DE2340734A1 - ARTIFICIAL JOINT REPLACEMENT - Google Patents

Description

Applicant »Feldmühle Plant and Production Company. _tr ... with limited liability

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Annex to the entry of ___9, August_1973_ 9 3 LOT 3 L

Artificial joint replacement

The invention relates to an artificial joint replacement made of at least two interacting pieces, such as shaft piece and Joint socket, in which the joint socket is firmly anchored in the pelvic bone, in particular by means of bone cement.

Prostheses as a replacement for a joint consist of at least two functionally interacting pieces, e.g. a shaft piece and a joint socket. At the end protruding from the bone, the shaft piece has a joint head and is firmly anchored in the bone by a shaft. The joint head is rotatably mounted in the joint socket. For functionality of the artificial joint replacement, an adaptation to the natural state as far as possible is an essential prerequisite.

Artificial joint replacements are known in the most varied of forms. The most common embodiment consists of a shaft piece made of a corrosion-resistant alloy based on nickel-chromium-cobalt-molybdenum and a socket joint made of polyethylene. The shaft piece and socket are made of a high-polymerized acrylic resin as a cement Bone cement firmly to the thigh or pelvic bone tied together. The abrasion of the joint socket by the metallic joint head is considerable with such prostheses. Is disadvantageous in particular, that the abrasion creates very fine foreign bodies. In addition, it is annoying that there is play in the joint due to wear results. .... 2

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In order to reduce the wear and tear of the joint socket due to wear, it has been proposed that stressed by friction To manufacture the joint socket and the joint head from sintered oxide ceramic. Due to this design, the wear has indeed increased can largely be reduced, but also this embodiment there is still a very decisive disadvantage. The oxide ceramic material is a very hard one and brittle material, which in turn forms a rigid joint socket / pelvic bone with the pelvic bone via bone cement results. This lacks the flexibility and elasticity that are given in natural bone joints is, so that the movements of the pelvic bone, for example, are not taken along and through the rigid connection Complaints to the wearer of the prosthesis. Too rigid a connection between the bone and the prosthesis part leads to load peaks and can result in bone resorption.

The invention is based on the object of creating an artificial joint replacement which suffers from the disadvantages described is free and allows the wear-resistant and firmly anchored socket to adapt to the movements of the pelvic bone.

According to the invention, this object is achieved in the case of an artificial joint replacement consisting of at least two interacting pieces, such as the shaft piece and joint socket, in which the joint socket is firmly anchored in the pelvic bone, in particular by means of bone cement is achieved in that the joint socket consists of an inner shell made of a high-melting, wear-resistant sintered metal oxide and an outer shell made of polymeric material, the inner and outer shell only being connected to one another at the edge are.

The invention is based on the knowledge that the difficulties described above are not solely due to material issues based on what can be influenced by a suitable choice of materials, but that a suitable composition

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of the joint socket in relation to the bone Role play. Up to now it has been the opinion that the pan as such is firmly and rigidly connected to the pelvic bone Must be part. All the more surprising is the present solution that the socket as such movements of the pelvic bone can participate.

It is essential to the invention that the inner shell made of sintered metal oxide and the outer shell made of polymeric material only Are positively connected at the edge. It is therefore important that the inner shell and the outer shell are not connected over a large area are, for example by gluing, so that a relative movement of the two shells to each other when force is applied by the Rod end is possible. The outer shell firmly anchored in the bone is flexible and, in contrast to the rigid ceramic bowl, can adapt to the movements of the bone.

The joint socket can be anchored in the pelvic bone in different ways. This is done first with a burr An approximately hemispherical recess is worked into the pelvic bone, which is roughly the outer curve of the joint socket is equivalent to. The socket can be inserted into this recess by means of a self-tapping socket attached to its outside Thread to be screwed in. It can also be useful if the outer shell is made of polymer material on its convex surface Side called en and has pores to allow for fastening tissue can grow into these pores. Anchoring by means of bone cement has proven particularly useful in practice. It can be of advantage if the bone cement does not cover the entire surface but only selectively the joint socket with the Pelvic bone connects. Another possibility is an elastic bone cement, the deformation of the pelvic bone can begin.

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A particularly expedient embodiment of the joint socket within the meaning of the invention is that the outer shell is attached to the inner shell by a resilient lip segment with a snap lock. This possibility is particularly simple from a construction point of view.

It can also be useful to have a screw connection between to provide the shells, with either the shells themselves having a thread on the edge, or a stud screw Mother connects both shells.

If the composition of the joint socket according to the invention is implemented to compensate for the disadvantageous effects described, a rigid connection can be created at certain points by pressing the inner shell on the outer shell. In further training the invention can therefore have a spring made of polymer between the outer and inner shell! Material or a high nonsense Layer or both can be arranged. All physiologically harmless elastomers are used for the highly elastic layer Materials such as natural rubber, synthetic cross-linkable rubbers or rubber-like cross-linkable thermoplastics in question. Silicone rubber has particularly proven itself.

All physiologically harmless and tissue-compatible polymeric materials are used as the material for the outer shell in question. Polyethylene is preferred because of its economical production method. Polyethylene can also be used as well Machinable as well as non-cutting process very well.

The inner shell represents a wear-resistant sintered molded body with high mechanical strength, in the specialist field called oxide ceramics for short. All high-melting, physiologically harmless metal oxides, such as e.g. Zirconium oxide or titanium oxide is used. Such oxide ceramic

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Shaped bodies have a high level of corrosion resistance against tissue fluids, as well as abrasion and wear resistance. Sintered aluminum oxide with a degree of purity of more than 97% is preferred as the oxide-ceramic material because of its economical production method, mechanical strength and chemical resistance at temperatures above 1700 ° C. A particular advantage is the good polishability, which results in a lower coefficient of friction of the parts sliding on each other.

The advantages achieved by the invention are primarily to be seen in the fact that the artificial joint replacement according to the invention is free of the disadvantages described above and allows the wear-resistant and firmly anchored The pan adapts to the movements of the pelvic bone. Any physiologically harmless material combinations can be used of plastic / oxide ceramic materials are used. The measures described and the advantages achieved make it possible to simply form-fit the shells of the pan, which are made of different materials, on the edge side ge connection without having to connect large areas together.

In the following, the invention is explained with reference to a drawing showing only one embodiment: Show it

1 shows an artificial joint replacement according to the invention, FIG. 2 shows a partial section of the edge-side connection between the inner and outer shell.

The artificial joint replacement shown in the figures consists of two interacting pieces, namely the Shaft piece 1 and the joint socket 10.

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The shaft piece 1 is anchored in the thigh bone 6 by a shaft 2. The upper end of the shaft 2 has a shaft neck J, onto which the joint head 4 made of sintered oxide ceramic is screwed via a thread 5. The joint socket 10 is firmly anchored in the pelvic bone 11 by means of bone cement 9. The joint socket 10 consists of an oxide ceramic inner shell 7 and an outer shell made of polymer! Material. Both shells are connected to one another in a form-fitting manner at the edge by the resilient lip segment 12. This form-fitting connection allows the relative movement, which is important according to the invention, between the rigid inner shell 7 and the flexible outer shell 8.

On its convex surface, the outer shell 8 is provided with grooves 14 in order to fasten the outer shell 8 by means of Zememt in the pelvic bone 11 to make it even more solid. the Inner shell 7 is polished on its concave surface and the joint head 4 on its convex surface.

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Claims (7)

Applicant: Feldmühle Arlagen- v.nd ProcHuctionsgesellschaft limited liability 2 3 407 34 4 Düsseldorf-Oberkassel, Fritz-Vomfelde-Platz 4 Annex to the submission of August 9, 1973 Claims 1 / Artificial joint replacement from at least two interacting Pieces, such as the shaft piece and joint socket, in which the joint socket is in particular imbued with bone cement Pelvic bone is firmly anchored, characterized in that the joint socket consists of an inner shell made of a high-melting, wear-resistant sintered metal oxide and an outer shell made of polymer material, the inner and outer shell only being connected to one another at the edges are. 2. Artificial joint replacement according to claim 1, characterized in that that the edge connection is a snap lock. 3. Artificial joint replacement according to claim 1, characterized in that that the edge connection is a screw connection. 4. Artificial joint etching according to one of claims 1 to 3, characterized in that a spring made of polymeric material is arranged between the inner and outer shell. 5. Artificial joint replacement according to one of claims 1 to 4, characterized in that between the inner and the Leave the outer shell a height before the layer is arranged. • · · · t— B09808 / 0230 ORIGINAL INSPKJTED 6. Artificial joint replacement according to one of claims 1 to 5, characterized in that the outer shell is made of polyethylene. 7. Artificial joint replacement according to one of claims 1 to 6, characterized in that the I nne ns cha IeP consists of aluminum oxide sintered at temperatures above 1700 ° C with a degree of purity of more than 97 % aluminum oxide. 509808/0230