Rod for spinal fixation

Abstract

This invention provides a spinal fixation rod that is easier and more stable to use when fixed with a screw. In one embodiment of the invention, the fixation rod is held by a fastening member fastened to the spine. The fixation rod is formed by stacking multiple layers of fiber layers in a manner that overlaps radially when viewed in a cross-section perpendicular to the axial direction of the fixation rod. A marking portion is formed on the fixation rod to indicate the clamping location of the fastening member. This marking portion is configured to indicate that the clamping direction of the fastening member at the clamping location intersects the interlayer direction of the multiple fiber layers.

Description

Technical Field

[0001] This invention relates to a rod for use in fixation devices for stabilizing the spine. Background Technology

[0002] Previously, various rods for fixing the spine were known as fixation devices.

[0003] As a type of fixing rod, for example, Patent Document 1 discloses the following: multiple prepregs, particularly unidirectional prepregs, are used in the manufacture of the implant. These prepregs are pressurized and grouted together under pressure and heat. The prepregs are fiber-matrix-semi-finished products, and further, semi-finished products containing reinforcing fibers disposed in a plastic matrix. The reinforcing fibers are carbon fibers. The prepregs can exist, for example, in the form of strands, strips, or sheets. By pressurizing and grooving the prepregs under pressure and temperature, the prepregs are continuously fused together to form the final form of the implant. After pressurization and grooving, the prepregs form the body of the implant.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2024-546988

[0005] However, in the rod disclosed in Patent Document 1, there is room for improvement from the viewpoint of more stable and reliable use when the rod is fixed to the screw head.

[0006] One object of the present invention is to provide a fastener rod that is easier to use stably and reliably when fixed with a screw. Other objects of the present invention become apparent from the entirety of this specification. Summary of the Invention

[0007] In one embodiment of the present invention, a fastening rod is clamped by a fastening member fastened to the spine. The fastening rod is formed by stacking multiple fiber layers in a manner that overlaps radially when viewed in a cross section perpendicular to the axial direction of the fastening rod. A marking portion indicating the clamping position of the fastening member is formed on the fastening rod. The marking portion is configured to indicate that the clamping direction of the fastening member at the clamping position is a direction that intersects the interlayer direction of the multiple fiber layers.

[0008] In a fastener rod according to one embodiment of the present invention, the marking portion is formed as a display portion capable of determining the clamping portion or a shape portion capable of determining the clamping portion.

[0009] In a fastener rod according to one embodiment of the present invention, the display portion is a mark provided on the outer peripheral surface of the fastener rod.

[0010] In a fastener rod according to one embodiment of the present invention, the shaped portion is a clamping surface or a curved shape provided on the outer peripheral surface of the fastener rod.

[0011] In a fastener rod according to one embodiment of the present invention, the bending shape includes a shape bent into an arc.

[0012] Invention Effects

[0013] According to the above embodiments of the present invention, a fastener rod that is easier to use stably and reliably when the screw is fixed can be provided. Attached Figure Description

[0014] Figure 1 This is a diagram showing a spinal fixation member 10 that includes a fixation rod according to one embodiment of the present invention.

[0015] Figure 2 (a) is a schematic diagram showing a cross-section of the fastener of one embodiment of the invention cut with a plane perpendicular to its central axis. Figure 2 (b) is a schematic diagram showing a cross-section of the fastener of one embodiment of the invention cut with a plane perpendicular to its central axis. Figure 2 (c) is a schematic diagram showing a cross-section of the fastener rod of one embodiment of the present invention cut with a plane perpendicular to its central axis. Figure 2 (d) is a schematic diagram showing a cross-section of the fastener rod of one embodiment of the present invention cut with a plane perpendicular to its central axis.

[0016] Figure 3 Figure (a) is a diagram showing a spinal fixation member 10 including a fixation rod 1 according to one embodiment of the present invention. Figure 3 (b) is a schematic diagram (sectional view) showing the direction of the shear force acting on the fastener rod 1 of one embodiment of the present invention. Figure 3 (c) is a schematic diagram (sectional view) showing the interlayer direction (up and down in the illustrated example) and the direction of shear force of the fiber layer of the fastener rod 1 according to one embodiment of the present invention.

[0017] Figure 4 (a) is a diagram illustrating the marking portion of the fixing rod 1 according to one embodiment of the present invention. Figure 4 Figure (b) is a diagram illustrating another configuration of the marking portion of the fixing rod 1 according to one embodiment of the present invention. Figure 4 (c) is a diagram illustrating another configuration of the marking portion of the fixing rod 1 according to one embodiment of the present invention. Figure 4 (d) is a diagram illustrating another form of the marking portion of the fixing rod 1 according to one embodiment of the present invention.

[0018] Figure 5 (a) is a diagram illustrating the relationship between the interlayer direction (boundary direction) of the fiber layers in the fastener rod 1 according to one embodiment of the present invention and the clamping direction (pressing direction) of the pressing member 22 (not shown). Figure 5 (b) is a diagram illustrating the relationship between the interlayer direction (boundary direction) of the fiber layer in the fastener rod 1 of one embodiment of the present invention and the clamping direction (pressing direction) of the pressing member 22 (not shown).

[0019] Figure 6 (a) is a diagram illustrating the marking portion of the fixing rod 1 according to one embodiment of the present invention. Figure 6 (b) is a diagram illustrating the marking portion of the fixing rod 1 according to one embodiment of the present invention.

[0020] Label Explanation

[0021] 1: Fixing rod; 2: Reinforcing fiber layer (fiber layer); 2a: Interlayer direction (direction of boundary surface); 3: Resin layer; 4: Reinforcing fiber layer with fibers different from those of the reinforcing fiber layer; 5: Reinforcing fiber layer with fibers oblique to the fiber direction of the reinforcing fiber layer; 6: Covering layer; 7: Marking part; 10: Spine fixation member; 18: Screw member; 20: Rod fixing member; 21: Recess; 22: Pressing member. Detailed Implementation

[0022] Hereinafter, embodiments of the fastener rod of the present invention will be specifically described with reference to the accompanying drawings. Common structural elements are labeled with the same reference numerals in the various drawings. It should be noted that, for ease of explanation, the drawings are not necessarily shown at an exact scale.

[0023] Figure 1 This is a diagram illustrating a spinal fixation member 10 incorporating a fixation rod 1 according to one embodiment of the present invention. As shown, the spinal fixation member 10 includes: a plurality of screw members 18 (two screw members 18 in the illustrated example) fixed to the vertebrae; a plurality of rod fixing members 20 (two rod fixing members 20 in the illustrated example) mounted on the screw members 18, having a recess 21 for receiving the fixation rod 1 and a pressing member 22; and a fixation rod 1 inserted into the recess 21 of the plurality of rod fixing members 20 and fixed by the pressing member 22.

[0024] Next, refer to Figure 2 of (a) Figure 2 of (b) Figure 2 (c) Figure 2(d) will describe an example of a fixation rod 1 of one embodiment of the present invention used for a spinal fixation 10. Figure 2 of (a) Figure 2 of (b) Figure 2 (c) Figure 2 (d) are all observed from the XX cross section shown in the figure. Figure 1 The figure shows a cross-sectional view of the fastener rod 1. As shown, in one embodiment of the present invention, the fastener rod 1, when viewed in cross-section, incorporates a reinforcing fiber layer 2 and a resin layer 3 ( Figure 2 (Example shown), a reinforcing fiber layer 4 with fibers different from those of the reinforcing fiber layer 2. Figure 3 (Example shown) or a reinforcing fiber layer 5 having fibers that are oblique to the fiber direction relative to the reinforcing fiber layer 2 ( Figure 4 The example shown is formed by alternating multiple layers. This provides a fastener rod that reduces breakage during screw fastening, exhibits high rigidity and durability under deformation loads, and significantly improves safety even in the event of fracture. Specifically, when the fastener rod 1 of the embodiment of the present invention fractures, stress concentrates in any of the following layers: the resin layer sandwiched between the reinforcing fiber layers, the reinforcing fiber layer with fibers different from those of the reinforcing fiber layers, or the reinforcing fiber layer having fibers inclined relative to the fiber direction of the reinforcing fiber layers. This reduces the likelihood of the reinforcing fiber layers becoming spiky upon rod fracture, resulting in significantly improved safety for the human body.

[0025] In addition, such as Figure 2 As shown in (d), in the fastener rod 1 of one embodiment of the present invention, when viewed in cross-section, multiple layers are alternately formed of any one of the following: reinforcing fiber layer 2, resin layer 3, reinforcing fiber layer 4 with fibers different from those of the reinforcing fiber layer 2, or reinforcing fiber layer 5 having fibers oblique to the fiber direction of the reinforcing fiber layer 2. A covering layer 6 is also formed on the outer surface of the fastener rod 1. This covering layer 6 is, for example, made of the same material as the resin used in the layers of the fastener rod 1 described above, but is not limited thereto. This further reduces the likelihood of the reinforcing fiber layer becoming spiky when the rod breaks, thereby further improving safety for the human body.

[0026] Here, the reinforcing fiber layer 2 and resin layer 3 ( Figure 2 (Example shown), a reinforcing fiber layer 4 with fibers different from those of the reinforcing fiber layer 2. Figure 3 (Example shown) or a reinforcing fiber layer 5 having fibers that are oblique to the fiber direction relative to the reinforcing fiber layer 2 ( Figure 4In the example shown, any layer is formed to have a thickness of 0.01 mm to 0.25 mm, but the thickness of the layer can also vary depending on the location of the layer (i.e., the layer thickness can be formed to have thin portions or thick portions). Furthermore, the layer can also be formed intermittently (i.e., there can be not only thin portions but also thick portions, and there can also be portions with a thickness of 0). Additionally, the fastener rod 1 of one embodiment of the present invention can be formed by stacking multiple layers of reinforcing fiber layers 2 when viewed in cross-section, and is not intended to be limited to a particular method.

[0027] In one embodiment of the fastener rod 1 of the present invention, the reinforcing fiber layer 2 is a fiber-reinforced resin. The fibers used are carbon, glass, boron, SiC, or aromatic polyamide, and the resin used is epoxy resin, phenolic resin, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK. This allows for increased bending stiffness and higher strength of the fastener rod 1.

[0028] In the fastener rod 1 of one embodiment of the present invention, the resin of the resin layer 3 is epoxy resin, phenolic resin, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK or PEEK.

[0029] In one embodiment of the fastener rod 1 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. The fibers used are carbon, glass, boron, SiC, or aromatic polyamide, and the resin used is epoxy resin, phenolic resin, unsaturated polyester, PA, PC, PPSU, POM, PP, PE, ABS, PS, PAEK, or PEEK. This allows for increased bending stiffness and higher strength in the fastener rod. Furthermore, the reason for using a reinforcing fiber layer different from the fibers of the aforementioned reinforcing fiber layer is that by using different materials, different properties can be imparted beyond rigidity and strength, such as flexibility and vibration absorption.

[0030] Next, refer to Figure 3 The fixing method of the spinal fixation member 10 of the fixation member rod 1 according to one embodiment of the present invention and the mechanism of shear force generation will be explained. Figure 3 Figure (a) is a diagram showing a spinal fixation member 10 including a fixation rod 1 according to one embodiment of the present invention. Figure 3 (b) is a schematic diagram (sectional view) showing the direction of the shear force acting on the fastener rod 1 of one embodiment of the present invention. Figure 3(c) is a schematic diagram (sectional view) showing the interlaminar direction (vertical direction in the illustrated example) and the direction of shear force of the fiber layer of the fastener rod 1 according to one embodiment of the present invention. Figure 3 As shown in (a), the spinal fixation member 10 includes: a screw member 18 (one screw member 18 in the illustrated example) fixed to the bone of the spine; a rod fixing member 20 (one rod fixing member 20 in the illustrated example) mounted on the screw member 18, having a recess 21 for receiving the fixing rod 1 and a pressing member 22 (in the illustrated example, the pressing member 22 is composed of two parts); and a fixing rod 1 inserted into the recess 21 of the plurality of rod fixing members 20 and fixed by the pressing member 22. Here, the abutting surface of the pressing member 22 (at least one of the pressing members 22 in the case where the pressing member 22 is composed of two parts as shown in the illustrated example) that abuts against the outer surface of the fixing rod 1 can be formed in a shape along the shape of the outer surface of the fixing rod 1 (the outline of the outer surface), for example, the abutting surface can also be formed in an arc shape (the case of the abutting surface viewed from the side).

[0031] In addition, such as Figure 3 As shown in (b), in one embodiment of the present invention, when the fixing rod 1 is fastened to the screw member 18 of the spinal fixation member 10 (however, not shown), the fixing rod 1 is clamped by the pressing member 22, and the fixing rod 1 is in its clamping direction (in Figure 3 of (a) Figure 3 In example (b), the pressing force is applied by the pressing member 22 in the vertical direction (not shown, but the direction of extension of the screw member 18). Furthermore, as... Figure 3 As shown in (c), when the fixing rod 1 is subjected to the pressing force of the pressing member 22, a shear force is generated in the clamping direction (flattening direction) at the boundary region between the contact portion and the non-contact portion of the pressing member 22 (which contacts the fixing rod 1). If the direction of this shear force coincides with the interlayer direction (vertical direction in the illustrated example) 2a of the fiber layer of the fixing rod 1 in one embodiment of the present invention, the fixing rod 1 is easily damaged by this shear force.

[0032] Next, refer to Figures 4 to 6 The fixing rod 1 of one embodiment of the present invention will be further described. Figure 4 (a) is a diagram illustrating the marking portion of the fixing rod 1 according to one embodiment of the present invention. Figure 4 Figure (b) is a diagram illustrating another configuration of the marking portion of the fixing rod 1 according to one embodiment of the present invention. Figure 4 (c) is a diagram illustrating another configuration of the marking portion of the fixing rod 1 according to one embodiment of the present invention. Figure 4Figure (d) illustrates another configuration of the marking portion of the fixing rod 1 according to one embodiment of the present invention. Additionally, Figure 5 of (a) Figure 5 (b) is a diagram illustrating the relationship between the interlayer direction (boundary direction) of the fiber layers in the fastener rod 1 according to one embodiment of the present invention and the clamping direction (pressing direction) of the pressing member 22 (not shown). Furthermore, Figure 6 (a) is a diagram illustrating the marking portion of the fixing rod 1 according to one embodiment of the present invention. Figure 6 (b) is a diagram illustrating the marking portion of the fixing rod 1 according to one embodiment of the present invention.

[0033] like Figure 1 , Figure 4 As shown, in one embodiment of the present invention, the fixing rod 1 is a fixing rod 1 clamped by a fastening member (the rod fixing member 20 described above) that is fastened to the spine, which passes through a cross section perpendicular to the axial direction (extension direction) of the fixing rod 1. Figure 1 When observed at the XX cross section, the fastener is formed by stacking multiple fiber layers (reinforcing fiber layers) 2 in a radially overlapping manner on the fastener rod 1. A marking portion 7 is formed on the fastener rod 1 to indicate the clamping portion (pressing portion) of the fastening member (the rod fixing member 20 described above). (In the illustrated example, four forms are shown simultaneously: text, lines, triangles, and dotted lines indicating the display range; however, texture processing or matte processing can also be appropriately implemented.) This marking portion 7 is configured to indicate that the clamping direction of the fastener (the rod fixing member 20 described above) at the clamping portion intersects with the interlayer direction (the direction of the boundary surface described later) 2a of the multiple fiber layers 2. Here, as... Figure 5 of (a) Figure 5 As shown in (b), "interlayer direction of multiple fiber layers" refers to the direction (extension direction) of the boundary surface between two adjacent fiber layers (interlayer). Figure 5 In example (a), the left and right directions on the paper are considered. Figure 5 In example (b), the direction is from the top left to the bottom right of the paper surface. "Clamping direction" refers to the direction in which the clamping member 22 (not shown) clamps (presses) the fixing rod 1 (in the illustrated examples, this is the vertical direction of the paper surface). Additionally, "intersecting direction" refers to a direction where the clamping direction of the fastening member (the described rod fixing member 20) at the clamping location is not the same as the interlayer direction (boundary direction) of the multiple fiber layers 2 (e.g., Figure 5 of (a) Figure 5 (b) indicates the direction.

[0034] According to one embodiment of the present invention, a fastener rod 1 can be provided that is easier to use stably and reliably when the screw is fixed. More specifically, it is easier to grasp the clamping (fixing) position of the fastening member (the rod fixing member 20 described above) relative to the fastener rod 1, so not only is the operation of the operator easier, but the fastener rod 1 can be clamped (fixed) at a position where the interlayer direction (boundary direction) 2a of the stacked layers intersects (is offset) from the clamping direction. Therefore, the shear force of the interlayer (boundary direction) components of the stacked layers is reduced, thereby suppressing damage caused by shear.

[0035] In addition, such as Figure 4 , Figure 5 As shown, in a fastener rod 1 according to one embodiment of the present invention, the marking portion 7 is formed as a display portion capable of determining the clamping portion. Figure 4 of (a) Figure 4 of (b) Figure 4 (c) Figure 4 (Example shown in (d)) or the shape of the clamping part that can be determined (described later) Figure 6 of (a) Figure 6 (Example shown in (b)). Here, in the fastener rod 1 of one embodiment of the present invention, the display part is a mark provided on the outer peripheral surface of the fastener rod, as described above. Figure 4 In the manner shown in (a), Figure 4 Multiple axial lines as shown in (b) (axial lines of rod 1 for fixing). Figure 4 Multiple oblique lines as shown in (c) (lines inclined relative to the axial line of the fixing rod 1) Figure 4The markings can take various forms, such as multiple first oblique lines (lines inclined at a first angle relative to the axial line of the fixing rod 1) and multiple second oblique lines (lines inclined at a first angle relative to the axial line of the fixing rod 1), as shown in (d). Furthermore, various forms of markings for the display section can be considered, including solid lines, dotted lines, dashed lines, single lines, and multiple lines. Besides laser marking, stickers, colored paints (screen printing), etc., can also be used. Additionally, the markings for the display section can be applied to the fixing rod 1 itself (the outer surface of the fixing rod 1), or applied after covering the outer surface of the fixing rod 1, or applied to the fixing rod 1 itself (the outer surface of the fixing rod 1) in a manner that does not expose the surface, and then covered (in the case of "covering," transparent resin can be used for the covering). As for the raw materials used for the covering, thermoplastic PEEK resin, nylon, PP (polypropylene), etc., can be used, but are not limited to these. In this way, it becomes easier to grasp the clamping (fixing) position of the fastening component (the rod fixing component 20 described above) relative to the fixing rod 1. Therefore, not only does the operator's work become easier, but the fixing rod 1 can also be clamped (fixed) at a position where the interlayer direction (boundary direction) 2a of the stacked layers intersects (is offset) from the clamping direction. As a result, the shear force of the interlayer (boundary direction) 2a component of the stacked layers is reduced, thereby suppressing damage caused by shear.

[0036] In addition, such as Figure 6 of (a) Figure 6 As shown in (b), in a fastener rod 1 according to one embodiment of the present invention, the marking portion 7 is a shaped portion, which is a clamping surface provided on the outer peripheral surface of the fastener rod 1. Figure 6 (a) or curved shape Figure 6 (in case (b)). Furthermore, in the fixing rod 1 of one embodiment of the present invention, the bending shape is configured to include a shape bent into an arc. Thus, in Figure 6 In the case of a flat surface as shown in (a), by making the fixed position a flat surface, the fastening member (the rod fixing member 20 described above) can be stably clamped (fixed) by the rod 1. Furthermore, in Figure 6 In the case of the bending shape shown in (b), by clamping (fixing) towards the buckling direction, the direction of the shear force is offset from the clamping direction (the direction of the boundary surface), thus suppressing shear failure. Furthermore, since the fixing rod 1 is bent towards the stacking direction, the direction of the shear force acting by the fixing rod 1 swinging around the clamping part of the fastening member as a fulcrum is offset from the stacking direction, thereby suppressing the occurrence of failure caused by shear force. In particular, by continuously bending in an arc shape to offset the clamping direction, the occurrence of failure caused by a local increase in shear force can be suppressed. Here, in Figure 6In the example shown in (b), the case is illustrated based on the bending of a portion of the fastener rod 1, but it is also possible for the fastener rod 1 to be bent as a whole. According to one embodiment of the fastener rod 1 of the present invention, it is easy to grasp the clamping (fixing) position of the fastening member (the rod fixing member 20 described above) relative to the fastener rod 1. Therefore, not only is the operation of the operator easier, but the fastener rod 1 can also be clamped (fixed) at a position where the interlayer direction (boundary surface direction) of the stacked layers intersects (is offset) from the clamping direction. Therefore, the shear force of the interlayer (boundary surface direction) components of the stacked layers is reduced, thereby suppressing damage caused by shear.

[0037] The dimensions, materials, and configurations of the structural elements described in this specification are not limited to those explicitly described in the embodiments. These structural elements can be modified to have any dimensions, materials, and configurations that fall within the scope of this invention. Furthermore, structural elements not explicitly described in this specification can be added to the described embodiments, and some structural elements described in each embodiment can be omitted.

Claims

1. A rod for fixing a component, which is clamped by a fastening member fastened to the spine, characterized in that, The fastener rod is formed by stacking multiple fiber layers in a manner that overlaps radially when viewed in a section perpendicular to the axial direction of the fastener rod. The fastener has a marking on its rod indicating the clamping portion of the fastening component. The marking portion is configured to indicate that the clamping direction of the fastening member at the clamping location is a direction that intersects with the interlayer direction of the plurality of fiber layers.

2. The rod for fixing according to claim 1, wherein, The marking portion is formed as a display portion capable of determining the clamping portion or a shape portion capable of determining the clamping portion.

3. The rod for fixing according to claim 2, wherein, The display section is a mark provided on the outer peripheral surface of the fixing rod.

4. The rod for fixing according to claim 2, wherein, The shaped portion is a clamping surface or a curved shape provided on the outer peripheral surface of the fixing member rod.

5. The rod for fixing according to claim 4, wherein, The curved shape includes a shape that is curved into an arc.

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