JPS6359965A - Artificial joint member - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an artificial joint member for restoring functions lost in the human body due to disease, disaster, etc.

C. Prior art] When joint function in the limbs is impaired due to bone diseases such as osteoarthritis or chronic rheumatoid arthritis, artificial joint replacement surgery is often performed as an open treatment in orthopedics. There is.

There are 20,000 cases a year, especially on one side of the hip joint, which is a load-bearing joint.

Currently, many artificial joints are made of metal and plastic, and include a wide variety of artificial hip joints and knee joints.

The biggest problem common to these artificial joints is loosening (looseness during use). In other words, several years after artificial joint replacement surgery, loosening occurs between the artificial joint and the living bone, resulting in pain and a decline in joint function, which often negates the need for removal and reoperation. .

There are various possible causes of loosening, but the most likely causes are the heat generated by the bone cement (acrylic instant polymerization range) used to fix the artificial joint to the end of the bone joint in the human body during surgery and the toxicity of the monomer.

In order to avoid loosening caused by bone cement, a cementless joint has been devised in which the surface of the stem (femoral part of the artificial hip joint) is made uneven. However, this cementless artificial joint requires a long period of time for bone repair after surgery, and requires a load relief period of several months, so the number of cases in which it is applied is small.

Current orthopedic surgery InBlan 1 research focuses on the problem of bone repair in cementless artificial joints, and aims to shorten the unloading period by adding metal beads and mesh to the surface of the stem to promote bone growth and penetration. efforts have been made. However, problems such as increased elution of metal ions and deterioration of the metal substrate and fatigue strength arise due to the addition of metal beads or meshes, and there are also reports of osteoporosis occurring in clinical cases. (J, B,, 1.S, νol 67-8.
Na2. MARCH1985, P218-221).

Therefore, attempts have been made to coat bioactive materials such as bioglass and hydroxyapatite in place of metal beads and mesh, and have achieved good results in animal experiments.

[Problem that the invention seeks to solve]

Various methods of coating bioactive materials on metal substrates have been studied, but the most practical and reliable method is the thermal spraying method of hydroxyapatite (for example, Japanese Patent Publication No. 58-39533). However, the ceramic layer formed by thermal spraying is essentially a porous body, and is an extremely fragile layer because it is originally a calcium phosphate ceramic with low strength. Therefore, although the artificial joint is fixed in a relatively short time after implantation into the bone, repeated stress due to loading may cause interlaminar fracture within the coachib layer.
Causes loosening. Some attempts have been made to improve this phenomenon by carving grooves on the surface of the base, but micro-movement occurs due to minute load fluctuations during walking, and the generated tensile force and shear stress lead to similar failure. The meaning of coating with bioactive materials will be lost.

[Means for solving problems]

The present invention was made in view of the problems of artificial joints coated with bioactive materials, and aims to solve the problems by eliminating the coating layer after the artificial joint is fixed. .

Commercially available calcium carbonate (CaCOs) and calcium birophosphate (CasPzOt) were mixed at Ca/P ratio (molar ratio).
The mixture is mixed at a temperature of 1.3 to 1.5 degrees and calcined and ground at a temperature of 1100 to 1700 degrees Celsius. The resulting calcium phosphate salt is Ca1(P
It becomes a mixture mainly consisting of Oa)z. After pulverizing and classifying the powder to a predetermined fineness, it is coated on a metal substrate by thermal spraying. The final coating layer obtained by adding post-treatment such as heat treatment to this is CaIo (PO4
)6(OH)2 and Ca3(Pot)z. The abundance ratio of both can be controlled by changing the Ca/P ratio.

Ca Ho (PO4)6 (OH) z is insoluble, C
a5(POt)z is a soluble material, and by changing the abundance ratio of both, the dissolution characteristics and disappearance time in the living body can be controlled. The present invention is coated with a bioactive material whose disappearance time can be set in this manner.

〔Example〕

Hereinafter, the present invention will be specifically explained in detail with reference to Examples.

(Example 1) Commercially available CaC0, Ca, PzO, Ca/P = 1.4
The mixture was mixed for 15 hours at a ratio of 5:5, dried at 50°C for 12 hours, and then fired at 1300°C for 2 hours. The baked powder was dry-pulverized and classified to a particle size of 350 mesh or less, and then coated on the stem of an artificial joint in use by plasma spraying (W, 20 μm). They were then heat-treated at 800°C for 2 hours and then surgically implanted into three pegle dogs.

CaIo(Pot)i(OH)z and Caa(POt)
The abundance ratio of z was 100:20. X over time after surgery
Upon line observation, it was found that it was fixed to the bone in about 4 weeks, and the coating layer disappeared on all three animals in about 3 months. Even after the coating layer disappeared, the artificial hip joint and fixation were sufficient, and there were no signs of loosening even one year after the surgery.

(Example 2) In the same method as in Example 1, in a material blended at Ca/P=1.40, CaIo(POa)6(OH)z and Ca
The abundance ratio of 5(POt)z was 100:50.

The coating was applied to the entire surface of a cylindrical test piece with a diameter of 8 mm and a length of 8 mm, and when implanted into the femur of an adult mongrel, the bone surrounded the entire circumference in about 4 weeks, and the coating layer disappeared in about 2 months. Ta.

(Example 3) The mixture was blended in the same manner as in Example 1 to a ratio of Ca/P = 1.30, and after baking and pulverization, 1 part by weight of calcium fluoride = 6- (CaFz) was added, plasma sprayed, When heat treatment was performed, Ca 1 o (POJ 6 (OH)
The abundance ratio of Z and Cat(PO)4 was 100:80. When a coated cylindrical test piece with a diameter of 811IllI and a length of 8m+n was implanted into the femur of an adult mongrel, bone surrounded the entire circumference of the test piece in about 3 weeks, and the coating layer disappeared in about 1 month.

(Example 4) 20 stacked portions of A120i fine powder (average particle size 5 μm) were added to the classified powder prepared in Example 1 and dry mixed.

This was plasma sprayed onto artificial hip joints for dogs and heat treated.

Ca + o (PO4)b (OH) t and CRs
The abundance ratio of (POa)x was 100z10. Two peagle dogs underwent surgery and underwent X-ray observation over time. The bone surrounded the bone in about 4 weeks, but it took about 5 months for the coating layer to dissolve.

As shown in the above examples, the present invention provides Ca + o
(PO4)6(OH)2 and Ca3(PzO)t
By changing the abundance ratio of , it is possible to set and control the elution time in the living body. Although additives were used in Examples 3 and 4, CaFz, Ti0z+Zr
0z has the effect of increasing the abundance of Ca(PO4)z, A 1203 + T I C + S I 3 N
a has the effect of reducing the amount of Ca3(POa)z. Of course, coatings with similar elution characteristics can be obtained by thermal spraying methods other than plasma spraying, ie, flame spraying and rod spraying.

It is also possible to form a coating with the same effectiveness using methods other than thermal spraying, such as ion blating or sputtering, which can also produce a dense calcium phosphate film. This film is an amorphous film, and even normally insoluble hydroxyapatite is soluble. However, it has been found that the hydroxyapatite coating with a layer thickness of 2-3 μm obtained with conventional coatings disappears within 2-3 weeks after implantation.

Furthermore, if the thickness can be increased to about 30 μm, the disappearance period can be extended to about 2 months. It is thought that if the thickness is further increased, the disappearance period can be further extended, but as the thickness increases, peeling becomes easier, so the upper limit is about -40p. The settable period is shorter than the thermal spray method.

〔Effect of the invention〕

As mentioned above, the drawback of the conventional bioactive material coating method (spraying method) applied to cementless artificial joints is the interlayer breakdown of the coating layer, and if interlayer breakdown occurs, it will cause loosening and the bioactive material coating However, the present invention aims to solve this problem by eluating the bioactive material coating layer after fixing the artificial joint and eliminating the layer that causes destruction. You can freely set and control the time of disappearance. Therefore, in the case of young patients with strong bone formation ability, it will disappear in about 1 to 2 months, in the case of young patients, it will take 3 to 4 months, and in patients with worse bone formation depending on the disease state, it will disappear in about 4 to 5 months. It becomes possible to set the time of disappearance that is appropriate for each patient, and it becomes possible to provide a high-performance artificial joint that can appropriately save many patients suffering from the disease.

Claims (1)

[Claims] An artificial joint member characterized in that a bioactive material containing a biosoluble material is adhered to at least the surface portion of a base body made of a metal material that comes into contact with bone.