Device and method for making spacers

Abstract

The present invention relates to an apparatus for making a spacer, comprising: a stem mold having an inner space accessible via a proximal opening, the stem mold having a proximal wall that defines the proximal opening at the periphery; a head mold having a hollow space inside, the hollow space having a spherical inner surface and accessible via a distal opening, the head mold having a distal wall that defines the distal opening at the periphery; a metal core having a stem portion, a head portion and a flange, the flange protruding from the metal core, arranged between the stem portion and the head portion and having a proximal surface and a distal surface, wherein the stem mold and the stem portion are shaped so that when the proximal wall abuts against the distal surface, the stem portion is arranged in the inner space, and the head mold and the head portion are shaped so that when the distal wall abuts against the proximal surface, the head portion is arranged in the hollow space. The present invention also relates to a kit having such an apparatus and a method for making a spacer using such an apparatus.

Description

Technical Field

[0001] The present invention relates to a device for making a spacer by solidifying a bone cement paste. The spacer is provided as a temporary placeholder in medical applications for temporary replacement of a joint or a part of a joint including an articulating surface of the joint head. The spacer is preferably suitable for and provided for temporary replacement of a hip joint or a shoulder joint, and is particularly preferably used for temporary replacement of a hip joint. Therefore, the device is preferably used for making a hip joint spacer or a shoulder joint spacer. The present invention also relates to a kit and a method for making such a spacer using such a device.

[0002] Thus, the present invention provides, inter alia, an apparatus for making a one-piece hip and shoulder spacer in the form of a two-piece casting, wherein the casting has a head mold and a stem mold, and a metal core is used to construct the spacer. The hip and shoulder spacers are intended to be temporary placeholders (spacers) for the interim in the case of a two-stage revision of infected total joint hip and shoulder endoprostheses. The present invention is suitable for making hip and shoulder spacers using low-viscosity and high-viscosity polymethylmethacrylate bone cement pastes. Background Art

[0003] Intraarticular prostheses such as hip and shoulder endoprostheses are widely implanted worldwide. Unfortunately, in a few cases, intraarticular prostheses are colonized by microorganisms, particularly Gram-positive bacteria as well as Gram-negative bacteria and to a very small extent yeasts and fungi. These microorganisms, mainly typical skin microorganisms such as Staphylococcus aureus and Staphylococcus epidermidis, may enter the patient's body during surgical operations (OP). Microorganisms may also enter the hematopoietic intraarticular prosthesis. When microorganisms colonize the intraarticular prosthesis, the surrounding bone and soft tissue are also infected and damaged by the microorganisms.

[0004] The prior art mainly includes two methods for treating infected joint endoprostheses, namely, primary suppurative repair and secondary suppurative repair. In the case of primary repair, the infected joint endoprosthesis is first removed, a thorough debridement is performed, and then the repaired joint endoprosthesis is implanted using an OP.

[0005] In a two-stage suppurative repair, in the first OP, the infected intraarticular prosthesis is first removed, followed by debridement and then the spacer is implanted. A hip spacer consists of a handle, a collar, a neck and a ball head, and replicates the hip endoprosthesis in shape and size. Similarly, a shoulder spacer replicates the shoulder endoprosthesis in shape and size. The spacer is anchored to the corresponding bone with bone cement, i.e., in the proximal femur or femoral canal, for example, in the case of a hip spacer. The spacer remains in the patient's body for up to several weeks until the inflammation subsides and clinical inflammatory markers subside. The spacer is then removed in the second OP, and the repair intraarticular prosthesis is implanted after fresh debridement.

[0006] In the case of two-stage suppurative replacement surgery of total joint endoprostheses of hip and shoulder, spacers are of great importance as temporary placeholders in the intermediate stage. During the production of these spacers during surgery, medical personnel add one or more antibiotics specifically suitable for microorganisms to the polymethylmethacrylate bone cement, depending on the available antimicrobial spectrum of the microorganism causing the infection.

[0007] In the case of spacers, antibiotics are added to the cement powder before the actual spacer is made. Using this antibiotic-modified bone cement powder, a bone cement paste is then prepared by mixing a monomer liquid, and the spacer is cast from this bone cement paste, which is then cured by polymerization with the help of the monomer liquid added to the cement powder. The bone cement paste is thus essentially combined with the antibiotic. The antibiotic particles located in the area close to the surface are released under the action of body fluids such as wound secretions. The release of the active ingredient is maximum at the beginning and then decreases over the course of a few days.

[0008] US2010 / 0042213A1 discloses a hip prosthesis having a reservoir for a liquid within the implant. A hip spacer having a groove, into which a substance for treating bones can be introduced, is known from WO2017 / 178951A1. Patent US6245111B1 proposes a hip prosthesis coated with an antibiotic. Patent US5681289 discloses a device for dispensing liquid active ingredients with the aid of an air bag within the device. None of the prostheses are suitable for producing a flushing circuit. EP1991170B1 and US2011 / 0015754A1 describe a hip spacer containing an active ingredient. US2019 / 0290833A1 discloses a flushable hip spacer, with which a liquid circuit can be produced. WO2016 / 205077A1 and US8900322B2 describe other spacers with flushing functions.

[0009] The use of spacers with antibiotics is known. On the one hand, the spacers can be made by the OP personnel during the OP itself from PMMA bone cement powder, antibiotics and a monomer liquid, for example using a spacer mold, as described, for example, in patents DE102015104704B4 or EP2617393B1; on the other hand, the use of industrially prefabricated hip spacers from bone cement is also conventional.

[0010] Plastic castings are conventional for producing spacers with polymethyl methacrylate bone cement during surgery. Plastic castings for making integral hip spacers during surgery are described in US6361731B1. These castings are transparent and have two separate filling openings. Therefore, even high-viscosity bone cement paste can be introduced into the casting with very little pressure because the flow path of the bone cement paste is relatively short. When using non-high-viscosity bone cement paste, once the filling of the casting mold is completed, there is a risk of the bone cement paste flowing back from the filling opening before the start of solidification. These castings are sold with different spacer head diameters. The diameter of the spacer head is not variably adjustable. Medical users can only choose between predetermined spacer head sizes. For medical users, it is ideal to use one casting as much as possible to make the rod so that they can choose between spacer heads of different sizes.

[0011] In a further improvement, patent specifications US7789646B2, US8480389B2 and US8801983B2 propose a multi-component casting mold for making modular hip spacers. These modular hip spacers include a spacer head and a separate rod. For this reason, a casting mold with a spacer head having different diameters of the spacer head can be used. This means that the casting mold for the rod is connected to the casting mold for the spacer head with a selected diameter. The casting mold assembled in this way is then one component and has a thread at the filling opening for connecting the casting mold to the bone cement cartridge. Another variation according to US7637729B2 uses a casting mold for making the rod and a separate casting mold for the spacer head. After completing curing and demoulding, two spacer components are assembled. Patent US7789646B2 describes a modular casting mold, in which the filling opening of the casting mold can be closed with a plug after the cement paste mass is introduced into the casting mold. However, before this, the casting mold must be unscrewed from the bone cement cartridge. Therefore, when using low-viscosity cement paste, if the mold is held in an unfavorable manner, the cement paste may flow out during the separation of the mold from the cement cartridge before the plug is screwed in. Therefore, when using non-high-viscosity cement paste, if the mold is held in an unfavorable manner, the cement paste may flow out during the separation of the mold from the cement cartridge before the plug is screwed in or inserted. In either case, due to the separation of the cement paste from the inner wall of the mold, undesirable entrained air may occur in the spacer mold.

[0012] One problem associated with the listed devices is that the cement dough must have a relatively low viscosity so that the cement dough can flow around the metal core and the casting mold can be completely filled with the cement dough.

[0013] US2007 / 0222114A1 describes a hip spacer mold. The spacer mold comprises a plurality of mold segments connected together. Due to the plurality of segments, the spacer mold can be adapted very precisely to the patient's anatomical environment. The spacer mold segments are connected together by hose clamps driven by a worm screw. PMMA bone cement paste (polymethyl methacrylate bone cement paste) is introduced through a channel in the spacer mold. The complex structure of the casting makes it very complicated to connect the spacer mold segments together and to remove the hip spacer once the curing of the PMMA bone cement paste is completed.

[0014] WO2009 / 073781A2 proposes a spacer mould for a hip spacer, which comprises two parts which can be moved relative to each other so as to be able to adapt to the length of the shaft. Another casting mould is disclosed in EP2522310A1. The device consists of at least two parts, wherein an insertion part is arranged in a first part and an insertion bracket is arranged in a second part. The two parts can be inserted into each other and form a casting mould for making a shaft of a hip spacer. EP2787928A1 describes a complex casting mould. This enables the production of hip spacers with different ball heads. The elements of the casting mould are fixed in place using connecting elements. Summary of the invention

[0015] Therefore, the object of the present invention is to overcome the disadvantages of the prior art. In particular, the object of the present invention is to develop a simple and low-cost device and kit (assembly) for making a one-piece (monolithic) spacer by solidifying a bone cement paste, as well as a method for making a one-piece spacer by solidifying a bone cement paste that can be simply and cost-effectively implemented, using which method medical personnel can use bone cement paste, especially polymethyl methacrylate bone cement paste, to make a one-piece spacer, especially hip (hip) and shoulder spacers during OP. Hip and shoulder spacers have a similar structure. They consist of a rod and a spacer head and a neck connecting the rod and the spacer head. In particular, spacers with different predetermined head diameters and different neck lengths can be made, wherein the offset (neck length) of the spacer to be made, i.e. the distance between the spacer head and the rod, can be individually adjusted by the medical staff on the casting mold.

[0016] The object of the present invention is to be able to use not only low-viscosity but also high-viscosity (polymethyl methacrylate) bone cement paste to produce spacers, in particular hip spacers. In particular, the object of the present invention is to be able to produce spacers with high-viscosity cement paste without using special manual force. The casting mold consists of a maximum of two hollow plastic parts, which can be produced directly and as cheaply as possible, for example by plastic injection molding or by thermoforming plastic films. The casting mold is used to accommodate a metal core of biocompatible metal, which is used to mechanically strengthen the hip spacer. The casting mold to be developed does not have a gate or multiple gates. Therefore, the spacer to be produced should be gateless. Therefore, the present invention avoids costly mechanical post-processing of the produced spacer. In addition, the present invention also relates to a kit or a set of tools, with which spacers, in particular hip spacers, with different head sizes and offsets can be produced according to the specific individual anatomical conditions of the patient. In addition, the present invention describes a method for producing a hip spacer that is as simple as possible.

[0017] The object of the present invention is therefore to develop a device, in particular a device with a casting mould and a metal core, which is in principle suitable for producing hip and shoulder spacers while ensuring the simplest and cheapest construction possible. The object of the present invention is to arrange or have arranged a metal core in the hip and shoulder spacers for the purpose of mechanical stabilization. The object of the present invention is to make it possible to produce spacers using not only low-viscosity or non-high-viscosity but also high-viscosity (polymethyl methacrylate) bone cement pastes. High injection pressures are usually required to completely fill the casting mould with a high-viscosity bone cement paste. It would be helpful if this could be avoided.

[0018] The object of the present invention is achieved by a device for making a spacer by solidifying a bone cement paste, wherein the spacer is provided in the medical field for temporary replacement of a joint or a part of a joint including an articulating surface of a joint head, in particular for temporary replacement of a hip joint or a shoulder joint, the device having:

[0019] A stem mold for forming (molding, shaping) a stem of a spacer from a bone cement paste ball, wherein the stem mold has an interior space in its interior, wherein the interior space is accessible (entered, operated) via a proximal opening on a proximal side of the stem mold, and wherein the stem mold has a proximal wall that peripherally delimits the proximal opening of the stem mold,

[0020] A head mold for forming the head and neck of a spacer from a bone cement paste ball, wherein the head mold has a hollow space in its interior, wherein the hollow space has a spherical inner surface for forming a sliding surface of the head of the spacer, and the hollow space is accessible via a distal opening on a distal side of the head mold, wherein the head mold has a distal wall that peripherally delimits the distal opening of the head mold, and

[0021] a metal core, wherein the metal core has a shaft portion, a head portion and a flange, wherein the flange protrudes from the metal core, wherein the flange is arranged between the shaft portion and the head portion, and wherein the flange has a proximal surface and a distal surface,

[0022] wherein the stem mold and the stem portion of the metal core are shaped so that when the proximal wall of the stem mold rests against the distal surface of the flange, the stem portion is arranged in the interior space of the stem mold, and

[0023] Wherein, the head mold and the head portion of the metal core are shaped such that when the distal wall of the head mold rests against the proximal surface of the flange, the head portion is arranged in the hollow space of the head mold.

[0024] According to the present invention, preferably, the proximal wall of the stem mold can be arranged to be placed flush against the distal surface of the flange, and / or the distal wall of the head mold can be arranged to be placed flush against the proximal surface of the flange.

[0025] Preferably, the stem mould and the stem portion of the metal core are shaped such that the stem portion is completely arranged in the interior space of the stem mould when the proximal wall of the stem mould rests against the distal surface of the flange, in particular rests flush against the distal surface of the flange.

[0026] The head mold and the head portion of the metal core are also preferably shaped so that when the distal wall of the head mold rests against the proximal surface of the flange, in particular rests flush against the proximal surface of the flange, the head portion is completely arranged in the hollow space of the head mold.

[0027] The metal core preferably consists of a biocompatible metal.

[0028] The collar can be formed continuously over the outer circumference or can also have one or more interruptions.

[0029] The device is particularly preferably a device for producing a hip spacer.

[0030] It is contemplated that the metal core may be disposed within the stem mold and the head mold either completely (entirely) or separately from the flange.

[0031] The flange preferably projects laterally or radially from the metal core.

[0032] The proximal surface of the flange limits possible displacement of the head mold in the distal direction of the metal core, and the distal surface of the flange limits possible displacement of the stem mold in the proximal direction of the metal core.

[0033] In a preferred refinement, the flange has the form of a circumferential collar around the metal core, wherein the collar surrounds the metal core annularly or is arranged as an elliptical collar inclined relative to the shank of the metal core. The circumferential collar has the advantage that a firm limit stop of the head mold and the shank mold is provided.

[0034] The directions proximal, distal and lateral are understood to correspond to anatomical direction designations. Distal here means away from the center of the body, while proximal means toward the center of the body. With respect to the spacer and the apparatus for making the spacer, the directional markings are used just as the spacer or the spacer made therewith is positioned in the appropriate state in the patient's body.

[0035] Here, cylinder and cylindrical geometry refer to a general cylinder. This general cylinder is obtained by linearly displacing a base region, which in this case is bounded by the peripheral edge of the cavity. In a straight cylinder, the displacement is carried out perpendicularly to the base region, while in an inclined cylinder, the displacement is carried out at an angle other than 90°.

[0036] According to the invention, the metal core may consist of a stem portion, a head portion and a flange, and / or the metal core may be in one piece.

[0037] In this way, the metal core inside the spacer can better absorb the forces that occur and the device is simple to construct and use.

[0038] It is also conceivable that the shaft mold and / or the head mold consists of a plastic material, and preferably consists of at least one plastic film or of an injection-molded plastic material.

[0039] Like this, this equipment construction cost is low and easy to use.In addition, after use, the shank mould and the head mould can therefore be easily, cheaply and most importantly hygienically processed by incineration.

[0040] In addition, it can be imagined that when the proximal wall of the stem mold rests against the distal surface of the flange, in particular, rests flush against the distal surface of the flange, the stem part is separated from the inner wall of the stem mold that defines the inner space in the interior space of the stem mold, and / or when the distal wall of the head mold rests against the proximal surface of the flange, in particular, rests flush against the proximal surface of the flange, the head part is separated from the inner wall of the head mold that defines the hollow space in the hollow space of the head mold.

[0041] In this way, the metal core can be successfully arranged centrally in the head mold or the shaft mold so that the core is surrounded by a layer of bone cement dough of uniform thickness.

[0042] Furthermore, it is conceivable that the head mold has a neck mold for forming a neck of the spacer from a mass of bone cement, the neck connecting the head and the stem, wherein the neck mold is tubular or hollow cylindrical, wherein the distal opening and the distal wall of the head mold are both part of the neck mold, and the spherical inner surface of the hollow space is not part of the neck mold, wherein the head mold and the head portion of the metal core are preferably shaped such that when the distal wall rests against the proximal surface of the flange, the head portion protrudes beyond the neck mold into the hollow space of the head mold.

[0043] Due to the neck mold, the head mold and thus the device can be used variably to make differently shaped spacers with different neck lengths. The neck mold of the head mold can be shortened straight with scissors, a knife, a scalpel or a saw.

[0044] It is conceivable that the length of the neck mold can be adjusted by shortening the neck mold, wherein preferably a predetermined cutting or tearing point is arranged on the neck mold and / or a scale is arranged on the outside of the neck mold.

[0045] In this way, the device can be used particularly quickly and easily.

[0046] It is also conceivable that the proximal surface of the flange limits the displacement of the metal core in the head mold, in particular in the neck mold, and / or that the distal surface of the flange limits the displacement of the metal core in the stem mold.

[0047] In this way, the flange forms a limit stop for the head mould and / or the stem mould, so that the device can be simply used and assembled.

[0048] According to a preferred embodiment, it is conceivable to provide a centering device on the head of the metal core, wherein the centering device protrudes from the surface of the head part, wherein when the rod part of the metal core is pushed into the hollow space of the head mold, the centering device separates the inner wall of the head mold from the head part, in particular, when the rod part of the metal core is pushed into the hollow space of the head mold, the centering device separates the neck mold wall of the head mold from the head part, wherein the centering device is preferably a centering fin, the head part of the metal core can be axially displaced along the centering fin in the head mold, in particular can be displaced in the neck mold, and / or an isolation member (isolation block, isolation plate) is arranged on the rod part of the metal core, wherein the isolation member protrudes from the surface of the rod part, wherein when the rod part of the metal core is pushed into the internal space of the rod mold, the isolation member separates the inner wall of the rod mold from the rod part of the metal core.

[0049] This ensures that the head portion of the metal core is centered in the head mold and / or the shaft portion of the metal core is centered in the shaft mold and that the cement paste mass can surround these portions on all sides or flow around these portions. This additionally simplifies the assembly of the components of the device during the production of the spacer. The spacer ensures that the metal core is spaced apart from the outside of the shaft to be cast.

[0050] The proximal surface of the flange limits the axial displacement of the head mold in the distal direction of the metal core parallel to the centering device or parallel to the centering fin, and the distal surface of the flange limits the displacement of the stem mold in the proximal direction of the metal core.

[0051] The centering device or the centering fin rests in particular on the inner edge of the hollow cylindrical neck mold of the head mold and centers the head mold so that the axis of the head mold lies on the axis of the proximal metal core. The hollow cylindrical neck mold of the head mold can be shortened manually according to the anatomical requirements of the patient, so that the offset can be adjusted individually. The advantage here is that the spacer neck and the spacer head are thus integral and the two parts of the hip spacer are thus firmly interconnected. No assembly step is required for fastening the spacer head to the neck or stem of the hip spacer as described in patent specifications US7789646B2, US8480389B2 and US8801983B2.

[0052] The centering device and / or the spacer are preferably designed as one component with the metal core. This further simplifies the device.

[0053] Furthermore, it is conceivable that the outer circumference of the flange is larger than the proximal opening of the shaft mold and / or larger than the distal opening of the head mold.

[0054] In this way, the flange can be prevented from being pushed inadvertently and too deeply through the distal opening of the head mold into the hollow space of the head mold, or through the proximal opening of the stem mold into the inner space of the stem mold. This additionally ensures that the axial movement of the distal edge (distal wall) of the head mold relative to the metal core is reliably limited.

[0055] In addition, it is conceivable that at least one vent is arranged in the shaft mold and / or the head mold, wherein the at least one vent connects the interior space of the shaft mold and / or the hollow space of the head mold with the surrounding environment of the device in a gas-permeable manner, wherein the at least one vent is preferably permeable to gas and impermeable to bone cement paste, in particular impermeable to polymethyl methacrylate bone cement paste.

[0056] In this way, it is ensured that the trapped air can escape more easily from the inner space of the stem mold or from the hollow space of the head mold. This prevents the generation of undesirable defects on the surface of the spacer.

[0057] The apparatus may also have cement powder enclosed in at least one bacteria-proof cement container and monomer liquid enclosed in at least one bacteria-proof and liquid-tight monomer liquid container.

[0058] This further completes the device, which is then immediately ready to make spacers.

[0059] It is conceivable that the device has at least one bone cement cartridge, which is used to mix cement powder with monomer liquid and to convey the mixed bone cement paste from the bone cement cartridge. Preferably, the device has such a bone cement cartridge, which is used to mix polymethyl methacrylate bone cement starting components and to convey the mixed polymethyl methacrylate bone cement paste from the bone cement cartridge, wherein it is particularly preferred that the at least one bone cement cartridge has the at least one cement container and accommodates the at least one monomer liquid container, wherein the at least one cement container and the at least one monomer liquid container are arranged in areas separated from each other.

[0060] In this way, the bone cement paste mass made from the bone cement cartridge can be conveniently introduced into the stem mold and the head mold.

[0061] The object of the present invention is also achieved by a kit for making different spacers by solidifying bone cement paste, wherein the spacer is provided in the medical field for temporary replacement of joints or parts of joints including articulating surfaces of joint heads, in particular for temporary replacement of hip joints or shoulder joints, the kit having at least one device according to the present invention as described above, wherein the kit has at least two head molds and / or at least two shaft molds, the head molds having spherical inner surfaces of different diameters, and the shaft molds having hollow spaces of different lengths in the distal direction or hollow spaces of different inner diameters.

[0062] In this way, a variable kit is provided, with which spacers of different shapes suitable for a variety of different treatment situations can be produced.

[0063] It is particularly preferred that the device is a device for producing a hip spacer.

[0064] It is conceivable that the set has at least two metal cores which have different lengths of the head portion and / or lengths of the shaft portion.

[0065] As a result, the suite has a greater number of variables.

[0066] The object of the invention is also achieved by a method for producing a spacer for temporary replacement of a joint or a part of a joint including an articulation surface of the joint head, in particular a hip joint or a shoulder joint, wherein the method is carried out with a device according to the invention or with a kit according to the invention, the method comprising the following steps:

[0067] A) introducing a bone cement paste mass into the inner space of the stem mold, and introducing a bone cement paste mass into the hollow space of the head mold;

[0068] B) pushing the head portion of the metal core into the hollow space of the head mold filled with the bone cement paste ball, thereby displacing the bone cement paste ball contained therein, until the distal wall of the head mold abuts against the proximal surface of the flange of the metal core, and pushing the stem portion of the metal core into the inner space of the stem mold filled with the bone cement paste ball, thereby displacing the bone cement paste ball contained therein, until the proximal wall of the stem mold abuts against the distal surface of the flange of the metal core;

[0069] C) solidifying the bone cement paste in the head mold and the stem mold; and

[0070] D) Removing the resulting shaped and cured spacer from the head and stem moulds.

[0071] Particularly preferably, the method is a method for producing a hip spacer.

[0072] The method preferably does not comprise a step for the treatment or medical treatment of the human or animal body. The method only involves the production of a spacer which can subsequently be used for medical purposes. However, medical use is not carried out during the process according to the invention.

[0073] Step C) is performed after step A) and step B), and step D) is performed after step C). Step A) and step B) may be performed not only sequentially but also in parallel.

[0074] Prior to step A), the neck mold of the head mold can be shortened according to the desired length of the neck of the spacer to be manufactured, a head mold with a spherical inner surface with a matching inner diameter can be selected to match the desired shape of the head of the spacer to be manufactured, a rod mold with an internal space matching the desired shape of the rod of the spacer to be manufactured can be selected, and / or a metal core with a size matching the desired shape of the rod of the spacer to be manufactured can be selected.

[0075] In this way, a variable method is provided, by which spacers of different shapes suitable for a variety of different treatment situations can be produced.

[0076] In addition, it is conceivable that before step A), a homogeneous bone cement paste dough is prepared by mixing a monomer liquid with cement powder, wherein, preferably in step A), the mixed bone cement paste dough is pressed into the interior space of the stem mold and into the hollow space of the head mold using a bone cement cartridge, wherein it is particularly preferred that air is thereby discharged from the interior space of the stem mold and from the hollow space of the head mold.

[0077] This further refines the method.

[0078] It can also be imagined that in step B), the head part of the metal core is centered in the head mold with the help of a centering device, in particular with the help of a centering fin, which protrudes from the head surface and abuts against the inner wall of the hollow space of the head mold when the head part is pushed into the hollow space of the head mold, and / or in step B), the rod part of the metal core is centered in the rod mold with the help of an isolating member, which protrudes from the rod part surface and abuts against the inner wall of the inner space of the rod mold when the rod part is pushed into the inner space of the rod mold.

[0079] This ensures that the head portion of the metal core is centered in the head mold and / or the shaft portion of the metal core is centered in the shaft mold, and the bone cement paste ball can surround these parts on all sides or flow around these parts. This additionally simplifies the assembly of the components of the device during the production of the spacer.

[0080] The present invention is based on the following surprising understanding, that is, head mold and shaft mold can be filled to excessive with bone cement paste mass, and they can be pushed on the metal core with the suitable flange as limit stop, so that excessive bone cement paste mass is pressed out of the casting mold of assembling, and the metal core is partially encapsulated in the bone cement paste mass in the casting mold of assembling.Like this, according to the present invention, can avoid having to be pressed into bone cement paste mass by the gap between the inwall of metal core and head mold and shaft mold, this pressing into particularly needs sizable pressure and the power applied for high viscosity bone cement paste mass.Therefore, head mold and shaft mold can be made by simple plastics low cost again, therefore can simply make, for example by plastic injection molding or by thermoforming plastic film.Before or after the bone cement paste mass solidifies in casting mold, the excessive bone cement paste mass that has occurred from head mold and shaft mold can be removed and discarded.

[0081] According to the present invention, shank mould and head mould can be made by plastic material by injection moulding (injection moulding) at low cost, or even can also be made by thermoforming plastic film, because even during introducing high viscosity bone cement paste mass, they also need not bear any very large power.This is possible, because according to the present invention, bone cement paste mass is introduced in two parts of casting mould, and metal core is not yet arranged therein, and therefore does not have to flow around.It is possible that metal core is arranged in shank mould and head mould after introducing bone cement paste mass, because shank mould and head mould are placed against the flange of metal core, and therefore arrange and be oriented to cooperate with metal core and cooperate with each other.Therefore, shank mould and head mould do not need to be threaded or fastened together in expensive pressure-resistant mode.

[0082] Another particular advantage of the present invention is that, using the head mold, a variable columnar region can be produced, which can be referred to as a neck mold and is used to form the neck of the spacer, which connects the head of the spacer to the stem of the spacer, which is achieved by manually shortening the columnar region according to the anatomical requirements of the specific patient. Different shapes of head molds can be used and selected to make spacers with different head diameters. The kit according to the present invention can also be adapted to other sizes by means of different shapes of stem molds and different shapes of metal cores.

[0083] The device according to the present invention is used in such a way that, first, the bone cement paste mass is retrogradely introduced into the head mold. A mixing system or a cartridge system as a bone cement applicator has a cartridge and a manually operable discharge device that can be used for this purpose. Then the proximal head of the metal core is pressed into the head mold filled with the bone cement paste mass. The proximal head portion of the metal core penetrates into the bone cement paste mass until the distal wall of the edge of the hollow cylindrical neck portion of the head mold or the edge of the head mold contacts the proximal surface of the flange. The flange limits the axial movement of the head mold. Then, the shaft mold is retrogradely filled with the bone cement paste mass. After this, the shaft of the metal core is pressed into the shaft mold filled with the bone cement paste mass until the proximal wall of the edge of the shaft mold stops on the distal surface of the flange. Excessive discharge of the bone cement paste mass appears from the opening of the shaft mold and is manually removed. Then the bone cement paste mass is solidified. After this, the head mold is removed by cutting, and the shaft mold is pulled out of the solidified shaft of the spacer that has been formed. This spacer also can be made with equipment according to the present invention, makes at first fill the shank mould with the bone cement paste mass, fills the head mould then.In this case, the metal core also is pressed into the mould that is filled with bone cement.

[0084] The device according to the invention is based on the surprising discovery that the metal core can be pressed into the casting mold filled with bone cement dough with less force than by pressing the bone cement dough around the metal core arranged in the casting mold by pressure generated by a manually actuated discharge device - which is necessary in the known casting devices according to patent specifications US7789646B2, US8480389B2 and US8801983B2.

[0085] As a result, even without using high pressure, the spacer can be produced in a few minutes from a high viscosity bone cement paste. A pressure-resistant casting mold is not necessary. The casting mold according to the invention is filled practically without pressure and can therefore be produced from a thin plastic film or an injection-molded plastic product.

[0086] An exemplary apparatus according to the invention may include:

[0087] a) a metal core comprising a head portion and a shaft portion, wherein the head portion is separated from the shaft portion by one or more flanges, the flanges being arranged on a surface of the metal core, wherein the at least one flange has a proximal side (surface) and a distal side (surface),

[0088] b) a hollow spacer head mold or a head mold, which is made of plastic material and has a hollow cylindrical neck mold,

[0089] c) a hollow shaft mold made of plastic material, wherein:

[0090] d) When the hollow cylindrical neck mold is abutted against the proximal side of at least one connecting part, the head part of the metal core extends into the inner space of the head mold, and when the shaft part of the metal core is abutted with its opening against the distal side of the at least one flange, the shaft part is completely surrounded by the shaft mold.

[0091] An exemplary kit for making a spacer according to the present invention may include:

[0092] a) a metal core comprising a head portion, a flange and a stem portion,

[0093] b) at least one stem mold, and

[0094] c) At least two head molds with different head diameters, which are arranged in a sterilizable, antibacterial packaging container.

[0095] The kit according to the invention provides the advantage that spacers with different head sizes can be made by a medical user using one packaging unit of the kit. Therefore, there is no need to provide a separate packaging unit for each spacer head size.

[0096] Another exemplary kit for making a spacer according to the present invention may include:

[0097] a) Cement powder packaged in antibacterial containers,

[0098] b) Monomer liquids packaged in sterile and liquid-tight containers,

[0099] c) a metal core comprising a head portion, at least one flange and a shank portion,

[0100] d) at least one stem mold, and

[0101] e) At least two head molds with different head diameters are arranged in a sterilizable, antibacterial packaging container.

[0102] Such a kit may be provided to a medical user as a "surgical kit" which contains all the components required to make a hip spacer.

[0103] An exemplary method according to the invention for making a spacer using the device according to the invention may comprise the following consecutive (continuous) steps:

[0104] a) Mixing cement powder with monomer liquid until a uniform bone cement paste is obtained,

[0105] b) introducing a mass of bone cement into the head mold,

[0106] c) Introduce a mass of bone cement into the rod mold,

[0107] d) pushing the head portion of the metal core into the head mold filled with the bone cement paste ball, thereby displacing the bone cement paste ball, until the edge of the hollow cylindrical neck mold of the head mold abuts against the proximal surface of the flange,

[0108] e) pushing the stem portion of the metal core into the stem mold filled with the bone cement paste ball, thereby displacing the bone cement paste ball, until the proximal opening of the stem mold abuts against the distal surface of the flange,

[0109] f) allowing the bone cement paste to solidify, and

[0110] g) After the bone cement paste has completely cured, remove the head mold and the stem mold.

[0111] According to the invention, it is conceivable that the length of the hollow cylindrical neck mold of the head mold is shortened before step a) in order to adjust the offset, i.e. the distance between the head and the stem of the spacer. To this end, the medical user shortens the hollow cylindrical neck mold on the head mold using scissors or a saw until the desired offset, i.e. the distance from the center of the spherical mold to the longitudinal axis of the metal core, is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0112] More exemplary embodiments of the present invention are explained below with reference to twenty-five schematic diagrams, but the present invention is not limited thereby. In the drawings:

[0113] Figure 1 shows a schematic perspective partial cross-sectional view of a first exemplary assembled apparatus for making a hip spacer according to the present invention;

[0114] Figure 2 Shown according to Figure 1 A schematic perspective external view of a first device assembled according to the present invention;

[0115] Figure 3 Shown according to Figure 1 and 2 A schematic perspective, partially cut-away view of a first device assembled according to the present invention;

[0116] Figure 4 Shown according to Figures 1 to 3 A schematic perspective external view of components of a first device according to the invention;

[0117] Figure 5 shows a schematic partial cross-sectional view of a first device assembled according to the present invention;

[0118] Figure 6 shows a schematic cross-sectional view of a first device according to the invention, into which a bone cement paste dough is introduced;

[0119] Figure 7 shows a schematic side view of a hip spacer made using a first apparatus according to the present invention;

[0120] Figure 8 shows a partial cross-sectional perspective view of a second exemplary assembled apparatus for making a hip spacer according to the present invention;

[0121] Fig. 9 shows a side view of a second device assembled according to the present invention;

[0122] Fig.10 shows a partial cross-sectional view of a second device assembled according to the present invention;

[0123] Fig.11 shows a perspective view of a hip spacer produced using a second apparatus according to the present invention;

[0124] Fig.12 A partial cross-sectional view showing an assembled second apparatus having a shortened neck mold according to the present invention;

[0125] Fig.13 A partial cross-sectional view showing a third apparatus according to the present invention assembled with a smaller head mould;

[0126] Fig.14 shows a partial cross-sectional view of a third device according to the invention during the introduction of a bone cement paste dough for making a spacer;

[0127] Fig.15 shows a partial cross-sectional view of a second device according to the invention, in which a metal core is pushed into a head mold filled with a dollop of bone cement for making a spacer;

[0128] Fig.16 A partial cross-sectional view of a second device according to the present invention is shown, wherein the metal core is completely pushed to the limit stop and enters the head mold filled with a bone cement paste dough for making a spacer;

[0129] Fig.17shows a partial cross-sectional view of a second device according to the invention during the introduction of a bone cement paste dough for making a spacer;

[0130] Fig.18 shows a partial cross-sectional view of a second device according to the present invention, in which a metal core is pushed into a stem mold filled with a dollop of bone cement for making a spacer;

[0131] Fig.19 A partial cross-sectional view of a second device according to the present invention is shown, wherein the metal core is completely pushed to the limit stop into the stem mold filled with bone cement paste for making a spacer;

[0132] Fig. 20 A partial cross-sectional view showing a second assembled device according to the invention filled with a dollop of bone cement during the curing of the dollop of bone cement;

[0133] Fig.21 shows a partial cross-sectional perspective view of a first set of components according to the invention with an exemplary fourth apparatus according to the invention with two different head molds for producing a hip spacer;

[0134] Fig. 22 Shown according to Fig.21 An external perspective view of components of a first device according to the present invention;

[0135] Fig.23 Shown according to Fig.21 and 22 A schematic perspective, partially cut-away view of a fourth device according to the first group of the invention assembled according to the invention;

[0136] Fig.24 A) to H) show schematic cross-sections through eight apparatuses which differ in terms of the head mould for producing a hip spacer which can be used as a kit according to the invention; and

[0137] Fig.25 A) to H) show the use of Fig.24 Schematic side views of spacers made with the devices of A) to H). DETAILED DESCRIPTION

[0138] Figures 1 to 25 The apparatus, kit and components and method sequence for producing a hip spacer are shown. A person skilled in the art can directly transfer this teaching to the apparatus, kit and components and method sequence for making a shoulder spacer.

[0139] Figures 1 to 7 It is shown that the method for making Figure 7The drawings of a first exemplary embodiment of a hip spacer device and various views of components of the device are shown.

[0140] The first device according to the invention is suitable and arranged for making a spacer 38 for a hip joint (see Figure 7 The device comprises a stem mold 1, a head mold 5 and a metal core 10. The stem mold 1 and the head mold 5 are preferably each a one-piece (integral) structure. The stem mold 1 and the head mold 5 can together form a bone cement paste mass 36 (see Figure 6 ) is formed into a two-part casting mold. The bone cement paste mass 36 can be cured in the casting mold for this purpose. Figure 1 , 3 , 5 and 6 show the sectioned stem mold 1 and head mold 5 so that the internal structure of the device is visible. The metal core 10 is only Figure 6 It is shown in a cutaway manner in one figure and in a non-cutaway manner in other figures.

[0141] The stem mold 1 may have an interior space 2 in which a bone cement paste ball 36 may be formed to form the stem portion 42 of the spacer 38. The interior space 2 may be accessible via a proximal opening 3, so that the bone cement paste ball 36 may be introduced into the interior space 2 through the proximal opening 3 of the stem mold 1, and the metal core 10 may be partially pushed into the interior space 2 of the stem mold 1 through the proximal opening 3. Around the proximal opening 3, the stem mold 1 may have a proximal wall 4 that defines and surrounds the proximal opening 3.

[0142] The head mold 5 may have a hollow space 6 in which a bone cement paste ball 36 can be formed to form a head 40 of the spacer 38. On the proximal side of the hollow space 6, the hollow space 6 may have a spherical inner surface 7, which is used to form the actual articular surface of the spacer 38. The spherical inner surface 7 of the hollow space 6 correspondingly shapes the hip articular surface of the spacer 38, which is intended to slide in the hip joint socket. The hollow space 6 can be approached through the distal opening 8, so that the bone cement paste ball 36 can be introduced into the hollow space 6 through the distal opening 8 of the head mold 5, and the metal core 10 can be partially pushed into the hollow space 6 of the head mold 5 through the distal opening 8. Around the distal opening 8, the head mold 5 may have a distal wall 9 that defines and closes the distal opening 8.

[0143] Before being introduced, the bone cement paste 36 may have been mixed with a monomer liquid and cement powder (not shown), wherein at least one antibiotic and / or at least one antifungal agent may also be preferably mixed with the bone cement paste 36. The bone cement paste 36 may be filled into the stem mold 1 and the head mold 5 via a bone cement applicator 132, which is as described with respect to the second exemplary embodiment. Fig.14 and 17 as shown in .

[0144] The metal core 10 can be made of a biocompatible metal such as stainless steel or titanium. The metal core 10 is used to strengthen and thus mechanically stabilize the spacer 38. The metal core 10 has a shaft portion 12, a head portion 14 and a flange 16, which is arranged between the shaft portion 12 and the head portion 14. The metal core 10 is preferably a single component. The shaft portion 12 and the head portion 14 can be connected together by the flange 16. The flange 16 can extend in a radial direction from the axis of the head portion 14 and the shaft portion 12. The extended flange 16 has a proximal surface 18 and an opposite distal surface 20.

[0145] The proximal wall 4 of the stem mold 1 can be shaped to match the distal surface 20 of the flange 16, so that the stem mold 1 can be placed at least partially flush with the distal surface 20 of the flange 16. This allows a determined positioning of the stem mold 1 on the flange 16 of the metal core 10. Similarly, the distal wall 9 of the head mold 5 can be shaped to match the proximal surface 18 of the flange 16, so that the head mold 5 can be placed at least partially flush with the proximal surface 18 of the flange 16. This allows a determined positioning of the head mold 5 on the flange 16 of the metal core 10.

[0146] A plurality of protruding spacers 22 of elongated shape can be arranged on the shaft portion 12, which facilitate the positioning and orientation of the shaft portion 12 in the shaft mold 1 when the shaft portion 12 is pushed through the proximal opening 3 into the shaft mold 1. The height of the spacers 22 is selected here so that when the shaft portion 12 is fully pushed into the shaft mold 1, they abut against the inner wall of the inner space 2 of the shaft mold 1.

[0147] A plurality of protruding centering means 24, for example four protruding fins, can be provided on the head portion 14, which facilitates the positioning and orientation of the head portion 14 in the head mold 5 when the head portion 14 is pushed into the head mold 5 through the distal opening 8. For the same purpose, the head portion 14 can be shaped on its proximal side with a cone 26, which facilitates its pushing into the bone cement paste mass 36. The orientation of the fins is preferably selected so that they can slide along their linear surface into the hollow space 6 of the head mold 5. The head mold 5 can have a neck mold 28 with a cylindrical inner space as part of the hollow space 6. The centering means 24 can slide on the inner wall of the neck mold 28. The height of the centering means 24 is preferably selected here so that they rest on the inner wall of the hollow space 6 of the neck mold 28 of the head mold 5 when the head portion 14 is completely pushed into the head mold 5. The limit stop for this purpose can be formed by the distal wall 9 of the head mold 5 and the proximal surface 18 of the flange 16.

[0148] The neck mold 28 may have a plurality of protruding rings 30 in the form of a peripheral thickening along which the neck mold 28 can be cut and thus shortened. To this end, the rings 30 may be evenly spaced, in particular at even intervals of integer or half-integer centimeters or inches. In this way, the length of the neck 44 of the spacer 38 to be produced, which is determined by the length of the neck mold 28, can be adjusted.

[0149] The flange 16 may have a plurality of protrusions 32, which may protrude in a radial or transverse direction from the flange 16. The protrusions 32 may form the proximal surface 18 and / or the distal surface 20 of the flange 16, or may be part of the proximal surface 18 and / or the distal surface 20 of the flange 16. When the metal core 10 is pushed in, excess bone cement paste 36 may be discharged from the stem mold 1 between the gaps between the protrusions 32, and in theory may also be discharged from the head mold 5.

[0150] A collar portion 34 may be formed on the shank mold 1 , the collar portion surrounding the flange 16 starting from the proximal wall 4 of the shank mold 1 .

[0151] According to the present invention, the shank mold 1 and the head mold 5 can be made of plastic material by injection molding at low cost, or even can also be made of thermoformed plastic film, because even during the introduction of high viscosity bone cement paste mass, they do not have to bear any very large force. This is possible because according to the present invention, the bone cement paste mass 36 is introduced into the shank mold 1 and the head mold tool 5 as a casting mold when the metal core 10 is not yet arranged therein, and therefore must flow around. It is possible to arrange the metal core 10 in the shank mold 1 and the head mold 5 after introducing the bone cement paste mass 36, because the shank mold 1 and the head mold 5 are placed against the flange 16 of the metal core 10, and therefore can be arranged and oriented to cooperate with the metal core 10 and cooperate with each other. Therefore, the shank mold 1 and the head mold 5 do not need to be screwed or fastened together in an expensive, pressure-absorbing and stable manner.

[0152] Once the bone cement paste 36 has solidified on the metal core 10 in the casting mold assembled by the stem mold 1 and the head mold 5, the bone cement paste 36 contained therein can be cured (see Figure 6 ). Subsequently, the obtained spacer 38 can be demoulded by pulling down the rod-shaped mold 1 and separating and disassembling the head mold 5. Figure 7 A spacer 38 is shown in which the metal core 10 is enclosed or mostly enclosed in the spacer 38 to act as a reinforcement. The flange 16 or the protrusion 32 of the flange 16 at the transition from the stem 42 to the neck 44 of the spacer 38 is still evident on the surface of the spacer 38. The outer surface of the spacer 22 in the stem 42 and the outer surface of the centering device 24 in the neck 44 of the spacer 38 are also evident.

[0153] Figures 8 to 12 14 to 20 are diagrams showing the method for making a Fig.11 A second exemplary embodiment of a hip spacer device is shown in the drawings along with various views of components of the device. Fig.13 A third exemplary embodiment is shown which differs from the second exemplary embodiment only in the diameter used to form the joint head but is otherwise identical.

[0154] The second device according to the invention and the third device according to the invention are suitable and provided for making a spacer 88 for a hip joint (see Fig.11 ). The second device according to the present invention has a stem mold 51 and a head mold 55 and a metal core 60. The stem mold 51 and the head mold 55 are preferably each a one-piece structure. The stem mold 51 and the head mold 55 can together form a bone cement paste mass 86 (see Figures 14 to 20 ) is formed into a two-part casting mold. The bone cement paste mass 86 can be cured in the casting mold for this purpose. Figure 8 , 10 , 12 and 14 to 20 show the shank mold 51 and the head mold 55 cut away, so that the internal structure of the device can be seen. The metal core 60 is always shown in an uncut state.

[0155] The stem mold 51 may have an interior space 52 in which a bone cement paste ball 86 may be formed to form the stem portion 92 of the spacer 88. The interior space 52 may be accessible via a proximal opening 53, so that the bone cement paste ball 86 may be introduced into the interior space 52 through the proximal opening 53 of the stem mold 51, and the metal core 60 may be partially pushed into the interior space 52 of the stem mold 51 through the proximal opening 53. Around the proximal opening 53, the stem mold 51 may have a proximal wall 54 that defines and surrounds the proximal opening 53.

[0156] The head mold 55 may have a hollow space 56 in which a cement paste ball 86 may be formed to form a head 90 of the spacer 88. On the proximal side of the hollow space 56, the hollow space 56 may have a spherical inner surface 57, which is used to form the actual articular surface of the spacer 88. The spherical inner surface 57 of the hollow space 56 thus shapes the hip articular surface of the spacer 88, which is intended to slide in the hip socket. The hollow space 56 can be approached through the distal opening 58, so that the cement paste ball 86 can be introduced into the hollow space 56 through the distal opening 58 of the head mold 55, and the metal core 60 can be partially pushed into the hollow space 56 of the head mold 55 through the distal opening 58. Around the distal opening 58, the head mold 55 may have a distal wall 59 that defines and closes the distal opening 58.

[0157] The metal core 60 can be made of a biocompatible metal such as stainless steel or titanium. The metal core 60 is used to strengthen and thus mechanically stabilize the spacer 88. The metal core 60 has a shaft portion 62, a head portion 64 and a flange 66, which is arranged between the shaft portion 62 and the head portion 64. The metal core 60 is preferably a single component. The shaft portion 62 and the head portion 64 can be connected together by the flange 66, and the flange 66 can extend in a radial direction from the axis of the head portion 64 and the shaft portion 62. The extended flange 66 has a proximal surface 68 and an opposite distal surface 70.

[0158] The proximal wall 54 of the stem mold 51 can be formed to match the distal surface 70 of the flange 66, so that the stem mold 51 can be positioned to be at least partially flush with the distal surface 70 of the flange 66, which allows the stem mold 51 to be definitely positioned on the flange 66 of the metal core 60. Similarly, the distal wall 59 of the head mold 55 can be formed to match the proximal surface 68 of the flange 66, so that the head mold 55 can be positioned to be at least partially flush with the proximal surface 68 of the flange 66, which allows the head mold 55 to be definitely positioned on the flange 66 of the metal core 60.

[0159] A plurality of protruding spacers 72 of elongated shape may be provided on the shaft portion 62, which facilitate positioning and orientation of the shaft portion 62 in the shaft mold 51 when the shaft portion 62 is pushed through the proximal opening 53 into the shaft mold 51. The height of the spacers 72 is selected here so that when the shaft portion 62 is fully pushed into the shaft mold 51, they rest against the inner wall of the inner space 52 of the shaft mold 51.

[0160] A plurality of protruding centering means 74, for example four protruding fins, can be provided on the head portion 64, which facilitates the positioning and orientation of the head portion 64 in the head mold 55 when the head portion 64 is pushed into the head mold 55 through the distal opening 58. For the same purpose, the head portion 64 can be shaped as a cone 76 on its proximal side, which is used to facilitate its pushing into the bone cement paste mass 86. The orientation of the fins is preferably selected so that they can slide along their linear surface into the hollow space 56 of the head mold 55. The head mold 55 can have a neck mold 78 with a cylindrical inner space as part of the hollow space 56. The centering means 74 can slide on the inner wall of the neck mold 78. The height of the centering means 74 is preferably selected here so that they rest on the inner wall of the hollow space 56 of the neck mold 78 of the head mold 55 when the head portion 64 is completely pushed into the head mold 55. The limit stops for this purpose may be formed by the distal wall 59 of the head mould 55 and the proximal surface 68 of the flange 66 .

[0161] The neck mold 78 can have a plurality of protruding rings 80 in the form of a peripheral thickening along which the neck mold 78 can be cut and thus shortened. To this end, the rings 80 can be evenly spaced, in particular at even intervals of integer or half-integer centimeters or inches. In this way, the length of the neck 94 of the spacer 88 to be produced, which is determined by the length of the neck mold 78, can be adjusted.

[0162] A collar portion 84 may be formed on the stem mold 51 , the collar portion surrounding the flange 66 starting from the proximal wall 54 of the stem mold 51 .

[0163] According to the present invention, the shaft mold 51 and the head mold 55 can be produced by plastic material by injection molding at low cost, or even can also be produced by the plastic film of thermoforming, because even during the introduction of high viscosity bone cement paste mass, they do not have to bear any very large force. This is possible, because according to the present invention, the bone cement paste mass 86 is introduced into the shaft mold 51 and the head mold 55 as a casting mold, and the metal core 60 is not yet arranged therein, and therefore must flow around. It is possible to arrange the metal core 60 in the shaft mold 51 and the head mold 55 after introducing the bone cement paste mass 86, because the shaft mold 51 and the head mold 55 are placed against the flange 66 of the metal core 60, and therefore can be arranged and oriented to cooperate with the metal core 60 and cooperate with each other. Therefore, the shaft mold 51 and the head mold 55 do not need to be threaded or fastened together in an expensive, pressure-absorbing and stable manner.

[0164] Once the bone cement paste mass 86 in the casting mold assembled by the stem mold 51 and the head mold 55 has solidified on the metal core 60, the bone cement paste mass 86 (see Fig. 20 ) can be cured. Subsequently, the resulting spacer 38 can be demoulded by pulling out the stem mold 51 and separating and removing the head mold 55. Fig.11 A spacer 88 is shown in which the metal core 60 is enclosed or mostly enclosed in the spacer 88 to serve as a reinforcement. The flange 66 at the transition from the stem 92 to the neck 94 of the spacer 88 is still evident on the surface of the spacer 88, as are the outer surfaces of the spacer 72 in the stem 92 and the centering device 74 in the neck 94 of the spacer 88.

[0165] Before being introduced into the stem mold 51 or the head mold 55, the bone cement paste 86 may have been mixed with a monomer liquid and cement powder (not shown), wherein at least one antibiotic and / or at least one antifungal drug may also be preferably mixed with the bone cement paste 86. The bone cement paste 86 may be applied to the stem mold 51 or the head mold 55 by a bone cement applicator 132 (see FIG. Fig.14 and 17) is filled into the stem mold 51 and the head mold 55. Here, the inner space 52 of the stem mold 51 is filled from the distal side, and the hollow space 56 of the head mold 55 is filled from the proximal side to prevent air from being entrained. Vents (not shown) may also be provided in the walls of the stem mold 51 and the head mold 52 to avoid air entrapment.

[0166] Once the bone cement 86 is excessively filled into the stem mold 51 and the head mold 55, the stem portion 62 of the metal core 60 can be pushed into the stem mold 51, and the head portion 64 of the metal core 60 is pushed into the head mold 55. The flange 66 forms a limit stop for both. Any excess bone cement paste 86 that occurs can be removed. The bone cement paste 86 is cured in a state where the metal core 60 is enclosed therein (see Fig. 20 ).

[0167] In order to adapt the spacer 88 to the anatomical environment, the neck 78 can be shortened along the ring 80, such as Fig.12 shown.

[0168] Fig.13 The third exemplary embodiment shown differs from the second exemplary embodiment only in that it has a different head mold 105 with a different radius of the spherical inner surface 107. Due to the different shape of the head mold 105, there are also different hollow spaces 106 in the head mold 105. Similar to the head mold 55, the head mold 105 can have a distal opening 108 and a circumferential distal wall 109. A neck mold 128 with an outer peripheral ring 130 can also be provided. All other parts of the third exemplary embodiment are the same as the second exemplary embodiment. Together with the head mold 55 and the metal core 60 and the stem mold 51, and if necessary also with the bone cement applicator 132, the head mold 105 can take the form of a kit according to the present invention.

[0169] The bone cement applicator 132 may have a barrel 134 for mixing the bone cement paste 86, which—except for the opening—may be closed on the front side by a barrel head 136. In addition, a vacuum port 138 may be arranged on the barrel head 136 so that the bone cement paste 86 can be mixed under vacuum in the interior of the barrel 134. Once fully mixed, the bone cement paste 86 can be squeezed through the opening and into the shaft mold 51 and the head mold 55 (see FIG. 1 ). Fig.14 and 17 ). A static mixer (not shown) can be arranged in the delivery tube 140, by means of which the starting components of the bone cement paste 86 can be mixed. The delivery tube 140 can be fastened to the cartridge head 136 by means of a sleeve nut 142.

[0170] Figure 21-2324A), 24B), 25A) and 25B) are diagrams showing a kit according to the present invention and a kit according to the present invention for making Fig.25 A) and 25B) show various views of a fourth exemplary embodiment of a device for a hip spacer and various views of components of the device. Similar to the combination of different head molds of the second and third exemplary embodiments, the kit has two head molds 155, 205 of different shapes. Fig.24 C) to 24H) and 25C) to 25H) show alternatives of shortened and unshortened head molds 255 with spherical inner surfaces 257 of different radii.

[0171] The kit or fourth device according to the invention is suitable and arranged for making two differently shaped spacers 188, 238 for a hip joint (see Fig.25 A) and 25B)). The device has a stem mold 151 and two head molds 155, 205 and a metal core 160. The stem mold 151 and the head mold 155, 205 are preferably each of a one-piece construction. The stem mold 151 and the head mold 155, 205 can together form two two-part casting molds for shaping the bone cement paste mass introduced therein (not shown, but similar to Figure 6 and 20 ). For this purpose, the bone cement dough can solidify in the casting mold. Fig.21 , 23 24 show the sectioned stem mold 151 and the head mold 155, 205 so that the internal structure of the device can be seen. The metal core 160 is always shown in an unsectioned state.

[0172] The stem mold 151 may have an interior space 152 in which a mass of bone cement may be formed to form the stems 192, 242 of the spacers 188, 238. The interior space 152 may be accessible via a proximal opening 153, such that a mass of bone cement may be introduced into the interior space 152 through the proximal opening 153 of the stem mold 151, and the metal core 160 may be partially pushed into the interior space 152 of the stem mold 151 through the proximal opening 153. Around the proximal opening 153, the stem mold 151 may have a proximal wall 154 that defines and closes the proximal opening 153.

[0173] The head mold 155, 205 may have a hollow space 156, 206 in which a mass of bone cement may be formed to form the head 190 of the spacer 188. On the proximal side of the hollow space 156, 206, each of the hollow spaces 156, 206 may have a spherical inner surface 157, 207, which is used to form the actual joint surface of the spacer 188, 238. The spherical inner surface 157, 207 of the hollow space 156, 206 correspondingly forms the hip joint surface of the spacer 188, 238, which is intended to slide in the hip joint socket. The hollow space 156, 206 is accessible via the distal opening 158, 208, so that the bone cement paste ball can be introduced into the hollow space 156, 206 through the distal opening 158, 208 of the head mold 155, 205, and the metal core 160 can be partially pushed into the hollow space 156, 206 of the head mold 155, 205 through the distal opening 158, 208. Around the distal opening 158, 208, the head mold 155, 205 can each have a distal wall 159, 209 that defines and closes the corresponding distal opening 158, 208.

[0174] Prior to introduction, the bone cement paste may have been mixed from a monomer liquid and cement powder (not shown), wherein at least one antibiotic and / or at least one antifungal agent may also preferably be mixed with the bone cement paste. The bone cement paste may be filled into the shaft mold 151 and the head mold 155, 205 via the bone cement applicator 132, as described with respect to the second exemplary embodiment. Fig.14 and 17 as shown in .

[0175] The metal core 160 can be made of a biocompatible metal, such as stainless steel or titanium. The metal core 160 is used to strengthen the spacer 188, 238 and thus mechanically stabilize the spacer. The metal core 160 has a shaft portion 162, a head portion 164 and a flange 166, which is arranged between the shaft portion 162 and the head portion 164. The metal core 160 is preferably one-piece. The shaft portion 162 and the head portion 164 can be connected together by the flange 166. The flange 166 can protrude in a radial direction from the axis of the head portion 164 and the shaft portion 162. The protruding flange 166 has a proximal surface 168 and an opposite distal surface 170.

[0176] The proximal wall 154 of the stem mold 151 can be shaped to match the distal surface 170 of the flange 166, so that the stem mold 151 can be at least partially placed flush with the distal surface 170 of the flange 166. This allows for a definite positioning of the stem mold 151 on the flange 166 of the metal core 160. Similarly, the distal wall 159, 209 of the head mold 155, 205 can be shaped to match the proximal surface 168 of the flange 166, so that the head mold 155, 205 can be at least partially placed flush with the proximal surface 168 of the flange 166. This allows for a definite positioning of the head mold 155, 205 on the flange 166 of the metal core 160.

[0177] A plurality of protruding spacers 172 of elongated shape may be arranged on the stem portion 162, which facilitate positioning and orientation of the stem portion 172 in the stem mold 151 when the stem portion 162 is pushed through the proximal opening 153 into the stem mold 151. Here, the height of the spacers 172 is selected so that when the stem portion 162 is fully pushed into the stem mold 151, they abut against the inner wall of the interior space 152 of the stem mold 151. The limit stop for this purpose may be formed by the proximal wall 154 of the stem mold 151 and the distal surface 170 of the flange 166.

[0178] A plurality of protruding centering means 174, for example four protruding fins, can be provided on the head portion 164, which facilitates the positioning and orientation of the head portion 164 in the head mold 155, 205 when the head portion 164 is pushed through the corresponding distal opening 158, 208. The orientation of the fins is preferably selected so that they can slide along their linear surfaces into the hollow space 156, 206 of the head mold 155, 205. The head mold 155, 205 can have neck molds 178, 228 of different lengths, wherein the cylindrical inner space is a part of the hollow space 156, 206. The centering means 174 can slide on the cylindrical inner wall of the neck mold 178, 228. Here, the height of the centering means 174 is preferably selected so that when the head portion 164 is fully pushed into the head mold 155, 205, they abut against the cylindrical inner wall of the hollow space 156, 206 of the neck mold 178, 228. Limit stops for this purpose may be formed by the distal walls 159 , 209 of the head mould 155 , 205 and by the proximal surface 168 of the flange 166 .

[0179] The neck mold 178 may have a plurality of protruding rings 180 in the form of a peripheral thickening, along which the neck mold 178 can be cut and thus shortened. The neck mold 228 can be understood as the neck mold 178 that is shortened to the maximum extent. The rings 180 can be evenly spaced, in particular at even intervals of integer or half integer centimeters or inches. In this way, the length of the neck 194, 244 of the spacer 188, 238 to be produced can be adjusted, which is determined by the length of the corresponding neck mold 178, 228.

[0180] The flange 166 may have a plurality of protrusions 182 that may protrude in a radial or lateral direction from the metal core 166. The protrusions 182 may form the proximal surface 168 and / or the distal surface 170 of the flange 166, or may be part of the proximal surface 168 and / or the distal surface 170 of the flange 166. When the metal core 160 is pushed in, excess bone cement lumps may emerge from the stem mold 151, and in theory also from the head mold 155, 205 between the gaps between the protrusions 182.

[0181] A collar portion 184 may be formed on the stem mold 151 , the collar portion surrounding the flange 166 starting from the proximal wall 154 of the stem mold 151 .

[0182] According to the present invention, the shank mould 151 and the head mould 155,205 can be made by plastic material by injection moulding at low cost, or even can also be made by the plastic film of thermoforming, because even during the introduction of high viscosity bone cement paste mass, they do not have to bear any very large force.This is possible, because according to the present invention, the bone cement paste mass is introduced into the shank mould 151 and the head mould 155,205 as a casting mould, and the metal core 160 is not yet arranged therein, and therefore must flow around.It is possible to arrange the metal core 160 in the shank mould 151 and in one of the head mould 155,205 after introducing the bone cement paste mass, because the shank mould 151 and the head mould 155,205 are placed against the flange 166 of the metal core 160, and therefore can be arranged and oriented to cooperate with the metal core 160 and cooperate with each other.Therefore, the shank mould 151 and the head mould 155,205 do not need to be tightened or fastened together in an expensive, pressure-absorbing and stable manner.

[0183] Once the bone cement paste mass in the casting mold assembled by the stem mold 151 and one of the head molds 155, 205 has solidified on the metal core 160, the bone cement paste mass contained therein can be solidified. Subsequently, the resulting spacer 188, 238 can be demolded by pulling out the stem mold 151 and separating and removing the used head mold 155, 205. Fig.25The spacers 188, 238 are shown with the metal core 160 enclosed or mostly enclosed in the spacers 188, 238 to act as a reinforcement. The flange 166 or the protrusion 182 of the flange 166 is still evident on the surface of the spacers 188, 238 at the transition from the stem 192, 242 to the neck 294, 244 of the spacers 188, 238. The outer surface of the spacer 172 in the stem 192, 242 and the centering device 174 in the neck 194, 244 of the spacers 188, 238 are also evident.

[0184] exist Fig.24 C) to 24H) and can be Fig.25 C) to 25H) are made for the hip joint spacer 288 of the other variants, except for the smaller diameter of the spherical inner surface 257, and according to Figure 21-23 24A), 24B), 25A) and 25B). For simplicity, all of these exemplary embodiments use the same reference numerals, including embodiments of different shapes.

[0185] The device has a stem mold 251 and a head mold 255 and a metal core 260. The stem mold 251 and the head mold tool 255 are preferably a one-piece structure. The stem mold 251 and the head mold tool 255 can form a two-part casting mold for shaping a bone cement paste mass (not shown) introduced therein.

[0186] The stem mold 251 may have an interior space 252 in which a mass of bone cement may be formed to form the stem 292 of the spacer 288. The interior space 252 may be accessible via a proximal opening, such that a mass of bone cement may be introduced into the interior space 252 through the proximal opening of the stem mold 251, and the metal core 260 may be partially pushed into the interior space 252 of the stem mold 251 through the proximal opening. Around the proximal opening, the stem mold 251 may have a proximal wall that defines and closes the proximal opening.

[0187] The head mold 255 may have a hollow space 256 in which a mass of bone cement may be formed to form a head 290 of the spacer 288. On the proximal side of the hollow space 256, the hollow space 256 may have a spherical inner surface 257 of different diameters, which is used to form the actual articulation surface of the spacer 288. The spherical inner surface 257 of the hollow space 256 thus forms the hip articulation surface of the spacer 288, which is used to slide in the hip socket. The hollow space 256 is accessible via the distal opening, so that a mass of bone cement can be introduced into the hollow space 256 through the distal opening of the head mold 255, and the metal core 260 can be partially pushed into the hollow space 256 of the head mold 255 through the distal opening. Around the distal opening, the head mold 255 may have a distal wall that defines and closes the distal opening.

[0188] The metal core 160 can be made of a biocompatible metal, such as stainless steel or titanium. The metal core 160 is used to strengthen the spacer 288 and thus mechanically stabilize the spacer. The metal core 260 has a shaft portion 262, a head portion 264 and a flange 266, which is arranged between the shaft portion 262 and the head portion 264. The metal core 260 is preferably one-piece. The shaft portion 262 and the head portion 264 can be connected together by the flange 266. The flange 266 can extend in a radial direction from the axis of the head portion 264 and the shaft portion 262. The protruding flange 266 has a proximal surface and an opposite distal surface.

[0189] A plurality of protruding spacers 272 of elongated shape may be arranged on the stem portion 262, which facilitate positioning and orientation of the stem portion 262 in the stem mold 251 when the stem portion 262 is pushed through the proximal opening into the stem mold 251. Here, the height of the spacers 272 is selected so that when the stem portion 262 is fully pushed into the stem mold 251, these spacers abut against the inner wall of the inner space 252 of the stem mold 251.

[0190] A plurality of protruding centering devices 274, for example four protruding fins, may be provided on the head portion 264, which facilitate the positioning and orientation of the head portion 264 in the head mold 255 when the head portion 264 is pushed through the distal opening into the head mold 255. The orientation of the fins is preferably selected so that they can slide along their linear surfaces into the hollow space 256 of the head mold 255. The head mold 255 may have a neck mold 278 having a cylindrical inner space as part of the hollow space 256. The centering devices 274 can slide on the inner wall of the neck mold 278. Here preferably, the height of the centering devices 274 is selected so that when the head portion 264 is fully pushed into the head mold 255, they abut against the inner wall of the hollow space 256 of the neck mold 278 of the head mold 255.

[0191] According to the present invention, shaft mold 251 and head mold 255 can be produced by plastic material by injection molding at low cost, or even can also be produced by thermoforming plastic film, because even during introducing high viscosity bone cement paste, they do not have to bear any very large power.This is possible, because according to the present invention, bone cement paste mass is introduced in shaft mold 251 and head mold 255 as casting mold, and metal core 260 is not yet arranged therein, therefore must flow around.It is possible that metal core 260 is arranged in shaft mold 251 and head mold tool 255 after introducing bone cement paste mass, because shaft mold 251 and head mold tool 255 are placed against the flange 266 of metal core 260, and can be arranged and oriented accordingly to cooperate with metal core 260 and cooperate with each other.Therefore, shaft mold 251 and head mold tool 255 do not need to be tightened or fastened together in expensive, pressure absorbing and stable mode.

[0192] Once the bone cement paste mass is cured in the casting mold assembled by the stem mold 251 and the head mold 255 on the metal core 260, the bone cement paste mass contained therein is cured. Subsequently, the resulting spacer 288 can be demolded by pulling out the stem mold 251 and separating and disassembling the head mold 255. Fig.25 As shown, the spacer 288 is left with the metal core 260 enclosed or mostly enclosed in the spacer 288 as a reinforcement. The flange 266 at the transition from the stem 292 to the neck 294 of the spacer 288 is still clearly visible on the surface of the spacer 288. The outer surface of the spacer 272 in the stem 292 and the outer surface of the centering device 274 in the neck 294 of the spacer 288 are also clearly visible.

[0193] The features of the invention disclosed in the foregoing description and in the claims, the drawings and the exemplary embodiments may be essential both individually and in any combination for the realization of the invention in its various embodiments.

[0194] Reference numerals list

[0195] 1, 51, 151, 251 Rod mold

[0196] 2, 52, 152, 252 Internal space

[0197] 3, 53, 153 Proximal opening of the rod mold

[0198] 4, 54, 154 Near side wall of the rod mold

[0199] 5, 55, 105, 155, 205, 255 head mold

[0200] 6, 56, 106, 156, 206, 256 Hollow Space

[0201] 7, 57, 107, 157, 207, 257 Inner surface of a spherical shape

[0202] 8, 58, 108, 158 Distal opening of head mold

[0203] 9, 59, 109, 159 Far side wall of head mold

[0204] 10, 60, 160, 260 metal core

[0205] 12, 62, 162, 262 Rod part

[0206] 14, 64, 164, 264 Head part

[0207] 16, 66, 166, 266 flange

[0208] Proximal surface of flange of face 18, 68, 168

[0209] 20, 70, 170 Distal surface of flange

[0210] 22, 72, 172, 272 Isolators

[0211] 24, 74, 174, 274 Centering device

[0212] 26, 76 cone

[0213] 28, 78, 128, 178, 228, 278 Neck mold

[0214] 30, 80, 130, 180 rings

[0215] 32, 182 protrusions

[0216] 34, 84, 154 Collar

[0217] 36, 86 bone cement paste

[0218] 38, 88, 188, 238, 288 Spacers

[0219] 40, 90, 190, 240, 290 Spacer Head

[0220] 42, 92, 192, 242, 292 Spacer rod

[0221] 44, 94, 194, 244, 294 Spacer neck

[0222] 132 Bone Cement Applicator

[0223] 134 Barrel

[0224] 136 Barrel head

[0225] 138 Vacuum port

[0226] 140 Delivery pipe

[0227] 142 Turnbuckle nut.

Claims

1. A device for making a spacer by solidifying a bone cement paste dough, wherein: The spacer is provided in the medical field for temporary replacement of a joint or a part of a joint including an articulating surface of a joint head, the device having: A stem mold for forming a stem of the spacer from a bone cement paste dough, wherein the stem mold has an interior space in its interior, wherein the interior space is accessible via a proximal opening on a proximal side of the stem mold, and wherein the stem mold has a proximal wall circumferentially delimiting the proximal opening of the stem mold, A head mold for forming a head and a neck of a spacer from a mass of bone cement, wherein the head mold has a hollow space in its interior, wherein the hollow space has a spherical inner surface for forming a sliding surface of the head of the spacer, the hollow space being accessible via a distal opening on a distal side of the head mold, wherein the head mold has a distal wall circumferentially delimiting the distal opening of the head mold, A metal core, wherein the metal core has a shaft portion, a head portion and a flange, wherein the flange protrudes from the metal core, wherein the flange is arranged between the shaft portion and the head portion, and wherein the flange has a proximal surface and a distal surface, wherein the stem mold and the stem portion of the metal core are shaped so that when the proximal wall of the stem mold rests on the distal surface of the flange, the stem portion is arranged in the internal space of the stem mold, and Wherein, the head mold and the head portion of the metal core are shaped such that when the distal wall of the head mold rests on the proximal surface of the flange, the head portion is arranged in the hollow space of the head mold.

2. The device according to claim 1, characterized in that Such spacers are provided in the medical field for temporary replacement of hip joints or shoulder joints.

3. The device according to claim 1 or 2, characterized in that The metal core is composed of the shaft portion, the head portion and the flange, and / or the metal core is in one piece.

4. The device according to claim 1 or 2, characterized in that The shaft mold and / or the head mold are made of plastic material.

5. The device according to claim 1 or 2, characterized in that The shaft mold and / or the head mold consists of at least one plastic film or of an injection-molded plastic material.

6. The device according to claim 1 or 2, characterized in that When the proximal wall of the stem mold rests on the distal surface of the flange, the stem portion is spaced apart in the interior space of the stem mold from an inner wall of the stem mold that defines the interior space.

7. The device according to claim 6, characterized in that The proximal wall of the stem mold rests flush on the distal surface of the flange.

8. The device according to claim 1 or 2, characterized in that When the distal wall of the head mold rests on the proximal surface of the flange, the head portion is spaced apart in the hollow space of the head mold from the inner wall of the head mold that defines the hollow space.

9. The device according to claim 8, characterized in that The distal wall of the head mold rests flush on the proximal surface of the flange.

10. The device according to claim 1 or 2, characterized in that The head mold has a neck mold for forming the neck of the spacer from a mass of bone cement, the neck connecting the head and the stem, wherein the neck mold is tubular or hollow cylindrical, wherein the distal opening and the distal wall of the head mold are both parts of the neck mold, and the spherical inner surface of the hollow space is not part of the neck mold.

11. The device according to claim 10, characterized in that The head mold and the head portion of the metal core are shaped such that when the distal wall rests on the proximal surface of the flange, the head portion protrudes beyond the neck mold into the hollow space of the head mold.

12. The device according to claim 10, characterized in that The length of the neck mold can be adjusted by shortening the neck mold.

13. The device according to claim 12, characterized in that Predetermined cutting or tearing points are arranged on the neck mold and / or graduations are arranged on the outside of the neck mold.

14. The device according to claim 1 or 2, characterized in that The proximal surface of the flange limits displacement of the metal core in the head mold.

15. The device according to claim 1 or 2, characterized in that The distal surface of the flange limits displacement of the metal core in the stem mold.

16. The device according to claim 1 or 2, characterized in that A centering device is arranged on the head portion of the metal core, wherein the centering device protrudes from the surface of the head portion, wherein when the stem portion of the metal core is pushed into the hollow space of the head mold, the centering device keeps the inner wall of the head mold away from the head portion.

17. The device according to claim 16, characterized in that The head mold has a neck mold for forming a neck of the spacer from a bone cement paste ball, and when the stem portion of the metal core is pushed into the hollow space of the head mold, the neck mold of the head mold is spaced apart from the head portion.

18. The device according to claim 16, characterized in that The centering device is a centering fin, along which the head portion of the metal core can be axially displaced in the head mold.

19. The device according to claim 17, characterized in that The centering device is a centering fin, and the head portion of the metal core can be displaced in the neck mold.

20. The device according to claim 1 or 2, characterized in that An insulator is arranged on the rod portion of the metal core, wherein the insulator extends from the surface of the rod portion, and wherein when the rod portion of the metal core is pushed into the internal space of the rod mold, the insulator separates the inner wall of the rod mold from the rod portion of the metal core.

21. The device according to claim 1 or 2, characterized in that The outer circumference of the flange is larger than at least one of the proximal opening of the stem mold and the distal opening of the head mold.

22. The device according to claim 1 or 2, characterized in that At least one vent is arranged in at least one of the stem mold and the head mold, wherein the at least one vent connects at least one of the internal space of the stem mold and the hollow space of the head mold to the surrounding environment of the device in a gas-permeable manner.

23. The device according to claim 22, characterized in that The at least one vent is permeable to gas and impermeable to the bone cement mass.

24. The device according to claim 23, characterized in that The at least one vent is impermeable to the polymethylmethacrylate bone cement mass.

25. The device according to claim 1 or 2, characterized in that The apparatus includes cement powder packaged in at least one bacteria-proof cement container and monomer liquid packaged in at least one bacteria-proof and liquid-tight monomer liquid container.

26. The device according to claim 25, characterized in that The device has at least one bone cement cartridge for mixing cement powder with a monomer liquid and for delivering the mixed bone cement dough from the bone cement cartridge.

27. The device according to claim 26, characterized in that The device has a bone cement cartridge for mixing the polymethyl methacrylate bone cement starting components and for delivering the mixed polymethyl methacrylate bone cement dough therefrom.

28. The device according to claim 27, characterized in that The at least one bone cement cartridge has the at least one cement container and accommodates the at least one monomer liquid container, wherein the at least one cement container and the at least one monomer liquid container are arranged in areas separate from one another.

29. A kit for making different spacers by solidifying a bone cement paste dough, wherein: The spacer is provided in the medical field for temporary replacement of a joint or a part of a joint including an articular head articulation surface, and the kit has at least one device according to any of the preceding claims, wherein the kit has at least two head molds and / or at least two stem molds, the at least two head molds having spherical inner surfaces of different diameters, and the at least two stem molds having hollow spaces of different lengths in the distal direction or hollow spaces of different inner diameters.

30. The kit of claim 29, wherein: Such spacers are provided in the medical field for temporary replacement of hip joints or shoulder joints.

31. A kit according to claim 29 or 30, characterized in that The kit has at least two metal cores having head portions and / or shaft portions of different lengths.

32. A method for making a spacer for temporary replacement of a joint or a portion of a joint including an articulating surface of a joint head, wherein: The method is performed using a device according to any one of claims 1 to 28 or using a kit according to any one of claims 29 to 31, the method comprising the following steps: A) introducing the bone cement paste mass into the inner space of the stem mold, and introducing the bone cement paste mass into the hollow space of the head mold; B) pushing the head portion of the metal core into the hollow space of the head mold filled with the bone cement paste mass, thereby displacing the bone cement paste mass contained therein, until the distal wall of the head mold abuts against the proximal surface of the flange of the metal core, and pushing the stem portion of the metal core into the inner space of the stem mold filled with the bone cement paste mass, thereby displacing the bone cement paste mass contained therein, until the proximal wall of the stem mold abuts against the distal surface of the flange of the metal core; C) solidifying the bone cement paste in the head mold and the stem mold; as well as D) Removing the resulting shaped and cured spacer from the head and stem moulds.

33. The method according to claim 32, characterized in that This method is used to create spacers for temporary hip or shoulder replacements.

34. The method according to claim 32 or 33, characterized in that Prior to step A), the neck mold of the head mold is shortened according to the desired length of the neck of the spacer to be manufactured, a head mold with a spherical inner surface with a matching inner diameter is selected to match the desired shape of the head of the spacer to be manufactured, a stem mold with an internal space matching the desired shape of the stem of the spacer to be manufactured is selected, and / or a metal core with a size matching the desired shape of the stem of the spacer to be manufactured is selected.

35. The method according to claim 32 or 33, characterized in that Prior to step A), a homogeneous bone cement paste is prepared by mixing monomer liquid and cement powder.

36. The method according to claim 35, characterized in that In step A), the mixed bone cement dough is pressed into the inner space of the shaft mold and into the hollow space of the head mold using a bone cement cartridge.

37. The method according to claim 36, characterized in that When the mixed bone cement dough is pressed into the inner space of the stem mold and into the hollow space of the head mold by using a bone cement cartridge, air is discharged from the inner space of the stem mold and from the hollow space of the head mold.

38. The method according to claim 32 or 33, characterized in that In step B), the head portion of the metal core is centered in the head mold by means of a centering device.

39. The method according to claim 38, characterized in that The centering means are centering fins which protrude from the surface of the head portion and rest against the inner wall of the hollow space of the head mold when the head portion is pushed into the hollow space of the head mold.

40. The method according to claim 32 or 33, characterized in that In step B), the stem portion of the metal core is centered in the stem mold by means of a spacer which protrudes from the surface of the stem portion and rests against the inner wall of the inner space of the stem mold when the stem portion is pushed into the inner space of the stem mold.

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