Device, use and system for extruding bone cement

Abstract

The invention relates to a device for extruding bone cement from a cartridge, to the use of the device and to a system for extruding bone cement. A device (10) for extruding bone cement (15) from a cartridge (12) comprises a threaded rod (20) having an external thread (22), a handle (24) for rotating the threaded rod (20), and an adapter unit (26) for mechanical connection to the cartridge (12) for bone cement (15). 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 (66) of the external thread (22) does not exceed 370 mm2. This makes particularly easy extrusion of highly viscous bone cement.

Description

[0001] The invention relates to a device for pressing bone cement from a cartridge, the use of the device and a system for pressing bone cement.

[0002] Bone cement is usually produced by mixing a powder with a liquid. For example, polymethyl methacrylate (PMMA) bone cement is known, which consists of a liquid monomer component and a powder component. The monomer component usually contains the monomer methyl methacrylate, in particular an activator (such as N, N-dimethyl-p-toluidine) dissolved therein. The powder component (also referred to as bone cement powder) has one or more polymers produced by polymerization, preferably suspension polymerization, based on methyl methacrylate and a comonomer (such as styrene, methyl acrylate or similar monomers), and in particular a radiopaque material and / or an initiator dibenzoyl peroxide. When the powder component is mixed with the monomer component, a plastically deformable paste is produced, i.e., actual bone cement (also referred to as bone cement paste), for example, by swelling of the polymer of the powder component in methyl methacrylate. When the powder component is mixed with the monomer component, the activator N, N-dimethyl-p-toluidine, for example, reacts with dibenzoyl peroxide to form free radicals. The free radicals formed can initiate free radical polymerization of methyl methacrylate. As the polymerization of methyl methacrylate proceeds, the viscosity of the cement can increase until it solidifies.

[0003] PMMA bone cement is mainly used for anchoring the intraarticular prosthesis in the bone permanently. Generally speaking, 50g to 125g or more of cement is used to anchor the intraarticular prosthesis. Bone cement is needed during the surgical operation of the patient, and bone cement should be provided in time. This is the main application field of the present invention.

[0004] Polymethylmethacrylate bone cement can be mixed by mixing the cement powder with the monomer liquid in a suitable mixing beaker with the aid of a spatula. In the process, air bubbles may become incorporated into the bone cement, and this may have a negative impact on the mechanical properties of the hardened bone cement. Other disadvantages are the need to manually measure the amount of cement and the need for thorough mixing, both of which cannot always be ensured.

[0005] Vacuum cementing systems are known for preventing air from being included in bone cement; the following are mentioned as examples: US 6 033 105 A, US 5 624 184 A, US 4 671 263 A, US 4 973 168A, US 5 100241A, WO 99 / 67015A1, EP 1 020 167A2, US 5 586 821A, EP 1 016 452 A2, DE 36 40 279A1, WO 94 / 26403A1, EP 1 005 901A2, EP 1 886 647 A1, US 5 344 232 A. A further development of cementing technology is represented by cementing systems in which both cement powder and monomer liquid are already packaged in separate compartments and are mixed with one another directly before applying the cement in the cementing system. Such closed fully pre-filled mixing systems or similar systems are described in particular in documents EP 0 380 867 B1, EP 0 796 653 B1, EP 0 692 229 A1, DE 10 2009 031178 B3, US 5 997 544A, US 6 709 149 B1, WO 00 / 35506 A1 and EP 0 796 653 A2.

[0006] WO9416951A1, EP1741413B1, EP3054880B1 and DE19718648A1 disclose mixing devices in which external devices for pressing out bone cement are used. Mixing devices or similar systems are known from US8662736B2 and EP3093067B1 in which a vacuum is applied to enable the transport or mixing of certain components or bone cement. EP2393456B1 describes a mixing device in which a liquid is pressed into a powder by means of an overpressure.

[0007] Manually operated discharge devices are based, for example, on a manually movable lever system that drives a push rod or a toothed rack and is connected to a bone cement cartridge. By repeatedly tilting the lever, the push rod or the toothed rack moves in the direction of a discharge piston of the cartridge, wherein the discharge piston presses out polymethylmethacrylate bone cement from the cartridge (with a discharge tube attached to its front) by moving in the direction of the cartridge head. Such or similar discharge devices are disclosed in US589344A, US5638997A and WO9416951A.

[0008] Screw systems are commonly used to remove a small amount of bone cement of up to about 10g of bone cement, and are used to stabilize fractured vertebral bodies. These screw systems known so far only have low mechanical load-bearing capacity and are not suitable for discharging a larger amount of PMMA bone cement of at least 50g. Examples of such discharging devices or similar devices are disclosed in US6676663B2, US2012224452A1, CN218220290U and CN213190021U.

[0009] The object of the present invention is to enable a particularly simple manual discharge of larger quantities of bone cement. In particular, a particularly simple and cost-effective device is produced which eliminates at least some of the disadvantages of the prior art.

[0010] This object is achieved by a device for mixing bone cement according to claim 1 and by a use and a system according to the independent claims. Advantageous embodiments are specified in the dependent claims.

[0011] This object is achieved by a device for pressing out bone cement. The device comprises a threaded rod with an external thread, 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 an internal thread for the threaded rod. In one embodiment, the outer surface of the thread of the external thread is at most 370 mm. 2 .

[0012] It has become apparent that the outer surface has a large influence on the friction losses when the threaded rod is rotated in the adapter unit and therefore on the force required to expel the bone cement. The outer surface is a measure of the surface area of ​​the outer thread that contacts the inner thread. The friction generated is therefore proportional to the outer surface. Tests have shown that it is irrelevant whether the reduction of the outer surface is achieved by reducing the thread depth, increasing the flank angle, reducing the diameter of the threaded rod, reducing the pitch or other measures, or by a combination of different measures. Only the absolute value of the outer surface is relevant.

[0013] Bone cement is usually highly viscous. Therefore, usually a particularly high force is necessary to squeeze out the bone cement. For example, squeezing out 130g of highly viscous PMMA bone cement from a bone cement cartridge may require a driving force of up to 2kN, which corresponds to a gravity of about 200kg. Therefore, it is necessary to reduce friction so that bone cement can be squeezed out with less manual force. In this way, even individuals with weaker physical strength can operate the device effortlessly. This is particularly important because bone cement continues to solidify over time after mixing, and therefore the force required for pressing increases over time. Tests show that in the case of the described maximum outer surface of the thread of the external thread, any user can easily discharge bone cement by manually rotating the handle. In the case of a larger outer surface, static friction and sliding friction make it very difficult to discharge, and therefore cause difficulty in handling.

[0014] The device can be made of plastic material or plastic material with metal. As in the case of cement guns, complex mechanisms are not necessary. No levers, bolts, pins, clamps, locking elements, racks and / or gears are required. The force required to squeeze out the bone cement is lower than the force required in the case of conventional devices (such as cement guns).

[0015] The device according to the invention is easy to handle, since complicated operation of the gun is not necessary. Discharging can be achieved simply by rotating the handle.

[0016] A thread turn is the helix of a thread over a distance corresponding to a full relative rotation of 360°. That is, one turn is taken into account. The outer surface is the area of ​​the external thread that can contact the corresponding internal thread. The outer surface of the thread turn consists, for example, of the surface of the first (e.g., upward) thread flank, the surface of the second (e.g., downward) thread flank, the surface in the region of the peak of the thread (which, for example, can extend parallel to the longitudinal axis and / or can be located between the thread flanks) and a further surface in the region of the depression or valley of the thread (which can be located between two thread flanks). Over one turn, these four surfaces are added together. In other words, the surface area between two adjacent peaks or valleys of the thread is taken into account. The rounded portion or transition portion between the individual surfaces is also part of the outer surface. Therefore, the corresponding characteristic values ​​of the external thread of the threaded rod can be applied to the internal 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 outwardly facing surface therebetween in the region of the thread crests defining the outer diameter of the external thread, and the outwardly facing surface in the region of the thread valleys defining the inner diameter of the external thread.

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

[0019] The threaded rod is designed to be rotated by manually rotating the handle. Specifically, for this purpose, the handle is connected to the threaded rod for joint rotation. The internal thread interacts with the external thread of the threaded rod in a manner that the threaded rod can rotate relative to the internal thread. The internal thread and the external thread are corresponding. Due to the interaction between the threaded rod and the adapter unit, the rotation of the threaded rod causes an axial translation relative movement between the threaded rod and the adapter unit. The extension direction of the threaded rod defines the axial direction of the device. The threaded rod is preferably guided through the passage so that the internal thread engages with the external thread. However, the threaded rod and the adapter unit can also be provided separately, so that the user must first screw the threaded rod into the adapter unit before using the threaded rod as intended.

[0020] The adapter unit is designed to be mechanically attached to a cartridge containing bone cement. Specifically, a connection for joint rotation is provided at least in the rotation direction of the threaded rod, so that rotating the threaded rod does not damage or loosen the attachment of the adapter unit to the cartridge. Typically, the adapter unit includes one or more first fastening members, and the cartridge includes one or more second fastening members, which are adapted to interact with each other and thus establish mechanical fastening. For example, the cartridge may have an external thread, and the adapter unit may have a corresponding internal thread. The passage of the adapter unit is specifically located in the center.

[0021] When the adapter unit is attached to the cartridge, the axial relative movement of the threaded rod relative to the adapter unit and therefore relative to the cartridge causes the end of the threaded rod away from the handle to penetrate into the cartridge and thus squeeze out bone cement from the cartridge. In this way, bone cement can be squeezed out from the end of the cartridge opposite to the adapter unit.

[0022] Specifically, the device includes a pressure element at the end of the threaded rod away from the handle, which is used to apply pressure to the bone cement in the cartridge. The pressure can be applied directly or indirectly. For example, the pressure element can press directly on the bone cement, or press on another element (such as a piston of the cartridge), which in turn presses on the bone cement.

[0023] In one embodiment, the outer surface of the thread turns of the external thread is at least 230 mm 2 .

[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 diameter of the threaded rod will be so small that shearing of the outer threads and / or torsion or buckling of the threaded rod may occur.

[0025] The pitch of the external thread also affects the force required for discharge. The pitch of the external thread is the distance covered in one turn measured in the axial direction. Generally speaking, too short pitch leads to very high turns ratio, and therefore leads to increased effort during use, because more rotations must be performed to discharge bone cement. This may lead to requiring too much time, which is undesirable, particularly during surgery and / or when bone cement gradually hardens. Generally speaking, too long pitch leads to low turns ratio, and therefore leads to very high force for discharging bone cement. In addition, if the pitch is too steep, the self-locking function may be weakened or eliminated, which then unnecessarily complicates the operation. The specific values ​​of these effects depend on different conditions, such as the material used and the property of the corresponding surface.

[0026] In one embodiment, the pitch of the external thread is at least 1 mm and / or at most 7 mm. In tests, it has been shown that this is particularly effective. Specifically, the pitch is at least 2 mm, preferably at least 3 mm, particularly 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 external thread of the threaded rod is at least 12 mm and / or at most 17 mm.The outer diameter means the largest diameter measured between the two largest crests of the thread, ie the diameter of an imaginary cylinder enclosing the external thread.

[0028] Specifically, the outer diameter is at least 13.5 mm and / or at most 15 mm. In one embodiment, the outer diameter is about or exactly 14 mm. An outer diameter less than 12 mm is not suitable for withstanding the forces or moments that occur. Too large an outer diameter increases friction and therefore the forces required for discharge.

[0029] In one embodiment, the internal thread of the adapter unit contains at least 2 and / or at most 7 thread turns. This means that the number of revolutions is necessary to fully screw the threaded rod into the internal thread. Generally speaking, too few threads in the adapter unit lead to low holding force, low strength and / or high loads on the individual thread turns. Generally speaking, too many thread turns lead to increased friction and therefore the high force required to discharge bone cement. It has been proven that the accompanying drawings are particularly useful.

[0030] In particular, the internal thread contains at least 3 thread turns, preferably at least or exactly 4 thread turns and / or at most 6 thread turns, preferably at most 5 thread turns. This has proven to be the best effect among the above-mentioned effects.

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

[0032] In one embodiment, the external thread of the threaded rod has a thread depth of at least 1mm and / or 4mm at the most. In principle, too shallow a thread depth causes the strength of the reduction on the thread and / or the mechanical stress of the increase. Generally speaking, too deep a thread depth causes the friction that increases and therefore discharges the required high force of bone cement. It has been shown that described accompanying drawing is particularly useful.

[0033] In particular, the thread depth does not exceed 2 mm and / or is approximately or exactly 1.5 mm. This has proven to be optimal with regard to the effects described.

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

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

[0036] The pressure element can be made completely or partially from metal or plastic material, for example from glass-fiber-reinforced plastic material and / or polyamide.

[0037] In one embodiment, the pressure element is constructed in two parts. A first part of the pressure element is connected to the threaded rod for joint rotation. A second part of the pressure element is connected to the first part for rotation about the longitudinal axis of the threaded rod.

[0038] The second part is used to apply pressure to the bone cement or to a part of the cartridge. The first part is used to connect the second part to the threaded rod and / or transmit the compression force of the threaded rod to the second part. A lubricant (such as silicone) can be provided between the first part of the pressure element to ensure a particularly smooth relative rotation between the first part and the second part. In one embodiment, the second part at least partially or circumferentially surrounds the first part. In other words, the second part is engaged behind the first part. This ensures that the first part and the second part do not separate from each other. This prevents the axial movement of the second part away from the first part and therefore prevents the 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 is flat and / or smooth. This allows a particularly smooth relative rotation. In particular, the surface of the second part facing the first part and / or the surface facing the second part is made of metal.

[0040] In one embodiment, the adapter unit has a recess. Specifically, the recess is arranged in the axial direction between the connection elements or connection areas of the adapter unit for mechanical connection to the cartridge of the adapter unit and / or mechanical connection to the internal thread or passage. The recess is designed to at least substantially accommodate the pressure element.

[0041] In particular, the recess is circular in shape and / or centrally arranged when viewed along the longitudinal axis of the threaded rod. In particular, the recess is cylindrical in shape. The recess is used to accommodate the pressure element. This means that the pressure element does not protrude beyond the recess or does not protrude significantly in the direction of the connecting element. This ensures that the connection area of ​​the cartridge, with which the adapter unit can be plugged onto the cartridge, for example, remains free. The recess may have an extension in the axial direction of, for example, at least 3 mm, preferably 4 mm and / or at most 10 mm, in particular 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 may be completely accommodated in the recess.

[0042] In one embodiment, the threaded rod includes an inner rod (eg, a metal rod) and / or a casing (eg, a plastic casing).

[0043] The inner rod produces a mechanically stable threaded rod. In particular, the rod is not rotationally symmetrical. This ensures a positive connection between the material of the rod (e.g. metal) and the material of the casing (e.g. plastic material). For example, the rod can be hexagonal or square. In particular, a metal rod having or made of stainless steel (such as 316L) is used.

[0044] In particular, the rod is completely covered by the plastic material. In particular, the thread is made of the plastic material. This provides a particularly smooth thread. 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. Too small a diameter may cause the threaded rod to twist and / or buckle under full load. Too large a diameter increases the diameter of the threaded rod and thus increases friction.

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

[0047] The adapter unit thus comprises a connection element for establishing a bayonet connection with the cartridge. The cartridge in particular comprises a corresponding connection element. This enables 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 therefore the threaded rod rotate to press the bone cement out of the cartridge. During this rotation, the connection is pushed toward the connection position. This prevents a rotation that would cause the connection to become loose or loose.

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

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

[0051] The connection area can be plugged onto one end of the cartridge. In the case of a threaded connection or a bayonet connection, this can be achieved, for example, by screwing on or screwing off. The connection area can have an inner diameter of at least 3 cm, preferably at least 3.3 cm, in particular at least 3.5 cm and / or at most 4.0 cm, in particular at most 3.8 cm. The inner diameter of the connection area corresponds substantially to the outer diameter of the cartridge. It has been shown that such a diameter is particularly suitable for quickly and with reasonable effort to discharge a desired amount of bone cement (e.g., at least 50 g and / or at most 130 g).

[0052] In one embodiment, at least part of the adapter unit, the handle, and / or the 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 aspect is the use of a device according to any of the preceding claims for pressing out an amount of at least 50 g and / or at most 130 g of bone cement from a cartridge. All features, advantages and configurations of the above-described device also apply to this use and vice versa.

[0054] Specifically, PMMA bone cement is pressed out. Specifically, this is done in order to anchor the endoprosthesis in human bone tissue. Specifically, the cartridge is a cartridge of a cementing system for anchoring the endoprosthesis in human bone tissue.

[0055] Another aspect of the present invention is a system for pressing out bone cement, which comprises a cartridge for bone cement and a device according to the present invention for pressing out bone cement. Specifically, the cartridge holds bone cement or is used to produce at least one component of bone cement. All features, advantages and embodiments of the above-mentioned device and purposes are also applicable to this system, and vice versa.

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

[0057] The cartridge may be connected at the end facing away from the adapter unit to one or more suitable hoses and / or one or more suitable tubes in order to transport the bone cement to the desired location.The one or more casting moulds of the spacer may also be filled with bone cement.

[0058] Another aspect of the present invention is a method for pressing bone cement from a cartridge, wherein the handle of a device according to the present invention is manually rotated so that bone cement is pressed from the cartridge. All features, advantages and embodiments of the above-mentioned device, uses and system also apply to this method, and vice versa.

[0059] The following also explains in more detail exemplary embodiments of the present invention with reference to the accompanying drawings. Unless otherwise indicated, the features of the exemplary embodiments may be combined with the claimed object individually or in multiples. The scope of protection claimed is not limited to the exemplary embodiments.

[0060] In the attached picture:

[0061] Figure 1 : is a perspective view of a device according to the invention with an alternative embodiment of an adapter unit,

[0062] Figure 2 : is a cross-sectional view of a device according to the present invention,

[0063] Figure 3 : is another cross-sectional view of the device according to the present invention,

[0064] Figure 4 : is another cross-sectional view of the device according to the present invention,

[0065] Figure 5 : is a cross-sectional view of the use of the device according to the present invention,

[0066] Figure 6 : is a further cross-sectional view of the use of the device according to the present invention, and

[0067] Figure 7 : is an enlarged detail of the threaded rod.

[0068] Figure 1The device 10 for pressing bone cement out of a cartridge according to the invention comprises an adapter unit 26 having a connection region 37 for mechanical connection to the cartridge. In the embodiment shown here, the connection region 37 can be plugged or screwed onto a corresponding region of the cartridge, such as Figure 5 and Figure 6 In the embodiment shown here, the adapter unit 26 has a connecting element 29 for producing a bayonet connection. The direction of rotation for tightening the bayonet connection corresponds to the direction of rotation for screwing in the threaded rod 20.

[0069] The device also includes a threaded rod 20 having an external thread 22. The threaded rod 20 passes through the passage 27 so that the external thread 22 engages with the internal thread located in the passage 27. A manually operated handle 24 for rotation is located on the end of the threaded rod 20 shown on the right. When the threaded rod 20 is rotated, the threaded rod moves axially through the adapter unit 26 so that bone cement can be pressed out.

[0070] At the end of the threaded rod 20 remote from the handle 24, the threaded rod 20 is designed to exert pressure or force on the bone cement. For this purpose, there may be a pressure element, for example Figure 2 A pressure element 30 is shown.

[0071] The alternative adapter unit 26 is shown in a dotted circle. This is designed essentially as the adapter unit 26 shown below and described above, but additionally comprises a grip 50. The grip can have the form of a spike extending in the radial direction. The grip 50 serves as a bearing seat during the manual rotation of the handle 24. The user can rotate the handle 24 with one hand and simultaneously fasten the adapter unit 26 or the cartridge connected to the adapter unit to the grip 50 with the other hand. This makes it possible to have a lower holding force and therefore an easier rotation. The discharge of bone cement is further simplified.

[0072] Figure 2 The device 10 is shown in a cross-sectional view along the central longitudinal axis of the threaded rod 20. Figure 1 To avoid repetition, only Figure 1 The difference.

[0073] As can be seen, the pressure element 30 is arranged at the end of the threaded rod 20 away from the handle 24. The pressure element 30 is used to directly or indirectly apply pressure to the bone cement so as to press it out of the cartridge. For example, the pressure element 30 can move a piston of the cartridge, which in turn presses the bone cement out of the cartridge.

[0074] The pressure element 30 is constructed in two parts. The first part 31 is firmly connected to the threaded rod 20 so that when the threaded rod 20 rotates, the first part rotates with the threaded rod. The second part 32 is rotatably connected to the first part 31 so that when the threaded rod 20 rotates, the second part 32 does not rotate. In this way, no rotational movement is applied to the bone cement 15 and / or to the piston, but only axial pressure. The contact surfaces of the first part 31 and the second part 32 are preferably flat and smooth to achieve smooth rotation.

[0075] It can also be seen that the threaded rod 20 has an inner core, a metal rod 40 in the example shown here, and a sheath, a plastic sheath 41 in the example shown here. The metal rod 40 extends centrally inside the threaded rod 20 and contributes significantly to the mechanical stability of the threaded rod 20. The plastic sheath 41 forms the outer thread 22 and protects the metal rod 40 from external influences. The metal rod 40 is preferably not rotationally symmetrical in order to ensure that it is connected to the handle 24 for joint rotation.

[0076] Figure 2 Also shown is an internal thread 28 in the passage 27 of the adapter unit 26. The internal thread contains 4 or 5 thread turns. The external thread 22 as well as the internal thread 28 have a pitch between 3 mm and 6 mm.

[0077] Figure 3 and Figure 4 The cross-section along the central longitudinal axis shows Figure 2 Here, too, only the additional features are discussed in order to avoid repetition. Figure 3 In, as in Figure 1 and Figure 2 As in FIG. 1 , the threaded rod 20 is shown in a position completely unscrewed from the adapter unit 26. In contrast, Figure 4 The position in which the threaded rod 20 has been partially rotated through the adapter unit 26 is shown, as occurs when pressing out bone cement.

[0078] It is shown that the adapter unit 26 has a recess 35, in which the pressure element 30 can be completely accommodated, as shown in FIG. Figure 3 In this way, the connection region 37 of the adapter unit 26 shown on the left remains free of the pressure element 30. The connection region 37 can thus be placed on the corresponding end of the cartridge or plugged or screwed onto the end without interfering with the pressure element 30.

[0079] Figure 3Also shown are some dimensions of the device 10. The threaded rod 20 has a length L of between 18 cm and 20 cm. The length L is measured between the outermost regions where the outer thread 22 is located. The connection region 37 of the adapter unit 26 has a diameter D of between 34 mm and 40 mm. The diameter of the connection region 37 corresponds approximately to the outer diameter of the corresponding connection region of the cartridge to be connected.

[0080] It can be seen that the second part 32 of the pressure element 30 surrounds the first part 31 of the pressure element 30 and / or forms a joint 34 with the first part. On the right-hand side, the in particular circumferential outer edge of the second part 32 extends inwardly and engages behind the radial outer edge of the first part 31 .

[0081] The first part 31 and / or the second part 32 may be designed in the form of a plate.The second part 32 may have a diameter of at least 20 mm and / or at most 30 mm, for example approximately or exactly 25 mm.

[0082] In addition, the outer diameter D of the threaded rod 20 is shown. A , which is measured in the radial direction between the crests of the external thread 22. The outer diameter D in the example shown here is A Between 13.5mm and 15mm.

[0083] Figure 5 and Figure 6 The use of the device 10 according to the invention with different cartridges 12 is shown. The connection area 37 of the adapter unit 26 is placed on the end of the cartridge 12 as described and is mechanically fastened to the end. The cartridge 12 has an outlet opening at the opposite end, to which, for example, a tube 51 for discharging bone cement 15 is connected. The bone cement 15 is inside the cartridge. Typically, the cartridge 12 also includes a piston 13, which is at least substantially sealed against the inner wall of the cartridge 12. The pressure element 30 of the device 10 is designed, for example, to exert an axial pressure on the piston 13 in order to press the bone cement 15 out of the cartridge. Figure 5 The beginning of the pressing process is shown, in which the pressure element 30 and the piston 13 are pressed to the left until the bone cement 15 lies flat against the piston 13 . Figure 6 This is a further pressing process in which, by continued rotation of the handle 24 , the bone cement 15 has been transported through the tube 51 and out of the tube.

[0084] Figure 7 is an enlarged section through the threaded rod 20. This includes the inner metal rod 40 and the plastic sheath 41 which completely surrounds the metal rod 40. The outer diameter D of the threaded rod 20 is shown. A , which corresponds to the maximum diameter between the crests on both sides of the external thread 22. In addition, the inner diameter D of the threaded rod 20 is shown. I, which corresponds to the smallest diameter between the depressions or valleys on both sides of the external thread 22. The thread has a thread depth between 1 mm and 2 mm. Therefore, the inner diameter D I With outer diameter D A The difference is between 2mm and 4mm.

[0085] For example, thread turns 66 are defined by dashed lines. A thread turn corresponds to a full rotation of the external thread 22 relative to the corresponding internal thread. The threaded rod 20 can be designed so that the outer surface of the thread turns 66 of the external thread 22 has a maximum of 370 mm. 2 In the example of a trapezoidal thread shown here, the outer surface of the thread is determined as the sum of an upper surface 61, which corresponds to the surface in the region of the thread crest, a lower surface 62, a first (upper row) flank surface 63 and a second (lower row) flank surface 64, wherein the upper surface corresponds to the surface in the region of the thread crest, and the lower surface corresponds to the surface in the region of the thread recess.

[0086] In one embodiment, the outer surface of the thread turns of the external thread is at most 450 mm 2 , especially up to 430 mm 2 , preferably up to 400mm 2 , particularly preferably at most 370 mm 2 In one embodiment, the outer surface of the thread turns of the external thread is at most 350 mm 2 , especially up to 330 mm 2 , preferably up to 300mm 2 In one embodiment, the outer surface of the thread turns of the external thread is at least 100 mm 2 , typically at least 130 mm 2 , especially at least 160 mm 2 , preferably at least 180mm 2 , particularly preferably at least 200 mm 2 , and further preferably at least 215 mm 2 In one embodiment, the outer surface of the thread turns of the external thread is at least 250 mm 2 , typically at least 280 mm 2 , especially at least 320mm 2 , and preferably at least 350mm 2 . These values ​​may be particularly suitable, depending on the design and material.

[0087] Example 1 :

[0088] The thread pitch is 4.5 mm and the outer diameter D of the external thread is manufactured. AThe invention discloses a device with a thread depth of 14 mm and a thread depth of 1.5 mm. This has been shown to be optimal for quickly and effortlessly pressing out up to 130 g of highly viscous bone cement from a bone cement cartridge. The process can be achieved in 1.5 minutes from the commercially available bone cement of the present application. The bone cement barrel is completely discharged with 130 g of bone cement. (2021 edition) achieved similar results.

[0089] Example 2 :

[0090] Selective laser sintering (SLS) was used to manufacture the adapter unit 26, the threaded rod 20 with a diameter of 30 mm, 25 mm, 20 mm and 14 mm and a pitch of 4.5 mm and 7.0 mm, and the matching handle from polyamide 12. Specifically, some or all of the parts were then chemically smoothed. The threaded rod 20 accommodates a standard stainless steel hexagonal rod inside. Specifically, the threaded rod was pressed into the plastic part after it was manufactured.

[0091] For the press-out tests, the commercially available mixing system PALAMIX and the polymethylmethacrylate bone cement PALACOS R+G from the applicant, and commercially available vancomycin hydrochloride were used.

[0092] The extrusion test was carried out by mixing two bags of PALACOS R+G (2×40.8g cement powder plus 2×18.5g monomer liquid) in a PALAMIX cartridge to obtain about 118g of bone cement. Subsequently, the bone cement was extruded using the manufactured device and the easy handling of the corresponding device was evaluated. The results are shown in the table below.

[0093]

[0094]

[0095] In addition, similar experiments were carried out with two packs of PALACOS R+G and two monomer ampoules each containing 18.5 g of monomer liquid, to which 4.0 g of vancomycin hydrochloride were added. The theoretical amount of cement is about 126 g of cement paste. Similar results were obtained as in the first series of experiments.

[0096] List of reference numbers

[0097] Device 10

[0098] Barrel 12

[0099] Piston 13

[0100] Bone cement 15

[0101] Threaded rod 20

[0102] External thread 22

[0103] Handle 24

[0104] Adapter unit 26

[0105] Path 27

[0106] Internal thread 28

[0107] Connecting element 29

[0108] Pressure element 30

[0109] Part 31

[0110] Part 232

[0111] Surface 33

[0112] Joint 34

[0113] Depression 35

[0114] Connecting area 37

[0115] Metal rod 40

[0116] Plastic shell 41

[0117] Grip 50

[0118] Tube 51

[0119] Upper surface 61

[0120] Lower surface 62

[0121] First flank surface 63

[0122] Second tooth side surface 64

[0123] Thread turns 66

[0124] Inner diameter D

[0125] Inner diameter D I

[0126] Outer diameter D A

[0127] Length L

Claims

1. A device (10) for pressing bone cement (15) out of a cartridge (12), the device comprising a threaded rod (20) having an external thread (22), a handle (24) for rotating the threaded rod (20) and an adapter unit (26) for mechanical connection to a cartridge (12) for bone cement (15), wherein the adapter unit (26) has a passage (27) having an internal thread (28) for the threaded rod (20), It is characterized in that The outer surface of the thread turns (66) of the external thread (22) is at most 370 mm 2 .

2. Device (10) according to the preceding claim, characterized in that The outer surface of the thread turns (66) of the external thread (22) is at least 230 mm 2 .

3. The device (10) according to any one of the preceding claims, characterized in that The pitch of the external thread (22) is at least 1 mm and / or at most 7 mm.

4. The device (10) according to any one of the preceding claims, characterized in that The outer diameter (D A ) is at least 12 mm and / or at most 17 mm.

5. The device (10) according to any one of the preceding claims, characterized in that The internal thread (28) of the adapter unit (26) contains at least 2 and / or at most 7 thread turns.

6. The device (10) according to any one of the preceding claims, characterized in that The external thread (22) of the threaded rod (20) has a thread depth of at least 1 mm and / or at most 4 mm.

7. The device (10) according to any one of the preceding claims, characterized in that The device (10) comprises a pressure element (30) having a flat surface (33) at the end of the threaded rod (20) remote from the handle (24) for applying pressure directly or indirectly to the bone cement (15) located in the cartridge (12).

8. Device (10) according to the preceding claim, characterized in that The pressure element (30) is constructed in two parts, wherein a first part (31) of the pressure element (30) is connected to the threaded rod (20) for joint rotation, and a second part (32) of the pressure element (30) is connected to the first part for rotation around the longitudinal axis of the threaded rod (20).

9. Device (10) according to any of the two preceding claims, characterized in that The adapter unit (26) has a recess (35), wherein the recess (35) is arranged in the axial direction between a connection area (37) or a connecting element (29) of the adapter unit (26) for mechanical connection to the cartridge (12) and the internal thread (28), wherein the recess (35) is adapted to at least substantially accommodate the pressure element (30).

10. The device (10) according to any one of the preceding claims, characterized in that The threaded rod (20) comprises an inner metal rod (40) and a plastic casing (41).

11. The device (10) according to any one of the preceding claims, characterized in that The adapter unit (26) is designed to be connected to the cartridge (12) by means of a bayonet connection, wherein the rotation direction of the adapter unit (26) for connecting the adapter unit (26) to the cartridge (12) corresponds to the rotation direction for screwing the threaded rod (20) into the adapter unit (26).

12. The device (10) according to any one of the preceding claims, characterized in that The threaded rod (20) has a length (L) of between 15 cm and 23 cm and / or the adapter unit (26) has a connection area (37) for plugging onto a cartridge (12), wherein the connection area (37) has an inner diameter (D) of between 3.3 cm and 4.0 cm.

13. The device (10) according to any one of the preceding claims, characterized in that At least parts of the adapter unit (26), the handle (24), and / or the threaded rod (20) are made of polyamide, polyketone, polysulfone and / or polyoxymethylene.

14. Use of the device (10) according to any of the preceding claims for pressing an amount of bone cement (15) between 50 g and 130 g from a cartridge (12).

15. A system for extruding bone cement (15), comprising a cartridge (12) for bone cement (15) and a device (10) according to any one of claims 1 to 13.

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