JPS6143471Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the improvement of the knee joint prosthesis described in Japanese Patent Application No. 133088/1983.

What is achieved by the solution in the above-mentioned patent application is that in each flexion position of the knee prosthesis, a limited rotation of the tibial joint relative to the femoral joint can be performed as in the real knee joint; Furthermore, the femoral joint can perform a limited forward movement relative to the tibial joint (which also occurs in the case of a real knee joint). The rotations and movements performed by the joint prevent excessive stretching of the muscles of the knee prosthesis. However, in the said patent application, the femoral joint has a fixation rod that protrudes into the femur, and the axis of the fixation rod is aligned with the joint formed between the medial and lateral condyles of the femoral joint. Because it is located in the vertical longitudinal center plane of the cavity, the patella housed within the patella band can move unhindered in the same way as the real patella (moves from upper and lateral to arched downward and medial). I can't.

Therefore, in the knee joint prosthesis of the patent application, the following measures are taken in this invention in order to enable the patella to perform the above movements. That is, the fixing rod provided on the femoral joint is shifted toward the lateral condyle with respect to the vertical longitudinal center plane of the joint space, and is fixed to the bridge-like connecting part of the femoral joint, and A sliding surface modeled after the knee joint is formed from the front surface of the connecting portion to the front surfaces of the medial condyle and lateral condyle, and the patella moves relative to the sliding surface in an arch shape from above to below to the lateral medial side, The above shifted state is adapted to the same patella movement.

As a result of the above measures, during the flexion movement of the knee joint prosthesis, the patella moves from the lateral upper part to the medial lower part in an arch shape.
The sliding movement into the joint space can be performed in the same way as the real one. The reason for this is that the medial condyle has a larger distance from the axial plane of the fixation rod than the lateral condyle, and there is a gap between the connecting part connecting both condyles and the connecting surface formed by the anterior surfaces of both condyles. This is because the patella part enters into the above-mentioned joint space. thus,
The knee joint prosthesis of this invention can perform movements similar to those of the patella in a real knee joint.

Hereinafter, this invention will be explained in detail with reference to embodiments shown in the accompanying drawings.

As in the previously mentioned patent application, the femoral joint of the knee prosthesis has a medial condyle 13b and a lateral condyle 13c that slide on the tibia (not shown), with both condyles 13
b, 13c are connected by a flat connecting portion 14 on the top surface. The above medial condyle and lateral condyle 13b, 1
The facing surface of 3c has a guide groove 15 that opens upward at one end, and the guide groove is adapted to engage with a guide shaft (not shown) of the tibia, as disclosed in the above-mentioned patent application. The configuration is similar to that of .

The anterior portion of the connecting portion 14 and the anterior portions of the medial and lateral condyles 13b, 13c form a sliding surface for the patella (not shown).

In order to make the motion of the artificial patella similar to the motion of the real patella, which is performed from the upper lateral side in an arched downward medial direction, the axis of the fixing rod (or fixing shaft) 6 that engages with the femur is provided at the medial condyle and the lateral condyle. It is disposed at a vertical plane 18 slightly shifted toward the lateral condyle 13c from a central plane 17 that extends vertically from the front to the rear of the joint space 16. Thus, the medial condyle 13b is closer to the axial plane 1 than the lateral condyle 13c.
8, the connecting portion 14
the anterior surface and both condyles of the medial and lateral condyles 13
The patella located on the anterior surface of portions b and 13c can enter into the joint space 1 from the upper outer side toward the lower inner side in an arched manner. The patella is thus guided into the joint space 16 and can perform movements that are essentially similar to those of a real patella, while excessive tensioning of the patella band and the resulting wear can be avoided.

[Brief explanation of the drawing]

Figure 1 is a side view of the femoral joint in the left leg artificial knee joint, Figure 2 is a top view of Figure 1, Figure 3 is a view from the Y direction of Figure 1, and Figure 4 is the 2nd view of the femoral joint. figure or third
A cross-sectional view taken along line 18 in the figure, Figure 5 is the X of Figure 1.
It is a figure seen from the direction. 6... Fixed rod, 13b... Medial condyle, 13c
... Lateral condyle, 14 ... Connection part, 15 ... Guide groove,
16... joint space, 17... central plane, 18... vertical plane.

Claims (1)

[Claims for Utility Model Registration] An artificial knee joint prosthesis having an artificial femoral part, which is formed to be able to slide on the upper part of a human tibia, and which has a joint space 16 between them. forming a medial condyle 13b and a lateral condyle 13c, said condyle members 13b, 13c forming a bridge-like connection with a fixation rod 6 extending approximately vertically to connect said knee prosthesis to the human femur; The connecting part 14 is formed with a front surface forming a sliding surface for a prosthetic patella similar to the sliding surface of a human knee joint, and the fixing rod 6 is connected to the medial and lateral condyles. The artificial knee joint prosthesis is arranged in a vertical plane 18 including a position away from a central plane 17 extending in the longitudinal and vertical direction of the joint space 16 provided between the condyles in the direction of the lateral condyle 13c.