JPH01223970A - Substitute bone - Google Patents

Abstract

PURPOSE:To form strong bonding to a residual own bone at an early stage and to fix a substitute bone strongly over a long period of time, by providing a porous layer coated with an biologically active inorg. material to the surface of a base member on the contact side with the residual own bone thereof. CONSTITUTION:A porous layer 5 coated with a biologically active inorg. material 6 is provided to a base member 8 and formed so as to be exposed on the contact side with the own bone in such a state that the base member 8 is engaged with a substitute bone main body 1'. When the bone omitted part of a living body is filled with this inventive substitute bone 1, the chemical bonding between the biologically active inorg. material 6 and the own bone 2 is rapidly advanced and, further, an osteoblast penetrates into the fine voids of the porous layer 5 with the elapse of time and the new bone formed therein acts like an anchor to strongly fix the substitute bone 1 and the own bone 2.

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 derived from a separate method would cause an immune rejection reaction, so methods have been taken in which cancellous autologous bone is harvested from the patient's own ribs or hip bones and filled into 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 site and are harmless to living organisms, and they must be able to be quickly and firmly fixed to the autologous bone and not loosen over long-term use. .

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

(1) Cement fixation: As shown in Fig. 3(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 1a 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. 3(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), a direct bond between metal and autologous bone is not formed between substitute bone 1 and autologous bone 2; In addition to loosening over time, method (1) also 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 4(a) and 4(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 took time for new bone to penetrate deep into the porous layer of the substitute bone, and it took 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 that has solved the above problems is a bone substitute for filling a bone defect, in which a base member is fitted into a through hole or a recess formed in the bone substitute. The gist of the structure is that a porous layer coated with a bioactive inorganic material is provided on the surface of the base member that comes into contact with the remaining autologous bone.

[Operation] FIGS. 1(a) to 1(c) are diagrams showing an embodiment of the bone substitute 1 according to the present invention, and FIG. 1(d) is a diagram showing an example of its assembly configuration. As shown in FIG. 1(d), bone substitute 1 of the present invention
is constructed by fitting a base member 8 formed into a shape that fits into the through hole (or recess) into a substitute bone body 1° having a through hole or recess (not shown). The base member 8 is shown in Fig. 1 (e), (f), (g).
As shown in the top view of the surface layer shown in FIG. It is formed so that it appears on the side that comes into contact with the autologous bone when it is fitted into the bone. When a biological bone defect is filled with the substitute bone 1 of the present invention, the bioactive inorganic material 6 and the autologous bone 2
The chemical bond between the two rapidly progresses, and over time, for example, as shown in FIGS. The newly formed bone acts like an anchor and firmly fixes the substitute bone 1 and the autologous bone 2. Also, Figure 1 (g)
, When the layer made of the bioactive inorganic material 6 is formed thickly as shown in (h), the bioactive inorganic material 6 is attached to the autologous bone 2.
The new bone penetrates deeply while chemically bonding with the new bone, and finally the new bone penetrates into the back surface of the granules 3 and fibers 4, so that it exerts an anchoring effect.

The main materials of the substitute bone body 1° according to the present invention include precious metals such as gold and silver, stainless steel such as 5US318, and T.
Corrosion-resistant metals such as titanium alloys such as i-6AI-4V, alumina, and zirconia.

High-strength ceramics such as silicon nitride can be used, and the material is molded to fit the shape of the bone defect.

The main material of the base member 8 can be the same material as that of the above-mentioned substitute bone body 1', and may be the same as or different from the material of the substitute bone body 1'.

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 100 to 800 μm, preferably 300 to 600 μm, to a part of the surface of the base member 8, or Diameter 100-800
By bending fibers of μm and randomly arranging them on a part of the surface and performing diffusion bonding, or by arranging knitted, woven or non-woven fabrics made of fibers on a part of the surface and performing diffusion bonding, etc. Therefore, by roughening a part of the surface of the base member 8, a porous layer containing many pores with a pore diameter of 100 to 500 μm is formed, and the bioactive inorganic material 6 is further coated on top of the porous layer to form a thick layer. A layer with a thickness of 1 to 100 μm is formed. If the pore diameter is less than 100 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 invasion of osteoblasts, and the anchoring effect will be insufficient. Pore diameter 100~500μ
There are no particular restrictions on the means for forming a porous layer having pores of
The most advantageous method is to diffusion-bond particles 3 with a diameter of m or fibers 4 with a diameter of 100 to 800 μm as described above.

As the material for the stiff grains or fibers, the same materials as those for the substitute bone body and base member described above can be used, or the same or different materials as those for the substitute bone body and base member may be used. .

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 + O (PO4)]. a (0)1) 2],
Alumina or zirconia ceramics containing apatite, β-3CaO-P20s, Na20-CaO
-5iO2-P20s glass (bioglass), 1st
Examples include apatite-containing crystallized glass as shown in the table.

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. Examples of such materials 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.

Further, the shape of the substitute bone 1 varies depending on the shape of the autologous bone defect to be compensated. The method of fitting the base member 8 into the through hole or recess of the substitute bone body 1' is not particularly limited, but for example, the following methods (a) to (f) are used. This can be carried out as shown in FIGS. 2(a) to 2(f).

(a) Shrink fit or cold fit.

(b) Tapered fit.

(C) Bolt and nut fastening.

(d) Screw fastening.

(e) Spring stop: substitute bone body 1° or base member 8
A spring-loaded pin is provided on one of the two, and when the two are fitted, the pin will pop out with the force of the spring, fixing the two.

(f) Adhesive fixation An adhesive layer 9 is provided between the second alternative bone body 1° and the base member 8 for fixation. Examples of the adhesive include the above-mentioned polymethyl methacrylate, dental cement, and 4-metal resin.

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] The substitute bone body (Ti-6AI-4■
A base member 8 made of the same composition was fitted onto a titanium alloy hip joint stem body 1" to obtain a substitute bone (hip joint stem) 1 as shown in FIG. 1(a).

Incidentally, on a part of the surface of the base member 8, titanium alloy particles 3 having a diameter of 300 to 600 μm and the same composition as shown in FIG. It had been coated with crystallized glass (2nd crystallized glass 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.

On the other hand, when the stem was implanted with only a porous layer and no bioactive inorganic material layer, it took 28 days 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]

1(a), (b) and (c) are diagrams showing an example of the bone substitute (hip joint stem) according to the present invention, (d) is a diagram showing an example of its assembly configuration, and (e) , (f)
. (g) and (h) are cross-sectional views of the surface layer of the base member;
Figures (a) to (f) are diagrams showing an example of how to fit the substitute bone main body and the base member, Figures 3 (a) and (b) are diagrams showing an example of application of a conventional hip joint stem, and Figure 4 ( Figures a), (b), (c), and (d) are cross-sectional views of an example of a conventional bone substitute (hip stem) and its surface layer. 1...Substitute bone (hip stem) 1°...Substitute bone body (hip stem body) 2...Autologous bone 3...Grain 4...Fiber
5... Porous layer 6... Bioactive inorganic material 7... Bone cement 8... Base member
9... Adhesive layer Figure 1 (a) (b) (°) Figure 2 Figure 3 (a) (b) Figure 4

Claims (1)

[Claims] (1) In a bone substitute for filling a bone defect, a base member is fitted into a through hole or a recess formed in the substitute bone, and a surface of the base member in contact with the remaining autologous bone is provided with a living body. A bone substitute characterized in that it is provided with a porous layer coated with an active inorganic material.