Intraspinal fixation instrument rod

Abstract

To provide an intraspinal fixation instrument rod in which breakage is reduced when having a screw fixed thereto, which has high stiffness and high durability against deformation load, and which, even when being fractured, significantly reduces the risk of injury to a human body.SOLUTION: A fixation instrument rod according to one embodiment of the present invention comprises: a core member 6 that contains a fiber-reinforced resin; and a covering resin layer 7 that covers the core member. The covering resin layer exhibits an elongation of at least 30%, and has a thickness in the range of 0.05-0.4 mm.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a rod for an intraspinal fixation device (for convenience, referred to as a fixation device rod in this specification) for use in a fixation device for fixing the spine. [Background technology]

[0002] 2. Description of the Related Art Metal rods for fixation devices are known as fixation devices for fixing the spine.

[0003] As an example of such a rod for a fixation device, for example, Patent Document 1 discloses a spinal pedicle rod having an internally reinforced polymer core at least partially enclosed in a polymer coating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2011-508623 Summary of the Invention [Problem to be solved by the invention]

[0005] Although metal rods for fixation devices generally have excellent fixation power and strength, they have the problem that, during imaging by MRI or the like, the metal is magnetized in the magnetic field, which affects the magnetic field, causing image distortion and making it difficult to diagnose using the captured image. On the other hand, the rod disclosed in Patent Document 1 does not have such problems, but it is difficult to impart the desired rigidity due to the low fiber density, and it is known that it has problems with strength and durability, as well as a safety problem because the thorny fibers are exposed when broken.

[0006] One of the objects of the present invention is to provide a rod for a fixation device that reduces breakage during screw fixation, has high rigidity and high durability against deformation load, and significantly reduces the risk of injury to the human body even in the event of breakage. Other objects of the present invention will become apparent by referring to the entire specification. [Means for solving the problem]

[0007] A rod for a fastener according to one embodiment of the present invention includes a core member containing a fiber-reinforced resin and a coating resin layer that coats the core member, and is configured so that the coating resin layer has an elongation of 30% or more and a thickness in the range of 0.05 mm to 0.4 mm.

[0008] In the rod for a fastener according to one embodiment of the present invention, the fiber volume fraction (VF) near the surface layer of the core member is in the range of 50% to 70%.

[0009] In the rod for a fastener according to one embodiment of the present invention, the fiber volume fraction (VF) near the surface layer of the core member is in the range of 55% to 65%.

[0010] In the rod for fastener according to one embodiment of the present invention, the core member is formed by laminating a plurality of layers.

[0011] In the fastener rod according to one embodiment of the present invention, the resin of the core member and the resin of the coating resin layer are the same thermoplastic resin.

[0012] In the fastener rod according to one embodiment of the present invention, the resin of the resin coating layer is formed by welding a resin tube.

[0013] In a rod for a fastener according to one embodiment of the present invention, the multiple layers of the core member are formed in such a way that, when viewed in cross section, a reinforcing fiber layer and either a resin layer, a reinforcing fiber layer having fibers different from those of the reinforcing fiber layer, or a reinforcing fiber layer having fibers oblique to the fiber direction of the reinforcing fiber layer are alternately formed in multiple layers.

[0014] In a rod for a fastener according to one embodiment of the present invention, the reinforcing fiber layer is a fiber reinforced resin, and carbon, glass, boron, SiC or aramid is used as the fiber, and epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK or PEEK is used as the resin.

[0015] In one embodiment of the present invention, the resin of the resin layer is epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK.

[0016] In a rod for a fastener according to one embodiment of the present invention, the reinforcing fiber layer different from the fibers of the reinforcing fiber layer is a fiber reinforced resin, and carbon, glass, boron, SiC or aramid is used as the fiber, and epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK or PEEK is used as the resin.

[0017] In the rod for a fastener according to one embodiment of the present invention, the reinforcing fiber layer or a reinforcing fiber layer different from the fibers of the reinforcing fiber layer has fibers aligned in one direction, formed in a woven fabric, or oriented randomly. Also, in the rod for a fastener according to one embodiment of the present invention, the fiber direction of the reinforcing fiber layer having fibers oblique to the fiber direction of the reinforcing fiber layer is oblique in the range of 10° to 90°.

[0018] In the rod for a fastener according to one embodiment of the present invention, when a plurality of layers are provided, either a resin layer, a reinforcing fiber layer having fibers different from those of the reinforcing fiber layer, or a reinforcing fiber layer having fibers oblique to the fiber direction of the reinforcing fiber layer, each layer is the same layer or a different layer.

[0019] In the rod for a fastener according to one embodiment of the present invention, the fibers of the reinforcing fiber layer are long fibers.

[0020] In the fastener rod according to one embodiment of the present invention, the reinforcing fiber layer has a fiber content of 60% by weight or more.

[0021] In a rod for a fastener according to one embodiment of the present invention, the fiber direction of the reinforcing fiber layer is aligned, and the thickness of the layer is in the range of 0.02 mm to 0.3 mm.

[0022] In the rod for a fastener according to one embodiment of the present invention, a marker is embedded in the core member. Effect of the Invention

[0023] According to each of the above-described embodiments of the present invention, it is possible to provide a rod for a fixation device that reduces breakage during screw fixation, has high rigidity and high durability against deformation load, and significantly reduces the risk of injury to the human body even in the event of breakage. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 shows a spinal fixation device 10 including a fixation rod according to one embodiment of the present invention. [Diagram 2] 1 is a schematic diagram showing a cross section of a rod for a fastener according to an embodiment of the present invention, cut along a plane perpendicular to its central axis. FIG. [Diagram 3] 1 is a schematic diagram showing a cross section of a core member of a fastener rod according to an embodiment of the present invention, cut along a plane perpendicular to the central axis of the core member; FIG. [Figure 4] 1 is a schematic diagram showing a cross section of a core member of a fastener rod according to an embodiment of the present invention, cut along a plane perpendicular to the central axis of the core member; FIG. [Diagram 5] 1 is a schematic diagram showing a cross section of a core member of a fastener rod according to an embodiment of the present invention, cut along a plane perpendicular to the central axis of the core member; FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of a rod for a fastener according to the present invention will be described in detail with reference to the accompanying drawings. Elements common to multiple drawings are designated by the same reference numerals throughout the multiple drawings. Please note that the drawings are not necessarily drawn to scale for the sake of convenience.

[0026] 1 is a diagram showing a spinal fixation device 10 including a fixation device rod 1 according to one embodiment of the present invention. As shown in the figure, the spinal fixation device 10 includes a plurality of screw members 18 (two screw members 18 in the illustrated example) fixed to the bones of the spine, a plurality of rod fixing members 20 (two rod fixing members 20 in the illustrated example) attached to the screw members 18 and provided with a recess 21 for receiving the fixation device rod 1 and a pressing member 22, and the fixation device rod 1 inserted into the recess 21 of the plurality of rod fixing members 20 and fixed by the pressing member 22.

[0027] Next, referring to FIG. 2, a rod for a fixation device 1 according to one embodiment of the present invention used for a spinal fixation device 10 will be described. FIG. 2 shows the rod for a fixation device 1 shown in FIG. 1 as viewed from the XX cross section shown in the same figure. The rod for a fixation device 1 according to one embodiment of the present invention includes a core member 6 containing a fiber-reinforced resin, which will be described in detail later, and a coating resin layer 7 that covers the core member 6, and is configured so that the elongation of the coating resin layer 7 is 30% or more and has a thickness in the range of 0.05 mm to 0.4 mm. By providing such a coating resin layer 7, even if the internal core member 6 is broken, the coating resin layer 7 can ensure that the core member 6 is covered without being broken, so that the fibers of the core member 6 can be prevented from being exposed to the outside, and the risk of damage to the human body can be significantly reduced even when the core member 6 breaks. More specifically, since the elongation of the coating resin is sufficiently larger than the standard elongation of carbon fiber, which is about 2%, the breakage occurs from the carbon fiber. In addition, if the coating resin has a certain thickness and strength or more, the breakage of the coating resin can be suppressed against the impact force associated with the breakage of the carbon fiber. However, when the thickness of the coating resin exceeds 0.4 mm, breakage of the coating is unlikely to occur, but the outer diameter of the rod itself becomes large, which has a large effect on placement in the body. In addition, the core member described below can reduce breakage during screw fixation and improve durability against deformation load with high rigidity, and the coating resin layer further achieves the above technical effect. Here, in the rod for fixation 1 according to one embodiment of the present invention, a marker is embedded in the core member 6. The marker is made of a radiopaque material and serves to indicate the position of the implant product in the body.

[0028] In the rod 1 for fastener according to one embodiment of the present invention, the fiber volume fraction (VF) near the surface layer of the core member 6 is preferably in the range of 50% to 70%, more preferably in the range of 55% to 65%. Here, the vicinity of the surface layer of the core member 6 refers to a region 0.2 mm inward from the surface of the core member toward the center. When the fiber volume fraction (VF) near the surface layer of the core member 6 is 50% or more, it is possible to efficiently increase the bending rigidity, and it is possible to configure a rod that is less likely to break. In addition, when the volume fraction near the surface of the core member is 50% or more, the bond with the coating resin is not completely integrated. That is, the resin on the surface of the core member and the coating resin are easily firmly integrated, while the bond between the carbon fiber on the surface of the core member and the coating resin is relatively weak. On the other hand, when the fiber volume fraction (VF) near the surface layer of the core member 6 exceeds 70%, the amount of resin on the surface is too small, and therefore sufficient bonding cannot be obtained between the coating resin and the resin of the core member. Because the core component and the coating resin are not completely integrated but are joined weakly to a certain extent, when the internal core component is damaged, cracks develop between the surface of the core component and the layer of coating resin, releasing stress and making it less likely for the coating resin to break.

[0029] In the rod for fastener 1 according to one embodiment of the present invention, the resin of the core member 6 and the resin of the coating resin layer 7 are the same thermoplastic resin. Examples of such thermoplastic resins include PEEK, nylon, PPSU, and PET. In this way, the core member and the coating resin can be stably integrated.

[0030] In the rod for fastener 1 according to one embodiment of the present invention, the resin of the coating resin layer is formed by welding a resin tube. By molding the coating layer into a tube shape in advance in this manner, a coating layer with stable thickness and quality can be formed.

[0031] In the fastener rod 1 according to one embodiment of the present invention, the core member 6 is formed by laminating a plurality of layers, which will be described in detail later.

[0032] Next, the layers of the core member 6 of the rod for fixation device 1 according to one embodiment of the present invention used in the spine fixation device 10 will be described with reference to Figures 3, 4, and 5. Figures 3, 4, and 5 show the core member 6 of the rod for fixation device 1 shown in Figure 1 as viewed from the XX cross section shown in the same figure. Note that for the sake of convenience of explanation, the above-mentioned coating resin layer 7 is omitted.

[0033] As shown in the figures, the multiple layers of the core member 6 of the fixing device rod 1 according to one embodiment of the present invention are formed in such a manner that, when viewed in cross section, reinforcing fiber layers 2 (each of eight reinforcing fiber layers in the examples of FIGS. 3 to 5) and resin layers 3 (each of seven resin layers 3 in the example shown in FIG. 3), reinforcing fiber layers 4 having fibers different from the fibers of the reinforcing fiber layers 2 (each of seven reinforcing fiber layers 4 in the example shown in FIG. 4), or reinforcing fiber layers 5 having fibers oblique to the fiber direction of the reinforcing fiber layers 2 (each of seven reinforcing fiber layers 5 in the example shown in FIG. 5) are alternately formed in multiple layers. Here, the reinforcing fiber layer 2, the resin layer 3 (example shown in FIG. 3), the reinforcing fiber layer 4 (example shown in FIG. 4) different from the fiber of the reinforcing fiber layer, or the reinforcing fiber layer 5 (example shown in FIG. 5) having fibers oblique to the fiber direction of the reinforcing fiber layer are each formed to have a thickness of 0.01 mm to 0.25 mm, but the thickness of the layer may be different depending on the location of the layer (i.e., the layer may be formed so that there are thin parts and thick parts). In addition, the layer may be formed intermittently (i.e., not only may the layer have thin parts and thick parts, but also there may be parts where the layer thickness is 0). Here, the reinforcing fiber layer 5 is a fiber-reinforced resin, and carbon, glass, boron, SiC, or aramid may be used as the fiber, and epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK may be used as the resin.

[0034] According to the core member 6 of the rod for a fixation device 1 according to one embodiment of the present invention, it is possible to provide a rod for a fixation device which reduces breakage during screw fixing, has high rigidity and high durability against deformation load, and has significantly improved safety even when broken. In particular, it has been found that, when the rod for a fixation device 1 according to one embodiment of the present invention breaks, by concentrating stress on any one of the resin layer sandwiched between the reinforcing fiber layers, the reinforcing fiber layer different from the fibers of the reinforcing fiber layer, or the reinforcing fiber layer having fibers oblique to the fiber direction of the reinforcing fiber layer, it is possible to reduce the reinforcing fiber layer from becoming thorny when the rod breaks, and as a result, it is possible to significantly improve safety to the human body.

[0035] In the core member 6 of the rod for fastener 1 according to one embodiment of the present invention, the reinforcing fiber layer 2 is a fiber-reinforced resin, and the fibers are made of carbon, glass, boron, SiC or aramid, and the resin is made of epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK or PEEK. In this way, it is possible to increase the bending rigidity and strength of the rod for fastener 1.

[0036] In the core member 6 of the fastener rod 1 according to one embodiment of the present invention, the resin of the resin layer 3 is epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK or PEEK.

[0037] In the core member 6 of the rod 1 for a fastener according to an embodiment of the present invention, the reinforcing fiber layer 4 having fibers different from those of the reinforcing fiber layer 2 is a fiber-reinforced resin, and the fibers are carbon, glass, boron, SiC, or aramid, and the resin is epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK. In this way, it is possible to increase the bending rigidity and increase the strength of the rod for a fastener. The reason for using a reinforcing fiber layer having fibers different from those of the reinforcing fiber layer 2 is that by using different materials, different properties such as flexibility and vibration absorption other than rigidity and strength can be imparted.

[0038] In the core member 6 of the rod for fastener 1 according to one embodiment of the present invention, the reinforcing fiber layer 2 or the reinforcing fiber layer 4 different from the fibers of the reinforcing fiber layer 2 may have fibers aligned in one direction, formed in a woven fabric, or oriented randomly. In the core member 6 of the rod for fastener 1 according to one embodiment of the present invention, the fiber direction of the reinforcing fiber layer 5 having fibers oblique to the fiber direction of the reinforcing fiber layer 2 may be oblique in the range of 10° to 90°. In this way, by arranging an appropriate layered structure, it is possible to achieve the target strength and rigidity.

[0039] In the core member 6 of the rod 1 for fastener according to one embodiment of the present invention, when any of the resin layer 3, the reinforcing fiber layer 4 different from the fiber of the reinforcing fiber layer 2, or the reinforcing fiber layer 5 having fibers oblique to the fiber direction of the reinforcing fiber layer 2 is provided in a plurality of layers, each layer is the same layer or a different layer (same below). For example, when two layers are provided, the resin layer 3 may be two layers (in this case, each layer is the same), or two different layers such as the resin layer 3 and the reinforcing fiber layer 4 different from the fiber of the reinforcing fiber layer may be provided. When three or more layers are provided, a desired combination may be selected from the above layers. In this way, the target strength and rigidity can be achieved by arranging an appropriate stacking configuration.

[0040] In the core member 6 of the fastener rod 1 according to one embodiment of the present invention, the fibers of the reinforcing fiber layer 2 are long fibers. In this way, the fibers of the reinforcing fiber layer 2 are long fibers, which makes it possible to further increase the bending rigidity and increase the strength.

[0041] In the core member 6 of the rod for fastener 1 according to one embodiment of the present invention, the fiber content of the reinforcing fiber layer 2 is set to 50 volume % or more. In this way, the fiber layer in which long fibers are concentrated at a high density makes it possible to form a rod for fastener 1 having high rigidity and excellent durability.

[0042] In the core member 6 of the rod 1 for a fastener according to one embodiment of the present invention, the fiber direction of the reinforcing fiber layer 2 is aligned, and the thickness of the reinforcing fiber layer 2 is, for example, in the range of 0.02 mm to 0.3 mm. In this way, the density of the resin is made uniform, and it is possible to reduce the variation in strength depending on the part.

[0043] Next, a manufacturing method of the rod for fastener 1 according to one embodiment of the present invention will be described. First, in step 1, any of the reinforcing fiber layer 2, the resin layer 3, the reinforcing fiber layer 4 having fibers different from those of the reinforcing fiber layer, or the reinforcing fiber layer 5 having fibers oblique to the fiber direction of the reinforcing fiber layer is cut to a predetermined size (layer cutting step). Then, in step 2, each layer is laminated in a predetermined arrangement (layer lamination step). In step 3, the layers are set in a predetermined mold and molded under predetermined conditions (for example, a temperature of 380°C and a pressure of 5 MPa to 15 MPa) (molding step). Next, in step 4, the rod for fastener 1 is processed to a final shape and size to form a core member 6 (processing step). Finally, in step 5, a resin tube is welded to form a coating resin layer 7 on the outer surface of the formed core member 6. In this manner, the rod for fastener 1 according to one embodiment of the present invention is formed. It should be noted that, instead of the above-mentioned manufacturing method of the rod for fastener 1, a method in which a plurality of sets of reinforcing fiber bundles impregnated with a liquid resin are prepared, and these are drawn and passed through a die, and then heated and hardened or cooled and solidified (pultrusion molding method) can also be used to form the rod for fastener 1 according to one embodiment of the present invention. In addition, either a thermosetting resin or a thermoplastic resin may be used.

[0044] The rod 1 for fasteners according to one embodiment of the present invention formed in this way makes it possible to provide a rod for fasteners that reduces breakage during screw fastening, has high rigidity and high durability against deformation load, and significantly reduces the risk of injury to the human body even when broken. More specifically, when the core member breaks, the crack develops between the surface of the core member and the layer of the coating resin, and the stress is released, making it difficult for the coating resin to break. In this way, scattering of fragments and fibers due to breakage of the main body is suppressed.

[0045] The dimensions, materials, and arrangement of each component described in this specification are not limited to those explicitly described in the embodiments, and each component can be modified to have any dimensions, materials, and arrangement that can be included in the scope of the present invention. In addition, components not explicitly described in this specification can be added to the described embodiments, and some of the components described in each embodiment can be omitted. [Explanation of symbols]

[0046] 1 Fixation rod (rod for spinal intracorporeal fixation device) 2 Reinforced fiber layer 3 Resin layer 4 Reinforced fiber layer having fibers different from the fibers of reinforcing fiber layer 2 5 Reinforced fiber layer having fibers oblique to the fiber direction of the reinforcing fiber layer 2 6 Core Members 7. Resin coating layer 10 Spinal fixation device 18 Screw member 20 Rod fixing member 21 Recess 22 Pressing member

Claims

1. A rod for a fastener, A core member including a fiber reinforced resin; a coating resin layer that coats the core member, The rod for a fastener is characterized in that the elongation of the coating resin layer is 30% or more and the coating resin layer has a thickness in the range of 0.05 mm to 0.4 mm.

2. 2. The fastener rod of claim 1, wherein the fiber volume fraction (VF) near the surface layer of the core member is in the range of 50% to 70%.

3. 2. The fastener rod of claim 1, wherein the fiber volume fraction (VF) near the surface of the core member is in the range of 55% to 65%.

4. The rod for use in a fastener according to claim 1 , wherein the core member is formed by laminating a plurality of layers.

5. 2. The rod for use in a fastener according to claim 1, wherein the resin of said core member and the resin of said coating resin layer are the same thermoplastic resin.

6. 2. The rod for use as a fastener according to claim 1, wherein the resin of the coating resin layer is formed by welding a resin tube.

7. 5. The rod for a fastener according to claim 4, wherein the plurality of layers of the core member are formed by alternately forming a plurality of layers of reinforcing fiber layers and either a resin layer, a reinforcing fiber layer having fibers different from those of the reinforcing fiber layer, or a reinforcing fiber layer having fibers oblique to the fiber direction of the reinforcing fiber layer, when viewed in cross section.

8. 8. The rod for fastener according to claim 7, wherein the reinforcing fiber layer is a fiber reinforced resin, and the fiber is carbon, glass, boron, SiC or aramid, and the resin is epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK or PEEK.

9. 8. The rod for fastener according to claim 7, wherein the resin of the resin layer is epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK or PEEK.

10. 8. The rod for fastener according to claim 7, wherein the reinforcing fiber layer different from the fiber of the reinforcing fiber layer is a fiber reinforced resin, and the fiber is made of carbon, glass, boron, SiC or aramid, and the resin is made of epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK or PEEK.

11. The rod for a fastener according to claim 7 , wherein the reinforcing fiber layer or a reinforcing fiber layer different from the fibers of the reinforcing fiber layer has fibers aligned in one direction, formed in a woven fabric, or randomly oriented.

12. 8. The rod for a fastener according to claim 7, wherein the fiber direction of the reinforcing fiber layer having fibers oblique to the fiber direction of the reinforcing fiber layer is oblique in a range of 10 degrees to 90 degrees.

13. 8. The rod for fastener according to claim 7, wherein when a plurality of layers of any of the resin layer, the reinforcing fiber layer having fibers different from those of the reinforcing fiber layer, or the reinforcing fiber layer having fibers oblique to the fiber direction of the reinforcing fiber layer are provided, each layer is the same layer or a different layer.

14. 8. The fastener rod of claim 7, wherein the fibers of the reinforcing fiber layer are long fibers.

15. 8. The rod for fastener according to claim 7, wherein the fiber content of the reinforcing fiber layer is 50 volume % or more.

16. 8. The rod for a fastener according to claim 7, wherein the fiber direction of the reinforcing fiber layer is aligned, and the thickness of the reinforcing fiber layer is in the range of 0.02 mm to 0.3 mm.

17. The rod for fastener according to claim 1 , wherein the core member has a marker embedded therein.

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