DE3923418A1 - Knee joint prosthesis with hinge - has small sharp projections on surfaces which abut against femur and tibia - Google Patents

Abstract

The knee-joint prosthesis consists of a femur part (1) and a tibia part (2). The tibia part (2) has a shaft (16) which is inserted in the medullary canal of the tibia. A platform is formed integrally with the shaft and the undersurface of the platform has a roughened surface (7) with small sharp projections which bite into the end surface of the tibia. The upper part of the platform has a concave surface to receive the femur part (1). The surface of this part (1) which abuts against the surface of the femur (5) is also provided with small sharp projections (7) which bite into the surface of the femur (5). USE - Knee joint prosthesis.

Description

The invention relates to an endoprosthesis in the upper part handle of claim 1 specified type and a method for the production of such an endoprosthesis.

Endoprostheses are in the form of knee joint prostheses, that replace the entire joint are, for example, from DE-PS 29 06 458 and DE-OS 33 15 401 known.  

According to DE-PS 29 06 458 are to anchor the Part of the femur ribbed, tapered in the thigh bone Cones provided in the resected accordingly Bones are cemented. The tibia part is at the foot at the upper end of the resected tibia chens equipped with a relatively long stake tet, which is also cemented. With curing However, bone cement is always a relatively high one Development of heat connected, so that damage to the Bone tissue enters. Against the use of cement speak also antibody reactions and biomechanical fac goals. It is therefore generally aimed at an anchoring to avoid bone cement.

In DE-OS 33 15 401 a knee joint endoprosthesis in which both the femoral component and the tibial component by pressing with the knee side Bone stumps are connected. Additional screws, n However, gel or other connecting means are guaranteed performance of the displacement safety still required Lich. Due to the press fit connection, the use of Bone cement not required. The disadvantage here is that Need for very tight tolerances in the manufacture of the Femoral and tibial components. Bone resection too must be done with the highest precision and therefore requires the use of template-guided special milling cutters.

The invention has for its object in an Endo prosthesis of the type mentioned in the introduction Improve bones with simple measures.  

This task is carried out with the characteristic features of the Claim 1 or by a corresponding method Claim 8 solved.

Due to the roughened surface according to the invention Chen structure, preferred by mechanical deformation of sheets or other thin-walled structures there is an intensive bone prosthesis Contact that encourages ingrowth. In particular is good rotation security guaranteed. The Festig speed of the connection can be achieved by means of bone screws the in the Be provided with the ridges of the invention rich breakthroughs are preferably provided, nor increase hen.

The ridges arise when the thin-walled is deformed locally Prosthetic material to the tear, the ridges the Be form a border in the crack area. The resulting surface procurement in a simple manner would be through appropriate processing with others Measures very difficult to achieve. When generating the Burrs using punching mandrels result in burr areas ring-shaped cross-section, which can withstand stresses in favorable holding properties in different directions have shafts. The resulting "crater" in addition advantageously from the body Fill in resorbable material that is growing additionally favored. If the craters so formed in increasing distance from the prosthesis surface too taper inside towards the opening, are formed by the ingrowing bone tissue fungal  anchors made of the body's own material, which usually good connection between bone and prostheses ensure surface.

With a corresponding design of the femoral part and / or the tibia part of a tibial prosthesis in the area the contact surface with the bone becomes a simple befe achieved with excellent turning security.

According to an advantageous development of the invention the burr-like roughening up with the prosthesis to verbin those sheets or other plate-shaped connections elements or on thin-walled areas of the prosthesis applied or applied, which in particular those for femoral or tibial longitudinal axis vertical rear surfaces of the femur or form tibia parts of a knee prosthesis. These Back surfaces act as contact surfaces between the femoral or tibia part and the corresponding knee joint stump. To achieve full-surface contact and thus good anchorage security is only one ge rings bone resection required. On the knee side Bone stumps are only flat to the longitudinal axis of the bone to grind vertical contact surfaces.

The roughening of the plate-shaped connecting elements are preferably the burrs of punch holes. In this way is a rational generation of a rough and sharp-edged surface texture of one side of the plate-shaped connecting elements ensured.

For secure fixation of the femoral part and the tibia part on the resected bone stumps is invented  "Nutmeg-like" interface form according to the invention tion essentially only one hole for the Hin performing a bone screw required, the Exit opening for the bone screw on the Femur or tibial longitudinal axis vertical back surface pre see is.

Are several at right angles to each other on the stump sectected flat surfaces are ground, this is artificial Knee joint part shaped to match. It can be useful, the knee joint part from a basic body and several plate-shaped connecting elements together to put.

Making one with a plate-shaped connector Dung element provided femoral or tibia parts according to a related invention Process mainly through simple technological implementation availability and due to the lack of special precision requirements wrestling. After creating the basic shape of the plate shaped connecting element by punching and / or sawing and / or drilling and / or milling from a metal Sheet metal is preferably removed in one operation zen of holes, the ridges of which form the roughening. The required device is with a holding grille to hold the prefabricated raw parts and a number Simultaneously operable pointed punch mandrels Mistake. with the punch mandrels between the bars of the retaining grille. The edge of the on This way punched holes is on the lattice train turned side of the plate-shaped part with a sharp  edged ridge. Then the plates shaped connecting elements preferably by welding with the back surface of the femoral or tibial component connected.

Advantageous developments of the invention are in the Un claims marked or become below together with the description of a preferred embodiment the invention using the example of a knee joint prosthesis of the figures. Show it

Fig. 1 is a schematic representation of the back surface design according to the invention on the basis of a longitudinal section through a knee joint implant,

Fig. 2 is a sectional view taken along line AA of FIG. 1,

Fig. 2a shows a second embodiment of a connecting element plattenförmi gene in the perspective of FIG. 2,

Fig. 2b shows a section through an edge zone of a plate-shaped connecting element along the line marked with A in Fig. 2a and

Fig. 3 is a perspective illustration of a punching tool for producing the burrs on a plate-shaped connecting element.

The knee joint endoprosthesis shown in FIG. 1 consists of the femoral part 1 and the tibia part 2 . Both parts are provided on their back surfaces facing the bone with plate-shaped connecting elements 3 and 4 . The Ver connecting elements 3 have the task of connecting the femoral part 1 of the artificial knee joint to the femur 5 and the connecting elements 4 have the task of connecting the tibia part 2 to the tibia 6 . The femur bone 5 is provided with a plurality of flat grindings angled to one another, as a result of which a plurality of connection elements 3 or a correspondingly curved plate-shaped connection element is also required. The connecting elements 3 and 4 are firmly connected to the femur or tibia component, preferably welded, and form the part of the wall ( 1 ) to be made available to the surgeon and the tibia part ( 2 ) of the knee joint endoprosthesis. The back surfaces perpendicular to the femur and tibial longitudinal axes are provided according to the invention in the area of contact with the bone 5 and 6 with burr-like roughening conditions 7 in the manner of a nutmeg grater. These roughening are preferably applied to designated plattenar term connecting elements 3 and 4 . This one-sided roughening 7 of the connecting elements 3 and 4 can advantageously be produced by punching holes 8 (FIGS . 2, 2a and 2a '), the resulting sharp-edged ridges forming the roughening 7 . The two parts 1 and 2 of the knee joint endoprosthesis can be pressed into the bone substance with the roughened contact surfaces, thus ensuring extensive pre-fixation. Complicated-shaped, often barbed anchoring pins, which make reoperation difficult and also have to be cemented into special bone cavities to be created for this purpose, are thus eliminated. The final fixation takes place by means of a few bone screws 9 which can be screwed through the femur or tibia part 1 or 2 including the connecting elements 3 or 4 into the femur or tibia bone 5 or 6 . The screw heads 10 are to be provided countersunk since the bone screws 9 are screwed in from the sliding surfaces 11 and 12 of the joint. The pivot point 13 of the tibia part 2 and thus the tibia 6 be found in the embodiment in the center of a ball 14 in the femoral stump 5th This ball 14 is connected via a mandrel 15 with a shaft 16 of the tibia part 2 , so that within a slot-like milling of the femur 5 and the femoral part 1 of the artificial knee joint a pivoting movement of the tibia 6 about the pivot point 13 is possible.

Fig. 2 shows a section through the plate-shaped connecting elements 4 of the tibia part 2. The bores 17 serve to pass the bone screws 9 through.

A second embodiment of a plate-shaped connec tion element 4 is shown in Fig. 2a. This second variant differs from the first variant shown in FIG. 2 primarily by the one-piece nature, the shape and the arrangement of the bores 17 for the bone screws 9 .

An edge zone of a plate-shaped connecting element 4 according to FIG. 2 or 2a with a punched hole is shown in an enlarged representation in FIG. 2b. The sheet thickness of the plate-shaped connecting element 4 is approximately 0.2 mm to 0.5 mm, while the height of the burr-like roughening 7 formed by the punch holes 8 is approximately 0.7 mm to 1.6 mm and the hole diameter is approximately 0.6 mm . The hatched inner area 8 is filled with resor bbar material, so that the ingrowth of bone substance is promoted. It can be seen that in the case of ingrowth of bone tissue in the area previously filled with resorbable material, mushroom-shaped anchors are formed from bone, which show an exceptionally good holding effect.

In Fig. 3 is a perspective view of the principle le structure of a punch for generating the surface surface structure of the plate-shaped connecting elements 3 and 4 is shown. According to a method according to the invention, after punching and / or sawing and / or drilling and / or milling the blank, punching out of holes 8 , the ridges of which are the roughening 7 bil. A suitable punching tool consists essentially of a grid-like support 19 for the blank 20 and a punch 21 which can be moved in the direction of the arrow and which has a plurality of pointed mandrels 22 , the diameter of the mandrels 22 corresponding to the hole diameter to be produced - ie preferably 0.6 mm - corresponds. The mandrels 22 penetrate the blank 20 and the gaps of the support grid 19 in the direction of the arrow when force is applied. The grid-side edges of the punch holes 8 have sharp burrs after the punching process. The plate-shaped connecting element 3 or 4 produced in this way is welded onto the femur or tibia part 1 or 2 to be connected to the femur or tibia bone 5 or 6 .

The invention is not restricted in its implementation to the preferred embodiment given above game. Rather, a number of variants are conceivable which of the solution shown also in principle make use of different types.

Claims (10)

1. Endoprosthesis, in particular knee joint prosthesis, characterized in that at least part of the surface in the region of the contact surface with the bone has bumps formed by outwardly facing ridges. 2. Endoprosthesis according to claim 1, characterized characterized in that the surveys on a sheet metal, preferably made of titanium, is provided, which in an area of the surface of the prosthesis this is connected. 3. Endoprosthesis according to claim 2, characterized in that the sheet ( 3 , 4 ) or a thin-walled area or a corresponding element of the prosthesis is provided with, in particular circular, punch holes, the upstanding edges of which have the ridges ( 7 ). 4. Endoprosthesis according to claim 3, characterized ge indicates that the punch holes are ins especially in their interior on the bone turned in the direction of increasing elevation from the Taper the denture surface.   5. Endoprosthesis according to one of the preceding claims, characterized in that at least one bore ( 17 ) is provided for the passage of a bone screw ( 9 ) in a plate-shaped area. 6. Endoprosthesis according to one of the preceding claims, characterized in that the plate-shaped connecting element ( 3 or 4 ) with an opening or a lateral recess ( 18 ), in particular for the prosthesis socket ( 16 ) or for a spike-like extension ( 15 ), is provided. 7. A knee joint prosthesis according to claim 1, characterized in that the femur ( 1 ) and / or tibia part ( 2 ) on its rear surface perpendicular to the femur and / or tibial longitudinal axis has at least one plat-shaped connecting element ( 3 , 4 ), the Surface in the area of the contact surface with the bone ( 5 , 6 ) is provided with the burr-like elevations ( 7 ). 8. A method for producing an endoprosthesis according to one of the preceding claims, characterized by the following method steps for producing and fastening the plate-shaped connecting element ( 3 or 4 ),

• - punching out and / or sawing and / or drilling and / or milling the outer contours of a plate-shaped element or sheet ( 3 or 4 ),
• - Punching out holes ( 8 ), the ridges of which form the roughening ( 7 ), using pointed punching mandrels ( 22 ).

9. The method according to claim 8, characterized by the further method step of binding, in particular welding, the plate-shaped element or sheet ( 3 or 4 ) with the surface of the prosthesis. 10. The method according to any one of claims 8 or 9, ge characterized by the further procedure step of filling up with one inside the body absorbable material.