JP5995730B2 - Bone fixation screw - Google Patents

Description

  The present invention relates to a living bone fixing screw, and more specifically, stress shielding and metal allergy can be avoided and are not easily damaged. The present invention relates to a living bone fixing screw.

  As a method for embedding or fixing a living bone, an artificial tooth (also referred to as a denture) or an artificial joint in a defect or a joint of a bone or a tooth (hereinafter sometimes referred to as a living bone), A method is known in which a living bone fixing screw (including an artificial tooth root) or the like is screwed into a prepared pilot hole.

  As such a living bone fixing screw, a non-metallic material such as a metal or a ceramic material may be used (for example, Patent Documents 1 to 4). For example, Patent Document 3 generally describes "artificial tooth root having a double structure of an outer cylinder and an inner tooth root made of metal or ceramic, and the outer cylinder and the inner tooth root are fixed by a cushioning material". 4 includes an outline “a receiving member whose outer peripheral surface is covered with a bioactive layer, an artificial tooth root body inserted into a recess of the receiving member, and an impact mitigating member interposed between the artificial tooth root body and the receiving member. And an artificial tooth root in which an artificial tooth root body and a receiving member are integrally coupled via an impact reducing member.

  In addition, as a living bone fixing screw, a living bone fixing screw made of a material having a mechanical characteristic very similar to that of a living bone, for example, engineering plastic is also known. For example, a porous bone fixing screw made of an implantable polymer such as polyetheretherketone (PEEK) (Patent Document 5 etc.), a plastic that transmits X-rays, such as PEEK Producing a screw shank (Patent Document 6) has been proposed.

  In addition, although it is not a living bone fixing screw itself, a “surface foam having a substantial part and a surface layer” (Patent Document 7) that can be generally used as a living body implant is also generally described as “on the outermost surface”. A "biological implant provided with a dense substantial part having an uneven structure and a porous surface layer" (Patent Document 8) is known. Furthermore, a medical material or the like is known that is wound around a living bone fixing screw, for example, to fix an artificial tooth root to a bone tissue (for example, Patent Document 9).

JP 2005-329244 A Special table 2007-531555 gazette Japanese Patent No. 2547953 Japanese Patent Publication No.7-12365 Special table 2012-511334 gazette Special table 2012-511980 gazette International Publication No. 2009/095960 Pamphlet JP 2010-253195 A JP 2010-233860 A

  In addition to the possibility of causing metal allergy and the like when using metal as the material for the bone fixing screw, the bone and metal Due to the difference in mechanical properties, stress shielding occurs (stress shielding), and the surrounding bone may be absorbed and become brittle. In addition, when a ceramic material having a low strength and a high elastic modulus is used as the material for the living bone fixing screw, there is a problem that the living bone fixing screw is particularly susceptible to damage because it is subjected to a large load.

  By the way, such a living bone fixing screw is screwed into a pilot hole formed in the bone, that is, screwed and implanted, so that the living bone fixing screw is loaded with a load acting when the living bone fixing screw is screwed. In order to prevent breakage, it is preferable that the living bone fixing screw is quickly inserted into the prepared hole so that the bone in which the prepared hole is formed is not damaged or necrotized. However, when it is intended to ensure the implantability in the living bone fixing screw, the screwed state or the coupled state between the living bone fixing screw once implanted in the prepared hole and the bone in which the prepared hole and the prepared hole are formed. There is a problem that the fixation state (referred to as initial fixation) when the bone fixing screw is embedded is lowered. As described above, it is desired that the living bone fixing screw has both embedding property and initial fixing property, which are mutually contradictory characteristics.

  It goes without saying that such a living bone fixing screw should also exhibit a bone-binding ability to be firmly bonded to the bone from the viewpoint of reducing the burden on the patient, the recovery state, and the like. In particular, when a large load is applied to the living bone fixing screw after implantation, for example, in the case of an artificial tooth root that is subjected to a meshing pressure, a chewing force, etc., the fixing state when the living bone fixing screw is embedded is kept for a long time. It is also desirable to maintain it over time.

  Therefore, the present invention provides a living bone fixing screw that can avoid stress shielding and metal allergy, is difficult to break, has both opposing embedding properties and initial fixing properties, and also exhibits high bone bonding properties. The purpose is to do.

  The inventors of the present invention have made extensive studies on the bone fixing screw, and as a result, the surface porous layer is integrally formed of the same biocompatible polymer as the substantial part having the screw base on which the thread base is formed, and If the thickness of the surface porous layer formed on the valley bottom of the screw base and the surface porous layer formed on the valley bottom and the altitude difference between the thread base adjacent to the valley bottom are set within a specific range, stress shielding and metal allergy are reduced. In addition to being able to produce a bone-fixing screw that can be avoided and is not easily damaged, the produced bone-fixing screw can be compatible with both the embedding property and the initial fixing property, and exhibit high bone-binding properties. And the present invention was completed.

  Therefore, the living bone fixing screw according to the present invention has a substantial portion having a screw base portion formed with a screw base portion that rotates at least once on a peripheral side surface, and the same biocompatibility as the substantial portion at least on the bottom of the screw base portion. A surface porous layer integrally formed of a polymer, and the surface porous layer formed at the bottom of the valley has a thickness of at least a part of 50 to 500 μm, and the thread adjacent to the bottom of the valley. It has a height difference of 200 to 800 μm with respect to the base.

  The screw for fixing a living bone according to the present invention comprises a substantial portion having a screw base portion formed with a screw base portion that rotates at least once on a peripheral side surface, and the same biocompatible polymer as the substantial portion at least at the bottom of the screw base portion. The surface porous layer formed on the bottom of the valley has a thickness of at least a part of 50 to 500 μm, and is formed on the base of the thread adjacent to the bottom of the valley. On the other hand, since it has an altitude difference of 200 to 800 μm, stress shielding and metal allergy can be avoided, it is difficult to break, it has both the embedding property and the initial fixation property that are mutually contradictory, and also has high bone bondability. Demonstrate.

FIG. 1 is a schematic view showing a living bone fixing screw which is an example of a living bone fixing screw according to the present invention. FIG. 2 is a schematic enlarged cross-sectional view showing a screw portion of a living bone fixing screw which is an example of a living bone fixing screw according to the present invention. FIG. 3 is a schematic enlarged cross-sectional view showing a surface porous layer of a living bone fixing screw which is an example of the living bone fixing screw according to the present invention. FIG. 4 is a schematic view showing a living bone fixing screw which is another example of the living bone fixing screw according to the present invention. FIG. 5 is a schematic view showing a living bone fixing screw which is still another example of the living bone fixing screw according to the present invention. FIG. 6 is an enlarged photograph of the screw part of the living bone fixing screw manufactured in Example 2-1 observed with a scanning electron microscope. FIG. 6A shows the screw part observed at a magnification of 30 times. FIG. 6B is a cross-sectional enlarged photograph when the cut surface is observed at a magnification of 100 times when cut along a plane including the axis of the screw portion. FIG. 7 is an enlarged photograph in which the thread of the living bone fixing screw manufactured in Example 2-1 was observed with a scanning electron microscope, and FIG. 7A was observed at a magnification of 300 times. FIG. 7 (b) is an enlarged photograph when the thread is observed at an enlargement ratio of 3000 times. FIG. 8 is an enlarged photograph in which the thread groove of the living bone fixing screw manufactured in Example 2-1 was observed with a scanning electron microscope, and FIG. 8A was observed at a magnification of 300 times. FIG. 8 (b) is an enlarged photograph when the thread groove is observed at an enlargement ratio of 3000 times. FIG. 9 is an enlarged photograph in which the screw thread was observed with a scanning electron microscope after being removed from the pilot hole once screwed with the living bone fixing screw produced in Example 2-1, and FIG. FIG. 9B is an enlarged photograph when the mountain is observed at an enlargement ratio of 10000, and FIG. 9B is an enlarged photograph when the screw thread is observed at an enlargement ratio of 10,000.

  A living bone fixing screw according to the present invention will be specifically described with reference to the drawings. As shown in FIG. 1, a living bone fixing screw 1, which is an example of a living bone fixing screw according to the present invention, includes a head portion 11, a cylindrical portion 12, and a screw portion 13 that are sequentially arranged along the axial direction. And have.

  The head 11 is formed with a slit (not shown in FIG. 1) and the like that engages with a tool for screwing the living bone fixing screw 1 on its end face. When the living bone fixing screw is used as a dental living bone fixing screw (also referred to as an artificial tooth root) for fixing the artificial tooth to the alveolar bone, the head 11 is artificially provided on the end surface after implantation. Teeth are installed. The cylindrical portion 12 is connected to the end surface of the head 11 opposite to the end surface where the slit is formed, and connects the head 11 to a screw portion 13 described later. The screw portion 13 is connected to the end surface of the cylindrical portion 12 opposite to the head portion 11, and is connected to the complete screw portion 14 having the thread 17 and the screw groove 18 and to the opposite side of the complete screw portion 14 to the cylindrical portion 12. And a screw tip 15. The complete screw portion 14 has a so-called “triangular screw” tooth shape, and is set to a lead and a pitch that form a so-called “single screw”. Various dimensions such as the axial length, the outer diameter, the valley diameter, the pitch, the lead, the angle of the screw thread 17 and the height of the screw thread 17 of the complete screw portion 14 are determined depending on the portion to be implanted, the shape, the dimension, and the like. Accordingly, it is set appropriately. The outer diameter of the complete screw portion 14 is appropriately set according to the inner diameter of the pilot hole provided in the site to be implanted, and is, for example, 400 to 700 μm larger than the inner diameter of the pilot hole. When used as a tooth root, it is set larger by 500 to 600 μm. An example of the outer diameter of the complete screw portion 14 is 3 to 12 mm, and particularly 3 to 8 mm when the living bone fixing screw 1 is used as an artificial tooth root.

  As shown clearly in FIG. 2, such a living bone fixing screw 1 is dense and has a substantial part 5 which is a base of the living bone fixing screw 1 and the same biocompatible as the substantial part 5 on the surface of the substantial part 5. And a surface porous layer 6 integrally formed of a conductive polymer. Thus, when the substantial part 5 and the surface porous layer 6 are formed of a biocompatible polymer, stress shielding and metal allergy can be avoided and it is difficult to break. When the substantial portion 5 and the surface porous layer 6 are integrally formed of the same biocompatible polymer, that is, without having an adhesive layer between the substantial portion 5 and the surface porous layer 6, the substantial portion. When the surface porous layer 6 is directly connected to 5, the strength of the living bone fixing screw 1 is improved and it is more difficult to break.

  Since the substantial part 5 serves as a base for the living bone fixing screw 1, the head part 11 and the cylindrical part 12 are formed basically in the same manner as the living bone fixing screw 1, and are sequentially provided along the axial direction. And a screw base portion 21 that becomes a base portion of the screw portion 13 covered with the surface porous layer 6. Therefore, the surface porous layer 6 is not necessarily arranged on the head portion 11 and the cylindrical portion 12, and the surface porous layer 6 is provided on the entire surface of the screw base portion 21, that is, the entire surface of the screw thread base portion 23 and at least the valley bottom 25. Has been placed. FIG. 2 shows a part of the screw base 21 that is the base of the complete screw portion 14.

  The screw base portion 21 includes a base portion of the complete screw portion 14 and a base portion of the screw tip 15, and is provided between one screw base portion 23 that rotates at least once on the peripheral side surface of the base portion of the complete screw portion 14 and the adjacent screw base portion 23. And a thread groove base 24 formed on the surface. The thread base 23 is preferably arranged so as to rotate a plurality of times in a spiral shape, and is preferably three or more rotations in view of high initial fixability. The upper limit of the rotational speed is appropriately determined according to the axial length, pitch, and the like of the complete screw portion 14, and is particularly preferably, for example, 5 rotations or more, and is 15 rotations or less considering the embedding property. It is preferable that it is 12 rotations or less. In the living bone fixing screw 1, the screw thread base 23 is arranged to rotate seven times. Between two adjacent flanks of the adjacent thread base 23, that is, the thread groove base 24 has a valley bottom 25 connecting the two flank facing each other, and this valley bottom has a flat bottom surface or curved surface. . When the flat bottom surface or curved surface is present in the thread groove base 24 in this way, the surface porous layer 6 into which the biological tissue can invade can be arranged in a wider range, so that a large amount of biological tissue enters the surface porous layer 6 and is high. Bone binding can be exerted.

  Various dimensions such as the axial length of the screw base 21, the lead, and the angle of the screw base 23 are appropriately set, but the pitch, outer diameter, valley diameter, and height of the screw base 23 are as follows. Preferably it is set. The pitch of the thread base 23 is preferably 300 to 1500 μm in that a flat bottom surface or a curved valley bottom 25 can be formed. The outer diameter of the screw base portion 21 is appropriately set in consideration of the thickness of the surface porous layer 6 so that the outer diameter of the complete screw portion 14 is within the above range, for example, 2.8 to 11.9 mm, In particular, in the case of an artificial tooth root, it is preferably 2.8 to 7.9 mm, and the height of the thread base 23 is 300 to 3000 μm, and in the case of an artificial tooth root, it is preferably 300 to 2000 μm. If the height of the thread base portion 23 is within the above range, even if the surface porous layer 6 is formed by the method described later, the complete thread portion 14 can be formed without impairing the profile of the thread base portion 23, and the embedding property can be improved. In addition, both initial fixability can be achieved. The outer diameter of the screw base 21 and the diameter of the valley are set in an appropriate range in consideration of the outer diameter and the height of the screw base 23 according to the part to be implanted.

  The substantial part 5 is made of a biocompatible polymer and is entirely solid. The biocompatible polymer preferably has mechanical properties that are similar or similar to living bone. Therefore, the substantial part 3 also has a mechanical characteristic similar to or close to that of a living bone like the biocompatible polymer. Examples of mechanical properties that are similar to or approximate to a living bone include an elastic modulus of 1 to 50 GPa and a bending strength of 100 MPa or more, and the biocompatible polymer may have at least one of these properties.

  Examples of such biocompatible polymers include biocompatible polymers in which fibers are not mixed (also referred to as fiber-free biocompatible polymers), fiber-reinforced biocompatible polymers in which fibers are mixed, and the like. . Examples of the fiber-free biocompatible polymer include polyamide, polyacetal, polycarbonate, polyphenylene ether, modified polyphenylene ether, polyester, polyphenylin oxide, polybutylene terephthalate, polyethylene terephthalate, polysulfone, syndiotactic polystyrene, polyethersulfone, Engineering such as polyphenylene sulfide, polyarylate, polyetherimide, polyetheretherketone, polyamideimide, polyimide, fluorine resin, ethylene vinyl alcohol copolymer, polymethylpentene, diallyl phthalate resin, polyoxymethylene, polytetrafluoroethylene Examples include plastic.

  Examples of the biocompatible polymer that becomes the matrix of the fiber reinforced biocompatible polymer include, for example, polyethylene, polyvinyl chloride, polypropylene, EVA resin, EEA resin, 4-methylpentene-1 resin, and ABS resin in addition to the engineering plastics. AS resin, ACS resin, methyl methacrylate resin, ethylene vinyl chloride copolymer, propylene vinyl chloride copolymer, vinylidene chloride resin, polyvinyl alcohol, polyvinyl formal, polyvinylacetoacetal, polyfluorinated ethylene propylene, polytrifluoride Examples include ethylene chloride, methacrylic resin, noryl resin, polyallyl ether ketone, polyketone sulfide, polystyrene, isophthalic acid resin, polyurethane, alkylbenzene resin, polydiphenyl ether, etc. That.

  Examples of the fibers contained in the fiber reinforced biocompatible polymer include carbon fibers including carbon nanotubes, glass fibers, ceramic fibers, metal fibers, and organic fibers. Examples of the glass fibers include fibrous materials of borosilicate glass (E glass), fibrous materials of high strength glass (S glass), fibrous materials of high elasticity glass (YM-31A glass), and the like. Examples of the ceramic fiber include a silicon carbide fiber, a silicon nitride fiber, an alumina fiber, a potassium titanate fiber, a boron carbide fiber, a magnesium oxide fiber, Examples include zinc oxide fibrous materials, aluminum borate fibrous materials, boron fibrous materials, etc. Examples of the metal fibers include tungsten fibrous materials, molybdenum fibrous materials, and stainless steel fibrous materials. Steel fiber, tantalum fiber, and the like. Examples of the organic fiber include, for example, polyvinyl alcohol fiber, polyamide fiber, polyethylene, and the like. Fibrous material terephthalate, fibrous material of a polyester, a fibrous material aramid, and the like. The fiber can be used alone or in a mixture of two or more.

  Among these, polyether ether ketone (PEEK) having high strength and low elasticity, close to mechanical bones, and high biocompatibility is particularly preferable as the biocompatible polymer.

  In addition to the biocompatible polymer, the substantial part 5 includes an antistatic agent, an antioxidant, a light stabilizer such as a hindered amine compound, a lubricant, an antiblocking agent, an ultraviolet absorber, an inorganic filler, and a pigment as necessary. It may contain various additives such as coloring agents.

  The surface porous layer 6 only needs to be disposed on at least a part of the valley bottom 25 of the screw base 21. In the living bone fixing screw 1, the entire surface of the screw base 21 is made of the same biocompatible polymer as the substantial part 5. It is integrally formed. Thus, when the surface porous layer 6 is integrally disposed on the valley bottom 25, the living bone fixing screw 1 exhibits high bone connectivity, and is excellent in reducing the burden on the patient and recovering from the patient. The fixed state when the fixing screw 1 is embedded can be maintained over a long period of time. And when the surface porous layer 6 is arrange | positioned in the surface of the thread base 23, in addition to the valley bottom 25, ie, a flank and the top, in addition to the said effect, a living bone without damaging a pilot hole and the adjacent bone tissue The fixing screw 1 can be screwed into the prepared hole, and the fitting property of the screwed living bone fixing screw 1 with respect to the prepared hole is improved, so that even higher initial fixing property is exhibited. Further, once screwed into the pilot hole, the surface porous layer 6 acts on the living bone fixing screw 1, for example, exerts a buffer function to disperse and relieve stress at the time of meshing, etc. While effectively preventing damage to the bone hole in the pilot hole or in the vicinity, the fixed state when the living bone fixing screw 1 is embedded is maintained for a longer period of time and is less likely to fall off. Furthermore, if the surface porous layer 6 is also disposed on the surface of the thread base 23, the bone bonding property of the surface porous layer 6a disposed on the valley bottom 25 can be supplemented.

  The surface porous layer 6 is integrally formed of the same biocompatible polymer as that of the substantial part 5, and is preferably formed of PEEK.

  The surface porous layer 6 is formed to have an appropriate thickness depending on the portion to be implanted, but at least one of the surface porous layer 6a formed on the valley bottom 25, that is, the surface porous layer 6a formed on the valley bottom 25. The part has a thickness of 50 to 500 μm. If the thickness is less than 50 μm, the amount of living tissue entering the surface porous layer 6a may be reduced, and high bone-binding property may not be exhibited. When the screw is screwed into the surface, the surface porous layer 6a may be damaged or fallen, and the bone-binding property may be deteriorated. Also, the substantial part 5 may have a small diameter, and the strength required for the bone fixing screw 1 may not be exhibited. is there. The thickness of the surface porous layer 6a formed on the valley bottom 25 is more preferably 70 to 450 [mu] m, and particularly preferably 100 to 400 [mu] m, from the viewpoint of achieving both bone bonding and strength. The surface porous layer 6a having a thickness of 50 to 500 μm is formed on a part of the valley bottom 25. In other words, a part of the surface porous layer 6a formed on the valley bottom 25 has a thickness of 50 to 500 μm. . The surface porous layer 6 a having a thickness of 50 to 500 μm is preferably formed on a valley bottom 25 sandwiched between two adjacent thread bases 23, and preferably has a valley bottom 25 sandwiched between two thread bases 23. It is preferable that it is formed in half or more with respect to the full length, and in this example, it is formed in the whole valley bottom 25 sandwiched between two screw bases 23.

  On the other hand, the surface porous layer 6b formed on the side surface of the thread base 23, that is, the flank and the top, preferably has a thickness of 10 to 200 μm, and particularly preferably has a thickness of 20 to 180 μm. preferable. When the surface porous layer 6b has a thickness in the above range, the living bone fixing screw 1 can be screwed into the prepared hole without further damaging the prepared hole and the adjacent bone tissue, and the prepared hole can be inserted into the prepared hole. When screwing in, it is difficult to drop off from the thread base 23, and a more excellent fitting property and buffering function are exhibited.

  Here, the thickness of the surface porous layer 6 is in contact with the substantial portion 5 where the surface porous layer 6 is disposed when the cross section of the screw base 21 is observed with an electron microscope or the like, and the axis of the living bone fixing screw 1. The first tangent line L1 parallel to the surface porous layer 6 disposed in the substantial part 5 and the shortest distance B between the first tangent line L2 and the second tangent line L2 parallel to the first tangent line L1, or the top of the thread base 23. A fourth tangent line L4 parallel to the axis of the living bone fixing screw 1 and a third tangent line L3 in contact with the surface porous layer 6 disposed on the top of the thread base 23 and parallel to the fourth tangent line L4. Measured as the shortest distance C. The thickness of the surface porous layer 6b disposed on the flank of the thread base 23 is measured basically in the same manner.

  At least a part of the surface porous layer 6a formed on the valley bottom 25 has a height difference of 200 to 800 μm with respect to the thread base 23 adjacent to the valley bottom 25 on which it is formed, that is, the surface of the surface porous layer 6a and the screw. The height of the mountain base 23 has an altitude difference of 200 to 800 μm. When this altitude difference is less than 200 μm, the anchor effect on the pilot hole of the screw thread 17 is small, the screwing force with the pilot hole is reduced and the initial fixing property is inferior, and the living bone fixing screw 1 is screwed into the pilot hole. In addition, the surface porous layer 6a may be compressed or dropped, and even if the surface porous layer 6a is not damaged or dropped, the amount of living tissue may be reduced, and in any case, high bone bonding property may not be exhibited. On the other hand, if the difference in altitude exceeds 800 μm, the substantial part 5 may have a relatively small diameter, the strength may be reduced, and breakage may easily occur. When the altitude difference exceeds 800 μm, when the living bone fixing screw 1 is screwed into the pilot hole, an excessive screwing torque may be required, and the embedding property may be lowered. May damage bone tissue and cause necrosis.

  The height difference in the surface porous layer 6a formed on the valley bottom 25 is that the strength, initial fixation, bone bonding, and embedding of the living bone fixation screw 1 are all at a higher level. It is preferable that it is 750 micrometers, and it is especially preferable that it is 300-700 micrometers. When the living bone fixing screw 1 is an artificial tooth root used when fixing the artificial tooth to the alveolar bone, the altitude difference is preferably 200 to 400 μm, particularly preferably 250 to 350 μm. .

  The surface porous layer 6a having a height difference of 200 to 800 μm is formed on a part of the valley bottom 25. In other words, a part of the surface porous layer 6a formed on the valley bottom 25 has a height difference of 200 to 800 μm. Yes. The surface porous layer 6 a having an altitude difference of 200 to 800 μm is preferably formed on a valley bottom 25 sandwiched between two adjacent thread bases 23, and preferably has a valley bottom 25 sandwiched between two thread bases 23. It is preferable that it is formed in half or more with respect to the full length, and in this example, it is formed in the whole valley bottom 25 sandwiched between two screw bases 23. The surface porous layer 6a having an altitude difference of 200 to 800 μm may or may not have a thickness of 50 to 500 μm, that is, the surface porous layer 6a having an altitude difference of 200 to 800 μm and 50 to 500 μm. The surface porous layer 6a having the thickness may be the same part or a different part. In this invention, it is preferable that the surface porous layer 6a having a height difference of 200 to 800 μm has a thickness of 50 to 500 μm, that is, the surface porous layers 6a and 50 having a height difference of 200 to 800 μm. The surface porous layer 6a having a thickness of ˜500 μm is preferably the same part.

  Here, when the cross section of the screw base 21 is observed with an electron microscope or the like, the altitude difference indicates that the surface of the surface porous layer 6a has a second tangent L2 determined in the same manner as the thickness of the surface porous layer 6, and the thread base. Measured as the shortest distance A with the fourth tangent line L4 that is in contact with the top of the line 23 and parallel to the first tangent line L1.

  As shown in FIG. 3, the surface porous layer 6 has a three-dimensional network-like porous structure having a plurality of small diameter pores 31 and large diameter pores 32. Focusing on the state of existence, the small-diameter pores 31 and the large-diameter pores 32 open to the surfaces of the independent pores 35 that exist independently, the continuous ventilation holes 36 in which two or more independent pores 35 communicate with each other, and the surface porous layer 6. Any or all of the open pores 33 are included. Specifically, the small-diameter pores 31 partially include small-diameter open pores 41 having an average open pore diameter of 5 μm or less that open on the surface of the surface porous layer 6, and the large-diameter pores 32 are formed on the surface of the surface porous layer 6. A large-diameter open pore 42 having an average open pore size of 30 to 1000 μm is included in part. The average open pore diameter of the small diameter open pores 41 is preferably at most 3 μm, and the average open pore diameter of the large diameter open pores 42 is preferably 20 to 300 μm.

  The small-diameter pore 31 and the large-diameter pore 32 are, in addition to the independent pore 35, the continuous vent hole 36, and the open pore 33, the large-diameter open pore 42 and the small-diameter pore 31 and / or the large-diameter pore 32 communicate with each other. The communication hole 34 opened to the inner wall surface 45 of 42 is included. The communication hole 34 is preferably formed with a plurality of communication holes 34 with respect to one open hole 33. As the communication holes 34, the small diameter pores 31 communicate with each other, or the small diameter pores 31 and the large diameter pores 32 communicate with each other, and the small diameter communication holes 43 and the large diameter pores 32 communicate with each other. The diameter communication hole 44 can be mentioned. In order to facilitate attachment of proteins and cells involved in bone formation, the average diameter of the small-diameter communication holes 43 is preferably at most 5 μm, and more preferably at most 3 μm. Further, in order to allow the bone tissue to penetrate into the surface porous layer 6 and to keep the strength of the surface porous layer 6 at the convex portions moderate, the average value of the opening diameters of the large-diameter communication holes 44 at the convex portions is 10 to 300 μm. It is preferable and it is still more preferable in it being 20-200 micrometers. The small-diameter pores 31 and the large-diameter pores 32 have at least one shape selected from the group consisting of spherical, oblate and oblong.

  When the surface porous layer 6 has such a plurality of small-diameter pores 31 and large-diameter pores 32, a large number of openings are formed on the surface of the surface porous layer 6 when the bone fixing screw 1 is implanted. The bone tissue can enter the inside of the surface porous layer 6 through the open pores 33 and the open pores 33 and the communication holes 34. As a result, new bone is formed so as to fill the space existing inside the surface porous layer 6, so that the bone and the bone fixing screw 1 are firmly coupled. Further, the more the communication holes 34, particularly the large-diameter communication holes 44, are formed on the inner wall surface of the large-diameter open holes 42 formed by the large-diameter pores 32, the bone tissue is transferred from the surface of the surface porous layer 6 to the deep part. Therefore, new bone can be formed in the deep part of the surface porous layer 6, and good bonding between the bone and the living bone fixing screw 1 can be ensured. In the living bone fixing screw 1, the surface porous layer 6 b disposed on the thread base 23 is compressed or damaged even when screwed into the pilot hole, but the surface porous disposed on the valley bottom 25. Since the layer 6a does not substantially compress or damage or fall off, the layer 6a exhibits sufficient bone connectivity. And if the surface porous layer 6 and the prepared hole or the bone in the vicinity are firmly bonded after implanting the living bone fixing screw 1 in this way, the initial fixing property can be maintained for a long period of time, and the living bone fixing screw 1 Can be prevented from dropping or pulling out.

  Note that the average open pore diameter of the small-diameter open pores 41 and the average open pore size of the large-diameter open pores 42 opened on the surface of the surface porous layer 6 are obtained by observing the surface of the surface porous layer 6 with a scanning electron microscope or digital microscope. The hole diameter of the communication hole 34 can be obtained from the SEM image taken in the same manner. Specifically, it can be determined by the method described in columns 0054 to 0056 of Patent Document 8 (Japanese Patent Application Laid-Open No. 2010-253195).

  The bone fixing screw 1 includes a substantial part 5 and a surface porous layer 6 integrally formed of the same biocompatible polymer as the substantial part 5, and the surface porous layer 6 a formed at the bottom of the substantial part is at least Some of them have a thickness of 50 to 500 μm and have an altitude difference of 200 to 800 μm with respect to the thread base 23 adjacent to the valley bottom 25, so that stress shielding and metal allergy can be avoided. It is difficult to break, and has both an embedding property and an initial fixing property that are opposite to each other, and also exhibits a high bone bonding property. In particular, the living bone fixing screw 1 includes the surface porous layer 6a and the surface porous layer 6b disposed on the surface of the thread base 23 and the valley bottom 25. In addition to the above effects, the living bone fixing screw 1 When fitting to the pilot hole is improved and higher initial fixation is exhibited, and further, the bone connectivity is further improved and the surface porous layer 6b exhibits a buffering function and the living bone fixing screw 1 is embedded. The fixing stability is maintained for a long time. That is, according to the present invention comprising the surface porous layer disposed on the surface of the thread base and the valley bottom, stress shielding and metal allergy can be avoided and are not easily damaged. In addition, it is possible to achieve the object of providing a living bone fixing screw that combines fixing stability and exhibits even higher bone connectivity. The living bone fixing screw 1 having such an effect is particularly preferably used as an artificial tooth root in which a meshing pressure, a chewing force, etc. act intermittently over a long period of time.

  As shown in FIG. 4, a living bone fixing screw 2, which is another example of a living bone fixing screw according to the present invention, is formed on at least a part or all of the surface of the surface porous layer 6 and the inner wall surface 45 of the pores. It has a supported bioactive substance 7. Therefore, the living bone fixing screw 2 is basically the same as the living bone fixing screw 1 except that the living bone fixing screw 2 has the bioactive substance 7.

  The bioactive substance 7 is in an independent state on the inner wall surface 45 of the open pores 33 in the surface porous layer 3 and / or the surface of the surface porous layer 3 and / or the inside of the surface porous layer 3 and / or these bioactive substances 7. Are bonded and stretched around the surface porous layer 6 in a dendritic manner. Specifically, the bioactive substance 7 is densely supported in the form of a film or a layer on the inner wall surface 45 of the open pores 33 and the surface of the surface porous layer 6. When the bioactive substance 7 is carried on the surface porous layer 6, after the living bone fixing screw 2 is implanted in the living body, a chemical reaction between the bioactive substance 7 and the bone tissue of the living body starts. Bones are rapidly formed and exhibit rapid bone bonding.

The bioactive substance 7 is a substance that has a high affinity with a living body and has a property of chemically reacting with a living tissue such as a bone tissue including a living bone or a tooth tissue including a living tooth (hereinafter referred to as a bone tissue). There is no particular limitation as long as it is present, and examples thereof include a calcium phosphate compound, bioactive glass, and calcium carbonate. Examples of calcium phosphate compounds include calcium hydrogen phosphate, calcium hydrogen phosphate hydrate, calcium dihydrogen phosphate, calcium dihydrogen phosphate hydrate, α-type tricalcium phosphate, β-type tricalcium phosphate, dolomite , Tetracalcium phosphate, octacalcium phosphate, hydroxyapatite, fluorapatite, carbonate apatite, and chlorapatite. Bioactive glass comprises bioglass, crystallized glass (also called glass-ceramics.), Etc., as a bioglass, for _{example, SiO 2 -CaO-Na 2 O} -P 2 O 5 based _glass, SiO 2 -CaO- Na ₂ O—P ₂ O ₅ —K ₂ O—MgO-based glass, SiO ₂ —CaO—Al ₂ O ₃ —P ₂ O ₅ -based glass, and the like can be mentioned. Examples of crystallized glass include SiO _{2. -CaO-MgO-P} 2 _{O 5} based glass (also called apatite wollastonite crystallized glass.), _{and, CaO-Al 2 O 3 -P} 2 O 5 based glass. These calcium phosphate compounds, bioglass, and crystallized glass are described in, for example, “Chemical Handbook Applied Chemistry 6th Edition” (The Chemical Society of Japan, published on January 30, 2003, Maruzen Co., Ltd.), “Development of Bioceramics and “Clinical” (edited by Hideki Aoki et al., April 10, 1987, Quintessence Publishing Co., Ltd.) and the like.

  Among these, the bioactive substance 7 is preferably at least one of a calcium phosphate compound and bioactive glass from the viewpoint of excellent bioactivity. Furthermore, the bioactive substance 7 has a composition, structure, and properties similar to those of a living bone and is stable in the body environment. Hydroxyapatite or tricalcium phosphate is particularly preferable in that it has excellent properties and does not show remarkable solubility in the body.

  The bioactive substance 7 may be supported densely or loosely in the form of a film or layer on the surface of the surface porous layer 6 or may be supported in a dispersed state on the surface of the surface porous layer 6 or the like. When the bioactive substance 7 is supported in the form of a film or a layer, the thickness of the bioactive substance 7 is preferably, for example, 0.1 to 100 μm, and particularly preferably 0.5 to 50 μm. preferable.

  In the case where the bioactive substance 7 is supported in a dispersed state, the area ratio of the bioactive substance 7 when the surface porous layer 3 is projected is at least 5% or more in that rapid bone bonding can be exhibited. Is preferable, and it is especially preferable that it is 20% or more. The area of the bioactive substance 7 includes not only the area of the bioactive substance 7 present on the surface of the surface porous layer 3 but also the living body present on the inner wall surface 45 of the open pores 33 and visible from the outside of the surface porous layer 3. The area of the active substance 7 is also included. This area ratio can be obtained by the method described in column 0078 of Patent Document 8 (Japanese Patent Laid-Open No. 2010-253195). The bioactive substance 7 is preferably supported by 0.5 to 30% with respect to the volume of the surface porous layer 6. This volume ratio can be obtained basically in the same manner as the area ratio.

  The shape of the bioactive substance 7 may be granular, granular or powder that can be supported on the surface of the surface porous layer 6 and the inner wall surface 45, and may be an aggregate, for example, spherical, elliptical, needle Shapes, columnar shapes, rod shapes, plate shapes, polygonal shapes, and the like. The particle diameter of the bioactive substance 7 at this time is preferably 0.001 to 10 μm, for example, and particularly preferably 0.01 to 5 μm. Note that “particle” and “particle diameter” described in the present specification are “primary particle” and “primary particle diameter”, respectively, unless otherwise specified, and are supported on the surface porous layer 6. In the case where the bioactive substance 7 is an aggregate, it is the primary particle that is the minimum unit constituting the aggregate and its diameter. The particle diameter can be calculated by the intercept method. Specifically, a photograph can be taken with a scanning electron microscope, a straight line intersecting at least 15 particles can be drawn, and the average value of the length of the portion where the straight line and the particle intersect can be calculated. If the shape is other than spherical particles, the area-converted diameter is calculated.

  The living bone fixing screw 2 is basically the same as the living bone fixing screw 1 except that the living bone fixing screw 1 has a bioactive substance 7, and thus the living bone fixing screw 1 retains the effect produced by the living bone fixing screw 1. It exhibits faster bone connectivity than the bone fixation screw 1. Therefore, the living bone fixing screw 2 is particularly preferably used as an artificial tooth root in which the meshing pressure, the chewing force, etc. act intermittently over a long period of time.

  As shown in FIG. 5, the living bone fixing screw 3, which is another example of the living bone fixing screw according to the present invention, extends to the tip of the substantial portion 5 along the axis of the substantial portion 5. This is basically the same as the living bone fixing screw 1 except that the core material 8 is embedded.

  The core member 8 is formed in a rod shape with a material to be contrasted with an X-ray, and the tip thereof is disposed at the tip of the substantial part 5, that is, the screw tip. The living bone fixing screw 3 having such a core material 8 has an X-ray position and state when screwed into the pilot hole even if the substantial part 5 and the surface porous layer 6 are formed of a biocompatible polymer. Can be confirmed. Examples of the material to be contrasted with the X-ray include stainless steel, titanium or a titanium alloy, metal such as tantalum, barium sulfate, zirconium dioxide and the like. When the core material 8 is made of metal in the living bone fixing screw 3, it is preferable that the core material 8 is not exposed on the surface of the living bone fixing screw 3 because metal allergy can be avoided.

  The living bone fixing screw 3 is basically the same as the living bone fixing screw 1 except that the living body bone fixing screw 1 includes the core material 8. The embedded state of the bone fixation screw 1 can be easily confirmed. Therefore, the living bone fixing screw 3 is particularly preferably used as an artificial tooth root in which the meshing pressure, the chewing force, etc. act intermittently over a long period of time.

  Specifically, the living bone, artificial tooth or artificial joint embedded in or fixed to the defect or joint using the living bone fixing screw according to the present invention including the living bone fixing screws 1 to 3, specifically, the living bone to be screwed Prepare a pilot hole with a diameter difference from the fixing screw in the above range near the defect or joint, screw a living bone fixing screw into this prepared hole, and attach and fix artificial teeth etc. to the living bone fixing screw as desired Is implemented.

  The living bone fixing screw according to the present invention is manufactured by a method in which the substantial part and the surface porous layer can be integrally formed of the same biocompatible polymer. Examples of such a method include a method including a step of forming a surface porous layer by foaming a part of a substantial part, usually the surface. A method of manufacturing the living bone fixing screw 1 or 2 by this method (hereinafter referred to as one manufacturing method) will be described.

  This one manufacturing method includes a first step in which a molded body that is a base material for the bone fixing screw 1 or 2 is molded with a biocompatible polymer, and a surface of the molded body obtained in the first step. A second step of obtaining a microporous substrate by forming micropores in the surface region forming the layer, and foaming by immersing the microporous substrate obtained in the second step in a solution containing a foaming agent A third step of obtaining an agent-holding substrate, and a foaming substrate by immersing the foaming agent-holding substrate obtained in the third step in a foaming solution that swells the biocompatible polymer and foams the foaming agent. A fourth step to be obtained; a fifth step to immerse the foamed base material obtained in the fourth step in a coagulation solution that coagulates the swollen biocompatible polymer; and a surface porous layer formed in the fifth step if desired. And a sixth step of supporting the bioactive substance on That.

  In this one manufacturing method, first, the first step is performed. Specifically, a molded body to be a base material for the bone fixing screw 1 or 2 is molded using the biocompatible polymer. This molded body is basically similar to the living bone fixing screw 1 or 2, the head molded body serving as the base material of the head 11, the cylindrical body molded body serving as the base material of the cylindrical body 12, and the screw portion 13. The threaded body formed as a base material is continuously provided in this order along the axial direction. This molded body is set to an appropriate size in consideration of being converted to a surface porous layer in a process described later. The method for molding the biocompatible polymer is not particularly limited, and examples thereof include a method of injection molding using a mold having a cavity with a predetermined dimension, a method of cutting a cylindrical body formed by extrusion molding, and the like. It is done.

  In this one manufacturing method, the second step is then performed. Specifically, a microporous substrate having a large number of micropores on the surface of the molded body molded in the first step is produced. As a method for forming micropores in the molded body, a known method can be adopted. For example, the molded body is immersed in a corrosive solution such as concentrated sulfuric acid, concentrated nitric acid, or chromic acid for a predetermined time, and then biocompatible. Examples include a method of immersing in a cleaning solution in which the soluble polymer does not elute, for example, pure water for a predetermined time. For example, when polyether ether ketone (PEEK) is employed as the biocompatible polymer, micropores can be formed by immersing PEEK in concentrated sulfuric acid for a predetermined time and then immersing in pure water for a predetermined time. In this second step, the portion immersed in the corrosive solution may be a portion of the molded body that forms the surface porous layer. Specifically, the screw serving as the base material of the screw portion 13 of the molded body. This is a molded part.

  The pore diameter of the micropores formed on the surface is sufficient if it has a pore diameter that allows the foaming agent used in the next third step to enter the base material made of the biocompatible polymer. It can select suitably according to the kind of agent. For example, when sodium carbonate is used as the foaming agent, the pore diameter of the micropores is preferably 0.1 to 200 μm.

  The porosity of the micropores formed on the surface should be sufficient to retain the blowing agent used in the third step. For example, when sodium carbonate is used as the blowing agent, the biocompatible polymer The porosity of the layer in which the micropores of the manufactured substrate are formed is preferably 10 to 90%. When the porosity is in a low range within the porosity range, for example, a state in which pores are formed in communication from the surface of the base material to the internal direction, or a columnar shape perpendicular to the internal direction from the surface of the base material. It is preferable that the pores are formed so that the foaming agent is maintained at a desired depth from the surface of the substrate, such as in a state where the pores are formed. The thickness of the layer in which a large number of micropores are formed is preferably equal to the thickness of the porous surface layer 6 in the living bone fixing screw 1 or 2 that is the final product.

  The thickness, pore diameter, and porosity of the layer having a large number of micropores are determined depending on the time and / or temperature of immersing PEEK in concentrated sulfuric acid when, for example, concentrated sulfuric acid is used as the corrosive solution of PEEK. Can be adjusted. Moreover, a pore diameter and a porosity can be adjusted with the kind and / or temperature, etc. of the washing | cleaning solution immersed after immersing in concentrated sulfuric acid. The pore diameter is basically the same as the average open pore diameter, and the porosity can be obtained by the method described in the 0037 column of Patent Document 7 (International Publication No. 2009/095960 pamphlet).

  In this one manufacturing method, the third step is then performed on at least a portion of the molded body where the surface porous layer is formed, specifically, a threaded molded body. Specifically, the microporous substrate obtained in the second step is immersed in a solution containing a foaming agent for a predetermined time, and the foaming agent is held on the surface of the microporous substrate having a large number of micropores. A foaming agent holding substrate is produced. The foaming agent may be any substance that can form a desired porous structure on the surface of a biocompatible polymer substrate. Examples of such foaming agents include inorganic foams such as carbonates and aluminum powders. And organic foaming agents such as azo compounds, azo compounds and isocyanate compounds. The foaming agent is preferably a substance that does not adversely affect the living body, and as such a foaming agent, carbonates are preferable, and examples thereof include sodium hydrogen carbonate, sodium carbonate, and potassium carbonate.

  In this one manufacturing method, the fourth step is then performed on at least a portion of the molded body where the surface porous layer is formed, specifically, a threaded molded body. Specifically, the foaming agent holding substrate obtained in the third step is immersed in a foaming solution for swelling the biocompatible polymer and foaming the foaming agent for a predetermined time, and the swelling of the biocompatible polymer is performed. A foamed substrate formed by simultaneously proceeding with foaming of the foaming agent is produced. Examples of the foaming solution include acidic solutions such as concentrated sulfuric acid, hydrochloric acid, and nitric acid. When the material for forming the foaming agent holding substrate is PEEK and the foaming agent is carbonate, the foaming solution is preferably concentrated sulfuric acid having a concentration of 90% or more.

  In this fourth step, the swollen biocompatible polymer accumulates more swollen biocompatible polymer in the recesses or in the vicinity of the recesses than the protrusions that become the threads 17 due to the surface tension. . That is, in the fourth step, the thickness of the swollen biocompatible polymer is larger in the concave portion than in the convex portion. In the fourth step, the thickness of the swollen biocompatible polymer is adjusted by appropriately adjusting, for example, the concentration of the foaming agent, the time for dipping in the foaming agent, the time for dipping in the foaming solution, and the like. In addition, as for the immersion time of the foaming solution in a 4th process, 5 to 60 minutes are preferable.

  In this manufacturing method, the fifth step is then performed on at least a portion of the molded body where the surface porous layer is formed, specifically, a threaded molded body. Specifically, the living bone fixing screw 1 is manufactured by immersing the foamed base material obtained in the fourth step in a coagulation solution for coagulating the swollen biocompatible polymer. Examples of the coagulation solution, that is, a solution from which the biocompatible polymer does not elute, include aqueous solutions such as water, acetone, and ethanol. When the material for forming the foamed substrate is PEEK, in addition to the above, an inorganic acid aqueous solution such as sulfuric acid, nitric acid, phosphoric acid and hydrochloric acid having a concentration of less than 90%, and a water-soluble organic solvent can be used. Examples of the water-soluble organic solvent include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, ethylene glycol, diethylene glycol, trietylene glycol, propylene glycol, diester. Alcohols such as propylene glycol, glycerol ethanol, propanol, butanol, pentanol, hexanole and their aqueous solutions, polyethylene glycol, polypropylene glycol, polyvinyl pyrrolidone, etc. Mention may be made of molecules or their aqueous solutions and mixtures thereof.

  The foamed substrate obtained in the fourth step may be immersed in at least one solution selected from a plurality of types of solutions that can be used as a coagulation solution, or may be sequentially immersed in a plurality of types of solutions. Further, a mixture of at least two kinds of solutions may be used.

  After the fifth step, it is preferable to wash the foaming agent and the coagulation solution remaining in the living bone fixing screw 1 with pure water.

  A porous structure formed on the surface of a biocompatible polymer base material, that is, a large-diameter open pore diameter, a small-diameter open pore diameter, and a communicating pore diameter that define the porous structure of the surface porous layer 6 of the bone fixing screw 1 And the porosity, etc., appropriately select the type and concentration of the foaming agent, the type and concentration of the foaming solution, the immersion time in the foaming solution, the type and concentration of the coagulation solution, the immersion time in the coagulation solution, the temperature in each step, etc. Can be adjusted.

  In particular, the surface porous layer 6 has a desired porous structure by changing at least one selected from the type of coagulation solution, the concentration of the coagulation solution, and the immersion time in the coagulation solution. The bone fixing screw 1 can be easily obtained. By changing these parameters, the coagulation rate of the swollen biocompatible polymer on the surface of the foam substrate can be controlled. As the type and concentration of the coagulation solution, it is preferable to appropriately select at least one of water and a low coagulation solution that requires a longer time than water to coagulate the swollen biocompatible polymer. When the material forming the foamed substrate is PEEK, sulfuric acid having a concentration of less than 90% can be used as the low coagulation solution.

  For example, when a foamed base material formed by PEEK is immersed in sulfuric acid having a concentration of 86% as a low coagulation solution, PEEK solidifies more slowly than when immersed in water. That is, the coagulation rate becomes slow. Therefore, the porous structure on the surface of the foamed substrate changes as time elapses when the foamed substrate is immersed in the low coagulation solution. The change in the surface structure of the foamed substrate due to the difference in the immersion time of the foamed substrate in the low coagulation solution is specifically described in Patent Document 8 (Japanese Patent Application Laid-Open No. 2010-253195).

  As described above, it is possible to obtain the living bone fixing screw 1 in which the porous structure of the surface porous layer 6 is different due to the difference in the immersion time of the foamed base material in the low coagulation solution. In particular, if the solidification is quickly completed by immersing in water or the like at the time when the diameters of the large-diameter open pores 42 and the large-diameter communication holes 44 are maximized, the inside of the surface porous layer 6 has good communication properties. A living bone fixing screw 1 can be provided.

  Depending on the type and concentration of the low-coagulation solution, as described above, the manner in which the structure of the surface of the foamed substrate changes with the passage of the immersion time differs. Therefore, select the desired low coagulation solution, immerse the foam substrate for a predetermined time, and when the surface structure of the foam substrate has the desired porous structure, soak in water and quickly swell Since the biocompatible polymer thus obtained can be solidified, the living bone fixing screw 1 in which the surface porous layer 6 has a desired porous structure can be obtained. In order to solidify the swollen biocompatible polymer, in addition to immersing the foamed substrate in water, the swollen biocompatible polymer is dipped in a low coagulation solution for a time sufficient for the swollen biocompatible polymer to solidify. May be.

  In this manner, the living bone fixing screw 1 including the substantial part 5 and the surface porous layer 6 made of the same biocompatible polymer can be manufactured. The living bone fixing screw 1 manufactured by this one manufacturing method is basically white when the molded body is formed of PEEK and treated with sulfuric acid, for example, and the living bone fixing screw 1 is used as an artificial tooth root. In some cases, it is excellent in aesthetics.

  In order to manufacture the biological bone fixing screw 2 carrying the bioactive substance 7, the sixth step of carrying the bioactive substance on the surface porous layer obtained in the fifth step is performed in one manufacturing method. As the sixth step, it is possible to employ a liquid phase method in which either a solution containing at least 10 mM calcium ions and a solution containing at least 10 mM phosphate ions are immersed first. The liquid phase method is specifically described in columns 0106 to 0110 of Patent Document 8 (Japanese Patent Laid-Open No. 2010-253195).

  Further, as the sixth step, the living bone fixing screw 1 obtained in the fifth step is immersed in a suspension containing a large amount of a bioactive substance in advance, and dried to fix the bioactive substance. The law can also be adopted. The medium in which the bioactive substance is suspended is not particularly limited as long as the medium does not dissolve the biocompatible polymer, and examples thereof include alcohols such as methanol, ethanol, and propanol, water, acetone, and hexane. Thus, after carrying | supporting a bioactive substance by a 6th process, when immersed in a pure water and washing | cleaning if desired, it is made to dry and the inner wall surface 45 of the open pore in the surface porous layer 6 and / or the surface porous layer 6 is carried out. The biological bone fixing screw 2 having the bioactive substance 7 supported on its surface can be manufactured.

  In this manufacturing method, the biocompatible polymer is formed into a desired shape in the first step, but instead of or in addition to the first step, a desired porous layer is formed after forming the surface porous layer. You may implement the 7th process shape | molded and shaped in a shape.

  The living bone fixing screw according to the present invention is not limited to the above-described example, and various modifications can be made within a range in which the object of the present invention can be achieved.

  The living bone fixing screws 1 to 3 each include the head 11, the cylindrical portion 12, and the screw portion 13. In this invention, the living bone fixing screw does not include the head and the cylindrical portion. The whole may be formed of a screw portion or a complete screw portion, and may not include at least one of a head portion or a cylindrical portion, and an artificial bone or the like is attached to the head portion, if desired, a cylindrical portion or a screw portion. You may have a mounting part, for example, a locking hole.

  The living bone fixing screw 1 has a screw tip 15 as a round tip. However, in this invention, the living bone fixing screw may not have a screw tip, and has a screw tip. However, the tip is not limited to a round tip, and may be a flat tip, a rod tip, a pointed tip, a hollow tip, or the like.

  The living bone fixing screws 1 to 3 each have a spiral screw thread 17 and a screw thread base 23 that continuously rotate a plurality of times. In this invention, the screw thread and the screw thread base are continuous or Any spiral that is discontinuous and rotates at least once is sufficient.

  The living bone fixing screws 1 to 3 are so-called “parallel screws” in which the outer diameter of the screw portion 13 is constant. In the present invention, the outer diameter of the screw portion is the screw tip. It may be a so-called “tapered screw” that gradually decreases toward the center. In the so-called “tapered screw”, the surface porous layer may have a height difference with at least one of the adjacent screw bases within the above range, and the height difference between both screw bases may be within the above range. .

  In the living bone fixing screws 1 to 3, the surface porous layer 6 is disposed on the screw portion 13, but in this invention, the surface porous layer may be disposed at least at a part of the valley bottom. It may not be arranged first, and may be arranged on the head or the cylindrical part in addition to the screw part.

  In the living bone fixing screws 1 to 3, the head portion 11, the cylindrical portion 12 and the screw portion 13 are all formed of PEEK. In this invention, a living body in which the substantial portion of the screw portion and the surface porous layer are the same. The head and the cylinder may be made of different materials as long as they are made of compatible polymers, but they are made of the same or different biocompatible polymers in that they can avoid metal allergies and are hard to break. May be.

  In the living bone fixing screws 1 to 3, the head 11, the cylindrical portion 12, and the screw portion 13 are all provided with a substantial portion. In the present invention, at least the screw portion only needs to include a substantial portion. The substantial part is preferably solid as a whole, but a hollow part or a sparse part may exist in a part.

  The living bone fixing screws 1 to 3 each have a single lead 17 and one screw thread 17. In the present invention, the number of threads, the number of leads, and the like can be set as appropriate.

  In the living bone fixing screw 3, the core material 8 is formed in a rod shape and the tip thereof is disposed at the tip of the substantial part 5. In the present invention, the core material may be needle-like, spherical or powdery. Alternatively, it may be embedded only in the vicinity of the tip of the substantial part.

  In addition, the living bone fixing screw 3 includes a core material 8 formed in a rod shape with a material contrasted with X-rays. In this invention, the core material is formed of a material not contrasted with X-rays, A material to be contrasted by X-rays may be contained in the portion arranged at the tip portion as, for example, a needle shape, a spherical shape, or a powder, or may be embedded in a dispersed manner.

  Further, the living bone fixing screw 3 includes a core material 8 formed in a rod shape with a material contrasted with X-rays. In this invention, the living bone fixing screw is at least a substantial part and a surface porous layer. One side may contain a material to be contrasted with an X-ray. The X-ray contrast material contained in the surface porous layer is preferably not a metal, and specifically, barium sulfate and zirconium dioxide.

(Example 1-1)
A solid round bar (diameter 10 mm, length 100 mm, Victrex 450 G) formed of polyether ether ketone (glass transition temperature 143 ° C., melting point 340 ° C., elastic modulus 4.2 GPa, flexural strength 170 MPa) is appropriately cut. Then, after processing into a screw shape having the following dimensions with a lathe, it was immersed in pure water and cleaned by irradiating with ultrasonic waves to prepare a molded body.
<Dimensions>
Head molded body: axial length 1.5 mm, maximum outer diameter 4.8 mm, minimum outer diameter 3.9 mm
Cylindrical compact: axial length 1.5 mm, outer diameter 3.9 mm
Threaded part molded body: axial length 9.0 mm, outer diameter 4.2 mm,
Full screw part: Axis length 7.0 mm, outer diameter 4.2 mm, valley diameter 3.0 mm, pitch 1.0 mm, lead 1.0 mm, number of rotations of convex part 7 to be thread base, convex The height of the part is 0.6 mm, the angle of the convex part is 60 °, the distance parallel to the axis of the part that becomes the valley bottom of the thread groove base is 0.3 mm
Screw tip: axial length 2.0 mm, outer diameter 3.0 mm, curvature radius 1.5 mm

  The molded part of the screw part is immersed in 30 mL of concentrated sulfuric acid (concentration: 97%) at room temperature for 5 minutes, then pulled up from sulfuric acid and immersed in pure water for 5 minutes, and then the pH of the pure water is neutral. It washed repeatedly until it became, and the microporous base material which has a micropore on the surface was obtained (2nd process). In this microporous substrate, the pore diameter was 2 μm, the porosity was 40%, the thickness of the layer was 72 μm at the convex portion serving as the thread base, and 259 μm at the portion serving as the valley bottom of the screw groove base.

  This microporous substrate was immersed in a 50 mL aqueous solution of sodium bicarbonate (concentration: 500 mM) at room temperature for 60 minutes to retain sodium bicarbonate on the surface of the microporous substrate to obtain a foaming agent-retaining substrate. (Third step). The surface of PEEK in the foaming agent holding base material is immersed in 25 mL of concentrated sulfuric acid (concentration: 97%) for 1 minute at room temperature as a foaming solution among the obtained foaming agent holding base material. Simultaneously with the swelling, sodium bicarbonate in the foaming agent holding base was foamed to obtain a foamed base (fourth step). Among the obtained foamed substrates, bubbles formed on the surface of the foamed substrate are immersed in 25 mL of sulfuric acid (concentration: 86%) for 5 minutes at room temperature which is a low coagulation solution. (5th process).

  Next, the surface of PEEK was solidified by pulling up the foamed base material from concentrated sulfuric acid and immersed in pure water for 10 minutes, and washed repeatedly until the pH of the pure water became neutral (6th step). And dried for 3 hours to produce a bone fixing screw 1.

The living bone fixing screw 1 manufactured as described above had the following dimensions. In addition, as shown below, the screw part 13 holding the profile of the screw thread base part 23 was formed.
Head 11: axial length 1.5 mm, maximum outer diameter 4.8 mm, minimum outer diameter 3.9 mm
Cylindrical body 12: axial length 1.5 mm, outer diameter 3.9 mm
Screw part 13: Axis length 9.0 mm, outer diameter 4.2 mm,
Completely threaded portion 14: axial length 7.0 mm, outer diameter 4.2 mm, valley diameter 3.4 mm, pitch 1.0 mm, lead 1.0 mm, rotational speed 7 of thread 17, height of thread 17 ( The surface porous layer 6 is included.) 0.7 mm, the angle of the thread 17 is 62 °, and the distance parallel to the axis of the valley bottom 25 is 0.3 mm.
Screw tip 15: axial length 2.0 mm, outer diameter 3.0 mm, curvature radius 1.5 mm
Substrate 5: Axis length 6.9mm, outer diameter 4.0mm, valley diameter 2.8mm, pitch 1.0mm, lead 1.0mm, number of rotations 7 of thread base 23, height of thread base 23 0.6 mm, angle 60 ° of the screw base 23, distance 0.5 mm parallel to the axis of the valley bottom 25
Surface porous layer 6a: thickness of 270 to 300 μm and average of 285 μm
Surface porous layer 6b: thickness is 80 to 120 μm and average is 100 μm
Altitude difference between the surface of the surface porous layer 6a and the height of the adjacent thread base 23: 315 μm on average

  When the surface porous layer of the bone fixing screw 1 was observed with a scanning electron microscope (magnification: 300 times), a large number of small-diameter open pores, large-diameter open pores, small-diameter communication holes, and large-diameter communication holes were confirmed. The average open pore size of the open pores was 2 μm, the average open pore size of the large open pores was 122 μm, the average open pore size of the small open vents was 2 μm, and the average open pore size of the large open vents was 60 μm. .

(Example 1-2)
In Example 1, the pitch is 1.0 mm, the lead is 1.0 mm, the rotational speed of the screw thread 17 is 7, and the distance parallel to the axis of the valley bottom 25 is 0.3 mm. The pitch is 0.7 mm, the lead is 0.7 mm, and the screw thread is rotated. A living bone fixing screw 1 is manufactured in basically the same manner as in Example 1 except that the distance is changed to 0.0 mm, which is parallel to the axis of Equation 10 and the valley bottom 25, and the surface porous layer 6 is as follows. It was.
Surface porous layer 6a: average 392 μm
Surface porous layer 6b: Average of 176 μm
Height difference between the surface of the surface porous layer 6a and the height of the adjacent screw base 23: 208 μm on average

(Example 1-3)
Except that the angle 60 ° of the thread 17 in Example 1 and the distance 0.3 mm parallel to the axis of the valley bottom 25 are changed to the angle 28 ° of the thread 17 and the distance 0.7 mm parallel to the axis of the valley bottom 25. A living bone fixing screw 1 was manufactured basically in the same manner as in Example 1, and the surface porous layer 6 was as follows.
Surface porous layer 6a: average 53 μm
Surface porous layer 6b: average 90 μm
Height difference between the surface of the surface porous layer 6a and the height of the adjacent screw base 23: 547 μm on average

(Example 1-4)
In Example 1, the diameter of the valley is 3.0 mm, the pitch is 1.0 mm, the lead is 1.0 mm, the rotational speed of the thread 17 is 7, the height of the thread 17 is 0.6 mm, the angle of the thread 17 is 60 °, and the valley bottom 25 is The distance parallel to the axis is 0.3 mm, the valley diameter is 1.6 mm, the pitch is 1.5 mm, the lead is 1.5 mm, the number of rotations of the thread 17 is 4, the height of the thread 17 is 1.3 mm, the angle of the thread 17 A living bone fixing screw 1 is manufactured in substantially the same manner as in Example 1 except that the distance is changed to 28 ° and a distance 0.0 mm parallel to the axis of the valley bottom 25, and the surface porous layer 6 is as follows. It was.
Surface porous layer 6a: Average 492 μm
Surface porous layer 6b: 199 μm on average
Altitude difference between the surface of the surface porous layer 6a and the height of the adjacent screw base 23: 796 μm on average.

(Example 2-1)
After pulverizing and mixing calcium hydrogen phosphate dihydrate (manufactured by Kanto Chemical Co., Ltd.) and calcium carbonate (manufactured by Kishida Chemical Co., Ltd.) in a blend amount in a Ca / P ratio of 1.67 using a pot. And calcined at 900 ° C. to obtain hydroxyapatite particles (particle shape: spherical, particle size 0.05 to 0.5 μm) (mechanochemical synthesis method). 3.0 g of the obtained hydroxyapatite particles were put into 200 mL of ethanol and treated with an ultrasonic homogenizer with a frequency of 20 kHz and an output of 200 W for 10 minutes to prepare an ethanol suspension of hydroxyapatite.

  The living bone fixing screw 1 manufactured in Example 1-1 was defoamed in ethanol for 30 minutes and immersed in 200 mL of ethanol suspension at room temperature, and an ultrasonic wave with a frequency of 38 kHz and an output of 200 W was applied. The whole suspension was irradiated for 15 minutes with an ultrasonic cleaner. Thereafter, the ultrasonic irradiation was stopped, the suspension was stirred for 45 minutes, washed with pure water, heated at 220 ° C. for 3 hours, and then cooled to room temperature to produce a living bone fixing screw 2.

(Example 2-2)
A living bone fixing screw 2 was manufactured basically in the same manner as in Example 2-1, except that the living bone fixing screw 1 manufactured in Example 1-2 was used.

(Example 2-3)
A living bone fixing screw 2 was manufactured basically in the same manner as in Example 2-1, except that the living bone fixing screw 1 manufactured in Example 1-3 was used.

(Example 2-4)
A living bone fixing screw 2 was manufactured basically in the same manner as in Example 2-1, except that the living bone fixing screw 1 manufactured in Example 1-4 was used.

  FIG. 6 shows the result of observation of the screw portion of the living bone fixing screw 2 manufactured in Example 2-1 with a scanning electron microscope (magnification rate 30 times). FIG. 6A is a front enlarged photograph showing the screw portion, and FIG. 6B is a view taken along a plane including the axis of the screw portion of the living bone fixing screw 2 manufactured in Example 2-1. It is a cross-sectional enlarged photograph (magnification rate 100 times) which shows a cut surface. It can be understood from FIG. 6 that the threaded portion includes the substantial portion 5 and the surface porous layer 6 integrally formed on the surface thereof.

  The result of observing the thread 17 of the threaded portion of the living bone fixing screw 2 manufactured in Example 2-1 with a scanning electron microscope at a magnification of 300 times is shown in FIG. The result observed with a scanning electron microscope at a rate is shown in FIG. Moreover, the result of having observed the thread groove 18 of the screw part of the biological bone fixing screw 2 manufactured in Example 2-1 with a scanning electron microscope at a magnification of 300 times is similarly 3000 times as shown in FIG. FIG. 8B shows the result of observation with a scanning electron microscope at an enlargement ratio of. In FIGS. 7B and 8B, the bioactive substance appears in the form of white particles. As shown in FIGS. 7 and 8, it was confirmed that hydroxyapatite was supported on the surface of the surface porous layer 6 and the inner wall surface 45. From this, it was easily estimated that the living bone fixing screw 2 exhibits high bone bonding properties when embedded in the living body.

(Evaluation of embedding)
A pseudo-bone model created using an implant training model (T6-X. 1143F, manufactured by Nissin) was provided with a pilot hole having an inner diameter of 3.6 mm, and the living body manufactured in Examples 2-1 to 2-4 in this pilot hole The bone fixing screw 2 was screwed in. The implantability of the living bone fixing screw 2 at this time was evaluated based on the torque when the living bone fixing screw 2 was screwed in, the damage condition of the living bone fixing screw 2 and the pseudo bone model. The evaluation criteria were good embeddability when the maximum torque when screwing was measured with a torque gauge and the value was 45 cN · m or less. The results are shown in Table 1.

(Initial fixation evaluation)
The fixation state of the living bone fixing screw 2 implanted in the pseudo bone model was evaluated according to the following criteria based on the screwed state and the fitting property with respect to the prepared hole in the same manner as in the evaluation of the implantability. The evaluation standard is that after tightening the living bone fixing screw 2 manufactured in Examples 2-1 to 2-4 with a tightening torque of 30 cN · m into the prepared hole, the presence or absence of shaking is confirmed by hand. In this case, the initial fixability was good. As a result, any of the living bone fixing screws 2 had good initial fixability.

(Check the state of the surface porous layer)
The state of the surface porous layer 6b placed on the screw base 23 is taken out by taking out the living bone fixing screw 2 manufactured in Example 2-1 implanted in the pseudo bone model in the same manner as the embedding evaluation. The results observed with a microscope are shown in FIG. 9A (50 × magnification) and FIG. 9B (10000 × magnification). In FIG. 9B, the bioactive substance appears in the form of white particles. From FIG. 9, although the surface porous layer 6b was partially compressed when embedded in the pilot hole and a part of the porous structure was destroyed, the surface porous layer 6b remained without peeling and remained. It was confirmed that the bioactive substance was still supported on the porous surface layer 6b. Moreover, it has confirmed that the porous structure was maintained by the surface porous layer 6a formed in the valley bottom 25. FIG. Similar results were obtained for Examples 2-2 to 2-4.

(Evaluation of buffer function) and (Retention evaluation of fixed state)
In the confirmation of the state of the surface porous layer, the surface porous layer 6b was partially compressed when embedded in the pilot hole, and a part of the porous structure was destroyed, but the surface porous layer 6b remained without peeling. It was confirmed that the bioactive substance was still supported on the remaining surface porous layer 6b. In addition, it was determined that the porous structure was maintained in the surface porous layer 6a formed on the valley bottom 25, so that the buffer function and the retention in the fixed state were naturally exhibited.

  By the way, except for using the living bone fixing screw 1 manufactured in Examples 1-1 to 1-4, the embedding property, the initial fixing property, and the holding of the fixing state were evaluated as described above, and the surface The state of the porous layer was confirmed. As a result, an embedding property basically similar to that of the living bone fixing screw 2 was obtained, and the initial fixing property and the holding of the fixing state were maintained at a practical level.

  Except that the inner diameter of the pilot hole was changed to 3.5 mm or 3.8 mm, the embedding property, initial fixability, buffer function and retention of the fixed state were evaluated as described above, and the state of the surface porous layer was confirmed. As a result, basically the same result was obtained.

  A living bone fixing screw 1 according to the present invention is suitably used as a living bone fixing screw for embedding or fixing a living bone, an artificial tooth (also referred to as a denture) or an artificial joint, and a bone fixing screw, an artificial tooth root ( It is also referred to as a dental implant). The living bone fixing screw 1 according to the present invention is used for living bodies such as animals and humans.

1, 2, 3 Bone fixing screw 5 Substrate 6, 6 a, 6 b Surface porous layer 7 Bioactive substance 8 Core material 11 Head 12 Cylindrical part 13 Screw part 14 Complete screw part 15 Screw tip 17 Screw thread 18 Screw groove 19 Core material 21 Screw base 23 Screw base 24 Screw groove base 25 Valley bottom 31 Small diameter pore 32 Large diameter pore 33 Open hole 34 Communication hole 35 Independent hole 36 Communication hole 41 Small diameter open hole 42 Large diameter open hole 43 Small diameter communication hole 44 Large Diameter communication hole 45 Inner wall surface L1 First tangent L2 Second tangent L3 Third tangent L4 Fourth tangent

Claims (8)

A substantial portion having a screw base portion formed with a screw base portion that rotates at least once on a peripheral side surface, and a surface porous layer integrally formed of the same biocompatible polymer as the substantial portion at least at the bottom of the screw base portion. Prepared,
The surface porous layer formed on the valley bottom has a thickness of at least a part of 50 to 500 μm, and has a height difference of 200 to 800 μm with respect to the thread base adjacent to the valley bottom. Biological bone fixation screw.   The living bone fixing screw according to claim 1, wherein the surface porous layer is formed on a surface of a screw thread base and the bottom of the valley.   The living bone fixing screw according to claim 1, wherein the valley bottom has a flat bottom surface or curved surface.   The living bone fixing screw according to any one of claims 1 to 3, wherein the biocompatible polymer is polyetheretherketone.   The screw for living bone fixation according to any one of claims 1 to 4, wherein the surface porous layer carries a bioactive substance on at least a part of a surface and a pore inner wall surface.   The living bone fixing screw according to any one of claims 1 to 5, which is used when an artificial tooth is fixed to an alveolar bone with an altitude difference of 200 to 400 µm.   The living bone fixing screw according to any one of claims 1 to 6, further comprising a core material formed of a material to be contrasted with an X-ray and embedded in at least a tip portion of the substantial portion.   The material according to any one of claims 1 to 6, wherein the core material embedded in at least one of the substantial part and the surface porous layer, or at least a tip part of the substantial part, contains a material to be contrasted by X-rays. A living bone fixing screw according to the description.

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