DE10305795A1 - Joint element and implant - Google Patents

Abstract

Around a joint element of an implant for replacing at least a part of a joint formed by at least a first and a second bone end, the implant comprising a first implant element that can be arranged on the first bone end, a second implant element that can be arranged on the second bone end, and the joint element, wherein the hinge element comprises a first bearing surface bearing against the first implant element, a second bearing surface lying against the second implant element and a contact surface which is formed between a first edge region formed between the first bearing surface and the contact surface and between a between the second bearing surface and the contact surface The second edge region formed extends and can come into contact with the tissue surrounding the joint element, in order to improve such that the risk of injury to tissue surrounding the joint element is prevented with at least constant mobility, is proposed struck that the contact surface between the first and the second edge region has at least one contact surface region which, facing away from the joint element, is convexly curved on all sides. Furthermore, an implant with such a joint element is proposed.

Description

The invention relates to a joint element an implant to replace part of one of at least one first and a second bone end formed joint, which Implant a first implant element that can be arranged on the first bone end, a second implant element which can be arranged at the second bone end and comprises the joint element, wherein the joint element has a first, on the first implant element adjacent storage area, a second bearing surface resting on the second implant element and a contact area comprises which is between a between the first storage area and the contact surface formed first edge area and between one between the second bearing surface and the contact area formed second edge region extends and with the joint element surrounding tissue can come into contact.

The present invention further relates to an implant to replace at least a portion of at least one a first and a second bone end formed joint, with a first implant element that can be arranged on the first bone end, with a second implant element that can be arranged on the second bone end and with a joint element.

Implants with joint elements of the type described in the introduction are used as endoprostheses, for example to replace a knee joint. Depending on the natural joint surfaces destroyed by wear, it may be sufficient if only a part of the femur in the knee joint is replaced by a first implant element and part of the tibia by a second implant element. So that the most natural possible movement can be achieved, in addition to the two implant elements, a joint element movably mounted between them and usually abutting them is provided. This articulation element can move more or less freely between the two implant elements during articulation of the articulation. Freedom of movement is often restricted by guide means. If, however, no elements restricting the movement of the sliding element are provided, the joint element can strike the surrounding tissue during articulation, in particular in extreme articulation situations, for example with high flexion and / or superimposed rotation. This can cause irritation or injury to the soft parts surrounding the joint element if the contact surface and / or the edge regions of the joint element are angular, sharp or pointed, as is the case, for example, in FIG US 4,950,297 described endoprosthesis.

It is therefore the task of the present Invention a joint element and an implant of the type described above Art to improve so that at least constant mobility of the joint element the risk of Injury from tissue surrounding the joint element is prevented.

This task is done with a joint element of the type mentioned according to the invention solved in that the contact surface between the first and the second edge area at least one contact surface area has, which is convex on all sides facing away from the joint element. This means that the at least one contact area convex both in a circumferential direction of the contact surface and transversely thereto is curved. Through the at least one atraumatically shaped contact area there may be no irritation or injury to the surrounding implant Soft tissues come. Furthermore, when the joint element strikes first of all the convex curved bulbous wall section on the soft tissues of the at least one contact area contact the soft tissues so that neither the first nor the second edge area of the joint element come into contact with the soft parts can.

Cheap it is when the contact area two convexly curved surface areas has, in particular two, preferably in opposite directions looking. Especially when the joint element essentially is moved in the anterior-posterior direction, it may be sufficient if the contact area is formed atraumatically in two areas that point away from each other.

A particularly slim design of the joint element to enable it can be advantageous if the contact surface is at least one level area has, in particular two, preferably in opposite directions looking. In this way advantageously adapt the joint element to a first implant element which can be particularly narrow, for example an artificial one Femoral condyle.

Cheap it is when the contact area is edge-free. This will cause irritation and injury from that Tissue surrounding tissue avoided.

It is advantageous if a vertical projection of at least one cutting plane running essentially transversely to the contact surface completely covers the surface enclosed by the first edge region and if a vertical projection of the cutting plane completely covers the surface enclosed by the second edge region. This configuration ensures that the bulbous, convex-shaped contact surface protrudes on all sides over the two bearing surfaces, so that in each the case, the contact surface first comes into contact with the tissue surrounding the joint element.

According to a preferred embodiment of the Invention can be provided that a tangential plane to the contact area in the transition area to the first storage area with the first storage area encloses an angle the bigger than 90 °, in particular larger than Is 110 °. By forming an obtuse angle between the tangential plane and the storage area will ensure that too if there are any edges in the transition area between the contact area and the first storage area always the contact surface first comes into contact with tissue surrounding the joint element, whereby Injuries or irritation can be avoided.

It is also advantageous if a Tangential plane to the contact surface in the transition area to second storage area with the second storage area Includes angle, the bigger than 90 °, in particular larger than Is 110 °. This also ensures that tissue surrounding the joint element always only with the contact surface contacts before, if at all, contacting the bearing surface can come.

The joint element could be on can be realized in different ways, for example as a rolling element. Cheap it is, however, if the joint element is a sliding element and if the first and / or the second bearing surface are sliding surfaces. This will make the Number of moving parts on the implant and thus also on the joint element minimized because of the storage space are in direct contact with the implant elements.

To reduce the risk of injury from to reduce the tissue surrounding the joint element even further it cheap if a transition area of the first edge area between the contact surface and the first bearing surface in the circumferential direction of the first edge area rounded off at least in sections and is edge-free, preferably completely rounded and edge-free is.

It can also be beneficial be when a transition area of the second edge area between the contact surface and the second bearing surface in the circumferential direction of the second edge area rounded at least in sections and is edge-free, preferably completely rounded and edge-free is. This will reduce the risk of injury from the implant surrounding tissue further diminished.

The first edge area could in principle be completely flat be trained so that a touching the first edge area Level this along one touches a self-contained line. Very cheap it is, however, if the first edge area relates to the first Edge area touching contact plane concavely curved is. This results in a side view of the joint element pulled down edge areas, which on the one hand saves material and an overall width of the implant can be kept particularly small can.

So regardless of an articulation position optimal joint contact between the first implant element and the joint element guaranteed can be provided in a preferred embodiment of the invention, that the first storage area of the joint element has a concave shape pointing away from the joint element has, in particular a spherical shape. This enables one Sliding in all directions, so that it is too no tilting between the joint element and the first implant element comes.

A particularly simple training of the articulated element results when the second bearing surface of the Hinge elements has a flat shape. This allows the joint element to be relatively to the second implant element in the one defined by the second bearing surface Move the level as desired if there are no additional guide means on the implant components are provided.

It is particularly favorable if the contact surface is essentially has a ring shape. By such a bulged ring seen from above contact area can be ensured that the Tissue surrounding tissue is not injured.

A particularly slim one, to the two Customized implant elements The design of the joint element results when the ring shape is substantially oval.

Furthermore, the structure of the joint element is additionally simplified, if it has at least one plane of symmetry that is transverse to the second storage area runs.

The task at the beginning is furthermore according to the invention in the case of an implant of the type described at the outset solved, that this Joint element is one of the joint elements described above.

This helps ensure that overall no injuries or irritation from the implant due to the implant surrounding tissue can be caused.

The following description of a preferred embodiment the invention serves in conjunction with the drawing for a more detailed explanation. Show it:

1 a side view of a knee joint with an inserted, partially replacing the knee implant;

2 a view in the direction of arrow A in 1 ; and

3 a perspective view of a slide bearing of the implant in 1 ,

In the 1 and 2 is a whole with the reference symbol 10 shown provided implant, which is used as a partial knee joint endoprosthesis can be. It comprises two implant elements designed as anchoring elements, namely a femur part 12 and a tibia part 14 , as well as a plain bearing serving as a joint element 16 , The implant 10 serves in its entirety to an at least partially destroyed joint surface 18 one of two condyles 20 and 21 one from a femur 22 and a tibia 24 to replace the formed knee joint.

The tibia part 14 comprises an elongated cuboid bearing plate 26 , from the bottom 28 one in the longitudinal direction of the bearing plate 26 extending, also cuboid anchoring projection protrudes vertically. On their top 32 is on the bearing plate 26 a longitudinal bone cover extending in the longitudinal direction 34 arranged perpendicularly from the top 32 extends away and substantially parallel to the anchoring projection 30 is arranged progressively. Overall, this results in an L-shaped cross section of the bearing plate 26 with the bone cover 34 , On the leading edge 34 can also be dispensed with.

The bone cover 34 is primarily used for bone growth after insertion of the tibia part 14 to prevent. In addition, there may also be contact between the slide bearing 16 and the upper surface 32 of the abrasion and bone substance of the tibia 24 prevented. In a basic position of the plain bearing 16 such as in 2 is shown are the bone cover 34 and the plain bearing 16 spaced from each other. Only in extreme situations, i.e. with strong lateral movements of the plain bearing 16 , there may be contact with the plain bearing 16 and the bone cover 34 come.

For implanting the tibia part 14 becomes a the femur 22 facing tibia plateau 38 in the area of destroyed condyles 20 partially resected, leaving a flat tibial plane 42 with a lateral edge formed by remaining bone 42 remains. The tibia part 14 is fitted so that the bottom 28 the bearing plate 26 at the tibia plane 40 and the bone cover 34 on the edge 42 is applied. If necessary, the tibia part can also be cemented in place.

The femoral part 12 is used to replace an at least partially damaged condyle 20 which is partially removed for this purpose. The femoral part 12 includes one in the implanted state of the femur 22 pioneering spherical condyle surface 44 , On its back it is over an angular range of approximately 90 ° with a concave cylindrical surface 46 provided by a kink 48 from a flat contact surface 50 is separated.

For anchoring the femoral part 12 on the femur 22 becomes the condyle 22 corresponding to the cylinder surface 46 and to the contact surface 50 partially resected, so that the two surfaces mentioned 46 and 50 completely on the remaining femur 22 issue.

About a relative movement between the femur 22 and tibia 24 To enable in a defined way is the plain bearing 16 with a first, flat storage area 54 provided that on the top 32 the bearing plate can be moved freely 26. A second, towards the femur 22 pointing hollow spherical recess 56 forms a second bearing surface on which the condylar surface 44 part of the wall 12 can slide. The radius 58 the recess 56 corresponds to the radius 60 the spherical surface of the condyle 44 ,

A top margin 62 with a bottom edge 64 of the plain bearing 16 connecting wall surface 66 is divided into a total of four adjoining and merging areas, namely a front 70 , a back 72 , an inner side surface 72 and an outer side surface 76 , The front 70 and the back 72 are convexly curved on all sides, ie both a longitudinal and a cross section of the plain bearing 16 in the area of the front 70 and the back 72 forms one of the plain bearings 16 pointing boundary line. This creates a total of two edge-free, large, soft-shaped bulbous contact surfaces. A projection of the plain bearing 16 perpendicular to the storage area 54 covers this completely, the same applies to the vertical projection onto the recess 56 , A distance 68 between a point on the front most protruding from the front or back 70 or the back 72 from the lower or upper edge 64 . 62 lies in the range between 0.5 and 5 mm, preferably it is approximately 1.5 mm.

Both the top 62 as well as the bottom 64 are completely rounded, so that the plain bearing 16 forms an overall completely edge-free, rounded body. However, it is also conceivable that in transition areas between the front 70 and the back 72 to the inner and outer side surfaces 74 and 76 Edges are formed, since there is a soft tissue contact of the plain bearing in particular in these areas 16 is rather unlikely.

If the knee joint is articulated, the plain bearing may strike 16 with the front 70 and the back 72 come to soft parts, not shown. Due to the rounded design of the plain bearing 16 however, these soft tissues are neither irritated nor injured at the front and back. Basically, it is also possible to use the flat side surfaces 74 and 76 to do without and also these areas of the wall surface 66 from the plain bearing 16 pointing away to be convex on all sides.

Claims (17)

Joint element of an implant for replacing at least a part of a joint formed by at least a first and a second bone end, wherein the implant has a first, on the first th bone end to be arranged implant element, a second implantable to the second bone end implantable element and the joint element, wherein the jointed element comprises a first bearing surface adjacent to the first implant element, a second bearing surface adjacent to the second implant element and a contact surface which is between a extends between the first bearing surface and the contact surface and between a second edge region formed between the second bearing surface and the contact surface and can come into contact with tissue surrounding the joint element, characterized in that the contact surface ( 66 ) between the first and the second edge area ( 62 . 64 ) at least one contact area ( 70 . 72 ) which is from the joint element ( 16 ) is convexly curved on all sides. Joint element according to claim 1, characterized in that the contact surface ( 66 ) two convexly curved contact surface areas ( 70 . 72 ) has, in particular two, preferably pointing in opposite directions. Joint element according to claim 1 or 2, characterized in that the contact surface ( 66 ) at least one flat area ( 74 . 76 ) has, in particular two, preferably pointing in opposite directions. Joint element according to one of the preceding claims, characterized in that the contact surface ( 66 ) is edge-free. Joint element according to one of the preceding claims, characterized in that a vertical projection of at least one essentially transversely to the contact surface ( 66 ) the cutting plane running from the first edge area ( 62 ) completely covers the enclosed area and that the vertical projection of the cutting plane is that of the second edge area ( 66 ) completely enclosed area. Joint element according to one of the preceding claims, characterized in that a tangential plane to the contact surface ( 66 ) in the transition area ( 62 ) to the first storage area ( 56 ) with the first storage area ( 56 ) includes an angle that is greater than 90 °, in particular greater than 110 °. Joint element according to one of the preceding claims, characterized in that a tangential plane to the contact surface ( 66 ) in the transition area ( 64 ) to the second storage area ( 54 ) with the second storage area ( 54 ) includes an angle that is greater than 90 °, in particular greater than 110 °. Joint element according to one of the preceding claims, characterized in that the joint element is a sliding element ( 16 ) and that the first and / or the second bearing surface are sliding surfaces ( 54 . 56 ) are. Joint element according to one of the preceding claims, characterized in that a transition region of the first edge region ( 62 ) between the contact surface ( 66 ) and the first storage area ( 56 ) is rounded at least in sections in the circumferential direction and is edge-free, preferably completely rounded and edge-free. Joint element according to one of the preceding claims, characterized in that a transition region of the second edge region ( 64 ) between the contact surface ( 66 ) and the second storage area ( 54 ) in the circumferential direction of the second edge region ( 64 ) is rounded at least in sections and is edge-free, preferably completely rounded and edge-free. Joint element according to one of the preceding claims, characterized in that the first edge region ( 62 ) related to the first edge area ( 62 ) touching contact plane is concavely curved. Joint element according to one of the preceding claims, characterized in that the first bearing surface ( 56 ) of the joint element ( 16 ) one of the joint element ( 16 ) has a pointing concave shape, especially a hollow spherical shape. Joint element according to one of the preceding claims, characterized in that the second bearing surface ( 54 ) of the joint element ( 16 ) has a flat shape. Joint element according to one of the preceding claims, characterized in that the contact surface ( 66 ) has essentially a ring shape. Joint element according to claim 14, characterized in that the Ring shape is substantially oval. Joint element according to one of the preceding claims, characterized in that the joint element ( 16 ) has at least one plane of symmetry that is transverse to the second bearing surface ( 54 ) runs. Implant for replacing at least part of a joint formed by at least a first and a second bone end, with a first one that can be arranged on the first bone end Implant element, with a second implant element that can be arranged on the second bone end and with a joint element, characterized in that the joint element ( 16 ) is a joint element according to one of the preceding claims.