Abstract:
A device and methods mix polymethylmethacrylate bone cement and/or store the starting components of the bone cement. The device comprising: a cartridge with an internal space for mixing the bone cement that is closed on one side by means of a mobile dispensing plunger; a monomer container for a monomer liquid and/or a connector for attachment of a monomer container for a monomer liquid such that the monomer container can be opened appropriately in the device such that the monomer liquid flows from the monomer container into the device; a connecting conduit through which the monomer liquid can be guided into the internal space of the cartridge. A first hollow cylinder is connected to the connecting conduit and a second hollow cylinder is connected, via a vacuum conduit, to the internal space of the cartridge, whereby a pumping plunger is shiftable axially in the first hollow cylinder and is arranged in the first hollow cylinder and a vacuum plunger that is shiftable axially in the second hollow cylinder is arranged in the second hollow cylinder, whereby the pumping plunger and the vacuum plunger may be moved simultaneously.

Description:
[0001]    This application claims foreign priority benefit under 35 U.S.C. §119 of German Application No. DE 10 2015 108 783.9, filed Jun. 3, 2015. 
         [0002]    The invention relates to a mixing system for the mixing of polymethylmethacrylate bone cement (PMMA bone cement) from two starting components, in particular for the mixing of a medical bone cement, and for storage of the starting components. 
         [0003]    The invention further relates to a method for the mixing of polymethylmethacrylate bone cement. 
         [0004]    Accordingly, the object of the invention is a device for storage and mixing of polymethylmethacrylate bone cement and method for the mixing of polymethylmethacrylate bone cement. 
         [0005]    Polymethylmethacrylate (PMMA) bone cements are based on the pioneering work of Sir Charnley (Charnley, J.: Anchorage of the femoral head prosthesis of the shaft of the femur. J. Bone Joint Surg. 42 (1960) 28-30). PMMA bone cements consist of a liquid monomer component and a powder component. The monomer component generally contains the monomer, methylmethacrylate, and an activator (N,N-dimethyl-p-toluidine) dissolved therein. The powder component, which is also referred to as bone cement powder, comprises one or more polymers, a radiopaquer, and the initiator dibenzoylperoxide. The polymers of the powder component are produced on the basis of methylmethacrylate and comonomers, such as styrene, methylacrylate or similar monomers by means of polymerisation, preferably by suspension polymerisation. During the mixing of powder component and monomer component, swelling of the polymers of the powder component in the methylmethacrylate generates a dough that can be shaped plastically and is the actual bone cement. During the mixing of powder component and monomer component, the activator, N,N-dimethyl-p-toluidine, reacts with dibenzoylperoxide while forming radicals. The radicals thus formed trigger the radical polymerisation of the methylmethacrylate. Upon advancing polymerisation of the methylmethacrylate, the viscosity of the cement dough increases until the cement dough solidifies. 
         [0006]    Methylmethacrylate is the monomer used most commonly in polymethylmethacrylate bone cements. Redox initiator systems usually consist of peroxides, accelerators and, if applicable, suitable reducing agents. Radicals are formed only if all ingredients of the redox initiator systems act in concert. For this reason, the ingredients of the redox initiator system in the separate starting components are arranged appropriately such that these cannot trigger a radical polymerisation. The starting components are stable during storage provided their composition is adequate. Only when the two starting components are mixed to produce a cement dough, the ingredients of the redox initiator system, previously stored separately in the two pastes, liquids or powders react with each other forming radicals which trigger the radical polymerisation of the at least one monomer. The radical polymerisation then leads to the formation of polymers while consuming the monomer, whereby the cement dough is cured. 
         [0007]    PMMA bone cements can be mixed by mixing the cement powder and the monomer liquid in suitable mixing beakers with the aid of spatulas. Said procedure is disadvantageous in that air inclusions might arise and/or be present in the cement dough thus formed, which may have a detrimental effect on the mechanical properties of the cured bone cement and might cause destabilisation of the bone cement later on. 
         [0008]    A large number of vacuum cementing systems has been proposed for preventing air inclusions in bone cement dough of which the following shall be specified here for exemplary purposes: U.S. Pat. No. 6,033,105 A, U.S. Pat. No. 5,624,184 A, U.S. Pat. No. 4,671,263 A, U.S. Pat. No. 4,973,168 A, U.S. Pat. No. 5,100,241 A, WO 99/67015 A1, EP 1 020 167 A2, U.S. Pat. No. 5,586,821 A, EP 1 016 452 A2, DE 36 40 279 A1, WO 94/26403 A1, EP 1 005 901 A2, U.S. Pat. No. 5,344,232 A. The vacuum cementing systems thus specified, need to have an external vacuum pump connected to them in order to generate the negative pressure. These are generally operated by compressed air utilising the Venturi principle. The compressed air required for operation of the vacuum pumps is supplied either by stationary compressed air facilities or by electrically-operated compressors. In addition, it is also feasible to use electrically-operated vacuum pumps to generate vacuum. 
         [0009]    Cementing systems, in which both the cement powder and the monomer liquid are already packed in separate compartments of the mixing systems and are mixed with each other in the cementing system only right before application of the cement, are a development of cementing technology. Said closed full-prepacked mixing systems were proposed through EP 0 692 229 A1, DE 10 2009 031 178 B3, U.S. Pat. No. 5,997,544 A, U.S. Pat. No. 6,709,149 B1, DE 698 12 726 T2, and U.S. Pat. No. 5,588,745 A. Said mixing systems also require an external vacuum source. A device for the mixing of bone cement, in which the vacuum can be generated by means of a manual pump and in which a monomer liquid is injected by means of a syringe that can be connected to it, is known from EP 1 259 200 B1. However, the system described therein is not a full-prepacked mixing system and, in addition, is associated with a disadvantage in that the vacuum pump and the syringe containing the monomer liquid need to be manually connected to the device in laborious manner. The various requisite handling steps make the device rather time-consuming to handle. 
         [0010]    Patent DE 10 2009 031 178 B3 discloses a generic mixing system having a two-part dispensing plunger for the closing of a cement cartridge. A combination of a gas-permeable sterilisation plunger and a gas-impermeable sealing plunger is used in this context. This principle of a closed vacuum mixing system is implemented in the closed cementing system, PALACOS® PRO, made and distributed by Heraeus Medical GmbH. 
         [0011]    WO 00/35506 A1 proposes a device, in which the polymethylmethacrylate bone cement powder is stored in a cartridge, whereby the cement powder takes up the entire volume of the cartridge and the volume of the intervening spaces between the particles of the cement powder is equal to the volume of the monomer liquid required for the production of bone cement dough using the cement powder stored in the cartridge. The design of said device is appropriate such that the action of a vacuum causes the monomer liquid to be supplied into the cartridge from above, whereby a vacuum is applied to a vacuum connector on the underside of the cartridge for this purpose. As a result, the monomer liquid is aspirated through the cement powder, whereby the air present in the intervening spaces of the cement particles is replaced by the monomer liquid. This involves no mechanical mixing of the cement dough thus formed by means of a stirrer. 
         [0012]    It is a disadvantage of the system that cement powders, which swell quickly due to the monomer liquid, cannot be mixed with said device, because the rapidly swelling cement powder particles form a gel-like barrier of approximately 1 to 2 cm after ingress of the monomer liquid into the cement powder and impede the migration of the monomer liquid through the entire cement powder. Moreover, employing the action of a vacuum, it cannot be excluded that the monomer liquid is suctioned off through the vacuum connector after it fully penetrates the cement powder. In this case, there a sufficient amount of monomer liquid for curing by means of radical polymerisation is no longer available and/or the mixing ratio and thus the consistency of the bone cement is changed inadvertently. Moreover, it is a problem that the air trapped between the cement powder particles is to be displaced by the monomer liquid proceeding from top to bottom, because the air, having a lower specific weight than the monomer liquid, tends to migrate upwards in the cement powder rather than downwards in the direction of the vacuum connector under the force of gravity. 
         [0013]    If vacuum mixing systems are used for cementing, external vacuum pumps need to be provided in most cases. Said vacuum pumps are expensive and need to be cleaned after use. Moreover, vacuum hoses for connecting the vacuum pumps to the vacuum mixing systems are required. Said vacuum hoses need to be enclosed with the vacuum mixing systems. Accordingly, prior to the mixing using a vacuum mixing system, the vacuum pump first needs to be set-up in the surgical theatre (OR) and must be connected to an energy source, such as compressed air or electrical power. Then, the vacuum pump is connected to the vacuum mixing system by means of a vacuum hose. Said installation steps take up costly OR time and are potentially error-prone. The vacuum pump and connecting conduits to the vacuum mixing system and to external energy sources and supply conduits take up space and are potential tripping hazards and stumbling blocks that can disturb the often hectic procedure during a surgery. 
         [0014]    An interesting concept has been proposed through EP 1 886 647 A1. Here, the cement powder is stored in an evacuated cartridge and the monomer liquid is situated in a separate container. The cartridge, which is kept at a negative pressure, being opened causes the monomer liquid to be aspirated into the cartridge without any ingress of air. A bone cement dough free of air inclusions is thus produced. Said concept requires the cartridge to remain closed in vacuum-tight manner during the storage before use such that no non-sterile air can enter into the cartridge. For this purpose, the cartridge must be hermetically sealed in a stable manner. Accordingly, one associated disadvantage is that the design is quite elaborate and that the content of the cartridge cannot be mixed by an externally-operated mixing system after aspiration of the monomer liquid since a feed-through for a mixing rod or for a mixing tube would not readily be permanently vacuum-tight. 
         [0015]    Accordingly, it is the object of the invention to overcome the disadvantages of the prior art. In particular, the disadvantages of the known vacuum mixing systems with external vacuum source and/or elaborate design and elaborate operation are to be overcome. It is one of the objects of the invention to develop a simple closed device, in which polymethylmethacrylate bone cement powder (cement powder) and monomer liquid can be stored in separate compartments and can be mixed with each other subsequently. It shall be possible for the medical user to combine and mix the polymethylmethacrylate bone cement powder (PMMA bone cement powder) and the monomer liquid inside the device, without the medical user being exposed to both cement components. Exposure of the medical user to the polymethylmethacrylate bone cement powder and to the monomer liquid shall be excluded as much as possible. The device to be developed is a full-prepacked mixing system. The nature of the device shall be appropriate such that the monomer liquid can be transferred into the polymethylmethacrylate bone cement powder without the use of external vacuum pumps driven by compressed air or compressors. It is also important that the device ensures the production of bone cement doughs functionally and reliably without the use of external energy sources, such as compressed air, vacuum or electrical current, even under the simplest external conditions. It shall be possible to use the device autonomously without any additional technical equipment. Moreover, the design shall be as simple and inexpensive as possible. It shall be possible to operate the device easily even under difficult conditions. 
         [0016]    Moreover, it is an object of the invention to provide a device, in which the volume of monomer liquid transferred into the cement powder can be controlled specifically such that the ratio of the volume of monomer liquid to the quantity of cement powder can be varied in order to control the consistency and thus the processing properties of the bone cement. Moreover, air bubbles shall be prevented from being present in the ready-mixed bone cement. 
         [0017]    Moreover, a method is to be provided that enables a monomer transfer and a mixing in full-prepacked mixing systems. In this context, it shall be possible to manufacture the mixing system (the device) to be developed mainly from inexpensive plastics. 
         [0018]    Moreover, a device that is inexpensive to manufacture and works reliably for the mixing of a medical cement and, if applicable, for storage of the starting components of the cement, and a method for the mixing of the bone cement is to be devised, in which a simple manual operation can be used to mix the starting components, if possible without having to use an external or additional energy source and without air inclusions arising in the mixing material. 
         [0019]    The main component of the polymethylmethacrylate bone cement, as mixing material, shall be a powder and the second component shall be present in the form of a liquid. Preferably, it shall be possible to store the two starting components of the bone cement separate from each other in the full-prepacked mixing system and to combine them safely through the use of the device. 
         [0020]    The objects of the invention are met by a device for the mixing of polymethylmethacrylate bone cement and for storage of the starting components of the bone cement, in particular of a monomer liquid and a cement powder, as starting components of the bone cement, the device comprising 
         [0000]    A) a cartridge with an internal space for mixing the bone cement that is closed on one side by means of a mobile dispensing plunger;
 
B) a monomer container for a monomer liquid and/or a connector for attachment of a monomer container for a monomer liquid such that the monomer container can be opened appropriately in the device such that the monomer liquid flows from the monomer container into the device;
 
C) a connecting conduit through which the monomer liquid can be guided into the internal space of the cartridge, whereby
 
D) a first hollow cylinder is connected to the connecting conduit and a second hollow cylinder is connected, via a vacuum conduit, to the internal space of the cartridge, whereby a pumping plunger that can be shifted axially in the first hollow cylinder is arranged in the first hollow cylinder and a vacuum plunger that can be shifted axially in the second hollow cylinder is arranged in the second hollow cylinder, whereby, according to the invention, the pumping plunger and the vacuum plunger can be moved simultaneously.
 
         [0021]    In particular, the pumping plunger and the vacuum plunger can be movable synchronous to each other. 
         [0022]    It is particularly preferable to design the first and the second hollow cylinder as a shared hollow cylinder, inside of which a combined pumping/vacuum plunger moves, whereby a first side, in particular the underside, of the pumping-vacuum plunger forms the pumping plunger and a second side, in particular the upper side, of the pumping-vacuum plunger forms the vacuum plunger. In this case, the upper part of the shared hollow cylinder shall be considered to be the second hollow cylinder and the lower part of the shared hollow cylinder shall be considered to be the first hollow cylinder in the scope of the present invention. 
         [0023]    In order for the monomer liquid to flow from the opened monomer container into the first hollow cylinder, the opened monomer container is connected to the first hollow cylinder, preferably is connected to the first hollow cylinder by means of a junction. 
         [0024]    For the monomer liquid to flow without any additional action of a force, the device must be set up properly such that gravity effects the desired direction of flow. Accordingly, the terms, top, and, bottom, and, above, and, below, and, highest, and, lowest, as used in the scope of the present invention shall be understood to always relate to the device being set-up properly. 
         [0025]    Preferably, the internal space of the cartridge has a cylindrical geometry. The cylindrical geometry is the simplest geometry that allows the internal space of the cartridge and the first and the second hollow cylinder to be implemented. A cylindrical internal space shall be understood geometrically to mean the shape of a general cylinder with any footprint, i.e. not just a cylinder with a circular footprint. Accordingly, the internal wall of the internal space can be a cylinder of any footprint and the jacket of the first and second hollow cylinder can be a cylinder of any footprint, i.e. including a non-circular or round footprint. However, a cylindrical geometry with a rotationally symmetrical footprint is preferred according to the invention. 
         [0026]    In order to attain a good pumping effect and prevent the monomer liquid from leaking from the pumping plunger and/or the first hollow cylinder, the pumping plunger closes, such as to be fluid-tight, against the internal walls of the first hollow cylinder. A circumferential seal that closes the pumping plunger with respect to the internal walls of the first hollow cylinder can be provided for this purpose. Likewise, a circumferential seal can be provided in order to seal the vacuum plunger with respect to the internal walls of the second hollow cylinder such that no or at least very little air is drawn from the other side of the vacuum plunger, when a negative pressure is generated with the vacuum plunger. 
         [0027]    It is preferred, according to the invention, to have the monomer container be connected to the connector for the monomer container or to have the monomer container be inserted in the connector for the monomer container. 
         [0028]    Preferably, the polymethylmethacrylate bone cement is mixed and/or can be produced from at least two components. Particularly preferably, one component is liquid (the monomer liquid) and the other component is powdered (the cement powder). 
         [0029]    According to the invention, the starting components for the mixing material, in particular for the PMMA bone cement, are already present in the cartridge and the monomer container. 
         [0030]    It is preferred, according to the invention, that the device is also well-suited for storage of the starting components, in particular when the containers, in particular the monomer container, are inserted into the device or the containers, in particular the monomer container, are a fixed part of the device. 
         [0031]    The device according to the invention can also be provided such that the pumping plunger and the vacuum plunger are connected to each other appropriately or are moved by means of a shared operating element such that, when the pumping plunger is being slid into the first hollow cylinder, the vacuum plunger in the second hollow cylinder moves away from the connection to the vacuum conduit, whereby the volume between the vacuum plunger and the connection to the vacuum conduit in the second hollow cylinder preferably enlarges such that the negative pressure arising in the second hollow cylinder causes a gas to flow from the internal space of the cartridge through the vacuum conduit into the second hollow cylinder. 
         [0032]    The enlargement of the volume between the vacuum plunger and the connection to the vacuum conduit in the second hollow cylinder is associated with the generation of a negative pressure that draws gas from the internal space of the cartridge through the vacuum conduit into the second hollow cylinder and/or such that gas is being pushed from the internal space of the cartridge through the vacuum conduit into the second hollow cylinder. 
         [0033]    As a result, a single motion causes the monomer liquid to be pushed from the hollow cylinder into the internal space of the cartridge and causes the air to be drawn from the internal space of the cartridge. 
         [0034]    Moreover, the invention can provide the first hollow cylinder to be connected to the monomer container and/or the connector for attachment of a monomer container in appropriate manner such that the monomer liquid flows from the opened monomer container or an opened attached monomer container into the first hollow cylinder and such that the connecting conduit connects the first hollow cylinder to the internal space of the cartridge in appropriate manner such that the pumping plunger can be used to push monomer liquid from the first hollow cylinder through the connecting conduit into the internal space of the cartridge by actuating the pumping plunger. 
         [0035]    This ensures that the device can be designed in simple and easy manner and without additional components or an electronic regulation or control. This allows the device to be used in places without energy supply. 
         [0036]    Moreover, the invention can provide the first hollow cylinder to be arranged between the monomer container or the connector for the monomer container and the internal wall of the cartridge. In this context, the invention can preferably provide the first hollow cylinder to be arranged in the connecting conduit between the monomer container or the connector for the monomer container and the internal wall of the cartridge. 
         [0037]    This allows to dispense with an additional conduit and there is no need for re-plugging the connecting conduit. This simplifies the application of the device even more. 
         [0038]    The first hollow cylinder being arranged between the monomer container for the monomer liquid or the connector for the monomer liquid and the cartridge does not mean that the hollow cylinder is geometrically arranged in between these, but is arranged between arranged between the monomer container for the monomer liquid or the connector for the monomer liquid and the cartridge with respect to the liquid connections, i.e. with respect to the flow direction of the monomer liquid flowing and/or being pumped from the opened monomer container in the direction of the cartridge. 
         [0039]    A refinement of the present invention proposes the pumping plunger and the first hollow cylinder to comprise a smaller cross-sectional area than the vacuum plunger and the second hollow cylinder, preferably the vacuum plunger and the second hollow cylinder to comprise a cross-sectional area at least twice as large as the pumping plunger and the first hollow cylinder. 
         [0040]    As a result, a larger amount of gas can be evacuated from the internal space of the cartridge by the vacuum plunger. Concurrently, the force expended to actuate the pumping plunger is not too large such the device, in particular the pumping plunger and vacuum plunger connected to each other, can easily be operated by hand. 
         [0041]    The invention can just as well provide the pumping plunger and the vacuum plunger to be connected to each other, preferably to be affixed to each other, particularly preferably to be designed as a single part. 
         [0042]    This attains a particularly stable and simple design. 
         [0043]    In this context, the invention can just as well provide the side of the vacuum plunger facing the vacuum conduit to be arranged on the rear side of the pumping plunger and, correspondingly, the side of the pumping plunger facing the connecting conduit to be arranged on the rear side of the vacuum plunger. 
         [0044]    Accordingly, according to the invention, the pumping plunger and the vacuum plunger can be implemented in the form of a shared pumping-vacuum plunger, which simplifies the design of the device. Moreover, this implements a two-side plunger principle that is particularly easy to apply, in which both sides of the combined pumping-vacuum plunger and/or both front faces of the combined pumping-vacuum plunger are used to perform the work based on a joint motion, namely both the pumping of the monomer liquid into the internal space of the cartridge and the generation of a negative pressure for evacuation of the internal space of the cartridge. 
         [0045]    The invention further proposes to have the vacuum conduit connected to the internal space of the cartridge by means of the dispensing plunger, whereby the dispensing plunger preferably has a filter or a screen arranged in it by means of which the vacuum conduit is connected to the internal space of the cartridge. 
         [0046]    Preferably, the dispensing plunger has a two-part design that includes a sterilisation plunger and a feed plunger, whereby the sterilisation plunger and the feed plunger can be connected to each other. 
         [0047]    As a result, the connector for the vacuum conduit can earlier be used for evacuation and for sterilization with a gas. Moreover, the connector is thus arranged opposite from a dispensing opening of the cartridge through which the monomer liquid is also pushed into the internal space of the cartridge, i.e. into which the connecting conduit merges into the internal space of the cartridge. As a result, the negative pressure can aspirate the monomer liquid into the cartridge and thus support the filling of the cartridge with the monomer liquid even more. 
         [0048]    A refinement of the present invention can provide the monomer container to be arranged or arrangeable in a flexible ampoule container, whereby it is preferable to provide at least one ventilation opening in the ampoule container. 
         [0049]    As a result, it is easy to open an ampoule as monomer container by bending the ampoule container and thus breaking the ampoule such as to be open. The ventilation opening helps the monomer liquid to flow out easily. Moreover, the at least one ventilation opening can be used for sterilisation of the device with ethylene oxide. 
         [0050]    According to a preferred refinement, the present invention can provide a mixing facility that can be operated from outside to be arranged in the cartridge, whereby the mixing facility preferably can be operated by means of a mixing rod that is guided through a feed-through in the dispensing plunger into the interior of the cartridge and is supported such as to be mobile. 
         [0051]    It is particularly preferable for the mixing rod to be supported such that it can be rotated in the feed-through and can be shifted in longitudinal direction. The content of the internal space of the cartridge can be mixed conveniently with the mixing rod of the mixing facility. Referring to the use of low viscosity bone cements, the use of a mixing rod and a mixing facility is dispensable, because the monomer liquid displaces the air of the pore spaces between the cement powder particles and wets the cement powder particles before the cement powder swells. 
         [0052]    The invention can just as well provide the dispensing plunger to be impermeable for powders, whereby it is preferred to arrange a pore filter in the dispensing plunger that is permeable for gas and impermeable for powder. 
         [0053]    It is preferable to design the pore filter as pore disk. The impermeability for powder prevents the cement powder from leaking from the interior of the cartridge. If the dispensing plunger is gas-permeable, the internal space can be evacuated through the dispensing plunger and can be sterilised with a gas, such as, for example, ethylene oxide. The vacuum conduit preferably merges via the dispensing plunger, in particular via the pore disk, into the internal space of the cartridge. 
         [0054]    Preferably, the invention can just as well provide the internal space of the cartridge to contain the cement powder. 
         [0055]    The invention can just as well provide the monomer container to contain the monomer liquid. As a result, the device is a ready-made full-prepacked mixing system that does not need to be filled with the cement powder prior to use. Prior to use, the cement powder is stored in the cartridge separate from the monomer liquid. 
         [0056]    The invention also proposes a filter that is impermeable for the cement powder and permeable for the monomer liquid to be arranged between the connecting conduit and the internal space of the cartridge. 
         [0057]    As a result, the cement powder can be prevented from ingress into the connecting conduit and from polymerising in this place when the monomer liquid is supplied and thus can be prevented from inadvertently clogging and/or blocking, like a glue, the connecting conduit. 
         [0058]    Preferred embodiments can provide the device to comprise a base, in which at least a part of the connecting conduit is arranged, whereby the cartridge is connected to the base in detachable manner, in particular is connected to the base in detachable manner by means of a screw thread, whereby the filter, if any, that is impermeable for the cement powder and permeable for the monomer liquid is arranged in the base of the device, particularly preferably is arranged in the connection to the cartridge of the base. 
         [0059]    As a result, the device is easy to set up and operate. 
         [0060]    In this context, the invention can provide the first hollow cylinder, the second hollow cylinder, and the monomer container or the first hollow cylinder, the second hollow cylinder, and the connector for attaching the monomer container to be connected to the base, preferably to be connected to the base in non-detachable manner. 
         [0061]    As a result, a particularly simple and inexpensive design of the device is attained. 
         [0062]    The present invention also proposes the monomer container for the monomer liquid or the connector for attaching the monomer container to merge into the first hollow cylinder on a jacket surface of the first hollow cylinder, preferably to merge into the first hollow cylinder right below the pumping plunger. 
         [0063]    As a result, it can be ensured that the monomer liquid can completely flow into the hollow cylinder and can fill the hollow cylinder. Moreover, air can exit from the hollow cylinder particularly easily at this site. 
         [0064]    Moreover, the invention can provide the device to comprise opening means for opening the monomer container by means of which the monomer container can be opened inside the device, whereby it is preferred to have a screen or a filter arranged in the connection to the first hollow cylinder by means of which fragments or shreds of the opened monomer container can be retained. 
         [0065]    Preferably, the invention can provide the monomer container to be a breakable glass ampoule in this context. 
         [0066]    The opening means being a part of the device allows the device to also be used for long-term storage of the monomer. A suitable opening means is known, for example, from the DE 10 2010 026 496 B4 patent. 
         [0067]    Moreover, the invention can provide the monomer container to be arranged above the connection to the first hollow cylinder. 
         [0068]    By this means, the monomer liquid can flow from the monomer container into the first hollow cylinder due to the action of gravity after the monomer container is opened. Alternatively, the monomer container could just as well be squeezed out and the monomer could thus flow into the first hollow cylinder. 
         [0069]    Preferred devices can also be characterised in that the connecting conduit is connected to the first hollow cylinder on the lower side, preferably is connected to the first hollow cylinder on the lowest point of the first hollow cylinder, whereby it is particularly preferred to have the pumping plunger be arranged on the opposite side of the first hollow cylinder. 
         [0070]    As a result, the monomer liquid can be made to flow and/or can be pushed completely out of the first hollow cylinder by means of the pumping plunger. 
         [0071]    Moreover, the invention proposes the first hollow cylinder to comprise, on the side opposite from the pumping plunger, a conical, semi-spherical or otherwise downwards-tapering bottom, whereby the surface of the pumping plunger facing the bottom of the first hollow cylinder preferably is a negative mould of the bottom. 
         [0072]    As a result, the monomer liquid can be made to flow and/or can be pushed completely out of the first hollow cylinder by means of the pumping plunger. This means that all of the monomer liquid flows to the lowest point of the first hollow cylinder and that there are no “dead” regions, in which monomer liquid remains behind when the pumping plunger is actuated. Since the shape of the pumping plunger is adapted to the inner shape of the first hollow cylinder, all of the monomer liquid is pressed out of the first hollow cylinder through the pumping plunger when the pumping plunger is moved in the direction of the opening to the connecting conduit without any residual monomer liquid remaining in the first hollow cylinder. Moreover the shape of the front face of the pumping plunger being conical or spherical and/or fitting ensures that, when the pumping plunger moves downward and/or in the direction of the base, the air above the monomer liquid in the first hollow cylinder can escape through the opening in the jacket surface of the first hollow cylinder and no air bubbles remain above the monomer liquid during transfer of the monomer liquid into the internal space of the cartridge and/or into the cement powder. 
         [0073]    Preferred devices according to the invention can also be characterised in that the pumping plunger can be moved axially in the first hollow cylinder by hand, preferably can be pressed axially into the first hollow cylinder by hand and/or the vacuum plunger can be moved axially in the second hollow cylinder by hand. 
         [0074]    By this means, it is feasible to press the monomer liquid out of the first hollow cylinder by hand and to transfer it into the internal space of the cartridge and/or to generate the vacuum in the second hollow cylinder by hand in order to evacuate air from the cartridge. 
         [0075]    To simplify the operation and to increase the variability of devices according to the invention, the invention can just as well provide the first hollow cylinder to be transparent and to comprise markings indicating the filling level of a liquid in the first hollow cylinder. 
         [0076]    As a result, an amount of the monomer liquid determined by the markings can be filled into the first hollow cylinder and/or can be pressed from the first hollow cylinder into the internal space of the cartridge. This provides an opportunity to use the device to produce a bone cement dough of a consistency that is predetermined by the amount of the monomer liquid. Alternatively, the first hollow cylinder can just as well be non-transparent and markings can be provided on an operating element of the pumping plunger and/or vacuum plunger projecting from the housing of the device in order to be able to enable defined propulsion of the pumping plunger and thus to be able to press a defined volume of the monomer liquid from the first hollow cylinder. Accordingly, said designs allow the entire volume of the monomer liquid to be pressed from the first hollow cylinder into the cement powder in the internal space of the cartridge as well as to transfer just certain partial volumes of the monomer liquid from the first hollow cylinder into the cement powder. As a result, the ratio of monomer liquid and amount of powder can be adjusted, which allows the time at which the cement dough thus formed becomes non-tacky and the viscosity of the bone cement to be controlled specifically. 
         [0077]    The invention can just as well provide the first hollow cylinder and/or the second hollow cylinder to comprise an internal thread and the pumping plunger and/or the vacuum plunger to comprise a matching external thread such that the pumping plunger and/or the vacuum plunger can be screwed into the first hollow cylinder and/or the second hollow cylinder in order to press the monomer liquid out of the first hollow cylinder into the internal space of the cartridge and/or to draw air out of the internal space of the cartridge into the second hollow cylinder. 
         [0078]    This also allows a defined amount of the monomer liquid to be pressed out of the hollow cylinder into the internal space of the cartridge. This provides an opportunity to use the device to produce a bone cement dough of a consistency that is determined by the amount of the monomer liquid. Moreover, the negative pressure in the second hollow cylinder can be generated by a large force. Concurrently, having the thread present reduces the risk of the vacuum plunger inadvertently moving in the direction of the connector to the vacuum conduit due to the negative pressure. If the vacuum plunger has a larger cross-section than the pumping plunger, which is preferred according to the invention, it may suffice to have only the vacuum plunger comprise an external thread that can be screwed into an internal thread of the second hollow cylinder. This applies especially when the pumping plunger and the vacuum plunger are designed as a shared pumping-vacuum plunger. 
         [0079]    Moreover, the invention can provide the device to comprise at least one tensioned compression spring and at least one locking mechanism, whereby the compression spring, the vacuum plunger and/or the pumping plunger is or are locked by means of the at least one locking mechanism in detachable manner, whereby the at least one compression spring, with the locking mechanism detached, exerts a pressure on the pumping plunger and/or the vacuum plunger such that the pumping plunger is pressed into the first hollow cylinder and/or the vacuum plunger is pushed away from the connector to the vacuum conduit in the second hollow cylinder. 
         [0080]    Referring to the embodiment, in which the first and/or second hollow cylinder comprise an internal thread and the pumping plunger and/or the vacuum plunger comprise an external thread, at least one tensioned volute spring can be provided in analogous manner, which screws the pumping plunger into the first hollow cylinder and/or the vacuum plunger into the second hollow cylinder after detachment of at least one locking mechanism. 
         [0081]    These measures are advantageous in that they simplify the operation of the device. Moreover, possible operating errors can thus be prevented. 
         [0082]    Moreover, the invention can provide the dispensing plunger to be connected to the cartridge by means of a detachable snap-in device, whereby the snap-in device can be detached by hand, in particular through the action of an axial force, such that the dispensing plunger can be moved axially in the internal space of the cartridge. 
         [0083]    As a result, the dispensing plunger can be prevented from moving inadvertently such as may be caused by a vacuum or a negative pressure in the internal space of the cartridge. 
         [0084]    The invention also proposes the connecting conduit between the first hollow cylinder and the internal space of the cartridge to comprise a loop that faces upwards, whereby the topmost point of the loop is situated above a junction of the monomer container or of the connector for the monomer container into the first hollow cylinder. 
         [0085]    This can prevent the monomer liquid from already reaching the internal space of the cartridge via the connecting conduit while it is being filled into the first hollow cylinder. The effect of the connecting conduit having said U-shaped loop is that the monomer liquid in the first hollow cylinder remains in the connecting conduit up to the level of the apex before the pumping plunger is moved in the direction of the connecting conduit, which prevents premature ingress of the monomer liquid to the cement powder. In particular in the case of high viscosity cements, premature contact even of small volumes of monomer liquid with the cement powder can block, like a glue, the connecting conduit or a conduit means provided as a nozzle, as is described in U.S. Pat. No. 8,662,736 B2. The connecting conduit can be transparent or translucent to allow the user to visually check the monomer transfer. For this purpose, in particular, an inspection window, through which the loop with the highest apex can be seen, can be provided in the device. 
         [0086]    Moreover, the invention can provide the volume in the first hollow cylinder to be smaller than or equal to the volume of the monomer liquid in the monomer container. 
         [0087]    As a result, air is prevented from being pressed along into the cement powder when the pumping plunger is being actuated. 
         [0088]    Moreover, the invention can provide the internal space of the cartridge to be connected, on the lower side, to the connecting conduit in liquid-permeable manner. 
         [0089]    In the front face of the internal space, the connecting conduit can merge into a nozzle in accordance with U.S. Pat. No. 8,662,736 B4. Said nozzle prevents the entry of cement powder into the connecting means. 
         [0090]    The objects underlying the present invention are also met by a method for the mixing of bone cement, in particular with the device according to the invention, comprising the chronological steps of 
         [0000]    A) a monomer container being opened,
 
B) a monomer liquid flowing from the monomer container into a first hollow cylinder, whereby the first hollow cylinder is bounded on one side by a pumping plunger,
 
C) the pumping plunger being pushed into the first hollow cylinder and the monomer liquid thus being pressed out of the first hollow cylinder and through a connecting conduit into the internal space of a cartridge, whereby a cement powder is situated in the internal space of the cartridge,
 
D) the motion of the pumping plunger moving a vacuum plunger, which is connected to the pumping plunger or driven parallel to same, in a second hollow cylinder away from a connector of a vacuum conduit, whereby the gas pressure between the connector of the vacuum conduit and the vacuum plunger in the second hollow cylinder is reduced due to the motion of the vacuum plunger and gas is evacuated, through the vacuum conduit, from the internal space of the cartridge that is connected to the vacuum conduit, and
 
E) the monomer liquid and the cement powder being mixed in the internal space of the cartridge.
 
         [0091]    Preferably, the monomer liquid flows into the hollow cylinder due to the action of gravity. 
         [0092]    In this context, the invention can provide the monomer liquid and the cement powder to be mixed in the internal space of the cartridge only once the pumping plunger has been pushed in fully or up to a marking in the first hollow cylinder, whereby the marking is a measure of the [amount of] monomer liquid supplied into the internal space of the cartridge. 
         [0093]    As a result, it can be made sure by means of the desired admixture of monomer liquid that the bone cement dough thus generated has the desired consistency. 
         [0094]    Methods according to the invention can also be provided appropriately such that the air is aspirated from the internal space of the cartridge through the vacuum conduit on the side opposite from the junction of the connecting conduit, whereby it is preferred to have the connecting conduit merge into the internal space of the cartridge on the underside of the internal space and to have the vacuum conduit merge into the internal space of the cartridge on the upper side of the internal space. 
         [0095]    As a result, it can be made sure that the monomer liquid can be supplied into the internal space of the cartridge and the air can be evacuated from the internal space of the cartridge simultaneously. Moreover, this can prevent the monomer liquid from inadvertently ingressing into the vacuum conduit. 
         [0096]    Moreover, the invention proposes the monomer liquid and the cement powder to be mixed in the internal space by means of a mixing facility by operating the mixing facility by moving a mixing rod that extends into the internal space of the cartridge and can be rotated and can be shifted in longitudinal direction, whereby it is preferred to pull the mixing rod out of the internal space of the cartridge up to the limit stop after the mixing and it is particularly preferred to break off the mixing rod at a predetermined breakage site after pulling it out to the limit stop. 
         [0097]    As a result, the method can be implemented through manual operation. 
         [0098]    Moreover, the invention can provide the monomer container to be opened through operating a triggering and opening means, whereby it is preferred to have the monomer container be broken open by the opening means. 
         [0099]    As a result, the monomer container can be opened inside the device such that the entire device can be closed with respect to the outside. 
         [0100]    Moreover, the invention can provide the pumping plunger to be pushed into the first hollow cylinder by means of a tensioned elastic spring element and/or the vacuum plunger to be moved in the second hollow cylinder by means of a tensioned elastic spring element, whereby it is preferred to first detach at least one locking mechanism that engages or engage the pumping plunger, the vacuum plunger and/or the spring element for this purpose. 
         [0101]    This attains further automation of the method according to the invention and also prevents potential operating errors. 
         [0102]    The invention can just as well provide the cartridge containing the ready-mixed cement dough to be detached from the connecting conduit, vacuum conduit, first hollow cylinder, second hollow cylinder and monomer container, and the ready-mixed cement dough to be dispensed from the internal space of the cartridge through propulsion of a dispensing plunger, which is supported in the cartridge such as to be axially mobile and forms a boundary of the internal space of the cartridge on one side. 
         [0103]    The invention is based on finding, surprisingly, that a monomer liquid can be pressed into the internal space of a cartridge from below by means of a pumping plunger and that a negative pressure can be generated in the internal space of the cartridge by concurrently moving a vacuum plunger in a hollow cylinder such that no interfering air inclusions are formed in the bone cement. Concurrently, set device allows to largely dispense with external energy sources or internal energy accumulators since the pumping plunger and the vacuum plunger can be operated by hand. In particular, no vacuum sources and connectors and components that are vacuum-tight in the long term need to be used, which simplifies the use in less-developed places as well as local use or use in field hospitals significantly. Moreover full-prepacked mixing systems according to the invention are less susceptible to possible disturbances and are therefore highly likely to be ready for use, since no vacuum leaks can occur. 
         [0104]    For example, a device according to the invention and/or a method according to the invention can be provided appropriately such that, after a monomer container is opened, the monomer liquid flows into a hollow cylinder due to the action of gravity, [and] is then pressed from same into the internal space of the cartridge containing cement powder through manual actuation of the pumping plunger. This means that the transfer of monomer liquid proceeds through the action of a pressure rather than a vacuum, which is in contrast to the previous commercial mixing systems. A manually actuated monomer transfer effected by the action of a pressure can be implemented inexpensively using simple plastic parts that can be produced by injection moulding of plastics. Concurrently, a negative pressure is generated in the internal space of the cartridge by moving the vacuum plunger simultaneously in order to prevent or reduce the inclusion of air in the cement dough. The particular advantage of the device according to the invention is that the device can be operated without requiring external aids, such as compressed air-driven vacuum pumps, and without requiring external energy sources, such as compressed air or electrical power. As a result, the device according to the invention can be used autonomously and even under the most difficult surgery conditions. The device according to the invention provides a closed full-prepacked mixing system for price-sensitive markets. 
         [0105]    In the scope of the present invention, it has been found that the supply of the monomer liquid into the cement powder from the underside of the internal space of the cartridge caused by pressure is associated with the monomer liquid migrating in the form of a uniform front from bottom to top. As a result, the air that is present in the intervening spaces between the cement powder particles is displaced and pushed out in upward direction. Concurrently, the air is actively drawn out through the motion of the vacuum plunger. Air inclusions are prevented or at least reduced by this means. In the scope of the present invention, it has been found that a bone cement dough produced with a device according to the invention and a method according to the invention is largely free of air inclusions and is of a quality that corresponds to the quality of a cement dough mixed under a vacuum. 
         [0106]    An exemplary device according to the invention for storage and mixing of polymethylmethacrylate bone cement comprises 
         [0000]    a) a cartridge, whereby a first front side of the internal space of the cartridge is closed by at least one dispensing plunger that is impermeable for powder, and whereby the second front side of the internal space of the cartridge is impermeable for powder, by means of which the internal space of the cartridge, in which cement powder is arranged, bounded by the dispensing plunger and the second front face is formed;
 
b) whereby the internal space of the cartridge is connected to a cylindrical first hollow space in a first hollow cylinder by means of an opening that is impermeable for powder, permeable for liquid and has a liquid-permeable connecting conduit (conduit means)
 
c) whereby a liquid-permeable opening is arranged on the jacket surface of the first hollow cylinder and connects the first hollow space to an opening means for a monomer liquid container that is connected to a monomer liquid container that is arranged above the opening on the jacket surface of the first hollow cylinder;
 
d) a pumping plunger that is arranged in the cylindrical first hollow space and/or a combined pumping-vacuum plunger that can be shifted axially in the first hollow cylinder;
 
e) whereby the dispensing plunger is composed of a sealing plunger and a sterilisation plunger, whereby the sealing plunger is arranged above the sterilisation plunger, and the sealing plunger closes said internal space after being pushed into the internal space of the cartridge, and possesses a gas-permeable feed-through that connects the space below the sealing plunger to the space above the sealing plunger, whereby the feed-through is designed as a vacuum connector on the upper side;
 
f) whereby the first hollow cylinder is closed in gas-tight manner on its front face opposite from the foot part;
 
g) whereby a second hollow space is formed by the upper side of the pumping plunger and an extension of the hollow cylinder, which is closed in gas-tight manner on the front side, and/or a second hollow cylinder such that the upper side of the pumping plunger forms a vacuum plunger and thus a combined pumping-vacuum plunger is formed;
 
h) whereby a gas-permeable feed-through is provided in the front face of the second hollow cylinder, which is closed in gas-tight manner, and the gas-permeable feed-through is connected to the gas-permeable feed-through of the dispensing plunger and/or sealing plunger by means of a gas-permeable connecting means.
 
         [0107]    In this context, the pumping plunger and thus the vacuum plunger can be moved axially in the first and/or second hollow cylinder by means of a driving element that is guided in gas-tight manner. 
         [0108]    The rationale of the idea is that, once a monomer container is opened with an opening device, for example a device in accordance with DE 10 2010 026 496 B4, the monomer liquid flows into the first hollow cylinder due to the action of gravity, [and] is then pressed from same into the cartridge containing cement powder through manual actuation of the pumping plunger. The first hollow cylinder and/or the second hollow cylinder is closed in gas-tight manner on its front face facing away from the foot part. When the vacuum plunger is moved in the direction of the foot part, whereupon the motion of the pumping plunger, in the case of a combined pumping-vacuum plunger, presses the monomer liquid into the internal space of the cartridge, a negative pressure is concurrently generated in the hollow space above the vacuum plunger in the second hollow cylinder. This means that a negative pressure is generated concurrently and is guided via a feed-through and via a gas-permeable connecting means (the vacuum conduit) into the internal space of the cartridge. If, during the motion of the pumping-vacuum plunger, the volume in the hollow space between the vacuum plunger and the connector to the vacuum conduit is larger than the volume of the monomer liquid in the first hollow cylinder to be pressed out, a negative pressure is generated in the first cartridge. This effect can be attained through providing the combined pumping-vacuum plunger to be made of two cylindrical plungers, namely the pumping plunger and the vacuum plunger, whereby the lower cylinder (pumping plunger) has a smaller external diameter than the upper cylinder (vacuum plunger). This means that the combined pumping-vacuum plunger is double-acting. Upon axial motion of the pumping-vacuum plunger, one side of the combined pumping-vacuum plunger has a pumping function for generating a positive pressure and the other side of the pumping-vacuum plunger concurrently generates a negative pressure. 
         [0109]    According to another advantage of devices and methods according to the invention, a monomer transfer due to the expelling motion of the pumping plunger is always ensured to proceed regardless of whether or not the user closed the internal space of the cartridge in gas-tight manner with respect to the pumping plunger and/or vacuum plunger. As a result, the handling safety is increased as compared to previously known full-prepacked mixing systems, in which the transfer of the monomer liquid is effected only through the applied vacuum, which is more or less stable depending on the energy source that is used. 
         [0110]    An exemplary method according to the invention is a method with the exemplary device described above that is characterised by the following steps proceeding in the order given, 
         [0000]    a) the monomer liquid container is opened by actuating the opening means;
 
b) the monomer liquid flows through the opening in the jacket surface of the first hollow cylinder into the hollow space of the first hollow cylinder due to the action of gravity;
 
c) following complete transfer of the monomer liquid into the hollow space of the first hollow cylinder, the pumping plunger and/or the combined pumping-vacuum plunger is pushed by hand in the direction of the foot part of the device;
 
d) whereby the monomer liquid is pushed through the connecting conduit (the conduit means) into the internal space of the cartridge into the cement powder;
 
e) following complete transfer of the monomer liquid from the first hollow space into the internal space of the cartridge, the mixture consisting of cement powder and monomer liquid is mixed by hand by actuating a mixing rod;
 
f) the mixing rod is then pulled upwards;
 
g) the mixing rod is then broken off at a predetermined breakage site; and
 
h) the cartridge is then separated from the foot part.
 
         [0111]    Another exemplary method with the exemplary device described above that is characterised by the following steps proceeding in the order given, 
         [0000]    a) the monomer liquid container is opened by actuating the opening means;
 
b) the monomer liquid flows through the opening in the jacket surface of the first hollow cylinder into the hollow space of the first hollow cylinder due to the action of gravity;
 
c) following complete transfer of the monomer liquid into the first hollow space, a locking mechanism of the pumping plunger and/or of the combined pumping-vacuum plunger is detached whereby a compression spring pushes the pumping plunger and the vacuum and/or the combined pumping-vacuum plunger in the direction of the foot part of the device;
 
d) whereby the monomer liquid is pushed through the connecting conduit (the conduit means) into the internal space of the cartridge into the cement powder and the motion of the vacuum plunger and/or of the combined pumping-vacuum plunger draws air out of the internal space of the cartridge;
 
e) following complete transfer of the monomer liquid from the first hollow space into the internal space of the cartridge, the mixture consisting of cement powder and monomer liquid is mixed by hand by actuating a mixing rod;
 
f) the mixing rod is then pulled upwards;
 
g) the mixing rod is then broken off at a predetermined breakage site; and
 
h) the cartridge is then separated from the foot part.
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0112]    Further exemplary embodiments of the invention shall be illustrated in the following on the basis of nine schematic figures, though without limiting the scope of the invention. In the figures: 
           [0113]      FIG. 1 : shows a schematic perspective view of a device according to the invention as full-prepacked mixing system; 
           [0114]      FIG. 2 : shows the device according to  FIG. 1  in a frontal view with a section plane AA; 
           [0115]      FIG. 3 : shows the device according to  FIGS. 1 and 2  in a schematic cross-sectional view that corresponds to section plane A in accordance with  FIG. 2 ; 
           [0116]      FIG. 4 : shows a detail of the device according to  FIGS. 1, 2, and 3  in a schematic cross-sectional view that corresponds to a section plane parallel to section plane AA according to  FIG. 2 ; 
           [0117]      FIG. 5 : shows a schematic perspective view of an alternative second device according to the invention as full-prepacked mixing system; 
           [0118]      FIG. 6 : shows the device according to  FIG. 5  in a schematic cross-sectional view; 
           [0119]      FIG. 7 : shows a schematic perspective view of an alternative third device according to the invention as full-prepacked mixing system; 
           [0120]      FIG. 8 : shows the device according to  FIG. 7  in a schematic cross-sectional view; and 
           [0121]      FIG. 9 : shows a schematic cross-sectional view of an alternative fourth device according to the invention as full-prepacked mixing system, in which the schematic functional principle of the device is shown. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0122]    Sectioned surfaces are indicated by hatching in the cross-sectional views of  FIGS. 3, 4, 6, 8, and 9 . 
         [0123]      FIGS. 1 to 4  shows schematic depictions of a first device according to the invention that is well-suited for implementing a method according to the invention. In this context,  FIG. 1  shows a schematic perspective view of a device according to the invention as full-prepacked mixing system,  FIG. 2  shows the device according to  FIG. 1  in a frontal view with a section plane AA,  FIG. 3  shows the device according to  FIGS. 1 and 2  in a schematic cross-sectional view according to section plane AA according to  FIG. 2 , and  FIG. 4  shows a detail of said device according to  FIGS. 1, 2, and 3  in a schematic cross-sectional view corresponding to a section plane that is parallel to section plane AA according to  FIG. 2 . 
         [0124]    The device comprises a cartridge  1  that contains a cement powder as starting component of the PMMA bone cement to be produced. The cartridge  1  is closed on the upper side (on the top in  FIGS. 1 and 3 ) by means of a dispensing plunger  2 . The dispensing plunger  2  can be locked against the walls of the cartridge  1 . A mixing rod  4  is guided through a centric feed-through in the dispensing plunger  2  and can be pulled into and out of the cartridge  1  and is supported in the dispensing plunger  2 , and thus in the cartridge  1 , such that it can be rotated. A handle part  6  for manual operation of the mixing rod  4  is attached on the upper end of the mixing rod  4  (on the top in  FIGS. 1, 2, and 3 ). 
         [0125]    The cartridge  1  with the base  10  is attached in detachable manner in the area of a socket  8  on a base  10  of the device. An upper (outer) hollow cylinder  12  is arranged on the upper side of the base  10 , whereby said cylinder and the base are provided as a single part. A rod  14  with a push-button  15  for operation of the rod  14  is guided through a feed-through in a cover plate  16 . The cover plate  16  closes the upper hollow cylinder  12  in upward direction in pressure-tight manner. For this purpose, a sealing ring is provided in the feed-through for the rod  14  by means of which the rod  14  is sealed with respect to the feed-through. The dispensing plunger  2  has a vacuum connector provided in it to which a vacuum conduit  17  is connected that leads into the interior of the upper hollow cylinder  12 . The vacuum connector can be used to evacuate the interior of the cartridge  1  and, theoretically, the vacuum connector can also be used to supply ethylene oxide for sterilisation of the content of the cartridge  1 , when the vacuum conduit  17  is not connected to the vacuum connector and/or before the vacuum conduit  17  is connected to the vacuum connector. 
         [0126]    Moreover, a connecting socket  18  is provided on the base  10  next to the hollow cylinder  12  and is part of a connector  24  of a monomer container  60  of the device. Aside from the connecting socket  18 , the connector  20  for the monomer container  60  further comprises an elastic receptacle  21  for the monomer container  60  and a lid  22 , by means of which the connector  20  for the monomer container  60  can be closed off with respect to the outside after the monomer container  60  was inserted. The monomer container  60  is arranged in the interior of the connector  20  and thus inside the device. The monomer container  60  is a glass ampoule that is filled with a monomer liquid as second component for the PMMA bone cement to be produced. The elastic receptacle  21  consists of rubber or another elastic plastic material. 
         [0127]    Further details of the design of the device are evident from  FIGS. 3 and 4 . The interior of the cartridge  1  is formed by a cylindrical internal space  24  that contains the cement powder as first component. Moreover, the internal space  24  of the cartridge  1  has a mixing facility  26  consisting of multiple mixing vanes  26  arranged in it that is attached to the mixing rod  4  and can be moved in the internal space  24  of the cartridge  1  by means of the mixing rod  4 . The dispensing plunger  2  has a two-part design and consists of a sterilisation plunger  28  (upper part of the dispensing plunger in  FIG. 3 ) and a sealing plunger  30  (lower part of the dispensing plunger in  FIG. 3 ) that is sealed with respect to the internal wall of the internal space  24  by means of a seal  29 . The sealing plunger  30  comprises a gas-permeable, but powder-impermeable pore disc by means of which the internal space  24  can be evacuated. The dispensing plunger  2  has a cylindrical outer circumference and closes tightly against the walls of the internal space  24 . The dispensing plunger  2  can be propelled in the internal space  24  in the direction of a dispensing opening on the floor of the internal space  24  of the cartridge  1  that is situated on the side of the internal space  24  of the cartridge  1  that is opposite to the dispensing plunger  2 . 
         [0128]    For connecting the cartridge  1  to the base  10 , a base connector  34  having an external thread as the connection to the cartridge  1  is provided, in which a powder-impermeable and liquid-permeable filter  32  is arranged. A cartridge connector  36  having an internal thread matching the external thread of the base connector  34  is provided on the side of the internal space  24  of the cartridge  1  that is opposite to the dispensing plunger  2 . The cartridge connector  36  bounds the dispensing opening of the cartridge  1 . The cartridge connector  36  is screwed onto the base connector  34  and closes off tightly with respect to same. 
         [0129]    A connecting conduit  38  connecting the hollow cylinder  12  to the internal space  24  of the cartridge  1  is provided between the hollow cylinder  12  and the internal space  24  of the cartridge  1 . The filter  32  is arranged at the junction into the internal space  24  of the cartridge  1  and prevents cement powder from the internal space  24  of the cartridge  1  from entering the connecting conduit  38 . The connecting conduit  38  forms a loop  40  with a high apex in order to prevent the monomer liquid from flowing uncontrolled through the connecting conduit  38  into the internal space  24  of the cartridge  1 . A small viewing window (not shown) can be provided for visual inspection of the loop  40 . For this purpose, the connecting conduit  38  must be transparent in the region of the loop  40 . 
         [0130]    The socket  8 , base  10 , and connecting socket  18  for the monomer container  60  are produced, as a single part, from a plastic material, for example by means of injection moulding. The connecting conduit  38  merges into a hollow space  41  in a lower hollow cylinder  42 , whereby the lower (inner) hollow cylinder  42  has a smaller internal diameter than the upper (outer) hollow cylinder  12 . The lower hollow cylinder  42  is bounded, on the underside (on the bottom in  FIG. 3 ), by means of a funnel-shaped floor  43  that tapers steadily downwards. This ensures that the monomer liquid can flow and/or be pushed completely out of the lower hollow cylinder  42 . The lower hollow cylinder  42  has a pumping plunger  44  arranged in it that fits on the inside and can be pressed and/or pushed into the interior of the lower hollow cylinder  42  in the direction of the funnel-shaped floor  43  (downwards in  FIG. 3 ). 
         [0131]    The pumping plunger  44  is formed by a hollow body made of a plastic material and is formed on the lower surface  45  as a negative image of the floor  43  of the lower hollow cylinder  42 . The pumping plunger  44  is sealed with respect to the internal wall of the lower hollow cylinder  42  by means of a seal  53  and is supported such as to be mobile in longitudinal direction (downwards in  FIG. 3 ) in the lower hollow cylinder  42 . 
         [0132]    An open hollow space  46 , in which a vacuum plunger  47  is arranged such as to be axially mobile, is provided in the interior of the upper hollow cylinder  12 . The vacuum plunger  47  is sealed with respect to the internal wall of the upper hollow cylinder  12  by means of a seal  48 . As a result, the vacuum plunger  47  separates, in upward direction, an upper closed hollow space  49  that is bounded by the cover plate  16 , the internal wall of the upper hollow cylinder  12 , and by the vacuum plunger  47 . In contrast, openings  50  are provided in the floor of the open lower hollow space  46 . The upper closed hollow space  49  is connected to the vacuum conduit  17  by means of a connector  52 . The vacuum plunger  47  is affixed to the pumping plunger  44 . In the present embodiment, it is also feasible to provide the vacuum plunger  47  and the pumping plunger  44  in a one-part design. 
         [0133]    A junction  54  of the connector  20  for the monomer container  60  into the lower hollow cylinder  42  and/or the hollow space  41  is provided on a jacket surface of the lower hollow cylinder  42 , right below the lower surface  45  of the pumping plunger  44 . The junction  54  forms a conduit means for the monomer liquid such that the junction  54  can be considered to be part of a connecting conduit  38 ,  40  for the monomer liquid, in which the lower hollow cylinder  42  is arranged. 
         [0134]    The connector  20  for the monomer container  60  has a screen  56  or filter  56  arranged in it that can be used to trap fragments and parts of the opened monomer container  60 . An inclined floor surface  58  that is inclined in the direction of the junction  54  is provided in the connecting socket  18  below the screen  56  and/or filter  56 . As a result, all of the monomer liquid can flow from the monomer container  60  through the junction  54  into the lower hollow cylinder  42 . 
         [0135]    The monomer container  60  is a glass ampoule  60  with an ampoule head  62  that can be broken off and a neck that can be broken open, whereby the neck connects the ampoule head  62  to the body of the ampoule  60 . Due to the elasticity of the receptacle  21  for the monomer container  60  and due to the receptacle  21  being thicker in the area of the neck, the head  62  of the monomer container  60  can be broken off by bending the receptacle  21  with the monomer container  60  in it. Accordingly, the receptacle  21  of appropriate shape, in particular being thicker in the area of the neck, forms an opening means  21  for opening the monomer container  60 . Other opening means for shearing off the head  62  of the monomer container  60  can be implemented just as well. 
         [0136]    A method according to the invention can be implemented with the device according to  FIGS. 1 to 4 , for example as follows. The base  10  of the device is placed on a table or any other fitting level support. The monomer container  60  is opened by kinking the elastic receptacle  21  by breaking off and/or breaking open the head  62 . The monomer liquid from the monomer container  60  flows through the screen  54  and/or the filter  54 , whereby fragments of the monomer container  60  are retained. The inclined floor surface  58  guides the monomer liquid through the junction  54  into the lower hollow cylinder  42  and/or the hollow space  41 . The free hollow space  41  of the lower hollow cylinder  42  is getting filled completely with the monomer liquid, since the monomer container  60  contains more monomer liquid than the combination of the lower hollow cylinder  42  and/or the hollow space  41  and the connecting conduit  38  up to the loop  40  can take up. Enclosed air escapes through the junction  54  since the junction is situated at the highest point of the space bounded by the hollow cylinder  42 , the floor  45  of the pumping plunger  44 , and the connecting conduit  38  up to just below the loop  40 . In this context, the monomer liquid cannot flow beyond the apex of the loop  40  since the apex is situated clearly above the junction  54  and, in addition, the apex is arranged above the liquid level of the monomer liquid in the connector  20  such that the monomer liquid will not rise this high without being exposed to a pressure. 
         [0137]    Subsequently, a manual pressure is exerted in the direction of the base  10  by the user by means of the push-button  15  and thus by means of the rod  14 . As a result, the vacuum plunger  47  is being pushed downwards in the hollow space  46  and the pumping plunger  44  is being pushed into the hollow cylinder  42  and/or the hollow space  41 . The pumping plunger  44  can be pushed into the hollow cylinder  42  and/or the hollow space  41  either completely or partially in order to transfer and/or press the desired amount of monomer liquid from the hollow cylinder  42  through the connecting conduit  38  into the internal space  24  of the cartridge  1 . The amount of monomer liquid that is pressed in can be adjusted by varying the depth to which the pumping plunger  44  is being pushed into the hollow cylinder  42 . For this purpose, markings (not shown) can be provided on the outside of the rod  14 . The monomer liquid is being pressed through the filter  32  into the internal space  24  of the cartridge  1 , where it rises and mixes with the cement powder stored in the internal space  24  of the cartridge  1 . 
         [0138]    Concurrently, the motion of the vacuum plunger  47  enlarges the hollow space  49  between the vacuum plunger  47  and the cover plate  46  in the upper hollow cylinder  12 . As a result, the gas pressure in the hollow space  49  decreases. The decrease in pressure is transmitted by means of the vacuum conduit  17  and the vacuum connector of the sealing plunger  30  as well as through the pore filter of the sterilisation plunger  28  into the internal space  24  of the cartridge  1 . As a result, the internal space  24  of the cartridge  1  is being evacuated through the motion of the vacuum plunger  47  and/or of the plungers  44 ,  47 . Since the vacuum plunger  47  has a larger diameter than the pumping plunger  44 , the volume of monomer liquid that is pushed out of the hollow space  41  into the internal space  24  of the cartridge  1  is smaller than the amount of gas that is evacuated from the internal space of the cartridge  1  through the enlarging volume in the hollow space  49 . Therefore, the pressure in the internal space of the cartridge  1  decreases when the vacuum plunger  47  and the pumping plunger  44  are being pushed in. 
         [0139]    Once the desired amount of monomer liquid has been filled into the internal space  24  of the cartridge  1 , the monomer liquid and the cement powder are being mixed by pushing-in, pulling-out and rotating the mixing facility  26  and/or the mixing rod  4  by means of the handle part  6 , and the cement dough and/or the PMMA bone cement is thus being mixed. After the mixing is completed, the mixing rod  4  is pulled out of the internal space  24  of the cartridge  1  up to the limit stop and broken off to make sure that it does not interfere later on. If applicable, a locking mechanism of the dispensing plunger  2  can be detached. Subsequently, the vacuum conduit  17  is disconnected from the vacuum connector of the sealing plunger  30  and the cartridge  1  is unscrewed from the base  10 . A dispensing tube (not shown) can be screwed onto the internal thread on the cartridge connector  36 . Subsequently, the ready-mixed bone cement can be expelled from the internal space  24  of the cartridge  1  through the dispensing opening and the dispensing tube by pressing the dispensing plunger  2  inwards, and the ready-mixed bone cement can be applied. 
         [0140]      FIGS. 5 and 6  show schematic depictions of a second alternative device according to the invention that is well-suited for implementing a method according to the invention. In this context,  FIG. 5  shows a schematic perspective view of the alternative device according to the invention as full-prepacked mixing system, and  FIG. 6  shows the device according to  FIG. 5  in a schematic cross-sectional view. 
         [0141]    The device comprises a cartridge  101  that contains a cement powder as starting component of the PMMA bone cement to be produced. The cartridge  101  is closed on the upper side (on the top in  FIGS. 5 and 6 ) by means of a dispensing plunger  102 . The dispensing plunger  102  can be locked against the walls of the cartridge  101 . A mixing rod  104  is guided through a centric feed-through in the dispensing plunger  102  and can be pulled into and out of the cartridge  101  and is supported in the dispensing plunger  102 , and thus in the cartridge  101 , such that it can be rotated. A handle part  106  for manual operation of the mixing rod  104  is attached on the upper end of the mixing rod  104  (on the top in  FIGS. 5 and 6 ). 
         [0142]    The cartridge  101  with the base  110  is attached in detachable manner in the area of a socket  108  on a base  110  of the device. An upper (outer) hollow cylinder  112  is arranged on the upper side of the base  110 , whereby said cylinder and the base are provided as a single part. A locked-in rod  114  with a securing mechanism  115  for unlocking the rod  114  and/or for triggering the device is guided through a feed-through in a cover plate  116 . The cover plate  116  closes the upper hollow cylinder  112  in upward direction in pressure-tight manner. For this purpose, a sealing ring is provided in a seat of the securing mechanism  115  by means of which the securing mechanism  115  is sealed with respect to the seat. 
         [0143]    The dispensing plunger  102  has a vacuum connector provided in it to which a vacuum conduit  117  is connected that leads into the interior of the upper hollow cylinder  112 . The vacuum connector can be used to evacuate the interior of the cartridge  101  and, theoretically, the vacuum connector can also be used to supply ethylene oxide for sterilisation of the content of the cartridge  101 , when the vacuum conduit  117  is not connected to the vacuum connector and/or before the vacuum conduit  117  is connected to the vacuum connector. 
         [0144]    Moreover, a connecting socket  118  is provided on the base  110  next to the hollow cylinder  112  and is part of a connector  120  for a monomer container  160  of the device. Aside from the connecting socket  118 , the connector  120  for the monomer container  160  further comprises an elastic receptacle  121  for the monomer container  160  and a lid  122 , by means of which the connector  120  for the monomer container  160  can be closed off with respect to the outside after the monomer container  160  was inserted. The monomer container  160  is arranged in the interior of the connector  120  and thus inside the device. The monomer container  160  is a glass ampoule that is filled with a monomer liquid as second component for the PMMA bone cement to be produced. The elastic receptacle  121  consists of rubber or another elastic plastic material. 
         [0145]    Further details of the design of the device are evident from  FIG. 6 . The interior of the cartridge  101  is formed by a cylindrical internal space  124  that contains the cement powder as first component. Moreover, the internal space  124  of the cartridge  101  has a mixing facility  126  consisting of multiple mixing vanes  126  arranged in it that is attached to the mixing rod  104  and can be moved in the internal space  124  of the cartridge  101  by means of the mixing rod  104 . The dispensing plunger  102  has a two-part design and consists of a sterilisation plunger  128  (upper part of the dispensing plunger in  FIG. 6 ) and a sealing plunger  130  (lower part of the dispensing plunger in  FIG. 6 ) that is sealed with respect to the internal wall of the internal space  124  by means of a seal  129 . The sealing plunger  130  comprises a gas-permeable, but powder-impermeable pore disc by means of which the internal space  124  can be evacuated. The dispensing plunger  102  has a cylindrical outer circumference and closes tightly against the walls of the internal space  124 . The dispensing plunger  102  can be propelled in the internal space  124  in the direction of a dispensing opening on the floor of the internal space  124  of the cartridge  101  that is situated on the side of the internal space  124  of the cartridge  101  that is opposite to the dispensing plunger  102 . 
         [0146]    For connecting the cartridge  101  to the base  110 , a base connector  134  having an external thread as the connection to the cartridge  101  is provided, in which a powder-impermeable and liquid-permeable filter  132  is arranged. A cartridge connector  136  having an internal thread matching the external thread of the base connector  134  is provided on the side of the internal space  124  of the cartridge  101  that is opposite to the dispensing plunger  102 . The cartridge connector  136  bounds the dispensing opening of the cartridge  101 . The cartridge connector  136  is screwed onto the base connector  134  and closes off tightly with respect to same. 
         [0147]    A connecting conduit  138  connecting the hollow cylinder  112  to the internal space  124  of the cartridge  101  is provided between the hollow cylinder  112  and the internal space  124  of the cartridge  101 . The filter  132  is arranged at the junction into the internal space  124  of the cartridge  101  and prevents cement powder from the internal space  124  of the cartridge  101  from entering the connecting conduit  138 . The connecting conduit  138  forms a loop  140  with a high apex in order to prevent the monomer liquid from flowing uncontrolled through the connecting conduit  138  into the internal space  124  of the cartridge  101 . A small viewing window (not shown) can be provided for visual inspection of the loop  140 . For this purpose, the connecting conduit  138  must be transparent in the region of the loop  140 . 
         [0148]    The socket  108 , base  110 , and connecting socket  118  for the monomer container  160  are produced, as a single part, from a plastic material, for example by means of injection moulding. The connecting conduit  138  merges into a hollow space  141  in a lower hollow cylinder  142 , whereby the lower (inner) hollow cylinder  142  has a smaller internal diameter than the upper (outer) hollow cylinder  112 . The lower hollow cylinder  142  is bounded, on the underside (on the bottom in  FIG. 6 ), by means of a funnel-shaped floor  143  that tapers steadily downwards. This ensures that the monomer liquid can flow and/or be pushed completely out of the lower hollow cylinder  142 . The lower hollow cylinder  142  has a pumping plunger  144  arranged in it that fits on the inside and can be pressed and/or pushed into the interior of the lower hollow cylinder  142  in the direction of the funnel-shaped floor  143  (downwards in  FIG. 6 ). 
         [0149]    The pumping plunger  144  is formed by a hollow body made of a plastic material and is formed on the lower surface  145  as a negative image of the floor  143  of the lower hollow cylinder  142 . The pumping plunger  144  is sealed with respect to the internal wall of the lower hollow cylinder  142  by means of a seal  153  and is supported such as to be mobile in longitudinal direction (downwards in  FIG. 6 ) in the lower hollow cylinder  142 . 
         [0150]    An open hollow space  146 , in which a vacuum plunger  147  is arranged such as to be axially mobile, is provided in the interior of the upper hollow cylinder  112 . The vacuum plunger  147  is sealed with respect to the internal wall of the upper hollow cylinder  112  by means of a seal  148 . As a result, the vacuum plunger  147  separates, in upward direction, an upper closed hollow space  149  that is bounded by the cover plate  116 , the internal wall of the upper hollow cylinder  112 , the securing mechanism  115 , and by the vacuum plunger  147 . In contrast, openings  150  are provided in the floor of the open lower hollow space  146 . A tensioned compression spring  151  arranged to surround the rod  114  is provided in the interior of the hollow space  149  of the upper hollow cylinder  112 . The tension of the compression spring  151  is maintained by the rod  114  between the cover plate  116  and the upper side of the vacuum plunger  147  that is locked by means of the cover plate  116 . The upper closed hollow space  149  is connected to the vacuum conduit  117  by means of a connector  152 . The vacuum plunger  147  is affixed to the pumping plunger  144 . In the present embodiment, it is also feasible to provide the vacuum plunger  147  and the pumping plunger  144  in a one-part design. 
         [0151]    A junction  154  of the connector  120  for the monomer container  160  into the lower hollow cylinder  142  and/or the hollow space  141  is provided on a jacket surface of the lower hollow cylinder  142 , right below the lower surface  145  of the pumping plunger  144 . The junction  154  forms a conduit means for the monomer liquid such that the junction  154  can be considered to be part of a connecting conduit  138 ,  140  for the monomer liquid, in which the lower hollow cylinder  142  is arranged. 
         [0152]    The connector  120  for the monomer container  160  has a screen  156  or filter  156  arranged in it that can be used to trap fragments and parts of the opened monomer container  160 . An inclined floor surface  158  that is inclined in the direction of the junction  154  is provided in the connecting socket  118  below the screen  156  and/or filter  156 . As a result, all of the monomer liquid can flow from the monomer container  160  through the junction  154  into the lower hollow cylinder  142 . 
         [0153]    The monomer container  160  is a glass ampoule  160  with an ampoule head  162  that can be broken off and a neck that can be broken open, whereby the neck connects the ampoule head  162  to the body of the ampoule  160 . Due to the elasticity of the receptacle  121  for the monomer container  160  and due to the receptacle  121  being thicker in the area of the neck, the head  162  of the monomer container  160  can be broken off by bending the receptacle  121  with the monomer container  160  in it. Accordingly, the receptacle  121  of appropriate shape, in particular being thicker in the area of the neck, forms an opening means  121  for opening the monomer container  160 . Other opening means for shearing off the head  162  of the monomer container  160  can be implemented just as well. 
         [0154]    A method according to the invention can be implemented with the alternative second device according to  FIGS. 5 and 6 , for example as follows. The base  110  of the device is placed on a table or any other fitting level support. The monomer container  160  is opened by kinking the elastic receptacle  121  by breaking off and/or breaking open the head  162 . The monomer liquid from the monomer container  160  flows through the screen  156  and/or the filter  156 , whereby fragments of the monomer container  160  are retained. The inclined floor surface  158  guides the monomer liquid through the junction  154  into the lower hollow cylinder  142  and/or the hollow space  141 . The free hollow space  141  of the lower hollow cylinder  142  is getting filled completely with the monomer liquid, since the monomer container  160  contains more monomer liquid than the combination of the lower hollow cylinder  142  and/or the hollow space  141  and the connecting conduit  138  up to the loop  140  can take up. Enclosed air escapes through the junction  154  since the junction is situated at the highest point of the space bounded by the hollow cylinder  142 , the floor  145  of the pumping plunger  144 , and the connecting conduit  138  up to just below the loop  140 . In this context, the monomer liquid cannot flow beyond the apex of the loop  140  since the apex is situated clearly above the junction  154  and, in addition, the apex is arranged above the liquid level of the monomer liquid in the connector  120  such that the monomer liquid will not rise this high without being exposed to a pressure. 
         [0155]    The securing mechanism  115  can be pushed downward into the seat by compressing two flat handle levers that are arranged on the securing mechanism  115  and project out of the seat in the cover plate  116 . As a result, the securing mechanism  115  slides onto the upper end of the rod  114  and multiple snap-in hooks that are arranged on the upper end of the rod  114  become deformed. As a result, the rod  114  is rendered freely mobile and the rod  114  is accelerated instantaneously, together with the vacuum plunger  147  and the pumping plunger  144 , in the direction of the base  110  by the tensioned compression spring  155 . 
         [0156]    The compression spring  151  pushes the vacuum plunger  147  downwards in the hollow space  146 . The monomer liquid from the hollow space  141  is pressed through the connecting conduit  138  and the filter  132  into the internal space  124  of the cartridge  101 , where it rises and mixes with the cement powder stored in the internal space  124  of the cartridge  101 . 
         [0157]    Concurrently, the motion of the vacuum plunger  147  enlarges the hollow space  149  between the vacuum plunger  147  and the cover plate  146  in the upper hollow cylinder  112 . As a result, the gas pressure in the hollow space  149  decreases. The decrease in pressure is transmitted by means of the vacuum conduit  117  and the vacuum connector of the sealing plunger  130  as well as through the pore filter of the sterilisation plunger  128  into the internal space  124  of the cartridge  101 . As a result, the internal space  124  of the cartridge  101  is being evacuated through the motion of the vacuum plunger  147  and/or of the plungers  144 ,  147 . Since the vacuum plunger  147  has a larger diameter than the pumping plunger  144 , the volume of monomer liquid that is pushed out of the hollow space  141  into the internal space  124  of the cartridge  101  is smaller than the amount of gas that is evacuated from the internal space of the cartridge  101  through the enlarging volume in the hollow space  149 . Therefore, the pressure in the internal space of the cartridge  101  decreases when the vacuum plunger  147  and the pumping plunger  144  are being pushed in. 
         [0158]    Once the desired amount of monomer liquid has been filled into the internal space  124  of the cartridge  101 , the monomer liquid and the cement powder are being mixed by pushing-in, pulling-out and rotating the mixing facility  126  and/or the mixing rod  104  by means of the handle part  6 , and the cement dough and/or the PMMA bone cement is thus being mixed. After the mixing is completed, the mixing rod  104  is pulled out of the internal space  124  of the cartridge  101  up to the limit stop and broken off to make sure that it does not interfere later on. If applicable, a locking mechanism of the dispensing plunger  102  can be detached. Subsequently, the vacuum conduit  117  is disconnected from the vacuum connector of the sealing plunger  130  and the cartridge  101  is unscrewed from the base  110 . A dispensing tube (not shown) can be screwed onto the internal thread on the cartridge connector  136 . Subsequently, the ready-mixed bone cement can be expelled from the internal space  124  of the cartridge  101  through the dispensing opening and the dispensing tube by pressing the dispensing plunger  102  inwards, and the ready-mixed bone cement can be applied. 
         [0159]      FIGS. 7 and 8  show schematic depictions of a third alternative device according to the invention that is well-suited for implementing a method according to the invention. In this context,  FIG. 7  shows a schematic perspective view of the alternative device according to the invention as full-prepacked mixing system, and  FIG. 8  shows the device according to  FIG. 7  in a schematic cross-sectional view. 
         [0160]    The third alternative device has a similar design as the first device according to  FIGS. 1 to 4  and the second alternative device according to  FIGS. 5 and 6  and comprises a cartridge  201  that contains a cement powder as first starting component of the PMMA bone cement to be produced. The cartridge  201  is closed on the upper side (on the top in  FIGS. 7 and 8 ) by means of a dispensing plunger  202 . The dispensing plunger  202  can be locked against the walls of the cartridge  201 . A mixing rod  204  is guided through a centric feed-through in the dispensing plunger  202  and can be pulled into and out of the cartridge  201  and is supported in the dispensing plunger  202 , and thus in the cartridge  201 , such that it can be rotated. A handle part  206  for manual operation of the mixing rod  204  is attached on the upper end of the mixing rod  204  (on the top in  FIGS. 7 and 8 ). 
         [0161]    The cartridge  201  with the base  210  is attached in detachable manner in the area of a socket  208  on a base  210  of the device. An upper (outer) hollow cylinder  212  is arranged on the upper side of the base  210 , whereby said cylinder and the base are provided as a single part. A rod  214  with a hood  215  for operation of the rod  214  is guided through a feed-through in a cover plate  216 . The cover plate  216  closes the upper hollow cylinder  212  in upward direction in pressure-tight manner. For this purpose, a sealing ring is provided in the feed-through for the rod  214  by means of which the rod  214  is sealed with respect to the feed-through. 
         [0162]    The dispensing plunger  202  has a vacuum connector provided in it to which a vacuum conduit  217  is connected that leads into the interior of the upper hollow cylinder  212 . The vacuum connector can be used to evacuate the interior of the cartridge  201  and, theoretically, the vacuum connector can also be used to supply ethylene oxide for sterilisation of the content of the cartridge  201 , when the vacuum conduit  217  is not connected to the vacuum connector and/or before the vacuum conduit  217  is connected to the vacuum connector. 
         [0163]    Moreover, a connecting socket  218  is provided on the base  210  next to the hollow cylinder  212  and is part of a connector  220  for a monomer container  260  of the device. Aside from the connecting socket  218 , the connector  220  for the monomer container  260  further comprises an elastic receptacle  221  for the monomer container  260  and a lid  222 , by means of which the connector  220  for the monomer container  260  can be closed off with respect to the outside after the monomer container  260  was inserted. The monomer container  260  is arranged in the interior of the connector  220  and thus inside the device. The monomer container  260  is a glass ampoule that is filled with a monomer liquid as second component for the PMMA bone cement to be produced. The elastic receptacle  221  consists of rubber or another elastic plastic material. Multiple ventilation passages  223  are arranged in the lid  222  and in the thickened part of the receptacle  220 . The purpose of the ventilation passages  223  is to allow the monomer liquid to readily flow out of the opened ampoule  260  and/or the opened monomer container  260 . In this context, the ventilation passages  223  prevent a negative pressure from being generated in the area of the lid  222  of the monomer container  220  that would counteract the flow of the monomer liquid. 
         [0164]    Further details of the design of the device are evident from  FIG. 8 . The interior of the cartridge  201  is formed by a cylindrical internal space  224  that contains the cement powder as first component. Moreover, the internal space  224  of the cartridge  201  has a mixing facility  226  consisting of multiple mixing vanes  226  arranged in it that is attached to the mixing rod  204  and can be moved in the internal space  224  of the cartridge  201  by means of the mixing rod  204 . The dispensing plunger  202  has a two-part design and consists of a sterilisation plunger  228  (upper part of the dispensing plunger in  FIG. 8 ) and a sealing plunger  230  (lower part of the dispensing plunger in  FIG. 8 ) that is sealed with respect to the internal wall of the internal space  224  by means of a seal  229 . The sealing plunger  230  comprises a gas-permeable, but powder-impermeable pore disc by means of which the internal space  224  can be evacuated. The dispensing plunger  202  has a cylindrical outer circumference and closes tightly against the walls of the internal space  224 . The dispensing plunger  202  can be propelled in the internal space  224  in the direction of a dispensing opening on the floor of the internal space  224  of the cartridge  201  that is situated on the side of the internal space  224  of the cartridge  201  that is opposite to the dispensing plunger  202 . 
         [0165]    For connecting the cartridge  201  to the base  210 , a base connector  234  having an external thread as the connection to the cartridge  201  is provided, in which a powder-impermeable and liquid-permeable filter  232  is arranged. A cartridge connector  236  having an internal thread matching the external thread of the base connector  234  is provided on the side of the internal space  224  of the cartridge  201  that is opposite to the dispensing plunger  202 . The cartridge connector  236  bounds the dispensing opening of the cartridge  201 . The cartridge connector  236  is screwed onto the base connector  234  and closes off tightly with respect to same. 
         [0166]    A connecting conduit  238  connecting the hollow cylinder  212  to the internal space  224  of the cartridge  201  is provided between the hollow cylinder  212  and the internal space  224  of the cartridge  201 . The filter  232  is arranged at the junction into the internal space  224  of the cartridge  201  and prevents cement powder from the internal space  224  of the cartridge  201  from entering the connecting conduit  238 . The connecting conduit  238  is guided, in part, in a housing  239  that contains viewing windows. The connecting conduit  238  forms a loop  240  with a high apex in the housing  239  in order to prevent the monomer liquid from flowing uncontrolled through the connecting conduit  238  into the internal space  224  of the cartridge  201 . The viewing windows in the housing  239  are provided for visual control of the loop  240 . Moreover, they allow the liquid level of the monomer liquid in the connecting conduit  238  to be determined. A scale is attached at one of the viewing windows for this purpose. To be able to see the liquid level, the connecting conduit  238  must be transparent in the region of the loop  240 . 
         [0167]    The socket  208 , base  210 , housing  239 , and connecting socket  218  for the monomer container  260  are produced, as a single part, from a plastic material, for example by means of injection moulding. The connecting conduit  238  merges into a hollow space  241  in a lower hollow cylinder  242 , whereby the lower (inner) hollow cylinder  242  has a smaller internal diameter than the upper (outer) hollow cylinder  212 . The lower hollow cylinder  242  is bounded, on the underside (on the bottom in  FIG. 8 ), by means of a funnel-shaped floor  243  that tapers steadily downwards. This ensures that the monomer liquid can flow and/or be pushed completely out of the lower hollow cylinder  242 . The lower hollow cylinder  242  has a pumping plunger  244  arranged in it that fits on the inside and can be pressed and/or pushed into the interior of the lower hollow cylinder  242  in the direction of the funnel-shaped floor  243  (downwards in  FIG. 8 ). 
         [0168]    The pumping plunger  244  is formed by a hollow body made of a plastic material and is formed on the lower surface  245  as a negative image of the floor  243  of the lower hollow cylinder  242 . The pumping plunger  244  is sealed with respect to the internal wall of the lower hollow cylinder  242  by means of a seal  253  and is supported such as to be mobile in longitudinal direction (downwards in  FIG. 8 ) in the lower hollow cylinder  242 . 
         [0169]    An open hollow space  246 , in which a vacuum plunger  247  is arranged such as to be axially mobile, is provided in the interior of the upper hollow cylinder  212 . The vacuum plunger  247  is sealed with respect to the internal wall of the upper hollow cylinder  212  by means of a seal  248 . As a result, the vacuum plunger  247  separates, in upward direction, an upper closed hollow space  249  that is bounded by the cover plate  216 , the internal wall of the upper hollow cylinder  212 , the securing mechanism  215 , and by the vacuum plunger  247 . In contrast, openings  250  are provided in the floor of the open lower hollow space  246 . The upper closed hollow space  249  is connected to the vacuum conduit  217  by means of a connector  252 . A vertical slit through which the flexible vacuum conduit  217  is guided is provided in the hood  215 . When the hood  215  is pushed downward in the direction of the base  210 , the vacuum conduit  217  slides in said slit. The vacuum plunger  247  is affixed to the pumping plunger  244 . In the present embodiment, it is also feasible to provide the vacuum plunger  247  and the pumping plunger  244  in a one-part design. 
         [0170]    A junction  254  of the connector  220  for the monomer container  260  into the lower hollow cylinder  242  and/or the hollow space  241  is provided on a jacket surface of the lower hollow cylinder  242 , right below the lower surface  245  of the pumping plunger  244 . The junction  254  forms a conduit means for the monomer liquid such that the junction  254  can be considered to be part of a connecting conduit  238 ,  240  for the monomer liquid, in which the lower hollow cylinder  242  is arranged. 
         [0171]    The connector  220  for the monomer container  260  has a screen  256  or filter  256  arranged in it that can be used to trap fragments and parts of the opened monomer container  260 . An inclined floor surface  258  that is inclined in the direction of the junction  254  is provided in the connecting socket  218  below the screen  256  and/or filter  256 . As a result, all of the monomer liquid can flow from the monomer container  260  through the junction  254  into the lower hollow cylinder  242 . 
         [0172]    The monomer container  260  is a glass ampoule  260  with an ampoule head  262  that can be broken off and a neck that can be broken open, whereby the neck connects the ampoule head  262  to the body of the ampoule  260 . Due to the elasticity of the receptacle  221  for the monomer container  260  and due to the receptacle  221  being thicker in the area of the neck, the head  262  of the monomer container  260  can be broken off by bending the receptacle  221  with the monomer container  260  in it. Accordingly, the receptacle  221  of appropriate shape, in particular being thicker in the area of the neck, forms an opening means  221  for opening the monomer container  260 . Other opening means for shearing off the head  262  of the monomer container  260  can be implemented just as well. 
         [0173]    A method according to the invention can be implemented with the alternative second device according to  FIGS. 7 and 8 , for example as follows. The base  210  of the device is placed on a table or any other fitting level support. The monomer container  260  is opened by kinking the elastic receptacle  221  by breaking off and/or breaking open the head  262 . The monomer liquid from the monomer container  260  flows through the screen  256  and/or the filter  256 , whereby fragments of the monomer container  260  are retained. The inclined floor surface  258  guides the monomer liquid through the junction  254  into the lower hollow cylinder  242  and/or the hollow space  241 . The ventilation passages  223  allow air from outside to flow along such that the monomer liquid can readily flow into the hollow space  241 . The free hollow space  241  of the lower hollow cylinder  242  is getting filled completely with the monomer liquid, since the monomer container  260  contains more monomer liquid than the combination of the lower hollow cylinder  242  and/or the hollow space  241  and the connecting conduit  238  up to the loop  240  can take up. Enclosed air escapes through the junction  254  since the junction is situated at the highest point of the space bounded by the hollow cylinder  242 , the floor  245  of the pumping plunger  244 , and the connecting conduit  238  up to just below the loop  240 . In this context, the monomer liquid cannot flow beyond the apex of the loop  240  since the apex is situated clearly above the junction  254  and, in addition, the apex is arranged above the liquid level of the monomer liquid in the connector  220  such that the monomer liquid will not rise this high without being exposed to a pressure. 
         [0174]    Subsequently, a manual pressure is exerted in the direction of the base  210  by the user by means of the hood  215  and thus by means of the rod  214 . As a result, the vacuum plunger  247  is being pushed downwards in the hollow space  246  and the pumping plunger  244  is being pushed into the hollow cylinder  242  and/or the hollow space  241 . The pumping plunger  244  can be pushed into the hollow cylinder  242  and/or the hollow space  241  either completely or partially in order to transfer and/or press the desired amount of monomer liquid from the hollow cylinder  242  through the connecting conduit  238  into the internal space  224  of the cartridge  201 . In this context, the transition of the monomer liquid and the liquid level of the monomer liquid in the hollow space  241  can be controlled by means of the viewing windows and the scale in the housing  239 . The amount of monomer liquid that is pressed in can be adjusted by varying the depth to which the pumping plunger  244  is being pushed into the hollow cylinder  242 . For this purpose, markings (not shown) can be provided on the outside of the hood  215 . The monomer liquid is being pressed through the filter  232  into the internal space  224  of the cartridge  201 , where it rises and mixes with the cement powder stored in the internal space  224  of the cartridge  201 . 
         [0175]    Concurrently, the motion of the vacuum plunger  247  enlarges the hollow space  249  between the vacuum plunger  247  and the cover plate  246  in the upper hollow cylinder  212 . As a result, the gas pressure in the hollow space  249  decreases. The decrease in pressure is transmitted by means of the vacuum conduit  217  and the vacuum connector of the sealing plunger  230  as well as through the pore filter of the sterilisation plunger  228  into the internal space  224  of the cartridge  201 . As a result, the internal space  224  of the cartridge  201  is being evacuated through the motion of the vacuum plunger  247  and/or of the plungers  244 ,  247 . Since the vacuum plunger  247  has a larger diameter than the pumping plunger  244 , the volume of monomer liquid that is pushed out of the hollow space  241  into the internal space  224  of the cartridge  201  is smaller than the amount of gas that is evacuated from the internal space of the cartridge  201  through the enlarging volume in the hollow space  249 . Therefore, the pressure in the internal space of the cartridge  201  decreases when the vacuum plunger  247  and the pumping plunger  244  are being pushed in. 
         [0176]    Once the desired amount of monomer liquid has been filled into the internal space  224  of the cartridge  201 , the monomer liquid and the cement powder are being mixed by pushing-in, pulling-out and rotating the mixing facility  226  and/or the mixing rod  204  by means of the handle part  206 , and the cement dough and/or the PMMA bone cement is thus being mixed. After the mixing is completed, the mixing rod  204  is pulled out of the internal space  224  of the cartridge  201  up to the limit stop and broken off to make sure that it does not interfere later on. If applicable, a locking mechanism of the dispensing plunger  202  can be detached. Subsequently, the vacuum conduit  217  is disconnected from the vacuum connector of the sealing plunger  230  and the cartridge  201  is unscrewed from the base  210 . A dispensing tube (not shown) can be screwed onto the internal thread on the cartridge connector  236 . Subsequently, the ready-mixed bone cement can be expelled from the internal space  224  of the cartridge  201  through the dispensing opening and the dispensing tube by pressing the dispensing plunger  202  inwards, and the ready-mixed bone cement can be applied. 
         [0177]      FIG. 9  shows a schematic cross-sectional view of an alternative fourth device according to the invention as full-prepacked mixing system, in which the schematic functional principle of the device is shown. It is self-evident that the parts of the fourth device according to the invention are connected to each other, in some case are connected to each other in detachable manner. Accordingly, the basic design can be presumed to be largely analogous to that of the three previous exemplary embodiments according to  FIGS. 1 to 8 . 
         [0178]    The device comprises a cartridge  301  (on the left in  FIG. 9 ) with an internal space  324  that contains a cement powder as first starting component for the production of the bone cement. The cartridge  301  is closed on the upper side by means of a dispensing plunger  302  that is axially mobile in the cartridge  301 . A mixing rod  304 , which is guided through the dispensing plunger  302  such as to be mobile, is connected to a mixing facility  326  in the internal space  324  of the cartridge  301 . 
         [0179]    The device further comprises a first hollow cylinder  342  and a second hollow cylinder  312 , which, unlike the previous exemplary embodiments, are arranged separate with respect to each other and/or adjoining each other. A hollow space  341  and a pumping plunger  344  that is mobile in the hollow space  341  are provided in the first hollow cylinder  342 . The pumping plunger  344  comprises a lower surface  345  that fits the funnel-shaped inclined floor  343  of the hollow space  341 . The centre of the funnel-shaped floor  343  has a drain provided on it to which a connecting conduit  338  is connected that connects the hollow space  341  for the pumping plunger  344  to the internal space  324  of the cartridge  301  on the underside thereof. A powder-impermeable and liquid-permeable filter  332  is provided in this connection as well. In analogy to the previous exemplary embodiments, the connecting conduit  338  comprises a loop  340  at a fitting height. 
         [0180]    The second hollow cylinder  312  is intended for generating a negative pressure. For this purpose, an axially mobile vacuum plunger  347  is arranged in the hollow space  341 , which is open on its lower side, of the hollow cylinder  312 , and the axially mobile vacuum plunger closes tightly against the internal walls of the hollow cylinder  312 . The upper side of the hollow cylinder  312  is closed through a cover plate  316 . A pressure-tight feed-through for a rod  314  is provided in the cover plate  316 , whereby the rod  314  is connected to the vacuum plunger  347  such that the vacuum plunger  347  can be moved in the hollow space  346  by pushing in the rod  314 . Another feed-through is provided as connector  352  for a vacuum conduit  317 . The vacuum conduit  317  connects the intervening space  349  and/or the hollow space  349  between the vacuum plunger  347  and the cover plate  316  to the internal space  324  of the cartridge  301 . For this purpose, the vacuum conduit  317  is connected to a feed-through in the dispensing plunger  302 . A pore disc  328  is provided in the feed-through and/or in the dispensing plunger  302 . 
         [0181]    Unlike the previous exemplary embodiments, the vacuum plunger  347  and the pumping plunger  344  are not directly connected to each other in the present device. Instead, a shared component  315  is provided by means of which the rod  314 , and thus the vacuum plunger  347 , and the pumping plunger  344  can be pushed downward (downward in  FIG. 9 ). 
         [0182]    A connecting conduit  238  connected via a junction  354  is connected, on the bottom, to a connector  320  for a monomer container  360 . The present monomer container  360  is a metal-coated film pouch  360  that can be slit open on the inside of the connector  320  using mandrels  364  or blades. For this purpose, a lid  322  (for example a screw lid) of the monomer container  360  can be pushed onto the mandrels  364 . The floor  358  of the connector  320  is inclined to allow the monomer liquid to readily flow out of the connector  320 . Ventilation feed-throughs (not shown) can be provided in the lid  322  to allow air to flow in when the monomer liquid flows out into the connector  320 . A screen  356  is provided in the connector  320  to be able to retain scraps or particles of the slit or punctured monomer container  360 . 
         [0183]    The monomer liquid flows from the monomer container  360  through the connecting conduit  338  into the hollow space  341 . The liquid level of the monomer liquid cannot rise above the loop  314 , since the same is arranged at a higher place than the junction  354 . The operating element  315  is used to exert a pressure onto the pumping plunger  344 . The pumping plunger  344  is used to push the monomer liquid out of the hollow space  341  into the internal space  324  of the cartridge  301 . Concurrently, the operating element  315  pushes the vacuum plunger  347  downwards by means of the rod  314 . In this process, the hollow space  349  is being enlarged and air is thus drawn from the internal space  324  of the cartridge  301  via the vacuum conduit  317  into the hollow space  349 . The monomer liquid can be mixed with the cement powder in the internal space  324  of the cartridge  301  using the mixing facility  326 . Subsequently, the cartridge  301  is separated from the connecting conduit  338  and the vacuum conduit  317 . The passage through the dispensing plunger  302  can be closed for this purpose. The dispensing plunger  302  can be used to expel the ready-made mixture through the opening in the floor of the cartridge  301  from which the filter  332  has been removed. In this context, a dispensing tube (not shown) can be attached to the opening in the floor of the cartridge  301  (on the bottom in  FIG. 9 ) 
         [0184]    The features of the invention disclosed in the preceding description and in the claims, figures, and exemplary embodiments, can be essential for the implementation of the various embodiments of the invention both alone and in any combination. 
       LIST OF REFERENCE NUMBERS 
       [0000]    
       
           1 ,  101 ,  201 ,  301  Cartridge 
           2 ,  102 ,  202 ,  302  Dispensing plunger 
           4 ,  104 ,  204 ,  304  Mixing rod 
           6 ,  106 ,  206  Handle part 
           8 ,  108 ,  208  Socket 
           10 ,  110 ,  210  Base 
           12 ,  112 ,  212 ,  312  Hollow cylinder for the vacuum plunger 
           14 ,  114 ,  214 ,  314  Rod 
           15  Push-button 
           16 ,  116 ,  216 ,  316  Cover plate 
           17 ,  117 ,  217 ,  317  Vacuum conduit 
           18 ,  118 ,  218  Connector socket 
           20 ,  120 ,  220 ,  320  Connector for the monomer container 
           21 ,  121 ,  221  Elastic receptacle for the monomer container/opening means 
           22 ,  122 ,  222 ,  322  Lid 
           24 ,  124 ,  224 ,  324  Internal space of the cartridge 
           26 ,  126 ,  226 ,  326  Mixing vane/mixing facility 
           28 ,  128 ,  228  Sterilisation plunger 
           29 ,  129 ,  229  Seal 
           30 ,  130 ,  230  Sealing plunger 
           32 ,  132 ,  232 ,  332  Powder-impermeable and liquid-permeable filter 
           34 ,  134 ,  234  Base connector with external thread 
           36 ,  136 ,  236  Cartridge connector with internal thread 
           38 ,  138 ,  238 ,  338  Connecting conduit 
           40 ,  140 ,  240 ,  340  Loop of the connecting conduit 
           41 ,  141 ,  241 ,  341  Hollow space for the pumping plunger 
           42 ,  142 ,  242 ,  342  Hollow cylinder for the pumping plunger 
           43 ,  143 ,  243 ,  343  Bottom of the hollow cylinder for the pumping plunger 
           44 ,  144 ,  244 ,  344  Pumping plunger 
           45 ,  145 ,  245 ,  345  Lower surface of the pumping plunger 
           46 ,  146 ,  246 ,  346  Open (lower) hollow space for the vacuum plunger 
           47 ,  147 ,  247 ,  347  Vacuum plunger 
           48 ,  148 ,  248  Seal 
           49 ,  149 ,  249 ,  349  Closed (upper) hollow space for the vacuum plunger 
           50 ,  150 ,  250  Opening 
           52 ,  152 ,  252 ,  352  Connector for the vacuum conduit 
           53 ,  153 ,  253  Seal 
           54 ,  154 ,  254 ,  354  Junction into the hollow cylinder for the pumping plunger 
           56 ,  156 ,  256 ,  356  Screen/filter 
           58 ,  158 ,  258 ,  358  Inclined floor surface of the connector for the monomer container 
           60 ,  160 ,  260  Glass ampoule/monomer container 
           62 ,  162 ,  262  Head of the glass ampoule/head of the monomer container 
           115  Securing facility 
           151  Tensioned compression spring 
           215  Hood 
           223  Ventilation passage 
           239  Housing for loop of the connecting conduit 
           315  Shared operating element 
           328  Closable pore filter 
           360  Monomer pouch/monomer container 
           364  Mandrel