DE19745632C1 - Stemless knee joint prosthesis with swiveling tibia plateau - Google Patents

Description

The invention relates to a stemless knee joint prosthesis with a Femur part and a tibia part according to German patent application DE 197 28 636 C1, more precisely, an advantageous development of the same.

For diagnoses in which the two side ligaments and the posterior cruciate ligament are still largely intact, it can lead to unphysiological movements come due to the forces introduced by the ligaments.

The object of the present invention is to remedy this, d. H., to reproduce the movement even more physiologically.

This problem is solved by the knee joint endoprosthesis according to DE 197 28 636 C1, in which the Slides of the tibia part are formed in a plastic pad that around a pin embedded in the tibia part by an angle α in the area α <± 20 ° is pivotable about the rest position.

Assume the usual constellations of a tibia part artificial knee joint, in which a plastic pad is rigid with the mostly metallic other tibia part is connected, the present edition held pivotable around the mentioned pin. Preferably sits the Pin around which the plastic pad is pivotable, approximately in the center Middle part of the tibia part. The main axis of the peg runs from caudal to cranial.  

The solution according to the invention offers the possibility that the plateau or the Plastic pad can perform evasive movements, such as the Ligament forces during a flexion movement of the artificial knee joint are asymmetrical. In this case, the plateau swings with its Slides in the appropriate direction so that the artificial condyles of the femur part imitating a physiological movement of the natural knee joint can slide and roll on the slideways.

According to a preferred development, the swivel range is Plastic pad limited by a on the periphery of the contact surface of the Tibial parts at least partially encircling, the plastic pad with play edging and acting as a stop for this edge.

This training provides a high level of security against an uncontrolled Rotation of the plastic pad even under extreme conditions or Charges.

The invention is based on an embodiment according to the Drawing figure explained in more detail.

Here shows:

Fig. 1 shows the front view of a tibia part with a pivoted plastic pad, and

FIG. 2 shows a lateral medial section through the tibia part according to FIG. 1 and an indicated tibia bone.

Parts that correspond to those according to the main application are the same, however, designated by an apostrophe (').  

It is therefore not considered the common features with the Represent the tibia part according to the main application. Rather, the corresponding description parts of the main application.

In the present case, only the difference characteristics are discussed:

The two slideways 4 'and 5 ' are formed in the plastic support 2 '. In the center of the plastic support 2 ', it can be pivoted about a pin 30 (see FIG. 2) embedded in the tibia part 1 ', namely by an angle α in the range between -20 and + 20 ° from the central rest position. This makes evasive movements of the plastic support 2 'possible due to asymmetrically acting forces in the largely intact side ligaments and posterior cruciate ligament. The evasive movement means that the condyles of the femoral part can always roll on a maximum sliding and rolling surface. This enables an almost optimal physiological movement.

In the present case, the pivoting range of the plastic support 2 'is limited ( FIG. 2) by an edge 32 which at least partially surrounds the periphery of the support surface 31 of the tibia part 1 '. The edge 32 surrounds the plastic pad 2 'with play and acts as a stop for it. Among other things, the size of the game ultimately defines the pivoting range of the plastic support 2 '.

Bores 35 in the plastic support 2 'allow the entire joint to be flushed with the synovial fluid, the so-called synovia.

Moreover, in the embodiment according to FIG. 2 it is also provided that a central guide element 33 can be coupled to the centering pin 15 ′ formed on the tibia by means of a conical clamp 34 . In the present case, the guide element 33 is shown as an extension handle.

It is important to emphasize here that the guide element 33 does not act like a conventional stem endoprosthesis.

Claims (2)

1. Knee joint endoprosthesis according to the German patent DE 197 28 636 C1, in which the slideways ( 4 ', 5 ') of the tibia part ( 1 ') are formed in a plastic pad ( 2 ') which surrounds one in the tibia part ( 1 ') recessed pin ( 30 ) by an angle α in the range α <± 20 ° can be pivoted about the rest position. 2. Knee joint endoprosthesis according to claim 1, in which the pivoting range of the plastic support ( 2 ') is limited by an at least partially circumferential at the periphery of the support surface ( 31 ) of the tibia part ( 1 '), the plastic support ( 2 ') enclosing with play and as Stop acting edge ( 32 ).