JPH02114960A - Artificial bone - Google Patents

Abstract

PURPOSE:To eliminate exfoliation, detachment and chipping by forming a surface layer gradually increasing in the concn. of the constitutional elements of an biologically active inorg. material toward the outer surface thereof to the surface layer part of a core material composed of a metal material or high strength ceramics material. CONSTITUTION:As a core material of an artificial bone, a metal material such as SUS 316 or a high strength ceramics material is used and a surface layer based on biologically active inorg. material components strongly integrated with the core material is formed to the surface layer part of the core material by the ion injection of the constitutional elements of the biologically active inorg. material or by the combination of the vapor deposition of the core material and the ion injection of said constitutional elements. This biologically active inorg. material has characteristics reacting with the peripheral bone tissue in a living body to form the strong chemical bond to a natural bone and, for example, apatites are used to bring about biocompatibility and natural bone bondability. By this method, the inorg. material can be bonded to the natural bone rapidly and fast fixing can be kept over a long period of time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an artificial bone for filling bone defects in a living body, which forms a strong bond to the remaining autologous bone at an early stage, Furthermore, the present invention relates to an artificial bone that can firmly maintain its strong bond over a long period of time.

[Prior Art] When canal damage occurs due to an accident, disease, tooth extraction, etc., artificial bone is required to fill in the bone defect or void.

It goes without saying that such artificial bone has a strength commensurate with the replacement site and is harmless to living organisms, and it is quickly and firmly fixed to the autologous bone and does not loosen over long-term use. It must be something similar.

As artificial bone materials, stainless steel such as 5US316, T
Metal materials such as Ti and Ti alloys, and pitalium, and high-strength ceramic materials such as alumina, zirconia, and silicon nitride have been used. However, these materials are selected based on their corrosion resistance and mechanical strength, and their affinity for living organisms and bonding properties to autologous bone are insufficient.

On the other hand, bioactive inorganic materials such as apatites, especially hydroxyapatite [C
Inorganic materials containing aro (P 04)a·(OH)2] and apatite are known. Although these materials have excellent biocompatibility and autogenous bone integration, they have the drawback of extremely low mechanical strength.

Therefore, a composite material that combines the advantages of both has been proposed, and for example, Japanese Patent Application Laid-open No. 82893/1983 describes that ``The core material of a metal implant is thermally sprayed coated with hydroxyapatite powder or a composition powder containing the same. JP-A-60-116362 discloses ``a core material made of metal, alloy, or high-strength ceramics, and a surface of the core material containing at least 25% by weight of CaO and P2O in total. "Artificial bone and artificial tooth root coated with glass or glass ceramics" are disclosed.

Furthermore, Japanese Patent Application Laid-open No. 62-57548 states that ``a powder containing hydroxyapatite is thermally sprayed onto the surface of a core material made of metal using a thermal spraying device, and then the sprayed material is coated with calcium oxide without substantially dissolving the hydroxyapatite. An intraosseous implant in which alkaline eluted components are removed by treatment with an aqueous solution capable of dissolving the alkaline components is disclosed.

The common basic structure of these composite materials is that the surface of metal materials such as stainless steel, titanium, titanium alloys, Co-Cr alloys, etc. is coated with hydroxyapatite or bioactive glass by thermal spraying or chemical precipitation to bond the metal and bioactive glass. The point is that the active materials are composited.

[Problems to be solved by the invention] These composite materials are materials that have mechanical strength due to the core material and biocompatibility and autogenous bone integration properties due to the covering material, but the core material and the covering material are originally different. If the core material is directly coated with the covering material as in the disclosed example, the bonding strength at the interface between the two will be insufficient, and after long-term use, There is a problem in that when a large external force is applied, the bonded portion between the two may peel off, fall off, or be damaged.

In view of this situation, in the present invention, an artificial bone material that not only has good mechanical strength, biocompatibility, and autogenous bone integration, but also does not peel off or fall off during use, has been investigated.

[Means for Solving the Problems] The artificial bone of the present invention that can solve the above problems uses a metal material or a high-strength ceramic material as a core material, and a bioactive inorganic material component in the surface layer of the core material. By ion-implanting each element, or by combining the vapor deposition of the core material component and the ion implantation of the bioactive inorganic material component element, the surface of the core material has a bioactive material that is highly integrated with the core material. The main feature of this artificial bone is that a surface layer mainly composed of inorganic material components is formed, and the surface of this artificial bone is coated with a bioactive inorganic material, and has excellent biocompatibility and autogenous bone integration.

[Function] The metal material or high-strength ceramic used as the core material in the present invention must have sufficient strength and have extremely little harmful effect on the human body. Examples of such materials include stainless steel such as 5U5316, titanium alloy such as RT or Ti-6AI-4V, Co-Cr
Examples include metal materials such as alloys, and high-strength ceramic materials include alumina, zirconia, silicon nitride, and the like.

Furthermore, bioactive inorganic materials have the property of reacting with surrounding bone tissue in vivo and forming strong chemical bonds with autologous bone, such as apatites, especially hydroxyapatite [Ca. (PO4)6・(OH)2], alumina or zirconia ceramics containing apatite,
β-3CaO.

P, O! , Na20-CaO-3in2P20!1
Examples include glass-based glass (bioglass), apatite-containing crystallized glass as shown in Table 1, and the like.

The characteristics of the ion implantation method are that it is possible to add elements that do not dissolve in metals, that it can be added at room temperature, that the amount of implantation can be adjusted relatively easily by controlling the ion current or time, that the depth of addition can be adjusted, and that For example, elements can be highly purified. The present invention utilizes the characteristics of such an ion implantation method, and the means for forming the surface layer formed on the surface of the core material, which is mainly composed of a bioactive inorganic material component that has strong integration with the core material, is as follows. It is broadly divided into two methods.

■Ion-implant each of the constituent elements of bioactive inorganic material into the surface layer of the core material.

■ Combining vapor deposition of core material components and ion implantation of bioactive inorganic material components.

Next, the ion implantation method employed in the present invention will be explained.

First, regarding the above-mentioned (2), an example of Ca ion implantation will be explained as follows. Figure 1 shows the core material (e.g. Ti-6).
Ca was implanted into AI-4V alloy at an energy of 50 keV.
Ion implantation at a dose rate IXLO 171 ons/cm2 and an implantation energy tookeV,
This figure shows the relationship between the depth position from the surface and the Ca atom concentration for ions implanted at a dose rate of 5×10 I7 tons/cm 2 . The total amount of ion implantation is determined by electric residue x time = quantity of electricity, and the concentration distribution and depth vary depending on the implantation energy (implantation voltage) and the type of material to be implanted. Since the concentration distribution state differs depending on each element, when implementing the present invention, it is necessary to know in advance the relationship between the injection conditions and the concentration distribution and depth state in the surface layer of the core material for each component element of the bioactive inorganic material. It is desirable to set injection conditions for each element such that the desired bioactive inorganic material constituent composition is formed in the surface layer of the material.For example, when injecting a hydroxyapatite component, Ca:P:O: H
= Ca so that the composition ratio is 10:6:26:2.
, P, O, and H are each ion-implanted. When it is desired to form other bioactive inorganic materials, ion implantation is performed in the same way as above to achieve the desired component composition ratio.In the outermost layer of the layer obtained in this way, each component has a Gaussian distribution. (See Figures 1 and 2), and since the concentration is generally low on the outermost surface side and the desired component concentration cannot be obtained, the surface is polished to a depth that shows the optimum composition concentration value. It is desirable to do so (see Figure 3).

As the vapor deposition means used in conjunction with the method (2), ordinary vapor deposition methods such as EB vapor deposition, ion blasting, and sputtering can be used. At this time, 1 of the core material constituents
The vapor deposition of one or more species and the ion implantation of one or more elements constituting the bioactive inorganic material may be performed simultaneously, or the vapor deposition and ion implantation may be performed alternately, but these operations can be performed in the following manner. It is better to repeat the process repeatedly (however, when performing vapor deposition and implantation at the same time, both the vapor deposition element supply device, such as the EB heating melting device and the ion gun, which is the supply source of the ion implantation elements, must be installed in the processing chamber, so the device must be (complicated).

That is, initially, the ratio of the amount of vapor deposition of the core material was increased and the ratio of the amount of implanted Ca and P ions, which are the main elements of bioactive inorganic materials, was decreased, and as the layer thickness increased, the ratio of the latter was increased, and In addition to Ca and P, O and H are also injected from nearby areas (there is a risk of embrittlement of the material if O and H are added from the beginning), and in the outermost layer, Ca, P, O, and H are injected into the outermost layer.
Perform ion implantation of only bioactive inorganic materials. Similar to the above-mentioned case (2), the ion implantation in (2) requires knowledge of the implantation conditions and the concentration distribution state of each component element before performing the ion implantation.

If it is desired to make the ion-implanted layer thicker, the ion implantation may be performed by changing the implantation energy in (1) above, and the resulting layers may be stacked in several layers in (2).

The ion-implanted layer formed on the surface layer of the core material as described above has a lower concentration of bioactive inorganic material components in the deeper part.
These atoms exist in the voids between atoms forming the crystal lattice of the core component, or in a state where they are replaced with those atoms and are integrated with the core component inside the crystal. The concentration increases toward the surface, and the composition of the bioactive inorganic material is almost as desired at the outermost surface. That is, a film of a bioactive inorganic material component that is highly integrated with the core material is formed on the surface of the core material.

Therefore, when an artificial bone having such an ion-implanted layer is used to fill a bone defect, it exhibits biocompatibility and has strong bonding properties to autologous bone.

Furthermore, in order to increase the thickness of the bioactive inorganic material layer, the bioactive inorganic material layer may be formed by a chemical method such as a sol-gel method or by other methods.

These artificial bones are used in the hip joint, knee, elbow, and shoulder.

It can be used as a substitute for joints such as fingers, other long bones, etc., or for artificial tooth roots.

[Example] Example 1 Using a Ti-6AI-4V alloy as the base material, Ca was implanted at an energy of 100 keV (Doseley)-1.9x
Ion implantation was performed under the condition of 10" tons/cm2,
Roughly P 100 ke V, 1.1 x 10
Ion implantation was carried out under the conditions of "tons/cm2.Similarly, O was implanted at 100 k e V, 5.Ox 101
7 tons/cm'H at 100 k e V,
Injection was performed under the condition of 0.38x 1017 tons/cm'.

FIG. 2 shows the AES profile of the surface of this sample in the depth direction. As is clear from FIG. 2, the surface layer had a composition close to hydroxyapatite. In particular, since the optimum composition value existed within a small distance (approximately 0.1 μm) from the surface layer, in practical use, the surface was polished by about 0.1 μm until the optimum component composition was exposed on the surface. Third
The figure shows the results of AES analysis after polishing. The component ratio of the outermost layer is Ca: P: O: I (-9: 5
:28:2, and hydroxyapatite Ca:
The composition was extremely close to P:O:H-10:6:26:2.

Example 2 A Ti-6AI-4V alloy was used as a base material, and while Ti was being vapor-deposited, Ca was ion-implanted (ion mixing) at an implantation energy of 100 keV and a dose rate of 1.9 x 10" 1 ons/cm". The film formation rate of Ti vapor deposition was 2 A/sec. In this way, 1 μm
A thick film was formed. This sample was further implanted with an energy of 100 KeV and a dose rate of 1. Ox 1017
Ca was injected at tons/cm2, followed by P at 100
k e V , 1.1 x 10”1ons/cm2
, O at 100 k e V, 5. Ox 10"to
ns/cm2, H at 100k e V, 0.38x
Ion implantation was performed under the condition of 10 I7 ions/cm'.

When we looked at the atomic concentration profile of this sample in the direction of surface depth using AES, it was as shown in Figure 4, and T 1-6A.
1-4V (D It is clear that a Ti film is formed on the base material.Ca that has undergone ion mixing is uniformly distributed from the base material surface to the Ti vapor deposited film, and this Ca This is useful for strengthening the adhesion between the material and the Ti film. Furthermore, when the surface was polished to a depth of about 0.1 μm in the same manner as in Example 1, the same results as in Example 1 were obtained.

Example 3 Using Ti-6A1-4V alloy as the base material, (1) T
i -e A 1-4 V alloy deposition rate 2 persons/se
While depositing with c, the injection energy of ca was 100 keV.
, Dose rate 0.6 x 10”1oz/c
Ion implantation (ion mixing) was performed at m2. Next, the same titanium alloy was deposited in the same manner, and P was applied at 100 k e V.
, ion implantation (ion mixing) was performed at 0.4 x 1017 tons/cm2.

(2) Vapor deposition rate of Tf-6AI-4V alloy roughly 1.4
Ca was evaporated at A/sec at 100 keV! , 2x
Ion implantation was performed at 10" tons/cm2, and then the same titanium alloy was similarly deposited while P was applied at 100 keV.

Ion implantation was performed at a dose rate of 0.8 x 10171 ons/cm2.

(3) Furthermore, the Ti-6A1-4V alloy was deposited at a evaporation rate of 0.
．． Vapor deposition was performed at 7 A/sec, Ca was evaporated at 100 k e V,
Ion implantation was carried out at 1.9 x 10" fans/cm2, and then the same titanium alloy was deposited in the same manner while 100% P was added.
k e V, 1.1 x 10” 1oz/cm
”Ion implantation was performed.

(4) In this way, Ca and P were ion-implanted alternately while depositing TL-6AI-4V alloy to form a 1 μm thick film, and then Ca was roughly added to the sample at 100 k e V.
Ion implantation was performed at 1.9 x 10I7tons/cm", followed by P at 100 k e V, 1.1 x 1
0” tons/cm2, then O at 100 keV,
5. OxlO17tons/cm2, H 100
k a V , 0.38x 10'71ons/cm
Ion implantation was performed in step 2.

The element concentration profile in the depth direction of the surface of this sample was examined using an Auger analyzer, and the profile was as shown in FIG. Ti-A on Ti-6A1-4V alloy base material
An I-V alloy film is formed, and Ca and P are alternately injected from the base metal surface to the titanium alloy film, and the concentration gradually increases.
P firmly bonds the base material and the surface layer. Further, a film similar to that in Example 1 was formed on the outermost surface side.

Example 4 A chemical method (
A hydroxyapatite layer coating with a thickness of several μm was formed using a sol-gel method. In this example, hydroxyapatite cores have already been formed on the surface of the core material, and the hydroxyapatite is coated on top, so the bonding strength is lower than that of the prior art, in which hydroxyapatite is directly attached to the Ti material on the core material. It has improved a lot.

Furthermore, when the sample (artificial bone) obtained in the same manner as in Example 4 was implanted in the hip joint of a dog, it merged with the living bone after 14 days.
I can now walk.

〔Effect of the invention〕

Since the present invention is constructed as described above, the artificial bone of the present invention can be bonded to the autologous bone at an early stage, and can maintain firm fixation over a long period of time.

[Brief explanation of drawings]

Figure 1 shows an example of Ca ion implantation into the core material (TL-6AI-4V alloy), and Figure 2 shows the core material (TI-6AI-4V alloy).
When ion-implanting ca, P, O, H into 4V alloy),
Figure 3 is a concentration diagram of the ion implanted material obtained by polishing the outermost surface of the ion implanted product with the concentration shown in Figure 2. Figure 4 is a diagram of the concentration status of the ion implanted material in the surface layer.
Fig. 5 is a surface layer concentration state diagram when Ca is ion-implanted while Ti is vapor-deposited on the core material (T i -6A 1-4V alloy), and Ca, P, O, and H are further ion-implanted.
Alloy) C while depositing T 1-6A l-4V alloy on top
After ion implantation of a and P alternately, Ca, P, and O
, H is a concentration state diagram of the surface layer portion when ions are implanted.

Claims (3)

[Claims] (1) A metal material or a high-strength ceramic material is used as the core material, and a surface layer is formed in the surface layer of the core material in which the concentration of the constituent elements of the bioactive inorganic material gradually increases toward the outer surface. artificial bone. (2) By using a metal material or a high-strength ceramic material as a core material and ion-implanting the constituent elements of a bioactive inorganic material into the surface layer of the core material, or by vapor deposition of the core material constituent elements and a bioactive inorganic material. An artificial bone characterized in that a surface layer mainly composed of bioactive inorganic material components having strong integration with the core material is formed on the surface of the core material by combining ion implantation of material constituent elements. . (3) An artificial bone obtained by coating the surface of the artificial bone according to claims (1) and (2) with a bioactive inorganic material.