WO2012126448A1 - Method for producing a structured coating on ceramic implants - Google Patents

Abstract

The invention relates to a method for producing a structured coating on at least one part of the surface of a ceramic implant, in particular an implant which is to be placed in a bone. According to the invention, an abrasive treatment is initially carried out, subsequently, a thin layer of silicate glass, which is fixed by ceramic firing, is applied, and the thus produced layer is subsequently abrasively and/or subtractively treated. A silicate ceramic solder which can contain finely dispersed leucite (K[AlSi2Oj) is used. The abrasive treatment takes place by means of sand blasting, acid etching or by means of a combination thereof. The thus produced layer can then be functionalised, for example by means of a plasma-spray method, using a thin titanium layer which can also be subsequently provided with a calcium phosphate phase. The implants can also be, for example, components for artificial joint replacement or a spinal column implant.

Description

 Process for producing a

 structured coating on

 ceramic implants

The invention relates to a method for producing a structured coating on at least part of the surface of a ceramic implant, for example as an artificial joint replacement, in particular of an implant to be placed in a bone, in which the implant surface is abraded.

Artificial joint replacement today is a reliable operation with good service life when using metal-based implants. On the other hand, ceramic biomaterials as implant materials have clear advantages in terms of their biocompatibility and their abrasion behavior. However, a hitherto unsatisfactorily solved problem with ceramic-based implants intended to be anchored directly in a bone bed is, inter alia, those for the artificial knee or Hip replacement, the relaxation of cement-free implants due to a lack of bony integration of the smooth, machined ceramic surface compared for example to a rough blasted titanium surface.

For implant anchoring and the

Implant compatibility at the interface implant / adjacent tissue has the

Implant surface is very important. The success and speed of osseointegration are significantly influenced by the surface of the implant. For cementless implants, there may be reduced adhesion, proliferation and proliferation of osteoblasts due to insufficient macro- and microstructuring of the surface. The formation of a connective tissue push between the implant and the bone prevents the integration of the bone on the implant surface and thus leads to a reduced secondary stability and consequently to an early failure of the implant. On the other hand, an ideal implant surface can be used to optimize the biological reactions between the implant and the bone and thus to achieve a higher functional load on the implants. Therefore, in both cementless and cemented implants, a structured surface is essential for a permanent bond between the implant and the bone surface. For cementless implants used, such as the artificial joint replacement of hip, knee, shoulder, jump and finger joints, or even for implants for the spine, oxide ceramics are increasingly used. In this case, a roughening of the surface of these ceramic implants is desirable. However, this is technically not solved sufficiently until today, but it may in the usual Oberlächenbearbeitungsprozessen to a formation of cracks in the material and thus lead to a reduction of the breaking strength of the ceramic.

The object of the invention is to design a method for producing a structured coating of the type mentioned above such that a permanent connection is created between the surface of a ceramic implant and the surrounding tissue or the bone cement.

The invention solves this problem in that, in such a method, an abrasive treatment of the ceramic surface is first carried out, then a thin layer of silicate glass is applied, which is solidified in a ceramic fire, and that the layer thus produced is finally processed abrasive and functionalized , In this way, not only an optimal functionalization of that part of the implant surface, which is to connect after implantation with the surrounding tissue, achieved, but it is at the same time substantially facilitated by the coating with a glass matrix, the structure of the surface.

In a preferred embodiment of the method according to the invention is on the bone-side Surface of the implant or at least on portions thereof applied a thin layer of a ceramic solder and this is then subjected to a ceramic fire, whereby a glass-ceramic layer is produced. This produced by the ceramic fire glass-ceramic layer is firmly anchored by diffusion with the substrate and thus forms a solid bond with the im lantat. Subsequently, the layer can be sanded, acid etched or by a combination of both abraded or subtractive processed and roughened with it. This increases the direct contact with the contact surface to the bone or it results from a

Surface enlargement of the ceramic, which then a stable and adherent application of an osteoconductive or bioactive effect

Functional layer, for example of titanium powder by means of plasma spray technology and / or of

Calcium phosphate.

Preferably, in the method according to the invention a silicate ceramic solder is used, through which a thin glassy layer can be produced, which leads after the ceramic firing to a diffusion-anchored glass-ceramic layer on the thus coated surface of the implant and then, for example, with a commercial

Hydrofluoric acid preparation can be etched structure. In the case of the layer produced by the method according to the invention, it is particularly advantageous with regard to achieving optimum osseointegration in the case of a cementless implant that a leucite-reinforced glass ceramic is achieved, which is achieved in an advantageous manner in that the solder used is finely dispersed leucite (K [AlSi206]) is added. In a preferred embodiment of the method according to the invention, the implant to be conditioned further consists of an oxide ceramic.

By optimizing the implant surface provided in the method according to the invention, the implant anchoring at the implant / adjacent tissue interface is sustainably improved, thereby significantly increasing the speed of Osseo integration. In order to further accelerate this osseointegration, it is further provided in an advantageous embodiment of the method according to the invention, in addition to the surface topography, to additionally optimize the surface of the implant by chemical modification by means of a coating, for example by means of titanium plasma spraying (TPS) forms a stable titanium layer on the previously structured ceramic surface. Finally, in a particularly preferred embodiment of the method ₍ according to the invention), the chemical composition of the implant surface is to be further optimized by a final coating with calcium phosphate, this phase being replaced shortly after the implantation by newly forming bone tissue.

The invention will be explained in more detail with reference to an embodiment shown in the drawing. Show it:

1 shows a femoral component of an artificial knee joint as an example of a cementless insertable implant in perspective view, Fig. 2 is a schematic representation of the femur fixed on the femur

Knee end component

Figures 3 to 7 are schematic representations of a vertical section through the surface of an implant according to FIG l in different phases of the surface conditioning.

The illustration according to FIG. 1 shows a femoral knee joint implant 1 in perspective

Representation, which consists of an oxide ceramic in the case of the embodiment shown here.

For better integration of the cementless implant in the bone tissue of the femur 3 or to achieve a higher bone cement adhesion to the implant, the bone-side surface 2 of the implant is first roughened by sandbars according to the method shown in Figures 3 to 7, so that the in Fig. 4 structure shown with a surface 4 is formed. Subsequently, according to FIG. 5, a very thin layer 5 of a silicate glass is applied to the surface 4, in the case of the exemplary embodiment described here, this is done by spraying. This layer 5 is converted by a ceramic fire to a diffusion layer which diffuses into the implant 1, as indicated by the dotted line 4 'in Fig. 5. By a removing process, in the case of the embodiment of a combination of sandblasting and acid etching described here, this layer 5 is given a surface structure 6, as shown in FIG. Subsequently, the implant 1 can be inserted into the bone 3 with a suitable khoch cement, usually based on polymethyl methacrylate (PMMA). In the case of cemented implants, the structure 6 significantly improves the adhesion of the bone cement to the implant 1. In order to further increase the roughness of the surface 6 of the layer 5 and thus further increase the strength of the connection of the implant and bone or implant and bone cement, it is possible to increase this Lot additional finely dispersed leucite {K [AlSi206]) are introduced.

If a cement-free implantation is provided, then in a further step shown in FIG. 7, the generated surface structure 6 is provided with a thin layer of titanium, for example by means of a plasma spray technique. This layer 7 can finally be provided with a calcium phosphate phase. By conditioning the implant surface with a layer based on a silicate glass, the body's own hydroxyapatite (Ca5 (OH) (P04) 3) can be released, which additionally favors this process.

Also in this case, the implant 1 in the relevant bone, in the case described here in the bone 3, is used. The structured layer 7 promotes colonization with bone cells and consequently the ingrowth of the implant 1 into the surrounding bone tissue, wherein the applied calcium phosphate phase is replaced within a short time by newly forming bone tissue.

Claims

Patent claims 1. Verf hren for producing a structured coating on at least a portion of the surface of a ceramic implant, for example as artificial joint replacement, in particular an implant to be placed in a bone, in which the implant surface is abraded, characterized in that initially takes place an abrasive processing , then a thin layer (5) of a silicate glass is applied, which is solidified in a ceramic fire, and that the layer thus produced is finally abraded and functionalized. 2. The method according to claim 1, characterized in that on the surface (6) of the layer (5) a layer (7) made of titanium is applied. 3. The method according to claim 2, characterized in that the layer (7) is applied by means of a plasma spray technique. 4. The method according to claim 2, characterized in that the layer (7) by means of a chemical vapor deposition (CVD) is applied. 5. Verf Hren according to one of claims 1 to 4, characterized in that on the layer (7) a calcium phosphate layer is applied. 6. The method according to any one of claims 1 to 5, characterized in that a silicate ceramic solder is used. 7. The method according to claim 6, characterized in that the solder contains finely dispersed leucite <K [AlSi206]). 8. The method according to any one of claims 1 to 7, characterized in that the abrasive machining by means of sandblasting, acid etching or by a combination of both takes place. 9. Verf Hren according to one of claims 1 to 8, characterized in that at least partial regions of the implant are coated with a glass matrix and patterned by a removing process. 10. The method according to any one of claims 1 to 9, characterized in that the implant consists of an oxide ceramic. 11. The method according to any one of claims 1 to 10, characterized in that the structured surface for use in cementless ceramic implants has a roughness of Rz _t 20 μπι and the coating is firmly connected to the base material 12. The method according to any one of claims 1 to 10, characterized in that the structured surface for use in cemented ceramic implants has a roughness of Rz s 20 μτη and the coating is firmly connected to the base material.