JP2722071B2 - Artificial knee joint - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an artificial knee joint having a hinge mechanism.

[Prior art and its problems] Conventional hinged artificial knee joints are disclosed in, for example,
No. 34138, etc., the femoral component and the tibial component are rotatably connected by fulcrum pins, and the overall structure is relatively simple. Since the femoral component is attached to the femur and the tibial component is attached to the tibia at the time of knee replacement surgery, it is difficult to perform the operation efficiently because it is connected and assembled with the fulcrum pin in advance. .

On the other hand, in the case where the femoral component and the tibia component are separated, the workability of mounting and fixing each component to the femur and the tibia is rich, however, thereafter, both components are rotated with the fulcrum pins. They need to be connected freely. Therefore, in order to complete the operation as soon as possible, a structure is generally adopted in which the fulcrum pin can be easily inserted into a predetermined hole.

However, there is a disadvantage that the fulcrum pin is easily inserted and connected and fixed, but has a drawback that the fulcrum can easily be pulled out or fall off. Since there was a risk that the pin would come off and the joint function might be lost, to prevent the pin from coming off,
As disclosed in No. 2943, an annular groove is provided on the inner periphery of the opening of the screw hole of the fulcrum pin, the engagement flange is loosened in this annular groove, and the end face of the fulcrum pin is provided with a protruding portion on the inner side A method has been proposed in which the opening is fitted with a stopper to prevent the fulcrum pin from coming off.However, when a strong rotational torque acts on the fulcrum pin during bending or extension, the fulcrum pin comes off. There was a risk of getting it.

In addition, if the femoral fixation member and the stem member to be inserted and fixed to the femur are integrated, a product tailored to the size of the tumor that occurs in the femur and the size of the spinal cord of the femur can be adjusted according to the case. To prepare, many variations of products are required, and there is a drawback that the number of manufactures and inventories becomes excessive.Therefore, several types of separated femoral fixation members and stem members must be prepared. Although the method of assembling with a fastening bolt is adopted depending on the case, there is a disadvantage that the fastening bolt is loosened and the femur fixing member and the stem member are disassembled.

[Means for solving the problem]

In view of the above problems, the fulcrum pin and the fastening bolt have a slit portion that can be freely opened with a screw hole at a tip end thereof so that the connection pin does not come off once connected, and this is screwed and loosened with a lock bolt having a tapered portion. It is characterized by preventing.

〔Example〕

FIG. 1 is a front view of a fractured main part of an artificial knee joint according to an embodiment of the present invention. Reference numeral 1 denotes a femoral member. This femoral member 1 has a pair of bifurcated legs 1a. A recess 1 is formed between the legs 1a, and a pin hole 1c is formed.

Numeral 2 denotes a tibial member, and a projection 2a having an articulating surface with which the tip surface of the leg 1a slides in contact with the protrusion 2a rotatably inserted into the recess 1b is integrally formed at the upper part. Pin hole 2c
Are provided in the horizontal axis direction.

The protruding portion 2a of the femoral member 1 and the tibial member 2 has a concave portion 1b.
The locking bolt 4 is screwed into the thread groove 3d as shown in FIG. 2 in a state where the pin holes 1c, 1d and 2c formed in the fixing members 1 and 2 respectively correspond to each other. The fulcrum pin 3 is inserted, screwed with a screw groove 3a, and a lock bolt 4 is screwed into the screw groove 3d using a through hole 1d provided in the leg 1a, thereby forming the lock bolt 4. Tapered part
4a is fitted into the thread groove 3d like a taper fitting, and the tip 3b of the fulcrum pin 3 is expanded because the slit 3c is provided so that it can be freely opened, and the pin hole 1c is firmly contacted and fastened. I can do it. In addition, pin hole 1c and fulcrum pin 3
Even if there is a large gap in the manufacturing process, the tip 3b of the fulcrum pin 3 can be greatly expanded by the tapered portion 4a of the lock bolt 4, so that a sufficient coupling force can be obtained. An annular groove 1e is formed on the inner periphery of the opening of the screw hole for the fulcrum pin.
And the plug 5 having an engagement flange 5a in the annular groove 1e and a projection 5b inside the end surface of the fulcrum pin 3 against which the end face of the fulcrum pin 3 is affixed. If this is the case, the engagement action will be more reliable.

Further, the above method can also be used for preventing the screw from being loosened when the femoral member 1 and the stem member 6 are engaged. That is, the fastening bolt 8 in which the lock bolt 7 as shown in FIG. 3 is screwed into the screw groove 8a is screwed into the screw groove 6a of the stem member 6 and fastened. Further, by using a through hole 1f provided in the femoral member 1 and screwing the lock bolt 7, the tip of the thread groove 8a of the fastening bolt 8 is expanded by the tapered portion 7a, and the slit 8c which can be further opened is formed. Due to the formation, the distal end portion 8b of the fastening bolt 8 is expanded, the fastening bolt 8 can be firmly tightened, and the screw can be prevented from coming off without being loosened.

〔The invention's effect〕

As described above, according to the present invention, the femoral member and the tibia member can sufficiently fasten the fulcrum pin that is connected to bendable and extendable. And stable joint function can be maintained. In addition, replacement surgery is easy and can provide a highly reliable artificial knee joint, which greatly contributes to the social welfare of mankind.

[Brief description of the drawings]

FIG. 1 is a front view showing a fractured main part of an artificial knee joint according to an embodiment of the present invention, FIG. 2 is a sectional view showing a fulcrum pin and a lock bolt according to the present invention, and FIG. 3 is a fastening bolt according to the present invention. FIG. 4 is a cutaway view showing a state in which a lock bolt is screwed into. 1: Femur fixation member 2: Tibial fixation member 3: Support pin 4, 7: Lock bolt 5: Plug 6: Stem member 8: Fastening bolt

Claims (1)

(57) [Claims] (1) The femoral fixing member and the tibial fixing member are bent and
In an artificial knee joint in which a hinge member is connected by a fulcrum pin so as to perform an extension motion and a stem member to be inserted and fixed to the femur is fixed to the femur fixing member by a fastening bolt, the fulcrum pin and the fastening bolt An artificial knee joint characterized in that a screw hole having a slit portion that can be freely opened is formed at each end portion, and a lock bolt having a tapered portion is screwed into the screw hole to prevent loosening.