DE102005015598B4 - Knee joint endoprosthesis and prosthesis set with such a knee joint endoprosthesis - Google Patents

Abstract

Knee joint endoprosthesis with a femoral component (1); a tibial component (2) pivotally connectable to the femoral component (1); an inlay (31) disposed in use between the femoral component (1) and the tibial component (2) and forming at least one sliding surface (8, 10) for the femoral component (1); and a coupling member (14) rotatably connected to the femoral component (1) and having a coupling pin (16) which, in use, extends at least partially through an opening (32) in the inlay (31) extending into the tibial component (2) , characterized in that the coupling pin (16) is extendable.

Description

The invention relates to a knee joint endoprosthesis and a prosthesis set with such a knee joint endoprosthesis.

From the EP 0 791 344 A2 For example, a knee joint endoprosthesis is known which has a femoral component and a tibial component, wherein the femoral component and the tibial component are pivotably connectable. The prosthesis further includes an inlay disposed between the femoral component and the tibial component in use and forming at least one femoral component sliding surface. Furthermore, a coupling part is provided, which is rotatably connected to the femoral part and has a coupling pin, which extends in use through an opening in the inlay extending into the tibial component at least partially.

Such knee joint endoprostheses are also referred to as axial guided rotational knee endoprostheses. These prostheses, when assembled, couple to the coupling pin, which is either attached to the tibia and projects upwardly and articulates with a ring attached to the joint, or which is attached to the joint and inserted into the recess of the tibial component. The coupling pin allows on the one hand in addition to the flexion / extension movement about the pivot axis, a rotation about the tibial axis. On the other hand, it transfers the anterior / posterior pushing forces from the femur to the tibia. Finally, the coupling pin allows the distraction of the knee joint under tensile stress, so that it is not transmitted to the anchoring of the endoprosthesis.

Another example of such a knee prosthesis is from the EP 1 226 800 A2 known. In this prosthesis of the coupling pin is inserted into a condyle of the coupling part and screwed with this.

These known prostheses have the disadvantage that their geometry is fixed. It is therefore not possible to adapt these prostheses to the different physiognomy of patients accordingly. The known prostheses are problematic, in particular with regard to the risk of dislocation, since cruciate ligaments with a less pronounced tension can lead to excessive dislocation of the individual prosthesis components.

The invention is therefore based on the object, a knee joint endoprosthesis of the type mentioned in such a way that an adaptation of the prosthesis to patients with different physiognomy is possible. Furthermore, a prosthesis set is to be specified with such a knee joint endoprosthesis.

With regard to the knee joint endoprosthesis this object is achieved according to the invention by the subject matter of claim 1 and alternatively by the subject of the independent claim 11. With regard to the prosthesis set, the object is achieved according to the invention by the subject matter of claim 10.

The essence of the invention is that the coupling pin of the coupling part is extendable.

The extensible coupling pin allows inlays of varying thickness to be used so that intra-operatively, the distance between the femoral component and the tibial component can be individually adjusted, thereby generally allowing adaptation of the prosthesis to a patient's physiognomy. In particular, this means that the surgeon can decide during surgery whether to use a slightly higher or thicker inlay if the ligament tension of the cruciate ligaments is too weak to reduce the risk of dislocation. The doctor decides so during the operation, if he chooses the coupling pin a little shorter or a little longer. The ability to extend the hitch pin not only provides advantages in terms of improving ligament tension, but can generally be used to tailor the prosthesis to the particular physical conditions of a patient. In addition, the extension provides improved support in the inlay and tibial component, minimizing damage due to deformation and subsequent dislocation of the inlay.

According to the independent claim 11, the coupling part is modular, such that separate, each different lengths and / or individually extendable coupling pins are provided. With such a knee joint endoprosthesis according to the invention, the advantages described above are likewise achieved.

The prosthesis set according to the invention has the advantage that a plurality of extension pieces of different lengths are made available to the surgeon, who can adjust the distance between the remote judgment and the tibia part and thus the ligament tension by a suitable choice of a suitable extension piece.

Overall, the invention provides the advantage that the knee joint endoprosthesis can be better adapted to the respective physiognomy of a patient and dislocation of the inlay can be largely avoided.

Advantageous developments of the invention are specified in the subclaims.

Preferably, an extension piece is provided, which is connectable to the tibiaseitigen end of the coupling pin. As a result, an extension of the coupling pin is achieved in a particularly simple manner.

The extension piece may, in a preferred embodiment, comprise an extension pin having two sections of different outside diameters. In this case, the portion with the smaller diameter can be inserted into a bore in the tibial end of the coupling pin. The larger diameter of the other portion of the extension pin substantially corresponds to the outer diameter of the coupling pin. The insertable in the coupling pin portion of the extension pin a robust mounting of the extension pin is achieved in the coupling pin. Since the outer diameter of the other portion of the extension pin, which extends beyond the tibial end of the coupling pin corresponds to the outer diameter of the coupling pin, no special modifications of the inlay, in particular the bore of the inlay are required.

The connection of the extension piece with the tibiaseitigen end of the coupling pin can be done by screwing the extension piece with the coupling pin, by jamming or by locking. These connections can be made easily by the surgeon during the operation.

In this case, the extension piece and / or the coupling pin may have a screw lock, in particular a transverse bolt, adhesive or a counter-locking screw. As a result, a loosening of the screw connection of the implanted prosthesis is prevented.

The required coaxiality of the coupling pin and the extension piece or the extension pin is achieved in that the bore in the tibial end of the coupling pin and the extension pin each have complementary, in particular cylindrical or conical, centering.

In a further preferred embodiment of the invention, the inlay comprises a sleeve body which in use extends substantially in the direction of the tibial axis, the position of the tibial end of the extended coupling pin and the position of the tibial end of the sleeve body substantially corresponding to one another. This means that the extended coupling pin extends substantially through the entire inlay as well as the entire sleeve body, so that extending in the direction of the tibial axis longitudinal extent of the inlay and the sleeve body connected thereto as completely penetrated by the coupling pin and thus in terms of stable storage of Coupling pin is used in the tibia part.

The prosthesis set according to the invention provides several, in particular at least two extension pieces of different lengths, so that the surgeon can choose between different extension pieces depending on the physiognomy of the respective patient during the operation.

With regard to the modular knee joint endoprosthesis, the connection between the coupling part and the separate coupling pin can take place in that the coupling part has a connecting pin with an external thread and the separate coupling pin each have a corresponding bore with an internal thread. Conversely, the coupling part can also have a bore with an internal thread and the separate coupling pins each have a corresponding connecting pin with an external thread. To connect the coupling part with the coupling pin of the respective connecting pin is screwed into the corresponding hole. Because differently long coupling pins are provided in the context of the invention, the operating doctor can select a suitably long coupling pin during the operation and screw it to the coupling part.

A loosening of the coupling part and the coupling pin can be avoided that the coupling part and / or the coupling pin has a screw lock, in particular a transverse pin and / or adhesive or a counter-locking screw.

In the following, the invention will be explained in more detail by means of embodiments with reference to the attached schematic drawings.

Show it

1 an exploded view of a knee joint endoprosthesis according to the prior art;

2 a ventral-dorsal vertical section through a tibial segment, a tibial component and a femoral component and an inlay upon insertion of the prosthesis 1 ;

3 one of the 2 corresponding representation with inserted femur part and inlay;

4 a schematic plan view of the support surface of the tibial plateau of the prosthesis after 1 ;

5 a dorsal exploded view of an embodiment of the knee joint endoprosthesis according to the invention;

6 a ventral exploded view of the prosthesis after 5 ;

7 a section through a prosthesis after 5 ;

8th a sagittal section through the prosthesis 5 in an extended position;

9 a sagittal section through the prosthesis 5 in a bent position;

10 an isometric view of the prosthesis after 5 with cut tibia part and inlay in bent position

11 an isometric view of the prosthesis after 5 with cut tibia part in stretched position;

12 a sagittal section through the prosthesis 5 ;

13 a frontal cut through the prosthesis after 5 ; and

14a -G representations of the individual prosthesis components or of the prosthesis orders which are required in the course of the implantation in accordance with the procedure;

15a , b is a side view of the coupling part and the extension pin with cylindrical and conical centering; and

16a , b Side views of the coupling part and the separate coupling pin with different screw connections.

Subsequently, the basic structure of a knee joint endoprosthesis based on the EP 0 791 344 A2 Known prosthesis explained in the 1 to 4 is shown. All features of this known prosthesis are also disclosed in connection with the prosthesis according to the invention, wherein the prosthesis according to the invention additionally has an extendable coupling pin, which will be referred to in detail.

1 shows an exploded view of a knee joint endoprosthesis, which consists essentially of four assemblies: a femoral component 1 with a femur shaft 3 and at its lower end arranged convexly curved Kondylenschalen 5 . 7 , which are largely adapted to the natural condyles and on their underside first sliding surfaces 9 . 11 and the dorsal two spaced sidewalls 13 . 15 that with a bridge to a box 39 are connected and inside the box 39 form an intercondylar space. The two condylar shells 5 . 7 go ventrally into each other and form a patellar image there 37 for articulation with the patella.

The counterpart to the feminine judgment 1 is a tibia part 2 with a tibial shaft 4 and a tibial plateau 6 at its upper end, which is a wing 36 having one extending axially in the tibial shaft 4 extending recess 12 as well as a side board 33 for receiving a third module 31 having.

This third assembly 31 consists of an inlay with a bottom surface 34 to rest on the wing 36 of the tibia part 2 , with one at the bottom surface 34 attaching sleeve body 35 which is used to attach the inlay 31 on the tibia part 2 into the recess 12 of the tibia part 2 is plugged, also with second sliding surfaces 8th . 10 on the top of the inlay 31 , which are concavely curved in a ventral-dorsal direction and on which the condyle shells 5 . 7 of the femdom 1 support. For fastening the fourth module, the coupling part 14 , on the tibia part 2 has the inlay 31 a hole 32 which extends through the top of the inlay and through the sleeve body 35 extends.

The coupling part 14 has as a central element a coupling pin 16 and at its upper end into the intercondylar space of the femoral part 1 protruding condyle 18 on. In the assembled state of the knee joint endoprosthesis is the coupling pin 16 in the hole 32 of the inlay 31 and thus in the recess 12 of the tibia part 2 rotatably received. The condyle 18 has a transverse to the tibial axis 20 or transverse to the femoral axis 21 extending bore 22 and is by means of a coupling pin 24 about a substantially horizontal hinge axis 29 swiveling in the side walls 13 . 15 the condylar shells 5 . 7 stored. The hole 22 in the condyle 18 has a sliding surface 30 which is shaped so that it has a bearing seat for a sliding sleeve 26 forms in the assembled state of the knee joint endoprosthesis between the coupling pin 24 and the condyle 18 arranged, ie with their bore 38 on the coupling pin 24 is plugged. In the in 1 illustrated embodiment, the sliding sleeve has a spherical outer surface 28 on that with the accordingly shaped sliding surface 30 of the condyle 18 cooperates and a division of the articular surfaces on the cylindrical coupling pin 24 and the spherical sliding sleeve 26 allows: the cylindrical coupling pin 24 only adopts the flexion / extension movement between the coupling pin and the sliding sleeve, while the spherical sliding sleeve 26 both the varus / valgus movement and a rotational movement between sliding sleeve and condyle takes over. The outer circumferential surface 28 Of course, it could also have any other convenient form. To reduce wear between the side surfaces 23 . 25 of the condyle 18 on the one hand and the rotating side walls on the other hand 13 . 15 the condylar shells 5 . 7 on the other hand, slices 17 . 19 provided, which also on the coupling pin 24 are plugged.

2 shows a ventral-dorsal vertical section through an upper tibial segment 50 , one in the tibia section 50 inserted tibial component 4 and a femoral part set for insertion (coupling together) 3 with an inlay 31 , The coupling part with the coupling pin 16 and the condyle 18 is by means of the above with reference to 1 described coupling pin mounted in the intercondylar space and about a pivot axis 29 pivoted. Already on the coupling pin 16 attached is the inlay 31 with the sleeve body 35 ,

On the basis of this vertical section through the tibia part it can be seen that the recess 12 , which with a first part axially in the tibial shaft 4 extends, in another part 46 from bottom to top to anterior (in the illustration on the left) enlarged divergently. The anterior inner edge 43 the recess 12 thus runs obliquely from the depth of the recess in the direction of the tibial plateau 6 , The by this divergent shaping of the recess 12 created additional space 46 , which runs essentially from posterior to anterior, allows even with longer coupling pin 16 an intraoperative insertion of the femur 3 and the inlay 31 without the need for overstretching of the knee ligament structures or even detachment thereof.

By the axial part of the recess 12 in the tibia part 2 is drilled a bit deeper than the divergent part 46 , ends the onset of the femdom 3 and the inlay 31 with an axially directed lowering of the inlay into the tibial plateau 6 , where a perfect fit of the inlay 31 with the side board 33 the wing 36 of the tibial plateau 6 is achieved. By the sleeve body 35 of the inlay 31 substantially complementary to the inner shape of the diverging recess 12 of the tibia part 2 is formed, the insertion ends further with a perfect fit of the sleeve body 35 with the recess 12 ,

3 shows the final state after insertion. On the basis of this representation it can be seen that the oblique anterior inner edge 43 the recess 12 with a tangent 44 to a circular arc 45 around the pivot axis 29 of the condyle 18 which coincides at an angle zur to the tibial axis 20 is inclined.

4 shows a schematic plan view of the tibial plateau 6 and illustrates the shape of the recess 12 , This consists of an axial part 40 and a diverging part 46 , where the divergent part 46 from the axial part 40 in the anterior direction (in the illustration above) extends. In the illustrated embodiment, the recess has 12 in the depth of their extension in the tibial shaft 4 a substantially circular symmetric cross-sectional shape extending toward the tibial plateau 6 to the cross-sectional shape of a slot 41 developed. Of course, other cross-sectional shapes of the lower part of the recess 12 conceivable, for. As square, polygonal, oval or rectangular. Optionally, it may be advantageous, the side walls 47 . 48 the recess 12 also diverging from bottom to top, as in 4 is shown by dashed lines, both to the anterior and to the tibial plateau, so that a trapezoidal cross-sectional shape of the recess 12 arises.

The achievable with the described knee joint endoprosthesis gentle coupling of the prosthesis parts provides that initially the inlay 31 by attaching to the coupling pin 16 with the femdom 3 is connected, and then these two components by the in 2 shown oblique approach to the tibial component 2 be used.

The structure of the prosthesis explained above is also in the in the 6 to 14 realized knee joint endoprosthesis according to the invention. However, it is also possible to choose a different prosthesis structure, provided that the coupling pin connecting the femoral component with the tibial component can be extended.

As in particular in 5 illustrated, the knee joint endoprosthesis according to the invention comprises a femoral component 1 , a tibia part 2 and an inlay 31 that in the 1 to 4 correspond respectively described components. The femur judgment 1 is with the coupling part 14 rotatably connected through the bolt 24 through which the condyle 18 of the coupling part 14 is rotatably mounted ( 7 to 9 and 12 . 13 ). The condyle 18 is with the coupling pin 16 one piece connected, in particular in 7 shown. Other connection possibilities between the coupling pin 16 and the condyle 18 , For example, a screw, are conceivable.

As in the 5 to 13 is shown, is the coupling pin 16 an extension piece 100 assigned, the present as an extension pin 101 is trained. Other types of extension of the coupling pin 16 For example, a telescopic extension are possible and are encompassed by the invention. The extension pin 101 may end with the tibia 16a the coupling pin 16 get connected. This includes the extension pin 101 two sections 102 . 103 with different outside diameters. The smaller diameter of the section 102 ie the femoralitigen section 102 , corresponds essentially to the inner diameter of the bore 104 that ends in the Tibetan side 16a the coupling pin 16 is provided so that the femurseitige section 102 into the hole 104 can be used. The hole 104 is with an internal thread and the femurseitige section 102 of the extension pin 101 is provided with an external thread, so that the extension pin 101 into the hole 104 the coupling pin 16 can be screwed.

It is also possible to have a lock nut on the extension pin 101 provided by the extension pin 101 in different screw-in depths with the coupling pin 16 can be locked. As a result, an even more flexible handling of the implant according to the invention is possible.

The adjustment of different lengths of the coupling pin can also by providing different extension pin 101 done with different lengths. In this case, in particular, the axial extent of the tibiaseitigen section 103 be varied with the larger outer diameter. The outer diameter of the tibial side section 103 corresponds to the outer diameter of the coupling pin 16 so that the extension creates a pin having a substantially constant outer diameter.

The extension pin 101 can also be through one in the hole 104 provided latching device with the coupling pin 16 locked or jammed. Generally, it is important that the extension pin 101 and / or on or in the coupling journal 16 Means are provided which provide a connection of the extension pin 101 with the coupling pin 16 enable.

The length of the extended coupling pin 16 should be essentially the length of the inlay 31 in the direction of the tibial axis in order to obtain the best possible support. It should be noted that the inlay 31 with the sleeve body 35 is connected, wherein the sleeve body 35 with the inlay 31 provided opening 104 flees. That means the length of the extended hitch pin 16 ie the length of the protruding part of the extension pin 101 and the coupling pin 16 should be chosen so that the location of the Tibetan end 16a the coupling pin 16 and the location of the Tibetan end 35a of the sleeve body 35 In essence, they correspond to each other. That means the thickness of the inlay 31 can be varied, with a suitable choice of the extension pin 101 is achieved that the extended coupling pin 16 the inlay 31 and the sleeve body 35 almost completely asserted. In this way, a particularly good support of the coupling pin 16 in the inlay 31 as well as in the tibia part 2 achieved, causing damage due to deformation of the inlay 31 and subsequent dislocation are minimized.

The following is the procedure of an implantation on the basis of 14a to g and the prosthesis components required according to the procedure described. In step 1 ( 14a ) first becomes the tibial component 2 implanted. Then the extension pin 101 on the in the femdom 1 preassembled and rotatably mounted coupling pin 16 mounted, in particular in the coupling pin 16 screwed. The mounting direction is in 14b indicated by an arrow. Then the femdom becomes 1 with the extended coupling pin 16 implanted, and the polyethylene inlay 31 introduced ( 14c ). Then the PE inlay 31 into the tibia part 2 introduced and the kingpin 16 with the screwed extension pin 101 into the PE inlay 31 coupled in ( 14d ). This operation step is to be carried out with bent leg position. Then the leg and thus the prosthesis is stretched and the titanium clip 105 in the inlay 31 used, so the inlay 31 with the tibia part 2 is fixed ( 14e . 14f ). The implanted knee joint endoprotesis is in 14g shown.

By providing several extension pins 101 , which are different in length per se, the doctor will be given even more variation options, which can decide during the operation, whether the extension of the coupling pin 16 should be a little shorter or a little longer. As a result, higher or thicker inlays can be used to compensate for a too weak ligament tension of the cruciate ligaments and to prevent the risk of dislocation. In the context of the invention, the term "extensible coupling pin" means that generally the length of the Coupling pin is changeable, which for example by connecting the coupling pin with the extension piece 100 can be done. The coupling pin 16 may also be extendible per se, ie be telescopic, for example. The possibility of the kingpin 16 To extend also includes the use of the coupling pin in the original, not extended version. That is, the coupling pin 16 can also do without the extension piece 100 be used, with the possibility in principle, the coupling pin 16 to extend, as this has a holding means in the form of the threaded bore, the assembly of the extension piece 100 serves.

In the 15a . 15b as well as in the 16a . 16b Further embodiments are shown, by which an intra-operative extension of the coupling pin and thus an intra-operative adjustment or adjustment of the ligament tension of the respective patient is made possible. In the in the 15 and 16 illustrated embodiments, the extension of the coupling pin is realized in particular by the modular structure of the coupling part, wherein in the embodiments of the 15a . 15b the extension piece described above 100 as a modular component and in the 16a . 16b the coupling pin 16 per se is provided as a module component.

The extension piece 100 is in the embodiment of the 15a . 15b designed as a screw, wherein the head of the screw in the screwed state, the extension of the coupling pin 16 forms. For screwing in the extension piece 100 or the screw has these a hexagon socket. The two screws after the 15a and 15b differ in that the screw after 15a a cylindrical centering section 107 and the screw behind 15b a cone-shaped, in particular frusto-conical, centering section 107 having. The two holes 104 in the coupling pin 16 are formed with complementary, ie cylindrical or conical centering 106 Mistake. This will ensure that the connector 100 and the coupling pin 16 coaxially aligned in the screwed-in state.

By providing different screws with different head heights different lengths of the coupling pin 16 be set individually during the operation.

An unintentional loosening of the screw from the coupling pin 16 is prevented by a screw lock. This threadlocker may comprise, for example, a cross-bolt made of polyethylene, which is transverse to the longitudinal extent of the coupling pin 16 the coupling pin 16 and the extension piece 100 or the screw penetrates. Alternatively or additionally, the screw with the coupling pin 16 be glued. Another way of securing the screw provides the use of a grub screw, which is used as a counter screw by one in the connector 100 provided axial bore is screwed and clamped.

Another way, the length of the coupling pin 16 to vary is in the 16a and 16b shown. Here is the coupling part 14 designed so that the coupling pin 16 and the condyle of the coupling part 14 represent separate components that are bolted together. In this case, various coupling pins are in the invention 16 provided with different lengths, in order to achieve that the overall length of the coupling part 14 in the axial direction, that is variable in Tibiarichtung.

For connecting the coupling pin 16 with the coupling part 14 is the condyle of the coupling part 14 with a connecting pin 108 equipped, which has an external thread. In the coupling pin 16 is an axial bore 109 provided with an internal thread into which the connecting pin 108 is screwed in. To screw in points the coupling pin 16 in the hole 109 opposite end a hexagon socket on, as in 16a shown.

As an alternative to this screw can also in the coupling part 14 , in particular in the condyle of the coupling part 14 a hole 110 be provided, in which the connecting pin 111 of the coupling pin 16 can be screwed. The connecting pin 111 is coaxial with the coupling pin 16 arranged. The coupling pin 16 also has a hexagon socket in this embodiment to the screwing and fixing of the coupling pin 16 to facilitate.

The two in the 16a and 16b illustrated embodiments may also be provided with threadlockers.

Furthermore, all features of the knee joint endoprosthesis according to 1 to 4 also in connection with the embodiments of the 15a . 15b . 16a and 16b disclosed.

The invention is described above with reference to embodiments with a fixed feature combination. However, it also includes the conceivable further advantageous combinations of these features, as they are given in particular, but not exhaustive, by the subclaims. All disclosed in the application documents features are claimed as essential to the invention, as far as they are new individually or in combination over the prior art.

LIST OF REFERENCE NUMBERS

1

femur

2

tibial component

8, 10

sliding surfaces

14

coupling part

16a

tibial end of the coupling pin

16

kingpin

31

inlay

32

Opening in the inlay

35

sleeve body

35a

Tibetan end of the sleeve body

100

extension

101

extension pin

102, 103

Sections of the extension pin with different outside diameters

104

Bore in the tibial end of the coupling pin

105

titanium clip

106, 107

centering

108

connecting pins

109

Bore in the coupling pin

110

Connecting pin on the coupling pin

111

Bore in the coupling part

Claims (14)

Knee joint endoprosthesis with a femoral component ( 1 ); a tibia part ( 2 ), that with the Fem judgment ( 1 ) is pivotally connected; an inlay ( 31 ) in use between the femur ( 1 ) and the tibial component ( 2 ) is arranged and at least one sliding surface ( 8th . 10 ) for the feminine judgment ( 1 ) forms; and a coupling part ( 14 ), that with the Fem judgment ( 1 ) is rotatably connected and a coupling pin ( 16 ) in use through an opening ( 32 ) in the inlay ( 31 ) extending into the tibial component ( 2 ) protrudes at least partially, characterized in that the coupling pin ( 16 ) is renewable. Knee joint endoprosthesis according to claim 1, characterized by an extension piece ( 100 ), with the tibial end ( 16a ) of the coupling pin ( 16 ) is connectable; Knee joint endoprosthesis according to claim 2, characterized in that the extension piece ( 100 ) an extension pin ( 101 ), the two sections ( 102 . 103 ) having different outer diameters, the section ( 102 ) with the smaller diameter in a bore ( 104 ) in the Tibetan end ( 16a ) of the coupling pin ( 16 ) and the larger diameter of the other section ( 103 ) substantially the outer diameter of the coupling pin ( 16 ) corresponds. Knee joint endoprosthesis according to claim 2 or 3, characterized in that the extension piece ( 100 ) with the coupling pin ( 16 ) is screwed. Knee joint endoprosthesis according to claim 4, characterized in that the extension piece ( 100 ) and / or the coupling pin ( 16 ) have a screw lock, in particular a transverse bolt, adhesive or a counter-locking screw. Knee joint endoprosthesis according to claim 2 or 3, characterized in that the extension piece ( 100 ) with the coupling pin ( 16 ) is clamped. Knee joint endoprosthesis according to claim 2 or 3, characterized in that the extension piece ( 100 ) with the coupling pin ( 16 ) is latched. Knee joint endoprosthesis according to claim 3 and one of claims 4 to 6, characterized in that the bore ( 104 ) in the Tibetan end ( 16a ) of the coupling pin ( 16 ) and the extension pin ( 101 ) each complementary formed, in particular cylindrical or conical, centering ( 106 . 107 ) exhibit. Knee joint endoprosthesis according to one of claims 1 to 8, characterized in that the inlay ( 31 ) a sleeve body ( 35 ) extending in use substantially in the direction of the tibial axis, the position of the tibial end ( 16a ) of the extended coupling pin ( 16 ) and the position of the Tibetan end ( 35a ) of the sleeve body ( 35 ) substantially correspond to each other. A prosthetic kit comprising a knee joint endoprosthesis according to one of claims 1 to 9 and at least 2 extension pieces ( 100 ) with different lengths. Knee joint endoprosthesis with a femoral component ( 1 ); a tibia part ( 2 ), that with the Fem judgment ( 1 ) is pivotally connected; an inlay ( 31 ) in use between the femur ( 1 ) and the tibial component ( 2 ) is arranged and at least one sliding surface ( 8th . 10 ) for the feminine judgment ( 1 ) forms; and a coupling part ( 14 ), that with the Fem judgment ( 1 ) is rotatably connected and a coupling pin ( 16 ) in use through an opening ( 32 ) in the inlay ( 31 ) extending into the tibial component ( 2 ) protrudes at least partially, wherein the coupling part ( 14 ) is modular, characterized in that separate, each of different lengths and / or individually extendable coupling pin ( 16 ) are provided. Knee joint endoprosthesis according to claim 11, characterized in that the coupling part ( 14 ) a connecting pin ( 108 ) with an external thread and the separate coupling pin ( 16 ) a corresponding hole ( 109 ) have an internal thread. Knee joint endoprosthesis according to claim 11, characterized in that the coupling part ( 14 ) a hole ( 110 ) with an internal thread and the separate coupling pin ( 16 ) a corresponding connecting pin ( 111 ) have an external thread. Knee joint endoprosthesis according to claim 12 or 13, characterized in that the coupling part ( 14 ) and / or the coupling pin ( 16 ) has a screw lock, in particular a transverse bolt, a counter-locking screw and / or adhesive.

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