JP3214969B2 - Prosthetic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial prosthesis for replacing a hard tissue such as a bone or a joint of a human body whose function has been significantly reduced or lost due to various diseases, and more particularly to an artificial prosthesis and a living tissue. TECHNICAL FIELD The present invention relates to a prosthetic member having a porous surface structure for penetration of bone tissue and a method for manufacturing the prosthetic member, in order to enhance the support and fixation characteristics at the time of joining with a prosthesis.

[0002]

2. Description of the Related Art As a conventional artificial prosthetic member having a porous surface structure for penetration of bone tissue, for example, metal beads are sintered and fixed to the surface as disclosed in US Pat. No. 3,855,638 and US Pat. No. 4,644,942. Metal artificial prosthetic member, Metal prosthetic member obtained by compressing a metal mesh body and diffusion bonding to the surface by high-temperature heating as in the inventions of EP 0 178 650 and US Pat. No. 4,660,755. An artificial prosthesis member in which a metal plate is fixed to a surface by a mechanical method, as in the invention of US Pat. No. 4,608,052, an artificial prosthesis member in which fine holes are provided on the surface by laser processing to form a porous surface structure; As described in Japanese Unexamined Patent Publication No. Hei 3-123546, an artificial prosthetic member having a cast porous body fixed to its surface, As described in JP-A-3-29646, a metal artificial prosthesis member having a surface structure with holes having a shape substantially equivalent to that of cancellous bone tissue. In JP-A-3-49766, holes are formed by punching or etching. An artificial prosthetic member which is a porous body formed by laminating formed thin plates having a thickness of 150 to 500 μm, applying a compressive load thereto, and then heating, or part or all of the surface of the porous prosthetic member Many artificial prosthetic members and the like which have been coated have been proposed.

[0003]

However, the above-mentioned artificial prosthetic member has the following problems.

In the artificial prosthesis member, the volume ratio of the voids to the porous body, that is, the volume void ratio was as low as about 35%. When the volume porosity is small, even if the bone tissue fills the void, the relative volume is small, and thus the joint strength between the prosthetic member and the bone cannot be said to be sufficiently high. In addition, although metal beads are adhered to the surface, it has been found that the mechanical strength of the base constituting the artificial prosthetic member is significantly reduced due to high temperature treatment in the sintering step of attaching the beads. As an example, it has been reported that the fatigue strength is reduced to about 1/5 of the base metal strength, and the sintering process has had a great adverse effect on the durability of the prosthetic member in vivo. Furthermore, the beads fall off after sintering due to the low bonding strength between the beads,
There was a risk of intrusion into joint sliding surfaces and the like.

[0005] In the above-mentioned artificial prosthetic member, the volume porosity of the porous body is about 50%, and the fatigue strength is about 70% of the base material strength, which is improved as compared with the above-mentioned artificial prosthetic member. However, it was difficult to control the size and shape of the pores within a desired range. As a result, the diameter and shape of the formed pores are not optimal for the increased penetration of bone tissue,
Further, when trying to adapt the porous body to the surface shape of a complicated artificial prosthetic member, there is a disadvantage that the difference in compression load causes a large difference in the size and shape of the hole between the flat surface and the curved surface. As a result, the degree of penetration of the bone tissue into the pores differs depending on the part, and as a result, there is a problem that the joining strength between the porous body and the bone differs depending on the part.

In the above-mentioned artificial prosthetic member, since the plate-like body and the main body are mechanically connected, a minute movement occurs in the plate-like body, causing abrasion and melting of a metal structure, and in a severe case, the plate-like body may be displaced. However, there has been a problem that it is difficult to apply to a part having a complicated curved surface or a manufacturing cost is not low.

The above-mentioned artificial prosthesis member has a surface structure in which holes having a diameter of about 300 μm are regularly arranged. However, since the holes are not open pores that communicate with each other but closed pores that do not communicate with each other, the interprosthesis between the bone cells is reduced. The biological fluid does not flow, and the bone cells at the tip are necrotic.

In the above-mentioned artificial prosthetic member, it is difficult to apply it to a part having a complicated curved surface because the porous body is manufactured by casting, and the casting process is costly.

The above-mentioned artificial prosthetic member has a surface structure imitating the size and shape of cancellous bone. However, the size and shape of the holes in this structure are not necessarily optimal for invasion of bone tissue, and are not sufficient for bone tissue. There was a defect that did not occur.

In the above-mentioned artificial prosthetic member, since the thickness of the thin plate is as large as 150 to 500 μm, the porous body cannot be applied to a complicated curved surface or a cylindrical surface having a small diameter. In addition, the formation and arrangement of the holes are remarkably displaced by the addition of B, so that it is difficult to control the hole shape to an optimal shape for the invasion of bone tissue, and there is a problem that the invasion of bone tissue is not sufficient.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention relates to an artificial prosthetic member made of a metal material that is not harmful to a living body and has a site to be joined to hard tissue such as a bone or a joint of a human body. The artificial prosthetic member is formed by laminating a thin plate having a thickness of 150 μm or less in which a large number of pores are formed, and heating the same under no load to form a fusion-bonded porous body. The average particle size of the pores located in the surface layer in contact with is between 500 μm and 1000 μm, and the bond strength with bone 2 weeks after implantation in rabbits is 4.46K.
g / cm ² or more.

[0012]

The artificial prosthetic member of the present invention is obtained by laminating thin plates having a thickness of 150 μm or less and having a large number of pores formed therein, and heat-bonding them under a non-load. It is possible to form a porous body that is three-dimensionally connected and the connection is controlled, and can be formed according to the shape of a complicated member surface. Further, the average pore diameter of the pores located in the surface layer in contact with the hard tissue is 500 to 10
Since the bond strength with bone was 2.46 kg / cm ² or more two weeks after implantation in the rabbit, the bone was implanted in the body and the bone was formed inside the porous body. Sometimes the bone diameter at the interface between the porous body and the bone is large,
Bone is less likely to break. According to the present invention, with such features, the prosthetic member and the bone tissue are firmly fixed, thereby improving the durability, and the burden on the patient can be greatly reduced because there is no need for replacement surgery. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a perspective view of a porous body S according to the present embodiment, which constitutes an artificial prosthetic member or covers part or all of the surface of the artificial prosthetic member. This porous body S has an outer dimension of 10 mm × 15 mm × 2 mm and a thickness of 100 mm.
Thin plate 1, 2 with many pores H in μm
Are sequentially stacked to form a 20-layer laminated structure. Further, in the porous body S, in the thin plate constituting the surface in contact with the bone, for example, the thin plate 1, the average pore diameter of the pores H is in the range of 500 to 1000 μm.

The material of the thin plates 1, 2,... Is pure titanium,
After positioning the thin plates 1, 2, ... while stacking them, and temporarily fixing them with a light weight or an adhesive, the thin plates 1, 2, ... are heated to about 900 degrees under substantially no load in a vacuum sintering furnace.
Were fused together. The sintering furnace uses a molybdenum heater, and the heating may be performed in an inert gas atmosphere such as argon. The fusion of the thin plates 1, 2,... Is performed by diffusion bonding of metal atoms. In addition,
The positioning of each of the thin plates 1, 2,... Was performed by using each piece of the thin plate having a rectangular shape in plan view.

Further, in the process in the vacuum furnace, the pores H may cause a slight displacement at the overlap, but the displacement amount is about 2
It is about 0 μm and can be almost ignored in production. In the case where it is necessary to stack the sheets more accurately, or in the case where the outer shape of the porous body S does not have a flat portion that can be used as a reference, holes (not shown) for positioning are formed on each of the thin plates 1 and 2.
.. May be formed at the four corners, and a positioning rod may be inserted here. In this way, the thin plates 1, 2,... Were fused together, but there was no particular change in the appearance and dimensions of the porous body S1, and no altered layer was observed.

The regular hexagonal pores H are formed by etching, but can also be formed by laser processing, punching, or the like.

FIG. 2 is a sectional view taken along line II of FIG. In order to design the distribution of the pores H, the pores H in the n-th row and the m-th column of the first layer are defined as 1Hnm.
Are pores in the first row and the first column of the first layer. .. Having a thickness of 100 μm are stacked to form pores 1H11, 2H1
1 is in communication. However, in the actual porous body S, each layer is often slightly shifted as described above.

When the thin plate is corroded from both sides in the step of showering the etching (corrosion) solution to form the pores H, the cross section thereof is formed by a protrusion h projecting toward the center of the pores H as shown in FIG. It becomes a shape close to a rhombus, and the angle of the slope is in the range of about 30 degrees to about 45 degrees. When the etching is performed from one side, the cross section becomes a shape close to an isosceles triangle.

Whether to perform etching from both sides or from one side is determined in consideration of the shape of the artificial prosthetic member and the biomechanical conditions of the portion of the hard tissue to be replaced. That is, it is necessary to consider what kind of stress remains on the surface of the porous body S, how much the stress is, and the like. In the case of fixing using bone cement, a design in which the bone cement easily enters the pores H and hardly comes off after polymerization is better.

Since the metal thin plates 1, 2,... Constituting the porous body S of this embodiment have a thickness of 150 μm or less, they can be easily formed, and are heated under substantially no load. By fusing and bonding, the pores H are connected three-dimensionally, and the porous body S whose connection is appropriately controlled is formed and fixed in accordance with the complex surface of the artificial prosthetic member. Can be. The planar shape of the pores H is preferably selected to be a shape effective for close packing, such as a regular hexagon, and shaped so as to increase the volume porosity as much as possible. It is desirable that H has an open three-dimensional structure that extends not only in the vertical direction but also in the horizontal direction.

In the thin plate constituting the surface in contact with the bone, for example, the thin plate 1, the average diameter of the pores H is 500 to 500.
Since it is in the range of 1000 μm, a sufficient amount of bone penetrates into the inside, and the diameter of the bone at the invasion site is large. Large binding force. On the other hand, when the pore size is 500 μ
If it is less than m, the bone may be broken at the interface between the porous body S and the bone.

Further, in order to promote the penetration of bone tissue, it is desirable to coat a bioactive biomaterial which has an affinity for the bone tissue and is biocompatible. The material to be coated is apatite, bioglass ceramic, chitin, chitosan. It is desirable to coat titanium oxide or titanium nitride which is excellent in corrosion resistance in a living body together with, for example, gelatin or a derivative thereof. Further, when the artificial prosthesis member is fixed with bone cement, it is desirable to coat an agent such as a silane coupling agent that enhances adhesive strength with the bone cement.

The metal materials constituting the thin plates 1, 2,... Are pure titanium, titanium alloy, CoCrM
It is preferable to use an o alloy or a FeNiCr alloy.

3 to 5 show different cross-sectional structures of the porous body S. FIG. 3 shows thin plates 1, 2,.
The effective size of the pores H formed in the porous body S becomes smaller as it approaches the prosthetic member base I from the bone tissue side B.
2 shows the cross-sectional structure of the device. FIG. 4 shows a cross-sectional structure opposite to that of FIG. This is an effective cross-sectional structure particularly when a tensile stress in the vertical direction is generated on the surface of the porous body S. FIG.
Shows a cross-sectional structure in which the pores H formed in the second thin plate 2 and the fourth thin plate 4 from the top are much larger than the other thin plates.

[0026] Animal experiments Animal experiments were used five types of porous material S having an outer shape of 10 × 15 × 2.0mm.

The porous body S is composed of nine non-porous thin plates sandwiched at the center and nine on each side, that is, a total of eighteen thin plates of pure titanium (10 in total).
(× 15 × 0.1 mm) prepared according to the method described above, and narrowed from the outermost layer pore diameter of 500 μm to the deepest layer (that is, the thin plate adjacent to the central nonporous thin plate) with a pore diameter of 150 μm (sample 1). , The opposite surface pore diameter of 1
A sample in which the diameter is increased from 50 μm to the deepest hole diameter of 500 μm (sample 2), a thin plate having a hole diameter of 500 μm is stacked (sample 3), a thin plate having a hole diameter of 150 μm is stacked (sample 4), and a thin plate having a hole diameter of 800 μm is stacked (Sample 5).

In these samples 1 to 5, thin plates having a hole diameter of 1000 μm were laminated in order from the surface side in order to have a structure in which the pores H communicated.

FIGS. 6 to 8 are schematic diagrams of animal experiments performed to examine the effectiveness of the porous body S manufactured as described above. The experimental method is Journal of
Biomedical Materials Rese
arch, Vol, 19, pp. 685-698 (19
85).

That is, NZW rabbits (12 weeks old; △) 3
Using 0 birds, Nembutal anesthesia was performed according to the conventional method, and then an incision was made from the inside of the proximal end of the tibia T to expose the bone surface. Then, as shown in FIG. 6, a 2 × 15 mm cavity penetrating the cortical bone was formed. Was hammered and implanted, sutured as usual, and left in a cage.

The animals were sacrificed 2-6 weeks after the operation under excessive Nembutal anesthesia, and the tibia T containing the sample S as shown in FIG.
The bone block was cut out.

After trimming the bone block without fixing the tissue, the bone block is mounted on an Instron testing machine as shown in the schematic diagram of FIG.
The bonding strength between the tibia T and the sample S was measured at 5 cm / min. The bonding strength was determined by measuring the area where the surface of each sample S was in contact with the bone material from a section and converting the area per unit area. Table 1 shows the results.

[0033]

[Table 1]

As shown in Table 1, in the two-week implantation example, Samples 2 and 4 having a surface layer pore diameter of less than 500 μm were 2.87 ± 0.36 Kg / cm ² and 2.93 ± 0.35, respectively.
Kg / cm ² , but the pore size of the surface layer is 50
Samples 1, 3, and 5 each having a size of 0 μm or more were 4.99.
± 0.53 Kg / cm ² , 6.13 ± 0.79 Kg / c
m ² , a very high value of 7.27 ± 0.86 Kg / cm ² .

After this test, the bone block fixed to one end of the sample S was fixed in a tissue with a 10% neutral buffered formalin aqueous solution, dehydrated in ascending ethanol, and embedded in a polyester resin. The embedding block was sliced perpendicularly to the long axis of the bone at the center of the sample S and at a position 4 mm away from the center, respectively, and polished to a thickness of about 70 to 80 μm.

The obtained non-demineralized polished sections were stained with TB to observe the degree of invasion of new bone tissue.

As a result, invasion of immature new bone was observed as early as 2 weeks in the entirety of samples 1 to 5, but in 6 weeks, bone maturation progressed and integration with existing cortical bone was observed. On the other hand, Samples 2 and 4 in which the pore size of the surface layer is less than 500 μm
Invasion of mature bone was limited to near the surface.

[0038]

As described above, the artificial prosthetic member of the present invention is
Since a thin plate having a thickness of 150 μm or less, in which a number of pores are formed, is laminated and heated and fused under non-load to form a porous body, the pores are three-dimensionally connected and connected. It is possible to be a controlled porous body,
Furthermore, it can be molded in accordance with the complicated shape of the member surface. The average pore diameter of the pores located in the surface layer in contact with the hard tissue is 500 to 1000 μm, and the bond strength with bone 2 weeks after implantation in a rabbit is 4.46 Kg / cm.
Since it is ² or more, when the bone is implanted in the body and the bone is formed inside the porous body, the bone diameter at the boundary surface between the porous body and the bone is large, so that the bone is not easily broken. Become. According to the present invention, with such features, the prosthetic member and the bone tissue are firmly fixed, thereby improving the durability, and the burden on the patient can be greatly reduced because there is no need for replacement surgery. .

[Brief description of the drawings]

FIG. 1 is a perspective view of a porous body as a bioprosthetic member according to an embodiment of the present invention.

FIG. 2 is a II diagram of the porous body of FIG.

FIG. 3 is a vertical sectional view of the porous body of FIG.

FIG. 4 is a vertical sectional view of the porous body of FIG.

FIG. 5 is a vertical sectional view of the porous body of FIG. 1;

FIG. 6 is a schematic diagram of animal experiment 1.

FIG. 7 is a schematic diagram of animal experiment 1.

FIG. 8 is a schematic diagram of animal experiment 1.

[Explanation of symbols]

 S porous body 1-20 thin plate H pore B bone tissue, bone marrow tissue T tibia F femur W wire

Claims (1)

(57) [Claims] An artificial prosthetic member made of a metal material having no harm to a living body and having a site to be joined to hard tissue such as a bone or a joint of a human body, wherein the artificial prosthetic member has a large number of pores. There laminating thickness 150μm following thin plate formed by drilled, non load
A porous body that is heated and fused under heat, and has a mean particle diameter of pores located in a surface layer in contact with the hard tissue in the porous body, of 500 μm to 1000 μm ;
The bond strength with bone 2 weeks after implantation in rabbits is 4.46K.
g / cm ² or more .