Foundry mold for rimless acetabular spacer

Abstract

The invention relates to a casting mold for preparing a acetabular spacer, comprising a main body with a curved first half mold and a curved second half mold, a first extension and a second extension, a filling nozzle and a first channel, wherein the first half mold together with the second half mold defines a cavity, wherein the first extension and the second extension are arranged next to each other on the main body and together define a cut-out area of the main body, wherein the cut-out area is arranged between the first extension and the second extension, and wherein the first channel is designed to allow excess bone cement to escape from the cavity of the casting mold.

Description

Technical Field

[0001] This invention relates to the field of medical technology, and more particularly to an apparatus for preparing medical implants and the medical implants themselves that can be prepared using the apparatus. Furthermore, this invention relates to a method of preparation in which a medical implant is prepared using the apparatus according to the invention. Background Technology

[0002] Spacers made of polymethyl methacrylate (PMMA) bone cement (potentially containing one or more antibiotics) have been successfully used in two-stage revision surgery for periprosthetic joint infections. After removal of the infected joint prosthesis and subsequent debridement, the spacer serves as a temporary implant during the transition period until the revision prosthesis is implanted. During this transition period, one or more antibiotics may be released from the spacer, which may help alleviate the infection. The spacer is used for "dead space management," i.e., treating surgically or infection-related cavities, and to prevent ligament and muscle atrophy.

[0003] In a two-stage revision surgery for periprosthetic hip infection, the prosthesis stem with the prosthesis head and the acetabulum are removed in the first surgery. During the transition phase, the hip spacer typically consists of a shaft made of polymethyl methacrylate (PMMA) with a spherical or mushroom-shaped head. The head has such a large diameter that it can be inserted directly into the acetabulum (hip socket) on the bone. However, the problem is that during joint movement, the spacer head may rub against the bone surface of the acetabulum.

[0004] Alternatively, so-called acetabular cup spacers have been developed, which replicate the hip socket. These spacers are cup-shaped spacers with a concave surface for receiving the spacer head and a convex back, and can be anchored in the acetabulum using polymethyl methacrylate bone cement dough.

[0005] EP3761909EPB1 discloses a hemispherical acetabular cup spacer. On the outer side, a groove or extension extends from the edge of the spacer and is oriented toward the center of the hemisphere.

[0006] US12127944B2 discloses a two-part casting mold consisting of a concave portion and a convex portion. The concave portion of the casting mold is connected to the convex portion by a threaded connection. The convex portion contains an opening for injecting polymethyl methacrylate bone cement. Additionally, tubular vent holes are arranged at the edges of the convex portion. Flash can be formed on the cast spacer at the point where the two portions separate. Flash can be very sharp and can only be mechanically removed with considerable effort, especially when the flash is about 0.3 mm or more thick. Such large flash can be broken off with pliers or trimmed with a milling cutter, which is cumbersome for medical users and makes it difficult to achieve the desired shape of the spacer. Detailed Implementation

[0007] One object of the present invention is to provide a casting mold, specifically for intraoperative preparation of acetabular cup spacers made of polymethyl methacrylate bone cement. The casting mold according to the invention aims to minimize the formation of flash on the spacer. Another object of the invention is to prevent air ingress into the prepared spacer. The invention also addresses the objective of minimizing the formation of gates, or at least minimizing and easily removing gates formed during molding.

[0008] Furthermore, an objective of this invention is to make the removal of the shaped spacer from the casting mold as easy, quick, and safe as possible for medical users. Specifically, the risk of cuts due to burrs from sharp edges should be avoided. Another risk of cuts may arise if a medical user slips while cutting the casting mold with a scalpel. Therefore, in some embodiments, the casting mold according to the invention allows for safe and harmless cutting of the casting mold. Another objective of this invention is to manufacture the casting mold as cost-effectively as possible. This includes, for example, the selection of the material used for the casting mold and the simplest possible geometric design of the casting mold.

[0009] The casting mold described herein, and more particularly the casting mold described in the claims, achieves a single purpose, multiple purposes, or all of these purposes.

[0010] Preferred implementation scheme

[0011] In a first embodiment, one aspect of the invention relates to a casting mold for preparing an acetabular spacer, the casting mold comprising: a body having a curved first half and a curved second half, a first extension and a second extension, a filling nozzle and a first channel, wherein the first half and the second half together define a cavity, wherein the first extension and the second extension are arranged adjacent to each other on the body and together define a cutting region of the body, wherein the cutting region is arranged between the first extension and the second extension, and wherein the first channel is designed to allow excess bone cement to escape from the cavity of the casting mold.

[0012] The second implementation involves a casting mold as described in the first implementation mentioned above, wherein the body has a first wall thickness that is thicker than the second wall thickness of the cutting area.

[0013] The third embodiment relates to a casting mold as described in the first or second embodiment mentioned above, wherein the first extension and the second extension are designed to guide a scalpel along the cutting area to cut through the casting mold.

[0014] The fourth embodiment relates to a casting mold according to any one of the preceding embodiments, wherein the first extension and / or the second extension includes tabs to facilitate manual opening of the first half and the second half.

[0015] The fifth embodiment relates to a casting mold according to any one of the foregoing embodiments, wherein the first extension and / or the second extension extends outward from the body by at least 2 mm, more preferably at least 3 mm, 4 mm, 5 mm or 6 mm.

[0016] The sixth embodiment relates to a casting mold according to any one of the preceding embodiments, wherein the first extension and / or the second extension extends circumferentially around at least half of the circumference of the body.

[0017] The seventh embodiment relates to a casting mold according to any one of the foregoing embodiments, the casting mold further comprising means for cutting off the gate, wherein the means preferably includes a movable element, which is also preferably selected from channels and protrusions.

[0018] The eighth embodiment relates to a casting mold according to any one of the foregoing embodiments, the casting mold further comprising a plug for closing the filling nozzle, wherein the first channel is preferably arranged in the plug.

[0019] The ninth embodiment relates to a casting mold according to the eighth embodiment, wherein the casting mold is designed and configured to cut off the gate by rotational movement of the plug relative to the filling nozzle.

[0020] The tenth embodiment relates to a casting mold according to the eighth or ninth embodiment, wherein the plug includes a first protrusion for cutting off the gate, the first protrusion being preferably disposed at the first channel.

[0021] The eleventh embodiment relates to the casting mold described in embodiment ten, wherein the first protrusion includes a beveled cutting edge.

[0022] The twelfth embodiment relates to a casting mold according to any one of the preceding embodiments, wherein the filling nozzle includes a second protrusion for cutting off the gate, wherein the casting mold preferably also includes a first protrusion according to the tenth embodiment, and wherein the casting mold is preferably designed and configured to cut off the gate by rotational movement of the plug relative to the filling nozzle when the first protrusion rotates relative to the second protrusion.

[0023] The thirteenth implementation plan relates to a casting mold according to any one of the aforementioned implementation plans eight to twelve, wherein the first channel is eccentrically arranged in the plug.

[0024] The fourteenth embodiment relates to a casting mold according to any one of embodiments eight to thirteen, wherein the filling nozzle further includes a second channel, wherein the casting mold is designed and configured to arrange the first channel along an axis common to the second channel in a first rotational position of the plug, and to arrange the first channel outside the axis common to the second channel in a second rotational position of the plug.

[0025] The fifteenth embodiment relates to a casting mold according to any one of the preceding embodiments, the casting mold further comprising an operating element accessible from the outside of the casting mold and designed and configured to cut off the gate.

[0026] The sixteenth embodiment relates to a casting mold according to any one of the foregoing embodiments, the casting mold further comprising a venting opening, wherein the venting opening is preferably disposed between the first half mold and the second half mold.

[0027] Another aspect relates to the use of the casting mold according to any one of the foregoing embodiments for the preparation of acetabular spacers.

[0028] Another aspect relates to a method for manufacturing an acetabular spacer, the method comprising the following steps:

[0029] Provide a casting mold according to any one of embodiments 1 to 16;

[0030] The casting mold was filled with bone cement.

[0031] The bone cement is hardened in the casting mold;

[0032] Remove any gates formed by the bone cement;

[0033] The main body of the casting mold is cut open in the cutting area (116);

[0034] Separate the first half of the mold from the second half of the mold (112); and

[0035] Remove the prepared acetabular spacer from the cut casting mold. Attached Figure Description

[0036] Figure 1 A cross-section of a first embodiment of the invention is shown by way of example.

[0037] Figure 2 A cross-section of one embodiment of the plug is shown by way of example.

[0038] Figure 3 A cross-section of another embodiment of the invention is shown by way of example.

[0039] Figure 4 Another embodiment of the invention is shown by way of example.

[0040] Figure 5 A casting mold filled with bone cement according to the present invention is shown by way of example.

[0041] Figure 6 A casting mold according to the invention is shown by way of example, which has been cut open.

[0042] Figure 7 Details of a casting mold in a first position are shown, the casting mold including a filling nozzle with operating elements.

[0043] Figure 8 A top view showing details of a casting mold in a first position is shown, the casting mold including a filling nozzle with operating elements.

[0044] Figure 9 Details of a casting mold in a second position are shown, the mold including a filling nozzle with operating elements.

[0045] Figure 10 A top view showing details of a casting mold in a second position is shown, the casting mold including a filling nozzle with operating elements.

[0046] Figure 11 A casting mold and a bone cement dispensing device according to the present invention are shown, the bone cement dispensing device being arranged for connection to the casting mold. Detailed Implementation

[0047] Regarding the embodiments described herein, where an element "has" or "comprises" a particular feature (e.g., a material), it is always anticipated in principle that another embodiment exists in which the relevant element consists solely of that feature, i.e., excluding any other components. The word "comprises" is used synonymously with the word "has" herein.

[0048] In one implementation, if an element is represented by a singular number, it is also expected that there are implementations containing more than one such element. The use of the terminology for plural elements also, in principle, includes implementations containing only a single corresponding element.

[0049] Unless otherwise indicated or clearly excluded based on context, it is in principle possible, and thus clearly expected, for features of different embodiments to also exist in other embodiments described herein. Similarly, it is in principle expected that all features described herein in combination with the method also apply to the casting molds and spacers described herein, and vice versa. Not all combinations of these considerations are explicitly listed in all cases, simply for the sake of brevity.

[0050] A first aspect of the invention relates to a casting mold for preparing a spacer. The casting mold according to the invention is particularly suitable for preparing acetabular spacers. Such spacers are also referred to herein as acetabular cup spacers. Such spacers replicate the shape of the acetabular fossa of the hip joint. The acetabular spacer typically includes a cup-shaped mold having a concave surface to receive a joint head or spacer head. Furthermore, the acetabular spacer typically includes a convex back that can be attached to the acetabulum using bone cement.

[0051] The casting mold according to the invention includes a body formed by a curved first half-mold and a curved second half-mold. A first extension and a second extension are arranged at the transition from the first half-mold to the second half-mold. Furthermore, the casting mold includes a filling nozzle. This filling nozzle can be used to fill the casting mold with bone cement. The first half-mold and the second half-mold together define a cavity designed for filling with bone cement. The first extension and the second extension together define a cutting area of ​​the body. At this point, the casting mold can be cut open, for example, using a scalpel, to remove the spacers prepared in the casting mold. The cutting area is arranged between the first extension and the second extension. The casting mold also includes a first channel that allows excess bone cement to escape from the cavity of the casting mold.

[0052] Therefore, one embodiment of the present invention relates to a casting mold for preparing an acetabular spacer, the casting mold comprising: a body having a curved first half and a curved second half, a first extension and a second extension, a filling nozzle and a first channel, wherein the first half and the second half together define a cavity, wherein the first extension and the second extension are arranged adjacent to each other on the body and together define a cutting area of ​​the body, wherein the cutting area is arranged between the first extension and the second extension, and wherein the first channel is designed to allow excess bone cement to escape from the cavity of the casting mold.

[0053] The casting mold includes a cavity. This cavity is essentially formed by a first half-mold and a second half-mold. The cavity may have a smooth surface. In one embodiment, both the first and second half-molds have completely smooth inner surfaces. In some embodiments, the casting mold is designed to produce a spacer with a surface texture. For this purpose, the inner surfaces of the first half-mold and / or the second half-mold may exhibit corresponding textures. Examples of such textures include ribs, knobs, and recesses. This textured surface can, for example, facilitate the fixation of the acetabular spacer in a patient's hip joint. Therefore, specifically, it may be advantageous for the first half-mold to include an inner surface with such a texture.

[0054] The casting mold may contain plastic material. The casting mold may be made wholly or partially of plastic material. This allows for cost-effective fabrication, for example, by injection molding. For example, the first and second half-molds may each be individually fabricated from plastic material in an injection molding process and then welded or fused together. In some embodiments, the casting mold is formed as a single piece. In some designs, the casting mold does not contain parting lines, which may result in flash in the spacers fabricated therein. In some embodiments, the first half-mold is fixedly attached to the second half-mold. In some embodiments, the first half-mold is seamlessly attached to the second half-mold. Specifically, the cutting areas of the casting mold may contain plastic material. This allows for easy cutting of the casting mold along the cutting areas. In some embodiments, the plastic material is a thermoplastic. Examples of available plastic materials include polyethylene and polypropylene. Plastics with low density (such as LD-PE) are particularly preferred. Preferably, the plastic material has a density of less than 0.94 g / cm³ at 1 bar and 25°C. 3 The density.

[0055] The cutting area preferably extends circumferentially around the body of the casting mold. In one embodiment, the cutting area extends at least half the circumference of the body of the casting mold. Preferably, the body of the casting mold has a substantially circular cross-section. Tests have shown that cutting approximately halfway through the casting mold (i.e., cutting the casting mold along half the circumference of the body of the casting mold) is generally sufficient to substantially completely open the casting mold and remove the spacers prepared therein.

[0056] To facilitate cutting the casting mold along the cutting area, it may be advantageous to design the cutting area to have a reduced wall thickness. In one embodiment, the body has a first wall thickness, and the cutting area has a second wall thickness, wherein the first wall thickness is thicker than the second wall thickness. This means that the cutting area can have a reduced wall thickness compared to the rest of the casting mold body.

[0057] In one embodiment, the first and second extensions are designed to guide a scalpel along the cutting area to cut through the casting mold. For this purpose, the user of the casting mold can guide the scalpel along the cutting area between the first and second extensions to cut the casting mold. The first and second extensions prevent the user from slipping and injuring themselves while guiding the scalpel. Similarly, as illustrated above, the first and second extensions may extend circumferentially around the body of the casting mold. Preferably, the first and second extensions extend around at least half of the circumference of the body.

[0058] To facilitate opening the casting mold, the first extension and / or the second extension may include tabs. In one embodiment, the first extension includes tabs. In another embodiment, the second extension includes tabs. Preferably, both the first and second extensions each include tabs. This makes it easier to manually pull apart the first and second mold halves. For this purpose, the user of the casting mold can grasp the tabs by hand, thereby separating the first and second mold halves and pulling the two tabs apart. The spacer prepared in the casting mold can then be easily removed.

[0059] In one embodiment, the first extension and / or the second extension extends outward from the body by at least 2 mm. This makes it easier for the user of the device to guide the scalpel along the cutting area to cut through the casting mold. In one embodiment, the first extension extends outward from the body by at least 2 mm. In one embodiment, the second extension extends outward from the body by at least 2 mm. In one embodiment, both the first and second extensions extend outward from the body by at least 2 mm. In some embodiments, the first extension and / or the second extension extends outward from the body by at least 3 mm, 4 mm, 5 mm, or 6 mm.

[0060] In some embodiments, the first extension and / or the second extension extends circumferentially around at least half the circumference of the body. This allows the user of the device to safely guide the scalpel along the cutting area around at least half the circumference of the body to adequately cut the casting mold, allowing easy removal of the spacer prepared therein from the casting mold. In one embodiment, the cutting area extends circumferentially around at least half the circumference of the body.

[0061] In some embodiments, the cutting area has a reduced wall thickness. In some embodiments, the cutting area has a wall thickness of up to 1 mm, preferably up to 0.5 mm or up to 0.4 mm. This allows the user of the casting mold to cut the mold at the cutting area with minimal effort. This helps prevent injury because less force is required and the scalpel is less likely to slip. Furthermore, it reduces the likelihood of damaging the scalpel and / or the spacers contained within the mold when cutting it.

[0062] In some embodiments, the casting mold includes means for cutting off the gate. The means for cutting off the gate may preferably include a movable element. The movable element may include a channel, specifically a first channel as described herein or a second channel as described herein. The movable element may include a protrusion, specifically a first protrusion as described herein or a second protrusion as described herein.

[0063] In some embodiments, the casting mold includes a plug. The plug may be designed to seal the filling nozzle. The plug preferably has a diameter smaller than the diameter of the filling nozzle. The plug is preferably rotatably insertable into the filling nozzle. This means that the plug can still rotate in its sealed filling nozzle state without opening the casting mold. The first channel described herein may preferably be arranged in the plug. Therefore, the plug does not completely hermetically seal the filling nozzle, but allows excess bone cement to flow out of the casting mold when the plug is pressed into the filling nozzle.

[0064] The casting mold includes a filling nozzle. The filling nozzle may have a substantially cylindrical shape. The filling nozzle can be closed by a plug in the casting mold. The filling nozzle may include a stop to limit the penetration depth of the plug into the filling nozzle. The stop may conveniently be designed as a tapered portion of the filling nozzle. Therefore, the filling nozzle may include a neck that is designed as a tapered portion of the cylindrical basic shape of the filling nozzle.

[0065] The first channel described herein preferably defines an entry point through which the cavity of the casting mold can be filled with bone cement. This entry point preferably forms the only location in the casting mold where the spacer produced includes a gate with a width greater than 1 mm. The design described herein allows for minimization or even complete prevention of this gate's formation, or the gate can be eliminated through appropriate design of the casting mold. This allows for the production of spacers without a gate or with only a small gate, where such a small gate is easily removable.

[0066] In one embodiment, the casting mold is designed and configured to cut off the gate using a movable element of the casting mold. The movable element may include a channel or a protrusion. The movable element may be arranged in a plug of the casting mold or in a filling nozzle of the casting mold.

[0067] In one embodiment, the casting mold is designed and configured to cut off the gate by rotational movement of a plug relative to the filling nozzle. As described herein, this functionality can be achieved through different designs. For example, the plug may have a substantially cylindrical shape. A first channel may be eccentrically arranged in the plug, i.e., the first channel may be arranged off-center from the central axis of the plug. In this embodiment of the casting mold, if the plug is rotated while the casting mold is filled with bone cement via the filling nozzle, the gate may be cut off. This means that the bone cement in the cavity of the casting mold is no longer connected to the bone cement in the first channel.

[0068] Furthermore, the plug may include a first protrusion for cutting off the gate. In one embodiment, the first protrusion is disposed within the internal space of the plug. The first protrusion is preferably disposed at the first channel. The first protrusion can be used to apply pressure to the cementitious material to cut off the gate, as explained above. Additionally, the first protrusion may include a beveled cutting edge. This allows the first protrusion to more easily cut through the gate in a knife-like manner. The cutting edge reduces the area of ​​the first protrusion that can be pressed against the gate when the plug rotates. This means that the force associated with the rotation of the plug is applied to the gate over a smaller area.

[0069] In this context, "first channel" and "first protrusion" preferably refer to elements arranged in the plug of the casting mold. In contrast, "second channel" and "second protrusion" preferably refer to elements arranged in the filling nozzle of the casting mold.

[0070] The features and functions mentioned in this paper in conjunction with the first protrusion can also be applied in a corresponding manner to the second protrusion explained below. Consider all embodiments, where the corresponding features may exist only in the first protrusion, only in the second protrusion, or in both. For example, both the first and second protrusions may each include a beveled cutting edge. These two cutting edges can work together, causing them to move relative to each other like scissors, and together they can cause the gate to be cut off.

[0071] Similarly, the casting mold may include a first channel and a second channel, each designed and arranged linearly relative to each other in a first configuration of the casting mold and offset from each other in a second configuration of the casting mold. This allows for control of the permeability of the filling nozzle for bone cement and, on the other hand, allows for gate cutoff. For this purpose, the first channel and / or the second channel may be arranged eccentrically. Furthermore, the first protrusion and / or the second protrusion may be arranged eccentrically. "Eccentric" in the context of the first channel and / or the first protrusion refers to the central axis of the plug, and in the context of the second channel and / or the second protrusion refers to the central axis of the filling nozzle.

[0072] In one embodiment, the casting mold includes a second protrusion for cutting off the gate. In some embodiments, as described above, the casting mold may include a first protrusion and an additional second protrusion. In one embodiment, the casting mold is designed and configured to cut off the gate by rotational movement of the plug relative to the filling nozzle when the first protrusion rotates relative to the second protrusion. For this purpose, as described above, the first protrusion may preferably be arranged on the plug. The first protrusion may be arranged on the plug, preferably in the plug. The second protrusion may be arranged on the plug, preferably in the plug. The first protrusion may be eccentrically arranged on the plug. The second protrusion may be eccentrically arranged on the filling nozzle.

[0073] Furthermore, the plug and / or filling nozzle may each include multiple channels. In one embodiment, the plug includes two first channels. In one embodiment, the filling nozzle includes two second channels.

[0074] In one embodiment, the plug includes a plurality of channels designed and arranged in a point-symmetric manner. In one embodiment, the filling nozzle includes a plurality of channels designed and arranged in a point-symmetric manner. In one embodiment, both the plug and the filling nozzle each include a plurality of channels designed and arranged in a point-symmetric manner.

[0075] In one embodiment, the filling nozzle includes a plurality of channels, wherein the total area of ​​the plurality of channels is at least 30% of the internal cross-sectional area of ​​the filling nozzle.

[0076] In one embodiment, the plug includes a plurality of channels, wherein the total area of ​​the plurality of channels is at least 30% of the internal cross-sectional area of ​​the plug. The “internal cross-sectional area” is derived from the minimum net width of the particular element.

[0077] In some embodiments, the multiple channels of the plug and the multiple channels of the filling nozzle are each designed in the same manner. For example, the plug may include two channels, each with a triangular cross-section, wherein the vertices of the two triangular cross-sections are in contact or nearly in contact with each other. The filling nozzle may also include a second channel, each with a triangular cross-section, wherein the vertices of the two triangular cross-sections are in contact or nearly in contact with each other. By rotating the plug, the channels mentioned above can be aligned in a first configuration of the casting mold, allowing bone cement to be introduced into the cavity of the casting mold through the filling nozzle. By further rotating the plug, the channels mentioned above can be offset from each other, so that no bone cement can pass through the filling nozzle. Thus, the user of the equipment can switch between an open state and a closed state of the casting mold by rotating the plug. This can also be used to remove the gate, as described herein. In this case, if desired, the first and second protrusions can be rotated in opposite directions.

[0078] In other embodiments of the invention, this functionality can also be achieved without a plug. In one embodiment, the casting mold includes an actuating element designed and configured to move the channels and / or protrusions described herein to cut off the gate. In another embodiment, the casting mold includes an actuating element that is accessible from outside the casting mold and is designed and configured to cut off the gate.

[0079] The operating element can be designed and configured to switch between an open state and a closed state of the casting mold, similar to the description above. The operating element is preferably arranged on the filling nozzle. Preferably, the operating element is externally accessible, allowing a user of the casting mold to operate it externally to perform its function. In one embodiment, by connecting a dispensing device for bone cement to the casting mold according to the invention, the operating element is designed and configured to allow the casting mold to enter a first configuration in which bone cement can be introduced into the casting mold. For this purpose, a channel is arranged using the operating element as described herein, allowing bone cement to enter the casting mold through the filling nozzle.

[0080] In some embodiments, the filling nozzle includes a second protrusion for cutting off the gate. In some embodiments, the plug includes a first protrusion for cutting off the gate, and the filling nozzle includes a second protrusion for cutting off the gate. In some embodiments, the casting mold is designed and configured to cut off the gate by rotational movement of the plug relative to the filling nozzle when the first protrusion rotates relative to the second protrusion.

[0081] In some embodiments, the filling nozzle includes a second channel. In some embodiments, the plug includes a first channel, and the filling nozzle includes a second channel, wherein the casting mold is designed and configured to arrange the first channel along an axis common to the second channel in a first rotational position of the plug, and to arrange the first channel off-axis from the second channel in a second rotational position of the plug.

[0082] In some implementations, the casting mold is designed and configured to switch between an open state and a closed state by rotating the mold plug or by rotating an operating element.

[0083] In some implementations, the casting mold is designed and configured to cut off the gate by rotating the mold plug or by rotating the operating element.

[0084] The casting mold may also include one or more venting openings. These venting openings allow the cavity of the casting mold to be completely or almost completely filled with bone cement. This prevents air bubbles from being incorporated into the spacers that can be prepared in the casting mold. The venting openings are preferably arranged between the first and second mold halves. Multiple venting openings may be arranged between the first and second mold halves. These multiple venting openings may be arranged circumferentially around the casting mold at regular intervals between the first or second mold halves. The venting openings may be arranged opposite to the filling nozzle. Multiple venting openings arranged opposite to the filling nozzle may be present. One or more venting openings preferably have a diameter of less than 1.0 mm.

[0085] In this context, "bone cement" refers both to "bone cement dough" (a ductile substance that can harden into a solid, non-deformable material) and to the corresponding hardened bone cement.

[0086] Similarly, the term "gate" herein refers to deformable or hardening bone cement that forms an undesirable structure on a spacer prepared in a casting mold. Such a gate may be formed on the feed line leading to the cavity of the casting mold, particularly in the region of the first channel and / or the second channel described herein.

[0087] In many cases, commercial bone cement is supplied as a kit containing liquid and solid components. By mixing the liquid and solid components, the user can prepare a bone cement dough that can be easily molded within a finite time. Shortly after mixing, the bone cement dough becomes non-sticky, i.e., it no longer adheres to a glove if it comes into slight contact with the glove (as defined in ISO 5833:2002). In this state, preferably, the bone cement dough can be inserted into a casting mold according to the invention for preparing spacers, for example, using a stirring spatula or preferably a suitable dispensing device. Commercial bone cement is typically based on polymethyl methacrylate (PMMA). The casting mold according to the invention is preferably used with this PMMA bone cement. However, other types of bone cement can also be used in principle.

[0088] The present invention also relates to the use of the casting mold described herein for the preparation of acetabular spacers. For this purpose, the casting mold can be filled with bone cement as described herein, and the bone cement can be hardened within the casting mold to prepare a solid acetabular spacer. The casting mold can then be opened as described herein, and the prepared acetabular spacer can be removed from the casting mold.

[0089] The present invention also relates to a method for manufacturing an acetabular spacer. The casting mold described herein can be used for this purpose. The method may include the following steps:

[0090] Provide the casting mold described in this article;

[0091] The casting mold was filled with bone cement.

[0092] The bone cement is hardened in the casting mold;

[0093] Cut open the main body of the casting mold in the cutting area;

[0094] Separate the first half of the mold from the second half; and

[0095] Remove the prepared acetabular spacer from the cut casting mold.

[0096] As described herein, the method may also include removing any gates formed by the bone cement.

[0097] In principle, the steps of the method described above can be performed in any order. In one implementation, the method is performed in the sequence shown above.

[0098] Another aspect of the invention is a spacer that can be prepared using the casting mold described herein.

[0099] Example

[0100] The invention will be further illustrated below with examples, but these examples should not be construed as limiting. It will be apparent to those skilled in the art that other equivalent means may be used in place of the features described herein.

[0101] Attached Figure

[0102] Figure 1A cross-section of a first embodiment of the invention is shown by way of example. A casting mold 100 includes a body 110 comprising a curved first half-mold 111 and a curved second half-mold 112. The first half-mold 111 has a convex outer surface. The second half-mold 112 has a concave outer surface. The first half-mold 111 and the second half-mold 112 together form an inner cavity 115. This cavity 115 is designed to be filled with bone cement and corresponds to the shape of the acetabular spacer to be prepared. To fill the cavity 115, the casting mold 100 includes a filling nozzle 120 disposed on the first half-mold 111. In this case, the filling nozzle 120 has a substantially cylindrical shape to allow for a forced locking connection with a dispensing device. The filling nozzle 120 includes a neck 124, which is designed as a tapering portion of the cylindrical basic shape of the filling nozzle 120. The neck 124 prevents the dispensing device from penetrating too deeply into the casting mold, thereby preventing interruption of the molding process. The neck 124 forms a stop, preventing the dispensing device from entering the cavity 115 between the first half-mold 111 and the second half-mold 112 beyond the filling nozzle 120. The casting mold 100 also includes a first extension 113 and a second extension 114, which are arranged adjacent to each other on the body 110 and extend outwardly from the body 110. Each extension includes a tab, allowing it to be gripped by the user. The first extension 113 and the second extension 114 together define a central cutting region 116 of the casting mold. This cutting region 116 is designed to have a thinner wall compared to the rest of the body, allowing it to be easily cut with a scalpel. The first extension 113 and the second extension 114 can be used here to guide the movement of the scalpel. This prevents the scalpel from slipping, thus ensuring that the casting mold 100 can be opened without causing injury. The casting mold 100 also includes a plug 130 designed to close the filling nozzle 120. Here, the plug 130 is connected to the body 110 of the casting mold via a connector 134. In this way, the plug 130 is continuously held on the casting mold 100, and thus avoids, for example, the plug 130 potentially falling off and thus becoming non-sterile. The plug 130 includes a first channel 131, which is designed to create a connection with the cavity 115. When the casting mold is closed with the plug 130 after being filled with bone cement, excess bone cement can flow out of the casting mold 100 using the first channel 131. The first channel 131 has a small diameter, for example, 2 mm or less, such that only a very small bone cement gate is created, which can be easily removed. In the embodiment shown here, the first channel 131 is concentric, i.e., arranged along the central axis of the plug 130.

[0103] Figure 2A cross-section of one embodiment of the plug 130 is shown by way of example. The plug 130 includes a first channel 131 and a first protrusion 132. At the edge of the protrusion pointing towards the first channel 131, the protrusion 132 has a beveled shape forming a cutting edge 133. The first channel 131 is not arranged centered on the central axis of the plug 130, but rather at an off-center position on the plug. This design of the plug 130 allows the gate made of bone cement to be cut off by rotating the plug 130 in the filling nozzle 120. In this process, the moving cutting edge 133 of the first protrusion 132 cuts through the gate. In this embodiment, it may be meaningful to use a plug 130 without a connector 134 to allow free rotation of the plug 130.

[0104] Figure 3 A cross-section of another embodiment of the invention is shown by way of example. A casting mold 100 includes interconnected first half-mold 111 and second half-mold 112. A filling nozzle 120 is arranged on the first half-mold 111, the filling nozzle including a second channel 121 and a second protrusion 122. The second channel 121 and the second protrusion 122 may exist as alternatives to or supplements to the first channel 131 and the first protrusion 132. The second channel 121 and the second protrusion 122 define the cross-sectional area of ​​the bone cement to be received in the casting mold. This allows for the formation of a thinner bone cement gate at the relevant location, which can be easily removed.

[0105] Figure 4 Another embodiment of the invention is illustrated by way of example. The casting mold 100 shown here includes a first extension 113 and a second extension 114, each including a tab, and thus easily grasped by a user to separate the first half 111 from the second half 112 after the casting mold has been cut open, and to remove the spacers formed therein from the casting mold. The embodiment shown here includes a filling nozzle 120 having a second protrusion 122 operatively connected to an operating element 117. The operating element 117 is externally accessible and allows the protrusion 122 to move within an internal portion of the filling nozzle 120. Movement of the protrusion 122 allows the gate to be cut off from the spacers formed in the casting mold. The filling nozzle 120 also has internal threads 123 for connection to a bone cement dispensing device. As explained herein, the operating element 117 may be designed and configured to enter a first position when connected to the dispensing device, allowing bone cement to be received into the casting mold. Furthermore, the operating element 117 may be designed and configured to cut off the gate made of bone cement by moving the operating element 117 to a second position. In some embodiments, in this second position of the operating element 117, the protrusion 122 closes the filling nozzle 120, so that no more bone cement can flow through the filling nozzle 120.

[0106] Figure 5 A casting mold filled with bone cement 200 according to the invention is shown by way of example. Cavity 115 is completely filled with bone cement 200. By sealing the casting mold with plug 130, a slight overpressure is created on the received bone cement 200, allowing excess bone cement 200 to be released from cavity 115 to the outside through first channel 131. This creates a thin gate 201, the thickness of which is substantially determined by the diameter of first channel 131. After the bone cement 200 has hardened, the thin gate 201 can be easily removed from the acetabular spacer prepared in the casting mold. To remove the spacer from the casting mold, the casting mold must be opened. For this purpose, after the bone cement has hardened, the casting mold can be cut along circumferential cutting area 116 with a scalpel 300. This allows the first half mold 111 to be separated from the second half mold 112. Here, the first extension 113 and the second extension 114 (each of which includes a tab) can be pulled apart by the user to separate the first half mold 111 from the second half mold 112.

[0107] Figure 6 A casting mold according to the invention is shown by way of example, wherein the first half mold 111 has been separated from the second half mold 112, as previously described. The two half molds can be manually pulled apart by grasping the first extension 113 and the second extension 114 to remove the spacer 202 from the casting mold.

[0108] Figure 7 Details of the casting mold are shown, such as those related to... Figure 4 As explained, the casting mold includes a filling nozzle 120 with an operating element 117. The operating element 117 is here in a first position, which allows bone cement to flow through the filling nozzle 120. This first position of the operating element 107 is marked "on" to indicate to the user of the casting mold that, in this configuration of the casting mold, bone cement can be injected into the casting mold.

[0109] Figure 8 It shows that according to Figure 7 Details of the casting mold are shown, with the operating element 117 in a first position. Here, the casting mold includes a first channel 131 and a second channel 121, which, in the first position of the operating element 117, are arranged along a common axis, thereby allowing bone cement to flow through the filling nozzle 120. Furthermore, the casting mold includes a first protrusion 132 and a second protrusion 122, which, in the first position of the operating element 117, are aligned along a common axis.

[0110] Figure 9 Details of the casting mold are shown, such as those related to... Figure 4As explained, the casting mold includes a filling nozzle 120 with an operating element 117. The operating element 117 is here in a second position, which prevents bone cement from flowing through the filling nozzle 120. This second position of the operating element 107 is marked "off" to indicate to the user of the casting mold that the casting mold is completely closed in this configuration, so that no bone cement can flow through the filling nozzle 120.

[0111] Figure 10 It shows that according to Figure 9 The details of the casting mold are shown, with the operating element 117 in a second position. Here, the casting mold includes a first channel 131 and a second channel 121, which, in the second position of the operating element 117, are arranged offset from each other, i.e., not along a common axis. Therefore, the first channel 131 is isolated from the second channel 121. Consequently, no bone cement can pass through the filling nozzle 120. Furthermore, the casting mold includes a first protrusion 132 and a second protrusion 122, which, in the second position of the operating element 117, are also arranged offset from each other.

[0112] By moving the first protrusion 132 relative to the second protrusion 122, the flow of bone cement into the filling nozzle 120 is first blocked, and then the still-extensible gate of the bone cement is cut off. This prevents or at least significantly reduces gate formation.

[0113] Figure 11 A casting mold 100 according to the invention is shown, having an operating element 117 and a dispensing device 400 for bone cement, which is arranged for connection to the casting mold 100. The dispensing device 400 has a thread 401 that engages with a corresponding thread on a filling nozzle 120. The embodiment of the casting mold 100 shown here is designed and configured such that when the dispensing device 400 is screwed into the filling nozzle 120 of the casting mold 100 via the thread 401, the operating element 117 is moved to a first position. Thus, when the dispensing device 400 is screwed into the casting mold 100, the casting mold 100 automatically enters a state that allows bone cement from the dispensing device 400 to be received into the casting mold 100.

[0114] List of reference numerals in the attached figures

[0115] 100 casting molds

[0116] 110 main body

[0117] 111 First Half Model

[0118] 112 First Half Mold

[0119] 113 First Extension

[0120] 114 Second Extension

[0121] 115 chambers

[0122] 116 Cutting Area

[0123] 117 Operating Elements

[0124] 118 exhaust opening

[0125] 120 filling nozzle

[0126] 121 Second Channel

[0127] 122 Second protrusion

[0128] 123 thread

[0129] 124 neck

[0130] 130 plug

[0131] 131 First Channel

[0132] 132 First protrusion

[0133] 133 cutting edge

[0134] 134 connector

[0135] 200 bone cement

[0136] 201 gate

[0137] 202 spacer

[0138] 300 scalpels

[0139] 400 distribution equipment

[0140] 401 thread.

Claims

1. A casting mold (100) for preparing an acetabular spacer, the casting mold comprising a body (110) having a curved first half-mold (111) and a curved second half-mold (112), a first extension (113) and a second extension (114), a filling nozzle (120) and a first channel (131), wherein the first half-mold (111) together with the second half-mold (112) defines a cavity (115), wherein the first extension (113) and the second extension (114) are arranged adjacent to each other on the body (110) and together define a cutting region (116) of the body (110), wherein the cutting region (116) is arranged between the first extension (113) and the second extension (114), and wherein the first channel (131) is designed to allow excess bone cement (200) to escape from the cavity (115) of the casting mold (100).

2. The casting mold according to claim 1, wherein the body (110) has a first wall thickness that is thicker than the second wall thickness of the cutting region (116).

3. The casting mold according to any one of the preceding claims, wherein the first extension (113) and the second extension (114) are designed to guide a scalpel along the cutting area (116) to cut through the casting mold (100).

4. The casting mold according to any one of the preceding claims, wherein the first extension (113) and / or the second extension (114) includes tabs to facilitate manual pulling apart the first half mold (111) and the second half mold (112).

5. The casting mold according to any one of the preceding claims, wherein the first extension (113) and / or the second extension (114) extend outward from the body (110) by at least 2 mm, more preferably at least 3 mm, 4 mm, 5 mm or 6 mm.

6. The casting mold according to any one of the preceding claims, wherein the first extension (113) and / or the second extension (114) extend circumferentially around at least half of the circumference of the body (110).

7. The casting mold according to any one of the preceding claims, the casting mold further comprising means for cutting off the gate, wherein the means preferably comprises a movable element, wherein the movable element is further preferably selected from channels (121, 131) and protrusions (122, 132).

8. The casting mold according to any one of the preceding claims, the casting mold further comprising a plug (130) for closing the filling nozzle (120), wherein the first channel (131) is preferably arranged in the plug (130).

9. The casting mold according to claim 8, wherein the casting mold (130) is designed and configured to cut off the gate (201) by rotational movement of the plug (130) relative to the filling nozzle (120).

10. The casting mold according to any one of claims 8 or 9, wherein the plug (130) includes a first protrusion (132) for cutting off the gate (201), wherein the first protrusion (132) is preferably arranged at the first channel (131).

11. The casting mold according to claim 10, wherein the first protrusion (132) includes a beveled cutting edge (133).

12. The casting mold according to any one of claims 8 to 11, wherein the filling nozzle (120) includes a second protrusion (122) for cutting off the gate (201), wherein the casting mold preferably further includes a first protrusion (132) according to claim 10, and wherein the casting mold is preferably designed and configured to cut off the gate (201) by rotational movement of the plug (130) relative to the filling nozzle (120) when the first protrusion (132) is rotated relative to the second protrusion (122).

13. The casting mold according to any one of claims 8 to 12, wherein the first channel (131) is eccentrically arranged in the plug (130).

14. The casting mold according to any one of claims 8 to 13, wherein the filling nozzle (120) further comprises a second channel (121), wherein the casting mold is designed and configured such that the first channel (131) is arranged along an axis common to the second channel (121) in a first rotational position of the plug, and that the first channel (131) is arranged outside the axis common to the second channel (121) in a second rotational position of the plug.

15. The casting mold according to any one of the preceding claims, the casting mold further comprising an operating element (117) that is accessible from outside the casting mold and is designed and configured to cut off the gate (201).

16. The casting mold according to any one of the preceding claims, the casting mold further comprising an venting opening (118), wherein the venting opening (118) is preferably arranged between the first half mold (111) and the second half mold (112).

17. Use of a casting mold according to any one of the preceding claims for the manufacture of an acetabular spacer.

18. A method for manufacturing an acetabular spacer, the method comprising the following steps: Provide a casting mold according to any one of claims 1 to 16; The casting mold was filled with bone cement; The bone cement is hardened in the casting mold; Remove any gates formed by the bone cement; Cut open the main body (110) of the casting mold in the cutting area (116); Separate the first half mold (111) from the second half mold (112); as well as Remove the prepared acetabular spacer from the cut casting mold.

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