Rods for spinal fixation devices

Abstract

To provide a rod for a fixture in which a damage at the time of screw fixation is reduced, the rod having high rigidity and high durability against a deformation load and having significantly improved safety even at the time of breaking.SOLUTION: In a rod for a fixture 1, when a cross section thereof is viewed, a reinforcement fiber layer 2, a resin layer 3, and either a reinforcement fiber layer different from a fiber of the reinforcement fiber layer or a reinforcement fiber layer having a fiber skewed with respect to a fiber direction of the reinforcement fiber layer are alternately formed and each formed in plural layers.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a rod for a fixture used for fixing the spine.

Background Art

[0002] Conventionally, a rod for a fixture using metal as a fixture for fixing the spine has been known.

[0003] Also, as such a rod for a fixture, for example, Patent Document 1 discloses a spinal pedicle rod having an internally reinforced polymer core at least partially placed in a polymer coating.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Although a rod for a fixture using metal generally has excellent fixing force and strength, when imaging is performed by MRI or the like, the magnetic field is affected by the magnetization of the metal in the magnetic field, resulting in image distortion and making it difficult to diagnose based on the captured image. On the other hand, although the rod disclosed in Patent Document 1 does not have such a problem, it is difficult to impart the desired rigidity because the fiber density becomes low, and there are difficulties not only in strength and durability but also in safety because the spiky fibers are exposed at the time of breakage.

[0006] One of the objects of the present invention is to provide a rod for a fixture that reduces breakage during screw fixation, has high rigidity and high durability against deformation loads, and also has significantly improved safety even at the time of breakage. These other objects of the present invention will become clear by referring to the entire specification. [Means for solving the problem]

[0007] In one embodiment of the present invention, a rod for a fastener is formed in cross-section with multiple layers of alternating reinforcing fiber layers, resin layers, reinforcing fiber layers having fibers different from those of the reinforcing fiber layer, or reinforcing fiber layers having fibers oblique to the fiber direction of the reinforcing fiber layer.

[0008] In a fixing rod according to one embodiment of the present invention, the reinforcing fiber layer is a fiber-reinforced resin, wherein 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.

[0009] In a fixing rod according to 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.

[0010] In a fixing rod according to one embodiment of the present invention, the reinforcing fiber layer, which is different from the fibers of the reinforcing fiber layer, is a fiber-reinforced resin, wherein 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.

[0011] In a fixing rod 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 is formed in a woven manner, with the fibers aligned in one direction, or with the fibers randomly oriented. Furthermore, in a fixing rod 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°.

[0012] In a fixing rod according to one embodiment of the present invention, if multiple layers are provided, each of which is either the same layer or a different layer, each layer is either the same layer or a different layer.

[0013] In a fixing rod according to one embodiment of the present invention, the fibers of the reinforcing fiber layer are long fibers.

[0014] In a fixing rod according to one embodiment of the present invention, the fiber content of the reinforcing fiber layer is 60% by weight or more.

[0015] In a fixing rod 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 0.25 mm. [Effects of the Invention]

[0016] According to the above embodiments of the present invention, it is possible to provide a fixing rod that reduces damage during screw fixing, has high rigidity and durability against deformation load, and significantly improves safety even when it breaks. [Brief explanation of the drawing]

[0017] [Figure 1] This figure shows a spinal fixation device 10 including a fixation rod according to one embodiment of the present invention. [Figure 2] This figure schematically shows a cross-section of a fixing rod according to one embodiment of the present invention, obtained by cutting it with a plane perpendicular to its central axis. [Figure 3] This figure schematically shows a cross-section of a fixing rod according to one embodiment of the present invention, obtained by cutting it with a plane perpendicular to its central axis. [Figure 4] This figure schematically shows a cross-section of a fixing rod according to one embodiment of the present invention, obtained by cutting it with a plane perpendicular to its central axis. [Figure 5] This figure schematically shows a cross-section of a fixing rod according to one embodiment of the present invention, obtained by cutting it with a plane perpendicular to its central axis.

Best Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the rod for a fixture according to the present invention will be specifically described with reference to the accompanying drawings. The same reference numerals are given to common components in the plurality of drawings throughout the plurality of drawings. Note that each drawing is not necessarily drawn at an exact scale for convenience of explanation.

[0019] FIG. 1 is a view showing a spinal fixture 10 including a rod 1 for a fixture according to an embodiment of the present invention. As shown in the figure, the spinal fixture 10 includes a plurality of screw members 18 (two screw members 18 in the illustrated example) fixed to the bones of the spine, and a plurality of rod fixing members 20 (two rod fixing members 20 in the illustrated example) provided with a concave portion 21 for receiving the rod for the fixture and a pressing member 22, which are attached to the screw members 18, and a rod 1 for the fixture inserted into the concave portion 21 of the plurality of rod fixing members 20 and fixed by the pressing member 22.

[0020] Next, referring to FIGS. 2, 3, and 4, the rod 1 for a fixture according to an embodiment of the present invention used for a spinal fixture 10 will be described. FIGS. 2, 3, and 4 show the rod 1 for a fixture shown in FIG. 1 as seen in the X-X cross section shown in the same figure. The rod 1 for a fixture according to an embodiment of the present invention, when viewed in cross section, has a reinforcing fiber layer 2 and a resin layer 3 (example shown in FIG. 2), a reinforcing fiber layer 4 different from the fibers of the reinforcing fiber layer (example shown in FIG. 3), or a reinforcing fiber layer 5 having fibers oblique to the fiber direction of the reinforcing fiber layer (example shown in FIG. 4), and a plurality of layers of these layers are alternately formed. Here, the reinforcing fiber layer 2, the resin layer 3 (example shown in FIG. 2), the reinforcing fiber layer 4 different from the fibers of the reinforcing fiber layer (example shown in FIG. 3), or the reinforcing fiber layer 5 having fibers oblique to the fiber direction of the reinforcing fiber layer (example shown in FIG. 4) 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 (that is, the layer may be formed such that there are both thin and thick portions). Also, the layer may be formed intermittently (that is, not only are there thin and thick portions of the layer thickness, but there may also be portions where the layer thickness is 0 intervening).

[0021] According to the rod 1 for a fixture according to an embodiment of the present invention, it is possible to provide a rod for a fixture that reduces breakage during screw fixation, has high rigidity and high durability against deformation loads, and also has significantly improved safety even at the time of fracture. In particular, at the time of fracture of the rod 1 for a fixture according to an embodiment of the present invention, 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 has been found that it is possible to reduce the reinforcing fiber layer from becoming spiky when the rod breaks, and as a result, significantly enhance the safety to the human body.

[0022] In a fixing rod 1 according to one embodiment of the present invention, the reinforcing fiber layer 2 is a fiber-reinforced resin, using carbon, glass, boron, SiC, or aramid as the fiber, and epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK as the resin. In this way, it is possible to increase the bending rigidity and strength of the fixing rod 1.

[0023] In a fixing 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.

[0024] In a fixing rod according to one embodiment of the present invention, the reinforcing fiber layer 4, which is different from the fibers of the reinforcing fiber layer 2, is a fiber-reinforced resin, and the fibers used are carbon, glass, boron, SiC, or aramid, and the resin used 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 strength of the fixing rod. The reason for using a reinforcing fiber layer different from the fibers of the reinforcing fiber layer is that by using different materials, different properties other than rigidity and strength, such as flexibility and vibration absorption, can be imparted.

[0025] In a fixing rod 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 may be formed in a woven manner with the fibers aligned in one direction or randomly oriented. Also, in a fixing rod 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°. By arranging an appropriate laminate configuration in this way, it is possible to achieve the target strength and rigidity.

[0026] In a fixing rod 1 according to one embodiment of the present invention, if multiple layers of any of the following are provided, such as a resin layer 3, a reinforcing fiber layer 4 with fibers different from those of the reinforcing fiber layer, or a reinforcing fiber layer 5 having fibers oblique to the fiber direction of the reinforcing fiber layer, each layer may be the same or different (the same applies hereinafter). For example, if two layers are provided, there may be two resin layers 3 (in this case, each layer will be the same), or two different layers may be provided, such as a resin layer 3 and a reinforcing fiber layer 4 with fibers different from those of the reinforcing fiber layer. If 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 laminated structure.

[0027] In a fixing rod 1 according to one embodiment of the present invention, the fibers of the reinforcing fiber layer 3 are configured to be long fibers. By making the fibers of the reinforcing fiber layer 3 long fibers in this way, it is possible to further increase the bending rigidity and strength.

[0028] Furthermore, in the fixing rod 1 according to one embodiment of the present invention, the fiber content of the reinforcing fiber layer 3 is configured to be 60% by weight or more. In this way, a fixing rod 1 with high rigidity and excellent durability can be formed by a fiber layer in which long fibers are densely concentrated.

[0029] In a fixing rod 1 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, for example, in the range of 0.02 mm to 0.25 mm. In this way, the density of the resin is made uniform, and variations in strength depending on the location can be reduced.

[0030] Next, a method for manufacturing a fixing rod 1 according to one embodiment of the present invention will be described. First, in step 1, one of the following layers is cut to a predetermined size: a reinforcing fiber layer 2, a resin layer 3, a reinforcing fiber layer 4 with fibers different from those of the reinforcing fiber layer, or a reinforcing fiber layer 5 having fibers oblique to the fiber direction of the reinforcing fiber layer (layer cutting step). Then, in step 2, each layer is stacked in a predetermined arrangement (layer stacking step). In step 3, it is set in a predetermined mold and molded under predetermined conditions (for example, a temperature of 140°C and a pressure of 0.1 to 0.5 MPa) (molding step). Next, in step 4, it is processed to the final shape and dimensions (processing step). In this way, a fixing rod 1 according to one embodiment of the present invention is formed.

[0031] The fixing rod 1 according to one embodiment of the present invention, formed in this manner, reduces damage during screw fixing, has high rigidity and durability against deformation loads, and provides a fixing rod that is significantly safe even when it breaks. In particular, it has been found that when the fixing rod 1 according to one embodiment of the present invention breaks, stress is concentrated in one of the layers: the resin layer sandwiched between the reinforcing fiber layers, 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. This reduces the formation of thorns in the reinforcing fiber layer when the rod breaks, and as a result, safety to the human body is significantly improved.

[0032] Finally, with reference to Figure 5, a fixing rod 1 according to another embodiment of the present invention used in the spinal fixing device 10 will be described. Figure 5 shows the fixing rod 1 shown in Figure 1 in the XX cross-section shown in the figure. In the fixing rod 1 according to one embodiment of the present invention, when viewed in cross-section, a reinforcing fiber layer 2, a resin layer 3, a reinforcing fiber layer 4 with fibers different from those of the reinforcing fiber layer, or a reinforcing fiber layer 5 having fibers oblique to the fiber direction of the reinforcing fiber layer are alternately formed in multiple layers, and a coating layer 6 is further formed on the outer surface of the fixing rod 1. The coating layer 6 may be, for example, the same resin as the layer used in the fixing rod 1 described above, but is not limited to these. In this way, it is possible to further reduce the spiky formation of the reinforcing fiber layer when the rod breaks, and as a result, safety to the human body can be further enhanced.

[0033] The dimensions, materials, and arrangements of each component described herein are not limited to those explicitly described in the embodiments, and each component can be modified to have any dimensions, materials, and arrangements that fall within the scope of the present invention. Furthermore, components not explicitly described herein may be added to the described embodiments, and some of the components described in each embodiment may be omitted. [Explanation of symbols]

[0034] 1. Rod for fixing device 2. Reinforced fiber layer 3. Resin layer 4. Reinforcement fiber layer different from the fibers of the reinforcement fiber layer 5. Reinforced fiber layer having fibers oriented obliquely to the fiber direction of the reinforced fiber layer. 6 Covering layer 10 Spinal fixation device 18 Screw component 20 Rod fixing member 21 Recess 22 Pressing member

Claims

1. A rod for fixing devices, A fixing rod characterized in that, when viewed in cross-section, multiple layers of reinforcing fiber layers and resin layers are formed alternately.

2. The rod for a fixing device according to claim 1, wherein the reinforcing fiber layer is a fiber-reinforced resin, and the fibers used are carbon, glass, boron, SiC, or aramid, and the resin used is epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK.

3. The fixing rod according to claim 1 or 2, wherein the resin of the resin layer is epoxy, phenol, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK.

4. The rod for a fastener according to any one of claims 1 to 3, wherein the reinforcing fiber layer is formed in a woven manner with the fibers aligned in one direction or randomly oriented.

5. The fixing rod according to any one of claims 1 to 4, wherein the fibers of the reinforcing fiber layer are long fibers.

6. The fixing rod according to any one of claims 1 to 5, wherein the fiber content of the reinforcing fiber layer is 60% by weight or more.

7. The fixing rod according to any one of claims 1 to 6, wherein 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 0.25 mm.

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