JPH0592018A - Artificial joint - Google Patents

Abstract

PURPOSE:To obtain the artificial joint with which the generation of worn powder is prevented to improve safety by optimizing the modulus of elasticity of a stem part to assure the secure fixing into a vital implantation part. CONSTITUTION:The artificial joint 1 is constituted of a head part 2, a neck part 3 and the stem part 4. The head part 2 is a member having a curved surface and is connected freely turnably by being fitted into the recessed part of a cup. Metals, alloys or ceramics having excellent corrosion resistance as hard materials having excellent wear resistance are used as the constituting material. The neck part 3 is formed of the assemblage of metallic fibers 7 of 0.01 to 2.0mm diameter in the form of a woven fabric, knitted fabric or net-like material. Metals, such as stainless steels and titanium alloys, having excellent corrosion resistant are used as these fibers. Above all, a shape memory alloy is more preferable. The stem part 4 is formed by implanting the assemblage of the metallic fibers 7 extended from the neck part 3 toward the front end 6 of the stem into a resin material 8 for vital body. The stem part is so molded as to coincide with the shape of the medullary cavity inserted into the stem part. The artificial joint which can be securely, safely and surely implanted and fixed by the balance of the bending modulus of elasticity with the vital bone is thus obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial joint which replaces a bone joint of a living body.

[0002]

2. Description of the Related Art Treatment for replacing the deformation or loss of bone joints in the human body with artificial joints is widely performed in orthopedics and the like. For example, with respect to femoral head necrosis, it is often practiced to remove the necrotic head and then restore the joint function by prosthesis of an artificial joint.

That is, in this treatment, the stem part of an artificial joint having a femoral head and a stem part is embedded and fixed in the medullary cavity of the femur, and a cup (socket) is fixed to the lumbar bone and the concave part of the cup is fixed. The bone heads are fitted and these are rotatably connected.

Such an artificial joint has mechanical strength, elasticity (toughness), durability, in-vivo stability (no corrosion or deterioration with respect to body fluid), and biocompatibility (bone formation promoting action, etc.). Properties such as compatibility with surrounding tissues), safety (no toxicity, degradability, etc.) and processability are required.

However, a material satisfying all of these characteristics has not been found yet, and at present, as a constituent material of an artificial joint, mainly a metal such as stainless steel, cobalt-chromium alloy, titanium, titanium alloy, or the like, Alternatively, ceramics such as alumina are used.

By the way, the bending modulus of elasticity of the artificial joint made of metal is significantly larger than that of the living bone. That is, the bending elastic modulus of human cortical bone is about 16 GPa, and stainless steel (SUS316L) and Co-Cr used for artificial joints are used.
Alloys and Ti-6% Al-4% V alloys have bending elastic moduli of 200, 213 and 124 GPa, respectively, which are 8 to 10% of that of bone.
13 times.

[0007] Further, the artificial joint made of metal is heavy,
There is a drawback that the burden (or feeling of burden) on the patient is large.

A load, especially a repeated load is applied between the artificial joint and the living bone into which the artificial joint is embedded due to, for example, a motion such as weight or walking, but in the case of a metal artificial joint, as described above, the bending elasticity is increased. Because of the high rate, when the load causes bending, twisting, or bending, stress is locally concentrated, and bone may be broken at this concentrated portion.

[0009] Further, although the urging of the bone (bone-forming effect) is observed in the portion where the load is transmitted from the stem portion of the artificial joint to the living bone, the bone is urged to the bone in the portion other than the stress concentration portion where the load is not applied. It has been reported that the bone tissue is resorbed and the bone mass is reduced to loosen the fixation of the artificial joint to the living bone because the irritation is eliminated.

In order to adapt the bending elastic modulus of the artificial joint to that of the living bone, there are a method of thinning the stem portion of the artificial joint, a method of hollowing the stem portion, a method of using a material having a small elastic modulus, and the like.

In the method of making the stem portion thin, the contact area with the bone marrow cavity to be embedded becomes small, and it is difficult to evenly adhere the stem portion to the bone marrow cavity, so that a firm fixation cannot be obtained. There is a drawback.

As a method for hollowing the stem portion, a hollow artificial joint stem is disclosed (Japanese Patent Laid-Open No. 01-148254). However, in the present invention, the elastic modulus is not sufficiently improved, and the hollow internal space of the stem portion is partially opened to communicate with the outside. There is a drawback that a large amount of bleeding blood and other bodily fluids are stored in the space, delaying the healing of the affected area, and causing infection due to bacterial propagation.

As a method of using a material having a small elastic modulus, it has been proposed to manufacture an artificial joint using engineering plastics (US Pat. No. 4902).
297). In this case, the head of the artificial joint is made of the above-mentioned metal or ceramics, which is a material of high hardness, for reasons of wear resistance and friction resistance, and the neck and stem portions following the head are softer than those of metal or the like. It will be composed of engineering plastics.

However, since the bone head and the neck portion have different hardness, when the artificial joint is repeatedly subjected to a load such as walking, a minute vibration causes the neck portion to be worn and abrasion powder of engineering plastics to be generated. .. It has been reported that such abrasion powder activates (proliferates) macrophages and induces arthritis and the like, which is a toxicity to the living body (Orthopedic surgery MOOK, No. 4).
5, Kinbara Publishing).

[0015]

DISCLOSURE OF THE INVENTION An object of the present invention is to make fixation to a living body implantation portion more robust and reliable by optimizing the elastic modulus of a stem portion constituting an artificial joint, and to generate abrasion powder. An object of the present invention is to provide an artificial joint that can prevent the above and improve the safety to the living body.

[0016]

These objects are achieved by the present invention described in (1) to (6) below.

(1) In an artificial joint comprising a head made of a hard material, a neck portion following the head portion, and a stem portion following the head portion, the neck portion is made of a metal containing an aggregate of metal fibers. The artificial joint is characterized in that the stem portion is obtained by embedding the metal fiber aggregate in a biomedical resin material.

(2) The artificial joint according to the above (1), wherein the neck portion is formed by sintering the aggregate of the metal fibers by a powder sintering method.

(3) The artificial joint according to the above (1) or (2), wherein the aggregate of metal fibers is a woven, knitted or net-like material of metal fibers.

(4) The artificial joint according to any one of (1) to (3) above, wherein the metal fiber is composed of a shape memory alloy.

(5) The diameter of the metal fiber is 0.01
The artificial joint according to any one of (1) to (4) above, wherein the artificial joint has a thickness of 2.0 mm.

(6) The biomedical resin material is at least one selected from the group consisting of polyetherketone, polyetheretherketone, polyallyletherketone, polyphenylene sulfide, and polysulfone. (1) to (5) ).

[0023]

DETAILED DESCRIPTION OF THE INVENTION The artificial joint of the present invention will now be described in detail with reference to the preferred embodiments shown in the accompanying drawings.

FIG. 1 is a front view showing a structural example of an artificial joint of the present invention, and FIG. 2 is a sectional view taken along line AA in FIG.
As shown in FIG. 1, an artificial joint (artificial head) 1 has a head 2
And a neck portion 3 following this, and a metal stem portion 4 following this.

The head 2 is a member having a curved surface such as a spherical shape, and the head 2 is fitted into a recess of a cup (socket) not shown, and these are rotatably connected.

A hard material is used as the constituent material of the head 2 because it is excellent in wear resistance. Specifically, for example, stainless steel (for example, SUS316, S
US316L), cobalt-chromium alloy, cobalt-chromium-nickel alloy, titanium, titanium alloy (for example, Ti.
-6% Al-4% V) and other metals, alloys with excellent corrosion resistance,
Alternatively, for example, ceramics such as alumina and zirconia can be used.

The head 2 may be hollow or solid.

The neck portion 3 is made of metal containing an aggregate of metal fibers 7 which will be described later. That is, the metal fiber 7
It is preferable that the aggregate of (1) is sintered, and in particular, it is hardened by a powder sintering method as described later. This is because the powder sintering method has the advantages that the required shape can be freely formed and the materials can be easily compounded.

It is sufficient that the neck portion 3 is finally made of metal, and it is not necessary that the metal fibers 7 remain in their original shape. For example, the metal fibers 7 are welded together. Alternatively, the metal fibers 7 may be in a melted and solidified state. In particular, the metal fibers 7 may not exist near the outer surface of the neck portion 3.

The connection between the neck portion 3 and the head portion 2 is, for example,
It is preferably made by simultaneous sintering, screwing, taper fitting, adhesion or the like.

As described above, since the neck portion 3 is made of metal, even if a load is repeatedly applied to the artificial joint and a slight vibration occurs, at the joint portion (edge portion) with the head portion 2,
No abrasion powder is generated.

When the metallic head 2 is used, the metal forming the neck 3 may be the same as or different from the constituent metal of the head 2.

The stem portion 4 is a portion that is embedded and fixed in the bone marrow cavity, and is preferably formed continuously and integrally with the neck portion 3. The stem portion 4 includes a stem base portion 5 on the neck portion 3 side and a stem tip portion 6.

Since the outer periphery of the stem base 5 and the bone marrow cavity (in particular, the bone marrow cavity enlarged by reaming) are in close contact with each other, the stem base 5 is thicker than the neck portion 3 and the stem tip portion 6. The shape is shaped to match the shape of the bone marrow cavity to be implanted. Also, the stem tip 6
Has a tapered shape because it is inserted deep into the bone marrow cavity.

As shown, the axis of the stem tip 6 is
It is inclined, for example, by about 15 to 35 degrees with respect to the axis of the neck portion 3.

The stem portion 4 is formed by embedding an aggregate of metal fibers (thin metal wires) 7 extending from the neck portion 3 toward the stem tip portion 6 in the biomedical resin material 8. ..

When the stem portion 4 is composed only of a metal material, the bending elastic modulus is remarkably increased, bone destruction and absorption occur as described above, and a substance such as nickel and vanadium which is toxic to the living body. Elution occurs. On the contrary, when the stem portion 4 is made of only the biomedical resin material, the strength (particularly the strength against pulling, bending, and twisting) is insufficient, and the durability is poor. In the present invention, the stem portion 4
Is composed of a composite reinforced fiber resin material obtained by embedding an aggregate of the metal fibers 7 in the biomedical resin material 8, and therefore has the advantages of both the metal material and the biomedical resin material, and Has a suitable strength and elastic modulus, is excellent in durability, and prevents elution of toxic substances.

The metal fiber 7 may be disposed on at least the stem base portion 5 of the stem portion 4. That is, those provided only on the stem base 5, those provided over the entire length of the stem 4, or those provided on the stem base 5 and a part of the stem tip 6 following it. (See FIG. 1).

When implanting and fixing the artificial joint 1 in, for example, the femur, the stem tip 6 is inserted up to the compact part (compact bone), and the stem base 5 above it is located in the cancellous bone part. However, in the cancellous bone, since the bone marrow cavity is enlarged due to reaming, the contact area with the outer periphery of the stem base portion 5 becomes large, and therefore the balance of bending elastic modulus between the artificial joint 1 and the living bone becomes important. .. In order to prevent bone destruction and resorption (particularly bone resorption in the calcar part) due to excessive bending elasticity as seen in the metal stem part, it is above the lesser trochanter when implanting an artificial joint. It is particularly effective to improve the bending elastic modulus of the stem base portion 5.

Further, in the stem portion 4, the metal fiber 7
Is not exposed on the outer surface of the stem portion 4, or
Even if it is exposed, it is preferably small.

The metal fibers 7 may be either short fibers or long fibers, and may be linear or have a bent portion (for example, bulky processed).

The aggregate form of the aggregate of metal fibers 7 is as follows.
It is not particularly limited, and may be a bundle of metal fibers 7, but a woven fabric, a knitted fabric, or a net-like product (mesh) of the metal fibers 7
Is preferred. As a result, the strength, particularly the strength in the axial direction of the stem portion 4 and the direction orthogonal thereto, increases,
In the stem portion 4, the adhesive force with the below-described biomedical resin material is increased, and the stem portion 4 functions more effectively as a metal fiber reinforced resin.

Further, when the aggregate of the metal fibers 7 is a woven, knitted or net-like material of the metal fibers, as shown in FIG. 3, the woven fabric of the metal fibers 7 is formed into a tubular shape, and the tubular body 7 is formed.
It is preferable to arrange a plurality of 1s concentrically. With such an arrangement, the above function is further improved.
In this case, the installation interval between the adjacent tubular bodies 71 is preferably about 0.1 to 2 mm on average. Moreover, the length of each tubular body 71 may be the same or different.

In the neck portion 3 and the stem portion 4, the aggregated form of the metal fibers 7 may be the same or different.

As the constituent material of the metal fiber 7, for example,
Stainless steel (eg SUS316, SUS316
L), cobalt-chromium alloy, cobalt-chromium-nickel alloy, titanium, titanium alloy (for example, Ti-6% Al).
-4% V, Ti-49 to 51% Ni) and other metals having excellent corrosion resistance can be used. Among them, it is particularly preferable to use the shape memory alloy (Ti-49 to 51% Ni). Since this shape memory alloy has excellent followability with respect to repeated loads, resilience, and fatigue characteristics, stability and durability are improved during long-term implantation.

The preferable range of the diameter of the metal fiber 7 depends on the kind of the constituent metal, but is usually 0.01 to 2.0 mm.
Is preferable, and 0.1 to 1.0 mm is more preferable. When the diameter of the metal fiber 7 is less than 0.01 mm, it becomes difficult to mix it with the powder during sintering, and when it exceeds 2.0 mm, the strength as a composite with a resin decreases.

The number of the metal fibers in the aggregate of the metal fibers 7 is not particularly limited, but the metal fibers 7 having the above diameter are used.
In the case of, about 4 million to 100, especially 40,000 to
It is preferable that the number is about 400.

The arrangement density of the metal fibers 7 in the stem portion 4, particularly the stem base portion 5, is not particularly limited, but is about 1,000,000 to 20 fibers / cm ² , and particularly 10000 to 100 fibers / cm ^2.
It is preferably about ² . The arrangement density of the metal fibers 7 may be different between the central portion and the peripheral portion of the stem portion 4.

The biomedical resin material 8 is a resin material which is stable in the body, that is, does not cause decomposition, alteration, deterioration, etc., and does not generate harmful eluate. For example, polyetherketone, Examples thereof include ketone resins such as polyether ether ketone and polyallyl ether ketone, and thermoplastic resins such as polyphenylene sulfide and polysulfone. In the present invention, one kind or two kinds or more of these can be arbitrarily combined and used.

Examples of the polyether ketone include those represented by the following chemical formula 1.

[0051]

[Chemical 1]

Examples of the polyether ether ketone include those shown in the following chemical formulas 2 and 3.

[0053]

[Chemical 2]

[0054]

[Chemical 3]

Examples of the polyphenylene sulfide include those represented by the following chemical formula 4.

[0056]

[Chemical 4]

Examples of the polysulfone include those shown in the following chemical formula 5.

[0058]

[Chemical 5]

Various additives such as stabilizers and reinforcing materials may be added to the biomedical resin material 8.

The neck portion 3 and the stem portion 4 as described above
Is manufactured as follows, for example.

First, an aggregate of metal fibers 7 having a desired shape is produced, and the portion to be the neck portion 3 is filled with, for example, a compound (slurry) containing metal powder having a particle size of about 1 to 200 μm. Press-molded into the shape of the neck 3,
In a vacuum (10 ^-5 torr), for example, 500 to 1300
The neck portion 3 is formed by sintering (powder sintering method) under the condition of 60 ° C. for about 180 to 180 minutes.

Next, the aggregate of the metal fibers 7 in the portion to be the stem portion 4 is fixed in an injection molding die, and the biomedical resin material 8 is injected into the die and solidified to form the biomedical resin. Insert molding with the material 8 is performed. In this case, the injection condition depends on the type of resin material, but normally the mold temperature is 12
0 ~ 180 ℃, holding pressure at injection 120 ~ 600kg / cm ²
It is considered as a degree.

A separately manufactured metal or ceramic head 2 is connected to the neck 3 and the neck 3 of the stem 4 thus obtained to form the artificial joint of the present invention.

In the above powder sintering method, the composition of the metal powder used for sintering may be the same as or different from the constituent metal of the metal fiber 7, but the same component is used for the reason of obtaining sufficient bonding strength and toughness. Is preferably included.

From the viewpoint of such manufacturing technology,
The metal fibers 7 and the metal powder for sintering are preferably titanium, titanium alloy or stainless steel (in particular, SUS316L).

When the neck part 3 and the head part 2 are manufactured by integral molding, they can be simultaneously sintered and manufactured.

Although the artificial joint of the present invention has been described above based on the illustrated structural examples, the present invention is not limited to these.

The artificial joint of the present invention is not limited to the above artificial head, but may be, for example, an artificial knee joint, an artificial shoulder joint, an artificial elbow joint, an artificial finger joint, an artificial hip joint, or an acetabular cup embedded in the hipbone. Can also be applied to a part of.

[0069]

EXAMPLES Specific examples of the present invention will be described below.

Example 1 A hip joint artificial joint (artificial head) was manufactured by the following method.

[1] Manufacture of neck portion and stem portion First, a Ti-50% Ni alloy fiber having a fiber diameter of 0.5 mm was woven into a 20-mesh net shape and formed into a tubular shape 7.
Individual pieces (cylinder diameters in the range of 3 to 15 mm) were arranged substantially concentrically at intervals of 2 mm (see FIG. 3), and were hardened with gypsum leaving one end (15 mm in length) of them.

Next, the metal fiber net portion exposed from the gypsum was filled with a compound (viscosity 2000 cP) prepared by kneading titanium powder (average particle size 40 μm) and a 1% ammonium alginate aqueous solution as a binder, and applying an isotropic pressure device. Was pressure-molded to obtain the shape of the neck portion.

Then, this is placed in a vacuum (10 ⁻⁵ torr),
Firing was performed at 700 ° C. for 180 minutes to manufacture a neck portion made of a sintered metal containing metal fibers.

Next, after washing with 1N hydrochloric acid to dissolve and remove the gypsum, the gypsum was supported and fixed in a mold for injection molding, and the polyetheretherketone (Mitsui Toatsu pressure) shown in Chemical formula 3 above was used. (Manufactured by Mfg. Co., Ltd.) was injected and solidified, and insert molding was performed to obtain an integrally molded product of the neck portion and the stem portion.

The injection conditions are the molten resin temperature 365.
° C., mold temperature 165 ° C., was holding pressure 600 kg / cm ² during injection.

[2] Manufacture of head A spherical alumina head (bone head) is used rather than spherical alumina.
Was manufactured. A fitting hole for taper fitting was also formed in this head.

[3] Assembly The neck portion of the integrally molded product obtained in the above [1] is taper-fitted into the fitting hole of the head, and then the surface of the artificial joint is polished to obtain the book shown in FIG. An artificial joint of the invention was obtained. The dimensions and the like of this artificial joint are as follows. Head diameter: 38 mm Neck length: 35 mm Neck diameter: 15 mm Stem length: 120 mm Stem base major diameter: 40 mm Stem base minor diameter: 25 mm Stem tip outer diameter: 12 mm

Example 2 As an aggregate of metal fibers, a linear Ti-50% fiber having a diameter of 0.4 mm and a length of 140 mm was used.
Other than using a bundle of 1600 Ni alloy fibers,
In the same manner as in Example 1, the artificial joint of the present invention shown in FIGS. 1 and 2 was manufactured. The dimensions of this artificial joint are the same as those in the first embodiment.

Example 3 An artificial joint of the present invention shown in FIG. 3 was produced in the same manner as in Example 1 except that stainless steel (SUS316L) was used as the metal fiber and the sintering metal powder. The dimensions of this artificial joint are the same as those in the first embodiment.
Is the same as.

Example 4 An artificial joint of the present invention shown in FIG. 3 was manufactured in the same manner as in Example 1 except that Co-50% Cr alloy was used as the metal fibers and the sintering metal powder. The dimensions of this artificial joint are the same as those in the first embodiment.

Example 5 The artificial joint of the present invention shown in FIG. 3 is carried out in the same manner as in Example 1 except that the polyphenylene sulfide (manufactured by Philips) shown in Chemical formula 4 above is used as the biomedical resin material. Was manufactured. The dimensions of this artificial joint are the same as those in the first embodiment.

(Comparative Example 1) A neck portion and a stem portion are T-shaped.
An artificial joint was manufactured in the same manner as in Example 1 except that a solid integrally molded product made of an i-50% Ni alloy was used. The dimensions of this artificial joint are the same as those in the first embodiment.

(Comparative Example 2) The above-mentioned Example except that a solid injection molded product of polyetheretherketone (manufactured by Mitsui Toatsu Co., Ltd.) shown in Chemical Formula 3 above was used as the integrally molded product of the neck portion and the stem portion. An artificial joint was manufactured in the same manner as in 1. The dimensions of this artificial joint are the same as those in the first embodiment.

[Experiment 1] In each of the artificial joints of Examples 1 to 5 and Comparative Example 1 above, with the head facing upward, a line connecting the center of the head and the tip of the stem (about the axis of the neck). It was fixed so that the vertical direction was 25 degrees), and a load of 500 kgf was applied vertically downward to the head, and the amount of displacement of the head due to the load was measured.

As a result, when the displacement amount in the artificial joint of Comparative Example 1 is set to 1, the displacement amounts in Examples 1 to 5 of the present invention are 4.5, 2.5, 4.0 and 4, respectively. ．
It was 0 and 4.5. From this, it was confirmed that the artificial joints of Examples 1 to 5 of the present invention are all close to the bending elastic modulus of the living bone, and the stress transmission to the living bone is uniformly performed in a wider region.

[Experiment 2] In each of the artificial joints of Examples 1 to 5 and Comparative Example 2, with the head facing upward, a line connecting the center of the head and the tip of the stem (about the axis of the neck). (25 degree inclination) is fixed in the vertical direction, and a load of 300 kgf and 500 kgf is applied to the head vertically downward at 10 Hz.
Was applied for 24 hours, and the state of wear near the joint between the neck and the head was examined.

In the artificial joint of Comparative Example 2, about 0.001 g of abrasion powder of resin was observed on the test table, but in the artificial joints of Examples 1 to 5 of the present invention, abrasion powder was not generated at all. It was

[0088]

As described above, according to the artificial joint of the present invention, sufficient strength and durability can be obtained, the elastic modulus of the stem portion can be optimized, and the load can be applied uniformly over a wide range. As a result, bone destruction due to concentration of load and absorption of bone tissue due to no load are suppressed, and implantation and fixation in the bone marrow cavity can be made stronger and more reliable.

Further, since no abrasion powder is generated at the joint portion of the neck portion with the head portion, the proliferation of macrophages due to the abrasion powder is prevented.

Further, since the weight of the artificial joint is reduced, the burden on the patient can be reduced.

[Brief description of drawings]

FIG. 1 is a front view showing a configuration example of an artificial joint of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a transverse cross-sectional view of the stem base of the artificial joint of the present invention.

[Explanation of symbols]

 1 Artificial Joint 2 Head 3 Neck 4 Stem 5 Stem Base 6 Stem Tip 7 Metal Fiber 71 Tubular Body 8 Biomaterial

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Matsunaga 1463 Asama-cho, Hachioji-shi, Tokyo Within Jernome Machine Industry Co., Ltd. In-house (72) Inventor Ichiro Soga 1463, Sakuma-cho, Hachioji, Tokyo

Claims (6)

[Claims] 1. An artificial joint comprising a head made of a hard material, a neck portion following the head portion, and a stem portion following the head portion, wherein the neck portion is made of a metal containing an aggregate of metal fibers. The artificial joint, wherein the stem portion is obtained by embedding the metal fiber aggregate in a biomedical resin material. 2. The artificial joint according to claim 1, wherein the neck portion is formed by sintering the aggregate of the metal fibers by a powder sintering method. 3. The artificial joint according to claim 1, wherein the aggregate of metal fibers is a woven fabric, a knitted fabric, or a mesh of metal fibers. 4. The artificial joint according to claim 1, wherein the metal fiber is made of a shape memory alloy. 5. The metal fibers have a diameter of 0.01-2.
The artificial joint according to any one of claims 1 to 4, which has a diameter of 0 mm. 6. The biomedical resin material is at least one selected from the group consisting of polyetherketone, polyetheretherketone, polyallyletherketone, polyphenylene sulfide, and polysulfone.
6. The artificial joint according to any one of 1 to 5.