JPH01212551A - Artificial bone - Google Patents

Abstract

PURPOSE:To joint an artificial bone quickly by providing a porous layer covered with bioactive inorganic material at least on a portion of the surface at contacting side with residual artificial bone. CONSTITUTION:A porous layer 5 covered with bioactive inorganic material 6 is provided on at least a portion of the surface of an artificial bone 1, and corrosion resistant metal or high strength ceramics such as rare metal, stainless steel or titanium alloy is employed as the material for composing the main body of the artificial bone 1. The porous layer 5 is prepared by forming a porous layer containing many holes having diameter in the range of 250-500mum and applying bioactive inorganic material 6 thereon to form a layer having the thickness of 1-100mum. The bioactive inorganic material reacts with bone texture in the body to form strong chemical bond with the artificial bone,and includes appatites, alumina or zirconia ceramics containing appatite, bioglass and the like.

Description

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

[Conventional technology] When bone damage occurs due to an accident, illness, tooth extraction, etc.
Filling of bone defects or voids is required. - In such cases, transplanting living bone from another individual causes immune rejection, so methods have been used to harvest cancellous autologous bone from the patient's own ribs or hip bones and fill the defect. However, this method requires removal of bone tissue other than the damaged area, which increases the number of surgical sites, causes great pain for the patient, and requires a great deal of labor on the part of the doctor.

Moreover, since there are restrictions on the location and amount that can be harvested, it is not always possible to harvest enough bone to compensate for the defect, creating the need for substitute bone.

It goes without saying that such bone substitutes have strength commensurate with the replacement location and are harmless to living organisms, and are quickly and firmly fixed to the autologous bone and will not loosen over long-term use. It won't happen.

For example, artificial hip joint stems are manufactured from corrosion-resistant metals such as stainless steel, Co-Cr alloys, or titanium alloys to ensure stable strength over long periods of time. For example, the following measures have been taken:

(1) Cement fixation: As shown in Fig. 2(a), the supporting part 1a of the substitute bone (hip stem) 1 is placed in the medullary cavity of the autologous bone 2.
is inserted, and the gap between the bone marrow cavity and the supporting portion la of the substitute bone 1 is filled with bone cement 7 made of polymethyl methacrylate or the like and fixed.

(2) Cementless fixation: As shown in Fig. 2(b), the supporting portion 1a of the substitute bone 1 is formed to a thickness that fits tightly into the medullary cavity of the autologous bone 2, and the two are tightly fitted. Fix mechanically.

However, in method (2) as well as in method (1) above, a direct bond between metal and autologous bone is not formed between substitute bone 1 and autologous bone 2, and therefore, after a long period of time, In addition to loosening, method (1) has the problem of adverse effects on living organisms due to polymerization heat of cement and component elution.

In order to solve these problems, research has been conducted to eliminate the cement fixation method and to improve the above-mentioned drawbacks of the cementless fixation method. Examples of such improvement methods include Figures 3(a) and 3(b) and a cross-sectional view of the surface layer (
c) As shown in (d), metal granules 3 or metal fibers 4 are placed on the surface layer of the substitute bone 1 on the side that is in contact with the autologous bone 2.
According to this method, a porous layer 5 is formed on the surface of the substitute bone 1 by arranging the metal fibers 4 so as to be crimped or by arranging knitted, woven, or nonwoven fabrics of metal fibers 4. Osteoblasts growing from the remaining autologous bone invade into the microscopic voids of the porous layer 5, and fixation of the autologous bone 2 and substitute bone 1 is achieved by the anchoring effect of the new bone.

However, with this method, it takes time for new bone to penetrate deep into the porous layer of the substitute bone, and it takes a long time for the substitute bone to be fixed to the autologous bone.

[Problems to be Solved by the Invention] Accordingly, in the present invention, when a substitute bone is applied to compensate for an autologous bone defect, the bone substitute rapidly integrates with the autologous bone, and grows into a strong fixation over time. We investigated bone substitutes that do not loosen even after long-term use.

[Means for Solving the Problems] The present invention was developed to solve the above problems, and the present invention includes a porous layer coated with a bioactive inorganic material on at least a part of the surface in contact with the remaining autologous bone. The main point of the structure is that

[Function] The bone substitute 1 of the present invention is shown in FIG.
c) and cross-sectional views of its surface layer (d), (e), (
As shown in f) and axis), at least a part of the surface is provided with a porous layer 5 coated with a bioactive inorganic material 6, and the biological bone defect part is replaced with the bone substitute 1 of the present invention. When the bioactive inorganic material 6 and the autogenous bone 2 are supplemented with Osteoblasts invade into the bone, and the newly formed bone acts like an anchor to firmly fix the substitute bone 1 and the autologous bone 2. Also, Figure 1 (f) and (g)
When a thick layer of bioactive inorganic material 6 is formed as shown in FIG. Since it penetrates into the back surface of fibers 3 and 4, it exerts an anchoring effect.

The main materials of the bone substitute 1 according to the present invention include precious metals such as gold and silver, stainless steel such as 5US318, and Ti-6
Corrosion-resistant metals such as titanium alloys such as AI-4V, high-strength ceramics such as alumina, zirconia, silicon nitride, etc. can be used, and are formed and applied so as to fit into the shape of the bone defect.

The porous layer 5 coated with the bioactive inorganic material 6 is formed by diffusion bonding a large number of particles 3 made of metal, ceramics, etc. with a particle size of 30G to 800 μm to a part of the surface of the bone substitute 1, or by diffusion bonding a large number of particles 3 made of metal, ceramics, etc. By bending the fibers and arranging them randomly on a part of the surface and performing diffusion bonding, or by arranging a rope, woven fabric, or nonwoven fabric made of fibers on a part of the surface and performing diffusion bonding. Alternatively, a porous layer containing many pores with a pore diameter of 250 to 500 μm is formed by roughening a part of the surface of the base member, and the bioactive inorganic material 6 is further coated thereon to form a layer with a thickness of 1 to 100 μm. is formed. If the pore diameter is less than 250 μm, the invasion of osteoblasts will be insufficient, and if it exceeds 500 μm, it will take time to form new bone generated by the infiltration of osteoblasts, and the anchoring effect will be insufficient. Pore diameter 250~
There is no particular restriction on the means for forming a porous layer having pores of 500 um, but the above-mentioned particle size of 300-um.
The method of diffusion bonding particles 3 of 800 .mu.m or fibers 4 of 100 to 800 .mu.m in diameter as described above can be said to be an advantageous method.

The material for these particles or fibers may be the same as the material for the bone substitute described above, or may be the same as or different from the bone substitute.

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 [Cato (PO2) a (QH) 2], apatite-containing alumina or zirconia ceramics, β-3CaO-P20s, Na2G-CaO-5i
Examples include 02-P205 glass (bioglass), apatite-containing crystallized glass as shown in Table 1, and the like.

Apatite-containing crystallized glass is a composite of crystals and glass, and the size, amount, or composition of the crystals can be changed continuously, and its properties can be changed over a wide range. Further, among bioactive inorganic materials, those that easily elute Ca or phosphoric acid are advantageous because they promote the formation of new bone and are fixed more quickly. The layer made of bioactive inorganic material can be formed on the porous layer by the commonly used thermal spraying method, vapor deposition method, spray pyrolysis method, etc., or by using a sol-gel method to form a sol with adjusted components on the porous layer. It is also possible to form a gel (solid) layer after application. However, the method of forming the bioactive inorganic material layer is not limited at all.

If there is a large difference in coefficient of thermal expansion between the materials constituting the bioactive inorganic material layer and the porous layer, a layer made of a material having a coefficient of thermal expansion intermediate between these materials may be interposed. Naturally, this substance must be harmless, and examples of such substances include glass containing zirconia and ceramics containing zirconia. By providing such an intermediate layer, cracking of the bioactive inorganic material layer and peeling from the porous layer due to a difference in coefficient of thermal expansion can be suppressed. - The substitute bones of the present invention include hip joints, knees, elbows, and shoulders.

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

[Example and Comparative Example] As shown in FIG. 1(a) and its cross-sectional view (d), bone substitute (Ti-6A1-4V titanium alloy hip joint stem) 1
Titanium alloy particles 3 having a diameter of 300 to 800 μm and having the same composition were diffusion bonded to a part of the surface of the sample, and the top was further coated with a bioactive inorganic material (crystallized glass listed in the second column in Table 1) 6. When this was implanted into the femur of a dog, it showed enough bonding to allow walking in 14 days, and no loosening occurred over a long period of time.

It took 28 days for a stem implanted with only a partially porous layer and no bioactive inorganic material layer to form a bond that would allow walking.

[Effects of the Invention] Since the present invention is configured as described above, the substitute bone of the present invention is quickly bonded to the autologous bone and is firmly fixed over time, so that it can be used for a long period of time. No loosening occurs.

[Brief explanation of the drawing]

Figures 1 (21), (b) and (C) are diagrams showing an example of the bone substitute (hip joint stem) according to the present invention, and (d)
. (+4), (f) and (g) are cross-sectional views of the surface layer, Figures 2 (a) and (b) are diagrams showing examples of application of conventional hip joint stems, and Figures 3 (a) and (b). ) and (C
) +' (d) is an example of a conventional bone substitute (hip stem)
FIG. 3 is a sectional view of the surface layer thereof. 1... Substitute bone (hip stem) 2... Autologous bone 3... Granules 4... Fibers 5... Porous layer 6... Bioactive inorganic material 7... Bone cement (a) (b) (c) (a) (b) *Figure 3 March 31, 1988 Patent Application No. 37887 of 1988 2 Alternative name of the invention 3 Relationship with the person making the amendment Case Patent applicant 4. Address of the agent: 407 Shishiko Nicho, 2-3-7 Dojima, Kita-ku, Osaka City (voluntary) 6. Column 7 of “Detailed Description of the Invention” of the specification to be amended, contents of the amendment are correct and incorrect.

Claims (1)

[Claims] (1) A bone substitute for filling a bone defect, characterized in that a porous layer coated with a bioactive inorganic material is provided on at least a portion of the surface in contact with remaining autologous bone.