Inverse shoulder spacer, mould, kit and method for producing an inverse shoulder spacer

Abstract

An inverse shoulder spacer (100) for temporary replacement of an artificial shoulder joint, comprising a glenoid component (110), which is designed as a convex half-ball (115) at a distal end of the glenoid component, and a humeral component (120) which, at a proximal end of the humeral component, has a concave ball receptacle (125) for receiving the half-ball of the glenoid component, wherein the half-ball along with the ball receptacle simulates or can simulate an inverse shoulder joint. The shoulder spacer additionally has one or more pins (130) which are each connected or connectable, with a respective pin end, to one of a plurality of concave pin receptacles (140) at a proximal end of the glenoid component, such that the shoulder spacer can be fastened via the one or more pins in anchoring holes in a glenoid of a patient.

Description

[0001] Inverse shoulder spacer, mold, kit and method for producing an inverse shoulder spacer

[0002] DESCRIPTION

[0003] The invention relates to an inverse shoulder spacer for temporarily replacing an artificial shoulder joint, comprising a glenoid component which is designed as a convex hemisphere at a distal glenoid component end, a humeral component which has a concave ball receptacle at a proximal humeral component end for receiving the hemisphere of the glenoid component, wherein the hemisphere with the ball receptacle simulates or can simulate an inverse shoulder joint.

[0004] The invention further relates to a casting mold and a kit comprising such a casting mold and a method for producing such a shoulder spacer.

[0005] Background of the invention

[0006] Joint prostheses, such as shoulder prostheses, currently have a service life of several years; for example, cemented hip prostheses average ten to fifteen years. However, unwanted loosening of joint prostheses can occur even before the usual service life has been reached. A distinction is made between septic and aseptic loosening. Microbial pathogens have not yet been detected in aseptic loosening. The causes of aseptic loosening can be varied. Aseptic loosening is often due to abrasion on the sliding surfaces of the joint prostheses.

[0007] In septic loosening, the loosening process is caused by microbial germs. A distinction is made between early and late infections depending on the timing of their onset. Septic loosening is a very serious condition for the patient, which is also associated with very high treatment costs. Both aseptic and septic loosening usually require revision. A distinction is made between one-stage and two-stage revisions. In cases of septic loosening, two-stage revisions are very often performed. In a two-stage revision, the infected joint endoprosthesis is removed in an initial operation (SUR), and infected tissue is removed in a process called debridement. A temporary placeholder, a so-called spacer, is then inserted. This spacer fills the space of the previously revised joint endoprosthesis for a few weeks until the existing infection has cleared up.This placeholder function is very important to effectively prevent muscle atrophy during this time and to achieve stabilization of the resection situation.

[0008] A distinction is made between non-articulating and articulating spacers. Articulating spacers mimic joint function and allow a certain degree of mobility in the affected limb. This makes it possible to mobilize patients early. Articulating spacers are therefore currently the most popular choice. Articulating spacers are primarily hip spacers, knee spacers, elbow spacers, or shoulder spacers. The spacer is removed in a second surgery, debrided again, and then a cemented or cementless revision joint prosthesis is implanted.

[0009] Spacers made of polymethyl methacrylate bone cement are generally state of the art as temporary spacers for two-stage septic revisions of artificial hip, knee, and shoulder joints. Examples include the following patents: US 6,361,731 B1, US 7,637,729 B2, US 7,789,646 B2, US 8,480,389 B2 and US 8,801,983 B2, US 7,637,729 B2, US 10,071,511 B2, EP 2651324 B1, and EP 2526900 B1. The spacers typically contain one or more antibiotics, which, after implantation, are dissolved from the spacer surface by the action of body fluid, providing antibiotic protection for the spacer surface.

[0010] In the area of ​​the articulating shoulder spacers, simple artificial shoulder joint prostheses replicate the natural anatomical position of the shoulder joint and replace the hemispherical head on the proximal humerus with a suitable hemisphere, which is secured by a stem in the humeral canal. A half-shell is fixed in the opposite glenoid to accommodate the hemispherical head.

[0011] However, there are cases where, for example, the rotator cuff, the proximal humerus and / or the glenoid are so severely damaged that such a simple shoulder joint prosthesis can no longer be effectively implanted. In these cases, so-called inverse shoulder prostheses are often used. A plate is screwed onto the glenoid, onto which a convex hemisphere is placed as a sliding surface. A stem is implanted in the humerus as a counterpart. This stem has a concave hemispherical receptacle for the hemisphere at its proximal end. The convex hemisphere and the concave hemispherical receptacle interlock to form an artificial joint constructed inversely to the normal anatomical situation. There are numerous manufacturers of inverse shoulder prostheses.These prostheses differ, among other things, in that the prosthetic component screwed to the glenoid has differently designed anchoring holes for bolts or screws to secure them to the glenoid. The anchoring holes are generally designed to allow for fixation at different angles to ensure secure anchoring of the glenoid component depending on the patient's specific glenoid anatomy.

[0012] However, no inverse shoulder spacers are known yet.

[0013] Tasks

[0014] An object of the present invention is to at least partially overcome one or more of the disadvantages resulting from the prior art.

[0015] Specifically, the invention is based on the goal of providing a reverse shoulder spacer. The shoulder spacer should be as simple as possible in design and be usable as a temporary replacement for a variety of different reverse shoulder prostheses. In particular, the shoulder spacer should be temporarily implantable without the need to create additional anchoring holes in the patient's glenoid.

[0016] It is a further object of the invention to provide a mold and a kit for producing an inverse shoulder pacer, by means of which at least some of the objects already described are at least partially achieved.

[0017] Furthermore, it is an object of the invention to provide a method for producing an inverse shoulder spacer, by means of which at least some of the objects already described are at least partially achieved. Preferred embodiments of the invention

[0018] A contribution to at least partially fulfilling at least one of the aforementioned objects is made by the features of the independent claims. The dependent claims provide preferred embodiments that contribute to at least partially fulfilling at least one of the objects.

[0019] A first embodiment of the invention is an inverse shoulder spacer for temporarily replacing an artificial shoulder joint, comprising a glenoid component which is designed as a convex hemisphere at a distal glenoid component end, a humeral component which has a concave ball socket at a proximal humeral component end for receiving the hemisphere of the glenoid component, wherein the hemisphere with the ball socket simulates or can simulate an inverse shoulder joint, characterized in that the shoulder spacer has one or more pins, each of which is or can be connected to a pin end with one of a plurality of concave pin sockets at a proximal glenoid component end of the glenoid component, so that the shoulder spacer can be fastened via the pin(s) in anchoring holes in a glenoid of a patient.

[0020] In one embodiment of the shoulder spacer, the humeral component and the glenoid component comprise a polymethylmethacrylate bone cement (PMMA bone cement), or the humeral component and the glenoid component are made of a polymethylmethacrylate bone cement. This embodiment is a second embodiment of the invention, which preferably depends on the first embodiment of the invention.

[0021] In one embodiment of the shoulder spacer, the pin receptacles are conical, with an inner periphery of the pin receptacles engaging a pin receptacle opening toward the distal end of the glenoid component. This embodiment is a third embodiment of the invention, which preferably depends on the first or second embodiment of the invention.

[0022] In one embodiment of the shoulder spacer, the conical pin receptacles have a lateral surface that forms an angle with a conical longitudinal axis of the pin receptacles in a range of 10-30°, preferably in a range of 15-30°, more preferably in a range of 20-30°. This embodiment is a fourth embodiment of the invention, which preferably depends on the third embodiment of the invention.

[0023] In one embodiment of the shoulder spacer, if more than one pin is present, the pins have a different diameter, in particular a different average diameter, a different length, or a different diameter, in particular a different average diameter and a different length. This embodiment is a fifth embodiment of the invention, which preferably depends on one of the previous embodiments of the invention.

[0024] In one embodiment of the shoulder pacer, the pin(s) comprise a pin metal core. This embodiment is a sixth embodiment of the invention, which preferably depends on one of the previous embodiments of the invention.

[0025] In one embodiment of the shoulder spacer, the humeral component has a humeral component metal core. This embodiment is a seventh embodiment of the invention, which preferably depends on one of the previous embodiments of the invention.

[0026] An eighth embodiment of the invention is a casting mold for producing an inverse shoulder spacer according to one of the preceding embodiments of the invention, comprising a humeral casting mold consisting of at least two parts for forming the humeral component, a glenoid casting mold consisting of at least two parts for forming the glenoid component and a pin casting mold consisting of at least two parts for forming the pin or pins.

[0027] In one embodiment, the casting mold comprises a plurality of pin part casting molds with a different pin part casting diameter, a different pin part casting length, or a different pin part casting diameter and a different pin part casting length. This embodiment is a ninth embodiment of the invention, which preferably depends on the eighth embodiment of the invention. In one embodiment of the casting mold, the humeral part casting mold comprises fastening means for inserting a humeral component metal core. This embodiment is a tenth embodiment of the invention, which preferably depends on the eighth or ninth embodiment of the invention.

[0028] In one embodiment of the mold, the partial molds are made of a translucent polymer. This embodiment is an eleventh embodiment of the invention, which preferably depends on one of the eighth to tenth embodiments of the invention.

[0029] In one embodiment of the casting mold, the individual parts, or at least two of the individual parts, of the partial casting mold can be reversibly and detachably connected to one another by locking elements. This embodiment is a twelfth embodiment of the invention, which preferably depends on one of the eighth to eleventh embodiments of the invention.

[0030] A thirteenth embodiment of the invention is a kit for producing an inverse shoulder spacer according to any one of the first to seventh embodiments of the invention, comprising a casting mold according to any one of the eighth to twelfth embodiments of the invention, and a bone cement powder and a monomer liquid for providing a polymethyl methacrylate bone cement dough (PMMA bone cement dough).

[0031] A fourteenth embodiment of the invention is a method for producing an inverse shoulder spacer according to any one of the first to seventh embodiments of the invention using a kit according to the thirteenth embodiment of the invention, comprising the following method steps: a. Providing a polymethyl methacrylate bone cement dough by mixing the bone cement powder with the monomer liquid; b. Filling the humeral component mold, the glenoid component mold, and the post component mold with the polymethyl methacrylate bone cement dough; c. Curing the polymethyl methacrylate bone cement dough to provide the humeral component, the glenoid component, and the post.

[0032] In one embodiment of the method, in a method step d., the pin is secured in one of the pin receptacles of the glenoid component. This embodiment is a fifteenth embodiment of the invention, which preferably depends on the fourteenth embodiment of the invention. General

[0033] In this description, range specifications also include the values ​​referred to as limits. A specification such as "in the range from X to Y" with respect to a quantity A therefore means that A can assume the values ​​X, Y, and values ​​between X and Y. Unilaterally limited ranges such as "up to Y" for a quantity A correspondingly mean the value Y and less than Y.

[0034] Some of the described features are linked to the term "essentially". The term "essentially" is to be understood in such a way that under real conditions and manufacturing techniques, a mathematically exact interpretation of terms such as "superposition", "perpendicular", "diameter" or "parallelism" can never be exact, but only within certain manufacturing error tolerances. For example, "essentially perpendicular axes" enclose an angle of 85 degrees to 95 degrees to one another, and "essentially equal volumes" encompass a deviation of up to 5% by volume. A "device consisting essentially of plastic", for example, comprises a plastic content of >95 to <100% by weight. A "substantially complete filling of a volume B", for example, encompasses a filling of >95 to <100% by volume of the total volume of B.

[0035] Terms such as "proximal" and "distal" merely refer to the spatially opposite ends of the device or other structural units of the device and do not allow any conclusions to be drawn about the orientation relative to a human body, for example, a user of the device. Accordingly, "distal to..." and "proximal to..." or similar formulations merely express the spatial arrangement of two structural units of the device relative to each other.

[0036] For the embodiments described herein, the elements of which “have” or “comprise” a particular feature (e.g. a material), a further embodiment is always contemplated in which the element in question consists solely of the feature, i.e., does not comprise any further components. The word “comprise” or “comprising” is used herein synonymously with the word “have” or “having”. If an element is referred to in the singular in an embodiment, an embodiment is also contemplated in which a plurality of these elements are present. The use of a term for an element in the plural generally also includes an embodiment in which only a single corresponding element is contained.

[0037] Detailed description

[0038] A first subject matter of the invention relates to an inverse shoulder spacer, in particular an articulating inverse shoulder spacer, for temporarily replacing an artificial shoulder joint, comprising a glenoid component which is designed as a convex hemisphere at a distal glenoid component end, a humeral component which has a concave ball receptacle at a proximal humeral component end for receiving the hemisphere of the glenoid component, wherein the hemisphere with the ball receptacle simulates or can simulate an inverse shoulder joint, characterized in that the shoulder spacer has one or more pins, each of which is or can be connected to one of a plurality of concave pin receptacles at a proximal glenoid component end of the glenoid component, such that the shoulder spacer can be fastened via the pin(s) in anchoring holes in a glenoid of a patient.

[0039] The shoulder spacer comprises a glenoid component designed for attachment to a patient's glenoid. The glenoid component is formed as a convex hemisphere at a distal glenoid component end. In the implanted state, this preferably corresponds to the end of the glenoid component that is not directly attached to the glenoid but extends toward the patient's humerus. In one embodiment, the hemisphere and the proximal glenoid component end attached to the patient's glenoid are formed as a single piece. In a further embodiment, the proximal glenoid component end can be formed as a base to which the convex hemisphere is attached, for example, screwed or glued.

[0040] The shoulder spacer further comprises a humeral component. The humeral component has a concave ball socket at a proximal humeral component end, which corresponds to the end of the humeral component facing the patient's glenoid when implanted, for receiving the hemisphere of the glenoid component. Preferably, an outer diameter of the hemisphere substantially corresponds to an inner diameter of the ball socket, so that the hemisphere and the ball socket interact when implanted, i.e., the hemisphere is at least partially received in the ball socket, and together they simulate an inverse shoulder joint. Thus, when the shoulder spacer is implanted, the hemisphere forms a sliding surface with the ball socket of the humeral component as its counterpart.Preferably, the humeral component has a shaft at a distal humeral component end opposite the proximal humeral component end, which shaft can be fastened in the bone canal of the patient's humerus in order to securely connect the humeral component thereto.

[0041] To connect the glenoid component to a patient's glenoid, the shoulder spacer has one or more pins, for example, two, three, four, or five. The pins are designed and intended to be inserted into existing anchoring holes in the patient's glenoid with a pin end and secured there, preferably using a polymethyl methacrylate bone cement. Preferably, the same anchoring holes are used to attach the glenoid component that were already used to attach the primary shoulder prosthesis. Thus, no additional anchoring holes are necessary, which both reduces the effort and preserves as much of the patient's bone substance as possible during the revision of the shoulder prosthesis.

[0042] The pin end, which is not intended for insertion into the anchoring holes in the patient's glenoid, is used to connect the pin(s) to the glenoid component, or at least to connect them when the shoulder spacer is implanted. For this purpose, the glenoid component has a plurality of concave pin receptacles at the proximal end of the glenoid component (in the implanted state, this corresponds to the end of the glenoid component facing the patient's glenoid), for example, at least two, for example six to thirty, preferably ten to twenty, more preferably twelve to eighteen, into which the pins can be inserted with the pin end and secured or can be secured in the pin receptacles. The pin receptacles thus form concave depressions at the proximal end of the glenoid component, which can be used to securely fasten the pins. Fastening in the pin receptacles is preferably achieved using a polymethyl methacrylate bone cement.The multitude of concave pin receptacles allows for versatile and flexible pin attachment, depending on the location of the anchoring holes in the patient's glenoid. The pin receptacles are preferably evenly distributed over the entire surface of the proximal glenoid component end. Thus, the same inverse shoulder spacer according to the invention can be used for different models of reverse shoulder prostheses currently available or to be available in the future.

[0043] The shoulder spacer can be made of different materials or material combinations.

[0044] An embodiment of the shoulder spacer is characterized in that at least the humeral component and the glenoid component comprise a polymethylmethacrylate bone cement or consist of a polymethylmethacrylate.

[0045] Polymethylmethacrylate bone cements have proven effective for knee and hip spacers. They are cost-effective and can be combined with one or more antibiotics, which makes them advantageous for use as spacers. Furthermore, the use of polymethylmethacrylate bone cement as a material for the shoulder spacer allows for simple and rapid fabrication of the shoulder spacer, even during ongoing surgery. The surgeon can consider adding one or more antibiotics to the polymethylmethacrylate during fabrication.

[0046] Preferably, the pin receptacles at least approximately replicate the cross-section of the pins, allowing for simple, quick, and secure attachment. Since the anchoring holes typically have a round cross-section, the pins, and thus the anchoring holes, preferably also have a round cross-section.

[0047] For example, both the pins and the anchoring holes are cylindrical in shape.

[0048] One embodiment of the shoulder spacer is characterized in that the pin receptacles are conical in shape, with an inner circumference of the pin receptacles tapering from a pin receptacle opening towards the distal end of the glenoid component. In this embodiment, the pin receptacles are therefore funnel-shaped, with the pin receptacle opening into which the pins can be inserted having the largest inner circumference, in other words the largest inner diameter, with the inner circumference tapering further and further, i.e. becoming smaller, the further the pin receptacle extends towards the hemisphere. This design allows a certain variation in the orientation of the pins in relation to a longitudinal axis of the glenoid component. This allows the pins attached to the glenoid component to be better adapted to the anchoring holes actually present in the patient's glenoid.For example, the alignment of the pins can be better adapted to a situation in which the anchoring holes in the patient's glenoid do not all have parallel longitudinal axes. The pin receptacles can essentially have the shape of a cone or a truncated cone.

[0049] The conical pin receptacles of this embodiment can have different steepnesses of the outer surfaces, or in other words, side walls, which affects the variability in the alignment of the pins secured therein relative to the longitudinal axis of the glenoid component. The larger the angle enclosed between a cone's longitudinal axis and the outer surface of the conical pin receptacle, the more variable the alignment of the pins. At the same time, the secure attachment of the pins in the pin receptacles becomes more difficult with increasing angles, since the distance between the outer surface and the pin, particularly in the area of ​​the pin receptacle opening, increases with increasing angles.

[0050] One embodiment of the shoulder spacer is characterized in that the conical pin receptacles have a lateral surface that forms an angle in a range of 10-30°, preferably between 15-25°, with a conical longitudinal axis of the pin receptacles. This angle range represents a good compromise between the variability of the pin alignment and the secure and simple attachment of the pins in the pin receptacles.

[0051] The pins can be available in different lengths and / or with different diameters. For example, the pins have a length in a range of 8-45 mm, preferably in a range of 10-40 mm, and a diameter in a range of 2-7 mm, preferably in a range of 2.5-6.6 mm.

[0052] The diameter of the pins can be constant over their entire length. However, the diameter of the pins can also vary along their length. For example, the diameter of the pins can taper from one end to the other, or the pins can have a smaller diameter at both ends than between the two ends. In particular, it may be preferable for the diameter of the pins to taper at the end with which they are secured in the pin receptacles, which can facilitate fastening.

[0053] The pins can all have the same length and the same diameter, in particular the same average diameter. One embodiment of the shoulder spacer is characterized in that the pins have a different diameter, in particular a different average diameter, and / or a different length. This does not mean that all pins have a different length and / or a different diameter, i.e. that each pin is unique, but rather that the pins are available in at least two different lengths and / or with two different diameters. This allows for improved adaptation of the shoulder spacer to anchoring holes present in the patient's glenoid, which may be at different depths and / or with different diameters.

[0054] The pins preferably comprise, like the glenoid component and the humeral component and for the same reasons, a polymethylmethacrylate bone cement or consist of a polymethylmethacrylate bone cement.

[0055] One embodiment of the shoulder spacer is characterized in that the pin(s) have a pin metal core. The pin metal core is preferably located entirely within the pin and is thus completely surrounded by an outer shell, preferably made of a polymethyl methacrylate bone cement. The pin metal core preferably runs substantially parallel to the longitudinal axis of the pin and preferably over at least 70 percent of the total length of the pin. The pin metal core serves to improve the mechanical stability of the pin.

[0056] One embodiment of the shoulder spacer is characterized in that the humeral component has a humeral component metal core to improve mechanical stability, analogous to the preferred pin metal core. Preferably, the humeral component has a shaft, which, when the shoulder spacer is implanted, is secured in the bone canal of the patient's humerus, and the humeral component metal core extends at least partially within the shaft.

[0057] A further subject matter of the invention relates to a casting mold for producing an inverse shoulder spacer according to one of the previously described embodiments of the invention, comprising a humeral casting mold consisting of at least two parts for forming the humeral component, a glenoid casting mold consisting of at least two parts for forming the glenoid component and a pin casting mold consisting of at least two parts for forming the pin or pins.

[0058] A casting mold is a hollow mold that essentially encloses the outer contour of the individual components of the shoulder spacer and can be filled with a suitable material, preferably a polymethyl methacrylate bone cement paste, to create the shoulder spacer through curing. The cured material is preferably removed from the casting mold after curing. Therefore, the casting mold is preferably not part of the shoulder spacer.

[0059] The casting mold comprises a plurality of partial casting molds, preferably a plurality of separate partial casting molds, in particular a humeral partial casting mold for producing the humeral component of the shoulder spacer, a glenoid partial casting mold for producing the glenoid component of the shoulder spacer and at least one pin partial casting mold for producing the pin(s) of the shoulder spacer.

[0060] Each of the partial molds consists of at least two parts, so that the corresponding components and pins can be easily removed from the partial molds after their production. Preferably, each of the partial molds consists of exactly two parts, with the two partial molds being constructed at least mirror-symmetrically to each other, so that each of these parts replicates a substantially mirror-symmetrical longitudinal section of the corresponding component.

[0061] One embodiment of the casting mold is characterized in that it comprises a plurality, i.e., at least two, pin-part casting molds with a different pin-part diameter and / or a different pin-part length. The pin-part casting mold diameter and the pin-part casting mold length each refer to a cavity length or a cavity diameter of the pin-part casting mold, so that these pin-part casting molds enable the production of pins with different diameters and / or lengths.

[0062] The pin part casting mold is preferably suitable for simultaneously producing multiple pins, preferably with different lengths and / or diameters. For example, the pin part casting mold comprises cavities for producing six pins, wherein three of the six pins have a smaller diameter than the remaining six pins. One embodiment of the method is characterized in that the humeral part casting mold comprises fastening means for inserting, in particular for substantially centrally inserting, a humeral component metal core. In one embodiment, the humeral part casting mold has protrusions on its inner wall into which a humeral component metal core can be inserted.

[0063] In a further embodiment, a humeral component metal core has protrusions which can cooperate with an inner wall of the humeral partial casting mold to enable insertion of the humeral component metal core at a desired location within the humeral partial casting mold.

[0064] The casting mold, or each of the partial casting molds, can be made of different materials or material combinations.

[0065] One embodiment of the casting mold is characterized in that the partial casting molds are made of a translucent polymer. This allows for visual inspection of proper filling of the partial casting molds with a suitable material, in particular a polymethyl methacrylate bone cement paste, during the production of the shoulder spacer.

[0066] The individual parts of the partial molds can be connected to one another in different ways to create the partial mold. For example, the individual parts can be connected to one another with screws.

[0067] To enable the simplest and, in particular, reversible connection of the individual parts of the partial casting molds, one embodiment of the casting mold is characterized in that the individual parts of the partial casting molds can be reversibly and detachably connected to one another by locking elements. This also allows for quick release of the parts after the individual components of the shoulder spacer have hardened.

[0068] Another subject matter of the invention relates to a kit for producing an inverse shoulder spacer according to one of the preceding embodiments of the invention, comprising a casting mold according to one of the preceding embodiments of the invention, as well as a bone cement powder and a monomer liquid for preparing a polymethyl methacrylate bone cement paste. The kit allows the production of a shoulder spacer according to the invention comprising a polymethyl methacrylate bone cement or consisting of a polymethyl methacrylate bone cement.

[0069] In one embodiment of the kit, it comprises at least one humeral component metal core and / or one or more pin metal cores for producing humeral components and / or pins reinforced with metal cores.

[0070] Another object of the invention relates to a method for producing an inverse shoulder spacer according to one of the preceding embodiments of the invention by means of a kit according to one of the preceding embodiments of the invention, comprising the following method steps: a. Providing a polymethyl methacrylate bone cement dough by mixing the bone cement powder with the monomer liquid; b. Filling the humeral part casting mold, the glenoid part casting mold, and the pin part casting mold with the polymethyl methacrylate bone cement dough; c. Curing the polymethyl methacrylate bone cement dough to provide the humeral component, the glenoid component, and the pin.

[0071] In process step a., a polymethyl methacrylate bone cement paste is prepared. This preparation can be accomplished by simply mixing the bone cement powder with the monomer liquid, for example, by stirring with a spatula. The polymethyl methacrylate bone cement paste can also be mixed using a so-called pre-pack mixing device. Such devices contain the bone cement powder and the monomer liquid in sterile packaging and allow for simplified, safe, and sterile preparation of the polymethyl methacrylate bone cement paste. Such devices are available, for example, from Heraeus Medical GmbH, Germany, under the name "PALACOS® R+G pro -All-in-One Fixation System™."

[0072] If necessary, one or more antibiotics or other pharmaceutical active ingredients can be added to the polymethyl methacrylate bone cement dough during mixing if these were not already added to the bone cement powder and / or the monomer liquid.

[0073] In a process step b. the partial casting molds are filled with the

[0074] Polymethyl methacrylate bone cement dough. The partial casting molds preferably have a filling opening into which the polymethyl methacrylate bone cement dough is poured. The filling is preferably carried out by discharging the polymethyl methacrylate bone cement dough from a pre-pack mixing device.

[0075] In process step c, the polymethyl methacrylate bone cement mixture hardens. The finished shoulder spacer components can then be removed from the partial casting molds.

[0076] The pin(s) can be attached to the glenoid component at different times during the manufacturing process, particularly in the pin receptacles of the glenoid component. For example, the pin(s) can be attached first to a patient's glenoid and then to the glenoid component.

[0077] One embodiment of the method is characterized in that, in a method step d, the pin is secured in one of the pin receptacles of the glenoid component. Preferably, the pin is secured prior to the pin being secured in an anchoring hole in the patient's glenoid. The pin is preferably secured in the pin receptacle using a polymethyl methacrylate bone cement paste.

[0078] The application mentions polymethyl methacrylate bone cements or polymethyl methacrylate bone cement pastes in several places. A polymethyl methacrylate bone cement paste is understood to be a substance suitable for creating a stable bond between artificial joints, such as hip and knee joints, and bone material in the field of medical technology. Upon curing, a polymethyl methacrylate bone cement paste (PMMA bone cement paste) becomes a polymethyl methacrylate bone cement (PMMA bone cement). PMMA bone cements have long been used in medical applications and date back to the work of Sir Charnley (cf. Charnley, J. Anchorage of the femoral head prosthesis of the shaft of the femur. J. Bone Joint Surg. 1960; 42, 28-30).PMMA bone cements can be produced from a bone cement powder as the first starting component and a liquid starting component, particularly a monomer liquid, as the second starting component. With a suitable composition, the two starting components can be stored separately. When the two starting components are brought into contact, swelling of the polymer components of the bone cement powder creates a plastically deformable bone cement paste. This initiates polymerization of the monomer by radicals. As the monomer polymerization progresses, the viscosity of the bone cement paste increases until it completely hardens.

[0079] A bone cement powder is understood to be a powder comprising at least one particulate polymethyl methacrylate and / or a particulate polymethyl methacrylate copolymer. Examples of copolymers are styrene and / or methyl acrylate. In one embodiment, the bone cement powder can additionally comprise a hydrophilic additive that supports the distribution of the monomer liquid within the bone cement powder. In another embodiment, the bone cement powder can additionally comprise an initiator that initiates the polymerization. In another embodiment, the bone cement powder can additionally comprise an X-ray opaque. In yet another embodiment, the bone cement powder can additionally comprise pharmaceutically active substances, such as antibiotics.

[0080] The bone cement powder preferably comprises, as a hydrophilic additive, at least one particulate polymethyl methacrylate and / or a particulate polymethyl methacrylate copolymer, an initiator, and a radiopaque, or consists of these components. Further preferably, the bone cement powder comprises, or consists of, at least one particulate polymethyl methacrylate and / or a particulate polymethyl methacrylate copolymer, an initiator, a radiopaque, and a hydrophilic additive. Most preferably, the bone cement powder comprises, or consists of, at least one particulate polymethyl methacrylate and / or a particulate polymethyl methacrylate copolymer, an initiator, a radiopaque, a hydrophilic additive, and an antibiotic.

[0081] According to the invention, the particle size of the particulate polymethyl methacrylate and / or the particulate polymethyl methacrylate copolymer of the bone cement powder of the sieve fraction can correspond to less than 150 pm, preferably less than 100 pm.

[0082] According to the invention, the hydrophilic additive can be particulate and / or fibrous. In a further embodiment, the hydrophilic additive can be sparingly soluble, preferably insoluble, in methyl methacrylate. In a further embodiment, the hydrophilic additive can have an absorption capacity of at least 0.6 g of methyl methacrylate per gram of hydrophilic additive. In a further embodiment, the hydrophilic additive can comprise a chemical substance with at least one OH group. It can preferably be provided that the hydrophilic additive has covalently bonded OH groups on its surface. Examples of such preferred hydrophilic additives can be additives selected from the group comprising cellulose, oxycellulose, starch, titanium dioxide, and silicon dioxide, with pyrogenic silicon dioxide being particularly preferred.In one embodiment, the particle size of the hydrophilic additive of the sieve fraction can be less than 100 pm, preferably less than 50 pm, and most preferably less than 10 pm. The hydrophilic additive can be present in an amount of 0.1 to 2.5 wt.% based on the total weight of the bone cement powder.

[0083] According to the invention, the initiator may contain dibenzoyl peroxide or consist of dibenzoyl peroxide.

[0084] According to the invention, a radiopaque agent is understood to be a substance that allows the bone cement to be visible on X-ray images. Examples of radiopaque agents can include barium sulfate, zirconium dioxide, and calcium carbonate. According to the invention, the pharmaceutically active substance can comprise one or more antibiotics and, optionally, added cofactors for the one or more antibiotics. Preferably, the pharmaceutically active substance consists of one or more antibiotics and, optionally, added cofactors for the one or more antibiotics. Examples of antibiotics include gentamicin, clindamycin, and vancomycin.

[0085] According to the invention, the monomer liquid can comprise the monomer methyl methacrylate or consist of methyl methacrylate. In one embodiment, the monomer liquid comprises, in addition to the monomer, an activator dissolved therein, such as N,N-dimethyl-p-toluidine, or consists of methyl methacrylate and N,N-dimethyl-p-toluidine.

[0086] The features disclosed for the inverse shoulder spacer are also disclosed for the mold, the kit and the method and vice versa.

[0087] Figures

[0088] The invention is further illustrated below by means of exemplary figures. The invention is not limited to the figures.

[0089] It shows

[0090] Fig. 1 is a schematic longitudinal section of an exemplary inverse shoulder spacer comprising a glenoid component and a humeral component,

[0091] Fig. 2 the shoulder spacer from Figure 1 in a perspective front view,

[0092] Fig. 3 the shoulder spacer from Figures 1 and 2 in a perspective

[0093] side view,

[0094] Fig. 4 shows an enlarged section of the glenoid component from Figures 1 to 3 in a schematic longitudinal section,

[0095] Fig. 5 is a schematic longitudinal section of a glenoid part casting mold of a casting mold for producing the shoulder spacer from Figures 1 to 4,

[0096] Fig. 6 is a schematic longitudinal section of a humeral part casting mold of a casting mold for producing the shoulder spacer from Figures 1 to 4,

[0097] Fig. 7 is a schematic cross-section of a pin part mold of a mold for producing the shoulder spacer from Figures 1 to 4, and

[0098] Fig. 8 is a schematic plan view of the pin part casting mold from Figure 7.

[0099] Description of the characters

[0100] Figure 1 shows a schematic longitudinal section of an exemplary inverse shoulder spacer 100. The shoulder spacer 100 has a glenoid component 110, which is formed at its distal glenoid component end as a concave hemisphere 115. Furthermore, the shoulder spacer 100 has a humeral component 120 comprising a concave ball receptacle 125 for receiving the hemisphere 115 of the glenoid component 110. The hemisphere 115, together with the ball receptacle 125, forms an inverse shoulder joint in the position shown in Figure 1, just as provided in the implanted state of the shoulder spacer 100.

[0101] At a proximal glenoid component end opposite the hemisphere 115, the glenoid component 110 has a plurality of pin receptacles 140 (shown only as an example), in particular conical pin receptacles 140. Pins 130 are secured in selected pin receptacles 140, which serve to secure the shoulder spacer 100 in anchoring holes in the glenoid of a patient. The number, position, and orientation of the pins 130 preferably depend on existing anchoring holes in the patient's glenoid, originating from a primary shoulder prosthesis. In the embodiment shown, the pins 130 are secured in the pin receptacles 140 using a polymethyl methacrylate bone cement (not shown).

[0102] To improve the mechanical stability of the shoulder spacer 100, in particular of the humeral component 120, a humeral component metal pin 121 is embedded in the humeral component 120, which extends over a large part of the length of the humeral component 120, in particular a shaft 122 of the humeral component. The shaft 122 serves to secure the humeral component 120 in a bone canal of the patient's humerus.

[0103] In the embodiment shown, the shoulder spacer 100 is made of a polymethylmethacrylate bone cement, with the humeral component metal core 121 being made of stainless steel.

[0104] Figure 2 shows the shoulder spacer 100 from Figure 1 in a perspective front view of the glenoid component 100. In the view shown, it can be seen that the glenoid component 110 has a total of seventeen pin receptacles 140 (shown only as an example), which are distributed essentially over the entire proximal glenoid component end. It can also be seen that the shoulder spacer 100 has a total of five pins 130, with the pins 130 having two different diameters. The central pin 130 has a larger diameter than the four pins 130 attached to the edge of the glenoid component 110. The diameter of the pins 130 depends on the patient's anchoring holes and is shown here only as an example in the configuration shown.

[0105] Figure 3 shows the shoulder spacer 100 from Figures 1 and 2 in a perspective side view for a better overview. To avoid repetition, reference is made to the description of the previous figures for a description of the individual features.

[0106] Figure 4 shows an enlarged section of the glenoid component 110 from Figures 1 to 3 in a schematic longitudinal section. The section shows in particular the proximal glenoid component end with two pin receptacles 140, wherein a pin 130 is fastened in one of the two pin receptacles 140. The pin receptacles 140 (all pin receptacles, not just the two shown) have a pin receptacle opening 141, which serves to insert a pin 130 into the pin receptacles 140. In the embodiment shown, the pin receptacles 140 are conical in shape. This means that a lateral surface 142, in other words the lateral wall, of the pin receptacles 140 forms an angle 144 with a longitudinal axis 143 of the pin receptacles 140 (only as an example on the pin receptacle

[0107] 140 (shown without pin 130) and thus an inner circumference of the pin receptacles 140 tapers from the pin receptacle opening 141 towards the hemisphere 115 (see Figure 1). In the embodiment shown, the angle 144 is 20°. The pins 130, however, have a smaller diameter than the pin receptacle 140, at least at the pin receptacle openings.

[0108] 141 and up to a certain depth of the pin receptacles 140. This allows a deflection of a longitudinal axis of the pins 130 from the longitudinal axis of the pin receptacles and thus more flexibility in fastening the pins 130 in the pin receptacles 140, as in the pin receptacle 140 shown in Figure 4 filled with a pin 130.

[0109] Figure 5 shows a schematic longitudinal section of a glenoid partial casting mold 210 for producing the glenoid component 110 of the shoulder spacer 100 from Figures 1 to 4. The glenoid partial casting mold 210, together with a humeral partial casting mold 220 (see Figure 6) and a pin partial casting mold 230 (see Figure 7), forms a casting mold for producing the shoulder spacer 100 from Figures 1 to 4.

[0110] In the embodiment shown, the glenoid partial casting mold 210 is constructed of two parts that are reversibly and detachably connected to one another by locking elements 240. One of these parts essentially replicates the hemisphere 115 (see Fig. 1), and the other essentially replicates the proximal glenoid component end with the pin receptacles 140 (see Fig. 1). The glenoid partial casting mold 210 can be filled with a suitable material, preferably a polymethyl methacrylate bone cement paste, which then hardens to form the glenoid component 110 of the shoulder spacer 100. The locking elements 240 allow for simple and quick opening of the glenoid partial casting mold 210 for removal of the glenoid component 110.

[0111] Figure 6 shows the humeral partial casting mold 220, a second partial casting mold of the casting mold for producing the shoulder spacer 100, in particular for producing the humeral component 120, from Figures 1 to 4, in a schematic longitudinal section. The humeral partial casting mold 220 comprises three parts, one part essentially simulating the ball receptacle 125 (see Figure 1). The two remaining parts of the humeral partial casting mold 220 essentially form the shaft 122 (see Figure 1), with all parts being connected to one another by locking elements 240 (shown only as an example). Within the humeral partial casting mold 220, the humeral component metal core 121 is accommodated to be coated with a suitable material, preferably a polymethyl methacrylate bone cement paste, which then cures to provide the humeral component 120 of the shoulder spacer 100.The locking elements 240 allow easy and quick opening of the humeral casting mold 220 for removal of the humeral component 120.

[0112] Figure 7 shows, in a schematic cross-section, the pin-part casting mold 230, a third partial casting mold of the casting mold for producing the shoulder spacers 100, in particular for producing the pins 130, from Figures 1 to 4. The pin-part casting mold 230 comprises two parts, which are reversibly connected to one another by locking elements 240. The two parts together form the pins. One of the parts comprises a filling opening 250 for filling the pin-part casting mold 230 with a suitable material, in particular a polymethyl methacrylate bone cement dough, for producing the pins 130 (see Figure 1). Each of the partial casting molds 210, 220, 230 comprises such a filling opening 250, even if it is not shown in Figures 5 and 6.

[0113] The pin part casting mold 230 is used to produce pins 130 with different diameters, in particular different average diameters. Pins with a smaller diameter can be produced in the upper part of the pin part casting mold 230, and pins with a larger diameter can be produced in the lower part.

[0114] Figure 8 shows the pin part casting mold 230 from Figure 7 in a schematic plan view. Figure 8 shows that the pin part casting mold 230 is suitable for the simultaneous production of a total of six pins, three pins with a smaller diameter and three pins with a larger diameter.

[0115]

[0116] 100 inverse shoulder spacer

[0117] 110 Glenoid component

[0118] 115 convex hemisphere

[0119] 120 Humeral component

[0120] 121 Humeral component metal core

[0121] 122 shaft

[0122] 125 concave ball mount

[0123] 130 pen

[0124] 140 pin holder

[0125] 141 pin receptacle opening

[0126] 142 lateral surface

[0127] 143 Cone longitudinal axis

[0128] 144 angles

[0129] 210 Glenoid partial casting mold

[0130] 220 Humerus partial casting mold

[0131] 230 pin part casting mold

[0132] 240 locking elements

[0133] 250 filling opening

Claims

CLAIMS 1 . Inverse shoulder spacer (100) for temporarily replacing an artificial shoulder joint, comprising a glenoid component (110) which is designed as a convex hemisphere (115) at a distal glenoid component end, a humeral component (120) which has a concave ball receptacle (125) at a proximal humeral component end for receiving the hemisphere (115) of the glenoid component (110), wherein the hemisphere (115) with the ball receptacle (125) simulates or can simulate an inverse shoulder joint, characterized in that the shoulder spacer (100) has one or more pins (130), each of which is connected or connectable with a pin end to one of a plurality of concave pin receptacles (140) at a proximal glenoid component end of the glenoid component (110), so that the shoulder spacer (100) can be inserted into the proximal glenoid component end via the pin(s) (130). anchoring holes in a patient's glenoid.

2. Inverse shoulder spacer (100) according to claim 1, wherein the humeral component (120) and the glenoid component (110) comprise or consist of a polymethylmethacrylate bone cement.

3. Inverse shoulder spacer (100) according to claim 1 or 2, wherein the pin receptacles (140) are conical in shape, wherein an inner circumference of the pin receptacles (140) tapers from a pin receptacle opening (141) towards the distal glenoid component end.

4. Inverse shoulder spacer (100) according to claim 3, wherein the conical pin receptacles (140) have a lateral surface (142) which forms an angle (144) in a range of 10-30 with a conical longitudinal axis (143) of the pin receptacle 0 includes.

5. Inverse shoulder spacer (100) according to one of the preceding claims, wherein the pins (130) have a different diameter and / or a different length.

6. Inverse shoulder spacer (100) according to one of the preceding claims, wherein the pin or pins (130) have a pin metal core.

7. Inverse shoulder spacer (100) according to one of the preceding claims, wherein the humeral component (120) has a humeral component metal core (121).

8. A casting mold for producing an inverse shoulder spacer (100) according to one of claims 1 to 7, comprising a humeral partial casting mold (220) consisting of at least two parts for forming the humeral component (120), a glenoid partial casting mold (210) consisting of at least two parts for forming the glenoid component (110) and a pin partial casting mold (230) consisting of at least two parts for forming the pin (130) or pins (130).

9. Casting mold according to claim 8 comprising a plurality of pin part casting molds (230) with a different pin part casting mold diameter and / or a different pin part casting mold length.

10. A casting mold according to claim 8 or 9, wherein the humeral part casting mold comprises fastening means for inserting a humeral component metal core.

11. A casting mold according to any one of claims 8 to 10, wherein the partial casting molds consist of a translucent polymer.

12. Casting mold according to one of claims 8 to 11, wherein the individual parts of the partial casting molds (210, 220, 230) can be reversibly releasably connected to one another by locking elements (240).

13. Kit for producing an inverse shoulder spacer (100) according to one of claims 1 to 7, comprising a casting mold according to one of claims 8 to 12 and a bone cement powder and a monomer liquid for providing a polymethyl methacrylate bone cement dough.

14. A method for producing an inverse shoulder spacer (100) according to any one of claims 1 to 7 by means of a kit according to claim 13, comprising the following method steps: a. Providing a polymethyl methacrylate bone cement dough by Mixing the bone cement powder with the monomer liquid; b. Filling the humeral component mold (220), the glenoid component mold (210), and the post component mold (230) with the polymethyl methacrylate bone cement paste; c. Curing the polymethyl methacrylate bone cement paste to prepare the humeral component (120), the glenoid component (110), and the post (130).

15. The method according to claim 14, wherein in a method step d. the pin (130) is fastened in one of the pin receptacles (140) of the glenoid component (110).

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