BAR FOR SPINE SUPPORT

Description

Technical FieldReference

[0001] The present application claims priority based on Japanese Patent Application No. 2020-163964 (filed on September 29, 2020).

[0002] The present invention relates to a fixture rod used for a fixture for fixing the spine.Background Art

[0003] Conventionally, a fixture rod using metal as a fixture for fixing the spine has been known.

[0004] US 2013 / 0204368 A1 describes a pultrusion process for manufacturing fiber-reinforced composite materials with a low percentage of continuous fibers , resulting in more flexible articles (e.g., medical implants) compared to traditional high-fiber composites.

[0005] EP 2 389 124 B1 discloses an intramedullary bone nail, comprising a core and an outer layer consisting of substantially linear, longitudinally oriented fibers embedded in a polymer matrix, aligned parallel to the nail's longitudinal axis; and a sleeve, positioned between the core and the outer layer, is designed primarily to resist torsional loads and comprises multiple layers of fibers embedded in a polymer matrix, with the fibers helically wound in opposite directions.

[0006] US 2009 / 0163955 A1 discloses spinal pedicle rod comprising an internally reinforced polymeric core that is at least partially encased within at least one polymeric coating.

[0007] US 2006 / 0247638 A1 describes a spinal fixation system has composite rod or plate comprising mixture of metal and polyetheretherketone or other non-resorbable or resorbable polymeric material.

[0008] WO 2007 / 097905 A2 discloses a flexible composite connecting rod comprises a rod member formed of a suitable, flexible, biocompatible material, such as polyurethane, UHMW polyethylene, PEEK or Teflon, having a desired compression strength.

[0009] WO 2006 / 044315 A2 discloses a threaded rod having a tubular core consisting of a continuous fiber composite and an outer layer of substantially random fiber composite molded at the surface thereof in the shape of threads.

[0010] Further, as such a fixture rod, for example, Patent Literature 1 discloses a spinal pedicle rod including an internally reinforced polymer core at least partially encased in a polymer coating.Citation ListPatent Literature

[0011] Patent Literature 1: Japanese Translation of PCT International Application Publication No. 2011-508623Summary of Invention

[0012] The present invention is defined in claim 1 while preferred embodiments are set forth in the dependent claims.Technical Problem

[0013] A fixture rod using metal is generally excellent in fixing force and strength, but has a problem that a magnetic field is affected by magnetization of the metal in the magnetic field at the time of imaging by MRI or the like, image disturbance occurs, and diagnosis based on a captured image is difficult. On the other hand, with the rod disclosed in Patent Literature 1, although there is no such problem, it is found that it is difficult to impart desired rigidity because the fiber density is low, and there is difficulty in strength and durability.

[0014] One object of the present invention is to provide a fixture rod that reduces damage at the time of fixing with a screw, has high rigidity, and has high durability against a deformation load. Other objects of the present invention will become apparent by reference to the entire specification.Solution to Problem

[0015] A fixture rod according to one embodiment of the present invention is configured to comprise a core member and a reinforcing fiber layer provided on the core member.

[0016] The fixture rod according to one embodiment of the present invention is configured to comprise a covering layer provided on the reinforcing fiber layer.

[0017] In the fixture rod according to one embodiment of the present invention, the core member is formed by a resin containing a fiber.

[0018] In the fixture rod according to one embodiment of the present invention, the fiber is any of carbon, glass, aramid, boron, or SiC, and the resin is any of epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK.

[0019] In the fixture rod according to one embodiment of the present invention, the reinforcing fiber layer is a fiber-reinforced resin, carbon, glass, boron, SiC, or aramid is used as a fiber, and epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK is used as a resin.

[0020] In the fixture rod according to one embodiment of the present invention, it is configured such that a fiber of the reinforcing fiber layer is a long fiber.

[0021] In the fixture rod according to one embodiment of the present invention, it is configured such that a fiber content of the reinforcing fiber layer is 60 weight% or more.

[0022] In the fixture rod according to one embodiment of the present invention, the reinforcing fiber layer comprises a plurality of reinforcing fiber layers, and at least one of the reinforcing fiber layers is an oblique fiber layer in which a fiber direction is inclined with respect to an axial length direction.

[0023] In the fixture rod according to one embodiment of the present invention, the oblique fiber layer has a fiber angle in a range of 5° to 85° or -5° to -85°.

[0024] In the fixture rod according to one embodiment of the present invention, fiber directions of the reinforcing fiber layers are aligned, and thicknesses of the layers are in a range of 0.02 mm to 0.25 mm.

[0025] In the fixture rod according to one embodiment of the present invention, when the reinforcing fiber layer comprises a plurality of reinforcing fiber layers, a bending elastic modulus of a fiber used in at least one or more reinforcing fiber layers of the plurality of reinforcing fiber layers is larger than a bending elastic modulus of the core member.Advantageous Effects of Invention

[0026] According to each of the above embodiments of the present invention, it is possible to provide a fixture rod that reduces damage at the time of fixing with a screw, has high rigidity, and has high durability against a deformation load.Brief Description of Drawings

[0027] Fig. 1 is a view illustrating a spinal fixture 10 comprising a fixture rod according to one embodiment of the present invention. Fig. 2 is a view schematically illustrating a cross section of the fixture rod according to one embodiment of the present invention taken along a plane perpendicular to a central axis thereof. Fig. 3 is a view schematically illustrating a cross section of the fixture rod according to one embodiment of the present invention taken along a plane perpendicular to a central axis thereof. Fig. 4 is a view illustrating each layer of the fixture rod according to one embodiment of the present invention. Fig. 5 is a view schematically illustrating a cross section of the fixture rod according to one embodiment of the present invention taken along a plane perpendicular to a central axis thereof. Fig. 6 is a view illustrating a member used for manufacturing the fixture rod according to one embodiment of the present invention. Description of Embodiments

[0028] Hereinafter, an embodiment of a fixture rod according to the present invention will be specifically described with reference to the accompanying drawings. Components common in the plurality of drawings are denoted by the same reference numerals throughout the plurality of drawings. Note that the drawings are not necessarily drawn to scale for convenience of description.

[0029] Fig. 1 is a view illustrating a spinal fixture 10 comprising a fixture rod 1 according to one embodiment of the present invention. As illustrated in the drawing, the spinal fixture 10 comprises a plurality of screw members 18 (two screw members 18 in the example illustrated in the drawing) to be fixed to the bone of the spine, a plurality of rod fixing members 20 (two rod fixing members 20 in the example illustrated in the drawing) attached to the screw members 18 and each comprising a recess 21 for receiving the fixture rod and a pressing member 22, and the fixture rod 1 inserted into the recess 21 of the plurality of rod fixing members 20 and fixed by the pressing member 22.

[0030] Next, the fixture rod 1 according to one embodiment of the present invention used for the spinal fixture 10 will be described with reference to Fig. 2. Fig. 2 illustrates the fixture rod 1 illustrated in Fig. 1 in the X-X section as illustrated in Fig. 1. As illustrated in the drawing, it is configured such that the fixture rod 1 according to one embodiment of the present invention comprises a core member 2 and a reinforcing fiber layer 3 provided on the core member 2.

[0031] With the fixture rod 1 according to one embodiment of the present invention, it is possible to provide a fixture rod that reduces damage at the time of fixing with the screw, has high rigidity, and has high durability against a deformation load. More specifically, since a solid double structure is employed and a material having a large average bending elastic modulus is used for the outer layer as described later, it is possible to provide the fixture rod having excellent bending rigidity and crushing strength of the entire rod. Here, the average bending elastic modulus refers to a value calculated by dividing the bending rigidity of the entire corresponding portion by a second moment of the corresponding portion.

[0032] Further, it is configured such that the fixture rod 1 according to one embodiment of the present invention comprises a covering layer provided on the reinforcing fiber layer 3. The covering layer can be formed by, for example, epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK, but is not limited thereto.

[0033] In the fixture rod 1 according to one embodiment of the present invention, the core member 2 is formed by a resin containing a fiber. Further, in the fixture rod 1 according to one embodiment of the present invention, it is configured such that the fiber is any of carbon, glass, aramid, boron, or SiC, and the resin is a thermosetting resin (for example, epoxy, phenol, unsaturated polyester, and the like) or a thermoplastic resin (for example, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, PEEK, or the like). With this configuration, it is possible to increase the bending rigidity and the strength of the core member.

[0034] In the fixture rod 1 according to one embodiment of the present invention, the reinforcing fiber layer 3 is a fiber-reinforced resin, carbon, glass, boron, SiC, or aramid is used as a fiber, and a thermosetting resin (for example, epoxy, phenol, unsaturated polyester, and the like) or a thermoplastic resin (for example, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, PEEK, or the like) is used as a resin. With this configuration, it is possible to increase the bending rigidity and the strength of the reinforcing fiber layer.

[0035] In the fixture rod 1 according to one embodiment of the present invention, it is configured such that a fiber of the reinforcing fiber layer 3 is a long fiber. Since the fibers of the reinforcing fiber layer 3 are long fibers, it is possible to further increase the bending rigidity and the strength.

[0036] Further, in the fixture rod 1 according to one embodiment of the present invention, it is configured such that a fiber content of the reinforcing fiber layer 3 is 60 weight% or more. With this configuration, it is possible to form the fixture rod 1 having high rigidity and excellent durability due to the fiber layer in which the long fibers are focused in high density.

[0037] Next, the fixture rod 1 according to one embodiment of the present invention will be described with reference to Fig. 3. As illustrated in the drawing, it is configured such that the fixture rod 1 according to one embodiment of the present invention comprises a core member 2 and a reinforcing fiber layer 3 provided on the core member 2, and the reinforcing fiber layer 3 comprises an axial long fiber layer 4 in which a fiber direction is oriented in an axial length direction (front-back direction of a paper surface), and an oblique fiber layer 5 in which the fiber direction is inclined from the axial length direction. The axial long fiber layer 4 has advantages in terms of bending rigidity and bending strength, and the oblique fiber layer 5 has advantages in terms of torsional rigidity and torsional strength, so that it is possible to provide a fixture rod that reduces breakage at the time of fixing with the screw, has high rigidity, and has high durability against a deformation load by the core member 2 and the reinforcing fiber layer 3.

[0038] Further, in the fixture rod 1 according to one embodiment of the present invention, it can be configured such that the reinforcing fiber layer 3 comprises a plurality of reinforcing fiber layers, and at least one of the reinforcing fiber layers is an oblique fiber layer in which a fiber direction is inclined with respect to an axial length direction. With this configuration, since the oblique fiber layer 5 has advantages in terms of torsional rigidity and torsional strength, it is possible to provide a fixture rod that reduces damage at the time of fixing with the screw and has high rigidity and high durability against a deformation load by the core member 2 and the reinforcing fiber layer 3.

[0039] In the fixture rod 1 according to one embodiment of the present invention, the oblique fiber layer has a fiber angle in a range of 5° to 85° or -5° to -85°. Considering the torsional rigidity and the torsional strength, a most effective fiber angle of the oblique fiber layer is about ±45°. This is because the shear modulus at ±45° is maximized and the torsional rigidity is also maximized.

[0040] Further, in the fixture rod 1 according to one embodiment of the present invention, fiber directions of the reinforcing fiber layers are aligned, and thicknesses of the layers are, for example, in a range of 0.02 mm to 0.25 mm. With this configuration, the density of the resin is made uniform, and the variation in strength depending on the portion can be reduced. Further, in the fixture rod according to one embodiment of the present invention, when the reinforcing fiber layer comprises a plurality of reinforcing fiber layers, a bending elastic modulus of a fiber used in at least one or more reinforcing fiber layers of the plurality of reinforcing fiber layers is larger than a bending elastic modulus of the core member. With this configuration, by combining the reinforcing fiber layer with the core member while imparting certain elasticity to the reinforcing fiber layer, it is possible to maintain high bending rigidity and crushing strength of the entire rod.

[0041] Next, the fixture rod 1 according to one embodiment of the present invention will be described with reference to Figs. 4 and 5. As illustrated in the drawing, it is configured such that the fixture rod 1 according to one embodiment of the present invention comprises a core member 2 and a reinforcing fiber layer 3 provided on the core member 2. The core member 2 is formed by PEEK / CF (short fiber), and has an outer shape of about 3.0 mm.

[0042] As illustrated in the drawing, the reinforcing fiber layer 3 is formed by a first stacked layer 6, a second stacked layer 7, and a third stacked layer 8. It is configured such that the first stacked layer 6 is formed by bonding a glass scrim to a UD, the UD has a fiber elastic modulus of 30 t, a resin content (RC) of 24%, and a thickness of about 0.103 mm, and the scrim has a fiber elastic modulus of 7 t, a resin content (RC) of 28%, and a thickness of 0.012 mm.

[0043] In addition, it is configured such that the second stacked layer 7 is formed by bonding two oblique layers together, and the oblique layer has a fiber elastic modulus of 30 t, a resin content (RC) of 30%, a thickness of about 0.051 mm, and an oblique angle of +45° or -45°.

[0044] It is configured such that the third stacked layer 8 is formed by bonding a glass scrim to a UD, the UD has a fiber elastic modulus of 30 t, a resin content (RC) of 24%, and a thickness of about 0.103 mm, and the scrim has a fiber elastic modulus of 7 t, a resin content (RC) of 28%, and a thickness of 0.012 mm.

[0045] Fig. 5 illustrates the fixture rod 1 according to one embodiment of the present invention in which each layer as illustrated in Fig. 4 is formed, as viewed in the X-X cross-section in Fig. 1. As illustrated in the drawing, the fixture rod 1 according to one embodiment of the present invention comprises a core member 2 and a reinforcing fiber layer 3 provided on the core member 2, and the reinforcing fiber layer 3 is formed by the first stacked layer 6, the second stacked layer 7, and the third stacked layer 8 described above.

[0046] With the fixture rod 1 according to one embodiment of the present invention, it is possible to provide a fixture rod that reduces damage at the time of fixing with the screw, has high rigidity, and has high durability against a deformation load. More specifically, since a solid double structure is employed and a material having a large average bending elastic modulus is used for the outer layer as described later, it is possible to provide the fixture rod having excellent bending rigidity and crushing strength of the entire rod. Here, the average bending elastic modulus refers to a value calculated by dividing the bending rigidity of the entire corresponding portion by the second moment of the corresponding portion.

[0047] Next, a method for manufacturing the fixture rod 1 according to one example of the present disclosure will be described. First, as step 1, the prepreg is cut (cutting of the prepreg). Then, as step 2, a core material (for example, carbon solid (long fiber)) is prepared. As step 3, since the core material has no stiffness, a V-groove rail illustrated in Fig. 6(a) is used, and a temporary fixing resin is applied to perform temporary fixing (tentative fixing). In step 4, wrapping with the prepreg is performed.

[0048] Next, in step 5, curing is performed using a grooved straightening die illustrated in Fig. 6(b). The reason for using the straightening die is that it may be slightly bent at the time of winding in step 4 described above, and thus needs to be straightened. Then, cutting is performed in step 6, a tape is removed in step 7, and finally, centerless is performed for outer diameter adjustment in step 8.

[0049] With the fixture rod 1 formed in this manner according to one embodiment of the present invention, it is possible to provide a fixture rod that reduces damage at the time of fixing with a screw, has high rigidity, and has high durability against a deformation load. More specifically, since a solid double structure is employed and a material having a large average bending elastic modulus is used for the outer layer as described later, it is possible to provide the fixture rod having excellent bending rigidity and crushing strength of the entire rod. Here, the average bending elastic modulus refers to a value calculated by dividing the bending rigidity of the entire corresponding portion by the second moment of the corresponding portion.Reference Signs List

[0050] 1Fixture rod 2Core member 3Reinforcing fiber layer 4Axial long fiber layer 5Oblique fiber layer 6First stacked layer 7Second stacked layer 8Third stacked layer 10Spinal fixture 18Screw member 20Rod fixing member 21Recess 22Pressing member

Claims

1. A fixture rod (1) for a spinal fixture (10), comprising: a core member (2); and a reinforcing fiber layer (3) provided on the core member (2), characterised in that the reinforcing fiber layer (3) comprises an axial long fiber layer (4) in which a fiber direction is oriented in an axial length direction and an oblique fiber layer (5) in which a fiber direction is inclined with respect to an axial length direction, and wherein the oblique fiber layer (5) has a fiber angle in a range of 5° to 85° or -5° to -85°.

2. The fixture rod (1) according to claim 1, further comprising a covering layer provided on the reinforcing fiber layer (3).

3. The fixture rod (1) according to claim 1 or 2, wherein the core member (2) is formed by a resin containing a fiber.

4. The fixture rod (1) according to claim 3, wherein the fiber is any of carbon, glass, aramid, boron, or SiC, and the resin is any of epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK.

5. The fixture rod (1) according to any one of claims 1 to 4, wherein the reinforcing fiber (3) layer is a fiber-reinforced resin, carbon, glass, boron, SiC, or aramid is used as a fiber, and epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK is used as a resin.

6. The fixture rod (1) according to any one of claims 1 to 5, wherein a fiber of the reinforcing fiber layer (3) is a long fiber.

7. The fixture rod (1) according to any one of claims 1 to 6, wherein a fiber content of the reinforcing fiber layer (3) is 60 weight% or more.

8. The fixture rod (1) according to any one of claims 1 to 7, wherein fiber directions of the reinforcing fiber layers (3) are aligned, and thicknesses of the layers are in a range of 0.02 mm to 0.25 mm.

9. The fixture rod (1) according to any one of claims 1 to 8, wherein, when the reinforcing fiber layer (3) comprises a plurality of reinforcing fiber layers, a bending elastic modulus of a fiber used in at least one or more reinforcing fiber layers of the plurality of reinforcing fiber layers is larger than a bending elastic modulus of the core member (2).