IMPLANT AND METHOD FOR COATING AN IMPLANT MAIN BODY

Abstract

An implant (1), in particular an acetabular implant, for implantation into a bone has, at least in parts, a surface structure (2) of raised portions (3) and depressions (4). The depressions (4) have zones coated with a porous coating (5). The raised portions are either not coated at all or are coated such that the coating has a thin layer thickness or a higher abrasion resistance in these portions. In this way, an improved abrasion behavior is reached when the implant is inserted into the bone.

Claims

1. An implant (1), in particular a hip-joint socket implant, for implantation into a bone, wherein the implant (1) has, at least in parts, a surface structure (2) comprising elevations (3) and depressions (4), the depressions (4) have zones (6) with a porous coating (5), wherein a) the elevations (3) have uncoated zones (7) which adjoin the coated zones (6) in the depressions, b) or the elevations (3) have coated zones (7) which adjoin the coated zones (6) in the depressions, wherein a layer thickness of the porous coating (5) is smaller on the elevations than in the depressions (4), c) or the elevations have coated zones which adjoin the coated zones in the depressions, wherein the coating is less porous on the elevations than in the depressions, d) or the elevations (3) have coated zones (7) which adjoin the coated zones (6) in the depressions, wherein the abrasion resistance of the porous coating (5) is greater on the elevations than in the depressions (4), and the porous coating (5) extends in a manner following a contour of the depressions (4).

2. The implant (1) as claimed in claim 1, wherein the layer thickness (d) of the porous coating (5), in the depressions (4), amounts to between 15% and 50% of a profile depth (t).

3. The implant (1) as claimed in claim 1, wherein the layer thickness (d) of the porous coating (5) in the depressions (4) is between 0.2 mm and 0.5 mm.

4. The implant (1) as claimed in claim 1, wherein the implant (1) comprises a main body (8) selected from the group consisting of titanium, zirconium, niobium, tantalum, or alloys thereof, cobalt-chromium alloy, medical steel, ceramic or polyethylene.

5. The implant (1) as claimed in claim 1, wherein the implant (1) has a porous coating (5) selected from the group consisting of titanium, zirconium, niobium, tantalum, or alloys thereof, cobalt-chromium alloy.

6. The implant (1) as claimed in claim 1, wherein the porous coating (5) is a particle coating and has particles (9) which are one of spherical, cubic or cylindrical in shape.

7. The implant (1) as claimed in claim 6, wherein the porous coating (5) has particles (9) with an average size of 200 m to 500 m.

8. The implant (1) as claimed in claim 1, wherein a porosity of the coating is set in such a manner that it is greater at the base of the depressions (4) than in a region of side flanks of the elevations (3) or on the elevations.

9. A method for coating an implant main body (8), in particular for producing an implant (1) as claimed in claim 1, the method comprising the steps of: providing the uncoated main body (8), wherein the main body (8) has, at least in parts, a surface structure (2) comprising elevations (3) and depressions (4), selectively applying a porous coating (5), in such a manner that coated zones (6) in a region of the depressions (4) adjoin uncoated zones (7) in the region of the elevations (3), and in such a manner that the porous coating (5) extends in a manner following the contour of the depressions (4).

10. The method as claimed in claim 9, wherein the porous coating (5) is selectively applied by applying a layer in the region of the elevations (3) which prevents adhesion of the porous coating (5) to a greatest possible extent.

11. A method for coating an implant main body (8), in particular for producing an implant (1) as claimed in claim 1, the method comprising the steps of: providing the uncoated main body (8), wherein the main body (8) has, at least in parts, a surface structure (2) comprising elevations (3) and depressions (4), applying a porous coating (5) in a region with the surface structure (2), removing the porous coating (5) in the region of the elevations (3), in such a manner that: a) the elevations (3) have coated zones (7) which adjoin the coated zones (6) in the depressions, wherein the layer thickness of the porous coating (5) is smaller on the elevations than in the depressions (4), b) or in such a manner that the elevations (3) have coated zones (7) which adjoin the coated zones (6) in the depressions, and in such a manner that the abrasion resistance of the porous coating (5) is greater on the elevations than in the depressions (4), c) or in such a manner that the elevations have coated zones which adjoin the coated zones in the depressions, wherein the coating is less porous on the elevations than in the depressions, and in such a manner that the porous coating (5) extends in a manner following the contour of the depressions (4).

12. The method as claimed in claim 11, wherein the porous coating (5) is removed in the region of the elevations (3) by shot blasting, shearing, brushing, turning, milling, grinding, barrel finishing, chemical or electrochemical removal.

13. The method as claimed in claim 9, wherein the porous coating (5) is applied by plasma coating, in particular by an atmospheric plasma spraying method (APS) or a vacuum plasma spraying method (VPS), by precipitation, or additive manufacturing.

14. The method as claimed in claim 9, wherein the method additionally comprises the step of sintering the main body (8) coated with the porous coating (5).

Description

[0045] Further advantages and individual features of the invention become apparent from the following description of two exemplary embodiments and from the drawings.

[0046] Schematically:

[0047] FIG. 1: shows a cross-sectional profile of the surface structure of an implant according to the invention;

[0048] FIG. 2: shows a cross-sectional profile of the surface structure of an alternative exemplary embodiment of an implant according to the invention;

[0049] FIG. 3: shows an uncoated implant main body for an implant according to the invention;

[0050] FIG. 4: shows an implant according to the invention having a surface structure with a cross-sectional profile as shown in FIG. 1;

[0051] FIG. 5: shows a sectional image of the surface structure of an implant according to the invention;

[0052] FIG. 6: shows an enlarged sectional image of the surface structure of an implant according to the invention.

[0053] As is apparent from FIG. 1, the surface structure 2 of an implant 1 according to the invention comprises elevations 3 and depressions 4. In the present case, the zones 6 coated with a porous coating 5 extend only over the depressions 4, whereas the elevations 3 have uncoated zones 7a. The surface structure 2 has a profile depth t and the porous coating 5 in the coated zones 6 has a layer thickness d.

[0054] As can be gathered from FIG. 2, the exemplary embodiment illustrated therein differs from that shown in FIG. 1 to the effect that both the elevations 3 and also the depressions 4 are coated with a porous coating 5. However, the elevations 3 have coated zones 7b, in which the layer thickness of the porous coating 5 is lower than in the depressions 4. Here, however, the coating can also simply have a lower porosity or a greater compactness than in the depression 4. Therefore, the abrasion resistance of the porous coating 5 is greater in the zones 7b than in the depressions 4. The porous coating 5 illustrated is a particle coating composed of the particles 9.

[0055] The implant main body 8 as shown in FIG. 3 was produced by making groove-shaped depressions 4 on a metal blank. This is an implant main body 8 in the shape of a spherical cap shell and having a pole 10 and an equator 11. In addition to the depressions 4 which have already been discussed, the surface structure 2 has elevations 3.

[0056] The implant 1 according to the invention which is depicted in FIG. 4 was produced from a main body 8 of the type depicted in FIG. 3, in which case a method as per claim 11 was used. Accordingly, after the provision of an uncoated main body 8, a porous coating 5 was applied in the region with a surface structure, which extends in this case from the pole 10 as far as the equator 11. Thereupon, the porous coating 5 in the region of the elevations 3 was removed again in such a manner that the layer thickness of the porous coating 5 is lower on the elevations 3 than in the depressions 4. The removal of material removes particles of relatively low adhesion, and this leads to a reduction in the layer thickness. As a result, the abrasion resistance of the porous coating 5 is greater on the elevations 3 than in the depressions 4.

[0057] FIGS. 5 and 6 show sectional images of the surface structure of implants according to the invention.

[0058] As shown in FIG. 5, the elevation 3 has an asymmetrical form in cross section. The coating 5 consisting of titanium particles is distributed differently on the steeply dropping left flank and on the somewhat flatter right flank. The dark regions of the coating correspond to pores between the light titanium particles. It is clearly visible that the layer thickness is greater in the depressions 4 than on the peak of the elevation 3.

[0059] FIG. 6 shows, yet further enlarged compared to FIG. 5, an open-pore structure of the coating 5. The light regions of the titanium particles form a rugged structure allowing for the growth of bone substance.