DE4331282A1 - Joint endoprosthesis - Google Patents

Abstract

In a joint endoprosthesis, in particular for small joints, with a head member having an articular head and a cup member having a socket, the articular head is mounted so as to be pivotable with at least one degree of freedom in the socket. The head member can be moved in engagement with the cup member essentially transversely relative to its longitudinal axis. The head member is integrally formed and is held in the cup member, which is composed of two components, so as to be secured against withdrawal in the direction of its longitudinal axis. The two prosthetic members can be joined after a lateral deflection movement of at least one prosthetic member. A first component of the cup member having the socket is movable in engagement with a second part of the cup member after insertion of the articular head in the socket by a movement which is essentially perpendicular to the longitudinal axis of the head member. The articular head can be inserted in the socket essentially perpendicular to the longitudinal axis of the head member. At least one component of the cup member has a lateral insertion opening for the articular head. The insertion opening is closable. It can be closed by a relative movement between the components of the cup member. The insertion opening has elastically resilient lateral borders. The opening width of the insertion opening at one point at least is slightly smaller than the corresponding lateral profile of the articular head or of a basic member of the head member.

Description

The invention relates to a joint endoprosthesis, in particular for small joints, with a joint head Headboard and with a pan having a joint socket part in which the joint head with at least one free Degree of security is pivotally mounted in the socket. The The invention further relates to a kit for such a joint endoprostheses.

When implanting joint endoprostheses of the beginning mentioned type as a replacement for pathologically changed or incurable destroyed large joints, such as hip joints, can be after inserting a stem of the head part into a tube bones, for example in the femur, and after a ver anchor the pan part, for example in the pool, by off pull each other together with the two prosthesis parts Body parts the surrounding tissue in the area of the implantation stretch so far that it is possible to advance the joint head a socket opening facing the head part of the socket then bring it in the longitudinal direction of the headboard through the Insert the pan opening into the socket.

In contrast, most smaller joints, for example such an implantation for finger or toe joints procedures are not always applicable, since there the surrounding tissue cannot be stretched so much that insertion of the Ge steering head through the socket opening into the socket is. In the case of joint endoprostheses, the one mentioned at the beginning should also be used Kind prefers a so-called early mobilization the movements of the joint provided with the endoprosthesis before regeneration of the ligaments. This requires funds provided to catch the joint head in the socket to absorb any pull-out forces that may occur. At the known joint endoprostheses, in which the joint head is inserted through the socket opening into the socket, these are often stops in the case of a one-piece head part rings or the like after insertion of the joint  head into the socket around the base of the condyle are screwed to the pan part (DE 32 00 340 C2) in order thereby closing the pan opening so far that an off pulling the joint head is prevented. This increases however both the number of individual components of the prosthesis also the duration of the intervention during implantation.

Proceeding from this, the invention is based, ei to develop a joint endoprosthesis of the type mentioned at the beginning, where the joint head does not pass through the socket opening the socket must be inserted and, if desired, in the socket can be caught without the number of To increase prosthesis parts and / or the duration of an intervention eat. The invention is also based on the object To develop kit for such joint endoprostheses, the needs as few components as possible.

With regard to the joint endoprosthesis itself, this is on according to a first alternative embodiment of the Erfin tion solved in that the headboard is substantially transverse to brought into engagement with the pan part in its longitudinal direction can be. Because the headboard from the side with the Pan part engages, can also with small Ge steer the two prosthesis parts after connecting with each because remaining bone part easily by a ver relatively small lateral deflection movement of one or both Connect prosthesis parts together. Another advantage is that the resection length required to insert the Shaft of a prosthetic part is required, proportionately can be kept small and that an exact fit of the Prosthesis parts is facilitated.

Articular endoprostheses with those listed in claim 1 Features include both endoprostheses in which the Articular head is captured in the socket, as well as sol che, in which the socket is essentially the joint head hemispherical encloses without him in the direction of the longitudinal axis the headboard, d. H. in the axial direction against pulling out to back up.  

Merging the head and pan part is according to a preferred embodiment of the invention thereby possible light that the condyle essentially transverse to the longitudinal axis the head part can be inserted into the socket.

In contrast, a second alternative embodiment of the Invention before that the headboard is integrally formed and not extendable in the direction of its longitudinal axis in the from two Share existing second prosthesis part is captured. A Such a joint endoprosthesis can be used on the one hand with the realize the first alternative embodiment of the invention, by the articulated head of the head part substantially transverse to the sen longitudinal direction through a side inlet opening in the Joint socket of the composed of the two parts and in Bone anchored or held on the socket part to be led.

On the other hand, it is with regard to the second alternative off Design of the invention is also conceivable, the joint head of the headboard before completion of the Pro these into a first part of the Insert pan part and then this part, e.g. B. by means of a swiveling movement around the joint head with two already attached or anchored to the bone to bring part of the pan part. Capturing the joint In principle, the head can go through both the first and the first done by the second part, d. H. by the joint head flat if from the side through an insertion opening into the first Part is inserted, or by opening the pan from the second Part is formed and has an opening cross section that smaller than the corresponding maximum cross-sectional dimensions against the joint head.

Both alternatives therefore have the advantage that one Joint endoprosthesis with a captured joint head made of only two or three parts can be made.

A loosening of the completed articulation against the Direction of movement when merging can be according to one further preferred embodiment of the invention thereby ver  prevent the head part from being held by the pan part into the locked and / or snapped into it.

For example, an exit of the joint head from the Ge steering pan through the side insertion opening be changed that the insertion opening according to an advantageous Embodiment of the invention is designed closable, before preferably by a relative movement between the parts of the Pan part. It sees a further advantageous embodiment tion of the invention that the pan part a head cap and an inlay inserted into a recess in the head cap points, the inlay in such a way in the recess of the head cap Is rotatable that the insertion opening in an insertion position opened and at least partially in a locking position is closed. Both the head expediently cap as well as the inlay a side insertion opening where at the two insertion openings in the insertion position with each other align and at least partially in the locking position point in different directions.

Additionally and alternatively, it is possible to change the shape of the Insertion opening in the from a physiologically inert art choose existing material inlay so that the opening width is slightly smaller than the corresponding side Profile of the joint head, so that the lateral boundaries the insertion opening when inserting the joint head under Spread the pressure elastically and again behind the joint head move towards each other when this is in the socket located. The joint head snaps into the joint, so to speak the second part of the prosthesis.

To ensure that the joint head in the socket is captured, sees a further preferred embodiment the invention that the pan opening one against the Cross-sectional dimensions of the joint head with a smaller opening has cross-section, so that through the side insertion rod end inserted into the joint socket the pan opening can escape. The pan opening around preferably closes the head part in the area of a base partly of the joint head, the much smaller cross-section  measurements than the joint head itself and when inserting of the joint head through the side insertion opening of the second Part of the prosthesis through an insertion opening with the cups insertion slot connecting the opening into the pan opening voltage is pushed.

A further advantageous embodiment of the invention provides before that the joint head integrally with an intram dullary cavity of a tubular bone ver is bound, which advantageously on the joint head facing end through a face against the long bones adjacent collar is limited.

To prevent all three items of the fiction according to the joint endoprosthesis in different lengths see a further embodiment of the invention with regard to the kit that for one in each bone anchorable or attached to the bone second part of the Pan part several first provided with a joint socket Parts with different wall thicknesses between the joint pan and a limb supported against the first part tion area are provided. That is the distance between egg ner contact surface of the socket part facing the bone and the pivot point or the axis of rotation of the socket is thereby variable that the first part, which has the socket, different on its side facing away from the head part Has wall thicknesses. All of the first parts are preferred as an inlay, but with different lengths and each optionally in a cylindrical recess in the only one Head cap can be used. However, it is also possible to get the total to vary the length of the joint endoprosthesis in that the Head cap in the direction of the longitudinal extension of the total joints prosthesis is extended.

Alternatively or in addition, e.g. B. for fine tuning it is also conceivable that the kit at least one distance has holder that between the first and the second part can be used. The spacer is useful as Di stamped disc formed between the inlay and the bottom  the cylindrical recess and the inlay in their Location is held.

In many cases, however, the torque of those parts should be kept as small as possible, above the condyle are attached. These parts could be when rotating a large egg moves around a center of the condyle develop genetic dynamics.

For this reason, a further preferred embodiment of the invention is based on the fact that the joint head itself is raised above an upper edge of the bone in which the shaft carrying the joint head is anchored. Such an adjustment can be made with the help of an extension or shortening of the collar 16 . For this purpose, it is equipped with various wall thicknesses and can therefore be equipped for the respective application. The thicker the Kra 16 is, the higher the joint head rises above the shaft part with which the joint is anchored in the bone.

In the following the invention with reference to one in the drawing illustrated example explained in more detail. Show it:

Fig. 1a and b side views from different Rich lines of an endoprosthesis according to the invention in the elbow joint between the humerus and a resected radius part;

Figs. 2a and b show longitudinal sections through the stent of Figure 1 with two different inlays.

3 shows a cross section through the fitting to the humerus Pfan nenteil along the line 3-3 of Figure 2 in insertion without the radius head..;

FIG. 4 shows a cross section corresponding to that of FIG. 3, but in the locking position;

Fig. 5 shows a longitudinal section through the socket part taken along the line 4-4 of FIG. 3;

Fig. 6 shows a further longitudinal section through an endoprosthesis with radius head and head cap and

Fig. 7 shows a further longitudinal section through an endoprosthesis of Fig. 1a and b with the possibility of an extension of the head part.

The endoprosthesis 1 shown in the drawing for an elbow joint consists essentially of a head part 2 with a shaft 6 which can be anchored in the intramedullary channel of the radius 4 and a joint head 8 projecting over the end of the shaft 6 , which rests in a socket 10 of one on the humerus 12 Pan part 14 is pivotally mounted with two degrees of freedom.

Between the shaft 6 and the joint head 8 includes the integrally formed head portion 2 abutting in a resection plane towards the free end face of the resected radius 4 Kra gen 16, as well as a in the direction of the longitudinal axis 18 of the pan member 2 protruding over the collar 16 the base part 20 which connects the joint head 8 to the collar 16 and, after inserting the endoprosthesis 1, reaches through a socket opening 22 of the socket part 14 facing the radius 4 .

The shaft 6 shown in FIGS . 2 and 6 has on its outer circumferential surface longitudinally extending recesses 15 so that it can be cemented in a rotationally stable manner in the intramedullary channel of the radius 4 . As an alternative to this, however, the shaft can also have an external thread or a surface structure that enables cement-free anchoring. The shaft 6 facing annular bone abutment surface of the collar 16 is flat, while the transition into the base part 20 tapering to the base part 20 tapers conically, so that tilting movements of 10 to 15 degrees are possible, such as when bending the forearm in Joint occur before the collar 16 strikes the socket part 14 .

The socket part 14 is composed of two parts, a head cap 24, the gefläche with a slightly concavely curved in a direction Appendices 26 on its side remote the head portion 2 at the Hume rus 28 so applied as to be displaced in a bend of the forearm on the humerus 28 is, and which has a cylindrical recess 30 , which is open on its side facing the head part 2 , so that the second part formed as an inlay 32 can be inserted into the recess 30 .

While the head cap 24 is preferably made of a titanium or Mo lybdenum alloy or ceramic, the inlay 32 in the present exemplary embodiment consists of a physiologically inert plastic material, preferably of elastic, resilient polyethylene.

The inlay 32 also has a cylindrical outer shape, the cross-sectional dimensions of which correspond to the cross-sectional dimensions of the recess 30 , so that it can be rotated relative to the same about an axis of rotation 34 after insertion into the head cap 24 . The inlay 32 inserted into the recess 30 is supported against the head cap 24 and, in the exemplary embodiments shown in FIGS. 1 to 4, bears against the bottom 38 of the cylindrical recess 30 with a circular end boundary surface 36 . The on entgegenge imposed side of the inlay 32 disposed socket opening 22 of the inlay 32 bounded by an inner surface 42 which tapers slightly to the joint socket 10, wherein the angle of inclination relative to the rotational axis 34 is somewhat larger angle than the inclination that the slightly conical Includes the peripheral surface of the base part 20 with the longitudinal axis 18 of the first prosthesis part 2 , so that the base part 20 does not yet bear against the inner surface 42 when the collar 16 strikes the inlay 32 . Thus, the socket part 14 is supported when striking the collar 16 , advantageously as far out as possible on its conically tapered collar side. The tilt angle between the longitudinal axes of the head and socket part 2 , 14 can be individually adjusted in that different inlays 32 are provided, the head part 2 facing the pan opening 22 surrounding the boundary surface have different inclination angles to the longitudinal axis 34 of the socket part 14 or as a stop serving, protruding beads of different distances or the same.

The joint socket 10 arranged in the interior of the inlay 32 is delimited on its side facing away from the socket opening 22 by a sliding surface 44 , the shape of which corresponds to a spherical segment which is somewhat larger than a hemisphere. Against the sliding surface 44 there is a corresponding de, approximately hemispherical sliding surface 46 of the joint head 8 after an implantation, the diameter of which is slightly smaller than the diameter of the socket 10 . In order to securely capture the joint head 8 in the joint socket 10, the socket opening 22 has cross-sectional dimensions that are considerably smaller than the diameter of the joint head. Between the inner edge 48 of the pan opening 22 and the sliding surface 44, the joint socket limited 10 by the pan opening 22 to inclined oblique shoulder 50, against which at a pulling out of the joint head 8 in the direction of the socket opening 22 is accordingly inclined between the edge the sliding surface 46 and the end of the base part 20 abuts circumferential shoulder surface 52 , so that the axial movement of the joint head 8 in the joint socket 10 is limited.

In order to connect the head part 2 when inserting the prosthesis 1 with the socket part 14 , both the head cap 24 and the inlay 32 each have a lateral insertion opening 54 and 56, respectively. The insertion openings 54 , 56 are arranged so that they are aligned with one another in an insertion position ( FIG. 3) and at least partially point in different directions after insertion of the joint head 8 and subsequent rotation of the inlay 32 about the axis of rotation 34 , so that a Lateral emergence of the joint head 8 from the socket 10 is prevented. While the shape of the inlet opening 56 of the inlay 32 essentially corresponds to the lateral profile of the joint head 8 and the base part 20 , the inlet opening 54 of the head cap 24 has straight lateral boundaries 58 , the distance between which is somewhat larger than the diameter of the joint head 8 . This makes it possible to use inlays 32 with different wall thickness between the sliding surface 44 of the joint socket 10 and the boundary surface 36 in a head cap 24 in order to different distances between the contact surface 26 of the head cap 24 on the humerus 28 and the sliding surface 44 or the To be able to compensate for the pivot point of the joint without including several head caps 24 in the endoprosthesis kit. In addition, the head cap 24 between the bottom 38 of the recess 30 and the contact surface 26 can be reinforced to extend the entire joint prosthesis. As a result, the distance between the floor 38 and the contact surface 26 is greater and thus the total length of the joint endoprosthesis is greater.

In addition, it is possible to vary the length of the head part 2 in that the collar 16 has a more or less large wall thickness. With increasing wall thickness of the collar 16 , the head part 2 protruding from a bone (not shown ), including the joint head 8 , the inlay 32 and the head cap 24 , becomes longer. In this way it is prevented that only the part of the endoprosthesis 1 is longer to compensate for differences in length, which performs 8 pivoting movements around an imaginary center of the joint head and thereby introduces not inconsiderable torques due to the moving mass into the endoprosthesis 1 .

In contrast, the opening width of the insertion opening 56 of the inlay 32 is at least at one point, for example in the region of the insertion slot 62 provided for the base part 20 between the socket opening 22 and the peripheral surface 60 of the inlay 32 , slightly smaller than the corresponding transverse dimensions of the side profile of the head part 2 , so that when inserting the Ge steering head 8 in the socket 10 a certain force must be brought up to push the insertion opening 56 apart by widening their lateral limits. After the entry of the joint head 8 into the socket 10 , these move due to the elastic restoring force of the plastic material towards each other again and thus hold the joint head 8 immovable in the lateral direction in the joint socket 10 firmly. The pushing in of the joint head 8 through a guide opening 56 of the inlay 32 can be somewhat facilitated by the fact that the insertion opening 56 or the insertion slot 62 tapers inwards slightly towards the socket 10 or the socket opening 22 and at the transition to Ge steering pan 10 or pan opening 22 has the smallest opening width.

Basically, the described "snapping" of the joint head 8 in the socket 10 is sufficient to secure it, so that an additional rotation of the inlay 32 relative to the head cap 24 is not absolutely necessary. Conversely, a twisting of the head cap 24 and inlay 32 would already be sufficient for itself to hold the joint head 8 in the socket 10 .

Since the base part 20 tapers towards the joint head 8 , and accordingly the socket opening 22 tapers towards the joint socket 10 , it is also conceivable, in some applications, to insert the joint head 8 without an elastic expansion of the insertion opening 56 by the two prosthesis parts 2 and 14 , where possible, are pushed apart or pulled apart by a small amount in the axial direction and then the base part 20 is pushed through the insertion slot 62 , the opening width of which in the direction of the head part 2 corresponding to the lateral dimensions of the socket opening 22 something is increasing. After insertion of the Ge steering head 8 into the socket 10 , the two parts of the prosthesis 2 , 14 are released , whereupon they move so far again in the axial direction until their sliding surfaces 44 , 46 abut one another. In this position, since the transverse dimensions of the base part 20 are larger than the opening width of the slot 62 , the joint head 8 is held in the socket.

Pulling out of the inlay 32 from the recess in the head cap 24 can be prevented in that the inlay 32 has a circumferential groove (not shown), in the locked position ( FIG. 4) at least one pin projecting inwards into the cylindrical recess the head cap 24 engages. Since the insertion of the inlay 32 into the recess 30 does not impede the insertion of the inlay 32 , the inlay 32 has on its outer circumferential surface 64 in the axial direction from the circumferential groove to the end boundary surface 36 extending longitudinal grooves which, in the insertion position ( FIG th fluch with the pins so that the inlay can be introduced in this position 32 in the recess 30. 3).

While a stocking of all the individual parts 2 , 24 , 32 of the joint endoprosthesis 1 in different lengths as already mentioned can be prevented by the fact that, as shown in FIGS. 2a and b, inlays 32 of different lengths, ie inlays 32 with different wall thicknesses between the Joint socket 10 and the boundary surface 36 alternatively used in a single head cap 24 , it is, as shown in Fig. 6 Darge, further possible to include only one head cap 24 and an inlay 32 for a certain application in a kit and additionally several spacers 70 with the same or different thicknesses, which can be inserted individually or in groups between the bottom 38 of the recess 30 and the loading boundary surface 36 of the inlay 32 . If conceivable, the inclusion of a plurality of inlays 32 of different lengths and a plurality of very thin spacers 70 , which are then inserted only for fine-tuning between the inlay 32 and the head cap 24 .

Finally, it is conceivable to enrich the kit with inlays 32 and head caps 24 of different heights. If, for example, the distance between the sliding surface 44 , the joint socket 10 and the boundary surface 36 of the inlay 32 is increased ver, the total length of the head part 2 of the endoprosthesis 1 protruding from the bone also changes. Another possibility to vary the length of this head part 2 is that the thickness of the head cap 24 between the Bo 38 and the contact surface 26 is increased. Through these measures, the mass of the upper half of the joint head 8 moving parts increases at the same time. As a result, not inconsiderable torques are introduced into the joint head 8 . In order to keep these dynamic forces as small as possible, an extension of the entire head part 2 can be brought about by either thickening the collar 16 or by interposing spacer rings between the collar and the adjacent edge of the bone into which the shaft 6 protrudes become.

Claims (34)

1. Joint endoprosthesis, in particular for small joints, with a head part having a joint head and a socket part having a joint socket, in which the joint head is pivotally mounted with at least one degree of freedom in the joint socket, characterized in that the head part ( 2 ) in is substantially movable transversely to its longitudinal axis ( 18 ) in engagement with the socket part ( 14 ). 2. joint endoprosthesis, in particular for small joints, with a joint head having a head part and with a Ge joint socket having socket part, in which the joint head of the head part is pivotally mounted ver with at least one degree of freedom, characterized in that the head part is formed in one piece and in the direction of its longitudinal axis ( 18 ) is not extendable in the pan component ( 14 ) consisting of two components ( 32 , 24 ). 3. A joint endoprosthesis according to claim 1 or 2, characterized in that the two prosthesis components (2, 14) according to a lateral deflection movement of at least one prosthesis part (2, 14) can be brought together. 4. Joint endoprosthesis according to one of claims 1 to 3, characterized characterized in that a first, having the socket Component of the socket part after insertion of the joint head into the socket through a substantially transverse to the longitudinal movement of the head part in engagement with an axis second part of the pan part is movable. 5. Joint endoprosthesis according to one of claims 1 to 4, characterized in that the joint head ( 8 ) can be inserted substantially transversely to the longitudinal axis ( 18 ) of the head part ( 2 ) in the socket ( 10 ). 6. Joint endoprosthesis according to one of claims 1 to 5, characterized in that at least one component ( 24 , 32 ) of the Pfan nsteils ( 14 ) has a lateral insertion opening ( 54 , 56 ) for the joint head ( 8 ). 7. Joint endoprosthesis according to claim 6, characterized in that the insertion opening ( 54 , 56 ) can be closed. 8. Joint endoprosthesis according to claim 6 or 7, characterized in that the insertion opening ( 54 , 56 ) can be closed by a relative movement between the components ( 24 , 32 ) of the socket part ( 14 ). 9. Joint endoprosthesis according to claim 8, characterized in that the insertion opening ( 54 , 56 ) can be closed by rotating the joint socket ( 10 ) having the component ( 32 ). 10. A joint endoprosthesis according to one of claims 6 to 9, characterized in that the insertion opening ( 54 ) has elastically flexible side limits. 11. A joint endoprosthesis according to claim 10, characterized in that the opening width of the insertion opening ( 56 ) is at least at one point slightly smaller than the corresponding profile since the joint head ( 8 ) or a base part ( 20 ) of the head part ( 2 ). 12. Joint endoprosthesis according to one of claims 6 to 11, characterized in that the insertion opening ( 56 ) and a Ba sisteil ( 20 ) of the head part ( 2 ) taper in the axial direction, so that the joint head ( 8 ) and the base part ( 20 ) after pulling apart the two prosthesis parts ( 2 , 14 ) in the axial direction through the insertion opening ( 56 ), the base part ( 20 ) after releasing the two prosthesis parts ( 2 , 14 ) from the boundaries of the insertion opening ( 56 ) is held in place. 13. Joint endoprosthesis according to one of claims 1 to 12, characterized in that the socket part ( 14 ) has a head cap ( 24 ) and in a recess ( 30 ) of the head cap ( 24 ) arranged inlay ( 32 ). 14. Joint endoprosthesis according to claim 13, characterized in that the inlay ( 32 ) is rotatably held in the recess ( 30 ). 15. A joint endoprosthesis according to claim 13 or 14, characterized in that the head cap ( 24 ) and the inlay ( 32 ) have a lateral insertion opening ( 54 , 56 ), and in that the inlay ( 32 ) relative to the head cap ( 24 ) can be rotated that the insertion openings ( 54 , 56 ) are aligned with each other in an insertion position and at least partially point in different directions in a locking position. 16. Joint endoprosthesis according to one of claims 13 to 15, characterized in that the joint socket ( 10 ) has de inlay ( 32 ) consists of a physiologically inert plastic material. 17. Joint endoprosthesis according to one of claims 13 to 16, characterized in that the inlay ( 32 ) consists of an elastically flexible plastic material. 18. Joint endoprosthesis according to one of claims 13 to 17, characterized in that the inlay ( 32 ) is made of polyethylene be. 19. Joint endoprosthesis according to one of claims 13 to 18, characterized in that the head cap ( 24 ) consists of a titanium or molybdenum alloy or ceramic. 20. Joint endoprosthesis according to one of claims 1 to 15, characterized in that a socket opening ( 22 ) of the socket joint ( 10 ) has a smaller opening cross-section than the maximum cross-sectional dimensions of the joint head ( 8 ). 21. Joint endoprosthesis according to claim 20, characterized in that the socket opening ( 22 ) communicates with the lateral insertion opening ( 56 ). 22. Joint endoprosthesis according to claim 20 or 21, characterized by an insertion slot ( 62 ) arranged between the insertion opening ( 56 ) and the socket opening ( 22 ). 23. Joint endoprosthesis according to one of claims 1 to 12, characterized in that the joint head ( 8 ) is integrally connected to a shaft ( 6 ). 24. Joint endoprosthesis according to claim 23, characterized by a collar ( 18 ) arranged between the base ( 20 ) of the joint head ( 8 ) and the shaft (6). 25. Joint endoprosthesis according to claim 24, characterized in that the collar ( 18 ) tapers conically on its side facing the socket part. 26. Joint endoprosthesis according to one of claims 1 to 25, characterized in that the joint head ( 8 ) in the socket ( 10 ) is pivotally mounted with a degree of freedom. 27. Joint endoprosthesis according to one of claims 1 to 25, characterized in that the joint head ( 8 ) in the socket ( 10 ) is pivotally mounted with two degrees of freedom. 28. Joint endoprosthesis according to claim 27, characterized in that that it replaces a radius head. 29. Kit for joint endoprostheses according to one of claims 2 to 25, characterized in that for a second construction part ( 24 ) of the socket part ( 14 ) several with a joint socket ( 10 ) provided first components ( 32 ) with different wall thicknesses between the Joint socket ( 10 ) and a limiting surface ( 36 ) which is supported against the second component ( 24 ) are provided. 30. Kit for joint endoprostheses according to one of claims 1 to 28, characterized by at least one between a second and a first component ( 24 and 32 ) of the socket part ( 14 ) a removable spacer. 31. Kit according to claim 29 or 30, characterized in that several inlays ( 32 ) are provided with different lengths, which can alternatively be used in a head cap ( 24 ). 32. Kit according to claim 31, characterized in that the spacer is formed as a spacer and can be inserted between the inlay ( 32 ) and the head cap ( 24 ). 33. Kit according to at least one of claims 29 to 32, characterized in that a plurality of head caps with different wall thickness between an inlay ( 32 ) receiving bottom ( 38 ) and a head cap ( 24 ) closing contact surface ( 26 ) are provided, which are alternative can be placed on the inlay ( 32 ) to compensate for lengths. 34. Kit according to at least one of claims 29 to 32, characterized in that a plurality of shafts ( 6 ) with different wall thicknesses of the collar ( 16 ) are provided, which can alternatively be used in a bone to compensate for differences in length occurring in the head part ( 2 ) and on the Ge steering head ( 8 ) the desired inlay ( 32 ) and the head cap ( 24 ) can be placed.