Device, method and use for determining distance

Abstract

The present invention relates to an apparatus, a system, a method for manufacturing a joint spacer and use for determining a desired distance between a head region and a shaft region of a joint spacer. A device (10) for determining a desired distance between a head region (2) and a shaft region (3) of a joint spacer (1) comprises a head (11) and a shaft (13) which can be positioned at different distances relative to one another, where the device (10) further comprises a fixing device (15) for fixing the distance between the head (11) and the shaft (13). The device allows for intraoperatively determining the desired shape of the hip spacer by adjusting the distance of the head from the shaft for a particular anatomy of the patient.

Description

[0001] This invention relates to apparatus, systems, methods, and uses for determining the desired distance between the head region and axis region of a joint spacer. Preferably, the apparatus is also designed to combine any head with any axis to obtain a joint spacer optimally suited to the patient's anatomy.

[0002] In the context of two-stage replacement surgery using built-in prostheses (such as total arthroscopic prostheses for the hip or shoulder), spacers are used as temporary locators in the intermediate stage. This is specifically used in septic replacement surgery. Such spacers are typically fabricated by medical personnel during the surgery, for example, from bone cement (such as polymethyl methacrylate bone cement). During the fabrication of these spacers, one or more antibiotics specifically tailored to the present pathogens may be added to the bone cement, depending on the available antimicrobial spectrum of the microorganism causing the infection.

[0003] Prefabricated spacers already exist, offering high stability but not being suitable for the individual anatomy of patients. Therefore, it is preferable to fabricate individual spacers during surgery.

[0004] For surgically fabricated spacers that typically use bone cement, plastic casting molds are commonly used, such as those described in US 6,361,731 B1. These casting molds can be manufactured with different diameters for the spacer head. In this case, the medical user can choose between predetermined sizes for the spacer head. In this way, customized spacers can be provided to patients depending on their specific anatomical situation. Spacers used for joints or joint segments are called joint spacers.

[0005] In development, documents US 7 637 729 B2, US 7 789 646 B2, US 8 480 389 B2, and US 8801 983 B2 proposed multi-part casting molds for manufacturing modular hip joint spacers. The casting molds from documents US 7 789 646 B2, US 8 480 389 B2, and US 8 801 983 B2 consist of a casting mold for the shaft, which can be connected to a casting mold for the spacer head. Casting molds for the spacer head with different diameters are available. The shaft casting mold is connected to the spacer head casting mold with a selected diameter. The casting mold thus assembled can then be filled with bone cement. After curing, the formed hip joint spacer is removed.

[0006] Document EP 3 957 280 B1 describes an apparatus for manufacturing hip joint spacers that allows for the manufacture of patient-specific hip joint spacers with regard 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 object of this invention is to simply and repeatably determine the desired shape of the joint spacer in order to improve the manufacture of individual fits of the joint spacer.

[0008] This objective is achieved by the device according to claim 1, and the system, method, and use according to the cooperating claims. Advantageous embodiments can be found in the dependent claims.

[0009] To achieve this objective, a device is used to determine the desired distance between the head region and the shaft region of the joint spacer. The device includes a head and a shaft, which can be positioned relative to each other at different distances. The device also includes a fixing device for securing the distance between the head and the shaft.

[0010] This device is designed to be temporarily inserted into the patient at the location of the spacer to be inserted in order to determine the desired distance between the head region and the axis region of the spacer, or to determine whether the selected distance is suitable for a specific anatomical condition. The device is designed to fix the selected distance between the head and the axis to prevent any accidental change in distance or any possible accidental separation of the axis and the head, which could result in loss of the head. Specifically, the distance is fixed during use within the patient. This device may also be referred to as a test gauge.

[0011] This device allows the desired shape of the hip spacer to be determined during surgery by adjusting the distance between the head and the axis (also known as "femoral offset") for the patient's specific anatomy. This means that the correct spacer can be selected individually for each patient. For example, the spacer can then be fabricated intraoperatively using a hip spacer mold and / or according to document EP 3 957 280 B1.

[0012] The spacer to be manufactured and inserted includes a head region (head), an axis region (axis), and an intermediate neck region (neck) connecting the head region and the axis region (neck) (if desired). The spacer (specifically, at least in its head region) is modeled according to the shape and size of the corresponding bone (e.g., the femur (thigh bone)). The axis region of the spacer is inserted into an opening in the bone and is typically fixed there. The head region of the spacer is approximately spherical in at least some areas to reproduce, for example, a movable connection to the pelvis (in this case, the hip joint). The spacer may also include a neck region connecting the axis to the head.

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

[0014] The head and shaft are typically movable relative to each other (specifically, linearly displaced) for positioning at different distances. A fixing device secures the head directly or indirectly to the shaft. In the locked (fixed) state, the head and shaft are connected in such a way that at least a change in distance between them is prevented (via a neck between them if necessary). For example, this could be axial movement relative to the shaft or the longitudinal axis of the neck located between the shaft and the head. The longitudinal axis specifically refers to the central longitudinal axis.

[0015] In a simple implementation, the shaft and the head are connected by threads. For example, the shaft or the neck connected to the shaft has external threads, and the head has internal threads. The axial position of the head relative to the shaft can then be adjusted by relative rotation.

[0016] For example, the fixing device may include a pin, designed to be retractable to secure the head relative to the shaft. For this purpose, the pin can be moved into a suitable receiving portion, for example. Alternatively or additionally, the fixing device may include a locking element, which may be pre-tensioned by a spring. In this way, when the head is locked and secured by the spring, movement between the head and the shaft can be prevented. If the locking element is released against the spring force (e.g., by manual pressing), movement between the head and the shaft can be released. It may be specified that movement is only permitted when the locking element is pressed.

[0017] In one embodiment, the device further includes a neck for attaching the head to the shaft. Specifically, the neck is securely attached to the shaft. The neck may be integral with the shaft. Specifically, the head is designed to be pushed onto or screwed onto and / or secured to the neck.

[0018] Specifically, the neck is designed to allow for different distances between the axis 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 axis. In the femoral region, the angle may correspond to the CCD angle (femoral head-neck-shaft angle). The angle may be at least 100°, preferably at least 110°, specifically at least 120° and / or at most 160°, preferably at most 150°, specifically at most 140°. This design allows for the manufacture of a particularly well-fitting spacer that is optimally adapted to the patient's anatomy.

[0020] In one implementation, the head on one side and the shaft and / or neck on the other side are separated from each other or are capable of being separated from each other.

[0021] In this embodiment, the shaft and head can be connected to each other (possibly indirectly via the neck) and then secured relative to each other in a desired position by a fixation device. This allows for the replacement of the head or shaft, or allows for specific selection to use different combinations of shaft and head. For example, a desired head size optimally suited to the patient's anatomy can be selected. Alternatively or additionally, a shaft of a specific length and / or diameter optimally suited to the patient's anatomy can be selected.

[0022] In one embodiment, the head can be displaced on the neck. The restraint device includes at least one pin and a plurality of shape-locking elements. The pin is capable of engaging one or two shape-locking elements in a manner that prevents displacement of the head on the neck.

[0023] A pin is arranged on one of two parts that can be displaced relative to each other, specifically on the head. A shape-locking element is arranged on the other of the two parts that can be displaced relative to each other, specifically on the neck. Specifically, the head can be displaced axially on the neck relative 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. Specifically, the axial position of the head on the neck is fixed.

[0024] A pin is a protruding element relative to its surroundings. A pin can have a circular or square cross-section, or, for example, an elongated or rectangular cross-section. In principle, a pin can have any shape. To prevent displacement, it is only necessary that the pin can sequentially contact the shape-locking element. Specifically, the pin must be aligned at least approximately in the radial direction.

[0025] The pin can typically contact any shape-locking element. Shape-locking elements are typically arranged in different positions relative to the longitudinal axis of the element having the shape-locking element, specifically in rows. By selecting the shape-locking element to contact the pin, the relative position and thus distance between the head and neck are secured. The shape-locking elements are specifically aligned in the circumferential direction.

[0026] In principle, contact between the pin and a shape-locking element is sufficient to prevent displacement in one direction. Preferably, the pin may be arranged between two shape-locking elements to prevent displacement in both directions. Specifically, in each case, a gap exists between two adjacent shape-locking elements, and the pin may be positioned in this gap to fix the distance.

[0027] In principle, there are at least three shape-locking elements and two gaps between them, such that two different distances can be set depending on the choice of the gaps. Specifically, there are at least four or five or more shape-locking elements.

[0028] Specifically, there are two pins spaced apart from each other in the axial direction. Typically, the two pins lie on an imaginary line extending in the axial direction. The axial direction refers to the component with the pins. In this way, blockage is reliably prevented. Two sets of shape-locking elements and a gap between them may exist. Each pin can then engage with one set of shape-locking elements.

[0029] In one embodiment, the axial alignment groove is arranged adjacent to a plurality of shape-locking elements. The pin is capable of axial displacement within the groove. Therefore, the distance can be set.

[0030] In this configuration, the shape-locking element is specifically comb-shaped. An axial alignment groove adjacent to the shape-locking element is used to specifically displace the head over the neck. A pin specifically arranged on the head can slide within the groove, allowing for axial displacement of the head over the neck. In a plan view, the gap and / or the shape-locking element are arranged perpendicular to the groove.

[0031] Specifically, engagement is achieved by rotating the head relative to the neck about an axial axis, wherein a pin is arranged between two shape-locking elements and prevents axial displacement. Therefore, after setting the desired distance, the set distance can be fixed by the relative rotation of the head relative to the neck.

[0032] Specifically, the groove is arranged relative to the circumferential surface of the component having the groove in an angular position of the component adjacent to the shape locking element or its gap. Specifically, the groove is directly connected to the corresponding gap, such that during relative rotation, the pin can move from the groove to one of the gaps, and in this way, the distance can be fixed.

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

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

[0036] In principle, switching can be achieved by moving one part of the device relative to another part of the device, for example by moving the switch relative to a housing portion. The movement can 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 achieved by simply shifting it. It may be necessary to perform a rotation before shifting, for example, to disengage the pin from one or more shape-locking elements. Specifically, movement between the head and the shaft is possible in the open position.

[0038] This implementation prevents undesirable displacement of the head relative to the neck and loosening of the head, for example, when testing the possible shape of the spacer in a patient using a device.

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

[0040] In one embodiment, switching is achieved by rotating a rotating unit about the longitudinal axis of the neck relative to the housing portion. The rotating unit is a unit mounted to allow it to rotate. Specifically, switching back to the other position can then be accomplished, for example, by rotating it again in the opposite direction.

[0041] Specifically, the neck has a housing. The housing defines the outer shell of the neck. The housing represents the transition between the head (e.g., a different head) and the shaft (e.g., a different shaft), and can therefore also be called an adapter. Specifically, the rotating unit can rotate relative to the entire housing.

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

[0043] If switching is achieved by rotating a rotating unit relative to the housing portion, and if the rotating unit is rotatable relative to the housing portion about the longitudinal axis of the neck, then the locking element can be part of the rotating unit. Therefore, the locking element can be easily activated and deactivated by rotation. Specifically, the locking element is part of the switching device.

[0044] In the closed position, the locking element prevents the pin from moving out of the gap between the two shape-locking elements in the circumferential direction. This prevents the rotating unit from rotating in the neck or neck housing. The locking element may be an axially extending web. An axial groove or recess may be present near the web in the radial direction, allowing the pin to move out of the gap in the open position.

[0045] For example, a window-like opening may be present in the housing of the neck, through which the locking element can be moved (e.g., 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 fix the desired distance.

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

[0048] Therefore, the button's positioning indicates the off or on position. The button is specifically located on the rotating unit. The recess is specifically located within the housing portion. The button is typically fixed in the recess in a manner that prevents switching (e.g., by shape locking). Specifically, rotation of the rotating unit relative to the housing portion is impossible because the button is arranged in the recess in a way that prevents rotation of the rotating unit relative to the housing portion. To switch, the button can be pushed radially inward, causing it to overcome the spring force and extend beneath the material forming the recess. In this position, the rotatable portion can rotate relative to the housing portion. If the button is then located beneath another recess, it is pushed radially outward by the spring force and thus locks into another recess. The device is now in the corresponding other position.

[0049] The two recesses are specifically window-shaped and therefore can also be referred to as windows. The two recesses can be connected. Therefore, there can be two distinct defined regions of a single recess, which, according to the invention, are referred to as the two recesses. Specifically, the two recesses are arranged at different angular positions relative to the longitudinal axis. Specifically, the two recesses are arranged at the same length relative to the longitudinal axis.

[0050] The button is part of the locking element and is specifically and securely connected to it. Therefore, the locking element and the button rotate together about a longitudinal axis. Specifically, the button is attached to a leaf spring and preloaded outwards. For example, a visual symbol may be arranged near the recess to indicate the corresponding position (open / closed position), so that the current position can be directly seen based on the button's location.

[0051] In one embodiment, the fastening device further includes at least one additional pin, starting from which the at least one additional pin is positioned about 180° rotated about the longitudinal axis. Alternatively or additionally, the fastening device further includes a plurality of additional shape-locking elements, starting from a plurality of shape-locking elements, which are positioned about 180° rotated about the longitudinal axis.

[0052] Therefore, the fixation against axial movement occurs at two relative positions. This prevents tilting relative to the longitudinal axis and ensures a secure fixation. Two webs and two sets of shape-locking elements may be present in each angular position to prevent tilting perpendicular to the longitudinal axis.

[0053] In one embodiment, the device has a housing located in the head and / or shaft region, the housing defining a cavity outwards. Specifically, a filling opening for filling bone cement into the cavity is arranged in the housing.

[0054] The housing is typically not completely hollow. Specifically, a cavity extends between the housing and a core, which may be made of metal, of the head or shaft device. The core is used to stabilize and / or set the device. Specifically, the head and / or shaft are at least partially hollow. The neck may also be partially hollow. The device may include additional metal reinforcements in the shaft and / or neck.

[0055] The filling opening is used to fill the bone cement. The filling opening is typically designed to accommodate any filler. The bone cement then hardens within the device, forming a strong and stable spacer.

[0056] Specifically, in this case, the device can be used as a lost-wax mold. The shell is then left on the bone cement and, together with the bone cement and possibly one or more cores (e.g., made of metal), forms a spacer. This allows for the direct fabrication of dimensionally stable spacers from the device. Typically, at least one filling opening is present in the head and at least one filling opening is present in the shaft.

[0057] Particularly preferred is that at least the outer casing of the device is made of polymethyl methacrylate. A channel may be present in the shaft-facing end of the neck through which bone cement already filled into the shaft can flow into the interior of the neck.

[0058] Typically, at least one ventilation opening is arranged on the side of the corresponding cavity in the shaft and / or head opposite to the filling opening. In this way, air in the cavity can easily flow out during filling with bone cement, so that no air bubbles are retained in the cavity.

[0059] In one embodiment, the device includes or is made of a biocompatible material. For example, a biocompatible plastic material may be used. Biocompatibility refers to the property that it does not have a negative impact on the metabolism of living tissue when in direct contact with it.

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

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

[0062] Another aspect of the invention is a system comprising a device specifically according to the invention and

[0063] - At least one additional head, which can be positioned on the axis of the device, having a different size from the head of the device, and / or

[0064] - At least one additional shaft, on which the head of the device can be positioned, the shaft having a different size from the shaft of the device.

[0065] The different dimensions of the head specifically refer to its diameter. The different dimensions of the shaft specifically refer to its axial length and / or diameter.

[0066] Specifically, there are at least two additional heads, each with a different size. At least two additional shafts of different sizes are available if needed.

[0067] In one implementation, the system includes at least three additional heads and at least three additional axes. For example, a total of four long axes and four short axes may be present. Thus, with three or four locking steps for distance adjustment, dozens to hundreds of combinations are possible. The system can be packaged as a kit and thus made available to medical personnel for use in surgical procedures.

[0068] Another aspect of the invention is a method for determining a desired distance between a head region and a shaft region of a joint spacer, wherein the head and shaft of the device are positioned relative to each other at a desired distance, and the distance between the head and the shaft is fixed. The device can be one according to the invention. All the features, embodiments, and advantages of the above-described device are also suitable for this method, and vice versa.

[0069] On the other hand, there is a method for manufacturing joint spacers, in which the head and shaft of the device are positioned relative to each other at a desired distance, the distance is fixed, and bone cement is filled into the head and / or the shaft.

[0070] The device can be the device according to the present invention. All the features, embodiments and advantages of the above-described device can also be adapted to the method, and vice versa.

[0071] First, the required distance is determined by positioning and fixing the head and shaft. Then, the device itself is used to manufacture the joint spacer. The device serves as a casting mold. Bone cement then hardens within the device. Specifically, the bone cement is polymethyl methacrylate (PMMA) bone cement.

[0072] The method may also include one or more of the following steps in any combination:

[0073] -Connects the head and neck,

[0074] - Move the head above the neck to set the desired distance.

[0075] - The displacement is locked by contacting the pin with one or two shape-locking elements and / or by rotating the head relative to the neck about the longitudinal axis.

[0076] - Switch from the open position to the closed position to fix the distance between the head and the axis and / or lock the rotation of the head relative to the neck, specifically by rotating the rotating unit, specifically by pushing the button out of the recess.

[0077] Specifically, the corresponding cavities in the head and / or shaft are at least partially filled with bone cement. This is specifically done via filling openings.

[0078] In one embodiment, the housing of the device forms the housing of the spacer. In other words, after the bone cement has hardened, the housing of the device defines the housing of the spacer or serves as the housing for the spacer. Thus, the device is used as a lost foam shell for manufacturing spacers.

[0079] Another aspect of the invention is the use of lost foam shells in the manufacture of joint spacers.

[0080] Specifically, the device used to determine the required distance between the head region and the shaft region of the joint spacer is used as the lost-cast shell for manufacturing the joint spacer. This device can be the device according to the invention.

[0081] A lost foam shell is a mold that remains in place after the part to be cast has been manufactured and thus becomes part of the manufactured component.

[0082] Embodiments of the invention are explained in more detail below with reference to the accompanying drawings. Unless otherwise indicated, features of the embodiments may be combined with the claimed object, individually or in combination. The scope of protection claimed is not limited to the embodiments.

[0083] In the attached diagram:

[0084] Figure 1 This is a perspective view of the equipment.

[0085] Figures 2 to 4 These are the steps for using the equipment.

[0086] Figure 5 This is an exploded view of the equipment.

[0087] Figure 6It is the rotating unit of the equipment, and

[0088] Figures 7 to 9 : These are the steps used to operate the equipment.

[0089] Figure 1 This is a device 10 used to determine the required distance between the head region and the shaft region of a joint spacer. Figure 9 The joint spacer 1 is shown as an example.

[0090] Device 10 includes a head 11 and a shaft 13. In principle, the head 11 and shaft 13 can be arranged at different distances relative to each other. A neck 12 of the device is fixed to the shaft 13 at an angle. The neck 12 may have an extension 14 at its free end pointing away from the shaft 13. The extension 14 may have a smaller diameter compared to the shaft 13. In the example shown here, the head 11 can be placed on the neck 12, specifically on its extension 14. In this case, the extension 14 can be immersed in the head 11 to a desired depth.

[0091] Furthermore, the device includes a fixing device 15, which can be used to fix the distance between the head 11 and the shaft 13. In the embodiment shown here, a portion of the fixing device 15 is arranged on or in the head 11, and a portion of the fixing device 15 is arranged on the neck 12. Therefore, the fixing device 15 shown here is designed to fix the relative position between the head 11 and the neck 12.

[0092] Figures 2 to 4 The details of fixing using the fixing device 15 are shown. Figure 2 This is a 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 arranged on a common axis (i.e., the longitudinal axis 25 of the neck 12). The head 11 can be pushed onto the neck 12 along this axis and fixed there. A scale 28 is provided on which the relative position of the head 11 and the neck 12 or the distance between the head 11 and the axis 13 can be read.

[0093] Two pins 17 are present on or within the head 11, axially spaced apart from each other. Specifically, for each pin 17, there is another pin 17', which is a replica of the corresponding pin 17 rotated 180° about the longitudinal axis 25. Two sets of shape-locking elements 18 are present on the neck 12. The shape-locking elements 18 are designed with parallel webs that extend along the circumferential direction of the neck on the surface of the neck 12. Corresponding gaps are arranged between adjacent shape-locking elements 18. Grooves 19 extending in the axial direction are arranged circumferentially close to the shape-locking elements 18, thereby connecting the gaps to each other. Specifically, two additional sets of shape-locking elements 18' are present on the invisible lower side. These are each replicas of the corresponding set of shape-locking elements 18 rotated 180° about the longitudinal axis 25.

[0094] If the head 11 is pushed onto the neck 12, each pin 17 and each additional pin 17' (if present) moves axially within the groove 19. Such a position is... Figure 3 As shown in the image.

[0095] If the head 11 is subsequently rotated clockwise relative to the neck 12, pin 17 and another pin 17' move into one of the gaps and are held by the adjacent shape-locking element 18 or another shape-locking element 18' to prevent displacement in the axial direction. 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 fixed.

[0096] To prevent accidental release of the fastener, a locking element 27 is provided that can move into the recessed area. In this way, the corresponding pin 17 or another pin 17' is prevented from moving out of the gap into the recess 19. The locking element 37 is part of the switching device 20, which is designed to... Figure 3 The opening position 21 shown is switched to Figure 4 The closed position 22 is shown. In the open position 21, pin 17 and additional pins 17' (if applicable) can be moved into the recess 19 by relative rotation between the head 11 and the neck 12, and thus the head 11 can move axially relative to the shaft 13. Therefore, the distance between the head 11 and the shaft 13 can be changed. However, in the closed position 22, movement of pin 17 and additional pins 17' (if applicable) out of the gap is prevented. Therefore, any movement between the head 11 and the shaft 13 is prevented. The distance between the head 11 and the shaft 13 is fixed.

[0097] In the embodiment shown here, the locking element 27 is part of a rotating unit 26, which is arranged within the neck 12 and is rotatable relative to the outer housing portion 23 of the neck 12. (This reference...) Figure 5 and Figure 6To explain in more detail. The rotating unit may include an additional locking element 27', which is a replica of the locking element 27 rotated 180° about the longitudinal axis 25 (see [link]). Figure 6 ).

[0098] For example, Figure 5 This is an exploded view of device 10. In addition to the already described components head 11, neck 12, and shaft 13, a rotating unit 26, which is part of the switching device 20, is also visible, and a locking element 17 is located on this rotating unit. The rotating unit 26 also includes a button 30, which is connected to the rest of the rotating unit 26 via a spring element 33. Two recesses 31 and 32 are present on the housing portion 23 of the neck 12 (in which the rotating unit 26 is rotatably arranged), each of which is designed to receive the button 30. In the illustrated embodiment, the recesses 31 and 32 are adjacent to and connected to each other. If the button 30 is located in the first recess 31, device 10 is in the closed position 22. If the button 30 is located in the second recess 33, device 10 is in the open position 21.

[0099] The button 30 can be pressed radially inward against the spring force. Therefore, the button 30 can be released from the recesses 31 and 32. Now, the rotating unit 26 can rotate relative to the housing portion 23 until the button 30 reaches the other recesses 32 and 31 and is radially outward locked into the recesses due to the spring force. Due to the arrangement in the respective recesses, the corresponding open or closed position is fixed, and it is easy to see which position the fixing device is currently in. For this purpose, as by... Figures 3 to 6 As shown in the example, corresponding labels are typically provided in the areas of the recesses 31, 32 and / or the button 30.

[0100] Figure 6 This is an enlarged partial cross-sectional view of the rotating unit 26, showing the button 30 and the spring element 33. By way of example, the elastic element is a leaf-shaped or tongue-shaped portion, which may be made of, for example, plastic material, and may be integrally formed with the button and / or the entire rotating unit 26. In the cross-sectional view shown on the left, a radially outwardly projecting locking element 27 and a correspondingly designed additional locking element 27' can be seen.

[0101] Figures 7 to 9 This is another aspect of the invention. According to... Figure 7The device 10 includes a housing 35 that defines an inner cavity 34 facing outwards, particularly in the region 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 housing has a filling opening 36 through which bone cement or another suitable material can be filled. The device 10 also has ventilation openings 37 in the housing 35. These are preferably arranged such that when bone cement 40 is filled, for example with one or more applicators 38, as Figure 8 As shown, the displaced air can flow out. The cavity 34 of the neck 12 is specifically connected to the cavity 34 of the head 11 and / or the cavity 34 of the shaft 13, so that the bone cement 40 can flow there indirectly via the corresponding connection.

[0102] Figure 9 The diagram shows the situation after the bone cement 40 has been fully filled and hardened. Device 10 now becomes joint spacer 1. Joint spacer 1 is individually adapted to the patient's anatomy. The head 11, neck 12, and shaft 13 of device 10 become the head region 2, neck region 4, and shaft region 3 of joint spacer 1. Joint spacer is manufactured and consists of device 10 and filled and hardened bone cement 40. The housing 35 of device 10 becomes the housing 5 of joint spacer 1 and also includes ventilation openings 37 and filling openings 36.

[0103] In addition to the existing openings 36 and 37, the device 10 or joint spacer 1 may have an outlet opening 39 through which active substances can be delivered from the interior of the joint spacer 1 to the exterior and reach the patient. During septic replacement surgery, before filling, an active substance, for example including one or more antibiotics, may be added to the bone cement 40 to specifically combat existing pathogens.

[0104] The outlet opening 39 need not be different from the ventilation opening 37; on the contrary, the ventilation opening 37 can also be used as the outlet opening 39, and vice versa. However, it is advantageous if the outlet opening 39 is provided in several locations, possibly distributed across the entire surface, and specifically in locations where the ventilation opening 37 is only slightly effective, such as near the filling opening 36.

[0105] List of reference numerals in the attached figures

[0106]

[0107]

Claims

1. A device (10) for determining a desired distance between a head region (2) and a shaft region (3) of a joint spacer (1), the device comprising a head (11) and a shaft (13) capable of being positioned relative to each other at different distances, 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 the preceding claim, characterized in that, The device (10) also includes a neck (12) for connecting the head (11) to the shaft (13).

3. The device (10) according to any one of the preceding claims, 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 are capable of being separated from each other.

4. The device (10) according to any one of the preceding claims, characterized in that, The head (11) is displaceable on the neck (12), and the fixing device (15) includes at least one pin (17) and a plurality of shape locking elements (18), the pin (17) being able to contact one or two shape locking elements (18) in such a way that displacement of the head (11) on the neck (12) is prevented.

5. The device (10) according to the preceding claim, characterized in that, An axial alignment groove (19) is arranged adjacent to the plurality of shape locking elements (18), and the pin (17) is axially displaced in the groove (19) to adjust the distance.

6. The device (10) according to any one of the preceding claims, characterized in that, The fixing device (15) includes a switching device (20) for switching from an open position (21) to a closed position (22), in which the distance between the head (11) and the shaft (13) can be changed, and in the closed position (22), the distance between the head (11) and the shaft (13) is fixed.

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

8. The device (10) according to any one of the preceding claims, characterized in that, A locking element (27) is provided, which is activated when switched to the closed position (22) and prevents any movement between the head (11) and the shaft (13).

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

10. The device (10) according to any one of the six preceding claims, characterized in that, The fastening device (15) further includes at least one additional pin (17'), starting from the pin (17), the at least one additional pin being in a position rotated 180° about the longitudinal axis (25), and wherein the fastening device (15) further includes a plurality of additional shape locking elements (18'), starting from the plurality of shape locking elements (18), the plurality of additional shape locking elements being in a position rotated 180° about the longitudinal axis (25).

11. The device (10) according to any one of the preceding claims, characterized in that, The device (10) includes a housing (35) in the region of the head (11) and / or the shaft (13), the housing defining a cavity (34) to the outside, and a filling opening (36) for filling bone cement into the cavity (34) is arranged in the housing (35).

12. A system comprising the device (10) according to any one of the preceding claims and - At least one additional head (11) capable of being positioned on the shaft (13) of the device (10), wherein the head (11) has a different size than the head (11) of the device (10), and / or - At least one additional shaft (13), on which the head (11) of the device (10) can be positioned, wherein the shaft (13) has a different size than the shaft (13) of the device (10).

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

14. The method according to the preceding claims, wherein the housing (35) of the device (10) forms the housing (5) of the joint spacer (1).

15. The use of the lost foam shell in manufacturing the joint spacer (1).

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