JP3667909B2 - Knee prosthesis - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a knee joint that is highly deformed due to rheumatoid arthritis, knee osteoarthritis, or the like, or an artificial knee joint that is used to restore a joint that has been destroyed due to a traffic accident, disaster, or the like to a normal function. .
[0002]
[Prior art]
Conventionally, the femur member and the tibia are cut by cutting the distal part and proximal part of the femur of the knee joint, which have been destroyed by a disease or accident, and by cutting the distal part of the femur and the proximal part of the tibia. Artificial knee joint replacement is performed to insert and fix each member. The hinge-type one in which both members are rotatably locked by a common pin member, and the femoral member on the sliding surface of the tibial member A surface-sliding type or the like having such a structure that can be bent by rotating is used.
[0003]
[Prior art issues]
However, the above prior art has the following problems.
[0004]
That is, the hinge-type artificial knee joint has a small range of motion because the rotation fulcrum is fixed, and it is inconvenient because it does not reproduce normal human joint motion. In contrast, the surface sliding type reproduces more normal joint motion, but the sliding surface on the femur side is made of metal and the sliding surface of the other tibial member is made higher. Because it was composed of high-density polyethylene, there was a problem in sliding characteristics, and high-density polyethylene wear powder accumulated over time, causing adverse effects such as causing foreign body reactions in living cells. was there.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems of the prior art, an artificial knee joint of the present invention is an artificial knee joint comprising a femoral member fixed to a femur and a tibial member fixed to a tibia and having a sliding surface made of a ceramic material. The main convex sliding surface having a spherical shape is formed on the left and right sides of the back base side of the femoral member, and the main concave sliding surface having a spherical shape is formed on the left and right sides of the other tibial member. The convex and concave main sliding surfaces are fitted and rotated with each other, and a spherical sub-convex sliding surface is formed at the rear central sliding portion of the femoral member, and the other tibial member is formed. A spherical concave sub-sliding surface is formed in the rear center sliding part, and when bent, these convex and concave sub-sliding surfaces are configured to fit and rotate with each other, and The roundness of the convex and concave main sliding surfaces and the convex and concave secondary sliding surfaces is within ± 1 μm. Further, the clearance between the main convex sliding surface and the main concave sliding surface and the clearance between the sub convex sliding surface and the sub concave sliding surface are set to 7 to 10 μm or less.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a ceramic femoral member 1 constituting an artificial knee joint according to the present invention. The femoral member 1 has spherical main convex sliding surfaces 2 and 2 formed on the left and right back bottom sides, and a spherical secondary convex sliding surface 3 on the rear central sliding portion. Is formed. Of the front side surface 12 in contact with the bone of the femoral member 1, the porous portion 13 formed by agglomerating and fixing ceramic small particles on the anterior condyle wall region and the like and surface-coated with the calcium phosphate material is formed to proliferate the bone. By inducing invasion, the fixing force with the bone may be reinforced, or a pair of spikes 14 and 14 may be formed on the bottom surface part to prevent rocking and dropping.
[0007]
Next, FIG. 2 shows a perspective view of the tibial member 4 constituting the knee joint together with the femoral member 1, and FIG. 3 shows a cross-sectional view taken along the line AA of FIG. Spherical main concave sliding surfaces 5 and 5 are formed, and a spherical secondary concave sliding surface 6 is formed on the rear central sliding portion. The sliding surfaces 5 and 6 of the tibial member 4 are made of ceramic for sliding with the femoral member 1, and further, the inner bottom surface 8 of the metal tray 7 that holds the sliding surfaces 5 and 6. An intermediate member 9 made of synthetic resin such as high-density polyethylene is inserted between the sliding surfaces 5 and 6 for shock buffering. A stem 15 that is inserted into the tibia bone marrow cavity is formed integrally with the tray 7 below the tray 7.
[0008]
FIG. 4 shows a state in which the femoral member 1 and the tibial member 4 are respectively attached to the femur 10 and the tibia 11 and are in the extended position. In this state, the femoral member 1 having the same spherical radius as the ultra-high circularity. The main convex sliding surfaces 2 and 2 and the main concave sliding surfaces 5 and 5 of the tibial member 4 slide smoothly. Further, when bent from this extended position, the secondary convex sliding surface 3 of the femoral member 1 is fitted into the secondary concave sliding surface 6 of the tibial member 4 as shown in FIGS. Because it is housed, it can be bent at the rear of the tibial member 4 without moving forward, and the range of motion can be improved up to a movable angle of 135 ° or more that can be seated straight. The sub-convex sliding surface 3 of the femoral member 1 and the sub-concave sliding surface 6 of the tibial member 4 slide smoothly.
[0009]
Generally speaking, the problem with sliding surfaces made of high-density polyethylene or metal is that the sliding characteristics are not excellent, and wear powder is likely to be generated. The substance may be adversely affected. On the other hand, the artificial knee joint of the present embodiment configured as described above includes the sliding surfaces 2, 3, 5, and 6 of the femoral member 1 and the tibial member 4 made of a ceramic material having excellent sliding characteristics. In addition, not only that, the main convex sliding surface 2 of the femoral member 1 and the main concave sliding surface 5 of the tibial member 4 have the same spherical radius as the ultrahigh roundness, By configuring the sub-convex sliding surface 3 of the femoral member 1 and the sub-concave sliding surface 6 of the tibial member 4 to have the same high radius and the same spherical radius, ideal sliding characteristics can be obtained. There is almost no abrasion powder.
[0010]
As the ceramic material constituting the sliding surface 6 of the femoral member 1 and the tibial member 4 as described above, a high-strength material such as alumina, zirconia, silicon carbide, or silicon nitride is used. Of these, alumina is slidable. In particular. The sliding surface made of such a material should be as smooth as possible, but it is preferable that at least the average surface roughness Ra ≦ 0.02 μm. When the average surface roughness Ra is larger than 0.02 μm, the slidability is lowered and the ceramic particles may be easily dropped from the surface. Also, the spherical deviation of each of the main convex sliding surfaces 2, 2, main concave sliding surfaces 5, 5, sub convex sliding surface 3, and sub concave sliding surface 6 is ± 1 μm. The clearance between the main convex sliding surfaces 2 and 2 and the main concave sliding surfaces 5 and 5 and the sub convex sliding surface 3 and the sub concave sliding surface 6 is preferably 7 to 10 μm or less. This is because if the value is outside these numerical ranges, the sliding characteristics are deteriorated, and the ceramic particles may easily fall off from the surface. Further, as the spherical radius R ₁ (see FIG. 4) of the main convex sliding surfaces 2 and 2 and the main concave sliding surfaces 5 and 5, R ₁ = 10 to 20 mm, and the sub convex sliding surface 3 The spherical radius R ₂ (see FIG. 5) of the sub-concave sliding surface 6 is preferably in the range of R ₂ = 5 to 15 mm. If the value is outside these numerical ranges, the movement of the artificial knee joint does not appropriately follow the movement of the human body, which may cause dislocation of the member.
[0011]
In addition, the tray 7 and the stem 15 of the tibial member 4 are not only made of metal such as stainless steel, cobalt-chromium alloy, titanium, titanium alloy, but also carbon fiber, synthetic resin, or carbon fiber. Further, the contact surface of these materials with the bone may be coated with alumina, apatite, titanium oxide, titanium nitride or the like.
[0012]
As mentioned above, although embodiment of this invention was described in detail, it cannot be overemphasized that this invention is not limited to this embodiment, and can be made into arbitrary forms, unless it deviates from the objective of invention.
[0013]
【The invention's effect】
As described above, the knee prosthesis of the present invention has a sliding surface made of a high-strength ceramic material, and further, a main convex sliding surface having a spherical shape on the left and right sides of the back base of the femoral member. And a spherical main concave sliding surface is formed on the left and right sides of the other tibial member. During extension, the convex and concave sliding surfaces are fitted and rotated, and the femur A spherical secondary convex sliding surface is formed on the rear central sliding portion of the member, and a spherical secondary concave sliding surface is formed on the rear central sliding portion of the other tibial member. Sliding surfaces with convex and concave sliding surfaces that fit and rotate, that is, slides with convex and concave sliding surfaces made of ceramic and spherical, both during extension and bending. Excellent wear resistance. In particular, the roundness of the convex, concave main sliding surface and the convex, concave secondary sliding surface is within ± 1 μm, and the clearance between the main convex sliding surface and the main concave sliding surface And the clearance between the sub-convex sliding surface and the sub-concave sliding surface is 7 to 10 μm or less, and an ideal sliding characteristic is obtained by having a structure having the same radius as the ultra-high roundness, Little wear powder is generated.
[Brief description of the drawings]
FIG. 1 is a perspective view of a femoral member constituting an artificial knee joint of the present invention.
FIG. 2 is a perspective view of a tibial member constituting the artificial knee joint of the present invention.
FIG. 3 is a cross-sectional view taken along line AA in FIG.
FIG. 4 is a cross-sectional view of a principal part showing a state in which the artificial knee joint of the present invention is attached to the femur and tibia and extended.
FIG. 5 is a cross-sectional view of a principal part showing a state in which the artificial knee joint of the present invention is attached to the femur and tibia and bent.
FIG. 6 is a cross-sectional view of a principal part showing a state in which the artificial knee joint of the present invention is attached to the femur and tibia and bent.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Femoral member 2 Main convex sliding surface 3 Sub convex sliding surface 4 Tibial member 5 Main concave sliding surface 6 Sub concave sliding surface 7 Tray 8 Inner bottom surface 9 Intermediate member 10 Femur 11 Tibial 12 Front side surface 13 Porous part 14 Spike 15 Stem R ₁ , R ₂ sphere radius

Claims (3)

In a prosthetic knee joint comprising a femoral member fixed to the femur and a tibial member fixed to the tibia and having a sliding surface made of a ceramic material, a spherical main convex on the back base side of the femoral member A spherical main concave sliding surface is formed on the left and right sides of the other tibial member, and these convex and concave main sliding surfaces are fitted to each other and rotate when extended. And a spherically shaped secondary convex sliding surface is formed on the rear central sliding portion of the femoral member, and a spherical secondary concave sliding surface is formed on the rear central sliding portion of the other tibial member. When formed and bent, the convex and concave sub-sliding surfaces are configured to fit and rotate with each other , and the convex and concave main sliding surfaces and the convex and concave sub-sliding surfaces. The roundness of the surface is within ± 1 μm, and the clearance between the main convex sliding surface and the main concave sliding surface The artificial knee joint is characterized in that a clearance between the sub-convex sliding surface and the sub-concave sliding surface is 7 to 10 μm or less . The convex and concave main sliding surfaces and the convex and concave secondary sliding surfaces have an average surface roughness Ra ≦ 0.02 μm. m The artificial knee joint according to claim 1, wherein: Spherical radius R of the main convex sliding surface and the main concave sliding surface ₁ 10 to 20 mm, the spherical radius R of the sub-convex sliding surface and the sub-concave sliding surface ₂ The artificial knee joint according to claim 1, wherein is 5 to 15 mm.

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