Pin, drill bit and kit

Abstract

The pin is melted by receiving ultrasonic vibration from the ultrasonic welding device. The pin is made of a bioabsorbable material. The pin has a shaft portion and a head portion. The shaft portion includes a first end portion and a second end portion in an axial direction. The head portion is formed at the first end portion. A diameter of the head portion is greater than a diameter of the shaft portion at the first end portion. A taper in which the diameter of the shaft portion decreases from the first end portion to the second end portion is formed in the shaft portion.

Description

Technical Field

[0001] This invention relates to pins, drill bits, and kits. Background Technology

[0002] Japanese Patent No. 4412901 (Patent Document 1) discloses an implant that is inserted via an implantation device. The implantation device has an oscillator and an oscillation unit. The oscillation unit is used to hold the implant. The oscillation unit is excited by energy generated by the oscillator, thereby generating vibration. The implant receives the mechanical vibration from the oscillation unit and melts (see Patent Document 1).

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent No. 4412901 Summary of the Invention

[0004] The technical problem that the invention aims to solve For example, when ultrasonic vibrations are transmitted to a pin made of bioabsorbable material using the implantation device disclosed in Patent Document 1, frictional heat is generated, causing the pin to melt. This melting of the pin is then used to weld the pin to the hole. In this specification, "melting" includes melting that occurs when the temperature of the object rises above its melting point, and a "transition to a rubbery state" that occurs when the temperature of the object rises above its glass transition temperature but below its melting point.

[0005] For example, if frictional heat concentrates near the neck of the pin, the bioabsorbent material constituting the pin cannot fully penetrate the hole, potentially leading to accumulation of the bioabsorbent material (hereinafter referred to as "accumulation"). Furthermore, if frictional heat concentrates near the neck of the pin, the neck of the pin may break (hereinafter referred to as "neck breakage").

[0006] This invention was made to solve such problems, and its purpose is to provide a pin, drill bit, and kit that can suppress accumulation and neck breakage.

[0007] Technical means for solving technical problems In one aspect of the invention, a pin is melted by receiving ultrasonic vibrations from an ultrasonic welding device. The pin is made of a bioabsorbable material. The pin has a shaft portion and a head. The shaft portion includes a first end and a second end in the axial direction. The head is formed at the first end. The diameter of the head is larger than the diameter of the shaft portion at the first end. A tapered shape is formed on the shaft portion, with the diameter of the shaft portion decreasing from the first end to the second end.

[0008] The pin's shaft portion is tapered, with its diameter decreasing from the first end to the second end. For example, when a portion of the pin's shaft portion is inserted into a hole having the same tapered shape as the pin, the outer circumferential surface of the shaft portion contacts the inner circumferential surface of the hole. In this state, if the pin is subjected to ultrasonic vibration, the ultrasonic waves tend to concentrate at the portion of the shaft portion that contacts the hole. Therefore, using this pin, when the pin is subjected to ultrasonic vibration, frictional heat is concentrated at the portion of the shaft portion that contacts the hole, and not at the junction of the shaft portion and the head (neck), thus suppressing buildup and neck breakage.

[0009] In the aforementioned pin, the head may include a head body portion and a stepped portion. The stepped portion may be formed between the head body portion and the first end portion. The diameter of the stepped portion at the head body portion side end portion may be smaller than the diameter of the head body portion, and the diameter of the stepped portion at the first end portion side end portion may be larger than the diameter of the shaft portion at the first end portion.

[0010] The aforementioned pin can be formed by passing through a hole formed in the plate. The diameter of the hole can be greater than the diameter of the stepped portion at the end of the head body portion but less than the diameter of the head body portion. The length of the stepped portion in the axial direction can be greater than or equal to the length of the aforementioned hole in the axial direction.

[0011] In this pin, the length of the axially stepped portion is greater than the length of the axially oriented hole in the plate. Therefore, using this pin, the lower surface of the head body hardly presses against the plate, and the propagation of ultrasonic vibration to the plate is suppressed, thus suppressing plate deterioration caused by ultrasonic vibration.

[0012] The pin can be configured to be inserted into a hole formed in an animal bone. The hole can be formed by inserting a drill tip into the bone. The drill tip can be tapered with a diameter decreasing towards the front end. Before receiving ultrasonic vibrations from an ultrasonic welding device, only a portion of the pin's shaft can be inserted into the hole. The axial length of the portion of the shaft can be more than 20% of the axial length of the entire shaft.

[0013] In this pin, before receiving ultrasonic vibrations from the ultrasonic welding device, only a portion of the shaft can be inserted into the bone cavity, and the axial length of this portion is more than 20% of the total axial length of the shaft. Using this pin, even before receiving ultrasonic vibrations from the ultrasonic welding device, a portion of the shaft can be inserted into the bone cavity. After the pin stabilizes, the ultrasonic vibrations propagate to the pin, thus preventing adverse effects such as applying oblique forces to the pin. As a result, this pin can suppress the occurrence of bone fragmentation and neck breakage.

[0014] In the aforementioned pins, the volume of the shaft portion can be more than 110% of the volume of the aforementioned hole.

[0015] Using this pin, the volume of the shaft is more than 110% of the volume of the hole, which can fully fill the hole with bio-absorbent material, thus making the pin welded firmly.

[0016] Another aspect of this invention relates to a drill bit configured to form a hole for inserting the aforementioned pin. The drill bit has a drill tip and a drill body. The drill body includes an electric motor that drives the rotation of the drill tip. A tapered shape is formed at the drill tip, with the diameter of the drill tip decreasing towards the front end.

[0017] The drill bit has a tapered tip whose diameter decreases towards the front end. Therefore, this drill bit can be used to create a tapered hole suitable for the insertion of the aforementioned pin.

[0018] Another aspect of the kit of the present invention includes the aforementioned pin and the aforementioned drill bit.

[0019] Using this kit, when the pin is welded into the hole formed by the drill bit, the frictional heat is concentrated on the part of the pin shaft that contacts the hole, and the frictional heat is not concentrated on the neck of the pin, thus suppressing the occurrence of build-up and neck breakage.

[0020] Invention Effects According to the present invention, a pin, drill bit, and kit are provided that can suppress accumulation and neck breakage. Attached Figure Description

[0021] Figure 1 It is a schematic diagram representing the plane of the pin.

[0022] Figure 2 It is a schematic representation Figure 1 Diagram of section II-II.

[0023] Figure 3 It is a schematic diagram representing the plane of the board.

[0024] Figure 4 It includes schematic representations Figure 3 The diagram shows the IV-IV section and a partially enlarged view.

[0025] Figure 5 It is a schematic diagram showing the state of a pin inserted into a hole in a plate.

[0026] Figure 6 It is a diagram that schematically illustrates the structure of a drill bit.

[0027] Figure 7It is a schematic diagram showing the state of a pin being inserted into a hole made in the bone by a drill bit.

[0028] Figure 8 This is a schematic diagram illustrating the structure of an ultrasonic welding device.

[0029] Figure 9 It is a schematic representation of a three-dimensional diagram of a tip.

[0030] Figure 10 This diagram schematically illustrates the installation of a pin on the protrusion at the tip.

[0031] Figure 11 This diagram illustrates how the pin welding is performed.

[0032] Figure 12 This diagram illustrates why the pins of the objects being compared tend to accumulate.

[0033] Figure 13 This diagram illustrates why the pins of the objects being compared are prone to neck breakage.

[0034] Figure 14 This diagram illustrates why the pins in the implementation method are less prone to piling up and neck breakage. Detailed Implementation

[0035] The following detailed description of one aspect of an embodiment of the present invention (hereinafter also referred to as "this embodiment") is provided with reference to the accompanying drawings. In the drawings, the same or corresponding parts are labeled with the same symbols and will not be described again. Furthermore, in the drawings, for ease of understanding, objects have been appropriately omitted or exaggerated and are presented as schematic diagrams.

[0036] [1. Composition] <1-1. The Structure of a Pin> Figure 1 This is a schematic diagram showing the plane of the pin 100 in this embodiment. Figure 2 It is a schematic representation Figure 1 The diagram shows section II-II. The pin 100 is subjected, for example, to an ultrasonic welding device 10 described later (see reference). Figure 8 The pin 100 is melted by ultrasonic vibration. That is, the ultrasonic welding device 10 is configured to melt the pin 100 by transmitting ultrasonic vibration to the pin 100, thereby welding the pin 100.

[0037] The pin 100 is made of a bioabsorbable material, for example, fused to human bone. For example, a plate 200 (see reference) would be positioned across the fracture site. Figure 3The plate 200 is fixed to the bone for fracture treatment. Multiple holes H1 are provided on the plate 200 for inserting pins 100. A drill bit 300 (see reference) is used on the bone. Figure 6 Holes are formed at positions corresponding to the holes H1 in the plate 200. Each pin 100, inserted into both the holes H1 in the plate 200 and the holes formed in the bone, is welded to the bone using an ultrasonic welding device 10, thereby fixing the plate 200, positioned across the fracture site, to the bone. The pins 100 can be used, for example, for the following applications.

[0038] The pin 100 preferably has high tensile strength. Therefore, it is preferable that no accumulation or necking occurs during the welding of the pin 100. The pin 100 of this embodiment has structural features that make it less prone to accumulation and necking during the welding of the pin 100. The structure of the pin 100 will be described in detail below.

[0039] Reference Figure 1 and Figure 2 The pin 100 includes a shaft portion 110 and a head 120. The shaft portion 110 extends downward from the lower surface of the head 120. In top view, the shaft portion 110 has a circular shape. In side view, the shaft portion 110 has a trapezoidal shape. The radial length L4 of the upper end of the shaft portion 110 is greater than the radial length L5 of the lower end of the shaft portion 110. The shaft portion 110 has a cross-sectional diameter that decreases from top to bottom. That is, the shaft portion 110 forms a tapered shape with its diameter decreasing from the upper end to the lower end. The angle formed by the central axis of the shaft portion 110 and the outer peripheral surface of the shaft portion 110 is θ1. θ1 is greater than 0°. θ1 is preferably 3° to 20°, more preferably 5° to 10°. Furthermore, the shape of the shaft portion 110 in top view may not be a perfect circle. For example, the shape of the shaft portion 110 in top view may be elliptical or polygonal.

[0040] A head 120 is formed at the upper end of the shaft portion 110. The head 120 includes a head body portion 122 and a stepped portion 124. The head body portion 122 has a generally cylindrical shape. When viewed from above, the head body portion 122 has a perfectly circular shape. The outer periphery of the lower surface portion of the head body portion 122 has rounded corners (R). Alternatively, the shape of the head body portion 122 when viewed from above may not be perfectly circular. For example, the shape of the head body portion 122 when viewed from above may be elliptical or polygonal.

[0041] A stepped portion 124 is formed between the shaft portion 110 and the head body portion 122. The stepped portion 124 has a cylindrical shape. When viewed from above, the stepped portion 124 has a perfect circular shape. However, the shape of the stepped portion 124 may not be perfectly circular when viewed from above. For example, the shape of the stepped portion 124 when viewed from above may be elliptical or polygonal. The radial length L2 of the stepped portion 124 is less than the radial length L1 of the head body portion 122, and greater than the radial length L4 of the upper shaft portion 110. Furthermore, the radial length L2 and the axial length L3 of the stepped portion 124 are influenced by the shape of the plate 200. A detailed description follows.

[0042] Figure 3 It is a schematic diagram showing the plane of plate 200. Figure 4 It includes schematic representations Figure 3 A diagram of section IV-IV, and a partially enlarged view. (Refer to...) Figure 3 and Figure 4 The plate 200 is a plate-shaped component made of a bioabsorbable material. The plate 200 has multiple recesses C2. In this example, the multiple (four) recesses C2 are arranged in a row. Each of the multiple recesses C2 is recessed from the upper surface F1 to the lower surface F2 of the plate 200. An inner flange 202 extending radially inward is formed on the lower surface of each of the multiple recesses C2. A hole H1 is formed in the center of each of the multiple recesses C2.

[0043] The radial length L6 of each hole H1 is less than the radial length L8 of each recess C1. The radial length L6 of each hole H1 is greater than the radial length L2 of the stepped portion 124 of the pin 100 (refer to...). Figure 2 That is, the radial length L2 of the stepped portion 124 is less than the radial length L6 of each hole H1. Furthermore, the radial length L6 of each hole H1 is less than the radial length L1 of the head body portion 122 of the pin 100. That is, the radial length L1 of the head body portion 122 is greater than the radial length L6 of each hole H1. The axial length L7 of each hole H1 (the thickness of the inner flange portion 202) is less than or equal to the axial length L3 of the stepped portion 124 of the pin 100. That is, the axial length L3 of the stepped portion 124 of the pin 100 is greater than or equal to the axial length L7 of each hole H1.

[0044] Figure 5 This diagram schematically illustrates the state in which the pin 100 is inserted into the hole H1 of plate 200. (Refer to...) Figure 5Since the lengths of each part of the pin 100 are related to the lengths of each part of the plate 200 as described above, the lower surface of the stepped portion 124 of the pin 100 contacts the bone or similar material, and the lower surface of the head body portion 122 of the pin 100 hardly presses against the upper surface of the inner flange portion 202 of the plate 200. Therefore, using this pin 100, when the pin 100 is subjected to ultrasonic vibration, the ultrasonic vibration hardly propagates to the plate 200, thus suppressing the deterioration of the plate 200 caused by ultrasonic vibration.

[0045] Refer to Figure 1 and Figure 2 The head 120 has a recess C1 that extends in the direction of the shaft portion 110. The recess C1 forms a generally cylindrical space. Details will be explained later, at the tip 530 of the handheld member 500 included in the ultrasonic welding apparatus 10 (see...). Figure 8 When inserted into the recess C1, the pin 100 is held by the handpiece 500 due to friction. Alternatively, the pin 100 can be manufactured, for example, by machining or injection molding.

[0046] As described above, the pin 100 and the plate 200 are both made of bio-absorbent materials. Examples of bioabsorbable materials include synthetic polymers such as polylactic acid-polyglycolic acid copolymer (PLAGA), poly-L-lactide (PLLA), polylactic acid (PLA), polyglycolic acid (PGA), polyglycolic acid, polylactide, poly-ε-caprolactone, lactide-glycolic acid copolymer, glycolide-ε-caprolactone copolymer, lactide-ε-caprolactone copolymer, polycitric acid, polymalic acid, poly-α-cyanoacrylate, poly-β-hydroxy acid, polytrimethylene oxalate, polytetramethylene oxalate, polyorthoester, polyorthocarbonate, polyethylene carbonate, poly-γ-benzyl-L-glutamate, poly-γ-methyl-L-glutamate, and poly-L-alanine; polysaccharides such as starch, alginic acid, hyaluronic acid, chitin, oxidized cellulose, chitosan, pectinic acid and their derivatives; and natural polymers such as gelatin, collagen, albumin, fibroin, and silk fibroin.

[0047] <1-2. Drill Bit Composition> Figure 6 This is a schematic diagram illustrating the configuration of drill bit 300. Drill bit 300 is used, for example, to form holes in the bones of animals such as humans. For example, pin 100 is fused into the hole formed by drill bit 300.

[0048] like Figure 6As shown, the drill bit 300 includes a drill bit body 310 and a drill bit tip 320. The drill bit body 310 includes a motor 312 and a power supply unit 314. The motor 312 is configured to drive the drill bit tip 320 to rotate. The power supply unit 314 is configured to supply power to the various components of the drill bit body 310 (e.g., the motor 312). The power supply unit 314 is, for example, a secondary battery such as a lithium-ion battery.

[0049] The drill tip 320 is configured to be inserted into an animal skeleton in a rotationally driven state, forming a hole in the animal skeleton. The drill tip 320 is detachable from the drill body 310. The drill tip 320 is mounted on the front end portion of the drill body 310. The drill tip 320 includes a connecting portion 322, a rod-shaped portion 324, and a front end portion 326. The connecting portion 322 is configured to be detachable from the drill body 310. The rod-shaped portion 324 extends from the connecting portion 322 in the direction of rotation of the drill tip 320.

[0050] The front end portion 326 is formed at the front end of the rod-shaped portion 324. In the front end portion 326, radially protruding convex portions and radially recessed concave portions are alternately formed in the direction of the rotation axis of the drill tip 320. The front end portion 326 has a tapered shape in which the diameter of the drill tip 320 decreases towards the front end. The angle formed between the rotation axis of the drill tip 320 and the outer peripheral surface of the front end portion 326 is θ2. θ2 is greater than 0° and is substantially equivalent to the angle θ1 formed between the central axis of the shaft portion 110 of the pin 100 and the outer peripheral surface of the shaft portion 110 (refer to...). Figure 2 That is, θ2 is preferably 3° to 20°, more preferably 5° to 10°.

[0051] Figure 7 This diagram schematically illustrates the insertion of a pin 100 into a hole H2 formed in the bone 400 using drill bit 300. (Refer to...) Figure 7 The inner surface of the hole H2 forms a cone shape. The slope of the cone formed by the inner surface of the hole H2 is substantially equal to the slope of the cone formed by the outer peripheral surface of the shaft portion 110 of the pin 100. The volume of the shaft portion 110 of the pin 100 is 110% to 130% of the volume of the hole H2 formed by the drill bit 300, preferably 115% to 128%, and more preferably 120% to 125%. Because the volume of the shaft portion 110 of the pin 100 is 110% or more of the volume of the hole H2, bio-absorbent material can be sufficiently filled into the hole H2, thus ensuring a firm weld on the pin 100.

[0052] Thus, since the volume of the shaft portion 110 of the pin 100 is larger than the volume of the hole H2, the pin 100 receives the ultrasonic welding device 10 (see reference). Figure 8Before the ultrasonic vibration, only a portion of the shaft portion 110 of the pin 100 can be inserted into the hole H2. Before the pin 100 receives ultrasonic vibration, the length L10 of the portion of the shaft portion 110 inserted into the hole H2 is at least 20%, preferably at least 35%, and more preferably at least 50% of the total length L9 of the shaft portion 110. Using the pin 100, even before the pin 100 receives ultrasonic vibration from the ultrasonic welding device 10, a portion of the shaft portion 110 can be inserted into the hole H2 of the bone 400. Then, the hole H2 acts as a guide, and with the pin 100 in a stable position, ultrasonic vibration propagates towards the pin 100, thus avoiding adverse conditions such as applying oblique forces to the pin 100.

[0053] <1-3. Composition of Ultrasonic Welding Device> Figure 8 This is a schematic diagram illustrating the configuration of the ultrasonic welding device 10. (Refer to...) Figure 8 The ultrasonic welding device 10 is used, for example, for welding the pin 100 of this embodiment. The ultrasonic welding device 10 has an oscillator 20 and a handheld device 500. The oscillator 20 and the handheld device 500 are connected by a cable 30.

[0054] The oscillator 20 is configured to convert power supplied from a commercial power source into ultrasonic power, which is then supplied to the handheld device 500 via cable 30. For example, the frequency of the ultrasonic power supplied by the oscillator 20 is substantially constant. Furthermore, the magnitude (product of voltage and current) of the ultrasonic power supplied by the oscillator 20 is substantially constant.

[0055] The handheld device 500 includes a BL transducer (Bolt-clamped Langevin type transducer) 510, a housing 520, an amplitude transformer 525, and a tip 530. The BL transducer 510 is configured to generate ultrasonic vibrations based on ultrasonic power supplied by the oscillator 20. The housing 520, for example, has a hollow cylindrical shape and is configured to house the BL transducer 510 inside. The amplitude transformer 525 is mounted on the front end of the BL transducer 510 and is configured to amplify the ultrasonic vibrations generated by the BL transducer 510.

[0056] The tip 530 is connected to the front end of the amplitude transformer 525, configured to propagate the ultrasonic vibration amplified by the amplitude transformer 525 to the object to be welded. The tip 530 can be detachable from the amplitude transformer 525, or it can be integrated with the amplitude transformer 525. The tip 530 is made of, for example, titanium or ceramic.

[0057] Figure 9 This is a schematic three-dimensional representation of the tip 530. (For example...) Figure 9As shown, the tip 530 has a base 535 and a protrusion 531. The base 535 has a generally cylindrical shape, for example. The protrusion 531 is formed on the front end face FC1 of the base 535 and has a generally cylindrical shape. The length (diameter) of the protrusion 531 in the width direction is smaller than the length (diameter) of the base 535 in the width direction. The protrusion 531 is configured to hold the pin 100, which is the object to be welded. Specifically, the protrusion 531 is inserted into the recess C1 of the pin 100 (see reference). Figure 1 and Figure 2 To keep the pin 100.

[0058] [2. Welding pins using an ultrasonic welding device] Figure 10 This diagram schematically illustrates the installation of the pin 100 on the protrusion 531 at the tip 530. (Refer to...) Figure 10 The pin 100 is installed onto the protrusion 531, for example, when the pin 100 is positioned on the mounting base 600. The mounting base 600 has a plurality of holes H3, each of which houses the pin 100.

[0059] First, the protrusion 531 of the tip 530 is inserted into the recess C1 of the head 120. With the protrusion 531 inserted into the recess C1, the pin 100 is held in place by the tip 530 due to friction. When the handpiece 500 is lifted while the pin 100 is held in place by the tip 530, the pin 100 is removed from the mounting base 600. This process is used to install the pin 100 onto the protrusion 531 of the tip 530.

[0060] Figure 11 This diagram illustrates how the welding of pin 100 is performed. (Refer to...) Figure 11 The horizontal axis represents time. In this example, the pins 100 are welded together with pins 100 inserted into both the hole formed in the plate 200 and the hole formed in the skeleton 400. By being welded together with pins 100, the plate 200 is fixed to the skeleton 400.

[0061] At time t0, pin 100 is pressed downward by tip 530, and pin 100 is slowly pressed into the cavity of bone 400. In this state, ultrasonic vibrations propagate from tip 530 to pin 100. Pin 100 is subjected to ultrasonic vibrations, thereby generating frictional heat between bone 400 and pin 100, and the side of pin 100 begins to melt. At time t1, pin 100 is further pressed into the cavity of bone 400, and the melting of pin 100 proceeds further. At time t2, the melting of shaft portion 110 proceeds further, and resin enters the gap of the cavity in bone 400. Thus, pin 100 and bone 400 are firmly bonded. In this way, plate 200 is fixed to bone 400 through the welding of pin 100. In addition, at time t2, shaft portion 110 may be completely melted or incompletely melted.

[0062] [3. Inhibition of accumulation and neck breakage] Figure 12 This diagram illustrates why the pins on the 100X object being compared tend to accumulate. (Refer to...) Figure 12 The pin 100X includes a shaft portion 110X and a head 120X. The shaft portion 110X has a tapered tip, but no tapering occurs elsewhere. Furthermore, the inner circumferential surface of the hole H4 formed on the bone 400 is also not tapered. When ultrasonic vibrations propagate to the pin 100X in this state, the contact area between the shaft portion 110X and the inner circumferential surface of the hole H4 is small, thus the ultrasonic waves concentrate near the recess C1X, generating significant frictional heat. Consequently, the frictional heat concentrates at the neck of the pin 100X, resulting in pin 100X buildup.

[0063] Figure 13 This diagram illustrates why the pin 100X, used in the comparison object, is prone to neck breakage. (Refer to...) Figure 13 As described above, when ultrasonic vibrations propagate to pin 100X, the contact area between the shaft portion 110X and the inner circumferential surface of the hole H4 is small. Therefore, the ultrasonic waves are concentrated near the recess C1X, generating significant frictional heat. Under these conditions, if a force is applied obliquely to press pin 100X, pin 100X will break off.

[0064] Figure 14 This diagram illustrates why the pin 100 in this embodiment is less prone to accumulation and neck breakage. (Refer to...) Figure 14In the shaft portion 110 of the pin 100, a tapered shape is formed, with the diameter of the shaft portion 110 decreasing from the upper end to the lower end. When a portion of the shaft portion 110 of the pin 100 is inserted into a hole H2 having the same tapered shape as the pin 100, the outer peripheral surface of the portion of the shaft portion 110 contacts the inner peripheral surface of the hole H2. In this state, when the pin 100 is subjected to ultrasonic vibration, because the contact area between the outer peripheral surface of the portion of the shaft portion 110 and the inner peripheral surface of the hole H2 is large, the ultrasonic waves tend to concentrate at the portion of the portion of the shaft portion 110 that contacts the hole H2. Therefore, by using the pin 100, when the pin 100 is subjected to ultrasonic vibration, frictional heat is concentrated at the portion of the portion of the shaft portion 110 that contacts the hole H2, and frictional heat does not concentrate at the neck of the pin 100, thus suppressing accumulation and neck breakage.

[0065] [4. Characteristics] As described above, in this embodiment, the shaft portion 110 of the pin 100 is tapered, with its diameter decreasing from the upper end to the lower end. For example, when a portion of the shaft portion 110 of the pin 100 is inserted into a hole H2 having the same tapered shape as the pin 100, the outer peripheral surface of the portion of the shaft portion 110 contacts the inner peripheral surface of the hole H2. In this state, when the pin 100 is subjected to ultrasonic vibration, the ultrasonic waves tend to concentrate at the portion of the shaft portion 110 that contacts the hole H2. Therefore, with the pin 100, when the pin 100 is subjected to ultrasonic vibration, frictional heat is concentrated at the portion of the shaft portion 110 that contacts the hole H2, and frictional heat does not concentrate at the junction (neck) of the shaft portion 110 and the head 120, thus suppressing accumulation and neck breakage.

[0066] [5. Other implementation methods] The ideas behind the above embodiments are not limited to those described above. An example of another embodiment that can apply the ideas described above will be described below.

[0067] <5-1> In the above embodiment, the head 120 of the pin 100 is provided with a stepped portion 124. However, the head 120 does not necessarily have to be designed with a stepped portion 124. In this case, the shaft portion 110 can extend from the lower end of the head body portion 122.

[0068] <5-2> Furthermore, in the above embodiment, the stepped portion 124 of the pin 100 is cylindrical. However, the shape of the stepped portion 124 does not necessarily have to be cylindrical. For example, the shape of the stepped portion 124 may be such that the radial length of the stepped portion 124 at the upper end is greater than the radial length of the stepped portion 124 at the lower end. This is as long as the diameter of the stepped portion 124 at the end of the head body portion 122 is smaller than the diameter of the head body portion 122, and the diameter of the stepped portion 124 at the end of the shaft portion 110 is greater than the diameter of the shaft portion 110 at the end of the stepped portion 124.

[0069] <5-3> The kit can be composed of the pin 100 and the drill bit 300 as described in the above embodiment. With this kit, when the pin 100 is welded into the hole H2 formed by the drill bit 300, the frictional heat is concentrated on the part of the shaft portion 110 of the pin 100 that contacts the hole H2, and the frictional heat is not concentrated on the neck of the pin 100, thus suppressing the accumulation and neck breakage.

[0070] The embodiments of the present invention have been described above as illustrative. That is, detailed description and drawings have been provided for illustrative purposes. Therefore, the constituent elements described in the detailed description and drawings sometimes include constituent elements that are not essential to solving the problem. Therefore, one should not immediately assume that these non-essential constituent elements are essential constituent elements simply because they are described in the detailed description and drawings.

[0071] Furthermore, the above embodiments are merely illustrative of the present invention in all respects. Various modifications and variations can be made to the above embodiments within the scope of the present invention. For example, at least a portion of the configuration in any one embodiment can be combined with at least a portion of the configuration in any other embodiment. That is, when implementing the present invention, specific configurations can be appropriately adopted according to the embodiments.

[0072] Explanation of reference numerals in the attached figures 10: Ultrasonic welding device; 20: Vibrator; 30: Cable; 100, 100X: Pins; 110, 110X: Shaft; 120, 120X: Head; 122: Head body; 124: Stepped part; 200: Plate; 202: Inner flange; 300: Drill bit; 310: Drill bit body; 312: Motor; 314: Power supply; 320: Drill bit tip; 322: Connecting part; 324: Rod-shaped part; 326: Front end; 400: skeleton; 500: handpiece; 510: BL vibrator; 520: outer shell; 525: amplitude rod; 530: tip; 531: protrusion; 535: base; 600: fixed platform; C1, C1X, C2: recess; F1: upper surface; F2: lower surface; FC1: front end face; H1: hole; H2, H3, H4: opening.

Claims

1. A pin that melts upon receiving ultrasonic vibrations from an ultrasonic welding device, characterized in that, The pin is made of a bio-absorbent material. The pin has a shaft portion including a first end and a second end in the axial direction, and a head formed at the first end. The diameter of the head is larger than the diameter of the shaft portion at the first end. The shaft portion is formed into a tapered shape, with the diameter decreasing from the first end to the second end.

2. The pin as described in claim 1, characterized in that, The head includes a main body and a stepped portion. The stepped portion is formed between the head body portion and the first end portion. The diameter of the stepped portion at the side end of the head body is smaller than the diameter of the head body. The diameter of the stepped portion at the first end side is greater than the diameter of the shaft portion at the first end.

3. The pin as described in claim 2, characterized in that, The pin is formed by passing through a hole formed in the plate. The diameter of the hole is larger than the diameter of the stepped portion at the side end of the head body portion but smaller than the diameter of the head body portion. The length of the stepped portion in the axial direction is greater than or equal to the length of the hole in the axial direction.

4. The pin as described in any one of claims 1 to 3, characterized in that, The pins are configured to be inserted into holes formed in animal bones. The hole is formed by inserting the drill tip, which is located on the drill bit, into the bone. The drill bit tip is formed into a tapered shape with its diameter decreasing towards the front end. Before receiving the ultrasonic vibration from the ultrasonic welding device, only a portion of the shaft portion of the pin can be inserted into the hole. The axial length of a portion of the shaft is more than 20% of the axial length of the entire shaft.

5. The pin as described in claim 4, characterized in that, The volume of the shaft is more than 110% of the volume of the hole.

6. A drill bit configured to form a hole for inserting a pin as described in any one of claims 1 to 3, characterized in that, A drill bit body having a drill tip and an electric motor that drives the drill tip to rotate. The drill bit tip is formed into a tapered shape with the diameter decreasing towards the front end.

7. A kit, characterized in that, It has a pin as described in any one of claims 1 to 3, and a drill bit as described in claim 6.

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