Joint endoprosthesis.

p0001The invention relates to an endoprosthesis of a joint consisting of zwei.miteinander unconnected components that are slidably mounted against each other in the direction of power flow between them.

p0002This prosthesis has proven particularly in the form of a knee joint prosthesis to replace a damaged joint well. The implanted knee joints allow their wearers movement possibilities that are those of natural knee largely approximated. For this purpose has to be particularly favorable the_Verschieb- sensitivity of the components to today emerged. The shifts of the components in oppositely facing directions are limited by the soft tissue apparatus surrounding the endoprosthesis, where the latter is largely fulfill its function.

p0003In the course of further technical development considerations have been made, how the endoprosthesis of the knee joint can be improved in order to find even in such cases the application can, in which the soft tissue apparatus surrounding the knee joint is largely destroyed, that it for limiting the displaceability the component is no longer suitable to today.

p0004Object of the present invention is therefore to improve the endoprosthesis of the aforementioned type so that it is part of apparatus used and fully functional even in largely destroyed soft.

p0005This object is achieved in that between the at least one component is a measure of the displaceability of the components limiting stop is formed up to today.

p0006This design has the advantage that the stop absorbs the forces and initiates in the other component, which can no longer be absorbed by the soft tissue apparatus. Nevertheless permits provided with the stop endoprosthesis substantially natural range of motion while largely protecting the existing between the components and bone connections.

p0007According to a preferred embodiment of the invention, the prosthesis is formed as a knee joint prosthesis having a femoral and a tibial component. Because of the processes occurring in a knee joint movements the displaceability of the components should be against each other limited by a stop in order to ensure a long-lasting functioning of the prosthesis whilst largely sparing the bone and the soft tissue organs just in this joint.

p0008Further details of the invention will become apparent from the following detailed description and the accompanying drawings in which a preferred embodiment of the invention is for example illustrated.

p0009In the drawings:<ul><li>FIG. 1 A side view of an endoprosthesis in a partially sectioned illustration</li><li>FIG. 2 is a front view of an endoprosthesis in a partially sectioned illustration</li><li>FIG. 3 is a bottom view with a bearing plate</li><li>Fig. 4 is a rear view of a bearing plate</li><li>Fig. 5 shows a longitudinal section through a bearing plate along the line VV in Fig. 4</li><li>Fig. 6 is a front view of a trained as a hinge bolt guide piece</li><li>Fig. 7 is a section along the line VII-VII in Fig. 6</li><li>Fig. 8 is a rear view of a composite with a support plate and guide piece</li><li>Fig. 9 shows a section along the line IX-IX in Fig. 8.</li></ul>

p0010The endoprosthesis of a joint is explained using the example of a knee joint endoprosthesis. The endoprosthesis of a knee joint consists essentially of two components 1, 2, one of which is designed as a femoral component 1 and the tibial component other than the second In the femoral component 1 joins a stem 3 which is inserted into a femur of a patient, a femoral bearing half 4 at. This bearing half 4 is supported on a tibial bearing half 5, which is mounted on a stem 6 at a lower leg bone of the patient. Between the components 1, 2, a bending movements about their transverse axes against each other zulassendes first bearing 7, and a rotational movement about the longitudinal axes of the components 1, 2 against each other zulassendes second bearing 8 is arranged. The first bearing 7 consists of a pivot bearing. It is designed as a component attached to the one one hinge having a hinge pin designed as a guide piece 9 lo, which is mounted in rotation and slidingly movable on the other component the second Between the components 1, 2, a stop 11 is provided. This is designed as a guide piece lo radially at least partially surrounding collar 12 which engages behind a provided on the other component 2 stop bar. 13 The collar 12 is provided on the femoral component 1 and the stop bar 13 on the tibial component the second The first bearing 7 forming hinge is fixed in the femoral component. 1 In the guide piece lo protrudes into a its rotational movements and sliding movements the registering pin 14 which is fixedly connected to the tibial component. 2 The collar 12 is at one of the tibial component 2 facing the end 15 of the guide piece lo angeord net. The collar 12 projects beyond the guide piece lo at least partially in directions that are facing away from the pin 14th It is in the form of an annular flange, which at its the tibial component 2 opposite side 16 a supporting surface 17 on which the stop bar 13 is supported on reaching a preselected limit position in which the components 1, 2 are pushed furthest apart. The collar 12 is flattened in a rear portion of the guide piece lo, in which the two components 1, 2 approaching when performing the bending movements most. The stop strip 13 is provided on the tibial bearing half 5, which limits the tibial component 2 in the direction of the femoral component of the first The tibial bearing half 5 comprises a substantially horseshoe-shaped bearing plate 18, which surrounds the pin 14 partially. It extends substantially transverse to the longitudinal direction of the tibial component 2. At its the femoral component 1 facing top 19 it is provided with a sliding surface 2o, on which the femoral bearing half 4, 5 supported. The bearing plate 18 is provided with a substantially U-shaped recess 21, which penetrates in the longitudinal direction of the tibial component 2 substantially. The recess 21 has a front rounded portion 22 facing a front portion of the collar 12, which engages behind the abutment bar. 13 The recess 21 is adapted to one facing it, part 24 of the collar 12 in its rounded portion 22nd The stop bar 13 projects into the rounded portion 22 of the recess 21 into the rounded portion 22 and limited in the direction of the femoral component 1. The stop strip 13 is bent and extends the rounded portion 22 substantially concentrically. She maintains a distance from a top surface 25 of the bearing plate 18 carrying support 26 of the tibial component. 2 Between the stop bar 13 and the top side 25, a free space 27 is provided, which has the height of the distance between the stop bar 13 and the top of the 25th The collar 12 is mounted slidably and rotatably in the free space 27 and has opposite the recess 21 a game on. The bearing plate 18 is fixed to the support 26th This is surrounded on its upper side 25 of a rim 28 to which the bearing plate 18 is matched with her the support 26 facing bottom 29th The bearing plate 18 is the top 25 adapted form-fitting. It is mounted in its front portion 3o with a screw 31 to the bearing 26, which is at least partially submerged in the bearing plate 18th The bearing plate 18 is facing away in her the front portion 3o rear portions 32 each provided with a blind hole 33, 34, which run parallel to one another and in a plane spanned by the bearing plate 18 level. In the blind holes 33, 34 safety pins protrude, the 28 project beyond the rim towards the blind holes 33, 34th

p0011The endoprosthesis of a knee joint can be used as follows:<ul><li>The femoral component is pre-mounted in such a way that the guide piece lo forming the flexor movements permitting first camp. 7 After the two components 1, 2 are respectively connected to them facing the thigh or lower leg bone, the pin 14 is inserted into the guide piece lo, so that the pin 14 with the guide piece lo the rotational movements and sliding movements of the components 1, 2 against one another permitting second bearing 8 forms. Between the components 1, 2, the bearing plate 18 is inserted in such a way that the blind holes 33, 34 accommodate the provided on the rim 28 locking pins and the collar 12 projects into the clearance 27th Thereafter, the bearing plate 18 is lowered onto the support 26, so that it has a positive connection with the support 26 and the beaded edge 28th The bearing plate 18 is screwed with the screw 31 on the pedestal 26th</li></ul>

p0012Now, the endoprosthesis of a knee joint is fully assembled. A accompanied by such a prosthetic leg can be substantially moved like a provided with a natural knee leg. This is made possible that the components 1, 2 against each pivoted, rotated and can be moved. Although the soft tissue apparatus surrounding the knee joint endoprosthesis is no longer able to limit a drifting apart of the components 1, 2, or prevent, the endoprosthesis can be used because the formed between the collar 12 and the stop bar 13 stop 11 a drifting apart of the components 1, 2 prevented over a preselected extent.