JPH06339491A - Artificial knee joint - Google Patents

Abstract

(57) [Summary] [Structure] A convex projection and / or a concave groove having a height or depth of 2 mm or more and a length of 5 mm or more is formed in a substantially vertical direction on the inner surface of the anterior wall and / or posterior wall of the femoral side member. Formed. [Effect] Femoral side member on the femur, without using cement,
Since the bone can be easily and firmly fixed and the wall thickness can be reduced, the bone cutting amount can be minimized. Therefore, it is safe for the living body,
An artificial knee joint that can be used for a longer period of time can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial knee joint, which replaces a knee joint having a significantly reduced or impaired function due to a disease such as osteoarthritis.

[0002]

2. Description of the Related Art In a total knee arthroplasty, in order to firmly fix the femoral member to the femur, the bones on the inner surfaces of the anterior wall and the posterior wall and on the joint surface of the distal part of the femur contacting the inner surfaces It is necessary to accurately perform the cut surface so as to obtain an appropriate press fit margin with the bone so that an appropriate press input can be obtained when the femoral side member is driven into the distal part of the femur. It was

However, the actual bone cutting accuracy is not sufficient to meet this requirement, and it is unavoidable that there will be some misalignment between surfaces and the formation of gaps. For example, the bone cutting angle is 5
If it is °, the angle will be 1 ° for normal bone cutting instruments.
A variation of about 2 ° occurs. Therefore, there is a gap between the bone and the femoral side member, so that the femoral member cannot be firmly fixed, or conversely, there are too many press-fitting margins. The bone in the vicinity of the contact surface with the member is excessively compressed, resulting in biased stress transmission, which may result in so-called stress shield, which may cause bone resorption. If the femoral member is made of a metal material, even in such a case, the anterior wall and the posterior wall are relatively easily elastically deformed, so that the displacement due to the bone cutting may occur to some extent in the initial stage after fixation. It can be absorbed, but when the femoral member is made of a brittle material such as ceramics, the fixation force with the femur must depend on the accuracy of the osteotomy, which is not accurate. In some cases I was forced to use bone cement. Accuracy in such osteotomy was a big problem.

As a conventional artificial knee joint designed for the purpose of solving such a problem, Japanese Patent Laid-Open No. 63-279838.
As proposed in Japanese Patent Publication No. JP-A-2003-264, the femoral side member is configured to fit so as to sandwich the distal portion of the femur between the inner surfaces of the front wall and the rear wall thereof, and to contact the distal end surface of the femur. There has been an artificial knee joint in which a nail is formed on the inner surface of a sliding portion in contact with the sliding portion and the nail is fixed to the femur without using bone cement by press-fitting the nail into the femur. In addition, JP-A-64-68255
As proposed in Japanese Patent Publication, instead of the nail, a plate-shaped fin is formed on the inner surface of the sliding portion, and the plate-shaped fin is configured to be press-fitted into the femur and the front wall and There was an artificial knee joint including a femoral-side member, which was formed on the inner surface of the posterior wall to form a plurality of tooth-shaped projections having a sawtooth shape with a height of about 1 mm and which was devised so as to enhance the fixing force to the femur.

[0005]

However, in the above-mentioned conventional artificial knee joint, a nail or a plate-like projection provided on the inner surface of the sliding portion of the femoral side member is driven into the soft and weak cancellous bone of the femur. Since they are designed to be fixed, the fixing force to the femur obtained by these is only a supplementary degree, and even if initial fixation is obtained, it is necessary for long-term fixation in the body. It did not meet the dynamic conditions.

Further, considering the principle of the replacement technique of keeping the bone cutting amount to a minimum, the bone cutting for fitting the protrusion located at the approximate center of the distal end face of the femur is originally It was an extra bone cut, which was not desirable.

[0007]

It is an object of the present invention to increase the force of fixing the femoral side member constituting the artificial knee joint to the femur and to reduce the wall thickness thereof, but the femoral bone can be cut a little. To provide an artificial knee joint.

[0008]

[Means for Solving the Problems] To solve the above problems,
The artificial knee joint of the present invention has a height or depth of 2 mm or more in a substantially vertical direction on the inner surface of the anterior wall and / or the posterior wall of the femoral side member,
A convex protrusion and / or a concave groove having a length of 5 mm or more was formed.

[0009]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view of an artificial knee joint A as an example of the present invention, 20 is a tibial member that replaces the distal portion of the tibia, and 1 is a femoral member that replaces the distal portion of the femur. .

The upper side of the tibial member 20 is the femoral member 1 above.
Is a sliding surface portion 21 on which the sliding portion 4 located on the lower side slides, and a rod-shaped stem 22 is formed on the lower side to be inserted into the tibial bone marrow cavity. .

The other femur member 1 is composed of a plate-shaped front wall 2, two left and right rear walls 3, 3 and a sliding portion 4 which connects these and has a substantially arc shape.

The outer surfaces of the anterior wall 2, the sliding portion 4 and the posterior wall 3 of the femoral member 1 have smooth curved surfaces which are similar to the joint sliding surfaces of the femur to be replaced in the normal state. An intercondylar part 5 that divides the two posterior walls 3 and a part of the sliding part 4 at the center is formed at a position that interferes with the attachment part of the anterior and posterior cruciate ligaments located posterior to the femur.

The inner surface 2a of the front wall is a flat surface, and in the substantially vertical direction of the center thereof, there is a pressure-contacting front projection 6 having a hemispherical horizontal cross section and a columnar shape as a projection protruding into the bone. Further, two pre-pressing grooves 7 having a hemispherical horizontal section are formed in parallel with the pre-pressing projections 6 on the left and right of the pre-pressing projections 6 as concave grooves for fitting a part of bone. is doing.

Further, the inner surfaces 3a, 3a of the rear wall are flat surfaces, and in the substantially vertical direction of the center thereof, as a convex projection fitted in the bone, a columnar shape having a hemispherical horizontal cross section is formed. Protrusions 8 and 8 are formed.

The pre-pressing projection 6 and the pre-pressing groove 7 have a length of 20 mm and a horizontal cross-section radius of 5 mm, and the post-pressing projection 8 has a size of 15 mm.
The radius of the horizontal cross section is 5 mm, at least 1-2 mm
It is designed to secure a press-fitting margin.

In the artificial knee joint A of the present invention thus constructed, the femoral member 1 is provided with the front wall inner surface 2a and the rear wall inner surface 3a.
The convex projections (pre-pressing contact 6, post-pressing projections 8 and 8) and concave grooves (pre-pressing grooves 7 and 7) formed on 3a contact the bone with a sufficiently large press-fitting margin and a large area as described above. Since it is configured to be in contact with each other, the femoral member 1 is firmly fitted and fixed to the bone at this portion. Thereby, the femoral member 1
The internal stress is generated more in the surroundings of the convex protrusion and the concave groove, particularly in the convex protrusion, and the stress is reduced in other portions by that much, so that it is a cross-sectional view taken along the line X-X in FIG. 2. In FIG. 3, which is a cross-sectional view taken along the line YY of FIG. 1, the cross-sectional shape of the conventional femur side member 1 ′ is shown in contrast with the two-dot chain line, the strength of the front wall 2 and the rear wall 2 The wall thickness of the walls 3 is 1
It can be reduced by about 2 mm, and the amount of bone cutting can be reduced accordingly.

The shape of the convex projection 6 and the concave groove 7 formed on the femur side member 1 is not limited to the semi-cylindrical shape, but may be a quadrangular prism shape or a triangular prism shape as shown in FIG. Thighs are good.

Further, in order to firmly fix the femur side member 1 to the femur, it is preferable that the height or depth of the convex protrusion and the concave groove is 2 mm or more and the length is 5 mm or more. On the other hand, when the depth is less than 2 mm or the length is less than 5 mm, even if the initial fixability is obtained, excessive stress is generated in the convex protrusion and the concave groove, and the bone tissue to be contacted is It is not preferable because it may be absorbed.

Next, the bone cutting for replacing the distal portion of the femur by the femoral member 1 constituting the artificial knee joint A of this embodiment will be described. The perspective view of FIG. 5 shows a distal portion F of the femur that has undergone osteotomy for installing the femoral side member 1, and 9 indicates the femur with which the front wall inner surface 2a of the femoral side member 1 abuts. The resection front surface of the distal bone portion F, 10 is a resection end surface that abuts on the sliding portion inner surface 4a of the femur side member 1, and 11 is a resection rear surface that abuts the rear wall inner surface 2a of the femur side member 1.

The cutting front face 9 and the cutting end face 10 and the cutting end face 10 and the cutting back face 11 are at right angles to each other.
That is, the excision front surface 9 and the excision front surface 11 are excised so as to be substantially parallel to each other, and the excision front projections 1 corresponding to these are fitted into the pre-pressing grooves 7, 7 of the femoral member 1.
3, 13 and the convex projections (pre-pressing projection 6, post-pressing projection 8) of the femoral member 1 are fitted to the cutting front surface groove 12 and the post cutting front surface groove 14, 14 at corresponding positions. Is formed.

The vicinity of the center of the resection front face 9 of the distal part F of the femur, that is, the periphery of the pre-resection protrusion 6 is the site where the bone cortex is most likely to remain, and thus the femur of the femoral side member 1 is extended to the femur. The fixing force of is increased.

The cutting front projections 13, 13 are semicircles having a radius of 5 mm in a horizontal cross section, while the cutting front groove 12 and the rear cutting grooves 14, 14 are semicircles having a radius of 4 mm in a horizontal cross section. The anterior projections 13 and 13 have a press-fitting margin of 1 mm with respect to the femoral member 1, and the convex projections (the pre-pressing projection 6 and the post-pressing projection 8) of the femoral member 1 are the pre-cut groove 12 and the post-cut groove 14. , 14 with a press-fitting margin of 1 mm.

The side view of FIG. 6 shows the distal portion F of the femur in a state where an osteotomy is performed to form the anterior resection groove 12 and the resection groove 14, and the distal femur is shown with the tibia T bent. Part F
A gauge 15 that comes into contact with the resection front surface 9, the resection end surface 10, and the post-resection surface 11, which have already been cut, is attached to the
The drill D is made to act from the drill guide hole 16 provided so as to stand upright in the groove 5, and semicircular grooves, that is, the cut front surface groove 12 and the cut back surface groove 14 are formed at predetermined positions.

According to this method, the drill guide hole 1
Since the bone is cut by the drill D guided to 6,
The cut front surface groove 12 and the cut back surface groove 14 can be formed with an accuracy within about 0 micron. Therefore, the convex projections of the femoral member 1 (the pre-press-fit projection 6 and the post-press-fit projection 8,
8) and the concave groove (grooves 7 and 7 before press fitting) and the bone,
Since it fits tightly with a press-fitting margin of about 1 mm, even a technically inexperienced operator can fix the femoral side member 1 to the femur with sufficient fixing force without using bone cement. .

The total number of convex protrusions and / or concave protrusions is preferably 2-10. On the other hand, it is not possible to obtain a sufficient fixing force within the femoral member 1 having only one convex and / or concave projection, and if it is 10 or more, the required bone cutting amount becomes too large. Not preferable.

The convex projections and / or concave projections do not necessarily have to be formed on both the front wall inner surface 2a and the rear wall inner surface 3a, but may be formed only on the front wall inner surface 2a or the rear wall inner surface 3a. Is also good.

[0027]

As described above, in the artificial knee joint of the present invention, the height or depth of 2 mm or more and the length of 5 mm or more are convex in a direction substantially perpendicular to the inner surface of the anterior wall and / or posterior wall of the femoral side member. By forming the protrusions and / or the concave grooves, the femoral side member can be easily and firmly fixed to the femur without using cement, and the thickness of the member can be reduced. The amount of cutting can be minimized. Therefore, it is possible to provide an artificial knee joint that is safe for the living body and can be used for a longer period of time.

[Brief description of drawings]

FIG. 1 is a perspective view of an artificial knee joint according to the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a sectional view taken along line YY of FIG.

FIG. 4 is a sectional view taken along line XX of FIG.

FIG. 5 is a perspective view of a distal femur.

FIG. 6 is a side view of the distal femur.

[Explanation of symbols]

 A: Artificial knee joint D: Drill F: Femoral distal part 1: Femoral side member 2: Anterior wall 2a: Front wall inner surface 3: Rear wall 4: Sliding part 4a: Sliding part inner surface 5: Intercondylar part 6: Pre-pressing protrusion 7: Pre-pressing groove 8: Post-pressing protrusion 9: Resection front face 10: Resection end face 11: Resection front face 12: Resection front face groove 13: Resection front protrusion 14: Resection front face protrusion 15: Gauge 16: Dolly guide hole 20 : Tibial member 21: Sliding surface part 22: Stem

Claims (1)

[Claims] 1. A tibial member that replaces the distal portion of the tibia, an anterior wall that replaces the anterior surface of the joint surface of the distal femur, and inner and outer condyle sides of the posterior surface of the distal joint of the femur. A femoral side member consisting of a substantially arcuate sliding portion, which functions as a main joint surface connecting the front wall and the rear wall with each other,
An artificial knee joint comprising a femoral side member formed with a convex protrusion and / or a concave groove having a height or depth of 2 mm or more and a length of 5 mm or more in a substantially vertical direction on the inner surface of the anterior wall and / or the posterior wall. .