Device for heating a component for the production of bone cement and method

Abstract

The invention relates to a method for producing bone cement and a device for heating a component for the production of bone cement. In a method for producing bone cement, two components (1, 2) are brought into contact with one another and mixed in order to produce bone cement. At least one component (2) of the two components (1, 2) or the produced bone cement is heated. A device (10) for heating a component (2) for the production of bone cement comprises a heating chamber (12) for receiving the component (2) and a heat source (20) for heating the component (2) located in the heating chamber (12). This enables accelerated curing and thus time savings when using bone cement.

Description

[0001] Heraeus Medical GmbH

[0002] H70360 / 2024PF00086 HME-BD

[0003] Device for heating a component for the production of bone cement and process

[0004] Description

[0005] The invention relates to a method for producing bone cement and a device for heating a component for producing bone cement.

[0006] Bone cement is typically produced by mixing a powder with a liquid. For example, polymethyl methacrylate (PMMA) bone cements are known to consist of a liquid monomer component and a powder component. When the powder component is mixed with the monomer component, a plastically deformable paste, the actual bone cement (also called bone cement paste), is formed, for example, through the swelling of polymers from the powder component in the methyl methacrylate. As the polymerization of the methyl methacrylate progresses, the viscosity of the bone cement increases until it hardens.

[0007] Bone cement is used, for example, to fix joint endoprostheses in the bony implant bed. For instance, primary or revision joint endoprostheses can be cemented, spacers or spacer components can be fabricated, such as for the interim phase of two-stage septic revisions of joint endoprostheses, or fractured vertebral bodies can be filled with bone cement. The features mentioned above can be combined with any aspects of the invention.

[0008] Known bone cements, especially high-viscosity ones, have a working time of approximately 3.5 minutes at room temperature under laboratory conditions, and then harden exothermically within a further 3 minutes or so. The working behavior of bone cement, particularly polymethyl methacrylate bone cement, is highly temperature-dependent. Under surgical conditions, hardening can take considerably longer.

[0009] Operating time is expensive, costing approximately €50 to €100 per minute. Saving operating time is therefore essential, also for cost reasons. Consequently, there is a need to shorten the hardening time of bone cement to reduce unnecessary waiting times. One approach is to modify the cement composition to achieve faster hardening. An example of this is the "PALACOS fast R+G" cement from Heraeus Medical GmbH. However, using such a cement requires experience and a skilled, rapid application by the medical practitioner.

[0010] The object of the invention is to enable accelerated hardening of bone cement in a particularly simple way.

[0011] The problem is solved by the method for producing bone cement according to claim 1 and the device for heating a component for producing bone cement according to the dependent claim. Advantageous embodiments are specified in the dependent claims.

[0012] To solve the problem, a method for producing bone cement is used in which two components are brought into contact and mixed to produce bone cement. At least one of the two components, or the produced bone cement, is heated.

[0013] Heating either one or both components, or heating the bone cement itself, results in the cement having a higher temperature during or after application, and consequently hardening more quickly. This makes it possible to accelerate the hardening of commercially available bone cements, such as polymethyl methacrylate bone cements, without altering their chemical composition, thus saving valuable surgical time. This can be used, for example, during the implantation of joint endoprostheses. Heating provides an acceleration impulse that can be applied externally. The clinician can then decide on a case-by-case basis whether the relatively slow-setting cement should be used in the usual way or whether accelerated hardening should be applied if necessary.

[0014] The two components are, in particular, a powder and a liquid. In one embodiment, at least the liquid is heated. This is more effective than heating the powder due to the liquid's superior thermal conductivity and heat transfer. The components are, in particular, designed to cause the bone cement to harden, especially through polymerization. Preferably, the components are mixed and, if necessary, brought into contact in a mixing container. The mixing container can be part of a mixing device. Typically, the bone cement is then dispensed from the mixing container for application at the site of application. Heating, in particular, takes place before the application of the bone cement. Both heating one or both components before mixing and heating the bone cement after mixing leads to accelerated hardening.

[0015] Heating a component can take place in a heating chamber and / or before adding it to the mixing container. Heating a component has the fundamental advantage that no additional step is required during the reaction time. This allows the bone cement to be processed as usual after production, without any additional time pressure.

[0016] In one embodiment, a container holding a component is located in a heating chamber during the heating process. A heating chamber is a cavity in which heating can take place. In this embodiment, the heating chamber is designed to accommodate the container with the component. The heating chamber can be part of a heating device. A heat source can be provided, particularly adjacent to the heating chamber, to heat a substance and / or an object located within the heating chamber. The container can be open or closed.

[0017] In particular, the container with the component is placed in the heating chamber before heating. After heating, the component can be removed directly from the container in the heating chamber. Removing the container from the heating chamber is not necessary. However, it is also possible to remove the container from the heating chamber if desired.

[0018] During surgery, for example immediately before the implantation of cemented joint endoprostheses, operating room personnel can heat a component such as monomer fluid to a temperature of at least 40 °C within a few seconds to a few minutes. This heating process accelerates the hardening of the polymethyl methacrylate bone cement paste by at least two minutes, thus saving operating time. In one embodiment, the container is held in the heating chamber by a holding device. Specifically, after heating, the holding device and container are removed from the heating chamber and / or mechanically coupled to a mixing device. This can be done to open the container.

[0019] In this process, the container, which is in particular an ampoule, is opened in a defined manner. The container is preferably located in an opening device that is connected, or can be connected, to the mixing device in such a way that the component can be transferred from the container to the mixing device. In particular, the opening device is mechanically connected to the mixing device. Specifically, a fluid channel for transporting the component is provided between the opening device and the mixing device. In this way, the transfer of the container from the heating chamber to the mixing device can be carried out particularly easily and precisely.

[0020] The holding device is coupled to the mixing device. For example, the holding device is inserted into a section of the mixing device, such as the opening mechanism.

[0021] The mixing device can be designed as a cartridge. The mixing device can include an interior space for mixing. The other component for producing bone cement, in particular the powder component, can be stored in this interior space. The mixing device can further include a mixing element located within the interior space, which is connected, for example, to a handle for manual mixing. The opening device can be formed by the holding device and / or the mixing device.

[0022] The holding device holds the container. Two or more containers with a single component can be held by the holding device. These can then be heated, removed, and / or opened simultaneously. The holding device can position the container so that at least part of its wall is exposed. This allows for particularly efficient heat transfer into the container while it is held by the device. The holding device may include a gripping area for manual handling.

[0023] The holding device can hold the container inside the opening device. The holding device can be configured to move together with the container relative to a shearing element for shearing off the head of an ampoule, so that the ampoule can be opened; the holding device can be hollow cylindrical.

[0024] The holding device can be part of a prepacked mixing system containing all the materials and equipment required for producing and dispensing bone cement. This facilitates handling of the container. The container can be stored in the holding device. The holding device with the container can be stored in the opening device. This corresponds to the usual arrangement in prepacked mixing systems. According to the invention, the holding device with the container can now be transferred to the heating device. This makes it possible to heat even a component of a prepacked mixing system in a simple manner. Alternatively, the holding device with the container can be stored in the heating chamber. The method can include inserting the holding device with the container held therein into the heating chamber.

[0025] Another aspect of the invention is a device for heating a component for the production of bone cement. The device comprises a heating chamber for holding the component and a heat source for heating the component located in the heating chamber. All advantages, features, and embodiments of the method described above can apply analogously to the device and vice versa.

[0026] The device allows for easy heating of the component. This component, used for the production of bone cement, is, for example, a liquid. As described, this directly leads to accelerated hardening. The device can, of course, also be configured to hold and heat the produced bone cement in the heating chamber.

[0027] The heating chamber is a cavity in which the component can be placed. The heating chamber can be largely or substantially closed. Typically, there is an external access point to the heating chamber through which the component can be introduced. This access point can be substantially or completely sealed. The heating chamber can be sealed or made sealed to such an extent that the component can be introduced in liquid or powder form. However, it is preferred that a typically closed container with the component is placed in the heating chamber. In this case, a completely sealed design is not essential.

[0028] The heat source is typically in thermal contact with the heating chamber. In the simplest case, the heat source is directly or indirectly adjacent to the heating chamber, allowing heat from the heat source to be transferred to the component located in the heating chamber via a short path. This heat transfer can occur, for example, through the wall of the container in which the component is located.

[0029] In particular, the device comprises a housing in which the heating chamber is arranged or formed. The device can be designed for single use. In this way, high hygiene requirements can be met while maintaining a simple design.

[0030] The device can include the component, in particular the container with the component. The container can be, for example, a bag, e.g., made of plastic or a plastic composite material, which may be coated with metal, or an ampoule, e.g., made of glass or plastic. Glass ampoules are particularly preferred, as they allow the liquid to be stored without loss for several years at room temperature and are also inexpensive to manufacture.

[0031] In one embodiment, the heat source includes a heat storage device that can release heat after activation. The heat storage device is, in particular, a thermochemical heat storage device.

[0032] A thermal energy storage system is a device that contains stored energy and can release it as heat when activated. This design allows for particularly simple triggering of the heat release, without batteries or accumulators, and without combustion. No fuel is required. It is possible to activate the heat release within seconds. Furthermore, by appropriately selecting the size and type of thermal energy storage system, or the quantity of the material(s) it contains, especially in relation to the quantity of the substance to be heated, a suitable target temperature and / or heating duration can be set. For example, it may be desirable for the heat release to occur within just a few minutes and then be reliably terminated.In particular, the heat storage unit is configured to heat a monomer liquid to a temperature of at least 40°C, preferably at least 50°C, and most preferably at least 60°C. This allows for a particularly effective reduction in the curing time. Specifically, the heating is carried out to a maximum of 90°C, preferably at most 85°C, and most preferably at most 80°C or 75°C. Excessively high temperatures can lead to significant evaporation or vaporization of the monomer, even to the point of boiling, and are therefore undesirable. For example, the typical monomer for PMMA bone cement boils at 101°C.

[0033] Thermochemical heat storage systems are systems that can release heat through a selectively activated exothermic reaction and / or a sorption reaction. Specifically, a thermochemical heat storage system contains a suitable heat storage medium that releases heat upon activation. Furthermore, a thermochemical heat storage system includes a space containing the heat storage medium.

[0034] The heat storage medium is, in particular, a solid and / or reacts exothermically with added water. "React" here does not necessarily mean a chemical reaction. For example, adsorption is also referred to as a reaction within the meaning of the invention. The heat storage medium is, in particular, an inorganic compound or a mixture of inorganic compounds. The heat storage medium can be water-soluble, partially soluble in water, or water-insoluble. In particular, the heat storage medium is selected such that no gas is released during the heat release reaction.

[0035] In addition to thermochemical heat storage systems, latent heat storage systems can also be used. However, these are not stable during transport, as vibrations can cause unwanted activation. This is not the case with thermochemical heat storage systems, which are stable during transport when stored in a sealed environment that prevents water ingress.

[0036] In one embodiment, the thermochemical heat storage device is designed to be activated by the addition of water. Pure water is not necessarily required for activation; an aqueous solution, such as a saline solution, can typically be used. Water or aqueous solutions are readily available in every operating room, thus providing a simple and universally applicable activation method. Furthermore, this embodiment eliminates the possibility of unintentional heat release during storage or transport of the device.

[0037] The device therefore comprises, in addition to the heating chamber, a further chamber. In particular, the device includes an opening through which water can be added to the chamber. In particular, the opening can be reversibly closed with a lid. In particular, the device includes a seal to enable a tight seal of the opening with the lid. In this way, added water cannot escape even if the device is moved or rotated.

[0038] In one embodiment, the thermochemical heat storage device comprises zeolite, silica gel, and / or anhydrous calcium chloride. Preferably, the material (the heat storage medium) is anhydrous, highly hygroscopic, and preferably possesses a large internal surface area. The aforementioned materials are non-flammable, non-explosive, non-self-igniting, ecologically and toxicologically safe, cost-effective, commercially readily available, and exhibit no loss of heat release even during prolonged storage. A silicate can be used. Zeolite is particularly preferred because it is readily available and does not produce acidic or alkaline solutions. Furthermore, heat release begins immediately upon the addition of water, enabling very rapid heating. Even after reacting with water, zeolites and silica gels are completely harmless, have a stable pH value, and can be disposed of without difficulty.

[0039] Alternatively or additionally, the thermochemical heat storage system can comprise a mixture of iron powder, sodium chlorate, and copper sulfate, and / or iron powder, sodium perchlorate, and copper sulfate. These mixtures are stable in dry storage. Heat is released only upon contact of the mixtures with water. The iron powder is oxidized to iron oxide by the sodium chlorate or sodium perchlorate, releasing heat in the process. The maximum temperature is determined by the ratio of iron powder to chlorate or perchlorate. For heating to temperatures below 100 °C, mixtures of iron powder with chlorate and perchlorate can be used, in which the chlorate or perchlorate is present in a substoichiometric amount in the mixture. In particular, the weight ratio of the heat storage medium to the water to be added must be at least 1.0 and / or at most 1.2.

[0040] In one embodiment, the thermochemical heat storage device comprises a heat storage medium in the form of particles. The particles have, in particular, a diameter of at least 0.1 mm and / or at most 4 mm.

[0041] The diameter is preferably at least 0.2 mm, particularly preferably 0.5 mm or

[0042] 1 mm. Particles that are too fine impede water penetration, resulting in uneven and / or delayed heating. The diameter is preferably at most 4 mm, particularly preferably at most 3 mm, and especially at most...

[0043] 2 mm. Particles that are too large reduce the contact area and thus delay heating. The particles can be in the form of granules, spheres, and / or rods.

[0044] In one embodiment, the thermochemical heat storage unit also contains a superabsorbent, particularly in the form of particles. This binds the supplied water and prevents it from sloshing or leaking out.

[0045] In one embodiment, the device further includes a temperature indicator for the optical display of a defined temperature inside the device. This allows for easy verification of whether heat release and temperature regulation of the monomer liquid have begun, or whether the temperature is within the desired range, for example, above 60°C. The temperature indicator can comprise a thermochromic substance and / or, for example, thermochromic liquid crystals. Upon reaching a defined temperature, the temperature indicator changes color. In particular, the temperature indicator is mounted on the top of the device or is visible from the top.

[0046] In one embodiment, at least one circumferential outer surface of the device is thermally insulated. The device can have a round and / or rectangular cross-section and / or be elongated. The circumferential outer surface refers to the side that bounds the device in the circumferential direction. In the case of a round cross-section, this can be a single lateral surface, and in the case of a rectangular cross-section, it can be composed of several surfaces, e.g., four. The device also has, in particular, a bottom surface, e.g., for placing the device on a base, and / or a top surface, for example, with access to the heating chamber and / or an opening to the chamber. In particular, the bottom surface is also thermally insulated. The thermal insulation can consist of a thermal insulation material, for example, a foam, such as a plastic foam.Alternatively or additionally, thermal insulation can be achieved through a double-walled construction of the outer wall, with an air space between two walls which may have negative pressure.

[0047] The thermal insulation reduces heat loss, thus ensuring faster curing. Furthermore, handling the device when hot becomes more comfortable and safer, as the risk of burns is eliminated.

[0048] In one embodiment, a wall separating the thermochemical heat storage unit from the heating chamber has one or more through-openings. These through-openings are designed to allow liquid, such as water, from the thermochemical heat storage chamber into the heating chamber. The container holding the component can then come into direct contact with the heated liquid. This further improves and accelerates heat transfer. In particular, at least 6, 10, or 15 through-openings are present.

[0049] In particular, a sealing element, e.g., in the form of an O-ring, is provided in the area of ​​the opening for inserting the container to seal the heating chamber against the inserted container, which is in particular an ampoule. This prevents liquid from escaping from the interior of the heating chamber and from contaminating the component during dispensing.

[0050] In one embodiment, an outer wall in the area of ​​the thermochemical heat storage unit is at least partially transparent or translucent. This is implemented in such a way that the fill level of any added liquid can be visually monitored through the transparent or translucent outer wall. This allows the user to easily see when sufficient liquid, such as water, has been added.

[0051] In particular, the thermochemical heat storage unit also contains a dye. This facilitates visual monitoring of the fill level. Specifically, the unit contains a water-soluble, non-toxic dye. Preferably, a green and / or blue dye is present. A food coloring is particularly preferred. For example, one or more of the following dyes can be used: methylene blue (CAS 61-73-4), indigo carmine (CAS 860-22-0), Green S (CAS 3087-16-9), patent blue V (CAS 20262-76-4), and water-soluble chlorophyllin (CAS 11006-34-1).

[0052] In one embodiment, the device has a cover, e.g., a flap, for closing the access point for inserting the container. The cover can be thermally insulated to further prevent heat loss. The cover can close the access point reversibly.

[0053] In one embodiment, the thermochemical heat storage device has a vent to allow displaced air to escape when water is added. Specifically, the vent is closed with a filter element, such as a sieve, mesh, or porous disc, to prevent the escape of the heat storage medium. A cover may be provided to reversibly close the vent.

[0054] In one embodiment, the thermochemical heat storage unit has two compartments. A first compartment is used for adding water. A second compartment contains a heat storage medium. The first and second compartments are connected only along the lower boundary of the compartment.

[0055] In particular, the first area contains no heat storage medium and / or is filled with air. The first and second areas are largely separated from each other and connected only at their lower boundary. The lower boundary is the boundary of the space opposite the top, where the water inlet is located. The lower boundary extends longitudinally along the space or device by a maximum of 20% of the total height of the space. Therefore, the connection does not necessarily have to be located directly at the lower boundary.

[0056] The water must therefore first flow completely through the first section to reach the second. This moistens the heat storage medium from below. Any resulting steam then enters the space containing the heat storage medium. This prevents steam from escaping from the opening during filling.

[0057] The first section can be small compared to the second. The first section can be, for example, a tubular inlet element located within the second section. This inlet element can have a solid wall that is only perforated or open at its lower boundary, or may be entirely absent. Any ventilation opening is located, in particular, in the second section.

[0058] In one embodiment, the device includes a holding device for securing the container in the heating chamber. The holding device is designed for mechanical coupling with a mixing device. The mixing device serves to mix two components for the production of bone cement and / or is a separate component.

[0059] An independent aspect of the invention is a system comprising a device according to the invention and a mixing device for mixing two components for the purpose of producing bone cement.

[0060] In a further embodiment of the device, the housing is manufactured at least substantially by plastic injection molding. "Substantially" means that at least essential parts of the housing are manufactured by plastic injection molding. These parts may then be joined, possibly with other manufactured parts. The housing forms the heating chamber and, in particular, an outer casing of the device and / or a space for holding the heat storage medium. This allows for simple and cost-effective manufacturing.

[0061] Alternatively or additionally, the device consists at least predominantly of thermoplastic material. Alternatively or additionally, the device is designed in such a way that it can be easily disposed of with normal hospital waste.

[0062] A method according to the invention, in particular using a device according to the invention, may comprise one or more of the following steps in any combination:

[0063] - If necessary, open a cover to gain access to the heating chamber,

[0064] Bringing the container into the heating room, in particular via the access point,

[0065] - If necessary, close the cover,

[0066] - Opening the lid,

[0067] Add water to activate the heating process, - Close the lid if necessary.

[0068] Especially after heating: if necessary, open the cover.

[0069] - Opening the container to remove the component, removing the component.

[0070] Another aspect of the invention is the use of a component, in particular heated to over 40°C, for the production of bone cement.

[0071] Examples

[0072] To test the workability of polymethyl methacrylate bone cement, a ball is typically formed from cement paste by hand, and its deformability is manually checked over time. The hardening of the ball is determined acoustically by tapping it. Complete hardening can be recognized by a clear, ringing sound when tapped. With a cement powder quantity of 40 g, the ball being tested has a diameter of approximately 4.5 cm. Due to its spherical shape, the surface area to volume ratio of the cement ball is small. While polymerization starts relatively uniformly throughout the entire volume of the ball, it accelerates significantly in the interior due to heat buildup from the released heat of polymerization. This heat can only be dissipated slowly to the outside.This increases the temperature inside the sphere, which in turn significantly accelerates the polymerization rate. Furthermore, a certain amount of heat energy is introduced into the bone cement during the sphere's formation by hand. Under these conditions, a bone cement like Heraeus Palacos requires approximately 6 to 6.5 minutes to harden.

[0073] In surgical practice, it is evident that hardening occurs significantly later than under laboratory conditions. Heraeus Palacos requires approximately 11 to 13 minutes, while bone cements from other manufacturers sometimes take even longer. This is partly due to the fact that the polymethyl methacrylate bone cement is present as a thin layer, only a few millimeters thick, for example, on the surface of a prosthesis. This means that the ratio of cement surface area to cement volume is considerably higher than with cement beads, and the heat generated is thus dissipated more effectively. Furthermore, joint endoprostheses are typically made of chromium-cobalt steel and therefore exhibit good thermal conductivity and high heat capacity. As a result, the cement paste is very effectively cooled by the adjacent joint endoprosthesis, and hardening begins later or proceeds more slowly than with a cement paste bead under laboratory conditions.

[0074] Since the processing time averages 3 to 3.5 minutes, a long waiting period of 8 to 10 minutes is required before the bone cement hardens. According to the invention, this waiting time can be reduced by 3 to 3.5 minutes.

[0075] Example 1 - Laboratory conditions

[0076] First, the hardening of PMMA bone cement was determined as a function of the temperature of the monomer liquid used. For this purpose, 40.8 g of PMMA bone cement powder PALACOS® R+G, which was at room temperature, was mixed in a mixing bowl with 20 ml of monomer liquid, which had previously been heated to room temperature, 40 °C, 50 °C, 60 °C, and 70 °C, using a spatula. The processing and hardening behavior of the mixed PMMA bone cement paste was determined using a hand-formed cement ball approximately 4.5 cm in diameter, in accordance with ISO 5833.

[0077] The results are shown in Table 1 below. The table depicts the start and end of the processing phase, as well as the curing time, in seconds or minutes from the end of mixing. The start of the processing phase is characterized by the absence of tackiness. The end of the processing phase is characterized by a transition from plastically deformable to elastic behavior. This can be determined by folding a plate produced from the sphere. As soon as the plate begins to stand upright, the processing phase is over. The end of curing is tested acoustically as described above.

[0078] Table 1

[0079] The results of the experiments show that the time until curing decreases significantly with increasing temperature of the monomer liquid. If the monomer liquid is at 70°C instead of room temperature, an acceleration of more than 2 minutes is already possible under laboratory conditions.

[0080] Example 2 - more practical conditions

[0081] In surgical practice, medical practitioners often check the hardening of PMMA bone cement after implantation by pressing a spatula or other solid object into the exposed area of ​​the PMMA cement between the bony implant site and the prosthetic component. Once the spatula can no longer be pressed into the cement and a light-colored sound is produced when the spatula is tapped on the cement, the cement is considered hardened.

[0082] Based on this test method, an experimental setup was developed to simulate the hardening of PMMA bone cement for the cementation of knee endoprostheses, in order to determine the influence of the monomer fluid temperature on the hardening time under more realistic conditions. When cementing knee endoprostheses, the cement layer thickness is typically in the range of approximately 3 mm to 4 mm. The tibial and femoral components each have a mass, depending on their type and size, in the range of approximately 130 g to 230 g. Both components are usually made of chromium-cobalt steel and are brought to room temperature before implantation. This means that the components act as heat sinks, absorbing the heat energy released during the hardening of the PMMA bone cement. This cools the PMMA bone cement. The temperature of the bony implant bed is in the range of 36 °C to 37 °C.The following experimental setup was developed to simulate these conditions:

[0083] A POM plastic sheet measuring 10.0 cm x 10.0 cm x 1.0 cm and weighing 153.2 g was placed on the laboratory table as an insulating layer. A stainless steel plate with a mass of 293.5 g and dimensions of 7.8 cm x 4.8 cm x 1.0 cm, representing a component of a knee endoprosthesis, was placed on top of this. The stainless steel plate was at room temperature. Its mass was greater than that of the endoprosthesis components typically used, as described above. A steel frame with outer dimensions of 7.7 cm x 5.4 cm and a height of 3.45 mm, and inner dimensions of 6.5 cm x 4.2 cm and a height of 3.45 mm, was then placed on top of the stainless steel plate.

[0084] 20 ml of PALACOS monomer liquid (Lot 1336) were tempered to room temperature, 40 °C, 50 °C, 60 °C, and 70 °C. 20 ml of the tempered monomer liquid was added to a PALAMIXO mixing system, followed by the addition of 40.8 g of PALACOS® R+G cement powder (Lot 6976). After closing the mixing system, the mixture was quickly mixed manually. The resulting cement paste, for example, with a temperature between 35 °C and 40 °C, was then dispensed from the Palamix mixing system into the frame using a duckbill-shaped nozzle and a manually operated dispensing device. Then a plastic film was laid on top and an HVPC plastic sheet tempered to 37°C with a mass of 144.1 g and dimensions of 10.0 cm x 10.0 cm x 1.0 cm was pressed onto the film until the cement dough had a flat surface and was flush with the top edge of the metal frame.The cement paste in the frame thus had a layer thickness of 3.45 mm. The plastic plate, heated to 37 °C, was left on the cement paste for 4.0 minutes to simulate the heat input from the bony implant bed. Then, at 30-second intervals, the hardening of the bone cement paste was checked by pressing on it or tapping it with a metal spatula.

[0085] The results of this experiment are shown in Table 2 below.

[0086] Table 2. It is evident that curing takes longer under more realistic conditions. The results show that, despite cooling by the metal plate (modeling the prosthesis component) and simultaneous heat input from the plastic plate (modeling the bony implant bed, heated to 37 °C), a significant reduction in curing time is achieved by using heated monomer liquid. A reduction of 3 minutes can be achieved.

[0087] Example 3 - Determining the heating 1

[0088] In the following, a device according to the invention was manufactured by 3D printing using selective laser sintering (SLS) from the plastic PA12. The device was filled with 90 g of dried zeolite A (spheres with a diameter of 1.6 mm). A glass ampoule containing 20 ml of monomer liquid was inserted into the device. The ampoule head was broken off, and a temperature sensor from the Testo 725-2 temperature measuring unit was inserted. Then, 90 ml of water was added to the device. Heat generation began immediately after the addition of the water. The temperature of the monomer liquid in the glass ampoule was measured every minute from the time the water was added. The results are given in Table 3.

[0089] Table 3

[0090] It is evident that a temperature above 60 °C is reached after just one minute and maintained for at least 10 minutes. From minute 3 to minute 6, a temperature of at least 70 °C was reached. The subsequent cooling process is slow.

[0091] Example 4 - Determining the heating 2

[0092] In a further experiment based on the one described above, 65 g of dried zeolite A were mixed with 65 ml of water in the apparatus. Heat generation began immediately after the addition of the water. The results are shown in Table 4.

[0093] Table 4

[0094] The temperatures are lower. A temperature above 50 °C is reached after 3 minutes and maintained for at least 8 minutes. In the scenario examined here, no cooling occurred in the first 10 minutes; the temperature remained constant from minute 5 onwards.

[0095] Exemplary embodiments of the invention are explained in more detail below, also with reference to figures. Features of the exemplary embodiments can be combined individually or in multiples with the claimed subject matter, unless otherwise specified. The claimed scope of protection is not limited to the exemplary embodiments.

[0096] They show:

[0097] Figure 1: a schematic representation of a device,

[0098] Figure 2: Steps of a process for the production of bone cement,

[0099] Figure 3: a perspective view of a device,

[0100] Figures 5 to 8: Sectional drawings of a device in use,

[0101] Figure 9: a sectional drawing of another device,

[0102] Figures 10 and 12: enlarged details,

[0103] Figure 11: a perspective view of a device, as well as

[0104] Figures 13 to 16: Drawings of a device in use.

[0105] Figure 1 shows a simple device 10 according to the invention for heating a component 2 for the production of bone cement. The device 10 comprises a heating chamber 12, which can be heated by means of a heat source 20. Typically, the heating chamber 12 and the heat source 20 are arranged in a main body of the device 10. A bottom surface 18 of the device is designed for placement on a base. In particular, the heating chamber 12 is accessible from above. There is an access point 14 to the heating chamber 12, especially on the top surface 19. A container 6 with the component 2 located therein can be inserted into the heating chamber through the access point 14.

[0106] Figure 2 shows the steps of a process. First, at least one component is heated to produce bone cement. Then, this component is brought into contact and mixed with at least one other component. In this way, bone cement is produced. Due to the prior heating, the hardening process is faster than with conventional methods.

[0107] Figures 3 and 4 show a further embodiment of a device 10 for heating a component 2 for the production of bone cement. The device 10 comprises a heating chamber 12 for receiving the component or a container with the component, which is accessible from above via an access point 14. The device 10 further comprises a chamber 26 for a heat storage medium as a heat source, in particular a thermochemical heat storage medium. The heat storage medium comprises a heat storage medium (not shown) which releases heat after activation by adding a liquid. For this purpose, the chamber 26 includes an opening 28 through which the liquid can be poured in.

[0108] The opening 28 is closed by a lid 27. The access 14 is closed by a cover 15. In the embodiment shown here, the lid 27 and the cover 15 are designed as a single unit and connected to each other by a common handle 38. In this way, they can be opened and closed together.

[0109] The wall 30, which separates the heating chamber 12 from the chamber 26 of the heat storage unit, has a large number of through-holes. This allows liquid from the heat storage unit to enter the heating chamber 12, to wet the container and accelerate the heating of the component.

[0110] The outer wall 17 is ribbed to improve grip when grasping manually and to reduce the contact area with the hand. This reduces the risk of burns. The device 10 includes a spout 39 for the controlled pouring of the heated component.

[0111] Figures 5 to 8 show steps in the use of the device 10, in particular the device 10 from Figures 3 and 4. Figure 5 shows a state in which a heat storage medium 21, namely a thermochemical heat storage medium 22, is present as the heat source 20. A heat storage medium 23, for example zeolite particles 24, is located in the chamber 26. A container 6, namely an ampoule 8, has been inserted into the heating chamber 12. The ampoule 8 contains a component 2 for the production of bone cement, in particular a liquid monomer component.

[0112] In this embodiment, the unit consisting of lid 27 and cover 15 has longer guide elements in the area of ​​lid 27 than in the area of ​​cover 15. This allows the unit to be partially pulled upwards in an axial direction, so that cover 15 is released, but lid 27 remains at least partially fixed. The unit was then rotated 180° about a vertically oriented axis and pushed downwards again to reach the position shown. This allowed the ampoule 8 to be inserted while the chamber 26 remained closed. Premature activation of the heat source 20 and / or the release of heat storage medium 23 were thus prevented.

[0113] Figure 6 shows a state in which the unit consisting of lid 27 and cover 15 has been completely removed and a liquid, such as water, is poured into the chamber 26 through the opening, for example using a syringe 48. This activates the heat source and heats the component. The lid 27 can then be replaced to prevent leakage of water and / or heat storage medium.

[0114] After a few minutes, the heating process is complete. The head 9 of the cartridge can be broken off, as shown in Figure 7. Subsequently, as shown in Figure 8, the entire device 10 can be tilted to allow the heated component 10 to flow out. This is made possible, among other things, by the sealing element 13, which seals the access point opposite the ampoule 8, as shown in Figure 7, and clamps the ampoule 8 in place.

[0115] Figures 9 to 13 show a further developed device 10 based on the device shown in Figures 3 to 8. The following discussion focuses solely on the differences. Various components have been modified, and according to the invention, these modifications can be implemented independently of one another. Firstly, as can be seen in Figure 9, the circumferential outer surface 16, which in the case of the circular cylindrical base shown here is the lateral surface of the device, is thermally insulated. This is achieved, for example, by providing a double wall. Air, a vacuum, and / or an insulating material such as a plastic foam is located in the space between the individual layers of the double wall. In the embodiment shown here, the underside 18 is also thermally insulated in this way. The space between the outer surface 16 and the underside 18 is continuous, similar to a thermos flask.

[0116] Furthermore, the chamber 26 of the thermochemical heat storage unit is divided into two sections 41 and 42, which are separated by a wall 43 and connected only at the lower boundary 46 of the chamber 26. The water must therefore first flow through the first section 41 before it can enter the second section 42 in the lower part of the chamber 26. The first section 41 is empty or filled with air, while the second section 42 contains the heat storage medium (not shown here). Filling the chamber with water is thus quick and easy, and the heat storage medium only comes into contact with the water in the second section 42. This prevents any escaping of water vapor through the opening 28.

[0117] The connection 44 located below, between the first area 41 and the second area 42, is shown enlarged in Figure 10. The first area 41 is shown here as a tubular shape and extends downwards, in particular in a straight line, from the opening 26. It can be seen that a perforated inlet element 45, in the form of a basket, is arranged in the first area 41. The inlet element 45 prevents the heat storage medium from entering the first area 41. The wall 43 is open or absent at the bottom in the area of ​​the connection 44. In the embodiment shown here, the connection abuts directly against the lower boundary 46 of the chamber 26.

[0118] Furthermore, the cover 15 is designed separately from the lid 27. However, an additional vent opening 34 is provided, connecting the chamber 26 to the environment. The lid 27 is shown as an example unit with a cover 35 for the vent opening 34. The unit has a common handle. As can be seen in the enlarged view in Figure 12, the vent opening 34 is closed with a filter element 36, which allows gases to pass through and retains solids and / or liquids.

[0119] Furthermore, a funnel 49 is provided, which serves to break off the head of the ampoule 8 and / or to dispense the component from the ampoule 8 in a controlled manner. The funnel 49 can be placed over the access point 14 and / or attached in the area of ​​the access point 14.

[0120] Figures 14 to 16 show a further developed device 10, which is based on the device of Figures 9 to 13. Only the differences are discussed below. Modifications have been made to various components, which, according to the invention, can be implemented independently of one another or not.

[0121] The device 10 is designed to accommodate two or more containers 6, particularly in the form of ampoules 8, side by side. For this purpose, the device 10 can have an elongated cross-section. Furthermore, a holding device 50 is provided, which holds the two or more containers 6. The holding device 50 can be inserted into the heating chamber 12 along with the containers. The device 10 can include the holding device 50.

[0122] The holding device 50 with the containers 6 can be mechanically coupled to a mixing device 52, as shown in Figures 15 and 16. In particular, the mixing device 52 comprises a mixing container 53 with an interior 54 for mixing bone cement. The mixing container 53 is designed as a cartridge. A mixing element 55, for example a mixing plate, is arranged in the interior 54 and can be manually moved back and forth along the longitudinal axis of the mixing container 53 within the interior 54 to produce bone cement by mixing the components. The second component, in the embodiment shown here a powder component or a PMMA powder, can be stored in the interior 54.

[0123] The holding device 50 is mechanically coupled to an opening device 56, which is mechanically connected to and / or part of the mixing device 52. The opening device 56 forms a cavity into which the holding device 50, with the containers, can be inserted along its longitudinal axis. The inserted state is shown in Figure 16. The ampoules 8 are oriented with their heads 9 pointing downwards. Near the head 9 is a shearing element 62, for example, wedge-shaped. The holding device 50 can be moved along its longitudinal axis within the cavity 56 of the opening device 56. A locking clip 60 prevents the holding device 50 from being inserted further.

[0124] The locking clip 60 can be pulled off or removed, out of the plane of the image as shown in Figure 16. This releases the insertion of the holding device 50 into the opening device 56. By manually applying axial pressure to the holding device 50 or the ampoule 8, the head 9 of the ampoule 8 is pressed obliquely against the shearing element 61 and thus broken off.

[0125] A fluid channel 58 is arranged between the cavity and the mixing vessel 53, through which the heated monomer liquid from the ampoule 8 can flow into the interior 54 without loss, particularly by gravity. The fluid channel 58 may have a funnel-shaped section. Preferably, a filter 64 is located in the fluid channel 58 to retain any glass fragments that may form. The fluid channel 58 may have an inlet tube at its lower end for introducing the liquid into the interior 54. The inlet tube may be designed so that it can be withdrawn after the liquid has been introduced. A closure, for example a slide valve, may be provided on the mixing vessel 53, e.g., in the head of the cartridge, to subsequently close the mixing vessel 53.

[0126] When the monomer liquid in the interior is 54, the bone cement can be produced by manual mixing as described and / or under the influence of a vacuum. The bone cement is then dispensed, for example by squeezing, e.g., using a squeegee, and / or accelerated by a vacuum.

[0127] Reference symbol list

[0128] Component 1

[0129] Component 2

[0130] Container 6

[0131] Ampoule 8

[0132] Head 9

[0133] Device 10

[0134] Heating room 12

[0135] Sealing element 13

[0136] Entrance 14

[0137] Cover 15

[0138] Outside 16

[0139] Exterior wall 17

[0140] Bottom 18 Top 19

[0141] Heat source 20

[0142] Heat storage 21

[0143] Thermochemical heat storage 22 Heat storage medium 23

[0144] Particle 24

[0145] Room 26

[0146] Lid 27

[0147] Opening 28 Water 29

[0148] Wall 30

[0149] Passage opening 32

[0150] Vent opening 34

[0151] Lid 35 Filter element 36

[0152] Handle 38

[0153] Spout 39

[0154] First area 41

[0155] Second area 42, wall 43

[0156] Connection 44

[0157] Inlet element 45

[0158] Lower limit 46

[0159] Syringe 48 Funnel 49

[0160] Holding device 50

[0161] Mixing device 52

[0162] Mixing container 53

[0163] Interior 54 Mixing element 55

[0164] Opening device 56

[0165] Fluid channel 58

[0166] Safety clip 60

[0167] Shearing element 62 Filter 64

[0168] Warm up 70

[0169] Contact and mixing 72

[0170] Bone cement 74

Claims

Heraeus Medical GmbH H70360 / 2024PF00086 HME-BD Claims 1. A method for producing bone cement in which two components (1, 2) are brought into contact and mixed to produce bone cement, characterized in that at least one component (2) of the two components (1, 2) or the produced bone cement is heated.

2. Method according to the preceding claim, characterized in that a container (6) containing a component (2) is located in a heating chamber (12) during heating.

3. Method according to the preceding claim, characterized in that the container (6) is held by a holding device (50) in the heating chamber (12), wherein the holding device (50) with the container (6) is removed from the heating chamber (12) after heating and mechanically coupled to a mixing device (52).

4. Device (10) for heating a component (2) for the production of bone cement, comprising a heating chamber (12) for receiving the component (2) and a heat source (20) for heating the component (2) located in the heating chamber (12).

5. Device (10) according to the preceding claim, wherein the heat source (20) comprises a heat storage device (21) which can release heat after activation, in particular a thermochemical heat storage device (22).

6. Device (10) according to the preceding claim, characterized in that the thermochemical heat storage device (22) is designed such that it can be activated by adding water (29), and / or that the thermochemical heat storage device (22) comprises zeolite, silica gel and / or anhydrous calcium chloride.

7. Device (10) according to the preceding claim, wherein the thermochemical heat storage medium (22) comprises a heat storage medium (23) which is in the form of particles (24) with a diameter of at least 0.1 mm and / or at most 4 mm.

8. Device (10) according to one of the four preceding claims, further comprising a temperature indicator for optically displaying a defined temperature inside the device (10).

9. Device (10) according to one of the five preceding claims, wherein at least one circumferential outer surface (16) of the device (10) is thermally insulated.

10. Device (10) according to one of the six preceding claims, wherein a wall separating the thermochemical heat storage (22) from the heating chamber (12) has one or more through-openings (32).

11. Device (10) according to one of the seven preceding claims, wherein an outer wall (17) of the device (10) in the area of ​​the thermochemical heat storage (22) is at least partially transparent or translucent.

12. Device (10) according to one of the six preceding claims, wherein the thermochemical heat storage device (22) has a vent opening (36) to allow displaced air to escape when water (29) is added.

13. Device (10) according to one of the seven preceding claims, wherein a space (26) of the thermochemical heat storage unit (22) has two areas (41, 42), wherein a first area (41) serves for adding the water (29) and a second area (42) contains a heat storage medium, wherein the first area (41) and the second area (42) are connected to each other only in the area of ​​a lower boundary (46) of the space (26).

14. Device (10) according to one of the ten preceding claims, wherein the device (10) has a holding device (50) for holding the container (6) in the heating chamber (12), wherein the holding device (50) is configured for mechanical coupling with a mixing device (52).

15. Device (10) according to one of the eleven preceding claims, wherein a housing of the device (10) is manufactured at least substantially by plastic injection molding.

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