Headpin

Abstract

To provide a head pin which has excellent disposability and can reduce an artifact.SOLUTION: A head pin can fix a head of an animal and includes: a body part of the head pin having first reinforced plastic including 30 wt.% to 70 wt.% first reinforced fiber and 30 wt.% to 70 wt.% first resin; and an end part of the head pin which is fixed to an end of the body part, can contact the head, and includes at least one of metal, ceramics, cermet and second reinforced plastic.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a head pin capable of fixing an animal's head.

Background Art

[0002] In surgeries in fields such as neurosurgery, head pins including tip portions that pierce the head have been developed to fix the head of an animal (particularly, a human) (see Patent Document 1).

[0003] Conventionally, in order to maintain the strength of fixing the head, a head pin has been proposed in which the tip portion of the head pin made of metal (such as stainless steel) substantially entirely is sapphire. Also, in order to maintain the hygiene of the tip portion of the head pin that invades the living body, a head pin has been proposed in which a cap made of metal or the like is attached to and detached from the tip portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, a head pin made of metal (such as stainless steel) substantially entirely causes artifacts when imaging a medical image of the head, and becomes an obstacle when performing a surgery or the like while checking the medical image. Also, a sapphire head pin not only cannot reduce artifacts but is expensive, and thus is unsuitable as a disposable head pin. Further, a cap made of metal or the like that is attached to and detached from the tip portion is excellent in disposability, but since it is necessary to widely cover the invasive portion, artifacts caused by the cap made of metal or the like cannot be reduced.

Means for Solving the Problems

[0006] The head pin of the present invention is a head pin capable of fixing the head of an animal, comprising: a body of the head pin having a first reinforcing plastic comprising 30% to 70% by weight of a first reinforcing fiber and 30% to 70% by weight of a first resin; and a tip of the head pin fixed to the tip of the body and capable of contacting the head, comprising at least one of metal, ceramics, cermet, and second reinforcing plastic. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a head pin that is highly disposable and can reduce artifacts. [Brief explanation of the drawing]

[0008] [Figure 1] These are a side view and a front view of the head pin of this embodiment. [Figure 2] This is a perspective view of the head pin of this embodiment. [Figure 3] This table shows experimental results regarding compressive strength and the presence or absence of internal cavities when the composition ratio (weight %) of reinforcing fibers and resin in the body is changed. [Figure 4] This diagram illustrates the formation of internal cavities. [Figure 5] This figure shows examples of the shape and size of the tip. [Figure 6] This figure shows the results of an experiment in which a head pin was thrust into a simulated bone. [Figure 7] This figure shows artifacts from conventional head pins. [Figure 8] This figure shows the artifacts of the head pin in this embodiment. [Figure 9] This is a table evaluating head pin artifacts. [Figure 10] These are a side view, a front view, and a perspective view of the head pin of this embodiment. [Modes for carrying out the invention]

[0009] Firstly, the inventors have found a composition ratio of reinforcing fibers and resin that provides both appropriate compressive strength and low artifacts for a head pin capable of securing an animal's head. Secondly, the inventors have found at least one material, shape, and size for the tip of the head pin that provides both reliable head fixation and low artifacts, by using a high-strength material for the tip of the head pin, which requires particular strength to securely fix the head.

[0010] According to this embodiment, a head pin that achieves low artifacts can be provided. Furthermore, since the head pin according to this embodiment has reinforcing fibers and resin as its main composition, it can be easily mass-produced by injection molding using a mold, and a head pin that is inexpensive and has excellent disposability can be provided.

[0011] The head pin of this embodiment will be described with reference to the drawings. Figure 1 is a side view and a front view of the head pin of this embodiment. Figure 2 is a perspective view of the head pin of this embodiment.

[0012] As shown in Figures 1 and 2, the head pin 100 comprises a body portion 10 (shaft portion 1 and tapered portion 2) and a tip portion 3. The tip portion 3 is fixed to the tip of the body portion 10.

[0013] Figure 3 is a table showing experimental results regarding compressive strength and the presence or absence of internal cavities when the composition ratio (weight %) of reinforcing fibers (1 mm carbon fibers) and resin (vinyl ester) of the body 10 is changed. Since the body 10 is mainly composed of reinforcing fibers and resin, it is possible to achieve low artifacts, but appropriate compressive strength is necessary.

[0014] The experimental results showed that compressive strength increased as the composition ratio of reinforcing fibers increased. This indicates that compressive strength depends on the composition ratio of reinforcing fibers. Furthermore, as shown in Figure 4(a), it was found that internal cavities formed as the composition ratio of resin increased. This indicates that internal cavities depend on the composition ratio of resin. In fact, as shown in Figure 4(b), it was confirmed that internal cavities formed in a head pin made only of resin.

[0015] In Experiment Nos. 1 and 2, there is sufficient compressive strength of 2700 N and 3000 N or more respectively. However, due to the high resin composition ratio, internal cavities occur, so the performance as a head pin cannot be guaranteed. That is, depending on the position and shape of the internal cavities, there is a risk that the compressive strength as a head pin cannot be obtained. Therefore, from the experimental results, it is appropriate that the resin composition ratio is 70% by weight or less.

[0016] In Experiment Nos. 3 and 4, there is sufficient compressive strength of 2700 N and 3000 N or more respectively, and no internal cavities occur. Therefore, in order to obtain the compressive strength as a head pin, the body portion 10 requires a composition ratio of reinforcing fibers (first reinforcing fibers) of 30% by weight or more.

[0017] On the other hand, when the composition ratio of the reinforcing fibers (first reinforcing fibers) is 30% by weight or more and the composition ratio of the resin is 70% by weight or less, it is possible to increase the compressive strength while preventing internal cavities in the body portion 10. However, when the composition ratio of the resin becomes less than 30% by weight, the viscosity becomes insufficient when injection molding the body portion 10, and injection molding cannot be successfully performed.

[0018] Therefore, the composition ratio of the body portion 10 that can obtain sufficient compressive strength and is suitable for injection molding is that the first reinforcing fibers are 30% to 70% by weight and the resin is 30% to 70% by weight. Since the reinforcing fibers are more expensive than the resin, in order to provide a head pin that is cheaper and has excellent disposability, preferably, the composition ratio of the body portion 10 is that the first reinforcing fibers are 30% to 50% by weight and the resin is 50% to 70% by weight.

[0019] Thus, the body 10 has a first reinforcing plastic containing 30% to 70% by weight of first reinforcing fibers and 30% to 70% by weight of first resin. The first reinforcing plastic is preferably carbon fiber reinforced plastic, but sufficient compressive strength of the body 10 can be obtained even if it is at least one of glass fiber reinforced plastic, carbon fiber reinforced plastic, boron fiber reinforced plastic, aramid fiber reinforced plastic, Kevlar fiber reinforced plastic, Dyneema fiber reinforced plastic, and Zylon fiber reinforced plastic. Furthermore, since the internal void and viscosity during injection molding depend on the composition ratio of the resin, the composition ratio of the body 10 is the same as that of carbon fiber even if these reinforcing fibers are used. Generally speaking, the strength increases as the length of the reinforcing fibers in the composition increases. In the experiment shown in Figure 3, 1 mm carbon fibers were used, but it has been found that sufficient strength can be obtained even if carbon fibers of 0.5 mm to 5 mm are used.

[0020] The tip portion 3 is capable of contacting the animal's head and, preferably, is capable of piercing the animal's head in order to provide a head pin that securely fixes the head. Since the tip portion 3 is subjected to particular force, a higher compressive strength than that of the body portion 10 is required. In this case, the higher compressive strength than that of the body portion 10 depends on at least one of the material, shape, and size of the tip portion 3.

[0021] Furthermore, artifacts caused by the tip 3 depend on at least one of the material, shape, and size of the tip 3. For example, if the material of the tip 3 is reinforcing fiber, low artifacts can be achieved regardless of shape and size. If the material of the tip 3 is metal, artifacts are more likely to occur, but low artifacts can be achieved by selecting an appropriate shape and size.

[0022] First, the material of the tip portion 3 is a material that includes at least one of metal, ceramics, cermet, and a second reinforced plastic.

[0023] To securely fix the head, the material of the tip 3 is preferably at least one of metal, ceramics, and cermet. Furthermore, to reduce artifacts, the material of the tip 3 is preferably reinforced plastic.

[0024] Next, the shape and size of the tip portion 3 is preferably a shape that includes at least one of the shapes of a substantially cone, a substantially frustum, and a substantially solid of revolution, and in order to reduce artifacts, the maximum length of the base of the shape is preferably 1.5 mm to 3 mm.

[0025] Note that the size of the tip section 3 is set based on metals that are prone to generating artifacts; artifacts are further reduced with other materials.

[0026] Figure 5 shows examples of the shape and size of the tip sections. The material is metal (titanium). In Figure 5, the tip sections 3-1, 3-2, and 3-3 include approximately conical (approximately solid of revolution) bodies 30-1, 30-2, and 30-3, with the base lengths of the approximately conical (approximately solid of revolution) bodies 30-1, 30-2, and 30-3 being 1 mm, 2 mm, and 3 mm, respectively.

[0027] Furthermore, the tip portions 3-1, 3-2, and 3-3 include projections 31-1, 31-2, and 31-3 that extend toward the body portion 10, and the projections 31-1, 31-2, and 31-3 are embedded in the body portion 10, thereby enabling the tip portions 30-1, 30-2, and 30-3 to be fixed to the body portion 10.

[0028] Although the projections 31-1, 31-2, and 31-3 in Figure 5 are cylindrical in shape, the projections 31 may include at least one of the following shapes: tapered, threaded, flanged, and arrowhead-shaped, in order to increase the fixing strength when fixed to the body 10. Preferably, the projections 31 are flanged in shape to further increase the fixing strength when fixed to the body 10. Also, preferably, the projections 31 are threaded in shape in order to make the projections 31 detachable from the body 10 and to provide a more inexpensive and disposable head pin. In this case, the embedded hole (not shown) in the body 10 has a shape that screws into the threaded projection 31.

[0029] Figure 6 shows the experimental results of thrusting a head pin, equipped with the titanium tips 30-1, 30-2, and 30-3 shown in Figure 5, into a simulated bone. The projections (not shown) of the tips 30-1, 30-2, and 30-3 extend toward the body 10 and are embedded in the body 10. Figure 6 shows the results of thrusting tip 3 into the simulated bone by applying forces of 27.2 kg (60 lbs) and 54.4 kg (120 lbs) to the head pin.

[0030] Figure 6(a) shows the experimental results when a head pin equipped with tip 30-1 was thrust into a simulated bone. Under both load conditions, tip 30-1 penetrated the simulated bone and demonstrated sufficient compressive and fixation strength.

[0031] Figure 6(b) shows the experimental results when a head pin equipped with tip 30-2 was thrust into a simulated bone. Under both load conditions, tip 30-2 penetrated the simulated bone and demonstrated sufficient compressive and fixation strength.

[0032] Figure 6(c) shows the experimental results of inserting a head pin equipped with tip 30-3 into a simulated bone. Before reaching a load of 27.2 kg (60 pounds), the tip of tip 30-2 bent, failing to demonstrate sufficient compressive and fixing strength.

[0033] Although not shown in Figure 6, a similar experiment was conducted on tip 3 that includes a roughly conical (roughly revolutionary) shape, with a base length of 1.5 mm. The results showed that, under both load conditions, tip 30-2 penetrated the simulated bone and demonstrated sufficient compressive and fixing strength.

[0034] Therefore, experimental results indicate that in order to obtain sufficient compressive strength and fixing strength at the tip portion 3, the length of the base of the approximately conical (approximately revolutionary) body should be 1.5 mm or more.

[0035] Next, we present the results of artifact evaluation experiments using head pins with base lengths of 1 mm, 1.5 mm, 2 mm, and 3 mm for the approximately conical (approximately revolutionary) shapes contained in tip 3.

[0036] Figure 7 shows artifacts from a conventional head pin. Figure 8 shows artifacts from the head pin of this embodiment. Each head pin was fixed in three places to a phantom modeled after an animal's head, and CT images (cone-beam CT images) were acquired.

[0037] Figure 7(a) shows artifacts in a stainless steel head pin. Figure 7(b) shows artifacts in a sapphire head pin. Figure 7(c) shows artifacts in a head pin with a stainless steel cap attached to the tip.

[0038] Figure 8(a) shows artifacts caused by a head pin with a base length of 1 mm in the roughly conical (roughly revolutionary) shape contained in tip 3. Figure 8(b) shows artifacts caused by a head pin with a base length of 1.5 mm in the roughly conical (roughly revolutionary) shape contained in tip 3. Figure 8(c) shows artifacts caused by a head pin with a base length of 2 mm in the roughly conical (roughly revolutionary) shape contained in tip 3. Figure 8(d) shows artifacts caused by a head pin with a base length of 3 mm in the roughly conical (roughly revolutionary) shape contained in tip 3.

[0039] Figure 9 shows a table evaluating the artifacts of each head pin. In the CT image in Figure 7, artifacts radiated from the tip of the head pin, resulting in low evaluations of C and B. In the CT image in Figure 8, the longer the length of the base of the approximately cone (approximately solid of revolution) contained in tip 3, the more artifacts radiated from the tip of the head pin, but the evaluation was A. + ,A,A - It was very high. The rating was A. - It is permissible up to this point.

[0040] Therefore, considering sufficient compressive strength and fixing strength of the tip portion 3, the length of the base of the approximately conical (approximately revolutionary) contained in the tip portion 3 is 1.5 mm or more, and considering low artifacts, the length of the base of the approximately conical (approximately revolutionary) contained in the tip portion 3 is 3 mm or less. Considering the balance between sufficient compressive strength and fixing strength of the tip portion 3 and low artifacts, it is preferable that the length of the base of the approximately conical (approximately revolutionary) contained in the tip portion 3 is 1.5 mm or more and 2.5 mm or less. Furthermore, it is preferable that the length of the base of the approximately conical (approximately revolutionary) contained in the tip portion 3 is 1.5 mm or more and 2 mm or less.

[0041] In addition to titanium, the tip portion 3 may also contain at least one of the following metals: stainless steel, iron, nickel, cobalt, and cemented carbide.

[0042] Although embodiments of the present invention have been described above, the present invention is not limited thereto and can be modified or altered within the scope described in the claims.

[0043] For the same reasons as the first reinforced plastic, the second reinforced plastic may be any reinforced plastic containing 30% to 70% by weight of second reinforcing fibers and 30% to 70% by weight of second resin. Preferably, the second reinforced plastic is a reinforced plastic with higher compressive strength than the first reinforced plastic. Therefore, preferably, the second reinforced plastic is a reinforced plastic containing 50% to 70% by weight of second reinforcing fibers and 30% to 50% by weight of second resin. Also, similar to the first reinforced plastic, the second reinforced plastic is preferably a carbon fiber reinforced plastic, but other reinforced plastics may also be used.

[0044] Furthermore, the resin includes at least one of a thermosetting resin and a thermoplastic resin. For example, the resin may be selected from epoxy-based, phenol-based, and unsaturated polyester-based resins.

[0045] Furthermore, the tip portion 3 may have the shape shown in Figure 10. 。 [Industrial applicability]

[0046] This invention is useful as a head pin that offers excellent disposability and reduces artifacts. [Explanation of Symbols]

[0047] 1... Shaft 2... Tapered section 3,30...Tip 10...Body part 31...Protrusion 100... Headpin

Claims

1. A head pin capable of securing the head of an animal, The head pin body comprises a first reinforced plastic (where the sum of the first reinforced fibers and the first resin is 100% by weight) containing 30% to 70% by weight of first reinforcing fibers and 70% to 30% by weight of first resin, and the body of the head pin does not have an internal cavity. The tip of the head pin is fixed to the tip of the body and is capable of contacting the head, and includes at least one of metal, ceramics, cermet, and a second reinforced plastic, Equipped with, The head pin is characterized in that the first reinforcing fiber is a carbon fiber having a length of 1 mm to 5 mm.

2. The head pin according to claim 1, wherein the second reinforced plastic is a reinforced plastic comprising 30% to 70% by weight of second reinforcing fibers and 70% to 30% by weight of second resin (provided that the sum of the second reinforcing fibers and the second resin is 100% by weight), and the second reinforcing fibers are carbon fibers having a length of 1 mm to 5 mm.

3. The head pin according to claim 1 or 2, characterized in that the reinforced plastic is carbon fiber reinforced plastic.

4. The head pin according to any one of claims 1 to 3, characterized in that the resin comprises at least one of a thermosetting resin and a thermoplastic resin.

5. The head pin according to any one of claims 1 to 3, characterized in that the resin is a vinyl ester.

6. The head pin according to any one of claims 1 to 5, characterized in that the tip portion includes at least one of stainless steel, titanium, iron, nickel, cobalt, and cemented carbide as the metal, and includes at least one shape of a substantially cone, a substantially frustum, or a substantially revolutionary body, and the maximum length of the base of the shape is 1.5 mm to 3 mm.

7. The head pin according to any one of claims 1 to 6, characterized in that the tip portion includes at least one of zirconia, alumina, silicon carbide, silicon nitride, sialon, cordierite, ferrite, barium titanate, lead zirconate titanate, forsterite, zircon, mullite, steatite, and aluminum nitride as the ceramic material, and includes at least one shape of a substantially cone or substantially frustum, and the maximum length of the base of at least one of the substantially cone or substantially frustum is 1.5 mm to 3 mm.

8. The head pin according to any one of claims 1 to 7, wherein the tip portion includes carbon fiber reinforced plastic as the second reinforced plastic, and includes at least one shape of a substantially cone, a substantially frustum, or a substantially revolutionary body, and the maximum length of the base of at least one of the substantially cone, the substantially frustum, or the substantially revolutionary body is 1.5 mm to 3 mm.

9. The aforementioned tip portion includes a projection that extends toward the body portion, The head pin according to any one of claims 1 to 8, characterized in that the projection is embedded in the body so that the tip can be fixed to the body.

10. The head pin according to claim 9, characterized in that the projection includes at least one of the following shapes: cylindrical, tapered, threaded, flanged, and arrowhead.

Images