Devices, methods, and uses for determining distance

Abstract

The present invention provides a device, system, and method for manufacturing a joint spacer for determining the required distance between the head region and the shaft region of a joint spacer. [Solution] A device for determining the required distance between the shaft region 3 and the head region 2 of a joint spacer 1 comprises a head and a shaft that can be positioned at different distances from each other, and the device further comprises a fixing device for fixing the distance between the head and the shaft. The device makes it possible to determine the required shape of the hip joint spacer intraoperatively by adjusting the distance from the shaft to the head relative to the patient's specific anatomical structure.

Description

Technical Field

[0001] The present invention relates to a device, system, method of manufacturing an articular spacer, and use for determining the necessary distance between the head region and the shaft region of an articular spacer. Preferably, the device is also designed to combine any head with any shaft in order to obtain an articular spacer optimally adapted to the patient's anatomical structure.

[0002] In the context of two-stage replacement of artificial joints, such as total hip or shoulder arthroplasty, a spacer is used as a temporary space-holding member (placeholder) during the intermediate period. This spacer is used particularly in septic replacement operations. Such spacers are often manufactured by medical personnel during the operation from bone cement, such as polymethylmethacrylate bone cement. At the time of manufacturing these spacers, one or more antibiotics specifically prepared for the existing bacteria can be added to the bone cement according to the available antimicrobial susceptibility test of the bacteria causing the infection.

[0003] There are already off-the-shelf spacers that provide excellent stability but are not adapted to the individual anatomical structure of the patient. Therefore, it is preferred that the individual spacer be manufactured during the operation.

[0004] In the intraoperative manufacture of spacers using conventional bone cement, plastic molds are generally used, as described, for example, in US Patent No. 6361731 (B1). These molds can be manufactured using different diameters of spacer heads. In this case, the medical user can select between predetermined sizes of spacer heads. In this way, a customized spacer can be provided to the patient according to a specific anatomical situation. The spacer for a joint or joint site is called an articular spacer.

[0005] In more advanced forms, U.S. Patents 7,637,729(B2), 7,789,646(B2), 8,480,389(B2), and 880,1983(B2) propose multi-part molds for the manufacture of modular hip spacers. The molds in U.S. Patents 7,789,646(B2), 8,480,389(B2), and 880,1983(B2) consist of a mold for a shaft that can be connected to a mold for a spacer head. Molds for spacer heads with different diameters are available. The shaft mold is connected to a spacer head mold of the selected diameter. The mold thus assembled can then be filled with bone cement. After hardening, the formed hip spacer is removed.

[0006] European Patent No. 3957280(B1) describes a device for manufacturing hip joint spacers that enables the production of patient-specific hip joint spacers with respect to the size of the spacer head and the distance of the head from the femoral shaft (femoral offset). This allows for further adjustment of the spacer.

[0007] The objective of the present invention is to easily and reproducibly determine the required shape of a joint spacer in order to improve the manufacture of individually tailored joint spacers.

[0008] This objective is achieved by the device described in claim 1, and by the systems, methods, and uses described in the related claims. Advantageous embodiments can be found in the dependent claims.

[0009] To achieve this objective, a device is used to determine the required distance between the head region and the shaft region of a joint spacer. This device comprises a head and a shaft that can be positioned at different distances from each other. This device further comprises a fixing device for fixing the distance between the head and the shaft.

[0010] This device is designed to be temporarily inserted into a patient's body at the location where a spacer will be inserted, in order to determine the required distance between the head region and the shaft region of the spacer, or to determine whether the selected distance is suitable for specific anatomical conditions. The device is designed to fix the selected distance between the head and shaft, thereby preventing the possibility of unexpected separation of the shaft and head, which could lead to unexpected changes in the distance or loss of the head. In particular, this distance is fixed during use in the patient's body. This device may also be called a test gauge.

[0011] The device allows for the determination of the required shape of the hip spacer during surgery by adjusting the distance from the shaft to the head (also known as the "femoral offset") relative to the patient's specific anatomical structure. This means that the correct spacer can be individually selected for each patient. For example, the spacer can be manufactured during surgery using a hip spacer mold and / or in accordance with European Patent No. 3957280(B1).

[0012] The manufactured and inserted spacer comprises a head region (head), a shaft region (shaft), and, optionally, an intermediate neck region (neck) connecting the head region and the shaft region. The spacer is modeled based on the shape and size of a corresponding bone, such as the femur (thigh bone), particularly in its head region. The shaft region of the spacer is inserted into an opening in the bone and typically fixed therein. The head region of the spacer is substantially spherical in at least some areas to replicate a movable connection with, for example, the pelvis, in this case the hip joint. The spacer may further include a neck region connecting the shaft to the head.

[0013] The device head is also shaped similarly to the head of the corresponding joint, for example, the head of the femur. The head may have a substantially spherical outer surface in at least some areas. The head may be partially or completely hollow. The device shaft is designed to be inserted into an opening in the bone. For example, the shaft is elongated and tapered in cross-section to facilitate insertion.

[0014] The head and shaft are typically movable relative to each other, and particularly linearly displaceable, to be positioned at different distances. A fixing device secures the head to the shaft directly or indirectly. In the locked (fixed) state, the head and shaft are connected by a neck in between, which, if necessary, prevents relative movement between the head and shaft that changes the distance. This could be, for example, axial movement along the longitudinal axis of the shaft, or axial movement along the neck located between the shaft and the head. The longitudinal axis specifically refers to the central longitudinal axis.

[0015] In a simple embodiment, the shaft and the head are connected by screw threads. For example, the shaft or the neck connected to the shaft has a male thread, and the head has a female thread. Thus, the axial position of the head relative to the shaft can be adjusted by relative rotation.

[0016] The fixing device may include, for example, a pin designed to be retractable, so as to fix the position of the head relative to the shaft. For this purpose, the pin may be moved, for example, into a suitable receiving part. Alternatively or additionally, the fixing device may include a locking element that can be pre-tensioned by a spring. In this way, when the head is locked and fixed by the spring, movement between the head and the shaft can be prevented. Movement between the head and the shaft can be released when the locking element is released against the spring force, for example by manually pushing it. Movement may be possible only when the locking element is pressed.

[0017] In one embodiment, the device further comprises a neck connecting the head to the shaft. The neck is securely connected to the shaft in particular. The neck can be integrated with the shaft. In particular, the head is designed to be pressed into or screwed into the neck and / or fixed to the neck.

[0018] In particular, the neck is designed to allow for different distances between the shaft and the head. For example, the head can be positioned at different locations on the neck.

[0019] The neck may form an angle other than 180° with the shaft. In the femoral region, this angle may correspond to the CCD angle (head-neck diaphysis angle). This angle may be at least 100°, preferably at least 110°, particularly at least 120°, and / or up to 160°, preferably up to 150°, particularly up to 140°. This design allows for the manufacture of a particularly well-fitted spacer that is optimally suited to the patient's anatomical structure.

[0020] In one embodiment, the head on one side and the shaft and / or neck on the other side are separated from each other, or can be separated from each other.

[0021] In this embodiment, the shaft and head may be indirectly connected to each other via a neck, and subsequently fixed to each other in a desired position by a fixing device. This makes it possible to replace the head or shaft, or to specifically select different combinations of shafts and heads. For example, a desired head size that best fits the patient's anatomical structure can be selected. Alternatively or additionally, a shaft of a specific length and / or diameter that best fits the patient's anatomical structure can be selected.

[0022] In one embodiment, the head is displaceable on the neck. The locking device comprises at least one pin and a plurality of shape locking elements. The pin can be in contact with one or two shape locking elements to prevent the head from being displaced on the neck.

[0023] The pin is located on one of the two displaceable parts relative to each other, particularly on the head. The shape locking element is located on the other of the two displaceable parts relative to each other, particularly on the neck. In particular, the head is displaceable on the neck along the axial direction with respect to the longitudinal axis of the neck. The longitudinal axis of the neck may correspond to the axis of symmetry and / or the longitudinal axis of the head. In particular, the axial position of the head on the neck is fixed.

[0024] A pin is an element that protrudes from its surroundings. A pin can have a circular or square cross-section, or even an elongated or rectangular cross-section. In principle, a pin can be of any shape. To prevent displacement, it is only necessary to ensure the pin is in proper contact with the shape-locking element. In particular, the pins are aligned at least substantially radially.

[0025] The pin can typically be made to contact one of the shape-locking elements. These shape-locking elements are typically positioned at different locations relative to the longitudinal axis of the element having the shape-locking element, particularly in a single line. By selecting which shape-locking element to contact the pin, the relative position, and therefore distance, between the head and the neck is fixed. The shape-locking elements are particularly aligned circumferentially.

[0026] In principle, it is sufficient for the pin to contact one shape-locking element to prevent displacement in one direction. Preferably, the pin can be positioned between two shape-locking elements to prevent displacement in both directions. In particular, in either case, there is a gap between two adjacent shape-locking elements, and the pin can be positioned within this gap to fix its distance.

[0027] As a principle, there are at least three shape locking elements and two gaps therebetween, as a result of which two different distances can be set depending on the selection of the gaps. In particular, there are at least four or five, or more shape locking elements.

[0028] In particular, there are two pins axially spaced from each other. Typically, these two pins are on an imaginary line extending axially. The axial direction refers to the component having the pins. In this way, jamming is reliably prevented. There may be two sets of shape locking elements and the gaps therebetween. Each pin can engage with one set of shape locking elements.

[0029] In one embodiment, axially aligned grooves are arranged adjacent to the plurality of shape locking elements. The pins can be displaced axially within the grooves. Thereby, the distance can be set.

[0030] In this case, the shape locking elements are particularly comb-shaped. The axially aligned grooves adjacent to the shape locking elements are particularly used to displace the head on the neck. In particular, the pins arranged on the head can slide within the grooves while the head is displaced axially on the neck. In a plan view, the gaps and / or the shape locking elements are arranged perpendicular to the grooves.

[0031] In particular, by rotating the head relative to the neck about the axial axis, an engagement can be achieved in which the pins are arranged between two shape locking elements and axial displacement is prevented. Therefore, after setting the desired distance, the set distance can be fixed by relative rotation of the head with respect to the neck.

[0032] In particular, the grooves are arranged at an adjacent angular position of the component with respect to the shape locking elements or the gaps therebetween with respect to the circumferential surface of the component having the grooves. In particular, the grooves are directly connected to each of the gaps, as a result of which, during relative rotation, the pins can move from the grooves into one of the gaps and thus the distance can be fixed.

[0033] In one embodiment, the fixing device includes a switching device for switching from an open position to a closed position. In particular, the distance between the head and the shaft can be changed in the open position and / or the distance between the head and the shaft is fixed in the closed position.

[0034] Therefore, a desired distance can be set in the open position. Then, a switch can be performed to fix the desired distance. In particular, the switching device is also designed to return from the closed position to the open position. Preferably, the switching can be performed by moving back and forth between the two positions several times. In this way, the desired distance can be determined in several iterations.

[0035] The switching device can be operated manually. Preferably, the switching device is a mechanical switching device. In this case, no electrical or electronic components are required for switching.

[0036] In principle, switching can be performed by moving one component of a device relative to another component of the device, for example, by moving the switch relative to the housing. This movement may be linear and / or rotational.

[0037] Changing the distance between the head and the shaft in the open position does not necessarily have to be done simply by displacing the head. For example, rotation may be required before displacement in order to disengage a pin from one or more shape locking elements. Movement between the head and the shaft is possible, especially in the open position.

[0038] This embodiment prevents undesirable displacement of the head relative to the neck and loosening of the head while testing possible shapes of the spacer using the device within a patient.

[0039] In one embodiment, the device includes a scale for reading the distance between the head and the shaft. The scale may be positioned in the area of ​​a shape locking element, so that the position of the pin indicates the position or distance on the scale.

[0040] In one embodiment, switching is performed by rotating a rotating unit around the longitudinal axis of the neck relative to the housing portion. The rotating unit is a unit mounted to be rotatable. In particular, switching to other positions can therefore be performed, for example, by rotating it again in the opposite direction.

[0041] In particular, the neck has a housing. The housing may define the outer shell of the neck. The housing is a transition between a head, for example, a different head, and a shaft, for example, a different shaft, and may therefore also be called an adapter. In particular, the rotating unit is rotatable relative to the entire housing.

[0042] In one embodiment, a locking element is provided that is activated when switching to the closed position and prevents any movement between the head and the shaft. In this embodiment, both axial displacement and rotation between the head and the neck are prevented in the closed position. In this way, accidental release can also be prevented. Therefore, in the closed position, movement between the head and the shaft is impossible.

[0043] When switching is performed by the rotation of a rotary unit relative to the housing portion, and the rotary unit is rotatable relative to the housing portion about the longitudinal axis of the neck, the locking element may be part of the rotary unit. Therefore, the locking element can be easily operated and deactivated by rotation. The locking element is, in particular, part of the switching device.

[0044] In the closed position, the locking element can prevent the pin from circumferentially protruding from the gap between the two shape locking elements. This prevents rotation of the rotating unit in the neck or neck housing. The locking element may be an axially extending web. A radially oriented axial groove or recess may exist next to the web, as a result allowing the pin to protrude from the gap in the open position.

[0045] For example, the neck housing may have a window-like opening through which the locking element can be moved, for example, rotated, from a recessed or open position to a closed position.

[0046] For example, after setting and fixing the desired distance as described above, the locking element can be activated to secure the desired distance.

[0047] In one embodiment, the locking element is connected to a spring-loaded button that interacts with two recesses. The button is positioned within the first recess when the locking device is in the closed position. The button is positioned within the second recess when the locking device is in the open position.

[0048] Therefore, the position of the button indicates either the closed or open position. The button is located particularly on the rotating unit. The recess is located particularly on the housing portion. The button is typically fixed within the recess in such a way that it cannot be switched, for example, by a shape lock. In particular, rotation of the rotating unit relative to the housing portion is impossible because the button is located within the recess in such a way that rotation of the rotating unit relative to the housing portion is prevented. For switching, the button can be pushed radially inward against a spring force so that it sinks beneath the material forming the recess. In this position, the rotatable portion can be rotated relative to the housing portion. When the button is located beneath the other recess, the button is pushed radially outward by a spring force, thereby snapping into the other recess. At this point, the devices are in their respective other positions.

[0049] The two recesses are particularly window-like and may therefore be called windows. The two recesses may be connected. Thus, there may be two different defined regions of a single recess, which, according to the present invention, are referred to as two recesses. In particular, the two recesses are positioned at different angular positions with respect to the longitudinal axis. In particular, the two recesses are positioned at the same length with respect to the longitudinal axis.

[0050] The button is part of the locking element and is securely connected to it. Therefore, the locking element and the button rotate together around the longitudinal axis. Specifically, the button is mounted on a leaf spring and has an outward preload. For example, visual symbols can be placed next to the recesses to indicate each position (open / closed), thereby allowing the current position to be directly seen from the button's position.

[0051] In one embodiment, the fixing device further comprises at least one additional pin located at a position rotated 180° around the longitudinal axis, starting from the pin. Alternatively or additionally, the fixing device further comprises a further plurality of shape locking elements located at a position rotated 180° around the longitudinal axis, starting from the plurality of shape locking elements.

[0052] Therefore, fixing against axial movement is performed at two opposing positions. This prevents tilting with respect to the longitudinal axis and ensures secure fixation. To prevent tilting perpendicular to the longitudinal axis, two webs and two sets of shape locking elements may be present at each angular position.

[0053] In one embodiment, the device has an outer shell in the head and / or shaft region that defines a cavity to the outside. In particular, a filling opening for filling the cavity with bone cement is located in the outer shell.

[0054] The outer shell is typically not completely hollow. Cavities extend, in particular, between the outer shell and the core of the head or shaft device, which may be made of metal, for example. The core may function to stabilize and / or secure the device. In particular, the head and / or shaft are at least partially hollow. The neck may also be partially hollow. The device may include additional metal reinforcement in the shaft and / or neck.

[0055] The filling opening is used to fill with bone cement. The filling opening is typically designed to accommodate any filler material. The bone cement can then harden inside the device, thus forming a rigid and stable spacer.

[0056] In particular, in this case, the device can function as a disappearing type. The outer shell then remains on the bone cement, and this outer shell, along with possibly one or more metal cores, forms a spacer. This allows for the direct fabrication of a dimensionally stable spacer from the device. Typically, there is at least one filling opening in the head and at least one filling opening in the shaft.

[0057] It is particularly preferable that at least the outer shell of the device is made of polymethyl methacrylate. There may be a passage at the end of the neck facing the shaft, through which the bone cement filled in the shaft can flow into the interior of the neck.

[0058] Typically, at least one vent opening is located on at least one side of each cavity in the shaft and / or head, facing away from the filling opening. In this way, when bone cement is filled, air in the cavity can easily escape, and as a result, no air bubbles remain in the cavity.

[0059] In one embodiment, the device includes or is made of a biocompatible material. For example, a biocompatible plastic material can be used. Biocompatibility means that when in direct contact with biological tissue, it does not adversely affect the metabolism of biological tissue.

[0060] In one embodiment, the device may include, or be made from, one or more of the following materials: polycarbonate, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, and polymethyl methacrylate.

[0061] In one embodiment, the device can be sterilized. In particular, the device can be sterilized by gamma rays, electron beam radiation, X-ray radiation, and / or ethylene oxide.

[0062] Further aspects of the present invention include, in particular, a device according to the present invention, - One additional head, which is positionable on the shaft of the device and is of a different size from the head of the device, and / or - At least one additional shaft capable of positioning the head of the device, which is of a different size from the shaft of the device. It is a system equipped with [this feature].

[0063] Different head sizes refer specifically to their diameters. Different shaft sizes refer specifically to their axial lengths and / or diameters.

[0064] In particular, there are at least two additional heads of different sizes. If needed, at least two additional shafts of different sizes are also available.

[0065] In one embodiment, the system includes at least three additional heads and at least three additional shafts. For example, there may be a total of four long shafts and four short shafts. Thus, with three or four locking steps for distance adjustment, dozens to hundreds of combinations are possible. The system may be packaged as a kit, thus making it available to medical professionals for surgical use.

[0066] A further aspect of the present invention is a method for determining a required distance between the head region and the shaft region of an articulated spacer, in which the head and shaft of the device are positioned at a desired distance from each other, and the distance between the head and shaft is fixed. The device may be a device according to the present invention. All the features, embodiments and advantages of the device described above may also apply to the method, and vice versa.

[0067] Another embodiment is a method for manufacturing a joint spacer, wherein the head and shaft of the device are positioned at a desired distance from each other, the distance is fixed, and bone cement is filled into the head and / or shaft.

[0068] The device may be a device according to the present invention. All the features, embodiments, and advantages of the device described above may also apply to the method, and vice versa.

[0069] First, the required distance is determined by positioning and fixing the head and shaft. Then, the joint spacer is fabricated using the device itself. Here, the device is used as a mold. After that, the bone cement hardens within the device. The bone cement is specifically polymethyl methacrylate (PMMA) bone cement.

[0070] This method may further include one or more of the following steps in any combination. - The process of connecting the head and neck. - A process of displacing the head on the neck to set the required distance. - A process of locking the displacement by bringing the pin into contact with one or two shape-locking elements and / or by rotating the head about its longitudinal axis relative to the neck. - A process of switching from an open position to a closed position, in particular by rotating a rotating unit, in particular by pushing a button out of a recess, in order to fix the distance between the head and the shaft and / or to lock the rotation of the head relative to the neck.

[0071] In particular, each cavity in the head and / or shaft is filled at least partially with bone cement. This is done especially through the filling openings.

[0072] In one embodiment, the outer shell of the device forms the outer shell of the spacer. In other words, after the bone cement hardens, the outer shell of the device defines or functions as the outer shell of the spacer. Thus, the device is used as a lost mold for manufacturing the spacer.

[0073] A further aspect of the present invention is the use of a disappearing mold for manufacturing a joint spacer.

[0074] In particular, a device for determining the required distance from the shaft region to the head region of a joint spacer is used as a disappearing mold for manufacturing the joint spacer. The device may be a device according to the present invention.

[0075] Lost-wax formwork is a formwork that remains in place after the part to be cast has been manufactured, and thus becomes part of the manufactured part.

[0076] Embodiments of the present invention are further described below in detail with reference to the drawings. Unless otherwise specified, features of the embodiments may be individually or combined with multiple claimed subject matter. The scope of the claimed protection is not limited to the embodiments. [Brief explanation of the drawing]

[0077] In the drawing,

[0078] [Figure 1] This is a perspective view of the device. [Figure 2] This is the process for using the device. [Figure 3] This is the process for using the device. [Figure 4] This is the process for using the device. [Figure 5] This is a disassembled view of the device. [Figure 6] This is the rotating unit of the device. [Figure 7] This is the process for using the device. [Figure 8] This is the process for using the device. [Figure 9] This is the process for using the device.

[0079] Figure 1 shows a device 10 for determining the required distance between the head region and the shaft region of a joint spacer. An example joint spacer 1 is shown in Figure 9.

[0080] The device 10 comprises a head 11 and a shaft 13. In principle, the head 11 and the shaft 13 can be positioned at different distances from each other. The neck 12 of the device is fixed at an angle to the shaft 13. The neck 12 may have an extension 14 at its free end that faces away from the shaft 13. The extension 14 may have a smaller diameter than the shaft 13. In the example shown herein, the head 11 may be positioned on the neck 12, particularly on its extension 14. In this case, the extension 14 can be inserted into the head 11 to a desired depth.

[0081] Furthermore, the device includes a fixing device 15 that can fix the distance between the head 11 and the shaft 13. In the embodiment shown herein, part of the fixing device 15 is located on or within the head 11, and part of the fixing device 15 is located on the neck 12. Thus, the fixing device 15 shown herein is designed to fix the relative position between the head 11 and the neck 12.

[0082] Details of the fixing by the fixing device 15 are shown in Figures 2 to 4. Figure 2 is a cross-sectional view of the head 11 and a perspective view of the neck 12. The neck 12 and the head 11 are separate from each other and are located on a common axis, i.e., the longitudinal axis 25 of the neck 12. The head 11 can be pressed onto the neck 12 along this axis and fixed therein. A scale 28 is provided, on which the relative position of the head 11 with respect to the neck 12, or the distance between the head 11 and the shaft 13, can be read.

[0083] On or within the head 11 are two pins 17 spaced apart from each other in the axial direction. In particular, for each pin 17 there is an additional pin 17' which is a duplicate of the respective pin 17 rotated 180° around the longitudinal axis 25. The neck 12 has two sets of shape locking elements 18. The shape locking elements 18 are designed as parallel webs extending along the circumferential direction of the neck 12 on its surface. There is a gap between each adjacent shape locking element 18. An axially extending groove 19 is positioned circumferentially next to the shape locking elements 18, connecting the gaps to each other. On the invisible underside, in particular there are two sets of additional shape locking elements 18'. These are duplicates of each set of shape locking elements 18 rotated 180° around the longitudinal axis 25.

[0084] When the head 11 is pressed against the neck 12, each pin 17 and each additional pin 17', if present, moves axially within the groove 19. Such positions are shown in Figure 3.

[0085] Next, as the head 11 is rotated clockwise relative to the neck 12, the pin 17 and further pins 17' move into one of the gaps and are held against axial displacement by the adjacent shape locking element 18 or further shape locking element 18'. In this way, the distance between the head 11 and the neck 12, and therefore the distance between the head 11 and the shaft 13, is also fixed.

[0086] To prevent this locking from being accidentally released, a locking element 27 is provided that can be moved into the groove area. In this way, it is possible to prevent each pin 17 or any additional pins 17' from moving out of the gap into the groove 19. The locking element 37 is part of a switching device 20 designed to switch from an open position 21 shown in Figure 3 to a closed position 22 shown in Figure 4. In the open position 21, the pins 17 and, if applicable, any additional pins 17' can be moved into the groove 19 by relative rotation between the head 11 and the neck 12, and as a result, the head 11 can be moved axially relative to the shaft 13. Thus, the distance between the head 11 and the shaft 13 can be changed. However, in the closed position 22, movement of the pins 17 and, if applicable, any additional pins 17' out of the gap is prevented. Thus, any movement between the head 11 and the shaft 13 is prevented. The distance between the head 11 and the shaft 13 is fixed.

[0087] In the embodiments shown herein, the locking element 27 is part of a rotating unit 26 that is located inside the neck 12 and rotatable relative to the outer housing portion 23 of the neck 12. This will be described in more detail with reference to Figures 5 and 6. The rotating unit may include a further locking element 27' which is a duplicate of the locking element 27 rotated 180° around the longitudinal axis 25 (see Figure 6).

[0088] Figure 5 is an exploded view of device 10 as an example. In addition to the components already described, the head 11, neck 12, and shaft 13, a rotary unit 26 can be seen, which is part of the switching device 20, on which the locking element 17 is located. The rotary unit 26 further comprises a button 30 connected to the rest of the rotary unit 26 via a spring element 33. The housing portion 23 of the neck 12, on which the rotary unit 26 is rotatably positioned, has two recesses 31, 32, each designed to receive the button 30. In the illustrated embodiment, the recesses 31, 32 are adjacent to and connected to each other. When the button 30 is located in the first recess 31, the device 10 is in the closed position 22. When the button 30 is located in the second recess 33, the device 10 is in the open position 21.

[0089] Button 30 can be pushed radially inward against spring force. In this way, button 30 can be released from recesses 31, 32. Here, the rotating unit 26 can rotate button 30 relative to the housing portion 23 until it reaches the other recess 32, 31 and snaps into place radially outward by spring force. By being positioned within their respective recesses, their respective open or closed positions are fixed, and the current position of the locking device can be easily seen. For this purpose, corresponding labels are usually provided in the area of ​​recesses 31, 32 and / or button 30, as shown as examples in Figures 3 to 6.

[0090] Figure 6 is an enlarged partial cross-sectional view of the rotating unit 26, in which the button 30 and spring element 33 can be seen. The spring element is, for example, a plate-shaped or tongue-shaped portion, which can be made of, for example, a plastic material and can be manufactured integrally with the button and / or the entire rotating unit 26. In the cross-sectional view shown on the left, a locking element 27 projecting radially outward and a correspondingly designed further locking element 27' can be seen.

[0091] Figures 7 to 9 show further embodiments of the present invention. The device 10 according to Figure 7 comprises an outer shell 35 defining an internal cavity 34 outward, specifically in the regions of both the head 11 and the shaft 13. In other words, the head 11 and the shaft 13 are at least partially hollow. The outer shell has a filling opening 36 into which bone cement or another suitable material can be filled. The device 10 further has vent openings 37 in the outer shell 35. These are preferably arranged to allow extruded air to escape when filling with bone cement 40 using, for example, one or more applicators 38, as shown in Figure 8. Since the cavity 34 in the neck 12 is connected to the cavity 34 in the head 11 and / or the cavity 34 in the shaft 13, the bone cement 40 can flow indirectly into it through the respective connection points.

[0092] Figure 9 shows the state after complete filling and hardening of the bone cement 40. Device 10 here becomes the joint spacer 1. The joint spacer 1 is individually fitted to the patient's anatomical structure. The head 11, neck 12, and shaft 13 of device 10 become the head region 2, neck region 4, and shaft region 3 of the joint spacer 1. The joint spacer is manufactured and consists of device 10 and the filled and hardened bone cement 40. The outer shell 35 of device 10 becomes the outer shell 5 of the joint spacer 1, further including a vent opening 37 and a filling opening 36.

[0093] In addition to the existing openings 36 and 37, the device 10 or joint spacer 1 may have an exit opening 39 through which an active substance can pass from the inside to the outside of the joint spacer 1 and to the patient. For example, an active substance containing one or more antibiotics may be added to the bone cement 40 before filling and during infectious replacement surgery to specifically address pre-existing bacteria.

[0094] The outlet opening 39 does not need to be different from the vent opening 37; rather, the vent opening 37 can function as the outlet opening 39, and vice versa. However, it is advantageous if the outlet opening 39 is distributed in several locations, possibly across the entire surface, particularly in locations where the vent opening 37 is only slightly effective, such as near the filling opening 36. [Explanation of symbols]

[0095] 1. Joint spacer 2 Head Area 3. Shaft area 4 Neck Area 5. Outer shell 10 devices 11 heads 12 neck 13 shafts 14 Extension 15 Fixation device 17 pins 17' Further pin 18 Shape Locking Elements 18' Further shape locking elements 19 Groove 20 Switching device 21 Open position 22 Closed position 23 Housing section 25 Longitudinal axis 26 Rotation Unit 27. Rock elements 27' Further rock elements 28 scale 30 heads 31 First recess 32 Second recess 33 Spring elements 34 Cavity 35 Outer shell 36 Filling opening 37 Vent opening 38 Applicators 39 Exit opening 40 Bone cement

Claims

1. A device (10) for determining the required distance from the shaft region (3) to the head region (2) of a joint spacer (1), comprising a head (11) and a shaft (13) that can be positioned at different distances from each other, wherein the device (10) further comprises a fixing device (15) for fixing the distance between the head (11) and the shaft (13).

2. The device (10) according to claim 1, further comprising a neck (12) that connects the head (11) to the shaft (13).

3. The device (10) according to claim 1, characterized in that the head (11) on one side and the shaft (13) and / or the neck (12) on the other side are separated from each other or can be separated from each other.

4. The device (10) according to claim 2, wherein the head (11) is displaceable on the neck (12), and the fixing device (15) comprises at least one pin (17) and a plurality of shape locking elements (18), wherein the pin (17) can be made to contact one or two shape locking elements (18) so as to prevent the displacement of the head (11) on the neck (12).

5. The device (10) according to claim 4, characterized in that grooves (19) aligned in the axial direction are arranged adjacent to the plurality of shape locking elements (18), and the pin (17) can be displaced in the axial direction within the grooves (19) to adjust the distance.

6. The device (10) according to claim 1, wherein the fixing device (15) comprises a switching device (20) for switching from an open position (21) to a closed position (22), the distance between the head (11) and the shaft (13) can be changed in the open position (21), and the distance between the head (11) and the shaft (13) is fixed in the closed position (22).

7. The device (10) according to claims 2 and 6, characterized in that the switching is performed by the rotation of a rotating unit (26) relative to a housing portion (23) about the longitudinal axis (25) of the neck (12).

8. The device (10) according to claim 6, characterized in that it is provided with a locking element (27) that is activated when switching to the closed position (22) and prevents any movement between the head (11) and the shaft (13).

9. The device (10) according to claim 8, wherein the locking element (27) is connected to a spring-loaded button (30) which cooperates with two recesses (31, 32), the button (30) is positioned in the first recess (31) when the fixing device (15) is in the closed position (22), and the button (30) is positioned in the second recess (32) when the fixing device (15) is in the open position (21).

10. The device (10) according to claim 4, wherein the fixing device (15) further comprises at least one further pin (17') located at a position rotated 180° around the longitudinal axis (25) starting from the pin (17), and the fixing device (15) further comprises a further plurality of shape locking elements (18') located at a position rotated 180° around the longitudinal axis (25) starting from the plurality of shape locking elements (18).

11. The device (10) according to claim 1, wherein the device (10) comprises an outer shell (35) in the region of the head (11) and / or the shaft (13), the outer shell defining a cavity (34) outward, and a filling opening (36) for filling the cavity (34) with bone cement is provided in the outer shell (35).

12. The device (10) described in claim 1, - At least one additional head (11) that can be positioned on the shaft (13) of the device (10), and / or the additional head (11) being of a different size from the head (11) of the device (10), and / or - At least one additional shaft (13) capable of positioning the head (11) of the device (10), the at least one additional shaft (13) being of a different size from the shaft (13) of the device (10), A system that includes these features.

13. A method for manufacturing a joint spacer (1), wherein the head (11) and shaft (13) of a device (10) are positioned at a desired distance from each other, the distance is fixed, and bone cement (40) is filled into the head (11) and / or the shaft (13).

14. The method according to claim 13, wherein the outer shell (35) of the device (10) forms the outer shell (5) of the joint spacer (1).

15. Use of a disappearing mold for manufacturing the aforementioned joint spacer (1).

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