the device is configured to connect the lower part (101) to the upper part (201) by engagement of the first fastening element (160) in the second fastening element (161).

9. The device according to any of the preceding claims, further comprising a groove (170) arranged peripherally along at least one of the mold cavities (102, 202).

10. The device according to claim 9, further comprising a projection (171) which is arranged and configured to engage form-fittingly in the groove (170) in order to outwardly seal the cavity (300) by connecting the lower part (101) to the upper part (201).

11. The device according to claim 10, wherein the groove (170) and the projection (171) are arranged and configured to form a void (172) between the projection and the groove by engagement of the projection (171) in the groove (170), which void is configured to receive excess bone cement.

12. The device according to any of the preceding claims, wherein the lower part (101) and / or the upper part (201) comprises an opening (180) which is configured to vent the cavity (300).

13. The device according to any of the preceding claims, wherein the lower part (101) and / or the upper part (201) comprise a polymer selected from the group consisting of rubber, silicone rubber, synthetic rubber, ethylene-propylene-diene rubber (EPDM), polyethylene, polyetheretherketone, and polypropylene, preferably polypropylene, wherein the polymer is further preferably transparent or translucent.

14. A method for producing a finger joint spacer, which comprises the following steps (i) providing a device according to any of claims 1 to 13, (ii) bringing the first mold cavity (102) into contact with the second mold cavity (202) of the device to form an outwardly sealed cavity (300), (ii.a) optionally connecting the lower part (101) to the upper part (201) by means of a first fastening element (160) and a second fastening element (161) complementary thereto, (ii.b.) optionally, alternatively or in addition to step (ii.b.), connecting the lower part (101) to the upper part (201) by engagement of a projection (171) in a groove (170), (iii) introducing a bone cement paste into the first mold cavity (102) and the second mold cavity (202), (iv) curing the bone cement paste, (v) opening the cavity (300) by at least partially detaching the lower part (101) from the upper part (201), and (vi) thereby obtaining a finger joint spacer made of bone cement, wherein step (iii) takes place before or after steps (ii), (ii.a) and (ii.b).