Tibial implant

Abstract

This invention provides a tibial implant that achieves a permanent and secure fit (interlock) in the tibia through cement-free implantation. [Solution] The tibial implant (2) is manufactured from a metal alloy by additive manufacturing (particularly metal 3D printing), and the anchor portion (6) is insertable axially (10) into a channel provided in the tibia. The plateau portion (4) has an open-pore surface structure (14) on its tibial side (8) that has a first roughness and is three-dimensional porous with multiple bridges, multiple ribs, or multiple wall regions in the axial direction (10). The pin-shaped or keel-shaped anchor portion (6) has a surface structure (28) on the outer circumferential surface of the first axial anchor region (20) adjacent to the plateau portion (4) that has a second roughness smaller than a roughness of 1 without undercuts.

Description

Technical Field

[0001] The present invention relates to a tibial implant for joint replacement. The tibial implant is made of a metal alloy by an additive manufacturing method (particularly, metal 3D printing) compliant with the ASTM52900:2022-03 standard. The tibial implant includes a plateau portion and a pin-shaped or keel-shaped anchor portion. The plateau portion is provided with a support region for joining a spherical joint surface on the side opposite to the tibia, and particularly, a meniscus replacement component can be arranged thereon. The anchor portion protrudes from the tibial side of the plateau portion and extends in the axial direction, and can be inserted axially into a channel provided in the tibia.

Background Art

[0002] In this field, implants that are fixed with cement in a channel provided in the tibia and implants that are inserted without cement and finally fixed to the tibia by the growth of the bone tissue of the tibia are distinguished. Naturally, both methods aim at a permanent and reliable fit of the tibial implant in the tibia. However, in individual cases, it may be necessary to remove the implant from the tibia and replace it with a new implant.

[0003] In order to achieve a reliable fit in both cemented implants and cementless implants, many proposals have been made regarding the design of various surface areas of the implant. For example, Patent Document 1 (U.S. Patent Application Publication No. 2024 / 0041605) proposes providing a plurality of outer peripheral regions with different porosities and roughnesses on the shaft of an arthroscopic implant, and providing a lattice structure on these outer peripheral regions that can be hooked from behind (against pull-out).

[0004] Based on the problem of further developing the above-mentioned tibial implant so that a permanent and reliable fit in the tibia can be achieved by a cementless embedding and the implant can be removed as needed without damaging the tibia if necessary. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2024 / 0041605 [Overview of the project]

[0006] To solve this problem, based on the above-described type of tibial implant, the present invention proposes that the plateau portion has a three-dimensional porous open-pore surface structure (continuous pore surface structure) on the tibial side surface that contacts the bone tissue of the tibia, having a plurality of bridges, a plurality of ribs, or a plurality of wall regions that can catch in the axial direction (from behind against pull-out), and that this open-pore surface structure has a first roughness; the pin-shaped or keel-shaped anchor portion has a surface structure on the outer circumferential surface of the first axial anchor region adjacent to the plateau portion that does not have radial undercuts (parts that catch in the bone tissue against radial pull-out, i.e., parts that cannot be pulled out) (i.e., there are no bridges that can catch from behind against pull-out and no ribs that form the bridges), and that this surface structure has a second roughness smaller than the first roughness; and the pin-shaped or keel-shaped anchor portion has a second axial free-end anchor region having a smooth surface at a position axially adjacent to the first axial anchor region.

[0007] The tibial surface of the plateau portion features a surface structure with multiple axially engaging bridges, ribs, or wall regions (from behind against pull-out), allowing tibial bone tissue to grow not only on the metal surface but also within the three-dimensional porous surface structure. This firmly secures the implant body to the tibia in the direction of implantation (i.e., axially). During implant removal, a radial excision (i.e., perpendicular to the axial or implantation direction) can be made using a saw blade to sever this stable connection. Such excisions are readily possible in surgical situations.

[0008] The anchor portion has a surface structure on the outer circumferential surface of a first axial anchor region axially adjacent to the plateau portion that lacks radial undercuts (i.e., lacks bridges that can catch from behind against pull-out and ribs that form such bridges), and the second roughness of this surface structure is smaller than the first roughness of the three-dimensional porous surface structure described above, so that the tibial bone tissue formed can grow only on the surface structure of this outer circumferential surface. Since the surface structure of this outer circumferential surface lacks three-dimensional porosity and does not have bridges or ribs that can catch from behind against pull-out, internal growth of bone tissue into regions, tunnels, or pathways that can catch from behind against pull-out is impossible. The bone tissue that grows in this way has a different biological structure from bone tissue that grows in a porous structure, and the former is easier to remove under shear stress than the latter. That being said, even on a surface structure without undercuts, the growing bone tissue can form considerable adhesive force and establish a permanent connection with the surface structure. Therefore, a permanent and secure fit can be achieved that allows the joint replacement implant to withstand the stresses generated during the movement of the implant without loosening.

[0009] Furthermore, it was found to be advantageous for the second distal anchor region, connected to the first axial anchor region, to be smooth in the axial direction. This is because it facilitates the insertion of the anchor portion into the channel provided in the tibia. In addition, this smooth surface configuration prevents the bone tissue of the tibia from being scraped away when the anchor portion is inserted into the channel provided in the tibia, thereby preventing unpredictable changes in the dimensional accuracy of the channel. Moreover, it was shown that this smooth surface configuration allows for more non-traumatic removal of the implant in the second axial anchor region.

[0010] Where this specification refers to the formation of a smooth surface on or over an implant, this means that there are no three-dimensionally varying surface structures with bumps, depressions, or ribs resulting from additive manufacturing (especially 3D printing). Rather, it means that additive manufacturing is performed in a volume-filling manner, creating a closed surface that exhibits only the small surface roughness inherent in additive manufacturing (i.e., significantly less surface roughness than the second roughness of the first axial anchor region). After additive manufacturing, the smooth and uniform surface may be polished as needed.

[0011] Furthermore, in this specification, if one surface is said to have less roughness than another surface, it means that the roughness of one surface is less than that of the other surface with respect to the roughness parameter Ra, as determined according to the DIN / ISO21920-3 standard.

[0012] Furthermore, the three-dimensional porous open-pore surface structure has a depth-direction extension extending from the surrounding surface (enveloping surface), and it is advantageous if the dimension of this depth-direction extension is 1.5 mm or more (particularly 1.8 mm or more, particularly 2.0 mm or more, particularly 2.5 mm or more), and especially 4.0 mm or less (particularly 3.8 mm or less, particularly 3.5 mm or less, particularly 3.0 mm or less). Preferably, the dimension of the depth-direction extension is 2.0 mm or more and 3.5 mm or less. Within the above-mentioned region, sufficient cement-free fixation of the plateau portion of the tibial implant can be achieved by the growth of bone tissue within the three-dimensional porous open-pore surface structure.

[0013] Furthermore, it is advantageous if the open-pore surface structure of the three-dimensional porous material is formed by a continuous rib structure that forms a three-dimensional lattice, and the rib diameter of the rib structure is 0.5 mm or more (particularly 0.6 mm or more, particularly 0.7 mm or more), and especially 1.1 mm or less (particularly 1.0 mm or less, particularly 0.9 mm or less). Such features can be easily achieved by additive manufacturing technology.

[0014] Furthermore, if the diameter of a sphere that can be accommodated in the pores of the open-pore surface structure of a three-dimensional porous material is defined as the pore diameter of the open-pore surface structure, then it is advantageous for the pore diameter to be 0.8 mm or larger (particularly 0.9 mm or larger, particularly 1.0 mm or larger), and especially 1.4 mm or smaller (particularly 1.3 mm or smaller, particularly 1.2 mm or smaller).

[0015] In a further development of the present invention, it is advantageous that the surface structure of the outer circumferential surface of the first axial anchor region, which has no radial undercuts, has a depth-direction extension extending from the surrounding surface (enveloping surface), and that the dimension of this depth-direction extension is significantly smaller than the depth dimension of the three-dimensional porous open surface structure of the plateau. Based on the surface structure surrounding the surface, the dimension of the depth-direction extension of the surface structure of the outer circumferential surface of the first axial anchor region is 0.2 mm or more (particularly 0.3 mm or more) and 0.9 mm or less (particularly 0.8 mm or less, particularly 0.7 mm or less).

[0016] Furthermore, it is advantageous if the surface structure of the outer circumferential surface of the first axial anchor region, which has no radial undercuts, has multiple raised structural portions that rise from the base surface of the first axial anchor region. Here, the base surface forms a smooth outer circumferential surface region of the first axial anchor region relative to the raised structural portions, and the raised structural portions rise from the base surface as mountain-like structures.

[0017] Furthermore, it is advantageous if the surface structure of the first axial anchor region, which has no undercuts in the radial direction, has multiple raised structures that extend in a meandering manner when viewed from the radial direction.

[0018] Furthermore, it may be advantageous for the raised structure to have a plurality of flat facet surfaces (surfaces constituting a polyhedron) adjacent to each other via their edges. In particular, the raised structure may be entirely formed or bounded by such flat facet surfaces. The growth of bone tissue on flat facet surfaces is effective in addressing this problem.

[0019] Furthermore, multiple meandering raised structures can be advantageous in that they substantially demarcate the flat or smooth areas of the base surface between the multiple raised structures.

[0020] Furthermore, it is advantageous that adjacent raised structures are in contact with each other, and that areas with no or low elevation are demarcated between them. When viewed radially, the multiple raised structures form a regular and periodic pattern and a flat, mesh-like structure with openings formed by areas with no or low elevation.

[0021] However, it may also be advantageous if the meandering, adjacent raised structures are spaced apart from each other, and if there are continuous, band-like regions with no or low elevations between them.

[0022] Furthermore, it may be advantageous if the surface structure of the first axial anchor region, which has no radial undercuts, has multiple island-like raised structures spaced apart from each other. In such a case, continuous regions with no or low elevation are formed or demarcated between the multiple island-like raised structures. It is also proposed that the regions between the island-like or low elevation structures should be smooth. In this case, the island-like raised structures are mountain-like structures rising from the flat valleys between the raised structures.

[0023] Conventionally, cobalt-chromium alloys have been commonly used as materials for cementless implants, but it has been found that they have problems in terms of compatibility. In this regard, the cementless implant in the present invention can be manufactured from titanium or a titanium alloy, and both the internal growth of bone tissue into a structure (pores, tunnels, and paths) that can be hooked (from behind against pull-out) and the growth of bone tissue on a simpler surface structure without bridges or tunnels result in sufficiently reliable fitting (mating), which is advantageous.

[0024] In a further development of the present invention, the surface area of the plateau portion that does not contact the bone tissue of the tibia (i.e., the outer peripheral area that contacts soft tissue or the surface area that contacts the meniscus replacement part) may be smooth. It has been found that the implant surface that contacts soft tissue can cause problematic tissue irritation and can have a very adverse effect. In this regard, it is proposed that the smooth surface area of the plateau portion that does not contact the bone tissue of the tibia has a coating film that further reduces the surface roughness of the smooth surface area in at least some regions. Such a coating film (particularly, the surface area of the knee joint implant that contacts soft tissue) is described in German Patent Application No. 2023114759 by the applicant of the present application. Since this unpublished German Patent Application No. 2023114759 explains the formation (particularly, multilayer formation) of the coating film, the related content is incorporated herein by reference for the purpose of disclosure.

[0025] Therefore, it is particularly advantageous that the coating film has a ceramic surface (particularly, a surface made of zirconium nitride or a surface having zirconium nitride as a main component).

[0026] Also, it is advantageous that the coating film has a plurality of layers (is multilayered) and is adhered to the implant component (implant body) via an adhesion promoting layer (particularly, a layer mainly composed of cobalt-chromium or titanium).

[0027] Further, it is advantageous that the coating film includes a layer mainly composed of cobalt chromium, chromium nitride (CrN), chromium carbonitride (CrCN), and / or zirconium nitride (ZrN).

[0028] Also, it is advantageous that the coating film includes a surface layer (uppermost layer) mainly composed of zirconium nitride (ZrN) and an inner layer mainly composed of chromium nitride (CrN) or chromium carbonitride (CrCN). In the inner layer, a layer mainly composed of chromium nitride (CrN) and a layer mainly composed of chromium carbonitride (CrCN) may be alternately arranged.

[0029] Further features, details, and advantages of the present invention will become apparent from the appended claims, the drawings, and the following description of the preferred embodiments of the tibial implant according to the present invention.

Brief Description of the Drawings

[0030] The following figures are shown in the accompanying drawings.

[0031] [Figure 1] It is a perspective view of a tibial implant according to the present invention. [Figure 2] It is a three-dimensional porous surface structure on the tibial side of the plateau portion of the tibial implant in FIG. 1. [Figure 3] It is a schematic view of a surface structure without an undercut in the radial direction in the first axial anchor region of the pin-shaped or keel-shaped anchor portion of the tibial implant in FIG. 1. [Figure 4a] It is a view schematically showing the spread of the raised structure in the surface structure without an undercut in the radial direction in the first axial anchor region. [Figure 4b] It is a view schematically showing the spread of the raised structure in the surface structure without an undercut in the radial direction in the first axial anchor region. [Figure 4c] It is a view schematically showing the spread of the raised structure in the surface structure without an undercut in the radial direction in the first axial anchor region. [Figure 4d] This figure schematically shows the extent of the raised structure in the surface structure without radial undercuts in the first axial anchor region. [Modes for carrying out the invention]

[0032] Figure 1 shows a tibial implant 2 according to the present invention for use in a knee joint replacement prosthesis (artificial knee joint). The tibial implant 2 is manufactured by additive manufacturing (particularly metal 3D printing). The tibial implant 2 comprises a plateau portion 4 and a pin-shaped or keel-shaped anchor portion 6 protruding from the tibial-side surface (tibial-facing surface) 8 of the plateau portion 4. The pin-shaped or keel-shaped anchor portion 6 extends axially 10 from the tibial-side surface 8 of the plateau portion 4. The axial direction 10 also forms the implantation direction (implantation direction) of the tibial implant 2. The radial direction relative to the axial direction 10 (perpendicular to the axial direction 10) is indicated by reference numeral 12. In embodiments not shown, the plateau portion 4 facing away from the tibia may form a support area for articularizing the condyloid articular surface. In particular, a meniscus replacement component may be placed in the support area of ​​the plateau portion 4 in known (not shown) embodiments. Figure 1 is a perspective view of the tibial implant 2, viewed from diagonally below with respect to the axial direction 10 (i.e., a perspective view showing the tibial side surface 8 of the plateau portion 4).

[0033] The tibial side surface 8 of the plateau portion 4 that contacts the bone tissue of the tibia is formed of a three-dimensional porous open-pore (continuous pore) surface structure (hereinafter referred to as "open-pore surface structure 14"). The open-pore surface structure 14 has multiple bridges (bridging portions), multiple ribs (beam portions), or multiple wall regions that can be hooked from behind (against pull-out) in the axial direction 10 and other directions. Figure 2 shows an enlarged view of the three-dimensional porous open-pore surface structure 14. In Figure 2, a rib structure forming a three-dimensional lattice can be seen in the open-pore surface structure 14. The open-pore surface structure 14 (rib structure) is composed of multiple ribs 16 connected in a lattice pattern. These ribs 16 form multiple bridges (bridging portions), multiple ribs (beam portions), or multiple wall regions that can be hooked from behind (against pull-out) in multiple directions. As a result, the open-pore surface structure 14 and its ribs 16 can be hooked from behind (against pull-out) in all directions (i.e., axial 10 and radial 12) by the internally growing tibia bone tissue. This creates a close connection between the tibia bone tissue and the tibial side surface 8 of the plateau 4, achieving a secure fit (fit) of the tibial implant 2 in the tibia. The sphere 18 shown in Figure 2 is illustrated to show the size of the pore diameter in the three-dimensional porous open-pore surface structure 14. The sphere 18 is not part of the open-pore surface structure 14 and is used for illustrative purposes only. The ribs 16 of the rib structure (lattice structure) result in a first roughness Ra of the open-pore surface structure 14. The first roughness Ra has a depth extension (depth dimension) T1. As mentioned above, the depth extension (depth dimension) T1 extends from the enveloping surface (outer surface) that is applied from the outside and contacts the open-pore surface structure 14 to the three-dimensionally dense metal base surface (base surface) of the plateau portion 4. The same applies to the rib diameter d and hole diameter D (see Figure 2 for both).

[0034] A pin-shaped or keel-shaped anchor portion extends axially 10 from the tibial surface 8 of the plateau. The anchor portion 6 comprises a first axial anchor region 20 and a second axial anchor region 22 adjacent thereto. The second axial anchor region 22 forms the distal end 24 of the entire pin-shaped or keel-shaped anchor portion 6.

[0035] As shown in Figure 1, the first axial anchor region 20 has a surface structure 28 on its outer circumferential surface. The surface structure 28 has no undercuts in the radial direction 12 (parts of bone tissue that catch on to pull-out in the radial direction 12, i.e., parts that cannot be pulled out), and has no bridges or ribs that form bridges. Figure 3 schematically shows the configuration of the surface structure 28 without undercuts in the radial direction 12. Figure 3 is a view from the radial direction 12 (i.e., a view of the outer circumferential surface of the first axial anchor region 20). In the example shown in Figure 3, the surface structure 28 is formed by a plurality of raised structures 32 extending (raising) from the base surface 30 of the first axial anchor region 20. In the exemplary and preferred illustrated example, the base surface 30 is smooth and flat with respect to the raised structures 32. In the illustrated example, the raised structures 32 are formed and bounded by a plurality of flat facet surfaces 34. These facet surfaces 34 are adjacent to each other via substantially straight edges 36. The surface structure 28 has a depth extension (depth dimension) T2 (not shown). As described above, the depth extension (depth dimension) T2 extends from the enveloping surface (outer surface) that contacts the raised structure 32 from the outside to the three-dimensionally dense metal base surface (base surface) 30 of the first axial anchor region 20.

[0036] Figures 4a to 4d show examples of the arrangement of raised structures 32 in a surface structure 28 without undercuts in the radial direction 12. Figures 4a to 4d show greatly simplified examples in a two-dimensional plan view without showing the three-dimensional structure. Figures 4a to 4d show the paths and extensions of raised structures 32 in various embodiments in a plan view of the first axial anchor region 20 as seen from the radial direction 12. In Figures 4a to 4d, three-dimensional configurations such as boundaries formed by facet surfaces 34 as shown in Figure 3 are not necessarily presented or shown. Rather, the issue shown in Figures 4a to 4d concerns the arrangement and extension of raised structures 32 in the first axial anchor region 20. Figure 4a shows multiple bellows-like or zigzag-like raised structures 32 that meander in the front-rear direction. These raised structures 32 are indicated by reference numeral 38. In Figure 4a, the meandering, adjacently positioned raised structures 32 form contact points 40. As a result, a mesh-like region 42 with no or low elevations is surrounded or partitioned between adjacent raised structures 32. As described above, the mesh-like region 42 can be formed by a smooth region of the metal base surface (base surface) 30 of the first axial anchor region 20.

[0037] In the diagram shown in Figure 4b, adjacent meandering raised structures 32 and 38 have only a few contact points 40. As a result, elongated regions 42 with no or low elevations are partitioned between the raised structures 32 and 38. This can give the impression of a flat, torn net.

[0038] In Figure 4c, adjacent meandering raised structures 32 and 38 are spaced apart and do not come into contact with each other. As a result, a continuous, band-like region 46 with no or low elevation is formed between the raised structures 32 and 38.

[0039] Finally, Figure 4d shows a surface structure 28 in which multiple raised structures 50 are formed, spaced apart in an island-like manner. These raised structures 50 are particularly preferably raised from the smooth metal base surface (base surface) 30 of the first axial anchor region 20.

[0040] The second axial anchor region 22 adjacent to the first axial anchor region 20 does not have a three-dimensional porous surface structure, is smooth, and may be polished. Macroscopic recesses 52 are not intended here, but may be provided.

[0041] Finally, it should be noted that the plateau portion 4 also has a surface area 60 that does not come into contact with the bone tissue of the tibia. This surface area 60 forms the outer periphery of the plateau portion 4 and comes into contact with the soft tissue during implantation. This surface area 60 is smooth. Furthermore, as described in detail above and in the referenced prior art, an additional coating film 62 may be provided to further reduce the surface roughness of the smooth surface area 60.

Claims

1. In particular, a tibial implant for joint replacement (2) manufactured from a metal alloy by an additive manufacturing method such as metal 3D printing, The aforementioned tibial implant (2) is A plateau portion (4) on the opposite side of the tibia, provided with a support area for articularizing the condyloid articular surface, and in particular, a plateau portion (4) on which a meniscus replacement component can be placed, The system includes a pin-shaped or keel-shaped anchor portion (6) that protrudes from the tibial side surface (8) of the plateau portion (4) and extends axially (10) away from the plateau portion (4), and the anchor portion (6) is insertable axially (10) into a channel provided in the tibia, The plateau portion (4) has a three-dimensional porous open-pore surface structure (14) on the tibial side surface (8) that contacts the bone tissue of the tibia, having multiple bridges, multiple ribs, or multiple wall regions that can be gripped in the axial direction (10). The open pore surface structure (14) has a first roughness, The anchor portion (6) has a surface structure (28) on the outer circumferential surface of the first axial anchor region (20) adjacent to the plateau portion (4) that is free of undercuts in the radial direction (12) and free of a bridge that can be caught and ribs that form the bridge. The surface structure (28) has a second roughness that is less than the first roughness. The anchor portion (6) includes a second axial free end anchor region (22) having a smooth surface, located adjacent to the first axial anchor region (20) in the axial direction (10). A tibial implant characterized by the following features.

2. The open pore surface structure (14) has a depth extension (T1) that extends from the surface surrounding the open pore surface structure (14), The dimension of the depth extension (T1) is 1.5 mm or more, particularly 1.8 mm or more, particularly 2.0 mm or more, particularly 2.5 mm or more, particularly 4.0 mm or less, particularly 3.8 mm or less, particularly 3.5 mm or less, and particularly 3.0 mm or less. The tibial implant according to feature 1.

3. The open-pore surface structure (14) is formed by a continuous rib structure that forms a three-dimensional lattice. The rib diameter (d) of the open-pore surface structure (14) is 0.5 mm or more, particularly 0.6 mm or more, particularly 0.7 mm or more, particularly 1.1 mm or less, particularly 1.0 mm or less, and particularly 0.9 mm or less. A tibial implant according to claim 1 or 2.

4. When the diameter of a sphere that can be accommodated in the pores of the open-pore surface structure (14) is defined as the pore diameter (D) of the open-pore surface structure (14), The hole diameter (D) is 0.8 mm or larger, particularly 0.9 mm or larger, particularly 1.0 mm or larger, particularly 1.4 mm or smaller, particularly 1.3 mm or smaller, and particularly 1.2 mm or smaller. A tibial implant according to any one of claims 1 to 3.

5. The surface structure (28) of the first axial anchor region (20) without undercuts in the radial direction (12) has a depth extension (T2) extending from the surface surrounding the surface structure (28), The dimension of the depth extension (T2) is 0.2 mm or more, particularly 0.3 mm or more, and 0.9 mm or less, particularly 0.8 mm or less, particularly 0.7 mm or less. A tibial implant according to any one of claims 1 to 4.

6. The surface structure (28) of the first axial anchor region (20) without undercuts in the radial direction (12) has raised structural portions (32, 38, 50) that rise from the base surface (30) of the first axial anchor region (20). A tibial implant according to any one of claims 1 to 5.

7. The surface structure (28) of the first axial anchor region (20) without undercuts in the radial direction (12) has a plurality of raised structural parts (32, 38) that meander when viewed from the radial direction (12). A tibial implant according to any one of claims 1 to 6.

8. The raised structural portion (32, 38, 50) comprises a plurality of flat facet surfaces (34) adjacent to each other via an edge portion (36). The tibial implant according to claim 6 or 7.

9. The plurality of raised structures (32, 38) divide the flat or smooth region of the base surface (30) between the plurality of raised structures (32, 38). The tibial implant according to claim 7 or 8.

10. The adjacent raised structures (32, 38) are in contact with each other, and a region (42) without or with low elevation is separated between the adjacent raised structures (32, 38). A tibial implant according to any one of claims 7 to 9, characterized by the features described herein.

11. The adjacent raised structures (32, 38) are spaced apart from each other, and between the adjacent raised structures (32, 38) there is a continuous, band-like region (42) that is either flat or low in elevation. A tibial implant according to any one of claims 7 to 9, characterized by the features described herein.

12. The surface structure (28) of the first axial anchor region (20) which has no undercuts in the radial direction (12) has a plurality of island-like raised structures (50) that are spaced apart from each other. A tibial implant according to any one of claims 1 to 11.

13. Made of titanium or titanium alloy, A tibial implant according to any one of claims 1 to 12.

14. The surface area (60) of the plateau portion (4) that does not come into contact with the bone tissue of the tibia, that is, the outer peripheral area that comes into contact with the soft tissue or the surface area that comes into contact with the meniscus replacement component, is smooth. A tibial implant according to any one of claims 1 to 13.

15. The smooth surface region (60) of the plateau portion (4) that does not come into contact with the bone tissue of the tibia has a coating film (62) in at least a portion of the area that further reduces the surface roughness of the smooth surface region (60). A tibial implant according to any one of claims 1 to 14.

16. The coating film (62) is particularly made of zirconium nitride or has a ceramic surface with zirconium nitride as the main component. The tibial implant according to feature 15.

17. The coating film (62) has multiple layers and is bonded to the implant component via an adhesion-promoting layer mainly composed of cobalt-chromium or titanium. The tibial implant according to claim 15 or 16.

18. The coating film (62) includes a layer mainly composed of cobalt chromium, chromium nitride, chromium carbonitride, and / or zirconium nitride. A tibial implant according to any one of claims 15 to 17.

19. The coating film (62) comprises a surface layer mainly composed of zirconium nitride and an inner layer mainly composed of chromium nitride or chromium carbonitride. In the aforementioned inner layer, layers mainly composed of chromium nitride and layers mainly composed of chromium carbonitride are arranged alternately. A tibial implant according to any one of claims 15 to 18.

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