Artificial socket for a joint implant and method for manufacturing such a socket

Abstract

Artificial socket (10) for a joint implant, wherein the socket (10) comprises a cup-shaped base body (12) with a rim (20) and a pole (24), and wherein the base body (12) has engagement elements (36) projecting towards the bone on an outer surface (14) facing a bone in the insertion position, wherein the base body (12) is coated at least partially on the outer surface (14) with an osteointegrative coating (56), wherein the engagement elements (36) have a first side surface (48) facing a plane (32) defined by the rim (20), and a second side surface (50) facing the bone, characterized in that the coating (56) on the first side surface (48) is thinner than on the second side surface (50) and / or that the engagement elements (36) are coated at least partially in such a way thatthat the coating (56) extends beyond the coating (56) on the first side surface (48) at its free ends in the direction of a plane (32) defined by the edge (20) and the engagement elements (36) with the coating (56) applied to them form an undercut (58) in a direction transverse to the plane (32).

Description

[0001] The invention relates to an artificial socket for a joint implant, wherein the socket comprises a cup-shaped base body with a rim and a pole, and wherein the base body has engagement elements projecting towards the bone on an outer surface facing a bone in the insertion position, wherein the base body (12) is coated at least partially on the outer surface (14) with an osteointegrative coating (56), wherein the engagement elements (36) have a first side surface (48) facing a plane (32) defined by the rim (20), and a second side surface (50) facing the bone.

[0002] Furthermore, the invention relates to a method for manufacturing an artificial socket of a joint implant, comprising the following process steps: - Providing a bowl-shaped base body with a rim and a pole; - Forming projecting engagement elements on an outer surface of the base body facing a bone in the insertion position, wherein the engagement elements are formed with a first side surface facing a plane defined by the edge, and a second side surface facing the bone; and - Coat at least one section of the outer surface with an osteointegrative coating.

[0003] An artificial socket of the type mentioned above, a socket implant, can be used in joint implants, specifically in hip joint endoprostheses, which consist of a socket and a femoral stem prosthesis that interacts with it. During implantation, the socket is positioned in an insertion position and, with force applied, inserted pole-first into a previously prepared bone, for example, the acetabulum in the case of a hip joint prosthesis. On the outer surface facing the bone, the socket has engagement elements that protrude from the base body. These engagement elements ensure a secure fit of the socket in the bone and can, for this purpose, engage with it. Such a fit is referred to as an "interference fit," in which the engagement elements typically extend beyond the nominal contour of the recess adapted to the bone.

[0004] The socket can be a joint socket with an articular surface on its inner surface (facing away from the outer surface) that interacts with a corresponding articular surface on another implant component. Alternatively, the socket could be an outer socket of an implant component, into the space enclosed by the base body of which an inner socket is inserted and firmly connected. In this case, the inner socket can include the aforementioned articular surface for interaction with the corresponding articular surface of the other implant component.

[0005] The pan defines a pole, and it may also be provided that the base body has an opening at the pole, for example for connection with an insertion tool for the pan.

[0006] A cementless acetabular implant is known from DE 697 17 586 T2. US 5 571 200 A deals with an acetabular cup as well as a method and a tool for its implantation. A cementless acetabular cup is described in US 5 358 532 A.

[0007] The object of the present invention is to provide a generic pan which can be anchored to the bone in a better way.

[0008] This problem is solved according to the invention in a pan of the type mentioned at the outset by the fact that the coating on the first side surface is thinner than on the second side surface and / or that the engagement elements are at least partially coated in such a way that the coating at their free ends extends beyond the coating on the first side surface in the direction of a plane defined by the edge and the engagement elements with the coating applied thereto form an undercut in a direction transverse to the plane.

[0009] In the pan according to the invention, primary stability relative to the bone can be achieved by bringing the engagement elements into contact with the bone, thus creating a press fit of the pan against the bone. Furthermore, the pan has a coating on at least a section of its outer surface. The coating is osteointegrative and allows for secondary stability of the pan relative to the bone. In this context, "osteointegrative" can be understood to mean, in particular, that the coating promotes the ingrowth of bone or bone material to the pan and facilitates this process, especially compared to a pan with a base and engagement elements without a coating. For this purpose, the coating can preferably have a porous structure, at least on the side facing the bone, to create a large surface area facing the bone.The increased surface area facilitates the ingrowth of bone or bone material, thereby promoting a firm hold of the acetabular cup on the bone. In practice, it has been shown that the combination of a macrostructure formed by the engagement elements with the microstructure formed by the coating ensures a particularly reliable fit of the acetabular cup to the bone. In this context, "macrostructure" and "microstructure" can be understood to mean, in particular, that the roughness resulting from the engagement elements exceeds the roughness of the outer surface resulting from the coating. According to the invention, the engagement elements have a first side surface facing a plane defined by the edge and a second side surface facing the bone.In this context, this can be understood to mean, in particular, that the engagement elements have a top surface (second side surface) facing the viewer from the outside and a bottom surface (first side surface) facing away from the viewer. The first and second side surfaces can be directly or indirectly connected to each other and oriented at an angle relative to each other. The engagement elements can have at least partially first side surfaces that are aligned in a plane parallel to the plane defined by the edge and thus in a plane perpendicular to the polar axis. The lines of intersection of the first and / or the second side surface with the base body are preferably aligned in a plane perpendicular to the polar axis and can run along a degree of latitude of an ellipsoid defined by the base body.Furthermore, according to the invention, the coating on the first side surface is thinner than on the second side surface, and / or the engagement elements are at least partially coated such that the coating at their free ends projects beyond the coating on the first side surface in the direction of a plane defined by the edge, and the engagement elements with the coating applied thereto form an undercut in the direction transverse to this plane. The engagement elements with the coating applied thereto make it possible to form an undercut in a manufacturingly simple manner. For this purpose, for example, as in the last advantageous embodiment of the pan, the coating on the first side surface is thinner than on the second side surface, so that a bead-like overhang of the coating is formed in the area of ​​the free ends of the engagement elements, projecting in the direction of the plane defined by the edge.The undercut allows for a particularly reliable fit of the socket by utilizing primary and secondary stability on the bone.

[0010] The coating is preferably osteoconductive and suitable for stimulating the growth of bone or bone material.

[0011] It proves advantageous if the base body is coated with the coating at least on a section of the outer surface provided with engagement elements. The primary stability achievable by the engagement elements can thus be specifically supplemented with secondary stability by the coating covering them.

[0012] It is advantageous if the base body is completely or substantially completely coated on the outside to allow for even better anchoring of the socket to the bone.

[0013] Preferably, the coating comprises or consists of titanium and / or calcium phosphate. Practical experience has shown that porous titanium and / or calcium phosphate coatings exhibit an osteointegrative effect.

[0014] The layer can be applied to the base body, for example, using a plasma coating process, which will be discussed in more detail below.

[0015] The average thickness of the coating is, for example, approximately 200 µm to approximately 500 µm, preferably approximately 350 µm.

[0016] It may be provided, in particular, that the coating has varying thicknesses in different sections. "Various thicknesses" in this context refers to an average thickness of the coating, taking into account variations in its thickness due to porosity. It may be provided that sections of the coating have different average thicknesses despite having the same or substantially the same porosity.

[0017] It is advantageous if the base body is free of engagement elements in a pole region extending across the pole. Engagement elements in the area of ​​the pole or the region extending across the pole are usually of less importance for a press fit on the bone. This embodiment therefore simplifies the manufacture of the cup.

[0018] It can be provided, for example, that the base body is free of intervening elements from the pole over an angle of approximately 30° to approximately 50°, with respect to a polar axis of an ellipsoid defined by the base body. In this context, this can be understood to mean, in particular, that the base body is free of intervening elements from the pole to approximately the 60th degree of latitude or to approximately the 40th degree of latitude, with respect to an ellipsoid defined by the base body. The base body can, for example, form a section of a sphere, in particular a hemisphere, or a section of an ellipsoid that is flattened at the pole with respect to a spherical contour. A coordinate system can be adapted to the ellipsoid, in particular the sphere, with an equator located at or near the edge and a pole coinciding with the pole. From approximately the 40th degree of latitude to the pole, up to approximately the 60th degree of latitude...In the present embodiment, the base body can have a pole area free of engagement elements, extending from the latitude to the pole.

[0019] It is advantageous if engagement elements are arranged on the outer circumference of the base body. In this case, this can be understood to mean, in particular, that engagement elements are arranged on the radial side at a distance from the pole. For example, the base body has areas equipped with engagement elements at latitudes approximately less than the 60th degree or less than the 40th degree. The engagement elements arranged on the outer circumference ensure high primary stability of the acetabular cup on the bone.

[0020] Advantageously, the intervention elements extend to the edge or substantially to the edge. Intervention elements positioned at or near the edge enable a press fit of the acetabulum with the bone at or near the edge.

[0021] It is advantageous if the engagement elements are arranged on the base body in several circumferential rows, each defining a plane perpendicular to a polar axis defined by the base body. The engagement elements can circumferentially around the outer surface with respect to the polar axis. Each row runs in a plane perpendicular to the polar axis, and thus, in a sense, along a circle of latitude of an ellipsoid defined by the base body. Adjacent rows can have identical or different spacings. Within a row, the engagement elements are preferably identical in design.

[0022] It may be provided that circumferential grooves are formed between the rows on the base body.

[0023] It is advantageous if the engagement elements are arranged in several rows on the base body, each row defining a plane containing a polar axis defined by the base body. The engagement elements can run in planes containing the polar axis, essentially along meridians of an ellipsoid defined by the base body. In the circumferential direction of the polar axis, adjacent rows preferably have identical spacings from one another.

[0024] The foregoing explanations show that the intervention elements can be arranged on the outside, in particular in the form of a net or grid structure.

[0025] It proves advantageous if the engagement elements are designed differently depending on their position on the base body.

[0026] For example, it can be provided that the height of the engagement elements relative to the base body decreases with decreasing distance from the pole. In this context, this can be understood to mean, in particular, that the engagement elements project further from the base body the greater their distance from the pole. The height of the engagement elements can decrease monotonically and / or continuously with decreasing distance from the pole.

[0027] Furthermore, it is advantageous if the length of the intervention elements, relative to a direction from the edge to the pole, increases in the direction of the pole. In this case, this can be interpreted in particular as meaning that the intervention elements cover a larger number of latitudes of an ellipsoid defined by the base body as their distance from the pole decreases. The length of the intervention elements can increase monotonically and / or continuously with their decreasing distance from the pole.

[0028] It proves advantageous if, in a direction from the edge to the pole, the first lateral surface is shorter than the second. This allows, in particular, the formation of barbed projections with the intervention elements to ensure reliable anchoring of the acetabular cup to the bone.

[0029] Preferably, the engagement elements do not form an undercut in the direction transverse to the plane, thus simplifying the manufacture of the pan. In the direction transverse to the plane defined by the edge, the engagement elements can be designed without undercuts. The undercut can be easily created during manufacturing by means of the coating.

[0030] An advantageous embodiment of the pan according to the invention comprises engagement elements that are truncated pyramid-shaped, truncated cone-shaped, or prismatic. The engagement elements can taper from the base body, be free of points, and be flattened at their ends. The engagement elements can comprise discrete, mutually angled side surfaces, for example, the first and second side surfaces mentioned above. The side surfaces can be planar.

[0031] The problem set out at the outset is solved according to the invention in a method of the type described at the outset by coating the engagement elements on the first side surface with a thinner coating than on the second side surface and / or by coating the engagement elements at least partially in such a way that the coating at the free ends of the engagement elements projects beyond the coating on the first side surface in the direction of a plane defined by the edge and the engagement elements with the coating applied thereon form an undercut in the direction transverse to the plane.

[0032] It is advantageous to use a plasma coating process. For example, the substrate is placed in a reaction chamber where a plasma is ignited. The coating material(s) can be vaporized in the reaction chamber or introduced there using a carrier gas.

[0033] Titanium and / or calcium phosphate are preferably used as the material for the coating.

[0034] Specifically, when using calcium phosphate for the coating, a different coating process than plasma coating may be employed. For example, a calcium phosphate coating can be applied using an electrolytic coating process.

[0035] It is possible for the base body to be coated with more than one coating. For example, it is conceivable to coat the base body with a titanium-based first coating and then apply a calcium phosphate-based second coating on top of this first coating.

[0036] Advantageously, the base body is coated at least on one section of the outside that is provided with engagement elements.

[0037] The base body can advantageously be completely or substantially completely coated on the outside.

[0038] It proves advantageous if the outer surface is coated with different thicknesses in sections.

[0039] The engagement elements are preferably formed by an abrasive manufacturing process, in particular by turning and / or milling the base body.

[0040] Advantageously, no interlocking elements are formed in a polar region of the base body extending across the pole, for example, extending from the pole at an angle of approximately 30° to approximately 50° with respect to a polar axis of an ellipsoid defined by the base body. The base body can be formed from the pole to approximately the 60th degree of latitude or to approximately the 40th degree of latitude without interlocking elements, relative to an ellipsoid defined by the base body.

[0041] Preferably, engagement elements are formed on the outer circumference of the base body, preferably up to the edge or substantially up to the edge.

[0042] The engagement elements can be formed in several circumferential rows, each defining a plane perpendicular to a polar axis defined by the base body. Circumferential grooves can be formed between the rows on the base body, for example by turning.

[0043] Furthermore, the engagement elements can be formed on the base body in multiple rows, each defining a plane containing a polar axis defined by the base body. For example, the rows are formed by milling the base body from the pole to the edge and / or vice versa.

[0044] Advantageously, the engagement elements are designed in such a way that they are shaped differently depending on their position on the base body, preferably that the height of the engagement elements relative to the base body decreases with decreasing distance to the pole.

[0045] The length of the intervention elements, in a direction from the edge to the pole, can increase in the direction of the pole.

[0046] It is advantageous if the intervention elements are designed with a first side surface facing a plane defined by the edge, and a second side surface facing the bone.

[0047] Preferably, the first side surface is made shorter than the second side surface, in a direction from the edge to the pole.

[0048] It proves advantageous if the engagement elements on the first side surface are coated with a thinner coating than on the second side surface.

[0049] In particular, it is advantageous if the engagement elements are at least partially coated in such a way that the coating at the free ends of the engagement elements extends beyond the coating on the first side surface in the direction of a plane defined by the edge, and the engagement elements with the coating applied to them form an undercut in the direction perpendicular to the plane.

[0050] Advantageously, the engagement elements are manufactured in such a way that they (uncoated) do not form an undercut in the direction perpendicular to the plane.

[0051] The intervention elements can be formed in particular as truncated pyramids, truncated cones or prismatic shapes.

[0052] The foregoing description thus includes in particular the exemplary embodiments of an artificial pan or a method for producing an artificial pan, defined below in the form of numbered sentences: 1. Artificial socket for a joint implant, wherein the socket (10) comprises a cup-shaped base body (12) with a rim (20) and a pole (24), and wherein the base body (12) has engagement elements (36) projecting towards the bone on an outer surface (14) facing a bone in the insertion position, characterized in that the base body (12) is coated at least partially on the outer surface (14) with an osteointegrative coating (56). 2. Pan according to sentence 1, characterized in that the base body (12) is coated with the coating (56) at least on a section of the outer surface (14) provided with engagement elements (36). 3. Pan according to sentence 1 or 2, characterized in that the base body (12) is completely or substantially completely covered with the coating (56) on the outside (14). 4. Pan according to one of the preceding sentences, characterized in that the coating (56) comprises or consists of titanium and / or calcium phosphate. 5. Pan according to one of the preceding sentences, characterized in that the coating (56) is of different thicknesses in sections. 6. Pan according to one of the preceding sentences, characterized in that the base body (12) is free of engagement elements (36) at a pole area (42) extending over the pole (24). 7. Pan according to sentence 6, characterized in that the base body is free of engagement elements (36) starting from the pole (24) over an angle of approximately 30° to approximately 50°, with respect to a polar axis (34) of an ellipsoid defined by the base body (12). 8. Pan according to one of the preceding sentences, characterized in that engagement elements (36) are arranged on the outer circumference of the base body (12). 9. Pan according to one of the preceding sentences, characterized in that the engagement elements (36) extend to the edge (20) or substantially to the edge (20). 10. Pan according to one of the preceding sentences, characterized in that the engagement elements (36) are arranged on the base body (12) in several circumferential rows (38), each defining a plane perpendicular to a polar axis (34) defined by the base body (12). 11. Pan according to sentence 10, characterized in that circumferential grooves (44) are formed between the rows (38) on the base body (12). 12. Pan according to one of the preceding sentences, characterized in that the engagement elements (36) are arranged on the base body (12) in several rows (46), each defining a plane containing a polar axis (34) defined by the base body (12). 13. Pan according to one of the preceding sentences, characterized in that the engagement elements (36) are designed differently depending on their position on the base body (12). 14. Pan according to sentence 13, characterized in that the height of the engagement elements (36) relative to the base body (12) decreases with decreasing distance to the pole (24). 15. Pan according to sentence 13 or 14, characterized in that the length of the engagement elements (36), in relation to a direction from the edge (20) to the pole (24), increases in the direction of the pole (24). 16. Pan according to one of the preceding sentences, characterized in that the engagement elements (36) have a first side surface (48) facing a plane (32) defined by the edge (20), and a second side surface (50) facing the bone. 17. Pan according to sentence 16, characterized in that, with respect to a direction from edge (20) to pole (24), the first side surface (48) is shorter than the second side surface (50). 18. Pan according to sentence 16 or 17, characterized in that the coating (56) on the first side surface (48) is thinner than on the second side surface (50). 19. Pan according to one of sentences 16 to 18, characterized in that the engagement elements (36) are at least partially coated such that the coating (56) extends beyond the coating (56) on the first side surface (48) at their free ends in the direction of a plane (32) defined by the edge (20) and the engagement elements (36) with the coating (56) applied thereto form an undercut (58) in a direction transverse to the plane (32). 20. Pan according to sentence 19, characterized in that the engagement elements (36) do not form an undercut (58) in the direction transverse to the plane (32). 21. Pan according to one of the preceding sentences, characterized in that the engagement elements (36) are truncated pyramidal, truncated conical or prismatic in shape. 22. Method for manufacturing an artificial socket for a joint implant, comprising the following process steps: - Providing a bowl-shaped base body with a rim and a pole; - Formation of protruding intervention elements on an outer surface of the base body facing a bone in the insertion position; and - Coat at least one section of the outer surface with an osteointegrative coating. 23. Method according to sentence 22, characterized in that a plasma coating process is used for coating. 24. Method according to sentence 22 or 23, characterized in that titanium and / or calcium phosphate is used as the material for the coating. 25. Method according to one of sentences 22 to 24, characterized in that the base body is coated at least on a section of the outside provided with engagement elements. 26. Method according to one of sentences 22 to 25, characterized in that the base body is completely or substantially completely coated on the outside. 27. Method according to one of sentences 22 to 26, characterized in that the outer surface is coated with different thicknesses in sections. 28. Method according to one of sentences 22 to 27, characterized in that the engagement elements are formed by turning and / or milling the base body. 29. Method according to one of sentences 22 to 28, characterized in that no engagement elements are formed on a pole region of the base body extending over the pole. 30. Method according to one of sentences 22 to 29, characterized in that engagement elements are formed on the outer circumference of the base body, preferably up to the edge or substantially up to the edge. 31. Method according to one of sentences 22 to 30, characterized in that the engagement elements are designed in such a way that they are designed differently depending on their position on the base body, preferably that the height of the engagement elements with respect to the base body is designed to decrease with decreasing distance of the engagement elements to the pole. 32. Method according to one of sentences 22 to 31, characterized in that the engagement elements are formed with a first side surface facing a plane defined by the edge, and a second side surface facing the bone. 33. Method according to sentence 32, characterized in that the engagement elements on the first side surface are coated with a thinner coating than on the second side surface. 34. Method according to sentence 32 or 33, characterized in that the engagement elements are at least partially coated such that the coating at the free ends of the engagement elements extends beyond the coating on the first side surface in the direction of a plane defined by the edge and the engagement elements with the coating applied thereon form an undercut in the direction transverse to the plane.

[0053] The following description of preferred embodiments of the invention, in conjunction with the drawing, serves to explain the invention in more detail. The drawings show: Fig. 1: a perspective view of a first preferred embodiment of a pan according to the invention, comprising a base body and a coating applied thereto; Fig. 2: a perspective view of the basic shape of the pan made of Fig. 1; Fig. 3: a section-by-section side view of the basic body made of Fig. 2; Fig. 4: a section-by-section longitudinal view of the pan made of Fig. 1 and Fig. 5: an enlarged view of detail A in Fig. 4.

[0054] Fig. Figure 1 shows a perspective view of an implant in the form of a preferred embodiment of an artificial socket designated by reference numeral 10. The socket 10 is an outer socket of a hip component of a hip joint. The socket 10 can be rigidly connected to an inner socket of the hip component, which is not shown in the drawing. The inner socket can comprise an articular surface that interacts with a correspondingly designed articular surface of a femoral component of a hip joint.

[0055] The socket comprises a cup-shaped base body 12 in the form of a hollow cap, which has an outer surface 14 and an inner surface 16. In the insertion position of the socket 10, the outer surface 14 faces a bone (not shown in the drawing) in which the socket 10 is anchored. Before insertion of the socket 10, a recess with a typically spherical contour is adapted to the bone (the acetabulum in the case of a hip socket), which is Fig. 5 is symbolized by a solid line 18.

[0056] The base body 12 defines an ellipsoid and has a rim 20 located proximally, which encloses an insertion opening 22 for inserting the inner cup (not shown). The rim is located approximately at or defines the equator of the ellipsoid. Distally, the base body 12 defines a pole 24, at which, in this case, an opening 26 is formed. A connecting device 28 is arranged at the opening 26, via which an insertion tool (not shown in the drawing) can be connected to the cup 10. The opening 26 can be closed by means of a closing element 30.

[0057] The boundary 20 defines a plane 32, perpendicular to which a polar axis 34 of the base body 12 is aligned. The base body 12 defines an ellipsoid, which can be a spherical ellipsoid. In the present case, however, the base body 12 defines an ellipsoid compressed along the polar axis 34, which is particularly evident in Fig. 5 can be seen by comparison with the spherical contour 18. Around the pole 24, the base body 12 is compressed and thus flattened.

[0058] The base body 12 has a plurality of engagement elements 36 for engaging the bone, projecting from the outer surface 14 towards the bone. The engagement elements 36 are arranged in rows 38, each defining a plane perpendicular to the polar axis 34. Within a row 38, the identical engagement elements 36 encircle the entire outer surface 14. There are a total of eleven rows 38. On the proximal side, a first row 38 is arranged near the edge 20. On the distal side, a row 38 is arranged approximately in the region of the 40th to 50th degree of latitude of the ellipsoid defined by the base body 12.

[0059] Adjacent rows 38 are spaced approximately the same distance apart and extend over several degrees of latitude of the ellipsoid. The engagement elements 36 in the six rows 38 facing the edge 20 cover approximately the same number of latitudes. In contrast, the engagement elements 36 in the five rows 38 facing the pole 24 are somewhat longer in the direction from the edge 20 to the pole 24. Accordingly, the distance between the rows 38 increases in the direction of the pole 24. Furthermore, the length of the engagement elements 36 increases in the direction from the edge 20 to the pole 24.

[0060] No engagement elements 36 are arranged on the rim 20 itself, which forms a circumferential bead 40. The bead 40 can serve, for example, for holding and facilitating the manufacture of the pan 10. Furthermore, the bead 40 can be engaged, for example, when inserting the pan 10 or during a service using an insertion or removal tool. It is also conceivable that an inner pan engages the bead 40.

[0061] Furthermore, no engagement elements 36 are arranged on the base body 12 in a polar region 42 extending over the pole 24. The polar region 42 extends from the pole 24 to approximately the 40th to 50th degree of latitude of the ellipsoid defined by the base body 12. The base body 12 is free of engagement elements 36 over an angle with respect to the polar axis 34 of approximately 40° to approximately 50°.

[0062] Between adjacent rows 38, circumferential grooves 44 are formed on the base body 12 in planes perpendicular to the pole axis 34.

[0063] The engagement elements 36 are further arranged in rows 46 on the outer surface 14, each defining a plane containing the polar axis 34. Accordingly, the engagement elements 36 extend in the rows 46 along longitudes of the ellipsoid defined by the base body 12. There are approximately 60 to approximately 80 rows 46 in total, each extending over a few longitudes, with the rows 46 being equidistant from each other on the base body 12.

[0064] As the above description shows, the engagement elements 36 are arranged on the outer surface 14 in a net- or grid-like structure, wherein the pole area 42 and the bead 40 are free of engagement elements 36.

[0065] The engagement elements 36 have an approximately frustoconical shape in the "lower" six rows 38, i.e., those facing the edge 20. In the "upper" rows, i.e., those facing the pole 24, the engagement elements 36 have a more prismatic, wedge-shaped structure. The height of the engagement elements 36 decreases with decreasing distance from the pole 24. This can be understood, in particular, to mean that the engagement elements 36 project further from the base body 12 the greater their distance from the pole 24. As mentioned, the longest engagement elements are located in the uppermost row 38, which, viewed from above on the outer surface 14, have an approximately rectangular structure.

[0066] The engagement elements 36 each have a first side surface 48 facing the plane 32 and a second side surface 50 facing the bone. The side surfaces 48 and 50 each define lines of intersection with planes perpendicular to the polar axis 34. In particular, the first side surfaces 48 of the lower six rows 38 are arranged in planes, or substantially in planes, perpendicular to the polar axis 34. In the five upper rows 38, the first side surfaces are essentially formed by lateral walls of the circumferential grooves 44.

[0067] The second side surfaces 50 are angled, except for the engagement elements 36 in the top row 38. The engagement elements 36 of the lower ten rows are therefore flattened at their free ends and free of points.

[0068] Furthermore, the engagement elements 36 are wider at their base, where they are connected to the base body 12, than at their free ends. Extending from their free ends, they have flared side surfaces 52 and 54, which are inclined relative to the planes defined by the rows 46 ( Fig. 3).

[0069] The engagement elements 36 serve to achieve primary stability of the socket 10 during anchoring in the bone. Typically, the bone is prepared with contour 18 such that the engagement elements 36 project beyond contour 18 towards the bone with their free ends. This means that the socket 10 is selected to have an excess of dimensions relative to contour 18 in the area of ​​the engagement elements 36. When the socket 10 is inserted, the engagement elements 36 engage with the bone, so that the socket 10 is anchored in the bone by an interference fit due to the excess dimensions.

[0070] It proves advantageous that the engagement elements 36 are arranged on the outer circumference of the socket 10, extending close to the rim 20. The approximately rectangular engagement elements 36 of the uppermost row 38, as seen from above, serve as guide elements that facilitate the insertion of the socket 10 into the bone. It is also advantageous for facilitating the insertion of the socket 10 into the bone that the height of the engagement elements 36 decreases with decreasing distance from the pole 24.

[0071] The primary stability provided by the engagement elements 36 for anchoring the pan 10 is supplemented by secondary stability ensured by a coating 56 on the outer surface 14. The coating 56 extends substantially over the entire outer surface 14, with the exception of the bead 40 at the edge 20. The locking element 30 may also have a coating 56. If the base body 12 does not include an opening 26 at pole 24, the coating 56 preferably extends over the entire pole 24.

[0072] The coating 56 is an osteointegrative coating which, although not shown in detail in the drawing, exhibits high porosity on its side facing the bone. This high porosity creates a large surface area facing the bone. This promotes the ingrowth of bone or bone material onto the coating 56 and thus onto the acetabular cup 10. The resulting secondary stability complements the primary stability achieved by the engagement elements 36 and ensures a particularly reliable fit of the acetabular cup 10 to the bone.

[0073] The coating 56 is applied, for example, by a plasma coating process. In this process, the base body 12 with the intervention elements 36 formed on it can be placed in a reaction chamber containing a gas at low pressure. A plasma can be ignited in the gas, for example argon, under the influence of which the coating 56 is deposited onto the base body 12. The coating material, for example titanium and / or calcium phosphate, can be vaporized in the reaction chamber or introduced into the reaction chamber by means of a carrier gas.

[0074] It may also be provided that the coating 56 comprises more than one layer, for example a “lower” titanium layer facing the base body 12 and an “upper” calcium phosphate layer facing the bone.

[0075] The coating 56 has an average thickness of approximately 200 µm to approximately 500 µm, for example approximately 350 µm.

[0076] In particular, the coating 56 has different layer thicknesses. In this context, "different layer thicknesses" can be understood to mean, in particular, that the average thickness of the coating 56 varies, but its porosity is identical or essentially identical even in sections of different thicknesses.

[0077] The porosity of the coating 56 can be approximately 25% to approximately 50%, measured as the ratio of holes present in the coating 56 to a solid material.

[0078] In the Fig. 4 and Fig.Figure 5 shows in particular that the thickness of the coating 56 on the second side surface 50 is greater than on the first side surface 48, whereas the porosity is essentially the same. This applies at least to the lower eight rows 38 of engagement elements 36. In at least these rows 38, the coating 56 on the engagement elements 36 is formed such that the coating 56 forms a bead-like overhang at their free ends and projects beyond the coating 56 on the first side surfaces 48 in the direction of the plane 32. In an axial sectional view, the engagement elements 36 with the coating 56 applied to them thus have an approximately fin-shaped form.

[0079] The coating 56, which extends at the free ends towards the plane 32, forms an undercut 58 in a direction transverse to the plane 32. This undercut 58 can be formed during manufacturing due to the coating 56, thus eliminating the need for mechanically creating undercuts on the engagement elements 36 themselves, thereby simplifying the production of the cup 10. The undercut 58 ensures a particularly reliable fit of the cup 10 in the bone, utilizing the primary stability provided by the engagement elements 36 and the supporting secondary stability provided by the coating 56.

[0080] As mentioned, the invention also relates to a method for manufacturing the pan 10. In the manufacture of the pan 10, a base body, for example made of titanium, can be provided from which the base body 12 can be manufactured by turning and / or milling. For example, the base body is machined in an initial state by turning, forming the inner surface 16 and the outer surface 14, excluding the engagement elements 36. The grooves 44 can be formed by turning on the outer surface 14.

[0081] In a subsequent machining process, the engagement elements 36 can be produced, in particular by milling the base body. For example, at least one milling tool is provided that moves from the pole 24 towards the edge 20 and / or vice versa along the outer surface 14. In particular, two milling tools can be provided that move in opposite directions from the pole 24 to the edge 20 and vice versa. By milling, the engagement elements 36 can be produced in the form shown in the drawing, and therefore the base body 12 can be completed.

[0082] In a subsequent manufacturing step, the coating 56 can be applied to the outer surface 14, for example, using the plasma coating process mentioned above. With the present design of the engagement elements 36, the aforementioned thickness difference of the coating 56 on the first side surfaces 48 and the second side surfaces 50, as well as the bead-shaped overlap of the coating 56 at the free ends of the engagement elements 36 in the direction of the plane 32, results in a manufacturingly simple manner.

Claims

Artificial socket (10) for a joint implant, wherein the socket (10) comprises a cup-shaped base body (12) with a rim (20) and a pole (24), and wherein the base body (12) has engagement elements (36) projecting towards the bone on an outer surface (14) facing a bone in the insertion position, wherein the base body (12) is coated at least partially on the outer surface (14) with an osteointegrative coating (56), wherein the engagement elements (36) have a first side surface (48) facing a plane (32) defined by the rim (20), and a second side surface (50) facing the bone, characterized in that the coating (56) on the first side surface (48) is thinner than on the second side surface (50) and / or that the engagement elements (36) are coated at least partially in such a way thatthat the coating (56) extends beyond the coating (56) on the first side surface (48) at its free ends in the direction of a plane (32) defined by the edge (20) and the engagement elements (36) with the coating (56) applied to them form an undercut (58) in a direction transverse to the plane (32). Pan according to claim 1, characterized in that the base body (12) is coated with the coating (56) at least on a section of the outer surface (14) provided with engagement elements (36). Pan according to claim 1 or 2, characterized in that the base body (12) is completely or substantially completely covered with the coating (56) on the outside (14). Pan according to one of the preceding claims, characterized in that the coating (56) comprises or consists of titanium and / or calcium phosphate. Pan according to one of the preceding claims, characterized in that the coating (56) is of different thicknesses in sections. Pan according to one of the preceding claims, characterized in that the base body (12) is free of engagement elements (36) at a pole area (42) extending over the pole (24). Pan according to claim 6, characterized in that the base body is free of engagement elements (36) from the pole (24) over an angle of approximately 30° to approximately 50°, with respect to a polar axis (34) of an ellipsoid defined by the base body (12). Pan according to one of the preceding claims, characterized in that the engagement elements (36) extend to the edge (20) or substantially to the edge (20). Pan according to one of the preceding claims, characterized in that the engagement elements (36) are arranged on the base body (12) in several circumferential rows (38), each defining a plane perpendicular to a polar axis (34) defined by the base body (12). Pan according to one of the preceding claims, characterized in that the engagement elements (36) are arranged on the base body (12) in several rows (46), each defining a plane containing a polar axis (34) defined by the base body (12). Pan according to one of the preceding claims, characterized in that the engagement elements (36) are designed differently depending on their position on the base body (12). Pan according to claim 11, characterized in that the height of the engagement elements (36) relative to the base body (12) decreases with decreasing distance to the pole (24). Pan according to one of the preceding claims, characterized in that a) in relation to a direction from edge (20) to pole (24), the first side surface (48) is shorter than the second side surface (50) and / or b) the engagement elements (36) do not form an undercut (58) in the direction transverse to the plane (32). Pan according to one of the preceding claims, characterized in that the engagement elements (36) are truncated pyramidal, truncated conical or prismatic in shape. A method for manufacturing an artificial socket (10) of a joint implant, comprising the following process steps: - providing a cup-shaped base body (12) with a rim (20) and a pole (24); - forming protruding engagement elements (36) on an outer surface (14) of the base body (12) facing a bone in the insertion position, wherein the engagement elements (36) are formed with a first side surface (48) facing a plane (32) defined by the rim (20) and a second side surface (50) facing the bone; and - coating at least one of the sections of the outer surface (14) with an osteointegrative coating (56);characterized in that the engagement elements (36) on the first side surface (48) are coated with a thinner coating (56) than on the second side surface (50) and / or that the engagement elements (36) are at least partially coated such that the coating (56) at the free ends of the engagement elements (36) projects beyond the coating (56) on the first side surface (48) in the direction of a plane (32) defined by the edge (20) and the engagement elements (36) with the coating (56) applied thereto form an undercut (58) in the direction transverse to the plane (32). Method according to claim 15, characterized in that a plasma coating process is used for coating. Method according to claim 15 or 16, characterized in that titanium and / or calcium phosphate is used as the material for the coating. Method according to one of claims 15 to 17, characterized in that the base body (12) is coated at least on a section of the outer surface (14) provided with engagement elements (36). Method according to one of claims 15 to 18, characterized in that the base body (12) is completely or substantially completely coated on the outside (14). Method according to one of claims 15 to 19, characterized in that the outer surface (14) is coated with different thicknesses in sections. Method according to one of claims 15 to 20, characterized in that the engagement elements (36) are formed by turning and / or milling the base body (12). Method according to one of claims 15 to 21, characterized in that no engagement elements (36) are formed on a pole area (42) of the base body (12) extending over the pole (24). Method according to one of claims 15 to 22, characterized in that engagement elements (36) are formed on the outer circumference of the base body (12), preferably up to the edge (20) or substantially up to the edge (20). Method according to one of claims 15 to 23, characterized in that the engagement elements (36) are designed such that they are configured differently depending on their position on the base body (12), preferably that the height of the engagement elements (36) with respect to the base body (12) is designed to decrease with decreasing distance of the engagement elements (36) to the pole (24). Method according to one of claims 15 to 24, characterized in that the first side surface (48) is shorter than the second side surface (50), with respect to a direction from the edge (20) to the pole (24).

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