WO2001005336A1

WO2001005336A1 - Implant designed to fill up cartilage and bone defects in joints

Info

Publication number: WO2001005336A1
Application number: PCT/EP2000/005556
Authority: WO
Inventors: Hans Grundei; Wolfram Thomas
Original assignee: Eska Implants Gmbh & Co.
Priority date: 1999-07-16
Filing date: 2000-06-16
Publication date: 2001-01-25

Abstract

The invention concerns an implant (1) designed to make up for cartilage and bone defects (10) in joints. Said implant has a body frame (2) comprising at least an anchoring plug (3) to be driven into the bone and a front plate (4) coupled to said plug. The front plate (4) is incorporated in a sliding head (5) made of a biocompatible and abrasion-resistant material. The surface of the sliding head (5) opposite the anchoring plug (3) is designed as a sliding surface (6). In another embodiment, the implant has a base element comprising at least an anchoring plug to be driven into the bone and also a sliding head produced in a biocompatible and abrasion-resistant material.

Description

Implant for filling cartilage and bone defects in joints

Description:

The present invention is concerned with an implant for filling cartilage and bone defects in joints, such as in the knee joint.

Cartilage and bone damage in joints can generally be countered by implanting a total replacement implant. Due to the massive nature of such an intervention, efforts are made to leave as much natural material in the joint as possible. Of course, this does not apply to all indications. In the case of a tumor, for example, it is often not possible to avoid implanting a total endoprosthesis. However, there are often defects that are more amenable to gentler treatment. For example, arthroscopic surgery can be used to treat cartilage and bone defects on an outpatient basis by transplanting the patient's cartilage from a less stressed joint area into the cartilage defect area. Such cartilage defects are the result of, for example, osteoarthritis, which is accompanied by excessive and premature abrasion of the cartilage, as a result of which the coating that covers the bone ends becomes ever thinner and ultimately results in bone defects. Another surgical technique that deals with this topic is, for example, cartilage cell transplantation, in which, after genetic engineering of the body's own cartilage cells, attempts are made to rebuild the cartilage by injecting these cultured cells in the area of the cartilage and bone defects. Aim of all of these efforts is to restore the natural function of the joint using the body's own material or the material obtained from it.

However, it is considered disadvantageous that in the described method of cartilage transplantation, cartilage material is removed from a healthy joint area in order to be inserted into the area of the cartilage and bone defects and to heal there. When the cartilage material is removed from the healthy area, a weakening of the cartilage material, which is in itself healthy, is consciously accepted in order to remedy the cartilage defect.

Against this background, the object of the present invention is to remedy this, ie to provide an implant for filling cartilage and bone defects, in which no additional weakening of the patient's healthy cartilage material is carried out. The implant should be accessible to arthroscopic surgery.

This object is achieved by the implant with the features of claim 1 or alternatively of claim 8. Advantageous further developments are specified in the respective subclaims.

Accordingly, according to the first alternative, the implant according to the invention has a reinforcing body with at least one anchoring pin to be driven into the bone and a head plate connected to it. This is embedded in a sliding head made of a biocompatible, abrasion-resistant material, the surface of which faces away from the anchoring pin is designed as a sliding surface.

The implant according to the invention thus takes the place of cartilage material that was previously removed from a healthy area in previous arthroscopic surgery and for filling up the cartilage and Bone defect served. The implant has a nail-like structure. The implant, with its anchoring pin, which particularly preferably has a conically tapering end, is hammered into the bone at the bottom of the cartilage and bone defect by means of several strikes by means of a percussion instrument on the head or sliding head. The top plate of the optionally metallic reinforcement body sits on the at least one anchoring pin. This is embedded or cast into a biocompatible, abrasion-resistant material, which forms the sliding partner for the natural sliding surfaces of the other joint part. After the implant has been hammered into the defect, cartilaginous connective tissue is granulated into any space between the sliding head and the natural cartilage. This also applies when using several implants according to the invention to fill a larger cartilage and bone defect. The gaps between several implants granulate with cartilaginous connective tissue after a certain time. The surface or sliding surface of the cartilage and bone defect filled with one or more implants then performs the function of natural cartilage.

When filling a defect with several implants, the distances between the anchoring pins must be determined so that the sliding heads in the peripheral area touch, but do not overlap, since they would otherwise form a stepped surface that could not function as a sliding surface. This is achieved by using placement devices that have the same dimensions as the implants that are then used in the procedure. The surgeon first places a placer with his pin, which represents the anchoring pin of the implant, on the bottom of the cartilage and bone defect to be filled and marks the point at which the anchoring pin is later driven into the bone by gently hitting the head plate. Then a second placer is placed so that its head plate that of the first placer just touches and the point at which the anchoring pin of the second implant is to be driven is also marked by a light blow on the head plate. The surgeon carries out these steps until he has filled the cartilage and bone defect practically completely with the placers by using a sufficient number and possibly using different sizes of the implant. He then removes the placers and then drives the corresponding implants with their anchoring pins into the respective marked locations in the bones.

A particularly strong hold of the sliding head on the reinforcement body can be achieved if the head plate is provided with openings through which material of the sliding head extends. A particularly intimate connection between the head plate and sliding head is achieved when the sliding head is cast with the head plate.

The biocompatible material of the sliding head can be polyurethane, for example. The selection of the biocompatible material of the sliding head as bioceramic is particularly preferred. This can advantageously be a glass ceramic, an aluminum oxide ceramic or a zirconium oxide ceramic. A composite material can also be used with advantage, as is described, for example, in EP-B-0502082 in connection with a composite pan.

Alternatively, it is proposed that the implant according to the invention have a base body with at least one anchoring pin to be driven into the bone and a sliding head connected to it. At least the sliding head consists of a biocompatible, abrasion-resistant material whose surface facing away from the anchoring pin is designed as a sliding surface. In the present case, there is no longer any reinforcement body compared to the first proposal. This simplifies the manufacture of the Implants and therefore lowers costs. Thus, according to an advantageous development of the second proposed solution, the base body and the sliding head can consist of the same material. It is particularly preferred in this embodiment that the base body and sliding head are formed in one piece.

The material for the biocompatible material is again polyurethane, bioceramics (glass ceramics, aluminum oxide ceramics, zirconium oxide ceramics) and the composite material mentioned above.

A completely metallic implant made of titanium, for example, is also conceivable.

In both alternative solutions, it is particularly preferred if the height of the sliding head is in the range between 2 and 6 mm. If several implants are used, depending on the shape of the cartilage and bone defect, implants with different heights can be used. The aim is to produce a surface that is as smooth as possible and clings to the sliding surface of the cartilage and cartilage defect that follows. In addition, the height of the sliding head can lead to a stability of the hinges.

It is preferably provided that the sliding head is circular with a diameter range of 6 to 16 mm. To fill up a cartilage and bone defect, implants with different diameters can be used in order to fill the existing defect as optimally and completely as possible.

The invention is explained in more detail below using two exemplary embodiments. Here shows: FIG. 1 shows the schematic view of the implant according to the invention in accordance with the first proposal,

Figure 2 shows the view of the top plate of the reinforcement body

1 from below,

Figure 3 shows the schematic view of the implant according to the second proposed solution

Figure 4 schematically the filling of a cartilage and

Bone defect in a condyle of the knee, and

Figure 5 is a schematic side view of the condyle of a knee joint with filled cartilage and bone defect.

The same parts are designated with the same reference symbols in the following.

The implant 1 is shown schematically in FIG. It has a reinforcing body 2, which in the present case is equipped with only one anchoring pin 3. The head plate 4 is attached to the anchoring pin 3. The reinforcing body 2 is preferably made of metal, for example titanium.

The head plate 4 is embedded in a sliding head 5, the material of which has the said properties with regard to biocompatibility and abrasion resistance. The surface of the sliding head 5 facing away from the anchoring pin 3 is designed as a sliding surface 6, as indicated by the rounding in FIG. 1 in the present case. The sliding surface 6 works together with the natural cartilage of the other joint part. The sliding head 5 has a height H and a diameter D. With different diameters D and different structural heights H, different implants can be represented which are suitable for forming a sliding surface which is essentially continuous towards the outside, following the natural cartilage which is still present, as will be explained below with reference to FIG. 5.

Figure 2 shows the view of the armoring body 2 of the implant according to Figure 1 from below. The anchoring pin 3 is attached to the head plate 4 and is surrounded by openings 7. The openings 7 ensure an intimate bond between the reinforcing body 2 and the material of the sliding head 5. For this purpose, the sliding head 5 can have appropriately designed lugs (not shown) which can lock in the openings 7, so produce a form closure. However, it is preferred to cast the mass of the sliding head 5 through the openings 7.

Figure 3 shows schematically the side view of the implant 1 '. In contrast to the proposal according to FIG. 1, the sliding head 5 'is formed in one piece with the anchoring pin 3' of the base body 2 '. Here too, the surface of the sliding head 5 'facing away from the anchoring pin 3' is designed as a sliding surface 6 '. The implant 1 'can consist of ceramic or metal. With regard to the structural height H and the diameter D of the sliding head 5 ', the same applies as explained above for the first embodiment.

FIG. 4 now shows schematically how a cartilage and bone defect 10 can be filled in a condyle 9 on the femur 8. A whole number of implants 1 of different sizes, ie with different diameters of the sliding heads and possibly different structural heights H of the sliding heads, allow the creation of an individual overall implant for the greatest possible filling of the cartilage and Bone defect 10. Remaining gaps 12 between the individual implants 1 are granulated over time by cartilaginous connective tissue.

FIG. 5 schematically indicates how a cartilage and bone defect 10 is filled in the natural cartilage layer 11 on the condyles of a knee joint. Several individual implants 1 are arranged and hammered into the bone in such a way that the smoothest possible sliding surface adjoins the natural cartilage layer 11.

With the implant it is possible to treat the relatively easy to fix cartilage and bone defects in a targeted manner without the need for serious interventions. Rather, the implant can be implanted using arthroscopic surgery. The patient is spared the need to undergo total resection of the joint when simple cartilage defects occur. Over a period of several years, an overall implant produced with the implant according to the invention can ensure that the patient can move his joint without symptoms for several years.

Furthermore, it is noted that the different structural heights of the implants, as they are arranged, for example, according to FIG. 4, also serve to lead to stability of the side bands after the defect has been filled. The side band in question slackens in the area of a defect. After the cartilage and bone defect has been filled with the implant, it regains its natural tension, which is conducive to the overall stability of the joint.

Claims

Claims:

1. Implant (1) for filling cartilage and bone defects (10) in joints, comprising an armoring body (2) with at least one anchoring pin (3) to be driven into the bone and an associated head plate (4), which is embedded in one Sliding head (5) made of a biocompatible, abrasion-resistant material, the surface of which facing away from the anchoring pin (3) is designed as a sliding surface (6).

2. Implant according to claim 1, wherein the head plate (4) is provided with openings (7).

3. Implant according to claim 1 or 2, wherein the biocompatible material of the sliding head (5) is polyurethane.

4. Implant according to claim 1 or 2, wherein the biocompatible material of the sliding head (5) is a bioceramic.

5. The implant of claim 4, wherein the bioceramic is a glass ceramic.

6. The implant of claim 4, wherein the bioceramic is an alumina ceramic.

7. The implant according to claim 4, wherein the bioceramic is a zirconium oxide ceramic.

8. Implant (1 ') for filling cartilage and bone defects (10) in joints, comprising a base body (2') with at least one to be driven into the bone Anchoring pin (3 ') and an associated sliding head (5') made of a biocompatible, abrasion-resistant material, the surface of which facing away from the anchoring pin (3 ') is designed as a sliding surface (6').

9. The implant of claim 8, wherein the base body (2 ') and the sliding head (5') consist of the same material.

10. The implant of claim 9, wherein the base body (2 ') and sliding head (5') are integrally formed.

11. Implant according to one of claims 8 to 10, wherein the biocompatible material is polyurethane.

12. Implant according to one of claims 8 to 10, wherein the biocompatible material is a bioceramic.

13. The implant of claim 12, wherein the bioceramic is a glass ceramic.

14. The implant of claim 12, wherein the bioceramic is an alumina ceramic.

15. The implant of claim 12, wherein the bioceramic is a zirconium oxide ceramic.

16. The implant of claim 10, wherein the base body (2 ') and the sliding head (5') consists of body-compatible metal.

17. Implant according to one of claims 1 to 15, in which the structural height (H) of the sliding head (5) is in the range between 2 and 6 mm.

8. Implant according to one of claims 1 or 16, wherein the sliding head (5) is circular with a diameter (D) in the range of 6-16 mm.