DE4437479A1 - Endoprosthesis for hip or knee joint - Google Patents

Abstract

The spherical head of a hip joint prosthesis (1) is located at the end of a shaft for insertion in the patients femur. The shaft has a series of longitudinal projections (3) running a short distance down its side at the top of the prosthesis which have sharp edges to engage in the bone when inserted during the operation. The spherical head of the prosthesis engages within the inner section (2) of an acetabular cup prosthesis which is fixed into the hip of the patient. The acetabular cup prosthesis has projections arranged around its circumference which are thin and blade-shaped in structure with a sharp cutting end area (4). When the femur section and the acetabular cup section of the prosthesis are implanted, the projections cut into the bone and hold them secure. After a time, tissue grows around the projections thus further increasing the security of the implants.

Description

The invention relates to an endoprosthesis in the upper part handle of claim 1 mentioned type.

A known hip joint prosthesis of the type in question has a base body that is elongated and above its predominant length in a corresponding cavity of a long bone is inserted while its out projecting end has a cone for holding a Ball serves. The ball moves when implanted in a bearing pan one inserted into the hip bone Stock part.

To avoid relative movements of the elongated th basic body, it is known to base this body with Ze ment. This is complex and has the disadvantage that the base body only for the purpose of replacement heavy from the surrounding bone tissue, with which meanwhile an intergrowth has taken place.

It is therefore generally desirable to use the basic body to implant without cement. However, there is a fundamental principle Lich the danger that a between the prosthesis and bone connective tissue intermediate layer, which is then the result of Is relative movements.

The invention has for its object an Endopro thesis for insertion into the body to replace a joint  to create that is implantable without cement and in which the Danger of relative movements between the prosthesis and the bone is reduced.

The object underlying the invention is achieved by solved the teaching specified in the characterizing part of claim 1.

The basic idea of this teaching is based on the Basic body to provide knife-like projections that are not only in the cancellous bone, but also in the inner corticalis cut into and so a support of the main body of the Endoprosthesis on the firmer parts of the bone tissue Act. At the same time, there is the advantage that the mes protrusions like an enlargement of the total surface cause large-scale bone growth light. The knife-like can in a known manner Protrusions roughened to improve growth behavior or be coated, for example with hydroxyapatite.

Since the knife-like projections are not form-fitting Result in embedding, as is the case with one Cementing the case, such an Im Later loosen the plantat more easily for the purpose of replacement and remove.

A further development of the invention is that Basic body is essentially round and that the mes ser-like projections in a star shape away from the base body extend. This embodiment can be particularly one manufacture professionally, in particular according to a training of this Embodiment in which the main body essentially is hemispherical. This embodiment is special suitable for the formation of an acetabular cup of a hip steer.

Another development of this embodiment be is that the sharp edges are each arched, preferably run in a circular arc. This version too tion form is particularly easy to manufacture. Another Embodiment of the invention is that the reason  body is elongated so that the knife-like projections ge have the shape of ribs that are parallel to each other and in Direction of the longitudinal expansion of the base body. This body, which is part of a hip prosthesis, can then be placed in an appropriately prepared cavity of the thigh bone, with the ribs with their sharp outer edges not only depending on the remeasurement into the cancellous bone, but also into the inner corticalis to cut.

An embodiment of the invention is that the base body is arched, the outside on the Sliding surface and on its inside the knife-like fore has cracks. The basic body is therefore part of a knee joint. The knife-like projections are expedient arranged in two levels, spaced apart and par allel to each other and the arched body cut substantially vertically.

Based on the drawing, the invention is intended to be at an off example will be explained in more detail.

Fig. 1 shows a section II as shown in FIG. 2 by a joint socket of a hip joint,

Fig. 2 is an axial top view of Fig. 1,

Fig. 3 shows an embodiment of the invention for the mount shows a ball of an Hüftge Lenk's in a first view,

Fig. 4 shows the embodiment of FIG. 3 in the drawing from the left,

Fig. 5 shows a third embodiment, in conjunction with a knee joint, placed on a bone,

Fig. 6 shows the implant according to FIG. 5 in a perspective view and

FIG. 7 is a perspective view of FIG. 6 in a position rotated by 90 °.

The embodiment shown in FIGS. 1 and 2 has a hemispherical base body 1 with a kalottenför shaped bearing shell 2 . From the base body 1 are essentially star-shaped knife-like projections 3 , which are sector-shaped and have their sharp edges 4 in the direction of implantation, that is in Fig. 1 to un th

Fig. 1 is a section II through Fig. 2, in the Lich Lich the star-shaped orientation of the projections 3 is to be recognized.

Should be is in the implantation of the endoprosthesis according to FIGS. 1 and 2 Herge in the bone, in which an acetabular cup, a spherical cut-out accordingly to the outer contour of the base body 1 generates. Then the implant is pressed or hammered in, the knife-like projections 3 with their sharp edges 4 digging into the adjacent bone tissue and thus securing the base body 1 against movements, in particular also against rotational movements. Bone tissue grows on the projections 3 , which improves the mounting of the implant.

FIGS. 3 and 4 of the invention for supporting a ball 5 show, in two mutually twisted 90 ° illustrations an embodiment of a stent according to a non-illustrated long bones. As a result, the ball 5 engages in a bearing shell 2 of a base body 1 according to FIGS. 1 and 2, although the representation in FIGS. 3 and 4 is reduced compared to that according to FIGS . 1 and 2. The ball 5 sits firmly on a cone 6 at one end of a base body 7 , which is shaped so that it can be inserted into a prepared cavity of a tubular bone. On the base body 7 there are ribs 8 , which have sharp edges 9 towards the outside and taper in and out in the direction of insertion. When introducing the base body 7 in a complementary cavity created in a tube bones, the ribs 6 dig into the firmer areas of the bone, whereby the base body 7 is held firmly, in particular, also against rotational movements.

FIG. 6 shows a further exemplary embodiment of an endoprosthesis according to the invention with a base body 10 which is designed in the shape of an arc and engages around the end of a bone 11 . On the outside, the base body 10 forms a sliding surface for a knee joint, while knife-like projections 12 are provided on its inside, which penetrate into the bone 11 in a knife-like manner when the base body 10 is placed on.

FIG. 6 shows the base body 10 with its projections 12 , which are somewhat modified compared to the embodiment according to FIG. 5, in a perspective representation. It can be seen that two groups of projections 12 and 13 are easily seen, which are arranged in two planes that stood in Ab and parallel to each other and cut the bogenförmi gene body 10 substantially perpendicular.

Fig. 7 shows a perspective view of the embodiment from FIG 6 in a view from the right in Fig. 6

Claims (7)

1. Endoprosthesis for insertion into the body to replace a joint, in particular a hip or knee joint, with a base body to be attached to a bone or to be brought into a cavity in a bone, in or on the sliding surfaces for replicating the joint and before jumps Improvement of the holder on and / or in a bone are provided, characterized in that the projections ( 3 ) are knife-like and each have a preferably sharp edge ( 4 ) which points away from the base body ( 1 ) and in the direction of the on - On or bringing the base body ( 1 ) in or on a bone. 2. Endoprosthesis according to claim 1, characterized in that the base body ( 1 ) is substantially round and that the knife-like projections ( 3 ) extend in a star shape from the base body ( 1 ). 3. Endoprosthesis according to claim 2, characterized in that the base body ( 1 ) is substantially hemispherical. 4. Endoprosthesis according to claim 2, characterized in that the sharp edges ( 4 ) each have an arc shape, preferably an arc shape. 5. Endoprosthesis according to claim 1, characterized in that the base body ( 7 ) is elongated and that the messerar term projections have the shape of ribs ( 8 ) which run parallel to each other and in the direction of the longitudinal extension of the basic body pers ( 7 ). 6. Endoprosthesis according to claim 1, characterized in that the base body ( 10 ) is arcuate, on its outside the sliding surface and on its inner surface the knife-like projections ( 12 , 13 ). 7. Endoprosthesis according to claim 6, characterized in that the knife-like projections ( 12 , 13 ) are arranged in two planes, which are spaced apart and parallel to each other and cut the arcuate base body ( 10 ) substantially perpendicularly.