DEVICE AND METHOD FOR PRODUCING SPACERS WITH A VARIABLE HEAD

Abstract

The invention relates to a device for producing a spacer having a casting mold, wherein the casting mold has a stem mold and a mold cavity with a spherical surface-shaped inner surface, wherein the stem mold and the mold cavity delimit a common interior, at least one filling opening and at least one vent element, wherein the stem mold is dimensionally stable on injection of bone cement paste into the casting mold, while, on injection of bone cement paste into the casting mold, the mold cavity is expandable at least in the region of the spherical surface-shaped inner surface by pressure imparted by the injected bone cement paste. The invention also relates to a method for producing spacers using such a device.

Claims

1. A device for producing a spacer by curing bone cement paste, wherein the spacer is provided in the medical field for temporarily replacing a joint or part of a joint comprising an articulating surface of a head of the joint, in particular for temporarily replacing a hip joint or a shoulder joint, the device comprising: a casting mold for molding the spacer from bone cement paste, wherein the casting mold has a stem mold for molding a stem and a neck and the casting mold has a mold cavity with a spherical surface-shaped inner surface for molding a sliding surface of a head of the spacer, wherein the stem mold and the mold cavity delimit a common interior, such that the head of a spacer molded with the casting mold is connected as one part via the neck to the stem; at least one filling opening for injecting a bone cement paste into the casting mold; and at least one vent element which connects the common interior of the casting mold in a gas-permeable manner to the surroundings of the casting mold, wherein the stem mold is dimensionally stable on injection of bone cement paste into the casting mold, and wherein, on injection of bone cement paste into the casting mold, the mold cavity is expandable, at least in the region of the spherical surface-shaped inner surface, by pressure imparted by the injected bone cement paste.

2. The device according to claim 1, characterized in that the at least one vent element is permeable to gases and is impermeable to bone cement paste, in particular to polymethyl methacrylate bone cement paste (PMMA bone cement paste), and/or the at least one vent element is arranged in the mold cavity or the at least one vent element is a plurality of vent elements, wherein at least one of the plurality of vent elements is arranged in the mold cavity and at least one of the plurality of vent elements is arranged in the stem mold.

3. The device according to claim 1, characterized in that the mold cavity is radially expandable at least in the region of the spherical surface-shaped inner surface, by the pressure imparted by the injected bone cement paste, and/or the mold cavity is elastically expandable, at least in the region of the spherical surface-shaped inner surface, by the pressure imparted by the injected bone cement paste.

4. The device according to claim 1, characterized in that the stem mold and the mold cavity are connected or connectable to one another in a liquid-tight manner via a flange or an adapter element, wherein an expandable part of the mold cavity, which comprises the spherical surface-shaped inner surface, is fastened or fastenable with an annular mount to a flange of the stem mold or the adapter element, such that a peripheral annular disk of the expandable part of the mold cavity is arranged between the annular mount and the flange and seals the connection, wherein the annular mount is particularly preferably screwed or screwable to the flange of the stem mold.

5. The device according to claim 1, characterized in that the device has a fastening element for fastening the mold cavity to the stem mold, wherein the fastening element is detachable and comprises a plurality of screws.

6. The device according to claim 5, characterized in that the fastening element has clamping plates.

7. The device according to claim 1, characterized in that the at least one filling opening is connected on a side remote from the casting mold to a port for liquid-tight connection of a bone cement cartridge, wherein the port is suitable for pressure-tight connection of a bone cement cartridge, wherein the port has a thread and a circumferential seal and/or a circumferential sealing face or a circumferential sealing edge.

8. The device according to claim 1, characterized in that, at least in the region of the spherical surface-shaped inner surface, the mold cavity expands by injection of further bone cement paste into the casting mold already completely filled with bone cement paste, while the stem mold receives no additional bone cement paste and remains dimensionally stable.

9. The device according to claim 1, characterized by a valve seat, which is connected to the casting mold in the region of the at least one filling opening, wherein the valve seat has an in places closed head side with at least one first feed-through, wherein the at least one first feed-through opens into the at least one filling opening, a valve body which is mounted so as to be rotatable relative to the valve seat and which has a sealing face, wherein the sealing face is oriented in the direction of the in places closed head side of the valve seat, wherein at least one second feed-through is arranged in the sealing face; wherein the valve seat and the valve body together form a valve, wherein the valve is reversibly transferable into an open position and a closed position by rotation of the valve body relative to the valve seat, wherein, in the open position of the valve, the at least one first feed-through of the valve seat and the at least one second feed-through of the valve body are located above one another at least in places and provide a connection permeable to bone cement through the valve into the casting mold, wherein, in the closed position of the valve, the at least one first feed-through of the valve seat is covered by the sealing face of the valve body, wherein, in the closed position of the valve, the at least one filling opening of the casting mold is covered for bone cement paste.

10. The device according to claim 9, characterized in that the valve is connected on the side remote from the casting mold to a port for liquid-tight connection of a bone cement cartridge or the valve has such a port and/or the valve seat is connected to the casting mold so as not to be rotatable relative to the casting mold, preferably the valve seat is firmly and/or rigidly connected to the casting mold.

11. The device according to claim 9, characterized in that the valve is manually operable, preferably manually operable from outside the device, wherein the valve body is manually rotatable relative to the valve seat and the valve is transferable by rotation from the closed position into the open position and from the open position into the closed position.

12. The device according to claim 9, characterized in that the valve seat has an inner thread on the inside and the valve body has a matching outer thread on the outside, such that the valve body can be screwed into the valve seat and/or the port comprises, for liquid-tight connection of a bone cement cartridge, an inner thread in the valve body or an outer thread on the valve body, wherein an adapter element of the bone cement cartridge or on the bone cement cartridge preferably has a mating thread matching the inner thread or the outer thread.

13. The device according to claim 1, characterized in that the device has a bone cement cartridge for mixing bone cement starting components and for delivering mixed bone cement paste from the bone cement cartridge and has a bone cement cartridge for mixing polymethyl methacrylate bone cement starting components and for delivering mixed polymethyl methacrylate bone cement paste from the bone cement cartridge, wherein the bone cement cartridge contains the bone cement starting components for producing the bone cement in mutually separate regions.

14. The device according to claim 1, characterized in that the casting mold has at least three or four cavities, starting from an inner chamber of the casting mold, for receiving retaining pins, wherein the cavities are arranged in the stem mold and the stem mold is in two parts or three parts and the cavities are arranged in edges or in longitudinal flanges of at least one part of the two-part stem mold.

15. The device according to claim 1, characterized in that the device has a metal core which is to be arranged in the casting mold, wherein the metal core has bores for receiving retaining pins, wherein those bores which are to be arranged in the stem mold are arranged within the part of the metal core.

16. The device according to claim 1, characterized in that the spherical surface-shaped inner surface of the mold cavity has, in the unexpanded state, a diameter of at least 35 mm or of at least 40 mm and preferably of between 40 mm and 50 mm, and/or, in the maximally expanded state, has a diameter of at most 70 mm, wherein, in the unexpanded state, the diameter of the spherical surface-shaped inner surface of the mold cavity is smaller than the diameter of the spherical surface-shaped inner surface of the mold cavity in the expanded state.

17. The device according to claim 1, characterized in that the mold cavity consists, at least in the region of the spherical surface-shaped inner surface, of a rubber-elastic material.

18. The device according to claim 1, characterized in that the at least one filling opening contains a shut-off element which, in a closed state, prevents bone cement paste from flowing out of the casting mold through the at least one filling opening.

19. The device according to claim 1, characterized in that the stem mold comprises a length-variable adapter element with which the length of the neck of the spacer is able to be varied, said neck connecting the stem to the head of the spacer, wherein the adapter element is able to be varied in length by a screw connection.

20. The device according to claim 1, characterized in that the device has a plurality of dimensionally stable mating molds which are suitable for receiving the mold cavity, wherein the dimensionally stable mating molds enable a different degree of expansion of the mold cavity, such that, at least in the region of the spherical surface-shaped inner surface, expansion of the mold cavity is limited by the dimensionally stable mating molds to different diameters when the mold cavity is inserted into the respective dimensionally stable mating mold, wherein the dimensionally stable mating molds are embodied by at least one blister pack or a plastics shell with one or a plurality of indentations as the dimensionally stable mating molds, and/or the device has a check gage or a vernier caliper for measuring the current diameter of the spherical surface-shaped inner surface of the mold cavity, wherein the check gage or vernier caliper may be placed or is arranged on the outside of the mold cavity and wherein the diameter of the spherical surface-shaped inner surface of the mold cavity is preferably directly readable.

21. A method for producing a spacer for temporarily replacing a joint or part of a joint, in particular a hip joint or a shoulder joint, comprising an articulating surface of the joint, wherein the method is carried out with the device according to claim 1, the method having the following chronological steps: A) injecting bone cement paste through the at least one filling opening into the casting mold and simultaneously displacing air from the casting mold through the at least one vent element by injection of the bone cement paste; B) further injecting bone cement paste though the at least one filling opening into the casting mold, wherein injection of the bone cement paste expands the mold cavity at least in the region of the spherical surface-shaped inner surface, while the stem mold remains dimensionally stable; C) curing the bone cement paste in the casting mold; and D) removing the resultant molded and cured spacer from the casting mold.

22. The method according to claim 21, characterized in that, prior to step A), a bone cement cartridge is connected in liquid-tight manner to a port of the device, wherein the port is connected to the at least one filling opening in a liquid-permeable manner and in step A) the bone cement paste is pressed out of the bone cement cartridge into the casting mold.

23. The method according to claim 22, characterized in that a device according to claim 1 with a valve is used, wherein bone cement paste is injected in step A) through the valve in the open position into the casting mold, wherein a step B1) proceeds after step B) and before step C): B1) rotating the valve body relative to the valve seat and so transferring the valve into the closed position and shearing off the bone cement paste at the at least one first feed-through in the in places closed head side of the valve seat by rotation of the valve body relative to the valve seat, wherein a bone cement cartridge is then detached from a port which is connected to the at least one filling opening in a liquid-permeable manner.

24. The method according to claim 23, characterized in that the following intermediate steps proceed after step B1) and before step C): B2) connecting a new bone cement cartridge to the port of the device in a liquid-tight manner, wherein bone cement paste or starting components for producing the bone cement paste is or are present in the new bone cement cartridge; B3) rotating the valve body relative to the valve seat and so transferring the valve into the open position; B4) injecting the bone cement paste from the new bone cement cartridge through the valve in the open position into the casting mold; B5) rotating the valve body relative to the valve seat and so transferring the valve into the closed position and shearing off the bone cement paste at the at least one first feed-through in the in places closed head side of the valve seat by rotation of the valve body relative to the valve seat; and B6) detaching the new bone cement cartridge from the port; wherein steps B2) to B6) are preferably repeated once or multiple times with in each case new bone cement cartridges which contain bone cement paste or the starting components thereof until the casting mold is completely filled with bone cement paste and furthermore until, with the assistance of the bone cement paste, the mold cavity is expanded to the desired size at least in the region of the spherical surface-shaped inner surface.

25. The method according to claim 21, characterized in that the mold cavity of the casting mold is inserted into one of a plurality of dimensionally stable mating molds, wherein the dimensionally stable mating molds enable a different degree of expansion of the mold cavity, such that, at least in the region of the spherical surface-shaped inner surface, expansion of the mold cavity is limited by the dimensionally stable mating mold used to a specific diameter while the bone cement paste is pressed into the casting mold in order to expand the mold cavity.

26. The method according to claim 21, characterized in that a check gage or a vernier caliper for measuring the current diameter of the spherical surface-shaped inner surface of the mold cavity is used to read off the current diameter of the spherical surface-shaped inner surface of the mold cavity, wherein injection of the bone cement paste into the casting mold is preferably stopped once a desired diameter is reached.

27. The method according to claim 25, characterized in that the mold cavity of the casting mold is inserted into one of a plurality of dimensionally stable mating molds, wherein the dimensionally stable mating molds enable a different degree of expansion of the mold cavity, such that, at least in the region of the spherical surface-shaped inner surface, expansion of the mold cavity is limited by the dimensionally stable mating mold used to a specific diameter while the bone cement paste is pressed into the casting mold in order to expand the mold cavity.

28. The method according to claim 25, characterized in that a check gage or a vernier caliper for measuring the current diameter of the spherical surface-shaped inner surface of the mold cavity is used to read off the current diameter of the spherical surface-shaped inner surface of the mold cavity, wherein injection of the bone cement paste into the casting mold is preferably stopped once a desired diameter is reached.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0212] Further exemplary embodiments of the invention are explained below with reference to twenty-eight schematic figures but without thereby limiting the invention. Therein:

[0213] FIG. 1 shows a schematic perspective cross-sectional view of a first exemplary device according to the invention for producing a hip joint spacer;

[0214] FIG. 2 shows a schematic perspective external view of the first device according to the invention according to FIG. 1;

[0215] FIG. 3 shows a schematic perspective cross-sectional view of the first device according to the invention according to FIGS. 1 and 2 with the valve open;

[0216] FIG. 4 shows a schematic perspective cross-sectional view of the first device according to the invention according to FIGS. 1 to 3 with the valve closed;

[0217] FIG. 5 shows a schematic cross-sectional view of the first device according to the invention with the valve open prior to the filling of bone cement paste into a casting mold of the device;

[0218] FIG. 6 shows a schematic cross-sectional view of the first device according to the invention during the filling of bone cement paste into the casting mold;

[0219] FIG. 7 shows a schematic cross-sectional view of the first device according to the invention with a casting mold filled with bone cement paste;

[0220] FIG. 8 shows a schematic cross-sectional view of the first device according to the invention with a casting mold filled with bone cement paste with the valve closed;

[0221] FIG. 9 shows a schematic cross-sectional view of the first device according to the invention with the valve closed with an unexpanded mold cavity after removal of a bone cement cartridge and an adapter element from the casting mold;

[0222] FIG. 10 shows a schematic cross-sectional view of the first device according to the invention with the valve closed and a bone cement cartridge detached from the mold cavity;

[0223] FIG. 11 shows a schematic perspective view of a second exemplary device according to the invention for producing a shoulder joint spacer with an open two-part stem mold;

[0224] FIG. 12 shows a schematic perspective view of the second device according to the invention according to FIG. 11;

[0225] FIG. 13 shows a schematic perspective cross-sectional view of the second device according to the invention according to FIGS. 11 and 12 with an extended adapter element;

[0226] FIG. 14 shows a schematic perspective view of the second device according to the invention according to FIG. 13 with an open two-part stem mold and an extended adapter element;

[0227] FIG. 15 shows a schematic perspective external view of the closed second device according to the invention according to FIGS. 11 to 14;

[0228] FIG. 16 shows a schematic cross-sectional view of the second device according to the invention filled with bone cement paste from the bone cement cartridge;

[0229] FIG. 17 shows a schematic cross-sectional view of the second device according to the invention with the valve closed after removal of a bone cement cartridge and an adapter element from the casting mold;

[0230] FIG. 18 shows a schematic perspective external view of the closed second device according to the invention according to FIGS. 11 to 17 with an extended adapter element and expanded mold cavity dimensions indicated by dashed lines;

[0231] FIG. 19 shows a schematic perspective cross-sectional view of the second device according to the invention with an expanded mold cavity and with an extended adapter element;

[0232] FIG. 20 shows a perspective view of a spacer which has been produced using a second device according to the invention according to FIGS. 11 to 19;

[0233] FIG. 21 shows a perspective view of a spacer with an extended neck which has been produced using a second device according to the invention according to FIGS. 11 to 19;

[0234] FIG. 22 shows a schematic perspective view of a valve for a device according to the invention in the open state;

[0235] FIG. 23 shows a schematic perspective partial cross-sectional view of the valve according to FIG. 22 in the open state;

[0236] FIG. 24 shows a schematic perspective cross-sectional view through the valve according to FIGS. 22 and 23 in the open state;

[0237] FIG. 25 shows a schematic perspective view of the valve according to FIGS. 22 to 24 in the closed state;

[0238] FIG. 26 shows a schematic perspective partial cross-sectional view of the valve according to FIGS. 22 to 25 in the closed state;

[0239] FIG. 27 shows a schematic perspective cross-sectional view of the valve according to FIGS. 22 to 26 in the closed state; and

[0240] FIG. 28 shows a schematic cross-sectional view of the valve according to FIGS. 22 to 27 in the closed state.

DETAILED DESCRIPTION

[0241] FIGS. 1 to 11 are drawings showing various views of a first exemplary embodiment of a device according to the invention for producing a hip joint spacer and parts thereof.

[0242] The first device according to the invention is suitable and provided for producing a spacer for a hip joint. The device comprises a casting mold 1. The casting mold 1 may be constructed in multiple parts, in particular in three parts. FIGS. 1 and 3 to 11 show the casting mold 1 open or sectioned, such that the interior structure of the device is visible. The casting mold 1 may have a proximal mold cavity 32 for molding a head of the spacer and a distal stem mold 34 for molding a stem of the spacer. The shaping parts of the mold cavity 32 may be in one part and the shaping parts of the stem mold 34 may be in two parts (see FIG. 2). FIG. 2 shows all the parts of the casting mold 1. The mold cavity 32 may have a spherical surface-shaped inner surface in the form of a hemisphere. The spherical surface-shaped inner surface of the mold cavity 32 serves as a negative mold for forming a sliding surface of the head of the spacer. According to the invention, the mold cavity 32 is expandable in order to enable production of sliding surfaces with different radii or spacer joint heads (heads of spacers) with different diameters which are molded by the spherical surface-shaped inner surface of the mold cavity 32.

[0243] A filling opening 2 for the introduction of bone cement paste 50 may be formed on one side of the casting mold 1, which filling opening may be defined in each case in both parts of the stem mold 34 by a semicircular cylindrical opening. This filling opening 2 may form a valve seat 3 which may be embodied as part of the stem mold 34. The valve seat 3 may be firmly connected to the casting mold 1. The mold cavity 32 and thus the spherical surface-shaped inner surface of the mold cavity can be continuously expanded by injecting the bone cement paste 50 into the casting mold 1. The diameter of the head of a spacer fabricated with the device may consequently be variably adjusted.

[0244] The valve seat 3 may take the form of a hollow cylinder which, apart from two first feed-throughs 5, is closed on a head side 4 oriented in the direction of the filling opening 2. The two first feed-throughs 5 may be quadrant-shaped and may preferably be arranged rotated or offset relative to one another by 180° with regard to the cylinder axis of the valve seat 3. A valve body 6 may be arranged in the interior of the valve seat 3 so as to be axially rotatable relative to the valve seat 3. The valve body 6 may have a sealing face 7 or surface oriented in the direction of the head side 4 of the valve seat 3. The valve body 6 may be constructed as a stepped hollow cylinder, the front part of which can be screwed or put into the valve seat 3.

[0245] Two second feed-throughs 8 may be arranged in the sealing face 7. The two second feed-throughs 8 may, similarly to the first feed-throughs 5, be quadrant-shaped and may preferably be arranged rotated relative to one another by 180° with regard to the cylinder axis of the valve body 6. The valve seat 3 and valve body 6 together form a valve of the device. An adapter element 9 for liquid-tight connection of a bone cement cartridge 10 may be or have been screwed into the valve body 6 (see FIGS. 1 and 3 to 8). The bone cement cartridge 10 and the adapter element 9 may be part of the device according to the invention. The valve body 6 may on its open side, which is remote from the sealing face 7, be formed as a port 11 for connecting the adapter element 9.

[0246] The bone cement cartridge 10 may have on its front side a delivery tube 37 with a delivery opening 12 for delivering the bone cement paste 50 from the bone cement cartridge 10. The delivery opening 12 may be arranged together with the delivery tube 37 in the adapter element 9 and be delimited by the delivery tube 37. The adapter element 9 may close the bone cement cartridge 10 on its front side apart from the delivery opening 12 and optionally apart from a vacuum port 44. Sealing may be provided by arranging in the adapter element 9 a seal 13 in the form of an O-ring of rubber, which seals against the delivery tube 37. A mixer 36 with a plurality of mixing blades, with which the bone cement paste 50 can be mixed in the interior of the bone cement cartridge 10, may be fastened at the end of the delivery tube 37 pointing into the interior of the bone cement cartridge 10 before the bone cement cartridge 10 is connected to the valve. The delivery tube 37 may to this end be mounted in axially linearly and rotatably mobile manner in the adapter element 9.

[0247] The mold cavity 32 may consist of a rubber-elastic plastics material. As a result, the mold cavity 32 can be expanded with the assistance of the bone cement paste 50, as is visible in FIGS. 9 and 10. FIG. 9 here shows an unexpanded mold cavity 32 and FIG. 10 an expanded mold cavity 32. The wall thickness of the mold cavity 32 is uniform, such that the mold cavity 32 expands uniformly when a pressure is exerted in the interior of the mold cavity 32 via the bone cement paste 50.

[0248] The stem mold 34 may be inexpensively fabricated from plastics film and is dimensionally stable, such that, in contrast to the mold cavity 32, it cannot or cannot substantially be expanded by a pressure exerted by the bone cement paste 50 in the interior of the casting mold 1. The plastics film may have a plurality of layers. The two parts of the stem mold 34 may be fastened flush together via flanges 14. The mold cavity 32 and the stem mold 34 may likewise be connected flush together via a flange 35 of the stem mold 34 and an annular disk 23 of the mold cavity 32. By connecting the parts of the casting mold 1 via the flanges 14, 35 and the annular disk 23, the casting mold 1 may be closed to the outside. The annular disk 23 may be screwed via a segmented annular mount 21 to the flange 35. Screws 25 may to this end be screwed into fittings 27 having inner threads which match the screws 25. The two parts of the stem mold 34 may likewise be fastened together with screws 31 which are screwed into fittings 33 having inner threads which match the screws 31. In order to simplify positioning of the two parts of the stem mold 34 relative to one another and of the mold cavity 32 on the stem mold 34, pins 29 may be provided which can be put into recesses 39 on the opposing flange 14 or flange 35. The annular disk 23 seals the connection of the mold cavity 32 to the stem mold 34 in the manner of a sealing ring.

[0249] At least one vent element 15 having in each case at least one vent opening 19 may be arranged in the casting mold 1. At least one vent element 15 may be arranged at the mold cavity 32 so that it is possible to expel air from the interior of the casting mold 1. Air or gas can escape through the vent opening 19 from the interior of the closed casting mold 1 when a bone cement paste 50 is filled into the casting mold 1 through the filling opening 2. A porous filter 17 which is permeable to gases but impermeable to the bone cement paste 50 can be arranged in the vent element 15. In this way, the bone cement paste 50 is prevented from being able to escape through the vent opening 19 during filling of the casting mold 1 and consequently on the one hand impairing the shape of the head of the spacer and on the other hand allowing the pressure of the bone cement paste 50 in the mold cavity 32 to decline by outflow of bone cement paste 50 from the mold cavity 32. This ensures that the mold cavity 32 remains in the desired expanded state while the bone cement paste 50 begins to cure in the casting mold 1. It may be sufficient for the free cross-sectional area of the vent opening 19 to be so small that the bone cement paste 50 cannot escape through the vent opening 19 due to its viscid consistency.

[0250] A metal core 16 may be placed in the interior of the casting mold 1. The metal core 16 may consist of surgical steel or of titanium. Alternatively, it would theoretically also be possible to fabricate the metal core 16 from a plastics material such as PMMA. The metal core 16 may be connected to the stem mold 34 via retaining pins 18. The metal core 16 may be spaced from the internal wall of the casting mold 1 with the aid of the retaining pins 18, such that the bone cement paste 50 can flow right around the metal core 16. The metal core 16 brings about stabilization of the spacer. The retaining pins 18 may consist of PMMA. This can irreversibly bond to a bone cement paste 50 of PMMA.

[0251] The valve seat 3 may have an inner thread 20 on its inside. On the front half of the valve body 6 facing the sealing face 7, the valve body 6 may have on the outside thereof an outer thread 22 matching the inner thread 20 of the valve seat 3. The valve body 6 may be screwed with its outer thread 22 into the inner thread 20 of the valve seat 3.

[0252] The first feed-throughs 5 and the second feed-throughs 8 may be brought into overlap with one another by screwing the valve body 6 into the valve seat 3 until the limit stop is reached. The valve is then in the open state. In this open state, a bone cement paste 50 may flow through the first feed-throughs 5 and through the second feed-throughs 8 out of the bone cement cartridge 10 into the casting mold 1. By making a quarter rotation (by 90°) of the valve body 6 relative to the valve seat 3, i.e. by unscrewing the valve body 6 from the valve seat 3, the first feed-throughs 5 and the second feed-throughs 8 may be offset relative to one another, such that the sealing face 7 of the valve body 6 covers the first feed-throughs 5 of the valve seat 3 and the closed regions of the head side 4 of the valve seat 3 cover the second feed-throughs 8 of the valve body 6. The valve is then in the closed state. Due to the small stroke of the valve body 6 relative to the valve seat 3 in the event of a quarter rotation, the gap arising between the valve body 6 and the valve seat 3 is so narrow (less than 1 mm wide) that a bone cement paste 50 of a normal, let alone high, viscosity, is incapable of passing through the gap. This is particularly the case because the bone cement paste 50 is deflected from its actual direction of flow by 90° in the gap.

[0253] The reverse side of the valve body 6 may have an inner thread 24 arranged in the port 11. The adapter element 9 has on its front side an outer thread 26 which matches the inner thread 24. The adapter element 9 may accordingly be screwed into the port 11 of the valve body 6. In this way, a liquid-tight connection can be created between the bone cement cartridge 10 and the valve body 6 and thus into the casting mold 1. The inner thread 20 of the valve seat 3, the outer thread 22 of the valve body 6, the inner thread 24 of the valve body 6 and the outer thread 26 of the adapter element 9 may all have the same direction of rotation, i.e. all these threads are right-hand threads or left-hand threads. As a result, the valve can be opened by screwing the adapter element 9 into the port 11 and continuing to rotate the adapter element 9 in the same direction. At the same time, the valve body 6 also provides a seal relative to the valve seat 3.

[0254] The adapter element 9 may be or have been connected via a latching means 28 on the adapter element 9 to a mating latch 30 on a cylindrical wall of the bone cement cartridge 10. A circumferential seal 48 which seals the cylindrical wall of the bone cement cartridge 10 relative to the adapter element 9 may be provided for sealing.

[0255] The casting mold 1 may include the mold cavity 32 for forming the joint head (head) of the spacer and the stem mold 34 for forming the stem of a spacer. Moreover, an orifice for a lever 38 of the valve body 6 may be arranged in the casting mold 1 in the region of the filling opening 2. The lever 38 may be connected to the valve body 6. The valve body 6 can be rotated in the valve seat 3 with the lever 38. The orifice is preferably precisely large enough for the valve body 6 to be rotatable only by a maximum of a quarter rotation relative to the valve seat 3. As a result, with the assistance of the lever 38, the valve can be transferred manually from outside from the open state into the closed state or from the closed state into the open state.

[0256] In the region of the flanges 14, shapes 40 may be arranged in the stem mold 34 for cavities, in which shapes the retaining pins 18 may be arranged.

[0257] A vacuum port 44 which is capable of evacuating an interior of the bone cement cartridge 10 in which the bone cement paste 50 is mixed may be arranged in the adapter element 9. As a result, the bone cement paste 50 can be mixed under a vacuum.

[0258] A piston 46 for discharging the bone cement paste 50 from the bone cement cartridge 10 through the valve into the casting mold 1 may be arranged in the cylindrical interior of the bone cement cartridge 10. The piston 46 may to this end be cylindrically shaped on the outside and be sealed relative to the cylindrical interior via two circumferential seals 47. By advancing the piston 46, the bone cement paste 50 can be pressed out of the delivery opening 12 of the bone cement cartridge 10 into or through the open valve.

[0259] A porous disk 52 may be arranged in the adapter element 9. The porous disk 52 is impermeable to the bone cement paste 50 and its starting components. The vacuum port 44 can be covered by the porous disk 52. This prevents any bone cement powder as a starting component of the bone cement paste 50 from being able to penetrate into the vacuum port 44.

[0260] The course of a method according to the invention is shown in FIGS. 4 to 10 with reference to the first device according to the invention. First of all, the metal core 16 may be positioned with the retaining pins 18 in the stem mold 34. To this end, the retaining pins 18 may be arranged and retained at one end between the two parts of the stem mold 34 in the cavities formed by the shapes 40 and arranged with the other end in matching bores in the metal core 16. In order to fasten the two parts of the stem mold 34 together, the flanges 14 of the two parts of the stem mold 34 can firstly be positioned via the pins 29 in the recesses 39 and then the two parts of the stem mold 34 can be screwed together with the assistance of the screws 31. The casting mold 1 may then be closed by fastening the mold cavity 32 to the stem mold 34. The annular disk 23 may to this end be laid on the flange 35. The two half rings of the mount 21 can then be laid on the annular disk 23 and positioned via the pins 29 and the recesses 39. The mold cavity 32 can then be fastened to the stem mold 34 by tightening the screws 25, wherein the annular disk 23 seals the connection. The casting mold 1 is then closed with the metal core 16 therein and can be provided to mold a spacer.

[0261] A bone cement paste 50 can be mixed under a vacuum in the bone cement cartridge 10. The bone cement cartridge 10 can then be screwed with the adapter element 9 into the port 11 of the valve body 6. On screwing in the adapter element 9, the valve can be transferred into the open position by screwing the valve body 6 into the valve seat 3 until the limit stop is reached. FIGS. 1 and 5 show this situation.

[0262] The bone cement paste 50 is then pressed out of the bone cement cartridge 10 through the valve and through the overlapping first feed-throughs 5 and second feed-throughs 8 into the casting mold 1 by advancing the piston 46. FIG. 6 shows this situation. By closing the valve by manually operating the lever 38 and so rotating the valve body 6 by a quarter rotation relative to the valve seat 3, a new bone cement cartridge 10 can be attached at intervals if the volume of the bone cement paste 50 from a single bone cement cartridge 10 is not enough to fill the casting mold 1 completely. The bone cement paste 50 contained in the casting mold 1 cannot flow back out again since the first passages 5 and the second passages 8 are covered in the closed position of the valve and the gap therebetween is insufficient for the viscous bone cement paste 50 to be able flow through. Simultaneously, pressure from the bone cement paste 50 is maintained in the interior of the mold cavity 32 by the closed valve.

[0263] At some point, the casting mold 1 is filled with the bone cement paste 50. FIG. 7 shows this situation. Air or gas can escape from the casting mold 1 through the vent element 15 or through the vent openings 19 in the mold cavity 32. The mold cavity 32 can be expanded to the desired size by further injection of bone cement paste 50 (see FIG. 10 in comparison with FIG. 9). Radial expansion can be determined with the assistance of a check gage or a vernier caliper (not shown) for measuring the current diameter of the mold cavity 32. Since the wall thickness of the mold cavity 32 is known, the current diameter of the spherical surface-shaped inner surface of the mold cavity 32 is also determinable. Alternatively or additionally, a dimensionally stable mating mold (not shown) with a known and defined diameter may be provided into which the mold cavity 32 can be laid, such that the mold cavity 32 can only expand until it rests against the mating mold. In this way, the desired diameter of the head of the spacer produced with the device can be straightforwardly established. Once the desired radial expansion of the spherical surface-shaped inner surface of the mold cavity 32 has been reached, the valve can be closed.

[0264] By closing the valve with the lever 38, the bone cement paste 50 is sheared or cut off This situation is shown in FIGS. 4 and 8 show this situation. The bone cement cartridge 10 can be unscrewed and removed. Any remaining thin connections simply tear or break away. This situation is shown in FIGS. 9 and 10.

[0265] In this state, the bone cement paste 50 can be cured in the casting mold 1. The size or diameter of the head of the spacer here matches the diameter of the spherical surface-shaped inner surface of the expanded mold cavity 32. In order to avoid unevenness of the sliding surface of the spacer, it is preferred according to the invention that, even when producing spacers with heads having the smallest diameter, the mold cavity 32 is already slightly expanded such that the bone cement paste 50 is under pressure in the casting mold 1 while it cures.

[0266] Then, the spacer formed in this way is removed from the casting mold 1. The projecting retaining pins 18 may be cut off. Any sprue caused by the valve seat 3 and the first passages 5 can likewise be cut off and removed. Points or unevenness caused by the vent opening 19 may also be removed. The surface of the spacer can be polished and/or coated, for example with antibiotics.

[0267] Instead of a casting mold 1 for molding a hip joint spacer, it is also straightforwardly possible to use a casting mold for molding a different spacer.

[0268] FIGS. 12 to 19 are drawings showing various views of a second exemplary embodiment of a device according to the invention for producing a spacer for a shoulder joint and parts thereof. FIGS. 20 and 21 show a shoulder joint spacer which has been produced using such a second device according to the invention as the result of a method according to the invention, the method steps of which are shown chronologically in FIGS. 14 to 21.

[0269] The second device according to the invention is suitable and provided for producing a spacer 120, 130 (see FIGS. 20 and 21) for a shoulder joint. The device comprises a casting mold 61. The casting mold 61 may be constructed in multiple parts, in particular in four parts. FIGS. 12 to 14 and 16 to 19 show the casting mold 61 open or sectioned, such that the interior structure of the device is visible. The casting mold 61 may have a proximal mold cavity 92 for molding a head of the spacer and a distal stem mold 94 for molding a stem of the spacer. The shaping parts of the mold cavity 92 may be in one part and the shaping parts of the stem mold 94 may be in two parts (see FIG. 15). FIG. 15 shows all the parts of the casting mold 61. The mold cavity 92 may have a spherical surface-shaped inner surface in the form of a hemisphere. The spherical surface-shaped inner surface of the mold cavity 92 serves as a negative mold for forming a sliding surface of the head of the spacer. According to the invention, the mold cavity 92 is expandable in order to enable production of sliding surfaces with different radii or spacer joint heads (heads of spacers) with different diameters which are molded by the spherical surface-shaped inner surface of the mold cavity 92.

[0270] In contrast with the first device according to the invention, the casting mold 61 additionally has an adapter element 102 with an inner thread 103. The adapter element 102 can be screwed with its inner thread 103 onto a hollow cylinder 105 with a matching outer thread 107. The fitting 105 can be molded by the two parts of the stem mold 94. The adapter element 102 allows the mold cavity 92 to be variably spaced from the stem mold 94. The adapter element 102 and the interior shape of the hollow cylinder 105 shape the neck of a spacer 120, 130 produced with the second device according to the invention. The length of the neck of the spacer can be modified by screwing the adapter element 102 relative to the hollow cylinder 105 (see FIGS. 20 and 21). Such an adapter element 102 with a hollow cylinder 105 for adjusting the length of the neck of the spacer may in principle also be used in the first device according to the invention.

[0271] A filling opening 62 for the introduction of bone cement paste 50 may be formed on one side of the casting mold 61, which filling opening may be defined in each case in both parts of the stem mold 94 by a semicircular cylindrical opening. This filling opening 62 may form a valve seat 63 which may be embodied as part of the stem mold 94. The valve seat 63 may be firmly connected to the casting mold 61. The mold cavity 92 and thus the spherical surface-shaped inner surface of the mold cavity can be continuously expanded by injecting the bone cement paste 50 into the casting mold 61. The diameter of the head of a spacer fabricated with the device may consequently be variably adjusted.

[0272] The valve seat 63 may take the form of a hollow cylinder which, apart from two first feed-throughs 65, is closed on a head side 64 oriented in the direction of the filling opening 62. The two first feed-throughs 65 may be quadrant-shaped and may preferably be arranged rotated relative to one another by 180° with regard to the cylinder axis of the valve seat 63. A valve body 66 may be arranged in the interior of the valve seat 63 so as to be axially rotatable relative to the valve seat 63. The valve body 66 may have a sealing face 67 or surface oriented in the direction of the head side 64 of the valve seat 63. The valve body 66 may be constructed as a stepped hollow cylinder, the front part of which can be screwed or put into the valve seat 63.

[0273] Two second feed-throughs 68 may be arranged in the sealing face 67. The two second feed-throughs 68 may, similarly to the first feed-throughs 65, be quadrant-shaped and may preferably be arranged rotated or offset relative to one another by 180° with regard to the cylinder axis of the valve body 66. The valve seat 63 and valve body 66 together form a valve of the device. An adapter element 69 for liquid-tight connection of a bone cement cartridge 10 may be screwed into the valve body 66 (see FIG. 16). The bone cement cartridge 10 and the adapter element 69 may be part of the device according to the invention. The valve body 66 may on its open side, which is remote from the sealing face 67, be formed as a port 71 for connecting the adapter element 69. The same bone cement cartridge 10 as described in the first exemplary embodiment described may be used to fill the casting mold 61 with bone cement paste 50. The same reference signs are therefore used for both embodiments.

[0274] The bone cement cartridge 10 may have on its front side a delivery tube 37 with a delivery opening 12 for delivering the bone cement paste 50 from the bone cement cartridge 10. The delivery opening 12 may be arranged together with the delivery tube 37 in the adapter element 9 and be delimited by the delivery tube 37. The adapter element 9 may close the bone cement cartridge 10 on its front side apart from the delivery opening 12 and optionally apart from a vacuum port 104. Sealing may be provided by arranging in the adapter element 9 a seal 73 in the form of an O-ring of rubber, which seals against the delivery tube 37. A mixer 36 with a plurality of mixing blades, with which the bone cement paste 50 can be mixed in the interior of the bone cement cartridge 10, may be fastened at the end of the delivery tube 37 pointing into the interior of the bone cement cartridge 10 before the bone cement cartridge 10 is connected to the valve. The delivery tube 37 may to this end be mounted in axially linearly and rotatably mobile manner in the adapter element 9.

[0275] The mold cavity 92 may consist of a rubber-elastic plastics material. As a result, the mold cavity 92 can be expanded with the assistance of the bone cement paste 50, as is visible in FIGS. 17, 18 and 19. FIG. 17 here shows an unexpanded mold cavity 92, FIG. 18 dimensions for additional possible expanded mold cavities 92 as dashed lines and FIG. 19 an expanded mold cavity 92. The wall thickness of the mold cavity 92 is uniform, such that the mold cavity 92 expands uniformly when a pressure is exerted in the interior of the mold cavity 92 via the bone cement paste 50.

[0276] The stem mold 94 and the adapter element 102 may be inexpensively fabricated from plastics film and are dimensionally stable, such that, in contrast to the mold cavity 92, they cannot or cannot substantially be expanded by a pressure exerted by the bone cement paste 50 in the interior of the casting mold 61. The plastics film may have a plurality of layers. The two parts of the stem mold 94 may be fastened flush together via flanges 74. The mold cavity 92 and the adapter element 102 may likewise be connected flush together via a flange 95 of the adapter element 102 and an annular disk 83 of the mold cavity 92. By connecting the parts of the casting mold 61 via the flanges 74, 95 and the annular disk 83 and via the inner thread 103 and outer thread 107, the casting mold 61 may be closed to the outside. The annular disk 83 may be screwed via a segmented annular mount 81 to the flange 95. Screws 85 may to this end be screwed into fittings 87 having inner threads which match the screws 85. The two parts of the stem mold 94 may likewise be fastened together with screws 91 which are screwed into fittings 93 having inner threads which match the screws 91. In order to simplify positioning of the two parts of the stem mold 94 relative to one another and of the mold cavity 92 on the flange 95 of the adapter element 102, pins 89 may be provided which can be put into recesses 99 on the opposing flange 74 or flange 95. The annular disk 83 seals the connection of the mold cavity 92 to the adapter element 102 in the manner of a sealing ring.

[0277] At least one vent element 75 having in each case at least one vent opening 79 may be arranged in the casting mold 61. At least one vent element 75 may be arranged in the mold cavity 92 so that it is possible to expel air from the interior of the casting mold 61. Air or gas can escape through the vent opening 79 from the interior of the closed casting mold 61 when a bone cement paste 50 is filled into the casting mold 61 through the filling opening 62. A porous filter 77 which is permeable to gases but impermeable to the bone cement paste 50 can be arranged in the vent element 75. In this way, the bone cement paste 50 is prevented from being able to escape through the vent opening 79 during filling of the casting mold 61 and consequently on the one hand impairing the shape of the head of the spacer and on the other hand allowing the pressure of the bone cement paste 50 in the mold cavity 92 to decline by outflow of bone cement paste 50 from the mold cavity 92. This ensures that the mold cavity 92 remains in the desired expanded state while the bone cement paste 50 begins to cure in the casting mold 61. It may be sufficient for the free cross-sectional area of the vent opening 79 to be so small that the bone cement paste 50 cannot escape through the vent opening 79 due to its viscid consistency.

[0278] A metal core 76 may be placed in the interior of the casting mold 61. The metal core 76 may consist of surgical steel or of titanium. Alternatively, it would theoretically also be possible to fabricate the metal core 76 from a plastics material such as PMMA. The metal core 76 may be connected to the stem mold 94 via retaining pins 78. The metal core 76 may be spaced from the internal wall of the casting mold 61 with the aid of the retaining pins 78, such that the bone cement paste 50 can flow right around the metal core 76. The metal core 76 brings about stabilization of the spacer 120, 130. The retaining pins 78 may consist of PMMA. This can irreversibly bond to a bone cement paste 50 of PMMA.

[0279] The valve seat 63 may have an inner thread 80 on its inside. On the front half of the valve body 66 facing the sealing face 67, the valve body 66 may have on the outside thereof an outer thread 82 matching the inner thread 80 of the valve seat 63. The valve body 66 may be screwed with its outer thread 82 into the inner thread 80 of the valve seat 63.

[0280] The first feed-throughs 65 and the second feed-throughs 68 may be brought into overlap with one another by screwing the valve body 66 into the valve seat 63 until the limit stop is reached. The valve is then in the open state. In this open state, a bone cement paste 50 may flow through the first feed-throughs 65 and through the second feed-throughs 68 out of the bone cement cartridge 10 into the casting mold 61. By making a quarter rotation (by 90°) of the valve body 66 relative to the valve seat 63, i.e. by unscrewing the valve body 66 from the valve seat 63, the first feed-throughs 65 and the second feed-throughs 68 may be offset relative to one another, such that the sealing face 67 of the valve body 66 covers the first feed-throughs 65 of the valve seat 63 and the closed regions of the head side 64 of the valve seat 63 cover the second feed-throughs 68 of the valve body 66. The valve is then in the closed state. Due to the small stroke of the valve body 66 relative to the valve seat 63 in the event of a quarter rotation, the gap arising between the valve body 66 and the valve seat 63 is so narrow (less than 1 mm wide) that a bone cement paste 50 of a normal, let alone high, viscosity, is incapable of passing through the gap. This is particularly the case because the bone cement paste 50 is deflected from its actual direction of flow by 90° in the gap.

[0281] The reverse side of the valve body 66 may have an inner thread 84 arranged in the port 71. The adapter element 69 has on its front side an outer thread 86 which matches the inner thread 84. The adapter element 69 may accordingly be screwed into the port 71 of the valve body 66. In this way, a liquid-tight connection can be created between the bone cement cartridge 10 and the valve body 66 and thus into the casting mold 61. The inner thread 80 of the valve seat 63, the outer thread 82 of the valve body 66, the inner thread 84 of the valve body 66 and the outer thread 86 of the adapter element 69 may all have the same direction of rotation, i.e. all these threads are right-hand threads or left-hand threads. As a result, the valve can be opened by screwing the adapter element 69 into the port 71 and continuing to rotate the adapter element 69 in the same direction. At the same time, the valve body 66 also provides a seal relative to the valve seat 63.

[0282] The adapter element 69 may be or have been connected via a latching means 88 on the adapter element 69 to a mating latch 30 on a cylindrical wall of the bone cement cartridge 10. A circumferential seal 48 which seals the cylindrical wall of the bone cement cartridge 10 relative to the adapter element 69 may be provided for sealing.

[0283] The casting mold 61 may include the mold cavity 92 for forming the joint head (head) of the spacer and the stem mold 94 for forming the stem of a spacer. The adapter element 102 may be considered to be part of the stem mold 94. The stem mold is then in three parts. Moreover, an orifice for a lever of the valve body 66 may be arranged in the casting mold 91 in the region of the filling opening 92. The lever may be connected to the valve body 66. The valve body 66 can be rotated in the valve seat 63 with the lever. The orifice is preferably precisely large enough for the valve body 66 to be rotatable only by a maximum of a quarter rotation relative to the valve seat 63. As a result, with the assistance of the lever, the valve can be transferred manually from outside from the open state into the closed state or from the closed state into the open state.

[0284] In the region of the flanges 74, shapes 100 may be arranged in the stem mold 94 for cavities, in which shapes the retaining pins 78 may be arranged.

[0285] A vacuum port 104 which is capable of evacuating an interior of the bone cement cartridge 10 in which the bone cement paste 50 is mixed may be arranged in the adapter element 69. As a result, the bone cement paste 50 can be mixed under a vacuum.

[0286] A piston 46 for discharging the bone cement paste 50 from the bone cement cartridge 10 through the valve into the casting mold 61 may be arranged in the cylindrical interior of the bone cement cartridge 10. The piston 46 may to this end be cylindrically shaped on the outside and be sealed relative to the cylindrical interior via two circumferential seals 47. By advancing the piston 46, the bone cement paste 50 can be pressed out of the delivery opening 12 of the bone cement cartridge 10 into or through the open valve.

[0287] A porous disk 52 may be arranged in the adapter element 69. The porous disk 52 is impermeable to the bone cement paste 50 and its starting components. The vacuum port 104 can be covered by the porous disk 52. This prevents any bone cement powder as a starting component of the bone cement paste 50 from being able to penetrate into the vacuum port 104.

[0288] The course of a method according to the invention is shown in FIGS. 12 to 21 with reference to the second device according to the invention. First of all, the metal core 76 may be positioned with the retaining pins 78 in the stem mold 94. To this end, the retaining pins 78 may be arranged and retained at one end between the two parts of the stem mold 94 in the cavities formed by the shapes 100 and arranged with the other end in matching bores in the metal core 76. In order to fasten the two parts of the stem mold 94 together, the flanges 74 of the two parts of the stem mold 94 can firstly be positioned via the pins 79 in the recesses 99 and then the two parts of the stem mold 94 to be joined together via the flange 74 can be screwed together with the assistance of the screws 91. The adapter element 102 may then be screwed onto the fitting 105. The adapter element 102 may here be screwed onto the fitting 105 to such an extent that the desired length of the neck is obtained. Markings (not shown), from which the length of the neck of the spacer to be produced with the device can be read off, may to this end be arranged on the outside of the adapter element 102. The casting mold 61 may then be closed by fastening the mold cavity 92 to the adapter element 102. The annular disk 83 may to this end be laid on the flange 95. The two half rings of the mount 81 can then be laid on the annular disk 83 and positioned via the pins 89 and the recesses 99. The mold cavity 92 can then be fastened to the adapter element 102 by tightening the screws 85, wherein the annular disk 83 seals the connection. The casting mold 61 is then closed with the metal core 76 therein and can be provided to mold a spacer. This situation is shown in FIG. 15.

[0289] A bone cement paste 50 can be mixed under a vacuum in the bone cement cartridge 10. The bone cement cartridge 10 can then be screwed with the adapter element 69 into the port 71 of the valve body 66. On screwing in the adapter element 69, the valve can be transferred into the open position by screwing the valve body 66 into the valve seat 63 until the limit stop is reached.

[0290] The bone cement paste 50 is then pressed out of the bone cement cartridge 10 through the valve and through the overlapping first feed-throughs 65 and second feed-throughs 68 into the casting mold 61 by advancing the piston 46. This situation is shown in FIG. 16. By closing the valve by rotating the valve body 66 by a quarter rotation relative to the valve seat 63, a new bone cement cartridge 10 can be attached at intervals if the volume of the bone cement paste 50 from a single bone cement cartridge 10 is not enough to fill the casting mold 61 completely. The bone cement paste 50 contained in the casting mold 61 cannot flow back out again since the first passages 65 and the second passages 68 are covered in the closed position of the valve and the gap therebetween is insufficient for the viscous bone cement paste 50 to be able flow through. Simultaneously, pressure from the bone cement paste 50 is maintained in the interior of the mold cavity 92 by the closed valve.

[0291] At some point, the casting mold 61 is filled with the bone cement paste 50. Air or gas has escaped from the casting mold 1 through vent openings in the casting mold 61. This situation is shown in FIG. 16. Air or gas can escape from the casting mold 61 through the vent element 75 or through the vent openings 79 in the mold cavity 92. The mold cavity 92 can be expanded to the desired size by further injection of bone cement paste 50 (see FIGS. 18 and 19 in comparison with FIG. 17). Radial expansion can be determined with the assistance of a check gage or a vernier caliper (not shown) for measuring the current diameter of the mold cavity 92. Since the wall thickness of the mold cavity 92 is known, the current diameter of the spherical surface-shaped inner surface of the mold cavity 92 is also determinable. Alternatively or additionally, a dimensionally stable mating mold (not shown) with a known and defined diameter may be provided into which the mold cavity 92 can be laid, such that the mold cavity 92 can only expand until it rests against the mating mold. In this way, the desired diameter of the head of the spacer produced with the device can be straightforwardly established. Once the desired radial expansion of the spherical surface-shaped inner surface of the mold cavity 92 has been reached, the valve can be closed.

[0292] By closing the valve, the bone cement paste 50 is sheared or cut off The bone cement cartridge 10 can be unscrewed and removed. Any remaining thin connections simply tear or break away. This situation is shown in FIGS. 17 and 19.

[0293] In this state, the bone cement paste 50 can be cured in the casting mold 61. This situation is shown in FIG. 19. The size or diameter of the head of the spacer here matches the diameter of the spherical surface-shaped inner surface of the expanded mold cavity 92. In order to avoid unevenness of the sliding surface of the spacer, it is preferred according to the invention that, even when producing spacers with heads having the smallest diameter, the mold cavity 92 is already slightly expanded such that the bone cement paste 50 is under pressure in the casting mold 61 while it cures.

[0294] Then, the spacer 120, 130 (see FIGS. 20 and 21) formed in this way is removed from the casting mold 1. The projecting retaining pins 78 may be cut off. Any sprue caused by the valve seat 63 and the first passages 65 can likewise be cut off and removed. Points caused by the vent openings may also be removed. This situation is shown in FIGS. 20 and 21.

[0295] FIG. 20 shows the removed spacer 120. The spacer 120 has a head 122 which has been shaped by the mold cavity 92. The spacer 120 was shaped by curing the bone cement paste 50 in the casting mold 61, as shown in FIG. 17. The head 122 is connected via a neck 126 to a stem 124 of the spacer 120.

[0296] FIG. 21 shows an alternative spacer 130 with a longer neck 136 which has been molded by extension with the adapter element 102 (see FIGS. 18 and 19). The spacer 130 has a head 132 which has been shaped by the mold cavity 92. The spacer 130 was shaped by curing the bone cement paste 50 in the casting mold 61, as shown in FIG. 18. The head 132 is connected via the neck 136 to a stem 134 of the spacer 130. In its proximal region, the neck 134 has the shape of a thread since it is a negative shape of the inner thread 103 of the adapter element 102. If required, the surface in this region can be smoothed.

[0297] The surface of the spacer 120, 130 can be polished and/or coated, for example with antibiotics.

[0298] Instead of a casting mold 61 for molding a shoulder joint spacer, it is also straightforwardly possible to use a casting mold for molding a different spacer.

[0299] FIGS. 22 to 28 show a valve for a device according to the invention for producing a spacer in the open position (FIGS. 22 to 24) and in the closed position (FIGS. 25 to 28). The valve corresponds to the valves of the first device according to the invention according to FIGS. 1 to 11 and of the second device according to the invention according to FIGS. 12 to 19, but may also be used with other casting molds to produce other spacers.

[0300] The valve has a valve seat 163, which may be arranged in a filling opening of a casting mold (not shown). The valve seat 163 may be firmly connected to a part of the casting mold or have been made in one piece with the casting mold. For better and tighter connectability of the valve seat 163 to a casting mold, the valve seat 163 may have patterning on its external surface, for example longitudinal grooves, which are arranged parallel to the cylinder axis of a cylindrical outer wall of the valve seat 163.

[0301] The valve seat 163 may take the form of a hollow cylinder which, apart from two first feed-throughs 165, is closed on a head side 164. The two first feed-throughs 165 may be quadrant-shaped and may preferably be arranged rotated relative to one another by 180° with regard to the cylinder axis of the valve seat 163. A valve body 166 may be arranged in the interior of the valve seat 163 so as to be axially rotatable relative to the valve seat 163. The valve body 166 may have a sealing face 167 or surface oriented in the direction of the head side 164 of the valve seat 163. The valve body 166 may be constructed as a stepped hollow cylinder, the front part of which can be screwed or put into the valve seat 163.

[0302] Two second feed-throughs 168 may be arranged in the sealing face 167. The two second feed-throughs 168 may, similarly to the first feed-throughs 165, be quadrant-shaped and may preferably be arranged rotated or offset relative to one another by 180° with regard to the cylinder axis of the valve body 166. The valve seat 163 and valve body 166 together form the valve of a device according to the invention. An adapter element (not shown) for liquid-tight connection of a bone cement cartridge (not shown) may be screwed into the valve body 166. The valve body 166 may on its open side, which is remote from the sealing face 167, be formed as a port 171 for connecting an adapter element.

[0303] The valve seat 163 may have an inner thread 180 on its inside. On the front half of the valve body 166 facing the sealing face 167, the valve body 166 may have on the outside thereof an outer thread 182 matching the inner thread 180 of the valve seat 163. The valve body 166 may be screwed with its outer thread 182 into the inner thread 180 of the valve seat 163.

[0304] The first feed-throughs 165 and the second feed-throughs 168 may be brought into overlap with one another by screwing the valve body 166 into the valve seat 163 until the limit stop is reached. The valve is then in the open state. In this open state (see FIGS. 22 to 24), a bone cement paste may flow through the first feed-throughs 165 and through the second feed-throughs 168. By making a quarter rotation (by 90°) of the valve body 166 relative to the valve seat 163, i.e. by unscrewing the valve body 166 from the valve seat 163, the first feed-throughs 165 and the second feed-throughs 168 may be offset relative to one another, such that the sealing face 167 of the valve body 166 covers the first feed-throughs 165 of the valve seat 163 and the closed regions of the head side 164 of the valve seat 163 cover the second feed-throughs 168 of the valve body 166. The valve is then in the closed state (see FIGS. 25 to 28). Due to the small stroke of the valve body 166 relative to the valve seat 163 in the event of a quarter rotation, the gap 220 arising between the valve body 166 and the valve seat 163 is so narrow (less than 1 mm wide) that a bone cement paste of a normal, let alone high, viscosity, is incapable of passing through the gap 220 (see FIG. 28). This is particularly the case because the bone cement paste is deflected from its actual direction of flow by 90° in the gap 220. A projection 216 may be provided in order to ensure more stable, non-rotatable connection of the valve seat 163 to the casting mold.

[0305] The reverse side of the valve body 166 may have an inner thread 184 arranged in the port 171. An adapter element (not shown) may accordingly be screwed into the port 171 of the valve body 166. The inner thread 180 of the valve seat 163, the outer thread 182 of the valve body 166 and the inner thread 184 of the valve body 166 may all have the same direction of rotation, i.e. all these threads are right-hand threads or left-hand threads. As a result, the valve can be opened by screwing an adapter element into the port 171 and continuing to rotate the adapter element in the same direction. At the same time, the valve body 166 also provides a seal relative to the valve seat 163.

[0306] Furthermore, a lever 198 may be arranged on the valve body 166. The valve body 166 can be rotated in the valve seat 163 with the lever 198. As a result, with the assistance of the lever 198, the valve can be transferred manually from outside from the open state into the closed state or from the closed state into the open state.

[0307] The features of the invention disclosed in the preceding description, as well as in the claims, figures and exemplary embodiments, may be essential both individually and in any combination for realizing the invention in its various embodiments.

LIST OF REFERENCE NUMERALS

[0308] 1, 61 Casting mold [0309] 2, 62 Filling opening [0310] 3, 63, 163 Valve seat [0311] 4, 64, 164 Head side [0312] 5, 65, 165 Feed-through [0313] 6, 66, 166 Valve body [0314] 7, 67, 167 Sealing face [0315] 8, 68, 168 Feed-through [0316] 9, 69 Adapter element [0317] 10 Bone cement cartridge [0318] 11, 71, 171 Port [0319] 12 Delivery opening [0320] 13, 73 Seal [0321] 14, 74 Flange [0322] 15, 75 Vent element [0323] 16, 76 Metal core [0324] 17, 77 Porous filter [0325] 18, 78 Retaining pin [0326] 19, 79 Vent opening [0327] 20, 80, 180 Inner thread [0328] 21, 81 Mount [0329] 22, 82, 182 Outer thread [0330] 23, 83 Annular disk [0331] 24, 84, 184 Inner thread [0332] 25, 85 Screw [0333] 26, 86 Outer thread [0334] 27, 87 Fitting [0335] 28, 88 Latching means [0336] 29, 89 Pin [0337] 30 Mating latch [0338] 31, 91 Screw [0339] 32, 92 Mold cavity [0340] 33, 93 Fitting [0341] 34, 94 Stem mold [0342] 35, 95 Flange [0343] 36 Mixer [0344] 37 Delivery tube [0345] 38 Lever [0346] 39, 99′ Recess [0347] 40, 100 Shape for cavities [0348] 44, 104 Vacuum port [0349] 46 Piston [0350] 47 Seal [0351] 48 Seal [0352] 50 Bone cement paste [0353] 52 Porous disk [0354] 102 Adapter element [0355] 103 Internal thread [0356] 105 Hollow cylinder [0357] 107 Outer thread [0358] 120, 130 Spacer [0359] 122, 132 Head [0360] 124, 134 Stem [0361] 126, 136 Neck [0362] 216 Projection [0363] 220 Gap