Artificial joint

Abstract

The present invention provides an artificial joint that reduces the burden of attachment work to the bones constituting the joint, and improves the durability or reliability of the joint after attachment. [Solution] The artificial joint 100 for the middle phalanx comprises a stem 101 formed in the shape of a rod and inserted into at least one of a pair of bones with one of its ends exposed, and a tip sliding body 120 provided at the exposed end of the stem 101 that slides directly or indirectly against the other bone in the pair of bones to change the relative angle between the two bones in the pair. The stem 101 has a concave stem-side fitting portion 110 at the exposed end. The tip sliding body 120 has a convex sliding body-side fitting portion 130 that fits into the stem-side fitting portion 110.

Description

Technical Field

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[0001] The present invention relates to an artificial joint attached between a pair of first bone and second bone constituting a joint of a human or an animal.

Background Art

[0002] Conventionally, there is an artificial joint attached between a pair of first bone and second bone constituting a joint of a human or an animal. For example, Patent Document 1 below discloses an artificial joint that is attached to a metacarpal bone and a proximal phalanx, which are a pair of first bone and second bone constituting a human middle finger interphalangeal joint (MP joint).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] However, in the artificial joint described in Patent Document 1 above, since three components, namely a metacarpal bone stem (or proximal phalanx stem), a set screw, and a head (socket), are assembled to the metacarpal bone (or proximal phalanx) of the pair of bones constituting the joint, there is a problem that the attachment work burden on the metacarpal bone (or proximal phalanx) is not small, and there are also concerns about the durability or reliability as a joint after attachment.

[0005] The present invention has been made to address the above problems, and an object thereof is to provide an artificial joint that can reduce the attachment work burden on the bones constituting the joint and improve the durability or reliability as a joint after attachment.

Summary of the Invention

[0006] To achieve the above objective, the present invention features an artificial joint to be attached between a pair of bones constituting a joint, comprising: a stem formed in the shape of a rod and inserted into at least one of the pair of bones with one of its ends exposed; and a tip sliding body provided at the exposed end of the stem, which slides directly or indirectly against the other bone of the pair of bones to change the relative angle between the two bones of the pair, wherein the stem has a stem-side fitting portion formed in a concave or convex shape at the exposed end, and the tip sliding body has a sliding body-side fitting portion formed in a convex or concave shape that fits into the stem-side fitting portion.

[0007] According to this, in an artificial joint, a stem inserted into at least one of the pair of bones constituting the joint and an end sliding body that slides directly or indirectly against the other bone to form the joint are directly connected to each other by a stem-side fitting portion or a sliding body-side fitting portion, respectively. This reduces the burden of attachment work to the bones constituting the joint and improves the durability or reliability of the joint after attachment.

[0008] Another feature of the present invention is that, in the artificial joint, the stem-side fitting portion and the sliding body-side fitting portion have a polygonal or gear-like cross-sectional shape.

[0009] According to this, because the cross-sectional shapes of the stem-side fitting portion and the sliding body-side fitting portion of the artificial joint are formed into polygonal or gear-like or other non-circular shapes, relative rotational displacement (orientation deviation) around the axial direction of the stem between the stem and the tip sliding body can be prevented, and the orientation of the attachment of the tip sliding body to the stem around this axial direction can be changed in stages. The gear-like shape of the cross-sectional shape of the stem-side fitting portion and the sliding body-side fitting portion includes shapes formed by extending radially from each center, such as a cross shape. Furthermore, polygonal shapes include, for example, triangles, squares, pentagons, or hexagons, but by forming a polygon with octagons or more, the orientation of the tip sliding body can be precisely defined.

[0010] Another feature of the present invention is that, in the artificial joint, the stem-side fitting portion and the sliding body-side fitting portion are formed in a tapered shape, resulting in a stronger fit as the fitting depth increases.

[0011] According to this, the artificial joint is formed with a tapered shape in which the stem-side fitting portion and the sliding body-side fitting portion become tighter as the fitting depth increases. Therefore, the two can be strongly connected simply by deeply fitting the stem-side fitting portion and the sliding body-side fitting portion together. In this case, both the stem-side fitting portion and the sliding body-side fitting portion may be formed with a tapered shape, or only one of them may be formed with a tapered shape. Here, the tapered shape is a narrowing shape if the stem-side fitting portion or the sliding body-side fitting portion is axial, and if it is a hole, it is a shape in which the shape of the inner part continuously narrows, and includes a sloped shape or a wedge shape.

[0012] Another feature of the present invention is that, in the artificial joint, one of the stem-side fitting portion and the sliding body-side fitting portion has a rod-shaped or cylindrical convex first portion and a groove-shaped or slit-shaped concave second portion extending in the fitting direction along the convex first portion, and the other of the stem-side fitting portion and the sliding body-side fitting portion has a cylindrical concave first portion that fits on the outside of the convex first portion and a convex second portion that extends convexly along the fitting direction along the concave first portion and fits into the concave first portion.

[0013] According to this, the artificial joint can firmly connect the stem and the tip sliding body through the fitting of the convex first part and the concave first part, and the fitting of the concave second part and the convex second part. In this case, the fitting of the concave second part and the convex second part can prevent relative rotational displacement (orientation deviation) around the axial direction of the stem between the stem and the tip sliding body.

[0014] Another feature of the present invention is that, in the artificial joint, the concave second portion and the convex second portion are formed in a tapered shape, which results in a stronger fit as the fitting depth increases.

[0015] According to this, the artificial joint is formed with a tapered shape in which the concave second part and the convex second part become tighter as the fitting depth increases. Therefore, the stem-side fitting part and the sliding body-side fitting part can be strongly connected simply by deeply fitting them together. In this case, both the concave second part and the convex second part may be formed with a tapered shape, or only one of them may be formed with a tapered shape. Furthermore, if the concave second part of the artificial joint is formed in a slit shape, the concave second part expands when the convex second part is inserted into the concave second part, which in turn expands the convex first part, thus making the fitting between the convex first part and the concave first part stronger.

[0016] Another feature of the present invention is that, in the artificial joint, the stem is a cylindrical body, tapered in shape with an outer diameter that continuously decreases in the direction of insertion into one of the bones, and has male threads formed on the outer surface of the cylindrical body.

[0017] According to this, the artificial joint has a cylindrical stem that is tapered, with its outer diameter continuously decreasing in the direction of insertion into one of the pair of bones constituting the joint, and has male threads formed on the outer surface of the cylinder. Therefore, it can be firmly connected to the bone by screwing it in over the entire axial range. In this case, the male threads should be tapping screws that screw in while forming female threads on the inner surface of the hole. [Brief explanation of the drawing]

[0018] [Figure 1] This is a partial side view showing the internal structure of the proximal interphalangeal joint portion of the left index finger, to which the middle phalanx artificial joint and the distal phalanx artificial joint according to the first embodiment of the present invention are attached. [Figure 2] Figure 1 is an exploded side view showing a schematic representation of the external structure of the middle phalanx artificial joint. [Figure 3] Figure 1 is a perspective view showing the external structure of the stem constituting a middle phalanx or distal phalanx artificial joint. [Figure 4] Figure 1 is a perspective view showing the external configuration of the tip sliding element that constitutes the artificial joint for the middle phalanx. [Figure 5] Figure 1 is an exploded side view showing a schematic representation of the external structure of the distal phalanx prosthesis. [Figure 6] This is a cross-sectional view of a middle phalanx, showing the external structure of a guide device inserted into the middle phalanx and the state in which the guide device is inserted into the middle phalanx. [Figure 7] These are front views showing the external and internal configurations of a drill tool used to drill pilot holes in the middle phalanges. [Figure 8] Figure 7 is a partially enlarged perspective view showing the external configuration of the drill part of the drilling tool. [Figure 9] These are front views showing the external and internal configurations of a milling tool used to shape a pilot hole formed within the middle phalanx bone. [Figure 10] Figure 9 is a partially enlarged perspective view showing the external configuration of the milling section of the milling tool. [Figure 11] It is a front view showing the external and internal configurations of an implant tool used when screwing a stem into a lower hole formed in the middle phalanx bone, respectively. [Figure 12] It is a partially enlarged perspective view showing the external configuration of the implant part in the implant tool shown in Fig. 11. [Figure 13] It is a front view showing the external and internal configurations of a facing tool used when facing the sliding body installation surface of the middle phalanx bone together with the stem arranged in the middle phalanx bone, respectively. [Figure 14] It is a bottom view showing the external configuration of the facing part in the facing tool shown in Fig. 13. [Figure 15] It is a cross-sectional view showing the internal configuration of an operation handle connected to each of a drill tool, a milling tool, an implant tool, and a facing tool shown in Figs. 7 to 14 for manual operation. [Figure 16] It is a cross-sectional view showing a state in which an end portion of the bone head of the middle phalanx bone for installing an artificial joint for the middle phalanx bone is resected to form a sliding body installation surface. [Figure 17] It is a cross-sectional view showing a state in which a lower hole is processed using a drill tool with respect to the middle phalanx bone shown in Fig. 6. [Figure 18] It is a cross-sectional view showing a state in which a lower hole is formed using a milling tool with respect to the middle phalanx bone shown in Fig. 17. [Figure 19] It is a cross-sectional view showing a state in which a stem is screwed in using an implant tool with respect to the middle phalanx bone shown in Fig. 18. [[ID=,27]]<00,00106>It is a cross-sectional view showing a state in which the sliding body installation surface is flattened using a facing tool with respect to the middle phalanx bone shown in Fig. 19. [Figure 21] It is a cross-sectional view showing a state in which a part of the side portion of the middle phalanx bone shown in Fig, 20 is resected to form a sliding body installation surface. [Figure 22] It is a cross-sectional view showing a state in which a tip sliding body is attached to a stem installed in the middle phalanx bone shown in Fig. 21. [Figure 23] It is a front view showing the external configuration of a removal tool used when removing a stem attached in the middle phalanx bone. [Figure 24]This is a cross-sectional view showing the state of removing a stem by connecting an extraction tool to the stem that has been attached inside the middle phalanx. [Figure 25] This is an exploded side view showing a schematic representation of the external structure of an artificial joint for a middle phalanx according to a second embodiment of the present invention. [Figure 26] Figure 25 is a perspective view showing the external structure of the stem that constitutes the middle phalanx artificial joint. [Figure 27] Figure 25 is a perspective view showing the external configuration of the tip sliding element that constitutes the artificial joint for the middle phalanx. [Figure 28] Figure 26 is a partially enlarged perspective view showing the external appearance of the milling section of a milling tool used to shape the pilot hole formed in the middle phalanx bone where the stem shown is installed. [Figure 29] Figure 26 is a partially enlarged perspective view showing the external appearance of the implant portion of an implant device for screwing the stem into a pilot hole formed in the middle phalanx bone. [Figure 30] Figure 28 is a cross-sectional view showing the process of surface finishing being performed on the sliding surface of the middle phalanx bone, where the stem is installed, using the milling tool shown. [Figure 31] This is a cross-sectional view showing the state in which the tip sliding body shown in Figure 27 is attached to the stem shown in Figure 26, which is installed inside the middle phalanx. [Figure 32] This is a perspective view showing the external configuration of a stem according to a modified example of the present invention. [Figure 33] This is a perspective view showing the external configuration of the stem and tip sliding body according to another modification of the present invention. [Modes for carrying out the invention]

[0019] <First Embodiment> Hereinafter, a first embodiment of the artificial joint according to the present invention will be described with reference to the drawings. Figure 1 is a side view showing the inside of the distal interphalangeal joint (hereinafter also referred to as the "DIP joint") of the left index finger, to which the middle phalanx artificial joint 100 and the distal phalanx artificial joint 200 according to the first embodiment of the present invention are attached, respectively. Figure 2 is an exploded side view showing a schematic of the external structure of the middle phalanx artificial joint 100 shown in Figure 1. Figure 3 is a perspective view showing the external structure of the stems 101 and 201 that constitute the middle phalanx artificial joint 100 or the distal phalanx artificial joint 200 shown in Figure 1. Figure 4 is a perspective view showing the external structure of the tip sliding body 120 that constitutes the middle phalanx artificial joint 100 shown in Figure 1. Figure 5 is an exploded side view showing a schematic of the external structure of the distal phalanx artificial joint 200 shown in Figure 1. Note that the figures referenced in this specification are schematic representations, such as exaggerating some components, in order to facilitate understanding of the present invention. Therefore, the dimensions and proportions of each component may differ.

[0020] (Composition of 100 artificial joints for the middle phalanx) This artificial joint 100 for the middle phalanx is an artificial joint that is attached to the middle phalanx I, which is one of the joints of the fingers of the human hand and constitutes the distal interphalangeal joint (DIP joint). The artificial joint 100 for the middle phalanx mainly consists of a stem 101 and an end sliding body 120.

[0021] The stem 101 is a component that is attached to the middle phalanx I of a human finger and holds the tip sliding body 120, and is constructed by forming a rod shape from a metal or resin material. This stem 101 mainly consists of a stem body 102 and a stem-side fitting portion 110.

[0022] The stem body 102 is the part that is inserted and attached into the middle phalanx I of the human hand, and is formed in the shape of a rod with a length and thickness that can be accommodated in the medullary cavity MC (also called the "medullary cavity") inside the middle phalanx I. In this embodiment, the stem body 102 is formed in the shape of a cylinder with through holes 103 that open at both ends in the longitudinal direction. The stem body 102 is also formed in a tapered shape, with the outer diameter continuously decreasing from one end (upper side in the figure) to the other end (lower side in the figure). The stem body 102 has a female threaded portion 104, a male threaded portion 105, and a stem-side fitting portion 110 formed thereon.

[0023] The through-hole 103 is the portion through which the guide tool 300 (described later) passes and through which the female thread portion 104 is formed. It is a circular hole with a perfectly round cross-section that penetrates between the longitudinal ends of the stem body 102. This through-hole 103 consists of a fitting side hole portion 103a and a main body hole portion 103b.

[0024] The fitting portion side hole 103a is the portion into which the central part of the sliding body side fitting portion 130 of the tip sliding body 120 fits, and is formed in the portion where the stem side fitting portion 110 is formed, which is one end (upper side in the figure) of both ends of the stem body 102. One end (upper side in the figure) of this fitting portion side hole 103a opens to the aforementioned one end of the stem body 102, and the other end (lower side in the figure) communicates with the main body hole 103b. In this embodiment, the fitting portion side hole 103a is formed with a larger inner diameter than the main body hole 103b, more specifically, with a constant inner diameter larger than the inner diameter of the female thread portion 104.

[0025] The main body hole 103b penetrates from the fitting side hole 103a through to the other end (lower side in the figure) of the stem body 102 and opens at the other end. In this case, the main body hole 103b has an inner diameter that is approximately the same as the outer diameter of the guide tool 300, which will be described later, and is formed with a constant inner diameter along its entire length. A female thread portion 104 is formed in a part of this main body hole 103b.

[0026] In this case, the inner diameter of the main body hole 103b being approximately the same as the outer diameter of the guide tool 300 includes a range that is the same as the outer diameter of the guide tool 300 and is large enough for the guide tool 300 to pass through, or a range that is large enough so that when the guide tool 300 has passed through, there is no noticeable looseness when operated by hand relative to the guide tool 300, or the axis of the drill part 302 is approximately parallel (at an angle of 3° or less relative to the guide tool 300) and can be considered to be substantially the same inner diameter.

[0027] The female threaded portion 104 is a part for screw-fitting the removal tool 330 used when removing the stem body 102 installed inside the middle phalanx bone I, and extends from the portion communicating with the fitting side hole 103a in the main body hole 103b to the longitudinal center of the main body hole 103b. In this case, the female threaded portion 104 is configured with a reverse thread with respect to the male threaded portion 105, which will be described later.

[0028] The male threaded portion 105 is a part for fixing the stem body 102 inside the middle phalanx bone I by screwing it into the middle phalanx bone I, and is formed on the outer surface between both ends of the stem body 102. In this case, the male threaded portion 105 in this embodiment is a self-tapping screw that threads itself as it is inserted into the middle phalanx bone I, even if there is no internal thread formed inside it.

[0029] The stem-side fitting portion 110 is the part for attaching the tip sliding body 120 to the stem body 102, and is formed in a concave shape on the tip end (upper end in the figure) opposite to the tip end (lower end in the figure) that is inserted into the middle phalanx I of the stem body 102. Specifically, the stem-side fitting portion 110 consists of the fitting portion side hole 103a and four slits 111, and is formed as a cross-shaped notch when viewed from one end side (upper side in the figure) of the stem body 102.

[0030] The four slits 111 are the portions into which the projections 131 on the sliding body side fitting portion 130 fit. The annular portion on the outer side of the fitting portion side hole 103a at one end (upper side in the figure) of the stem body 102 is cut out axially from the upper end, with the annular portion penetrating the stem body 102 radially. In this case, each slit 111 is formed with a constant groove width. These four slits 111 are evenly arranged along the circumferential direction of the stem body 102.

[0031] In this embodiment, the stem 101 has an overall length of 10 mm, a maximum outer diameter of 3.2 mm, a taper angle of 3°, an M1 × 0.25 female thread portion 104 (minimum inner diameter of the female thread portion 104 and inner diameter of the main body hole portion 103b of 0.73 mm), an inner diameter of 1.1 mm for the fitting portion side hole portion 103a, a groove width of 0.6 mm for the stem side fitting portion 110, and a groove depth of 2.2 mm for the stem side fitting portion 110. This stem 101 can be manufactured using known machining processes such as cutting or forging, or known injection molding processes.

[0032] The tip sliding body 120 is a component that slides against the tip sliding body 220 of the distal phalanx artificial joint 200 attached to the distal phalanx D, thereby changing the relative angle between the middle phalanx I and the distal phalanx D, and is made of metal or resin material. This tip sliding body 120 mainly consists of a sliding body body 121 and a sliding body side fitting portion 130.

[0033] The sliding body 121 is the portion of the tip sliding body 220 of the distal phalanx artificial joint 200 that slides against the sliding body 221, and is composed of a convexly curved surface portion 121a and a base portion 121b formed in a flat surface shape on the back side of the curved surface portion 121a. In other words, the sliding body 121 is a component corresponding to the femoral head in the bone that constitutes the joint.

[0034] The sliding body side fitting portion 130 is the part that attaches the tip sliding body 120 to the stem body 102 by fitting into the stem side fitting portion 110 of the stem body 102, and is formed by protruding convexly from the base portion 121b of the sliding body body 121. Specifically, the sliding body side fitting portion 130 is composed of four protruding pieces 131 and is formed in a cross shape when viewed from the bottom of the sliding body body 121.

[0035] The four protruding pieces 131 are portions that fit into the four slits 111 in the stem-side fitting portion 110, and each of the four plate-like bodies extending vertically from the base portion 121b is formed to protrude in directions parallel to the base portion 121b. In other words, the sliding body-side fitting portion 130 is formed in a cross shape corresponding to the four slits 111 arranged in a cross shape.

[0036] In this case, the outer edge of the sliding body side fitting portion 130 is formed to a size that does not protrude beyond the outer edge (outer diameter) of the male thread portion 105 of the stem 101. Furthermore, the sliding body side fitting portion 130 is formed in a wedge shape with four projections 131 that protrude in a cross shape in all four directions, and the thickness of the plate gradually increases from the tip to the base. In this embodiment, the thickness of each of the four projections 131 in the sliding body side fitting portion 130 is formed to increase continuously from a thickness less than the groove width of the stem side fitting portion 110 to a thickness greater than the groove width. This tip sliding body 120 can be manufactured using known machining processes such as cutting or forging, or known injection molding processes.

[0037] (Composition of the 200-unit artificial joint for distal phalanx) This distal phalanx artificial joint 200 is an artificial joint that is attached to the distal phalanx D, which together with the middle phalanx I to which the middle phalanx artificial joint 100 is attached, constitutes the DIP joint. As shown in Figure 5, this distal phalanx artificial joint 200 is mainly composed of a stem 201 and a tip sliding body 220, similar to the middle phalanx artificial joint 100.

[0038] The stem 201 is a component that is attached to the distal phalanx D of a human finger to hold the tip sliding body 220, and is constructed by forming a metal or resin material into a rod shape. This stem 201 is constructed in the same way as the stem 101. That is, the stem 201 is constructed with a stem body 202, a through hole 203 (fitting part side hole 103a, main body hole 103b), a female threaded part 104, a male threaded part 105, a stem-side fitting part 110, and a slit 111, respectively, which are configured in the same way as the stem 101. For this reason, a detailed description of the stem 201 is omitted, but it is naturally formed to a size that can be inserted into the distal phalanx D.

[0039] The tip sliding body 220 is a component that slides against the tip sliding body 120 in the middle phalanx artificial joint 100 attached to the middle phalanx I, thereby changing the relative angle between the middle phalanx I and the distal phalanx D, and is made of metal or resin. This tip sliding body 220 mainly consists of a sliding body body 221 and a sliding body side fitting portion 230.

[0040] The sliding body 221 is the portion of the tip sliding body 120 in the middle phalanx artificial joint 100 that slides against the sliding body 121, and is composed of a concave curved surface portion 221a and a base portion 221b formed on the back side of the curved surface portion 221a in a flat surface shape. In other words, the sliding body 221 is a component that corresponds to the concave acetabulum that receives the femoral head in the bone constituting the joint.

[0041] The sliding body side fitting portion 230 is a part for attaching the tip sliding body 220 to the stem body 202 by fitting into the stem side fitting portion 210 of the stem body 202, and is formed by protruding convexly from the base portion 221b of the sliding body body 221. This sliding body side fitting portion 230 is configured in the same way as the sliding body side fitting portion 230. That is, the sliding body side fitting portion 230 is configured with a projection piece 231 similarly configured to the projection piece 131 of the sliding body side fitting portion 130. For this reason, a detailed explanation of the sliding body side fitting portion 230 is omitted.

[0042] (Description of guide tool 300, drill tool 301, milling tool 305, implant tool 310, surface preparation tool 315, and operating handle 320) Next, we will describe the guide tool 300, drill tool 301, milling tool 305, implant tool 310, surfacer tool 315, and operating handle 320 used for attaching the middle phalanx artificial joint 100 and distal phalanx artificial joint 200 configured in this way to the middle phalanx I or distal phalanx D. Note that each of the guide tool 300, drill tool 301, milling tool 305, implant tool 310, surfacer tool 315, and operating handle 320 may be configured to be used in common for the middle phalanx artificial joint 100 and the distal phalanx artificial joint 200, or they may be configured to be incompatible for each of the two. However, since the tools used for the middle phalanx artificial joint 100 and the tools used for the distal phalanx artificial joint 200 are configured similarly to each other, we will only describe the tools used for the middle phalanx artificial joint 100.

[0043] As shown in Figure 6, the guide device 300 is an instrument inserted into the middle phalanx I to guide the drill tool 301, milling tool 305, implant tool 310, surface preparation tool 315, and stem 101 in the axial direction of the middle phalanx I, and is constructed by forming a metal or resin material into a linear shape. Specifically, the guide device 300 is formed to have a diameter that allows the through-hole 103 formed in the stem 101 of the middle phalanx artificial joint 100 to pass through, and to be exposed from the middle phalanx I when inserted into the middle phalanx I.

[0044] In this case, the diameter of the guide tool 300 should be such that the axis of the stem 101 remains approximately parallel to the guide tool 300 (at an angle of 3° or less relative to the guide tool 300) when inserted through the through hole 103. Specifically, the difference between the guide tool 300 and the inner diameter of the through hole 103 should be greater than 0 mm and less than or equal to 1 mm. Furthermore, the length of the guide tool 300 should be such that the length of the portion exposed from the middle phalanx I when inserted into the middle phalanx I is longer than the length of the stem 101, and more preferably longer than the length of the drill tool 301, milling tool 305, implant tool 310, and surface preparation tool 315.

[0045] Furthermore, the guide tool 300 may or may not be flexible, but it is constructed to have sufficient rigidity to stand on its own when erected in the axial direction. In this embodiment, the guide tool 300 is made of a flexible stainless steel wire with a diameter of 0.7 mm and a length of 200 mm. The tip of the guide tool 300 may be formed as a flat surface, or it may be formed as a needle-shaped point. The wire constituting this guide tool 300 can be manufactured by drawing.

[0046] The drill tool 301 is an instrument for forming a pilot hole H for positioning the stem 101 within the middle phalanx I, and is constructed by forming a metal or resin material into a rod shape. More specifically, as shown in Figures 7 and 8, the drill tool 301 mainly comprises a drill portion 302, a handle portion 303, and a guide hole 304, respectively.

[0047] The drill portion 302 is the part used for cutting the inside of the middle phalanx bone I, and is constructed by forming a helical cutting edge on the surface of a round bar body. This drill portion 302 is formed to have a smaller diameter than the outer diameter of the stem 101 and a longer length than the length of the stem 101.

[0048] The handle portion 303 is the part that supports the drill portion 302 and is formed as a straight rod. The drill portion 302 is provided at one end of the handle portion 303, protruding in the axial direction, and a handle mounting portion 303a is formed at the other end for detachably attaching the operating handle 320. In this embodiment, the handle mounting portion 303a is composed of a D-cut surface, which is formed by cutting out a part of the round rod-shaped handle portion 303 in a flat surface in the axial direction to create a D-shaped cross-section, and a groove portion that extends circumferentially in a concave shape in the circular portion of the cross-section. These drill portion 302 and handle portion 303 are integrally formed from a round rod-shaped stainless steel material.

[0049] The guide hole 304 is a portion for the guide tool 300 to pass through, and is composed of through holes opening at the tip of the drill portion 302 and the end of the handle portion 303, respectively. In this case, the inner diameter of the guide hole 304 is the same as the outer diameter of the guide tool 300 (same meaning as "approximately the same inner diameter" in the fitting portion side hole portion 103a) and is large enough for the guide tool 300 to pass through, or is large enough so that when the guide tool 300 is passed through, there is no rattle felt when operating the guide tool 300 by hand, or the axis of the drill portion 302 is kept approximately parallel (3° or less relative to the guide tool 300). Specifically, the difference from the diameter of the guide tool 300 should be 0 mm or more and 1 mm or less. In this embodiment, the inner diameter of the guide hole 304 is formed to be 0.7 mm.

[0050] The milling tool 305 is an instrument for more precisely shaping the pilot hole H formed in the middle phalanx bone I by the drilling tool 301, and is constructed by forming a metal or resin material into a rod shape. More specifically, as shown in Figures 9 and 10, the milling tool 305 mainly comprises a milling section 306, a handle section 307, and a guide hole 308, respectively.

[0051] The milling section 306 is a part for cutting the opening or side of the pilot hole H formed in the middle phalanx bone I, and is constructed by forming a linear or helical cutting edge on the surface of a round bar body. This milling section 306 is formed to have a smaller diameter than the outer diameter of the stem 101, but its length is appropriately set according to the range of milling of the pilot hole H. In this embodiment, the milling section 306 is formed to have a length of approximately 1 / 3 of the depth of the pilot hole H. In other words, this milling tool 305 corresponds to a reamer tool used for shaping holes.

[0052] The handle portion 307 is the part that supports the milling portion 306 and is formed as a straight rod. The milling portion 306 is provided at one end of the handle portion 307, protruding in the axial direction, and a handle mounting portion 307a is formed at the other end for detachably attaching the operating handle 320. In this embodiment, the handle mounting portion 307a is composed of a D-cut surface, which is formed by cutting out a part of the round rod-shaped handle portion 307 in a flat surface in the axial direction to create a D-shaped cross-section, and a groove portion that extends circumferentially in a concave shape in the circular portion of the cross-section. These milling portion 306 and handle portion 307 are integrally formed from a round rod-shaped stainless steel material.

[0053] The guide hole 308 is a portion for the guide tool 300 to pass through, and is composed of through holes opening at the tip of the milling portion 306 and the end of the handle portion 307, respectively. In this case, the inner diameter of the guide hole 308 is the same as the outer diameter of the guide tool 300 (same meaning as "approximately the same inner diameter" in the fitting portion side hole portion 103a) and is large enough for the guide tool 300 to pass through, or is large enough so that when the guide tool 300 is passed through, there is no rattle felt when operating the guide tool 300 by hand, or the axis of the milling portion 306 is approximately parallel to the guide tool 300 (at an angle of 3° or less with respect to the guide tool 300). Specifically, the difference between the diameter of the guide tool 300 and the guide hole 308 should be 0 mm or more and 1 mm or less. In this embodiment, the inner diameter of the guide hole 308 is formed to be 0.7 mm.

[0054] The implant device 310 is a tool for screwing the stem 101 into a pilot hole H formed in the middle phalanx bone I, and is constructed by forming a metal or resin material into a rod shape. More specifically, as shown in Figures 11 and 12, the implant device 310 mainly comprises an implant-side fitting portion 311, a handle portion 313, and a guide hole 314, respectively.

[0055] The implant-side fitting portion 311 is the part that fits onto the stem-side fitting portion 110 of the stem 101 and is used to screw the stem 101 into the pilot hole H formed in the middle phalanx bone I. It is formed by protruding convexly from the tip of the handle portion 313. Specifically, the implant-side fitting portion 311 is composed of four projections 312 and is formed in a cross shape when viewed from the bottom of the implant device 310.

[0056] The four projections 312 are parts that fit into the four slits 111 in the stem-side fitting portion 110, and each of the four plate-like bodies extending axially from the tip of the handle portion 313 is formed to protrude in four directions parallel to a plane perpendicular to the coaxial direction. In other words, the implant-side fitting portion 311 is formed in a cross shape corresponding to the four slits 111 arranged in a cross shape, similar to the sliding body-side fitting portion 130.

[0057] In this case, the outer edge of the implant-side mating portion 311 is formed to a size that does not protrude beyond the outer edge (outer diameter) of the male threaded portion 105 of the stem 101. Furthermore, the implant-side mating portion 311 has four projections 312 that extend in a cross shape in all four directions, and these projections are formed with a constant thickness from the tip to the base. In this embodiment, the thickness of each of the four projections 312 on the implant-side mating portion 311 is formed to be less than or equal to the groove width of the stem-side mating portion 110.

[0058] The handle portion 313 is the part that supports the implant-side fitting portion 311 and is formed as a straight rod. The implant-side fitting portion 311 is provided at one end of the handle portion 313, protruding in the axial direction, and a handle mounting portion 313a is formed at the other end for detachably attaching the operating handle 320. In this embodiment, the handle mounting portion 313a is composed of a D-cut surface, which is formed by cutting out a part of the round rod-shaped handle portion 313 in a flat surface in the axial direction to create a D-shaped cross-section, and a groove portion that extends circumferentially in a concave shape in the circular portion of the cross-section. These implant-side fitting portion 311 and handle portion 313 are integrally formed from a rod-shaped stainless steel material.

[0059] The guide hole 314 is a portion for the guide tool 300 to pass through, and is composed of through holes opening at the tip of the implant-side fitting portion 311 and the end of the handle portion 313, respectively. In this case, the inner diameter of the guide hole 314 is the same as the outer diameter of the guide tool 300 (same as "approximately the same inner diameter" in the fitting portion side hole portion 103a) and is large enough for the guide tool 300 to pass through, or is large enough so that when the guide tool 300 is passed through, there is no feeling of looseness when the guide tool 300 is operated by hand, or the axis of the implant-side fitting portion 311 is approximately parallel to the guide tool 300 (at an angle of 3° or less relative to the guide tool 300). Specifically, the difference between the diameter of the guide tool 300 and the guide hole 314 should be 0 mm or more and 1 mm or less. In this embodiment, the inner diameter of the guide hole 314 is formed to be 0.7 mm.

[0060] The surface leveling tool 315 is a device for making the sliding body mounting surface S, through which a pilot hole H formed in the middle phalanx bone I opens, flush with the end of the stem 101 inserted into the pilot hole H. It is constructed by forming a rod shape from a metal or resin material. More specifically, as shown in Figures 13 and 14, the surface leveling tool 315 mainly comprises a surface leveling portion 316, a handle portion 317, and a guide hole 318.

[0061] The surface-finishing portion 316 is a part used for machining both the sliding body mounting surface S, through which the pilot hole H formed in the middle phalanx bone I opens, and the end of the stem 101 inserted into the pilot hole H, in order to make them flush. It is constructed by forming countless file-like cutting edges on the surface of a disc. This surface-finishing portion 316 is formed to cover the end face of the middle phalanx bone I through which the pilot hole H opens.

[0062] The handle portion 317 is the part that supports the surface-finishing portion 316 and is formed as a straight rod. The surface-finishing portion 316 is provided at one end of the handle portion 317, protruding in the axial direction, and a handle mounting portion 317a is formed at the other end for detachably attaching the operating handle 320. In this embodiment, the handle mounting portion 317a is composed of a D-cut surface, which is formed by cutting out a part of the round rod-shaped handle portion 317 in a flat surface in the axial direction to create a D-shaped cross-section, and a groove portion that extends circumferentially in a concave shape in the circular portion of the cross-section. These surface-finishing portion 316 and handle portion 317 are integrally formed from a rod-shaped stainless steel material.

[0063] The guide hole 318 is a portion for the guide tool 300 to pass through, and is composed of through holes opening at the tip of the surface-finishing portion 316 and the end of the handle portion 317, respectively. In this case, the inner diameter of the guide hole 318 is the same as the outer diameter of the guide tool 300 (same meaning as "approximately the same inner diameter" in the fitting portion side hole portion 103a) and is large enough for the guide tool 300 to pass through, or is large enough so that when the guide tool 300 is passed through, there is no rattle felt when the guide tool 300 is operated by hand, or the axis of the surface-finishing portion 316 (axis of the handle portion 317) is approximately parallel to the guide tool 300 (at an angle of 3° or less with respect to the guide tool 300). Specifically, the difference between the diameter of the guide tool 300 and the inner diameter of the guide hole 318 should be 0 mm or more and 1 mm or less. In this embodiment, the inner diameter of the guide hole 318 is formed to be 0.7 mm.

[0064] The operating handle 320 is an instrument for rotating the drill tool 301, milling tool 305, implant tool 310, and surface preparation tool 315 relative to the middle phalanx bone I, and is constructed from a metal or resin material formed in a T-shape when viewed from the front. Specifically, as shown in Figure 15, the operating handle 320 mainly comprises a connecting portion 321, an operating portion 322, and a guide hole 323.

[0065] The connecting portion 321 is a part that is detachably connected to the handle mounting portions 303a, 307a, 313a, and 317a of the drill tool 301, milling tool 305, implant tool 310, and surface finishing tool 315, respectively, and is constructed with a round bar body equipped with a fitting portion 321a and a locking mechanism 321b.

[0066] The fitting portion 321a is a bottomed hole into which the handle mounting portions 303a, 307a, 313a, and 317a are fitted, and is formed extending axially with an opening at one end of the round bar body. In this embodiment, the hole constituting the connecting portion 321 has a D-shaped cross-section. As a result, the fitting portion 321a prevents the drill tool 301, milling tool 305, implant tool 310, and surface preparation tool 315 from rotating relative to the operating handle 320, and allows them to rotate integrally with the connecting portion 321.

[0067] The locking mechanism 321b is a part that prevents the handle mounting parts 303a, 307a, 313a, and 317a, which are fitted into the fitting part 321a, from easily coming loose. It consists of a ball exposed from the inner circumferential surface of the fitting part 321a and a cylindrical leaf spring fitted to the outer circumference of the connecting part 321 to elastically press the ball into the inside of the fitting part 321a. This locking mechanism 321b prevents the handle mounting parts 303a, 307a, 313a, and 317a from easily coming loose by elastically fitting the ball into the concave groove of the handle mounting parts 303a, 307a, 313a, and 317a that are fitted into the fitting part 321a, while allowing insertion and removal of the handle mounting parts 303a, 307a, 313a, and 317a.

[0068] The operating section 322 is the part that the operator (primarily a physician) grips to rotate the operating handle 320, and is composed of a rod-shaped body extending in a direction perpendicular to the connecting section 321 (horizontal direction as shown in the figure). This operating section 322 is formed at the end of the connecting section 321 opposite to the opening of the fitting section 321a. These connecting section 321 and operating section 322 are integrally formed from a rod-shaped stainless steel material.

[0069] The guide hole 323 is a portion through which the guide tool 300 passes, and is composed of a through hole that passes through the connecting portion 321 and the operating portion 322, respectively. In this embodiment, the guide hole 323 is composed of a through hole that extends parallel to the axial direction of the fitting portion 321a so as to open on the bottom (innermost part) of the fitting portion 321a and on the outer circumferential surface of the operating portion 322 facing the bottom. The guide hole 323 should be formed with an inner diameter through which the guide tool 300 can pass. It should be the same as the outer diameter of the guide tool 300 (same as "approximately the same inner diameter" in the fitting side hole 103a) and large enough for the guide tool 300 to pass through, or large enough so that when the guide tool 300 is passed through, there is no rattle felt when the guide tool 300 is operated by hand, or the axis of the connecting portion 321 is approximately parallel to the guide tool 300 (at an angle of 3° or less with respect to the guide tool 300). Specifically, the difference between the diameter of the guide tool 300 and the guide hole 323 should be 0 mm or more and 1 mm or less.

[0070] In this embodiment, the guide hole 318 is formed with an inner diameter of 1 mm. These drilling tools 301, milling tool 305, implanting tool 310, surface preparation tool 315, and operating handle 320 can be manufactured using known machining processes such as cutting or forging, or known injection molding processes. In the operating handle 320 shown in Figure 15, the handle mounting portion 303a of the drilling tool 301 is shown inserted into the connecting portion 321, and the same applies to the milling tool 305, implanting tool 310, and surface preparation tool 315.

[0071] (Implantation of artificial joint 100 for the middle phalanx and artificial joint 200 for the distal phalanx) Next, the procedure for attaching the artificial joint 100 for the middle phalanx and the artificial joint 200 for the distal phalanx, configured in this manner, to the middle phalanx I or the distal phalanx D will be described. In this case, since the procedure for attaching the artificial joint 100 for the middle phalanx I and the procedure for attaching the artificial joint 200 for the distal phalanx D are similar, the procedure for attaching the artificial joint 100 for the middle phalanx I will be described. A physician or other worker performing the procedure for attaching the artificial joint 100 for the middle phalanx I first prepares the guide tool 300, drill tool 301, milling tool 305, implant tool 310, surface preparation tool 315, and operating handle 320, respectively.

[0072] Next, the worker performs the first step, an osteotomy. As shown in Figure 16, this osteotomy involves cutting and removing a portion of the tip (corresponding to the femoral head) of the middle phalanx I that constitutes part of the DIP joint, forming a flat sliding surface S, and is performed on the exposed DIP joint. This osteotomy is performed by incising the finger of the patient using a dorsal or palmar approach to expose the DIP joint and then resecting the end of the middle phalanx I; however, this procedure itself is a known procedure. As a result of this procedure, a flat sliding surface S is formed on the middle phalanx I, and the inside of the middle phalanx I opens up to this sliding surface S, exposing the medullary cavity MC.

[0073] Next, the worker performs the second step, which is the installation of the guide device 300. As shown in Figure 6, this installation of the guide device 300 involves installing it at the central position where the stem 101 will be installed inside the middle phalanx bone I. Specifically, the worker inserts the guide device 300 into the interior of the middle phalanx bone I through the opening of the sliding body installation surface S. In this case, the worker inserts the guide device 300 along the central position where the stem 101 will be installed until the tip of the guide device 300 abuts against the inner wall surface on the other end (the lower end in the figure) of the middle phalanx bone I.

[0074] Furthermore, the worker can insert the guide tool 300 into the middle phalanx I while rotating it around its axis, or without rotating it. The worker should also insert the guide tool 300 until its tip penetrates the medullary cavity MC and slightly pierces the inner surface of the middle phalanx I. In this way, the guide tool 300 is installed in the middle phalanx I at the central position where the stem 101 is installed, extending linearly outward from the sliding body installation surface S (in reality, it is curved due to its own weight). Note that the guide tool 300 can be easily pierced into the inner surface of the middle phalanx I by shaping its tip into a pointed form.

[0075] Next, the worker performs the third step of forming the pilot hole H. Here, the pilot hole H is a bottomed hole formed in the middle phalanx bone I for setting the stem 101, and is formed along the axial direction (longitudinal direction) of the middle phalanx bone I. In this case, the inner diameter of the pilot hole H may be greater than or equal to the root diameter and less than or equal to the peak diameter of the male thread portion 105 of the stem 101, but it is preferable that it be formed to be the same diameter as the root diameter or smaller than the root diameter.

[0076] After preparing the drill tool 301, the operator inserts the tip of the handle portion 303 of the drill tool 301 (the upper end shown in the figure) into the connecting portion 321 of the operating handle 320 (see Figure 15). In this case, the operator can attach the drill tool 301 to the operating handle 320 with a single touch by elastically fitting the ball of the locking mechanism 321b inside the connecting portion 321 into the groove of the handle mounting portion 303a of the drill tool 301. In this case, the guide hole 304 of the drill tool 301 and the guide hole 323 inside the operating handle 320 are arranged coaxially.

[0077] Next, the operator operates the operating handle 320 to pass the guide tool 300, which extends from the sliding surface S of the middle phalanx bone I, through the guide holes 304 and 323 of the drill tool 301 and the operating handle 320, respectively. In this case, the operator passes the tip of the guide tool 300, which extends from the sliding surface S of the middle phalanx bone I, through the guide hole 304 that opens at the tip of the drill portion 302 of the drill tool 301. As a result, the tip of the drill portion 302 of the drill tool 301 faces the sliding surface S with the guide tool 300 extending from the middle phalanx bone I having passed through it.

[0078] Next, as shown in Figure 17, the operator rotates the operating handle 320 to rotate the entire drill tool 301 around its axis, inserting the tip of the drill portion 302 into the middle phalanx I, thereby forming a pilot hole H inside the middle phalanx I. In this case, the drill tool 301 forms the pilot hole H by removing a portion of the medullary cavity MC and a portion of the inner circumference of the middle phalanx I. Furthermore, in this case, since the guide tool 300 passes through the drill tool 301 and the operating handle 320, the guide tool 300 rotates around the guide tool 300 as the center of rotation, allowing the pilot hole H to be formed inside the middle phalanx I along the guide tool 300 (in other words, along the longitudinal direction of the middle phalanx I). In addition, in this case, the operator can guide the drill tool 301 more accurately by gripping the guide tool 300, which extends through the operating handle 320, and keeping it taut in a straight line.

[0079] The operator advances the drill section 302 to the depth required to install the stem 101, then retracts the drill section 302 and removes it from the pilot hole H. Next, the operator operates the operating handle 320 to remove the guides 300 from the guides 304 and 323 of the drill tool 301 and the operating handle 320, thereby detaching the drill tool 301 and the operating handle 320 from the guides 300. Then, the operator pulls the drill tool 301 out of the connecting section 321 of the operating handle 320 while resisting the locking mechanism 321b, thereby detaching the drill tool 301 from the operating handle 320 and completing the machining of the pilot hole H.

[0080] In the process of forming the pilot hole H, the operator attached the drill tool 301 to the operating handle 320, then passed the guide tool 300 through the drill tool 301 and the operating handle 320, and after removing it from the guide tool 300, removed the drill tool 301 from the operating handle 320. However, the operator may also pass the guide tool 300 through each drill tool 301 and operating handle 320 before attaching the drill tool 301 to the operating handle 320, or remove the drill tool 301 from the operating handle 320 while the guide tool 300 is still through it, and then remove the guide tool 300 from each of the drill tool 301 and operating handle 320, respectively.

[0081] Next, as the fourth step, the operator performs shaping of the pilot hole H. Here, shaping of the pilot hole H is a process to shape the pilot hole H formed in the third step with greater precision. Specifically, as shown in Figure 18, the operator attaches the milling tool 305 to the operating handle 320 in the same manner as the drill tool 301, and then inserts the milling part 306 into the pilot hole H while rotating it in the same manner as the drill tool 301 to cut (mill) the inner surface of the pilot hole H. After the operator has finished milling the pilot hole H, the operator detaches the milling tool 305 and the operating handle 320 from the guide tool 300 in the same manner as the drill tool 301, and then removes the milling tool 305 from the operating handle 320 to complete the shaping of the pilot hole H.

[0082] Through these third and fourth steps, in this embodiment, a bottomed hole is formed in the middle phalanx bone I, with the inner diameter of the pilot hole H widening in a funnel shape on the opening side. Note that the shaping of the pilot hole H in this fourth step can be omitted if a sufficient pilot hole H for the installation of the stem 101 has been formed by the shaping of the pilot hole H in the third step.

[0083] Next, the worker performs the fifth step, which is the implantation of the stem 101. Here, the implantation of the stem 101 is the process of setting the stem 101 into the pilot hole H formed in the middle phalanx bone I. Specifically, as shown in Figure 19, the worker attaches the implant tool 310 to the operating handle 320 in the same manner as the drill tool 301. Then, the worker positions the stem 101 through the through hole 103 of the stem 101, passing the guide tool 300 that extends from the pilot hole H to the outer circumference of the guide tool 300.

[0084] Next, the operator inserts a guide tool 300, which penetrates the stem 101, into the guide holes 314 and 323 of the implant tool 310 and the operating handle 320, respectively, and fits the implant-side fitting portion 311 of the implant tool 310 onto the stem-side fitting portion 110 of the stem 101. Then, the operator rotates the operating handle 320 to rotate the entire implant tool 310, thereby rotating the stem 101 and screwing it into the middle phalanx bone I while tapping.

[0085] In this case, the worker screws the stem 101 into the middle phalanx I until the end face of the stem-side fitting portion 110 of the stem 101 is substantially flush with the surface of the sliding body mounting surface S of the middle phalanx I. The worker also positions the rotational position (orientation) of the stem 101 at the position (orientation) of the stem-side fitting portion 110 in the circumferential direction (rotational direction) of the stem 101, which positions the tip sliding body 120 in the appropriate orientation relative to the distal phalanx D when the tip sliding body 120 is attached to the stem 101. During this screwing operation of the stem 101, the implant device 310 and the operating handle 320 rotate around the guide device 300 as the center of rotation because the guide device 300 passes through it, allowing the stem 101 to be screwed in along the guide device 300 within the middle phalanx I.

[0086] Next, once the worker has screwed the stem 101 to a predetermined position within the middle phalanx bone I, the worker operates the operating handle 320 to remove the implant-side fitting portion 311 of the implant device 310 from the stem-side fitting portion 110 of the stem 101, thereby detaching the implant device 310 from the stem 101. Then, the worker detaches the implant device 310 and the operating handle 320 from the guide device 300 in the same manner as with the drill device 301, and then removes the implant device 310 from the operating handle 320 to complete the implantation work of the stem 101.

[0087] Next, as the sixth step, the worker performs a surface finishing process on the sliding body mounting surface S. Here, the surface finishing process on the sliding body mounting surface S is a process in which both or one of the sliding body mounting surface S of the middle phalanx bone I and the end face on the stem-side fitting portion 110 side of the stem 101 screwed into the pilot hole H are cut to make them flush. Specifically, as shown in Figure 20, the worker attaches the surface finishing tool 315 to the operating handle 320 in the same manner as the drill tool 301, and then positions the surface finishing tool 315 and the operating handle 320 on the outer circumference of the guide tool 300 in the same manner as the drill tool 301, and positions the surface finishing portion 316 of the surface finishing tool 315 facing the sliding body mounting surface S.

[0088] Next, the operator rotates the operating handle 320 to rotate the surface-finishing part 316 and bring it into contact with the sliding body mounting surface S and / or the end face of the stem 101, thereby cutting them to make them flush. After the operator has finished cutting the sliding body mounting surface S and / or the end face of the stem 101, the operator can detach the surface-finishing tool 315 and the operating handle 320 from the guide tool 300 in the same manner as with the drill tool 301, and then remove the surface-finishing tool 315 from the operating handle 320 to complete the surface-finishing process.

[0089] As a result, the sliding body mounting surface S on the middle phalanx bone I and the end face of the stem 101 screwed into the pilot hole H are formed flush. However, this sixth step of surface finishing can be omitted if the sliding body mounting surface S and the end face of the stem 101 screwed into the pilot hole H are already flush as a result of the fifth step, or if there is little need for them to be flush.

[0090] Next, as the seventh step, the worker removes the guide tool 300. Specifically, the worker can remove the guide tool 300 from the pilot hole H and the stem 101 by pulling out the guide tool 300 that extends from the through hole 103 of the stem 101 which is inserted into the pilot hole H. In this case, the worker can remove the guide tool 300 from the middle phalanx bone I while rotating it around its axis or without rotating it.

[0091] Next, the worker performs the eighth step, which is the femoral head resection. Here, the femoral head resection is the process of removing a portion of the femoral head (shown by the dashed line in Figure 21) to prevent the sliding body 121 from physically interfering with the femoral head of the middle phalanx I when the tip sliding body 120 is attached to the stem 101, as shown in Figure 21. This femoral head resection is a known procedure using a known cutting tool, so a detailed explanation is omitted. Note that the femoral head resection in the eighth step can be omitted if it is not necessary to remove the femoral head of the middle phalanx I.

[0092] Next, as the ninth step, the worker installs the tip sliding body 120. Specifically, the worker prepares the tip sliding body 120, orients it appropriately with respect to the distal phalanx D, and then fits the sliding body side fitting portion 130 into the stem side fitting portion 110 of the stem 101. Then, the worker uses a tool such as a hammer to strike the curved portion 121a of the sliding body body 121 on the stem 101, thereby striking the sliding body side fitting portion 130 towards the stem side fitting portion 110. In this case, since the sliding body side fitting portion 130 is formed in a tapered shape in which the cross-sectional shape continuously increases from the tip to the base, it is fitted while expanding the slit 111 of the stem side fitting portion 110.

[0093] In other words, the tip sliding body 120 is firmly fitted by the wedge effect generated between the sliding body side fitting portion 130 and the stem side fitting portion 110. Furthermore, the stem 101's fixing force to the middle phalanx I increases because the stem side fitting portion 110 also elastically deforms outward. In addition, the tip sliding body 120 is prevented from rotating circumferentially relative to the stem 101 by the cross-shaped sliding body side fitting portion 130. As a result, the worker can attach the middle phalanx artificial joint 100 to the middle phalanx I.

[0094] Next, the worker attaches the distal phalanx artificial joint 200 to the distal phalanx D. The procedure for attaching the distal phalanx artificial joint 200 to the distal phalanx D is the same as the procedure for attaching the middle phalanx artificial joint 100 to the middle phalanx I described above, so the explanation is omitted. In addition, the femoral head resection procedure described in step 8 above is not necessary when attaching the distal phalanx artificial joint 200 to the distal phalanx D.

[0095] Next, the surgeon abuts the tip sliding body 120 of the middle phalanx artificial joint 100 attached to the middle phalanx I and the tip sliding body 220 of the distal phalanx artificial joint 200 attached to the distal phalanx D in a state where they can slide against each other to form an artificial DIP joint. After that, the surgeon closes the incised areas in the fingers, including the middle phalanx I and distal phalanx D, by suturing, and completes the surgery. The procedure for closing the incisions after the attachment of the middle phalanx artificial joint 100 and the distal phalanx artificial joint 200 is publicly known, so its explanation is omitted.

[0096] Next, we will describe the removal procedure for the middle phalanx artificial joint 100 attached to the middle phalanx I or the distal phalanx artificial joint 200 attached to the distal phalanx D. In this case, since the removal procedure for the middle phalanx artificial joint 100 from the middle phalanx I and the removal procedure for the distal phalanx artificial joint 200 from the distal phalanx D are similar, we will describe the removal procedure for the middle phalanx artificial joint 100 from the middle phalanx I.

[0097] The removal of the middle phalanx artificial joint 100 can occur in several ways: first, when the middle phalanx artificial joint 100 is removed by making an incision in the finger due to circumstances after it has been fully implanted; and second, when the middle phalanx artificial joint 100 is removed from the middle phalanx I during the implantation process (i.e., during surgery) for some reason. A physician or other worker performing the removal of the middle phalanx artificial joint 100 from the middle phalanx I first prepares the removal tool 330 and the operating handle 320, respectively.

[0098] The removal tool 330 is an instrument for removing the stem 101 attached to the middle phalanx I, and is constructed by forming a metal or resin material into a rod shape. More specifically, as shown in Figure 23, the removal tool 330 mainly comprises a connecting portion 331, a stopper portion 332, and a handle portion 333.

[0099] The connecting portion 331 is a part that screws into the female threaded portion 104 formed inside the stem 101, and is constructed by forming a male thread on the surface of the round bar. In this case, the male thread constituting the connecting portion 331 is a male thread that screws into the male threaded portion 105, that is, it is a reverse thread with respect to the male threaded portion 105 of the stem 101. Furthermore, this connecting portion 331 is formed to be longer than the axial length of the female threaded portion 104.

[0100] As shown in Figure 24, the abutment portion 332 is the part that abuts against the end of the stem body 102 on the stem side fitting portion 110 when the connecting portion 321 is screwed into the female thread portion 104 of the stem 101, and is formed in the shape of a disc that can abut against that end. This abutment portion 332 is formed between the connecting portion 321 and the handle portion 333.

[0101] The handle portion 333 is the part that supports the connecting portion 331 and the abutment portion 332, respectively, and is formed as a straight rod. The connecting portion 331 is provided at one end of the handle portion 333, protruding axially via the abutment portion 332, and the other end portion has a handle mounting portion 333a for detachably attaching the operating handle 320. In this embodiment, the handle mounting portion 333a is composed of a D-cut surface, which is created by cutting out a part of the round rod-shaped handle portion 333 in a flat surface in the axial direction to give it a D-shaped cross-section, and a groove portion that extends circumferentially in a concave shape in the circular portion of the cross-section. These connecting portion 331, abutment portion 332, and handle portion 333 are integrally formed from a round rod-shaped stainless steel material.

[0102] First, if an incision is necessary in the finger to be treated when removing the middle phalanx artificial joint 100, the worker will perform the incision to expose the DIP joint. Also, when removing the middle phalanx artificial joint 100, if the tip sliding body 120 is connected to the stem 101, the worker will remove the tip sliding body 120 from the stem 101. Specifically, the worker can remove the tip sliding body 120 by grasping it and pulling it out from the stem 101.

[0103] Next, as the first step, the operator connects the connecting portion 331 of the extraction tool 330 to the female threaded portion 104 of the stem 101. Specifically, as shown in Figure 24, the operator attaches the extraction tool 330 to the operating handle 320 in the same manner as the drill tool 301, and then rotates the operating handle 320 to screw-fit the connecting portion 331 into the female threaded portion 104 of the stem 101. In this case, the operator screws the connecting portion 331 into the female threaded portion 104 until the abutting portion 332 abuts against the end of the stem-side fitting portion 110 on the stem 101 and rotation becomes impossible.

[0104] Next, as the second step, the worker removes the stem 101 from inside the middle phalanx bone I. Specifically, the worker rotates the operating handle 320 in the same direction as the first step to further rotate the connecting part 331 in the same direction as the first step, thereby applying a rotational force to the stem 101 in the same direction as the rotation of the connecting part 331. In this case, since the stem 101 is screw-fitted to the middle phalanx bone I by a male screw part 105 which is configured with a reverse thread to the female screw part 104, the rotational force acting via the female screw part 104 causes the male screw part 105 to start rotating in a direction that loosens the screw-fit of the male screw part 105 to the middle phalanx bone I. Therefore, the worker can remove the stem 101 from inside the middle phalanx bone I by continuing to rotate the operating handle 320.

[0105] When the worker has removed the stem 101 from the middle phalanx I, they can remove the removal tool 330 from the operating handle 320 in the same manner as with the drill tool 301, thereby completing the removal of the stem 101. In addition, during this removal of the stem 101, the worker can also remove the stem 101 from the middle phalanx I by directly gripping and rotating the removal tool 330 without connecting it to the operating handle 320.

[0106] As can be understood from the above description of operation, according to the first embodiment, the artificial joint 100 for the middle phalanx has a stem 101 that is inserted into the middle phalanx I, which is at least one of the pair of bones that make up the DIP joint, and a tip sliding body 120 that indirectly slides against the other bone, the distal phalanx D, to form a joint. These are directly connected by a stem-side fitting portion 110 or a sliding body-side fitting portion 130, which are formed on each of these parts. This reduces the burden of the installation work on the middle phalanx I that makes up the DIP joint, and improves the durability or reliability of the DIP joint after installation. Furthermore, according to the first embodiment, the artificial joint 200 for the distal phalanx exhibits the same effects as the artificial joint 100 for the middle phalanx.

[0107] <Second Embodiment> (Description of the 400-unit artificial joint for the middle phalanx) Next, an artificial joint 400 for the middle phalanx according to a second embodiment of the present invention will be described with reference to Figures 25 to 31. In describing the artificial joint 400 for the middle phalanx according to this second embodiment, the focus will be on the parts that differ from the artificial joint 100 for the middle phalanx in the first embodiment described above, and the parts that are common to both embodiments and corresponding parts will be omitted as appropriate. This artificial joint 400 for the middle phalanx, like the artificial joint 100 for the middle phalanx described above, is mainly composed of a stem 401 and a tip sliding body 420.

[0108] The stem 401 comprises a stem body 402, a through hole 403 (fitting portion side hole 403a, main hole 103b), a female thread portion 104, a male thread portion 105, and a stem-side fitting portion 410, which correspond to the stem body 102, through hole 403 (fitting portion side hole 403a, main hole 403b), female thread portion 404, male thread portion 405, and stem-side fitting portion 410, respectively, in the stem 101. The stem 401 differs from the first embodiment in that the female thread portion 404 is formed over the entire area of ​​the main hole portion 403b, and the configuration of the stem-side fitting portion 410 differs from that of the stem-side fitting portion 110. Specifically, the stem-side fitting portion 410 is configured to include a convex first portion 411 and a concave second portion 412, as shown in Figures 25 and 26, respectively.

[0109] The convex first portion 411 is the part into which the concave first portion 431 of the tip sliding body 420 fits, and is formed extending axially in a cylindrical shape from the end of the male threaded portion 105 at one end (upper side in the figure) of the stem body 402. In this case, the convex first portion 411 is formed with an outer diameter smaller than the outer diameter of the male threaded portion 105, and is formed in a tapered shape in which the outer diameter continuously decreases from the male threaded portion 105 side toward the tip. In this embodiment, the convex first portion 411 is formed in a 3° tapered shape. Furthermore, the inner circumference of the convex first portion 411 constitutes the fitting portion side hole 403a and has a female threaded portion 404 formed therein.

[0110] The concave second portion 412 is the part of the tip sliding body 420 into which the convex second portion 432 fits. Four concave grooves are formed on the outer circumferential surface of the convex first portion 411, each extending axially and evenly spaced in the circumferential direction. One end (upper side in the figure) of the concave second portion 412 opens to the end of the stem body 402, while the other end (lower side in the figure) extends to the male threaded portion 105. In this embodiment, the portion of the concave second portion 412 that has the male threaded portion 105 formed on it is longer than the portion formed on the convex first portion 411.

[0111] The tip sliding body 420 includes a sliding body body 421 (curved surface portion 421a, base portion 421b) and a sliding body side fitting portion 430, which correspond to the sliding body body 121 (curved surface portion 121a, base portion 121b) and sliding body side fitting portion 130 of the tip sliding body 120, respectively. The configuration of the sliding body side fitting portion 430 of this tip sliding body 420 differs from that of the sliding body side fitting portion 130. Specifically, the sliding body side fitting portion 430 is configured to include a concave first portion 431 and a convex second portion 432, as shown in Figures 25 and 27, respectively.

[0112] The concave first portion 431 is the part of the stem 401 that fits into the convex first portion 411, and the concave bottomed cylindrical body into which the convex first portion 411 fits is formed protruding from the base portion 421b. In this case, the concave first portion 431 is formed with a constant inner diameter that is smaller than the maximum outer diameter of the convex first portion 411. Furthermore, the concave first portion 431 is formed to a depth that allows the convex first portion 411 to fit completely.

[0113] The convex second portion 432 is the part that fits into the concave second portion 412 of the stem 401. Four convex projections are formed at the end of the concave first portion 431, each fitting into one of the four concave second portions 412, with the projections evenly spaced in the circumferential direction and extending axially. In this case, the convex second portion 432 is formed to a length that extends to the male threaded portion 405 when fitted into the concave second portion 412.

[0114] (Description of milling tool 440 and implant tool 450) Next, we will describe the milling tool 440 and implant tool 450 used for attaching the artificial joint 400 for the middle phalanx to the middle phalanx I, which are configured in this way.

[0115] As shown in Figure 28, the milling tool 440 is equipped with a milling section 441, a handle section 442, a handle section (not shown), and a guide hole 443, which correspond to the milling section 306, handle section 307, handle mounting section 307a, and guide hole 308 of the milling tool 305, respectively. In this case, the milling section 441 differs from the milling section 306 in that it has a second cutting edge 441b between the first cutting edge 441a, which corresponds to the cutting edge of the milling section 306, and the handle section 442. The second cutting edge 441b is a cutting edge for forming a portion that accommodates the concave first section 431 of the tip sliding body 420, and is constructed by forming the cutting edge on the outer circumferential surface of a cylindrical body.

[0116] As shown in Figure 29, the implant device 450 is equipped with an implant-side fitting portion 451, a projection 452, a handle portion 453, a handle mounting portion (not shown), and a guide hole 454, which correspond to the implant-side fitting portion 311, projection 312, handle portion 313, handle mounting portion 313a, and guide hole 314 of the implant device 310, respectively. In this case, the configuration of the implant-side fitting portion 451 and projection 452 of the implant device 450 differs from the configuration of the implant-side fitting portion 311 and projection 312.

[0117] Specifically, the implant-side mating portion 451 is formed by having four convex projections 452 evenly spaced circumferentially and extending axially, which fit into four concave second portions 412 at the end of the cylindrical body through which the guide hole 454 opens. In this case, the projections 452 are formed to a length that extends to the male threaded portion 405 when fitted into the concave second portion 412.

[0118] (Implantation of 400 artificial joint for the middle phalanx) The process of attaching the artificial joint 400 for the middle phalanx, configured in this manner, to the middle phalanx I is the same as in the first embodiment described above, except for some slight differences in the process of forming the pilot hole H in the fourth step and the process of attaching the tip sliding body 420 in the ninth step.

[0119] Specifically, in the fourth step, the pilot hole H is formed by the second cutting edge 441b of the milling tool 440, as shown in Figure 30. As a result, a large-diameter hole capable of accommodating the concave first portion 431 of the tip sliding body 420 is formed near the opening of the pilot hole H formed in the middle phalanx bone I.

[0120] In the installation of the tip sliding body 420 in the ninth step, as shown in Figure 31, the worker strikes the curved portion 421a of the sliding body body 421 on the stem 401 using a tool such as a hammer, thereby striking the sliding body side fitting portion 430 toward the stem side fitting portion 410. As a result, the concave first portion 431 of the sliding body side fitting portion 430 fits onto the outside of the convex first portion 411 of the stem side fitting portion 410, and then the convex second portion 432 fits onto the concave second portion 412 of the stem side fitting portion 410.

[0121] In this case, the sliding body side fitting portion 430 is firmly fitted to the concave first portion 431 because the convex first portion 411 of the stem side fitting portion 410 is tapered, and the convex second portion 432 fits into the concave second portion 412 formed on the outer circumference of the stem body 402, thereby preventing the stem 401 from rotating in the circumferential direction. As a result, the tip sliding body 420 is firmly connected to the stem 401 in a state where it cannot rotate in the circumferential direction. It should be noted that although this second embodiment describes an artificial joint 400 for the middle phalanx, it is naturally applicable to an artificial joint for the distal phalanx as well.

[0122] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible as long as they do not depart from the purpose of the present invention. In the description of the modified examples, the same reference numerals are used for parts that are the same as those in the embodiments described above and are not newly assigned reference numerals. The modified examples shown below mainly describe modifications of the middle phalanx artificial joints 100 and 400, but they can also be similarly applied to the distal phalanx artificial joint 200.

[0123] For example, in the first embodiment described above, a concave stem-side fitting portion 110 is formed on the stem 101, and a convex sliding body-side fitting portion 130 that fits into the stem-side fitting portion 110 is formed on the tip sliding body 120. In the second embodiment described above, a convex stem-side fitting portion 410 is formed on the stem 401, and a concave sliding body-side fitting portion 430 that fits into the stem-side fitting portion 410 is formed on the tip sliding body 420. As shown above, the stem-side fitting portion can be formed in a concave or convex shape, and the sliding body-side fitting portion can be formed in a convex or concave shape that fits into the stem-side fitting portion.

[0124] Furthermore, in the first embodiment described above, the stem-side fitting portion 110 and the sliding body-side fitting portion 130 were formed with a cross-shaped cross section. Furthermore, in the second embodiment described above, the stem-side fitting portion 410 was formed with a groove-shaped concave second portion 412 recessed into the outer circumferential surface of a cylindrical convex first portion 411, thereby creating an overall non-circular cross section. In this way, by forming the cross section of the stem-side fitting portion and the sliding body-side fitting portion into a polygonal or gear-shaped non-circular shape, relative rotational displacement (orientation deviation) around the axial direction between the stems 101, 401 and the tip sliding bodies 120, 420 can be prevented, and the orientation of the mounting of the tip sliding bodies 120, 420 to the stems 101, 401 around the axial direction can be changed in stages. In this case, the orientation of the tip sliding bodies 120 and 420 can be precisely defined by making the stem-side fitting portion 110 and the sliding body-side fitting portion 130 into a polygonal or gear-shaped cross-section with eight or more vertices in the circumferential direction.

[0125] For example, the stem 460 shown in Figure 32 can be configured by replacing the groove-shaped concave second portion 412 in the stem 401 of the second embodiment with a slit-shaped concave second portion 461. With this configuration, the stem 460 can suppress a decrease in the fitting force between the convex second portion 411 and the concave first portion 431 because the convex second portion 432 is inserted into the concave second portion 461, thereby restricting the radial inward tilting of the convex first portion 411 with which the concave first portion 431 is fitted.

[0126] In this case, the slit-shaped concave second part 461 can be formed in a tapered shape, where the groove width is continuously narrowed from the tip side towards the axial depth side, and / or the thickness of the convex second part 432 that fits into the concave second part 461 is continuously increased from the tip side towards the base side. According to this, the stem 460 can be made to have a more controlled radial inward tilt of the convex first part 411 into which the concave first part 431 is fitted, as the convex second part 432 is inserted into the concave second part 461, thereby improving the fitting force between the convex first part 411 and the concave first part 431.

[0127] Furthermore, for example, the artificial joint 500 for the middle phalanx shown in Figure 33 comprises a stem 501 having a convex stem-side fitting portion 503 with 12 sides, and a tip sliding body 510 having a concave sliding body-side fitting portion 512 with 12 sides.

[0128] Stem 501 is a component corresponding to stems 101 and 401, respectively. It is formed by creating a stem-side fitting portion 503, a male thread portion 504, and an auxiliary support piece 505 from one end to the other of a cylindrical stem body 502. The stem body 502 also has through holes 506 corresponding to through holes 103 and 403.

[0129] The stem-side fitting portion 503 is a component corresponding to the stem-side fitting portions 110 and 410, respectively, and is composed of a convex projection in which 12 concave curves are connected in a ring shape. In other words, although the stem-side fitting portion 503 is not strictly polygonal or gear-shaped, it is formed in a substantially polygonal or spline shape like a gear, in which each of the 12 sides is connected in a ring via 12 vertices. Furthermore, in this embodiment, the stem-side fitting portion 503 is formed in a tapered shape in which the thickness continuously increases from the tip side to the root (male thread portion 504) side.

[0130] The male threaded portion 504 is a component corresponding to the male threaded portions 105 and 405, respectively, and is formed in a tapered shape in which the outer diameter continuously decreases from the stem-side fitting portion 503 towards the auxiliary support piece 505.

[0131] The auxiliary support piece 505 is a component for stabilizing the stem 501 within the middle phalanx bone I, and consists of two curved pieces extending axially from the end of the male threaded portion 504 of the stem body 502.

[0132] The tip sliding body 510 is a component corresponding to the tip sliding bodies 120 and 420, respectively, and is composed of a sliding body body 511 and a sliding body side fitting portion 512. The sliding body body 511 is the part corresponding to the sliding body bodies 121 and 421, and is composed of curved portions 511a and 511b similar to the curved portions 121a and 421a and the base portions 121b and 421b, respectively.

[0133] The sliding body side fitting portion 512 corresponds to the sliding body side fitting portions 130 and 430, respectively, and is composed of a concave, bottomed hole into which the stem side fitting portion 503 fits. In other words, although the sliding body side fitting portion 512 is not strictly polygonal or gear-shaped, it is formed in a substantially polygonal or spline shape like a gear, in which each of the 12 sides is connected in a ring via 12 vertices. Furthermore, in this embodiment, the sliding body side fitting portion 512 is formed to have a constant thickness from the opening side to the inner side.

[0134] The artificial joint 500 for the middle phalanx, configured in this manner, is attached to the middle phalanx I in the same manner as in each of the embodiments described above. Specifically, the worker forms a pilot hole H in the middle phalanx I, and then screws the stem 501 into this pilot hole H. In this case, the worker screws the stem 501 into the middle phalanx I until the end face of the stem-side fitting portion 503 of the stem 501 is flush with the sliding body mounting surface S in the middle phalanx I.

[0135] Next, the worker strikes the tip sliding body 510 against the stem 501 screwed into the middle phalanx bone I, thereby driving the sliding body side fitting portion 512 into the stem side fitting portion 503. In this case, since the stem side fitting portion 503 is formed in a tapered shape in which the cross-sectional shape expands continuously from the tip side to the base side, the sliding body side fitting portion 512 fits firmly, and the stem side fitting portion 503 and the sliding body side fitting portion 512 are formed to protrude radially, preventing the stem 501 from rotating in the circumferential direction. As a result, the tip sliding body 510 is firmly connected to the stem 501 in a state where it cannot rotate in the circumferential direction.

[0136] Furthermore, when installing the artificial joint 500 for the middle phalanx onto the middle phalanx I, drilling tools, milling tools, implanting tools, and surface preparation tools (not shown) corresponding to the shapes of the stem 501, the stem-side fitting portion 503, and the sliding body-side fitting portion 512 are used. In addition, the present invention does not preclude forming the cross-sectional shapes of the stem-side fitting portion and the sliding body-side fitting portion into a perfectly circular shape.

[0137] Furthermore, in the first embodiment described above, the sliding body side fitting portion 130 is formed in a tapered shape, with its thickness increasing from the tip side towards the root side. Furthermore, in the second embodiment described above, the stem side fitting portion 410 is formed in a tapered shape, with its thickness increasing from the tip side towards the male thread portion 405 side. In this case, in the first embodiment described above, the stem side fitting portion 110 can also be formed in a tapered shape, with the width of the cross groove continuously narrowing from the tip side towards the back side. Furthermore, in the second embodiment described above, the sliding body side fitting portion 430 can also be formed in a tapered shape, with the inner diameter of the concave first portion 431 continuously decreasing from the opening side towards the back side. However, the stem side fitting portion and the sliding body side fitting portion can also be formed in a shape with a constant thickness, outer diameter, or inner diameter.

[0138] Furthermore, in each of the above embodiments, the stems 101, 401 are cylindrical bodies in their entirety, tapered in shape with an outer diameter that continuously decreases towards the direction of insertion into the middle phalanx I, and male threaded portions 105, 405 are formed on the entire outer circumference of the cylindrical body constituting the stems 101, 401. As a result, the artificial joints 100, 400 for the middle phalanx can be firmly connected to the middle phalanx I by screw-fitting over the entire axial range. However, the stems 101, 401 can also be configured in a manner in which the tip of the cylindrical body is divided into two parts, as in the prior art or as shown in Figure 33, or in which the male threaded portions 105, 405 are formed only on a part of the outer circumference of the stems 101, 401, rather than the entire circumference. Also, the male threaded portions 105, 405 may be ordinary male threads that are fitted into pre-formed female threads, rather than tapping threads. Furthermore, the stems 101, 401 may be formed in a straight shape with a constant outer diameter along their entire length.

[0139] Furthermore, in each of the above embodiments, the stems 101 and 401 are constructed with through holes 103 and 403 for passing the guide device 300 through. However, the stems 101 and 401 can be constructed without the through holes 103 and 403 if the guide device 300 is not used. That is, the stems 101 and 401 can be formed into a solid rod shape instead of a cylindrical rod shape. In this case, the stems 101 and 401 can be screwed directly into the medullary cavity MC, either directly into the pilot hole H formed in the middle phalanx I or without forming the pilot hole H.

[0140] Furthermore, when the stems 101 and 401 are constructed as cylindrical bodies, the guide tool 300 is used only when forming a pilot hole H within the middle phalanx bone I. When screwing the stems 101 and 401 into the pilot hole H, the guide tool 300 can be removed and the stems 101 and 401 can be screwed into the pilot hole H without using the guide tool 300.

[0141] Furthermore, in each of the above embodiments, the worker screwed in the stems 101 and 401 after forming a pilot hole H in the middle phalanx I. However, the worker can also screw in the stems 101 and 401 directly into the medullary cavity MC with the guide device 300 inserted directly without forming a pilot hole H in the middle phalanx I, or without placing the guide device 300.

[0142] Furthermore, in each of the above embodiments, the stems 101 and 401 are configured with female threaded portions 104 and 404 for connecting the extraction tool 330. However, the stems 101 and 401 can be configured without the female threaded portions 104 and 404 if extraction from the middle phalanx bone I of the stems 101 and 401 is not considered. In this case, the through hole 103 can be formed with a cross-sectional shape other than a perfect circle (for example, an elliptical shape, a square shape, or other polygonal shape).

[0143] Furthermore, in the first embodiment described above, the female thread portion 104 was formed over a range of approximately half the length of the main body hole portion 103b in the through hole 103. Furthermore, in the second embodiment described above, the female thread portion 404 was formed over the entire area of ​​the fitting portion side hole portion 403a and the entire area of ​​the main body hole portion 103b in the through hole 403. In other words, the female thread portions 104 and 404 can be formed over any length within the total length range of the through holes 103 and 403.

[0144] Furthermore, in each of the above embodiments, the drill tool 301, milling tools 305, 440, implant tools 310, 450, surface preparation tool 315, and removal tool 330 are configured to be operated manually by connecting a separately constructed operating handle 320. However, the drill tool 301, milling tools 305, 440, implant tools 310, 450, surface preparation tool 315, and removal tool 330 can also be constructed by integrally forming the portion corresponding to the operating handle 320.

[0145] Furthermore, in each of the above embodiments, the operator manually operated the drill tool 301, milling tools 305, 440, implant tools 310, 450, surfacer tool 315, and removal tool 330 by connecting a separately constructed operating handle 320 to them to perform cutting of the middle phalanx bone I, installation of the stems 101, 401, or removal of the stems 101, 401. However, the operator can also directly manually operate the drill tool 301, milling tools 305, 440, implant tools 310, 450, surfacer tool 315, and removal tool 330 without connecting the operating handle 320, or they can be used by attaching the drill tool 301, milling tools 305, 440, implant tools 310, 450, surfacer tool 315, and removal tool 330 to an electric drill or other power tool.

[0146] Furthermore, in each of the above embodiments, the removal tool 330 is configured to abut against the ends of the stems 101 and 401 by including a stopper portion 332, causing the stems 101 and 401 to rotate together with the connecting portion 331. However, the removal tool 330 can also be configured without the stopper portion 332. In this case, the removal tool 330 can also be configured so that the connecting portion 331 is long enough to reach the innermost part of the female threaded portion 104 and 404 (the end of the female threaded portion 104 and 404), causing the stems 101 and 401 to rotate together with the connecting portion 331.

[0147] Furthermore, in each of the above embodiments, the through holes 103, 403, 506 and the guide holes 304, 308, 314, 318, 323, 443, and 454 were each formed with a circular cross-sectional shape. However, each of these holes can be formed with a cross-sectional shape other than a circular shape, for example, an elliptical shape, a square shape, or other polygonal shape. Similarly, the guide tool 300 can also be formed with a cross-sectional shape other than a circular shape, for example, an elliptical shape, a square shape, or other polygonal shape. Moreover, the through holes 103, 403, 506 and the guide holes 304, 308, 314, 318, 323, 443, and 454 only need to be formed to be the same size as the diameter of the guide tool 300 in whole or in part within the through holes.

[0148] Furthermore, in each of the above embodiments, the artificial joint was configured as a middle phalanx artificial joint 100, 400 or a distal phalanx artificial joint 200 attached to the middle phalanx I or distal phalanx D that constitute the DIP joint. However, the artificial joint according to the present invention can be broadly applied to joints other than the DIP, such as the carpometacarpal joint (CM joint), metacarpophalangeal joint (MP joint), interphalangeal joint (IP joint), or proximal interphalangeal joint (PIP joint), as well as to joints other than the fingers.

[0149] Furthermore, in each of the above embodiments, the middle phalanx artificial joints 100 and 400 are attached to the middle phalanx I, which is a pair of bones constituting the DIP joint, and the distal phalanx artificial joint 200 is attached to the distal phalanx D. As a result, the distal phalanx D slides indirectly with the middle phalanx artificial joints 100 and 400 via the distal phalanx artificial joint 200, and the middle phalanx I slides indirectly with the distal phalanx artificial joint 200 via the middle phalanx artificial joints 100 and 400. However, the artificial joint according to the present invention does not need to be attached to both of the pair of bones constituting the joint, the middle phalanx I and the distal phalanx D in the above embodiments, and can be used by attaching it to only one of the bones. In this case, the distal phalanx D slides directly with the middle phalanx artificial joints 100 and 400 without going through the distal phalanx artificial joint 200, and the middle phalanx I slides directly with the distal phalanx artificial joint 200 without going through the middle phalanx artificial joints 100 and 400. [Explanation of Symbols]

[0150] I...Middle phalanx, D...Distal phalanx, H...Lower hole, MC...Bone marrow cavity, S...Sliding surface 100... Artificial joint for the middle phalanx, 101...Stem, 102...Stem body, 103...Through hole, 103a...Side hole of the fitting part, 103b...Hole of the main body, 104...Female thread part, 105...Male thread part, 110... Stem side fitting part, 111... Slit, 120...Tip sliding body, 121...Sliding body body, 121a...Curved surface part, 121b...Base part 130...Sliding body side fitting portion, 131...Projection piece, 200... Artificial joint for distal phalanx, 201...Stem, 202...Stem body, 203...Through hole, 203a...Side hole of the fitting part, 203b...Hole of the main body, 204...Female thread part, 205...Male thread part 210... Stem-side fitting portion, 211... Slit, 220...Tip sliding body, 221...Sliding body body, 221a...Curved surface part, 221b...Base part 230...Sliding body side fitting portion, 231...Projection piece, 300... Guide tool, 301...Drill tool, 302...Drill part, 303...Handle part, 303a...Handle mounting part, 304...Guide hole, 305...Milling tool, 306...Milling section, 307...Handle section, 307a...Handle mounting section, 308...Guide hole, 310...implant device, 311...implant-side mating part, 312...projection piece, 313...handle part, 313a...handle mounting part, 314...guide hole, 315... Surface finishing tool, 316... Surface finishing part, 317... Handle part, 317a... Handle mounting part, 318... Guide hole, 320...Operating handle, 321...Connecting part, 321a...Fitting part, 321b...Locking mechanism, 322...Operating part, 323...Guide hole, 330...Removal tool, 331...Connecting part, 332...Button part, 333...Handle part, 333a...Handle mounting part, 400... Artificial joint for the middle phalanx, 401...Stem, 402...Stem body, 403...Through hole, 403a...Side hole of the fitting part, 403b...Hole of the main body, 404...Female thread part, 405...Male thread part 410... Stem-side fitting portion, 411... Convex first portion, 412... Concave second portion, 420...Tip sliding body, 421...Sliding body body, 421a...Curved surface part, 421b...Base part 430...Sliding body side fitting portion, 431...Concave first portion, 432...Convex second portion, 440...Milling tool, 441...Milling section, 441a...First cutting edge, 441b...Second cutting edge, 442...Handle section, 443...Guide hole, 450...Implant device, 451...Implant-side mating part, 452...Projection piece, 453...Handle part, 454...Guide hole, 460... Stem, 461... Concave second part, 500... Artificial joint for the middle phalanx, 501...Stem, 502...Stem body, 503...Stem side fitting part, 504...Male threaded part, 505...Auxiliary support piece, 506...Through hole 510...Tip sliding body, 511...Sliding body body, 511a...Curved surface, 511b...Base, 512...Sliding body side fitting part.

Claims

1. An artificial joint that is attached between a pair of bones that make up a joint, A stem formed in the shape of a rod and inserted into at least one of the pair of bones with one of its ends exposed, The stem comprises a tip sliding body provided at one of its exposed ends, which slides directly or indirectly against the other bone in the pair of bones, thereby changing the relative angle between the two bones in the pair of bones. The aforementioned stem is, The exposed end has a stem-side fitting portion formed in a concave or convex shape, The aforementioned tip sliding body is An artificial joint characterized by having a sliding body side fitting portion that is formed in a convex or concave shape and fits into the stem side fitting portion.

2. In the artificial joint described in claim 1, The stem-side fitting portion and the sliding body-side fitting portion are An artificial joint characterized by having a polygonal or gear-like cross-sectional shape.

3. In the artificial joint described in claim 1, The stem-side fitting portion and the sliding body-side fitting portion are An artificial joint characterized by a tapered shape that provides a stronger fit as the mating depth increases.

4. In the artificial joint described in claim 1, One of the stem-side fitting portion and the sliding body-side fitting portion is, A convex first part formed in the shape of a rod or cylinder, The convex first portion has a concave second portion that extends in a groove-like or slit-like manner along the fitting direction. The other of the stem-side fitting portion and the sliding body-side fitting portion is, A cylindrical concave first part that fits onto the outside of the convex first part, An artificial joint characterized by having a concave first portion and a convex second portion that extends convexly along the fitting direction and fits into the concave first portion.

5. In the artificial joint described in claim 4, The concave second portion and the convex second portion are, An artificial joint characterized by a tapered shape that provides a stronger fit as the mating depth increases.

6. In the artificial joint described in claim 1, The aforementioned stem is, An artificial joint characterized in that the entire body is cylindrical, and is tapered in a way that the outer diameter continuously decreases in the direction of insertion into one of the bones, and male threads are formed on the outer surface of the cylindrical body.

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