Apparatus, use, and system for extruding bone cement

Abstract

To provide an apparatus for pressing out bone cement from a cartridge, a use of the apparatus, and a system for pressing out bone cement.SOLUTION: An apparatus (10) for pressing out bone cement from a cartridge comprises a threaded rod (20) with an external thread (22), a handle (24) for rotating the threaded rod (20), and an adapter unit for mechanically connecting to a cartridge for bone cement. The adapter unit (26) has a passage (27) with an internal thread (28) for the threaded rod (20). An outer surface of a thread turn of the external thread (22) is 370 mm2 or less. This particularly facilitates pressing out highly viscous bone cement.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an apparatus for extruding bone cement from a cartridge, the use of the apparatus, and a system for extruding bone cement. [Overview of the project] [Problems that the invention aims to solve]

[0002] Bone cement is typically manufactured by mixing a powder with a liquid. For example, polymethyl methacrylate (PMMA) bone cement, composed of a liquid monomer component and a powder component, is known. The monomer component generally contains monomer methyl methacrylate and, in particular, an activator dissolved therein, such as N,N-dimethyl-p-toluidine. The powder component, also called bone cement powder, comprises methyl methacrylate and one or more polymers produced by polymerization, preferably suspension polymerization, based on comonomers such as styrene, methyl acrylate, or similar monomers, and, in particular, a radiopaque agent and / or a dibenzoyl peroxide initiator. When the powder component is mixed with the monomer component, for example, the polymer of the powder component expanding in the methyl methacrylate produces a plastically deformable paste, the actual bone cement (also called bone cement paste). When the powder component is mixed with the monomer component, the activator, such as N,N-dimethyl-p-toluidine, reacts with dibenzoyl peroxide to form a radical. The formed radical can initiate the radical polymerization of methyl methacrylate. As the polymerization of methyl methacrylate progresses, the viscosity of the cement can continue to increase until the cement hardens.

[0003] PMMA bone cement is primarily used to permanently fix intra-articular prostheses to bone. Generally, 50g to 125g or more of cement is used to fix intra-articular prostheses. Bone cement is needed during the patient's surgery and should be provided quickly. This is the main application area of ​​this invention.

[0004] Polymethyl methacrylate bone cement can be mixed by mixing the cement powder with the monomer liquid using a spatula in a suitable mixing beaker. During the process, air bubbles may be incorporated into the bone cement, which can adversely affect the mechanical properties of the hardened bone cement. Other drawbacks include the need for manual measurement of quantities and the fact that proper mixing is not always guaranteed.

[0005] Vacuum cementing systems are known for preventing air from being incorporated into bone cement. Examples include US6033105A, US5624184A, US4671263A, US4973168A, US5100241A, WO99 / 67015A1, EP1020167A2, US5586821A, EP1016452A2, DE3640279A1, WO94 / 26403A1, EP1005901A2, EP1886647A1, and US5344232A. Further advancements in cementing technology are represented by cementing systems, in which both cement powder and monomer liquid are already packaged in separate compartments and mixed together immediately before cement application in the cementing system. Such sealed, fully pre-packaged mixing systems or similar systems are described, in particular, in the documents EP0380867B1, EP0796653B1, EP0692229A1, DE102009031178B3, US5997544A, US6709149B1, WO00 / 35506A1 and EP0796653A2.

[0006] Mixing apparatuses that use an external device for extruding bone cement are disclosed in WO9416951A1, EP1741413B1, EP3054880B1, and DE19718648A1. Mixing apparatuses or similar systems that apply vacuum to enable the transfer or mixing of components or bone cement are known from US8662736B2 and EP3093067B1. EP2393456B1 describes a mixing apparatus in which a liquid is injected into a powder by an overpressure means.

[0007] Manually operated discharge devices are based on, for example, a hand-operated lever system connected to a cement cartridge that drives a push rod or toothed bar. By repeatedly tilting the lever, the push rod or toothed bar is moved toward the discharge piston of the cartridge, and the discharge piston moves toward the cartridge head, thereby pushing the polymethyl methacrylate bone cement out of the cartridge through a discharge pipe mounted on its front. Such or similar discharge devices are disclosed in US589344A, US5638997A, and WO9416951A.

[0008] Screw systems are generally used to extract small amounts of bone cement, up to approximately 10 g, and to stabilize fractured vertebral bodies. To date, these known screw systems have low mechanical load-bearing capacity and are unsuitable for extracting larger amounts of PMMA bone cement, at least 50 g. Examples of such extraction devices or similar devices are published in US6676663B2, US2012224452A1, CN218220290U, and CN213190021U.

[0009] The objective of the present invention is to enable particularly simple manual discharge of large quantities of bone cement. In particular, to create a particularly simple and cost-effective apparatus that overcomes at least some of the shortcomings of the prior art.

[0010] This objective is achieved by the apparatus for mixing bone cement described in claim 1, and by the use and system described in the independent claim. Advantageous embodiments are provided in the dependent claims.

[0011] This objective is achieved by a device for extruding bone cement. This device comprises a threaded rod having male threads, a handle for rotating the threaded rod, and an adapter unit for mechanically connecting to a cartridge for bone cement. The adapter unit has a passage with female threads for the threaded rod. In one embodiment, the outer surface of the threads of the male thread is at most 370 mm. 2 That is the case.

[0012] The outer surface has been shown to strongly influence frictional losses when the threaded rod rotates within the adapter unit, and thus the force required to expel bone cement. The outer surface is a measure of the surface area of ​​the male threads in contact with the female threads. Therefore, the resulting friction is proportional to the outer surface. Tests have shown that the reduction in outer surface is independent of whether it is achieved by reducing thread depth, increasing flank angle, reducing the diameter of the threaded rod, reducing pitch, or other measures, or by a combination of different measures. Only the absolute value of the outer surface matters.

[0013] Bone cement is typically highly viscous. Therefore, a particularly large force is often required to extrude it. For example, extruding 130g of high-viscosity PMMA bone cement from a cement cartridge may require a driving force of up to 2kN, which is equivalent to a weight of almost 200kg. Therefore, it is necessary to reduce friction so that bone cement can be extruded with less manual force. This allows even those with less strength to easily operate the device. This is especially important because the bone cement continues to harden over time after mixing, and therefore the force required to extrude it increases over time. Tests have shown that the aforementioned maximum outer surface area of ​​the male screw threads allows any user to easily discharge the bone cement by manually rotating the handle. A larger outer surface area would make discharge extremely difficult due to static and sliding friction, making it cumbersome to handle.

[0014] The device can be made of a plastic material or a plastic material containing metal. It does not require a complex mechanism as seen in a cement gun. Levers, bolts, pins, clamps, locking elements, toothed bars and / or gears are not necessary. The force required to extrude the bone cement is smaller than the force required by conventional devices such as cement guns.

[0015] The device according to the present invention is easy to handle because it does not require complex operation of the gun. Discharge is performed simply by rotating the handle.

[0016] A thread turn means the helix of the thread over a distance corresponding to a complete relative rotation of 360°, i.e., one rotation is considered. The outer surface is the area of the male thread that can contact the corresponding female thread. The outer surface of the thread turn is, for example, the surface of the first (e.g., rising) thread flank, the surface of the second (e.g., falling) thread flank, a surface in the region of the thread peak that may extend parallel to the longitudinal axis and / or may be located between the thread flanks, and a further surface in the region of the thread recess or valley that may be located between the two thread flanks. These four surfaces are added over one rotation. In other words, the surface area between two adjacent peaks or valleys of the thread is considered. The rounding or transition between the individual surfaces is also part of the outer surface. Each characteristic value of the male thread of the threaded rod can be correspondingly applied to the female thread of the adapter unit.

[0017] For example, in the case of a trapezoidal thread, the outer surface corresponds to the surfaces of the two thread flanks, the outward surface between them in the region of the thread peak that defines the outer diameter of the male thread, and the outward surface in the region of the thread valley that defines the inner diameter of the male thread.

[0018] In the case of a multi-start thread, the surface areas of all thread turns are added over one rotation.

[0019] The threaded rod is designed to be rotated by manual rotation of the handle. In particular, for this purpose, the handle is connected to the threaded rod for coupled rotation. The female thread interacts with the male thread of the threaded rod so that the threaded rod can rotate relative to the female thread. The female thread and the male thread correspond. Due to the interaction between the threaded rod and the adapter unit, the rotation of the threaded rod causes an axial translational relative movement between the threaded rod and the adapter unit. The extending direction of the threaded rod defines the axial direction of the device. Preferably, the threaded rod is guided through a passage so that the female thread engages with the male thread. However, the threaded rod and the adapter unit may also be available separately, so that the user has to first screw the threaded rod into the adapter unit before using it as intended.

[0020] The adapter unit is designed to be mechanically attached to a cartridge that houses bone cement. In particular, at least a connection for coupled rotation is provided in the rotational direction of the threaded rod so that the attachment of the adapter unit to the cartridge is not impaired or loosened when the threaded rod is rotated. Typically, the adapter unit includes one or more first clamping means, the cartridge includes one or more second clamping means, and the two clamping means interact and are adapted to establish a mechanical clamping. For example, the cartridge may have a male thread and the adapter unit may have a corresponding female thread. The passage of the adapter unit is particularly centrally located.

[0021] When the adapter unit is attached to the cartridge, the end of the threaded rod far from the handle penetrates into the cartridge by the axial relative movement of the threaded rod relative to the adapter unit, and thus to the cartridge, and thus extrudes the bone cement from the cartridge. In this way, the bone cement can be extruded from the end of the cartridge on the opposite side of the adapter unit.

[0022] In particular, the device includes a pressure element at the end of a threaded rod, far from the handle, for applying pressure to the bone cement in the cartridge. This pressure can be applied directly or indirectly. For example, the pressure element can directly press the bone cement, or it can press another element, such as a piston in the cartridge, which then presses the bone cement.

[0023] In one embodiment, the outer surface of the thread turn of the male screw thread is at least 230 mm 2 That is the case.

[0024] The lower limit of the outer surface ensures that the mechanical stability of the threaded rod is maintained. For example, if the outer surface is too small, the thread depth or the diameter of the threaded rod may be too small, potentially leading to shearing of the male threads and / or twisting or buckling of the threaded rod.

[0025] The pitch of the male screw threads also affects the force required for discharge. The pitch of the male screw threads is the distance covered in one rotation, measured axially. Generally, if the pitch is too short, the rotation ratio becomes very high, and therefore more rotations are required to discharge the bone cement, thus increasing the effort required during use. This is undesirable, as it can result in too much time being needed, especially during surgery and / or when the bone cement is gradually hardening. Generally, if the pitch is too long, the rotation ratio becomes low, and therefore the force required to discharge the bone cement becomes very high. In addition, if the pitch is too steep, the self-locking function may be reduced or eliminated, which then unnecessarily complicates the operation. The specific numerical values ​​of these effects depend on different conditions such as the material used and the properties of each surface.

[0026] In one embodiment, the pitch of the male thread is at least 1 mm and / or at most 7 mm. This has proven particularly effective in testing. In particular, the pitch is at least 2 mm, preferably at least 3 mm, especially preferably at least 4 mm, and / or at most 5 mm, preferably at most 5 mm. In one embodiment, the pitch is approximately or exactly 4.5 mm.

[0027] In one embodiment, the outer diameter of the male thread of the threaded rod is at least 12 mm and / or at most 17 mm. The outer diameter refers to the maximum diameter measured between the two maximum peaks of the thread, i.e., the diameter of the virtual circular cylinder surrounding the male thread.

[0028] In particular, the outer diameter is at least 13.5 mm and / or at most 15 mm. In one embodiment, the outer diameter is approximately or exactly 14 mm. An outer diameter of less than 12 mm is not suitable for withstanding the generated forces or moments. If the outer diameter is too large, friction increases, and therefore the force required for discharge increases.

[0029] In one embodiment, the female thread of the adapter unit includes at least two and / or as many as seven thread turns. This means that the aforementioned number of turns is required to fully screw the threaded rod into the female thread. Generally, too few threads in the adapter unit result in low holding force, low strength, and / or high load on each thread turn. Generally, too many thread turns increase friction and therefore require a greater force to expel the bone cement. The numbers mentioned have proven to be particularly useful.

[0030] In particular, the female threads include at least three thread turns, preferably at least or exactly four thread turns, and / or at most six thread turns, preferably at most five thread turns. This has been proven to be the optimal condition for the effects described above.

[0031] In one embodiment, the threads of the threaded rod are trapezoidal. This has proven to be particularly suitable.

[0032] In one embodiment, the male threads of the threaded rod have a thread depth of at least 1 mm and / or a maximum of 4 mm. In principle, if the thread depth is too shallow, the strength of the threads decreases and / or mechanical stress increases. Generally, if the thread depth is too deep, friction increases, and therefore the force required to expel bone cement increases. The values ​​mentioned have proven to be particularly useful.

[0033] In particular, the thread depth is 2 mm or less, and / or approximately or exactly 1.5 mm. This has proven to be optimal in terms of the effects mentioned.

[0034] In one embodiment, to apply pressure to the bone cement in the cartridge, the device has a pressure element at the end of a threaded rod, far from the handle. In particular, the pressure element has a flat surface.

[0035] As described above, pressure elements can be designed to apply pressure directly or indirectly. For example, a pressure element can be designed as a plate. In one embodiment, the pressure element is connected to a threaded rod for coupling rotation. For example, the pressure element can be screwed onto the threaded rod, welded to it, or connected to the threaded rod by a plug connection.

[0036] The pressure element can be made entirely or partially from metal or plastic materials, such as glass fiber reinforced plastics and / or polyamides.

[0037] In one embodiment, the pressure element consists of two parts. The first part of the pressure element is connected to a threaded rod for coupling rotation. The second part of the pressure element is connected to the first part so as to rotate about the longitudinal axis of the threaded rod.

[0038] The second part is used to apply pressure to bone cement or a portion of the cartridge. The first part connects the second part to a threaded rod and / or transmits the compressive force of the threaded rod to the second part. To ensure particularly smooth relative rotation between the first and second parts, a lubricant such as silicone may be provided between the first part of the pressure element. In one embodiment, the second part surrounds the first part at least partially or circumferentially. In other words, the second part engages behind the first part. This ensures that the first and second parts do not separate from each other. This prevents axial movement of the second part away from the first part, and thus prevents loss of the second part.

[0039] In particular, the surface of the second part facing the first part and / or the surface of the first part facing the second part are flat and / or smooth. This allows for particularly smooth relative rotation. In particular, the surface of the second part facing the first part and / or the surface facing the second part are made of metal.

[0040] In one embodiment, the adapter unit has a recess. In particular, the recess is axially positioned between a connecting element or connecting area of ​​the adapter unit for mechanically connecting to a cartridge of the adapter unit and / or a female thread or passage. The recess is designed to accommodate at least substantially a pressure element.

[0041] In particular, the recess is circular in shape and / or centrally located when viewed along the longitudinal axis of the threaded rod. Specifically, the recess is circular-cylindrical in shape. The recess serves to accommodate the pressure element. This means that the pressure element does not protrude beyond the recess or significantly in the direction of the connecting element. This ensures that, for example, the connection area of ​​the cartridge remains clear into which the adapter unit can be inserted. The recess may have an axial extension of, for example, at least 3 mm, preferably 4 mm, and / or at most 10 mm, particularly at most 7 mm, preferably at most 5 mm. The axial extension of the recess may correspond approximately or exactly to the axial extension of the pressure element. The pressure element can be completely housed within the recess.

[0042] In one embodiment, the threaded rod comprises an inner rod, for example, a metal rod, and / or a casing, for example, a plastic casing.

[0043] The internal rod provides a mechanically stable threaded rod. In particular, the rod is not rotationally symmetrical. This ensures a secure connection between the rod material, e.g., metal, and the casing material, e.g., plastic. For example, the rod can be hexagonal or square. Metal rods made from or having stainless steel such as 316L are particularly used.

[0044] In particular, the rod is completely covered with plastic material. Specifically, the threads are made of plastic material. This provides particularly smooth threads. The rod is protected from external influences.

[0045] In one embodiment, the metal rod has a diameter of at least 7 mm and / or at most 10 mm, preferably about or exactly 8 mm. If the diameter is too small, it may lead to twisting and / or buckling of the threaded rod under full load. If the diameter is too large, the diameter of the threaded rod increases, and thus friction increases.

[0046] In one embodiment, the adapter unit is designed to connect to the cartridge by a bayonet connection. In particular, the direction of rotation of the adapter unit for connecting it to the cartridge corresponds to the direction of rotation for screwing the threaded rod into the adapter unit.

[0047] Therefore, the adapter unit is equipped with a connecting element for forming a bayonet connection with the cartridge. The cartridge is specifically equipped with a corresponding connecting element. This allows for a simple and secure connection. This also enables interaction with existing cartridges.

[0048] The direction of rotation for screwing the threaded rod into the adapter unit is the direction in which the handle, and thus the threaded rod, is rotated to push the bone cement out of the cartridge. During this rotation, the connection is pushed toward the connection position. This prevents the connection from loosening or becoming loose due to the rotation.

[0049] In one embodiment, the threaded rod has a length of at least 15 cm and / or a maximum of 23 cm. In one embodiment, the adapter unit has a connection area for insertion into a cartridge. In one embodiment, the connection area has an inner diameter of at least 3.3 cm and / or a maximum of 4.0 cm.

[0050] The length of the threaded rod is, in particular, at least 15 cm, preferably at least 17 cm, especially preferably at least 19 cm, and / or at most 25 cm, preferably at most 23 cm, especially preferably at most 21 cm or 20 cm. This length is particularly suitable for quickly and with reasonable effort discharging a desired amount, for example, at least 50 g and / or at most 130 g of bone cement.

[0051] The connection area can be inserted onto one end of the cartridge. In the case of a screw or bayonet connection, this can be achieved, for example, by screwing in or unscrewing. The connection area can have an inner diameter of at least 3 cm, preferably at least 3.3 cm, particularly at least 3.5 cm, and / or at most 4.0 cm, particularly at most 3.8 cm. The inner diameter of the connection area substantially corresponds to the outer diameter of the cartridge. Such diameters have been shown to be particularly suitable for discharging a desired amount, e.g., at least 50 g and / or at most 130 g of bone cement, quickly and with reasonable effort.

[0052] In one embodiment, at least a portion of the adapter unit, handle, and / or threaded rod is made of a plastic material. In particular, the plastic material is polyamide, polyketone, polysulfone, and / or polyoxymethylene. The plastic material is preferably polyamide 6, polyamide 6,6, and / or polyamide 12. These plastic materials have proven to be optimal in terms of strength, durability, and cost.

[0053] A further embodiment is the use of the apparatus described in any one of the preceding claims for extruding at least 50 g and / or more than 130 g of bone cement from a cartridge. All the features, advantages and configurations of the apparatus described above also apply to the use and vice versa.

[0054] In particular, PMMA bone cement is extruded. This is done specifically to fix intra-articular prostheses to human bone tissue. Specifically, the cartridge is a cementing system cartridge for fixing intra-articular prostheses to human bone tissue.

[0055] A further aspect of the present invention is a system for extruding bone cement, comprising a cartridge and apparatus for bone cement according to the present invention for extruding bone cement. In particular, the cartridge contains bone cement or at least components for the production of bone cement. All the features, advantages and embodiments of the apparatus and use described above also apply to the system, and vice versa.

[0056] In particular, the cartridge has a connection area that interacts with the connection area of ​​the device so that a mechanical connection can be established between the adapter unit and the cartridge.

[0057] The cartridge can be connected to one or more suitable hoses and / or one or more suitable tubes at the end facing away from the adapter unit to transport bone cement to the desired location. It is also possible to fill one or more spacer molds with bone cement.

[0058] A further aspect of the present invention is a method for extruding bone cement from a cartridge, wherein the handle of the apparatus according to the present invention is manually rotated so that the bone cement is extruded from the cartridge. All the features, advantages and embodiments of the apparatus, use and system described above also apply to the method and vice versa.

[0059] Exemplary embodiments of the present invention are also described in more detail below with reference to the drawings. Features of the exemplary embodiments can be combined with individual or multiple claimed subject matter unless otherwise specified. The scope of claimed protection is not limited to the exemplary embodiments. [Brief explanation of the drawing]

[0060] In the drawing, [Figure 1] Figure 1 is a perspective view of a device comprising an alternative embodiment of the adapter unit according to the present invention. [Figure 2] Figure 2 is a cross-sectional view of the apparatus according to the present invention. [Figure 3]Figure 3 is a further cross-sectional view of the apparatus according to the present invention. [Figure 4] Figure 4 is a further cross-sectional view of the apparatus according to the present invention. [Figure 5] Figure 5 is a cross-sectional view showing the use of the apparatus according to the present invention. [Figure 6] Figure 6 is a further cross-sectional view of the use of the apparatus according to the present invention. [Figure 7] Figure 7 is a detailed enlarged view of a threaded rod.

[0061] Figure 1 shows a device 10 for extruding bone cement from a cartridge according to the present invention. The device 10 comprises an adapter unit 26 having a connection area 37 for mechanically connecting to a cartridge. In the embodiments shown herein, the connection area 37 may be inserted into or screwed into a corresponding area of ​​the cartridge, as shown in Figures 5 and 6. In the embodiments shown herein, the adapter unit 26 has a connection element 29 for forming a bayonet connection. The rotational direction for tightening the bayonet connection corresponds to the rotational direction for screwing into a threaded rod 20.

[0062] The device further comprises a threaded rod 20 having male threads 22. The threaded rod 20 is passed through the passage 27 such that the male threads 22 engage with female threads located within the passage 27. A manual operating handle 24 for rotation is located at the end of the threaded rod 20 shown on the right side. When the threaded rod 20 is rotated, the threaded rod moves axially through the adapter unit 26 so that it can extrude bone cement.

[0063] At the end of the threaded rod 20 furthest from the handle 24, the threaded rod 20 is designed to apply pressure or force to the bone cement. For this purpose, a pressure element, such as the pressure element 30 shown in Figure 2, may be present.

[0064] An alternative adapter unit 26 is shown by a dashed circle. This is basically designed similarly to the adapter unit 26 described above, shown below, but additionally includes a grip 50. This can have the form of radially protruding spikes. The grip 50 acts as a counter bearing during manual rotation of the handle 24. The user can rotate the handle 24 with one hand and simultaneously hold the adapter unit 26 or the cartridge connected to the adapter unit 26 firmly at the grip 50 with the other hand. This allows for a lower holding force and therefore easier rotation. Discharge of bone cement is further simplified.

[0065] Figure 2 shows a cross-sectional view of the threaded rod 20 along its central longitudinal axis, illustrating an embodiment of the apparatus 10 similar to that in Figure 1. To avoid repetition, only the differences from Figure 1 will be described.

[0066] It can be seen that a pressure element 30 is located at the end of the threaded rod 20, far from the handle 24. The pressure element 30 plays a role in applying pressure to the bone cement, either directly or indirectly, to push it out of the cartridge. For example, the pressure element 30 can move the piston of the cartridge, which then pushes the bone cement out of the cartridge.

[0067] The pressure element 30 consists of two parts. The first part 31 is firmly connected to the threaded rod 20, so that it rotates with the threaded rod 20 when the rod rotates. The second part 32 is rotatably connected to the first part 31 so that the second part 32 does not rotate when the threaded rod 20 rotates. In this way, no rotational motion is applied to the bone cement 15 and / or piston, and only axial pressure is applied. The contact surfaces of the first part 31 and the second part 32 are preferably flat and smooth to allow for smooth rotation.

[0068] It can also be seen that the threaded rod 20 has an inner core, which is a metal rod 40 in the example shown herein, and a casing, which is a plastic casing 41 in the example shown herein. The metal rod 40 extends to the center of the threaded rod 20 and significantly contributes to the mechanical stability of the threaded rod 20. The plastic casing 41 forms male threads 22 and protects the metal rod 40 from external influences. The metal rod 40 is preferably not rotationally symmetric to ensure connection to the handle 24 for coupling rotation.

[0069] Figure 2 also shows the female thread 28 in the passage 27 of the adapter unit 26. The female thread contains four or five thread turns. Both the male thread 22 and the female thread 28 have a pitch of 3 mm to 6 mm.

[0070] Figures 3 and 4 show an embodiment of the apparatus 10 similar to that in Figure 2, as a cross-sectional view along the longitudinal central axis. Again, to avoid repetition, only additional features are described. In Figure 3, as in Figures 1 and 2, the threaded rod 20 is shown in the fully unscrewed position from the adapter unit 26. In contrast, Figure 4 shows the threaded rod 20 already partially rotated through the adapter unit 26, as seen when bone cement is being extruded.

[0071] As shown in Figure 3, the adapter unit 26 is shown to have a recess 35 that can completely accommodate the pressure element 30. In this way, the connection area 37 of the adapter unit 26 shown on the left side is free of the pressure element 30. Thus, the connection area 37 can slide onto, insert into, or screw onto the corresponding end of the cartridge without interfering with the pressure element 30.

[0072] Figure 3 also shows some of the dimensions of the device 10. The threaded rod 20 has a length L of 18 cm to 20 cm. The length L is measured between the outermost regions where the male threads 22 are located. The connection region 37 of the adapter unit 26 has a diameter D of 34 mm to 40 mm. The diameter of the connection region 37 approximately corresponds to the outer diameter of the corresponding connection region of the cartridge to be connected.

[0073] It can be seen that the second portion 32 of the pressure element 30 surrounds the first portion 31 of the pressure element 30 and / or forms an engagement portion 34 with it. On the right side, the second portion 32, in particular the circumferential outer rim, extends inward and engages behind the radially outer edge of the first portion 31.

[0074] The first portion 31 and / or the second portion 32 can be designed in the form of a plate. The second portion 32 may have a diameter of at least 20 mm and / or at most 30 mm, for example, approximately or exactly 25 mm.

[0075] Furthermore, the outer diameter D of the threaded rod 20 is measured radially between the peaks of the male thread 22. A This is shown. The outer diameter D in the example shown here A The size is 13.5mm to 15mm.

[0076] Figures 5 and 6 show the use of the device 10 according to the invention with different cartridges 12. The connection area 37 of the adapter unit 26 is slid onto one end of the cartridge 12 and mechanically clamped thereto, as described. The cartridge 12 has a discharge opening at the opposite end, and a tube 51 for discharging, for example, bone cement 15 is connected to the discharge opening. There is bone cement 15 inside the cartridge. Typically, the cartridge 12 also includes a piston 13 that is at least substantially sealed against the inner wall of the cartridge 12. The pressure element 30 of the device 10 is designed to apply axial pressure to this piston 13, for example, to push the bone cement 15 out of the cartridge. Figure 5 shows the first pressing process in which the pressure element 30 and the piston 13 are pushed to the left until the bone cement 15 is flat against the piston 13. Figure 6 shows a more advanced pressing process in which the bone cement 15 is carried out through the tube 51 by the continuous rotation of the handle 24.

[0077] Figure 7 is an enlarged cross-sectional view of the threaded rod 20. It includes an internal metal rod 40 and a plastic casing 41 that completely encloses the metal rod 40. The outer diameter D of the threaded rod 20 corresponding to the maximum diameter between the peaks on both sides of the male thread 22 is shown. A In addition, the inner diameter D of the threaded rod 20 corresponding to the minimum diameter between the depressions or valleys on both sides of the male thread 22 is shown. I The thread has a thread depth of 1 mm to 2 mm. Thus, the difference between the inner diameter D I and the outer diameter D A is 2 mm to 4 mm.

[0078] The thread turn 66 is delimited by a dashed line as an example. The thread turn corresponds to a complete one rotation of the male thread 22 with respect to the corresponding female thread. The threaded rod 20 has an outer surface of the thread turn 66 of the male thread 22 that is at most 3 seventieths of a millimeter 2It can be designed to be such. In the example of the trapezoidal screw shown here, the outer surface of the thread is determined as the sum of the upper surface 61 corresponding to the surface of the peak region of the thread, the lower surface 62 corresponding to the surface of the recess region of the thread, the first (rising) flank surface 63, and the second (descending) flank surface 64.

[0079] In one embodiment, the outer surface of the thread turn of the male screw thread is at most 450 mm 2 , especially at a maximum of 430mm 2 Preferably a maximum of 400 mm 2 Particularly preferably a maximum of 370 mm 2 In one embodiment, the outer surface of the thread turn of the male screw thread is at most 350 mm. 2 , especially at a maximum of 330mm 2 Preferably a maximum of 300 mm 2 In one embodiment, the outer surface of the thread turn of the male screw thread is at least 100 mm 2 Typically, at least 130 mm 2 , especially at least 160mm 2 Preferably at least 180 mm 2 , especially preferably at least 200 mm 2 More preferably, at least 215 mm 2 In one embodiment, the outer surface of the thread turn of the male thread is at least 250 mm 2 Typically at least 280 mm 2 , especially at least 320mm 2 Preferably at least 350 mm 2 These values ​​may be particularly appropriate depending on the design and materials.

[0080] Example 1: Thread pitch 4.5 mm, outer diameter of male thread D AA device with a diameter of 14 mm and a thread depth of 1.5 mm was fabricated. This has proven to be ideal for rapidly extruding up to 130 g of high-viscosity bone cement from a cement cartridge with minimal effort. Complete extrusion of 130 g of bone cement from the applicant's commercially available PALAMIX® cement cartridge could be achieved in under 1.5 minutes. Similar results were achieved with the applicant's sealed cementing system PALACOS PRO® (2021 version).

[0081] Example 2: The adapter unit 26, threaded rods 20 having diameters of 30 mm, 25 mm, 20 mm, and 14 mm and pitches of 4.5 mm and 7.0 mm, and a matching handle were manufactured from polyamide 12 using selective laser sintering (SLS). In particular, some or all of the components were subsequently chemically smoothed. The threaded rods 20 contain a hexagonal rod made of standard stainless steel internally. In particular, this was press-fitted into the plastic part after manufacturing.

[0082] For the extrusion test, the applicant's commercially available mixed system PALAMIX and polymethyl methacrylate bone cement PALACOSR+G, as well as commercially available vancomycin hydrochloride, were used.

[0083] An extrusion test was conducted using approximately 118 g of bone cement obtained from two packs of PALACOSR+G (2 × 40.8 g cement powder + 2 × 18.5 g monomer liquid) mixed in a PALAMIX cartridge. Subsequently, the bone cement was extruded using the manufactured apparatus, and the ease of use of each apparatus was evaluated. The results are shown in Table 5 below.

[0084] [Table 1]

[0085] Furthermore, similar experiments were conducted using two packs of PALACOSR+G and two monomer ampoules, each containing 18.5g of monomer solution, to which 4.0g of vancomycin hydrochloride was added. The theoretical amount of cement was approximately 126g of cement paste. Similar results were obtained to those of the initial series of experiments.

[0086] Reference Code List 10 equipment 12 cartridges 13 pistons 15 Bone cement 20 Threaded Rods 22 Male screw thread 24 handles 26 Adapter Units 27 aisle 28 Female threads 29 Connection Elements 30 Pressure elements 31 Part 1 32 Part 2 33 Surface 34 Engagement 35 recess 37 Connection Area 40 metal rods 41 Plastic casing 50 Grips 51 Tubes 61 Top surface 62 Bottom surface 63 First Frank Face 64. The second Frank face 66 thread turn D Inner diameter D I Inner diameter D A Outer diameter L Length

Claims

1. A device (10) for extruding bone cement (15) from a cartridge (12), comprising a threaded rod (20) having male threads (22), a handle (24) for rotating the threaded rod (20), and an adapter unit (26) for mechanically connecting to a cartridge (12) for bone cement (15), wherein the adapter unit (26) has a passage (27) having female threads (28) for the threaded rod (20), The outer surface of the thread turn (66) of the male thread (22) is 230 mm to 370 mm. ２ And, The device (10) is provided with a pressure element (30) having a flat surface (33) at the end of the threaded rod (20) furthest from the handle (24) for directly or indirectly applying pressure to the bone cement (15) located within the cartridge (12), The apparatus is characterized in that the pressure element (30) is composed of two parts, the first part (31) of the pressure element (30) is connected to the threaded rod (20) so as to rotate integrally, and the second part (32) of the pressure element (30) is connected to the first part so as to rotate about the longitudinal axis of the threaded rod (20).

2. The apparatus (10) according to claim 1, characterized in that the pitch of the male thread (22) is at least 1 mm and / or at most 7 mm.

3. The apparatus (10) according to claim 1, characterized in that the outer diameter (DA) of the male thread (22) of the threaded rod (20) is at least 12 mm and / or at most 17 mm.

4. The apparatus (10) according to claim 1, characterized in that the female thread (28) of the adapter unit (26) includes at least two and / or at most seven thread turns.

5. The apparatus (10) according to claim 1, characterized in that the male thread (22) of the threaded rod (20) has a thread depth of at least 1 mm and / or a maximum of 4 mm.

6. The apparatus (10) according to claim 1, characterized in that the adapter unit (26) has a recess (35), the recess (35) is axially positioned between a connection area (37) or connection element (29) of the adapter unit (26) for mechanically connecting to the cartridge (12) and the female thread (28), and the recess (35) is adapted to accommodate at least substantially the pressure element (30).

7. The apparatus (10) according to claim 1, characterized in that the threaded rod (20) comprises an inner metal rod (40) and a plastic casing (41).

8. The apparatus (10) according to claim 1, wherein the adapter unit (26) is designed to be connected to the cartridge (12) by a bayonet connection, and the direction of rotation of the adapter unit (26) for connecting the adapter unit (26) to the cartridge (12) corresponds to the same direction of rotation as the direction of rotation for screwing the threaded rod (20) into the adapter unit (26).

9. The apparatus (10) according to claim 1, characterized in that the threaded rod (20) has a length (L) of 15 cm to 23 cm, and / or the adapter unit (26) has a connection area (37) for insertion into the cartridge (12) having an inner diameter (D) of 3.3 cm to 4.0 cm.

10. The apparatus (10) according to claim 1, characterized in that at least a portion of the adapter unit (26), the handle (24), and / or the threaded rod (20) is made of polyamide, polyketone, polysulfone, and / or polyoxymethylene.

11. Use of the apparatus (10) according to claim 1 for extruding 50g to 130g of bone cement (15) from a cartridge (12).

12. A system for extruding bone cement (15), comprising a cartridge (12) for bone cement (15) and the apparatus (10) described in claim 1.

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