JP2008264562A - Biomaterial for artificial cartilage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biomaterial for artificial cartilage which can be fixed stand-alone to cause no gap in position with ambient organism (bone) tissues and can be directly bound to the ambient organism (bone) tissues in a relatively short time. <P>SOLUTION: The biomaterial for artificial cartilage 10 comprises a core material 1, a biodegradable fixing pin 2 which has a top end projecting from at least one surface of the core material 1, and a bioactive bioceramics powder adhered on the surface of the core material 1, wherein the core material 1 comprises a tissue construct which is triaxial or more, i.e. multi-axial three-dimensional woven or knitted tissue, or their composite tissue of organic fiber. The pin 2 sticks an organism (bone) tissue with the top end to prevent the biomaterial 10 from causing a positional gap or escaping, thereby giving it the early stand-alone property. The bone conductivity (inductivity) of the bioceramics powder adhered on the surface of the core material 1 forms a bone tissue on the surfacial layer in a conductive (inductive) manner so that the core material 1 may bind directly to the organism (bone) tissue. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a biomaterial for artificial cartilage that is expected to be used as an artificial intervertebral disc, an artificial meniscus, or various articular cartilages.

  Conventionally, metals and ceramics have been used as implant materials to be implanted in a living body. However, since these implant materials are hard and difficult to deform, it is difficult to use them as biomaterials for cartilage such as intervertebral discs.

  Although the function is not sufficient at present, clinical trials of Total Disc prostheses stand-alone type artificial discs are commonly It has parts and structure. That is, an artificial intervertebral disk having a so-called sandwich structure in which two metal end plates made of titanium or cobalt-chromium are overlapped on both sides (upper and lower) of a core made of bioinert polyethylene or biocompatible rubber. Yes, the core part moves like a living intervertebral disc by overlapping two polyethylenes, and in the case of rubber, it is imitated by its elasticity. Some of the upper and lower metal plates are treated with hydroxyapatite for the purpose of improving the affinity (bonding) with bone, but the purpose is to prevent slippage when inserted between vertebral bodies. In order to have a self-supporting effect, a structure is adopted in which several corners (one) protrude from the surface of the metal plate and are fixed so as to penetrate into the concave surface of the vertebral body. However, these have the following fatal defects.

(1) First, since it is a sandwich structure of heterogeneous materials of a metal plate and plastic (hard polyethylene plate) or rubber, wear occurs at their interface under repeated driving.
(2) These movements can never be said to be the same as those of natural artificial discs, and suppress natural movements.
(3) The protrusions protruding from the metal plate may damage the upper and lower vertebral bodies, and at the same time, gradually sink and sink into the vertebral bodies under long-term use, which can cause further damage. .
(4) Withdrawal from long-term use or destruction of itself is very likely to cause debris that damages surrounding tissues and nerves.

  In addition to the above, there is an all-metal artificial disc with a spring inside (as an alternative to the core), but it can replace the living body with any material, composition, movement, and durability (corrosion). I can't think of it.

Therefore, the present applicant has developed a biomaterial made of a fiber structure in which organic fibers are made of a multiaxial three-dimensional woven structure or knitted structure having three or more axes, or a composite structure thereof (Patent Document 1). This biomaterial is an excellent one that has both surface chemical biocompatibility and physical biocompatibility at one time. Since it is flexible and deformable like living cartilage and has the ability to withstand repeated loads exceeding millions of times, it is expected to be used as a biomaterial for artificial cartilage.
JP 7-148243 A

  However, the biomaterial made of the fiber structure of Patent Document 1 does not have a self-supporting ability to fix itself to the surrounding living body (bone) tissue in the initial stage of implantation. Therefore, for example, when this is inserted as an artificial intervertebral disc between upper and lower vertebral bodies, it is necessary to fix it so that no positional deviation occurs between the upper and lower vertebral bodies. In other words, a method of fixing the upper and lower vertebral bodies for fixation by fixing them with a metal rod and fixing device conventionally used or a biodegradable absorbable rod and metal fixing device is considered. I had to.

  The present invention has been made to cope with the above-mentioned problems, and the problem to be solved is that it can stand by itself without using any auxiliary fixture for preventing the displacement of the upper and lower vertebral bodies. Providing a biomaterial for artificial cartilage that can be fixed to a living body (bone) tissue so that positional displacement does not occur. Furthermore, an artificial body that can be directly connected to upper and lower living body (bone) tissues in a relatively short period of time. It is to provide a biomaterial for cartilage.

  In order to solve the above problems, the biomaterial for artificial cartilage according to the present invention is at least a core material made of a tissue structure in which organic fibers are multiaxial three-dimensional woven tissue or knitted tissue having three or more axes or a composite tissue thereof. The tip of the biodegradable and absorptive fixing pin protrudes from one side, and bioactive bioceramics powder adheres to the surface of the core material, providing direct binding ability to the bone endplate and initial independence. It is characterized by having shown.

  In the biomaterial for artificial cartilage of the present invention, it is preferable to attach bioceramics powder to the surface of the organic fiber of the surface layer portion having a depth of 2 mm at the maximum from the surface of the core material, It is preferable to perform oxidation treatment of any one of corona discharge, plasma treatment, and hydrogen peroxide treatment.

  In the biomaterial for artificial cartilage of the present invention, two or more fixing pins may be passed through the core material, and both ends of each pin may protrude from both surfaces of the core material. A short fixing pin is embedded in the core material so that its tip protrudes from one side of the core material, and a short fixing pin is embedded inside the opposite surface side of the core material so that its tip protrudes from the opposite surface of the core material. Good. In the latter case, it is preferable to use a short fixing pin with a male screw formed on the outer peripheral surface, and to embed the fixing pin by screwing into one side inside and the other side inside the core material.

  When the self-supporting biomaterial for artificial cartilage of the present invention is inserted between the upper and lower vertebral bodies as, for example, an artificial intervertebral disc, the fixing pin that protrudes from the surface of the core material due to the clamping pressure of the upper and lower vertebral bodies As the biomaterial is fixed between the vertebral bodies by slightly biting into the end plate, which is the contact surface of the vertebral bodies, the position of the vertebral body is not displaced or dislocated. As described above, when the biomaterial for artificial cartilage of the present invention is fixed between vertebral bodies so as not to cause displacement or dislocation, the bioactivity (bone conductivity or bioconductivity of the bioceramics powder adhering to the surface of the core material is determined. Bone tissue is conducted (guided) to the surface of the core material by osteoinductivity, and the core material is directly connected and fixed to the upper and lower vertebral bodies within a relatively short period of time. The core material composed of a multi-axial-three-dimensional woven or knitted tissue or a composite structure of organic fibers made of three or more axes has the same mechanical strength and flexibility as cartilage such as an intervertebral disc. Since it has a relatively easy deformation, it performs the same function as the intervertebral disc with the same behavior as the intervertebral disc. In addition, the fixing pin is disassembled within a relatively short period of time and is absorbed by the living body. However, since the core material is directly coupled to the vertebral body as described above, there is no occurrence of displacement or dislocation.

  In particular, in the biomaterial for artificial cartilage of the present invention, when the bioceramics powder is attached to the surface of the organic fiber in the surface layer portion at a depth of 2 mm at the maximum from the surface of the core material, the living bone tissue is the core material. Since conduction (induction) is formed in a state where it bites into the surface layer portion, the bond becomes strong. When the surface of the core material is subjected to the oxidation treatment, the surface of the core material and the bioceramics powder have better wetting characteristics (wetting characteristics of body fluids), so that invasion and growth of bone cells are promoted. As a result, the core material and the vertebral body are more quickly joined.

  In addition, the biomaterial for artificial cartilage in which two or more fixing pins are penetrated through the core material and both ends of each pin protrude from both sides of the core material not only prevents the lateral displacement but also the biomaterial. There is an advantage that can prevent the rotation. And the core material is fixed to the biomaterial for artificial cartilage in which short fixing pins are embedded inside the one side and the other side of the core material, respectively, and the tip protrudes from the surface opposite to the one side of the core material. There is an advantage that it can be freely compressed and deformed regardless of the use pin. In particular, a short fixing pin is formed with a male screw on the outer peripheral surface, and if the screw is embedded in one side of the core material and inside the opposite surface, the male screw of the fixing pin becomes an organic material of the core material. Because it is entangled with the fiber, even if a force in the direction of pushing in the pin acts, the tip of the pin can bite into the vertebral body etc. without being embedded in the core material, and it can prevent displacement and dislocation, Such a fixing pin having a male screw is advantageous in that it can be easily embedded in the core material simply by screwing in from both sides of the core material.

  The biomaterial of the present invention is made by taking into account all factors and elements such as material, function, durability and affinity (compatibility) of cartilage such as the intervertebral disc of the living body. In addition to the superiority of the core material In addition, the biodegradable absorbable fixing pin for self-supporting prevents displacement and dislocation, and the bioactive bioceramic powder adhered to the surface of the core material fixes it after the absorption of the fixing pin is lost. It is a new and practical biomaterial for artificial cartilage that can maintain stability.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view of a biomaterial for artificial cartilage according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG.

  The biomaterial 10 for artificial cartilage is formed in a bulk shape having a substantially front and rear circular plane shape in which a rectangle and a semicircle are combined as shown in FIG. 1, and is used as an artificial disc as shown in FIG. It is.

  As shown in FIGS. 1 and 2, this biomaterial 10 is formed by passing three biodegradable and absorptive fixing pins 2 through a bulk core material 1 having a substantially front-rear circular planar shape, The pin 2 has a structure in which both ends of the pin 2 protrude from both surfaces of the core material 1.

  The core material 1 is composed of a tissue structure in which an organic fiber is a three-dimensional woven structure or a knitted structure or a composite structure thereof, and has mechanical strength and flexibility comparable to cartilage such as an intervertebral disc, The deformation is extremely biomimetic.

  The tissue structure of the core material 1 is similar to the tissue structure described in Japanese Patent Application No. 6-254515 (Japanese Patent Laid-Open No. 7-148243) already filed by the present applicant, and its geometrical structure. When the shape is represented by the number of dimensions and the orientation number of the fiber array is represented by the number of axes, a structure composed of a multi-axis-three-dimensional structure having three or more axes is preferably employed.

  The three-axis-three-dimensional structure is a three-dimensional structure of fibers in three vertical, horizontal, and vertical directions. A typical shape of the structure is a thick bulk like the core material 1 described above. The shape (plate shape or block shape) may be a cylindrical shape or a honeycomb shape. This three-axis-three-dimensional structure is classified into an orthogonal structure, a non-orthogonal structure, an entangled structure, a cylindrical structure, and the like depending on the structure. In addition, a multi-axis-three-dimensional structure having four or more axes has a strength isotropy of the structure by arranging multi-axis orientations such as 4, 5, 6, 7, 9, and 11 axes. It can be improved. And by these selections, the more biomimetic core material 1 more closely resembling a living cartilage tissue can be obtained.

  It is preferable that the internal porosity of the core material 1 made of the above-described tissue structure is in the range of 20 to 90%. When the ratio is less than 20%, the core material 1 becomes dense and the flexibility and deformability are impaired. Therefore, the core material is unsatisfactory as a core material for artificial cartilage. Since the compressive strength and shape retention of No. 1 are reduced, it is also unsuitable as a core material for biomaterials for artificial cartilage.

  The organic fiber constituting the core material 1 is a bioinert synthetic resin fiber, for example, a fiber such as polyethylene, polypropylene, polytetrafluoroethylene, or an organic core fiber covered with the above bioinert resin. For example, coated fibers that are bioinactive are preferably used. In particular, a coated fiber having a diameter of about 0.2 to 0.5 mm obtained by coating a core fiber (twisted yarn) of ultrahigh molecular polyethylene with a linear low-density polyethylene film has strength, hardness, elasticity, and knitting. It is the most suitable fiber in terms of ease of handling. In addition, fibers having bioactivity (for example, having bone conduction or induction ability) can be selected.

  In addition, since the structure structure which comprises the core material 1 is disclosed in detail in said Japanese Patent Application No. 6-254515, the further description is abbreviate | omitted.

  A bioactive bioceramic powder is adhered to the surface of the core material 1. When bioceramic powder is attached in this way, bone tissue is conducted (induced) to the surface layer portion of the core material 1 in a relatively short period of time due to its bioactivity (bone conduction ability or osteoinduction ability), There is an advantage that the core material 1 is directly bonded and fixed to the living bone tissue. The bioceramic powder is a surface layer having a depth of about 1 to 2 mm from the surface of the core material 1 (in other words, a depth of at most 2 mm from the surface of the core material 1) so that the voids of the core material 1 are not filled. It is preferable to make it adhere to the surface of the organic fiber of a part, and when it does in this way, a biological bone tissue will come to be strongly joined in the state which digged into the surface layer part of core material 1.

  Bioceramic powders are bioactive, have good osteoconductivity or osteoinductive ability, and good biocompatibility. Uncalcined and unfired hydroxyapatite, dicalcium phosphate, tricalcium phosphate, tetracalcium Powders such as phosphate, octacalcium phosphate, calcite, serabital, diopsite, and smallpox are used. And what adhered the alkaline inorganic compound and the basic organic substance to the surface of these powders can also be used. Among these, bioresorbable bioceramic powders that are totally resorbed in vivo and completely replaced with bone tissue are preferable. In particular, uncalcined and unfired hydroxyapatite, tricalcium phosphate, octacalcium Phosphate is optimal because it has extremely high activity, is excellent in osteoconductivity or osteoinductivity, has low toxicity, and is absorbed into the living body in a short period of time. Those bioceramic powders having a particle diameter of 10 μm or less are used, and those having a particle diameter of about 0.2 to 5 μm are particularly suitable.

  Further, it is preferable to subject the surface of the core material 1 to oxidation treatment such as corona discharge, plasma treatment, hydrogen peroxide treatment, etc., and in this way, wetting characteristics of the surface of the core material 1 and the attached bioceramic powder. Since (wetting property of body fluid) is improved, the invasion and growth of bone cells into the surface layer portion of the core material 1 are promoted, and the core material and the vertebral body and the like are more quickly joined.

  The fixing pin 2 penetrates the core material 1 described above, and both ends thereof protrude from both surfaces of the core material 1. With such a fixing pin 2, when the biomaterial 10 is inserted between the upper and lower vertebral bodies 3, 3 as shown in FIG. Since both ends of the fixing pin 2 projecting from both surfaces bite into the contact surfaces of the vertebral bodies 3 and 3, the biomaterial 10 is not fixed between the vertebral bodies and no displacement occurs.

  The number of the fixing pins 2 is preferably two or more, and in the case of one, there is a disadvantage that even if the lateral displacement of the biomaterial 10 can be prevented, the rotation of the biomaterial 10 cannot be prevented. However, if the biomaterial 10 can be mounted so as not to rotate, the number may be one. The most preferable number of the fixing pins 2 is three as shown in the figure. In this case, there is an advantage that the fixing pins 2 can be mounted between the upper and lower vertebral bodies 3 and 3 stably by supporting three points. Needless to say, the number may be four or more.

  It is desirable to form both ends of the fixing pin 2 in a pointed shape, for example, a conical shape as shown in the figure. If such a shape is used, the upper and lower vertebral bodies 3 and 3 are well bitten and the fixing strength is improved.

  Moreover, it is preferable that the protruding dimensions of both ends of the fixing pin 2 be about 0.3 to 2 mm, and if it is less than 0.3 mm, the biting of the both ends of the pin 2 is insufficient and the fixing strength of the biomaterial 10 On the other hand, when it exceeds 2 mm, the two tips of the pin 2 are not easily bite into the upper and lower vertebral bodies 3, 3, and a gap is likely to be generated between the core material 1 and the vertebral bodies 4, 4. Adhesion decreases.

  Initially, when the biomaterial 10 is inserted between the vertebral bodies 3, 3, a large pinching force is applied to the fixing pin 2 from the upper and lower vertebral bodies 3, 3. Therefore, it is desirable that the fixing pin 2 is made using a biodegradable absorbent polymer such as crystalline polylactic acid or polyglycolic acid having a viscosity average molecular weight of 150,000 or more, preferably about 200,000 to 600,000. It is also desirable to use a reinforced composite (composite) in which a bioactive bioceramic powder is mixed with these polymers. Further, the strength may be improved by orienting polymer molecules by a method such as compression molding, forging molding, or stretching, if necessary.

  The diameter of the pin 2 is preferably about 1 to 3 mm in order to ensure the strength. If the pin 2 is thinner than 1 mm, the pin 2 may be broken, and if it is thicker than 3 mm, the time required for decomposition and absorption becomes longer. The lengths of the pins 2 do not have to be the same, and the length may be adjusted by cutting so that self-supporting is most effective during the operation in accordance with the concave shape of the vertebral body 3.

  When the artificial cartilage biomaterial 10 having the above-described configuration is mounted between the upper and lower vertebral bodies 3 and 3 as an artificial intervertebral disc as shown in FIG. Since both ends of the pin 2 for bite bite into the contact surface of the vertebral bodies 3 and 3, the biomaterial 10 is fixed between the vertebral bodies 3 and 3 so that positional displacement and dislocation do not occur. Accordingly, it is not necessary to fix the biomaterial using an auxiliary fixture or the like, and thus surgery can be easily performed. When the biomaterial 10 is mounted between the vertebral bodies 3 and 3 in this manner, the bone conduction ability or the osteoinductive ability of the bioactive bioceramic powder adhered to the surface of the core material 1 makes the bone within a relatively short period of time. The tissue is conducted (induced) in the surface layer portion of the core material 1, and the core material 1 is directly coupled to the upper and lower vertebral bodies 3 and 3 and fixed. However, since the core material 1 is made of organic fibers, the bone tissue does not enter the core material. Moreover, the core material 1 made of the tissue structure of organic fibers has mechanical strength and flexibility comparable to cartilage such as an intervertebral disc as described above, and is relatively easy to deform. It can play the role of an intervertebral disc by taking the same behavior as an intervertebral disc. The fixing pin 2 is disassembled and finally absorbed by the living body. Even if the fixing pin 2 is disassembled and absorbed, the core material 1 is directly coupled to the vertebral bodies 3 and 3, so There will be no slippage or slippage.

  In the biomaterial 10 of the above-described embodiment, both ends of the fixing pin 2 are protruded from both surfaces of the core material 1, but one end of the fixing pin 2 may be protruded from one surface of the core material 1. . Since one side of the biomaterial having such a configuration can be fixed to one vertebral body 4 by the fixing pin 2, the fixing strength is lowered, but the biomaterial can be prevented from being displaced or dislocated. In short, it is only necessary to achieve the purpose in which the biomaterial has an initial fixation property and exists independently between the vertebral bodies without slipping off.

  Alternatively, the core material 1 may be divided into left and right parts, two fixing pins may be inserted through each core material half, and both ends of each pin 2 may protrude from both sides of the core material half. Good. The biomaterial for artificial cartilage of the present invention can be divided and manufactured in this way, and such a bipartite type biomaterial for artificial cartilage is partially substituted for a case where a total replacement type is unnecessary. Either one of the biomaterials can be used. Further, if the biomaterial of the three-part type is used, partial replacement can be performed for a case where only the central part of the cartilage is damaged or a case where one or both of the side parts are damaged. Needless to say, a cartilage partially damaged case may be arbitrarily shaped without being limited to the above-described two-divided type or three-divided type.

  FIG. 4 is a sectional view of a biomaterial for artificial cartilage according to still another embodiment of the present invention.

  This biomaterial 11 for artificial cartilage uses, as a fixing pin, a short fixing pin 2a having a male screw formed on the outer peripheral surface and having both ends sharpened conically and having no head, and this fixing pin 2a 3 are screwed into the inner side of the core material 1 (inside the upper surface side) and embedded, and the pointed tip of one side protrudes from one side of the core material 1 and the inner side on the opposite side of the core material 1 (inner side on the lower surface side) ), Three fixing pins 2a are screwed in and embedded, and one pointed tip is protruded from the opposite surface of the core material 1. Since the material of the fixing pin 2b and the core material 1 are the same as those of the fixing pin 2 and the core material 1 described above, description thereof is omitted.

  In such a biomaterial 11, since the male screw of the short fixing pin 2a is entangled with the organic fiber of the core material 1, the pin 2a is buried in the core material 1 even if a force in the direction of pushing the pin 2a is applied. Never do. Therefore, when this biomaterial 11 is inserted between the vertebral bodies 3 and 3 as an artificial intervertebral disc, the tip of the pin 2a bites into the end plate of the vertebral bodies 3 and 3 without being embedded in the core material 1, Misalignment / reversion of the material 11 is prevented. Since the fixing pin 2a does not interfere with the compressive deformation of the core material 1 when the core material 1 is compressed and deformed from above and below by the vertebral bodies 3 and 3, the core material 1 is not restrained by the fixing pin 2a. It can freely compress and deform to serve as an intervertebral disc. Further, when the fixing pin 2a having such a male screw is used, there is an advantage that it can be easily embedded in the core material 1 simply by screwing from both sides of the core material 1.

  The biomaterial 11 may also be a two-part type or a three-part type, as described above, so that partial replacement can be performed for cases that do not require a total replacement type. In addition, instead of the fixing pin 2a, a short fixing pin having a head is used, and the head of each pin is disposed on one side (upper side inside) of the core material 1 and on the opposite side (lower side). It is also possible to embed each of the pins in such a manner that the tips of the pins protrude from both sides of the core material 1. Also in this case, since the head of each pin is embedded in the core material 1 and the tip of each pin does not immerse, the tip of each pin can securely bite into the vertebral bodies 3 and 3 to fix the biomaterial, Moreover, since each pin does not prevent the compressive deformation of the core material 1, the core material 1 can be freely compressed and deformed.

  As described above, the present invention has been described by taking the biomaterials 10 and 11 for artificial cartilage that can be used as an artificial intervertebral disc as an example. Of course, it also includes a biomaterial for artificial cartilage that can be used as articular cartilage.

It is a perspective view of the biomaterial for artificial cartilage which concerns on one Embodiment of this invention. It is the sectional view on the AA line of FIG. It is explanatory drawing of the use condition of the biomaterial for artificial cartilage. It is sectional drawing of the biomaterial for artificial cartilage which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core material 2 Fixing pin 2a Short fixing pin 3 Vertebral body 10,11 Biomaterial for artificial cartilage

Claims (8)

  The tip of the biodegradable and absorptive fixing pin protrudes from at least one side of a core material made of a tissue structure composed of a multiaxial three-dimensional or three-dimensional woven or knitted structure or a composite structure of these organic fibers. A biomaterial for artificial cartilage, characterized in that a bioactive bioceramic powder is attached to the surface of a core material, and has a direct binding ability and initial self-supporting property to a bone end plate.   The biomaterial for artificial cartilage according to claim 1, wherein a bioceramic powder is adhered to the surface of the organic fiber in the surface layer portion having a depth of 2 mm at the maximum from the surface of the core material.   The bioceramic powder is any one of uncalcined, uncalcined hydroxyapatite, dicalcium phosphate, tricalcium phosphate, tetracalcium phosphate, octacalcium phosphate, calcite, serabital, diopsite, and natural cocoon. The biomaterial for artificial cartilage according to claim 1 or 2.   The biomaterial for artificial cartilage according to any one of claims 1 to 3, wherein the surface of the core material is oxidized by any one of corona discharge, plasma treatment, and hydrogen peroxide treatment.   The biomaterial for artificial cartilage according to any one of claims 1 to 4, wherein two or more fixing pins are passed through the core material, and both ends of each pin protrude from both surfaces of the core material.   A short fixing pin is embedded inside one side of the core material and its tip protrudes from one side of the core material, and a short fixing pin is embedded inside the opposite surface side of the core material and its tip is opposite to the core material. The biomaterial for artificial cartilage according to any one of claims 1 to 4, wherein the biomaterial for artificial cartilage is protruded from a surface.   The biomaterial for artificial cartilage according to claim 6, wherein the short fixing pin has a male screw formed on its outer peripheral surface, and is screwed and embedded in the inside of one side and the opposite side of the core material.   8. The fixing pin is made of any one of biodegradable and absorbable polylactic acid, polyglycolic acid, or a composite of polylactic acid and bioceramic powder. Biomaterial for artificial cartilage.

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