JPH0628677B2 - Knee joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an artificial knee joint, in particular, a joint that allows rotational movement.

[Conventional technology]

As a conventional artificial knee joint, the one in which a fulcrum pin is used in order for a femoral fixing member and a tibial fixing member connected by a pair of hinge mechanisms to mutually perform flexion and extension movements is predominant.

However, such a hinge-type joint does not hinder the prescribed flexion-extension movement, but in the joint function of the human body, not only simple flexion-extension movement, but also flexion with rotation between the femur and tibia. Since extension movements are performed, there is a demand for something close to a natural joint that is configured to be able to perform rotation movements in conjunction with flexion extension movements. As an artificial knee joint that meets such demands, for example, Jitsukai Sho 51-984
99, Japanese Patent Publication 58-34138, etc. have already been proposed.

[Problems of conventional technology]

However, in the former one, the full load is received by the fulcrum pin,
Further, the leg inserted into the metal fitting fixed to the tibia is configured to rotate, and the central axis of the rotational movement of the leg does not coincide with the central axis of the fulcrum pin that performs flexion and extension movement. Therefore, concentrated stress always acts on the root of the leg due to the load applied from the central axis of the fulcrum pin to the central axis of rotation. There have been some reports of breakage accidents at the roots of the legs resulting from this. Also, the legs can be freely rotated,
Inserted in the medullary cavity of the tibia, for the metal fitting fixed by cement, the above-mentioned concentrated stress is multiplied by the rotational moment associated with the turning force, resulting in loosening of the cement fixed part,
There is a drawback that the support part of the artificial joint is damaged.

[Means for solving problems]

In order to eliminate the above problems, load is not a fulcrum pin,
The inner cup and the outer cup which are configured to receive the load from the femoral member by the joint member mounted on the tibial fixing member and which receive the fulcrum pin on the protrusion arranged on the pedestal on which the joint member is mounted are rotated. Thus, the tibial fixation member was prevented from being stressed.

〔Example〕

FIG. 1 shows a front sectional view of the artificial knee joint according to the present invention as seen from the front, FIG. 2 also shows a central transverse sectional view thereof, and FIG. The femur fixing member 1 and the tibial fixing member 2 are configured to perform flexion and extension movements as shown by the dashed line in FIG.

The tibial fixing member 2 includes a leg portion 3 to be inserted into a medullary cavity of a tibia, a pedestal 4 on an upper portion of the leg portion 3, and a spherical or cylindrical projection at a substantially central portion of the pedestal 4. 5 is integrally formed with a metal material. Further, an inner cup 6 having a recess 6b for receiving the projection 5 and a shaft hole 6a penetrating in the lateral direction is crowned so that the projection 5 serves as a turning branch shaft. In addition, the inner cup 6 has a shaft hole 7a which is a through hole.
The outer cup 7 with is attached. Further, the joint member 8 is crowned so as to cover the outer cup 7 which has thus received the inner cup 6 inside. In this case, the shaft hole 8a formed in the protruding portion 8b formed on the joint member 8 is
Shaft holes of the inner cup 6 and outer cup 7 built in
After 6a and 7a are arranged so as to communicate with each other coaxially, the projecting portion 8b of the joint member 8 is attached to the femoral fixation member 1 so that its axis is aligned with the screw hole 1a formed in the femoral fixation member 1. It is inserted into the formed concave cavity 1b. After that, the fulcrum pin 9 is screwed into the artificial knee joint as shown in FIGS. 1 and 2.

In the artificial knee joint configured as described above, as shown by the dashed-dotted line in FIG. 2, a rotation angle θ ₁ (maximum about 160 °) between the femoral fixing member 1 and the tibial fixing member 2 about the fulcrum pin 9.
Flexion and extension in any range), and the load is such that the bottom surface 1c of the femoral fixation member 1 has the joint member 8
By slidingly contacting the upper surface of the brim 8c, the bending motion of the knee of the human body can be performed.

At the same time, the inner cup 6 received through the outer cup 7 in the protruding portion 8b of the joint member 8 into which the fulcrum pin 9 is inserted is rotated around the protrusion 5 formed on the pedestal 4 to fix the femur. The member 1 and the tibial fixing member 2 can perform rotational movements with respect to each other at an angle θ ₂ (which can be up to about 40 degrees).

It is desirable that at least the inner cup 6, the joint member 8 and the like among the above-mentioned joint constituent members are made of synthetic resin such as high density polyethylene.

〔The invention's effect〕

As described above, according to the artificial knee joint of the present invention, the femoral fixing member and the tibial fixing member rotate and extend around the fulcrum pin, and at the same time, the protrusion provided on the tibial fixing member is rotated. By doing so, it is possible to bring joint motion closer to that of a natural knee joint in the human body, and it is possible to bring light to joint replacement persons caused by rheumatism, bone cancer, disaster accidents, and the like.

[Brief description of drawings]

1 and 2 are a front sectional view and a central transverse sectional view, respectively, of an artificial knee joint according to the present invention. FIG. 3 is an exploded perspective view of the artificial knee joint according to the present invention. 1: Femur fixing member 2: Tibia fixing member 4: Cradle, 5: Protrusion, 6: Inner cup 7, Outer cup, 8: Joint member 9: Support pin

Claims (1)

[Claims] 1. A projection formed on an upper surface of a pedestal of the tibial fixing member so that the femoral fixing member fixed to the femur and the tibial fixing member fixing to the tibia relatively perform flexion and extension movements. An inner cup is rotatably attached to the inner cup, an outer cup is crowned so as to surround the inner cup, and the brim of a joint member integrally formed with a protrusion that receives the outer cup and the brim is seated on the pedestal. The inner cup, the outer cup, and the protrusion of the joint member in which the axial holes formed in the joint member are aligned with each other are inserted into the concave cavity formed in the femoral fixation member, and the protrusion is opened in the femoral fixation member. Artificial knee joint formed by inserting a fulcrum pin into the shaft hole of the joint member through the screw hole.