Intramedullary nails and bone grafting devices

Abstract

The intramedullary nail (1) comprises: a nail body (10) having formed on its inner circumferential surface a "first female threaded area (15) forming a cylinder", a "second female threaded area (16) disposed on the base end (Da) side relative to the first female threaded area (15)" and a "non-threaded area (17) disposed between the first female threaded area (15) and the second female threaded area (16)"; and a limiting body (20) lockable to the first female threaded area (15) and the second female threaded area (16), wherein the nail body is locked to the first female threaded area (15) and the second female threaded area (16). The limiting position of the female thread field (15) restricts the relative movement and relative rotation of the bone joint shaft member (2) to the nail body (10); the annular body (30), having an annular body-side male thread field (35) that can be locked into the second female thread field (16), is positioned on the base end (Da) side relative to the limiting body (20) which becomes the limiting position, and is positioned in the non-threaded field (17), the forming range of the annular body-side male thread field (35) is smaller than the forming range of the non-threaded field (17).

Description

Technical Field

[0001] The present invention relates to an intramedullary nail and a bone joining device used for bone joining. Prior Art

[0002] Traditionally, fractures near bones such as the thighbone and upper wrist are treated with a surgical instrument called an intramedullary nail. The nail is inserted longitudinally into the bone's medullary cavity. A shaft-like member called a lag screw is then passed through the nail. By locking the shaft into the bone, the nail and the shaft securely secure the fractured bone from the inside.

[0003] Here, for example, as described in Japanese Patent Application Publication No. 2014-512853, after a guide wire is inserted into the medullary cavity of a bone in advance, the guide wire is passed through the intramedullary nail and then the intramedullary nail is inserted into the bone, so that the intramedullary nail is formed into a cylindrical shape.

[0004] Then, a restricting body, also formed in a cylindrical shape and called a set screw, is provided inside the intramedullary nail formed in the above-mentioned cylindrical shape. This restricting body restricts the relative movement or rotation of the shaft member (tension screw) with respect to the intramedullary nail. Summary of the Invention

[0005] [Problems to be solved by the invention]

[0006] However, in conventional intramedullary nails, there is a risk that the restrictor (fixing screw) may move from its designated position due to external factors such as vibration. This can lead to insufficient fixation of the intramedullary nail by the shaft member (tension screw), or the restrictor (fixing screw) may fall out of the intramedullary nail during transportation, resulting in inadequate usability. Improvements are desired in this regard.

[0007] In view of this, the present invention provides: an intramedullary nail and a bone joining device with improved usability.

[0008] One aspect of the intramedullary nail of the present invention is an intramedullary nail that is inserted into a bone when joining a bone and fixes the bone from the inside together with a bone joining shaft member that passes through the intramedullary nail. The intramedullary nail comprises a nail body, a limiting body, and an annular body. The nail body is formed in a cylindrical shape, and has a shaft member through-hole that penetrates the outer peripheral surface and can allow the shaft member for bone joining to pass through, and has formed on its inner peripheral surface: a first female thread area that is arranged on the base end side in the longitudinal direction relative to the shaft member through-hole; a second female thread area that is arranged on the base end side in the longitudinal direction relative to the first female thread area; a non-threaded area that is arranged between the first female thread area and the second female thread area in the longitudinal direction; the limiting body is formed in a cylindrical shape, and has formed on its outer peripheral surface a limiting body that can be locked with the first female thread area and the second female thread area The body-side male threaded area, in the restricted position locked in the aforementioned first female threaded area, presses the aforementioned bone-joining shaft component arranged in the aforementioned shaft component through-hole toward the aforementioned front end side, thereby restricting the relative movement and relative rotation of the bone-joining shaft component to the aforementioned nail body; the aforementioned annular body is formed in a ring shape with the first axis as the center, and has an annular body-side male threaded area formed on its outer peripheral surface that can be locked in the aforementioned second female threaded area, relative to the aforementioned restriction body that becomes the aforementioned restricted position in the use position, at least a part of it is arranged in the aforementioned non-threaded area on the aforementioned base end side; the aforementioned first female threaded area and the aforementioned second female threaded area are formed with the second axis extending in the aforementioned longitudinal direction as the center, and the formation range of the aforementioned annular body-side male threaded area in the direction of the aforementioned first axis is smaller than the formation range of the aforementioned non-threaded area in the direction of the aforementioned second axis.

[0009] Furthermore, in the intramedullary nail, the thickness of the annular body in the first axial direction may be smaller than the forming range of the non-threaded region in the second axial direction.

[0010] Furthermore, in the intramedullary nail, the non-threaded area forms a circular cross-section with the second axis as the center, and the outer diameter of the thread ridge in the male threaded area on the annular body side may be smaller than the inner diameter of the non-threaded area.

[0011] Furthermore, in the intramedullary nail, the inner diameters of the thread ridges in the first female thread region and the second female thread region may be smaller than the inner diameter of the non-thread region.

[0012] In addition, in the above-mentioned intramedullary nail, the aforementioned limiting body side male thread area is formed with the aforementioned third axis as the center, and the formation range of the aforementioned limiting body side male thread area in the direction of the aforementioned third axis can also be larger than the formation range of the aforementioned non-threaded area in the direction of the aforementioned second axis.

[0013] In addition, in the above-mentioned intramedullary nail, the inner circumferential surface of the above-mentioned annular body may also have a tapered annular surface with the above-mentioned first axis as the center, and the inner diameter of the tapered annular surface gradually decreases from one side end of the above-mentioned first axis before becoming the above-mentioned base end side in the above-mentioned use position toward the other side of the first axis.

[0014] In addition, in the above-mentioned intramedullary nail, the above-mentioned limiting body has a limiting body end face facing the above-mentioned base end side in the above-mentioned limiting position, and the above-mentioned annular body may also have: an annular body end face facing the above-mentioned front end side in the above-mentioned use position, and forming a relative direction from the above-mentioned base end side relative to the above-mentioned limiting body end face of the above-mentioned limiting body before becoming the above-mentioned limiting position.

[0015] In addition, in the above-mentioned intramedullary nail, the above-mentioned limiting body is formed into a cylindrical shape with the third axis as the center, and when the above-mentioned first axis and the above-mentioned third axis are arranged on the same axis, the inner peripheral edge of the end face of the above-mentioned limiting body can also be arranged radially outward compared to the inner peripheral edge of the end face of the above-mentioned annular body.

[0016] In addition, in the above-mentioned intramedullary nail, a circular limiting body inner hole "centered on the third axis extending in the aforementioned longitudinal direction in the aforementioned limiting body at the aforementioned limiting position" is formed on the end face of the aforementioned limiting body, and an annular inner hole that is circular with the aforementioned first axis as the center and has a smaller diameter than the aforementioned limiting body inner hole can also be formed on the end face of the aforementioned annular body.

[0017] Furthermore, in the intramedullary nail, the restricting body and the annular body are formed of the same metal material, and the entire area of ​​one of the restricting body end face and the annular body end face can be oriented relative to a partial area of ​​the other in the longitudinal direction.

[0018] In addition, in the above-mentioned intramedullary nail, a locking portion is formed on the inner circumferential surface of the above-mentioned annular body, which is recessed toward the radial outside or protrudes toward the radial inside. When the above-mentioned locking portion is engaged with the engaged portion of the tool, the above-mentioned annular body can also be rotated around the above-mentioned first axis by the above-mentioned tool.

[0019] Furthermore, a bone joining device according to one aspect of the present invention comprises the intramedullary nail and a bone joining shaft member capable of passing through the aforementioned shaft member through-hole of the intramedullary nail. [Effects of the Invention]

[0020] According to the above-mentioned intramedullary nail and bone joining instrument, usability can be improved. Simple diagram description

[0021] FIG1 is a side view showing the entirety of the bone-jointing device according to the embodiment of the present invention installed in the bone of a patient, as shown by a perspective view of the bone. FIG2 is a longitudinal cross-sectional view of an important part of the intramedullary nail of the bone-engaging device, and is a cross-sectional view of the intramedullary nail viewed from the front of the patient's body when the bone-engaging device is in use. FIG3A is a longitudinal sectional view of the nail body of the intramedullary nail, which is a sectional view taken along the same section as FIG2 . FIG3B is a longitudinal sectional view of the intramedullary nail body, viewed from the circumferential direction 180 degrees opposite to FIG3A , that is, a sectional view of the nail body viewed from the rear of the patient's body. FIG. 4A is a side view showing the restraining body of the intramedullary nail, and is a view showing the restraining body as viewed from the front of the patient's body when the bone joining instrument is in use. FIG. FIG. 4B is a side view showing the restrictor of the intramedullary nail, showing the restrictor as viewed from a position offset by 90 degrees in the circumferential direction relative to FIG. 4A . FIG5 is a longitudinal sectional view showing a state in which the limiting body and the annular body of the intramedullary nail are installed in the nail body, and is a sectional view taken along the same section as FIG2 . FIG6A is a diagram showing the annular body of the intramedullary nail, which is a top view of the annular body viewed from the base end side. FIG6B is a diagram showing the annular body of the intramedullary nail, which is the view indicated by arrow A in FIG6A . FIG7 is a perspective view of a special tool for rotating the annular body of the intramedullary nail. Implementation Method

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (Overall structure) As shown in FIG1 , the bone joining device 100 of this embodiment is used, for example, to treat a fracture (femoral neck fracture) near the bone B1 of a patient's femur (hereinafter referred to as the "bone") B. The bone joining device 100 comprises: a rod-shaped intramedullary nail 1, which is inserted into the femur B along the direction in which the femur B extends; a bone joining shaft member (tension screw) 2, which passes through the intramedullary nail 1 in a manner that intersects the longitudinal direction D of the intramedullary nail 1; and an auxiliary shaft member 3, which is provided together with the bone joining shaft member 2 and passes through the intramedullary nail 1.

[0023] (Intramedullary Nail) As shown in FIG2 , the intramedullary nail 1 comprises: a nail body 10, which is inserted into the medullary cavity (inner cavity) of the femur B in a manner extending along the extension direction of the femur B and is formed into a cylindrical shape; a limiting body 20 and an annular body 30, which are arranged on the inner side of the nail body 10; and an end cap 40, which closes the upper opening 10x of the nail body 10.

[0024] (Nail body) As shown in Figures 3A and 3B, the nail body 10 has: a proximal portion 11, which is arranged on the base end Da side of the longitudinal direction D (the upper side when the bone bonding instrument 100 is in use) and extends in the longitudinal direction D; a distal portion 12, which is arranged on the front end Db side of the longitudinal direction D (the lower side when the bone bonding instrument 100 is in use) relative to the proximal portion 11, is integrated with the proximal portion 11, and extends toward the front end Db side in a manner that is bent (or curved) relative to the proximal portion 11.

[0025] The proximal portion 11 has a cylindrical shape centered on the proximal portion axis (second axis) O1 extending in the longitudinal direction D. Furthermore, the inner hole 11a of the proximal portion 11, formed by the inner circumference of the proximal portion 11, exhibits a true circular cross-section centered on the proximal portion axis O1. Near the distal end Db side of the proximal portion 11, which connects to the distal portion 12, the diameter of the proximal portion 11 gradually decreases from one side (the proximal end Da side) of the proximal portion axis O1 toward the other side (the distal end Db side).

[0026] The distal portion 12 has a cylindrical shape centered on the distal portion axis O2, which extends in the longitudinal direction D and intersects the proximal portion axis O1. Furthermore, the distal portion 12 includes an inner bore 12a having a true circular cross-section centered on the distal portion axis O2. Similar to the proximal portion 11, the distal portion 12 gradually tapers from one side (the base end Da side) of the distal portion axis O2 toward the other side (the distal end Db side) near the distal end Db.

[0027] Next, the inner hole 11a of the proximal portion 11 and the inner hole 12a of the distal portion 12 are smoothly connected. These inner holes 11a and 12a extend entirely through the inner side of the nail body 10 in the longitudinal direction D. These inner holes 11a and 12a function to allow a guide cord (not shown) inserted into the medullary cavity to pass through before the nail body 10 is inserted into the medullary cavity.

[0028] Furthermore, a shaft member through-hole 10y is formed in the proximal portion 11 at a position midway in the longitudinal direction D of the nail body 10, extending through the outer peripheral surface. This shaft member through-hole 10y extends with its central axis Oy in a direction intersecting the proximal portion axis O1. Based on the bone joining device 100 in use, the shaft member through-hole 10y extends from below to above, extending from the outside of the patient's body toward the bone B1 via the trochanter B2 of the femur B (see FIG. 1 ).

[0029] Specifically, the shaft member through-hole 10y communicates with the inner hole 11a of the proximal portion 11 and, based on the state of use of the bone joining device 100, penetrates the outer circumference of the nail body 10 at two locations, the inside and the outside of the body across the inner hole 11a. The bone joining shaft member 2 (see FIG. 1 ), which will be described in detail later, passes through this shaft member through-hole 10y.

[0030] In addition, an auxiliary shaft member through-hole 10z is formed in the proximal portion 11, further to the proximal end Da than the shaft member through-hole 10y. Its central axis Oz extends parallel to the central axis Oy of the shaft member through-hole 10y and extends through the outer circumference. Thus, the auxiliary shaft member through-hole 10z communicates with the inner hole 11a of the proximal portion 11 and, based on the bone joining device 100 in use, penetrates the outer circumference of the nail body 10 at two locations, on the inside and outside of the patient's body, across the inner hole 11a.

[0031] The auxiliary shaft member 3, which will be described in detail later, passes through the auxiliary shaft member through-hole 10z. Once the auxiliary shaft member 3 passes through the auxiliary shaft member through-hole 10z, the auxiliary shaft member 3' is arranged parallel to the bone-joining shaft member 2 passing through the shaft member through-hole 10y (see FIG. 1 ).

[0032] Furthermore, a fixture through-hole 12y is formed in the distal portion 12, further toward the distal end Db than the shaft member through-hole 10y. This through-hole 12y extends through the outer circumference of the distal portion 12, oriented in a direction intersecting the longitudinal direction D, or in a direction perpendicular to the distal portion axis O2. Specifically, the fixture through-hole 12y communicates with the inner hole 12a of the distal portion 12 and, when the bone joining device 100 is in use, penetrates the outer circumference of the nail body 10 at two locations, on the inside and outside of the patient's body, across the inner hole 12a. The fixing screw 13, which secures the intramedullary nail 1 to the femur B, is inserted through this fixture through-hole 12y (see FIG. 1 ).

[0033] In addition, on the inner circumferential surface of the proximal portion 11, that is, the inner surface of the inner hole 11a, a first female thread area 15, a second female thread area 16 and a non-threaded area 17 are formed on the base end Da side of the shaft member through hole 10y and the auxiliary shaft member through hole 10z.

[0034] The first female thread region 15 is formed with the proximal end axis O1 as the center. In the first female thread region 15, when the bone joining device 100 is in use, a restricting body 20 (see FIG. 2 ) described in detail later is locked.

[0035] The second female thread region 16 is spaced apart in the direction of the proximal end axis O1 and is positioned further from the proximal end Da than the first female thread region 15. The dimensions and pitch of the thread ridges and grooves of the second female thread region 16 are identical to those of the first female thread region 15. The second female thread region 16 is formed on the distal end Db side of the nail body 10, i.e., the opening end of the inner hole 11a.

[0036] The non-threaded area 17 is located between the first female threaded area 15 and the second female threaded area 16. This area is the area within the inner surface of the inner hole 11a of the proximal portion 11 where no female threads are formed. It is formed by a hole with a true circular cross-section centered on the proximal portion axis O1. The inner diameter of the non-threaded area 17 is the same as, or slightly larger than, the inner diameter of the thread grooves of the first and second female threaded areas 15, 16. The non-threaded area 17 defines a space that is essentially an enlarged diameter of the first and second female threaded areas 15, 16.

[0037] Furthermore, a guide groove 18 is formed on the inner surface of the inner hole 11a. This groove opens toward the end surface on the proximal end Da side of the nail body 10 and extends radially outwardly through the first female threaded region 15, the second female threaded region 16, and the non-threaded region 17 in the direction of the proximal end axis O1. The groove extends radially outward and toward the distal end Db relative to the first female threaded region 15. The first female threaded region 15 and the second female threaded region 16 are separated at a single circumferential location by the guide groove 18.

[0038] (Restricted Body) The restrictor 20 is formed of a metal material such as titanium, and as shown in Figures 4A and 4B , comprises a restrictor body 21 that contacts the bone-joining shaft member 2 when the bone-joining instrument 100 is in use, and a screw portion 22 that rotates relative to the restrictor body 21. The restrictor 20 is inserted into the inner hole 11a of the proximal portion 11 of the nail body 10 through the upper opening 10x (see Figure 2 ).

[0039] The restrictor body 21 has a cylindrical shape centered on the restrictor body axis (third axis) O3 extending in the longitudinal direction D when the bone joining instrument 100 is in use. The restrictor body 21 has an outer diameter that tapers downward toward the front end. Furthermore, when the bone joining instrument 100 is in use, a pair of inclined flat surfaces 21a are arranged 180 degrees circumferentially offset from the front end, which serves as the "lower end" of the restrictor body 21, toward the base end, forming a radially outward-facing cutout of the outer circumference.

[0040] A pair of plate-shaped, slightly triangular pressing portions 21b are formed between the inclined planes 21a. The front ends (lower ends) of the pair of pressing plates 21b are positioned to restrict displacement in the direction of the body axis O3. When the bone-joining shaft member 2, described in detail later, is inserted through the shaft member through-hole 10y of the nail body 10 and penetrates the nail body 10, the pair of pressing portions 21b can contact the bone-joining shaft member 2 (see Figure 2).

[0041] Furthermore, a rectangular guide protrusion 21c is formed on the outer circumference of the restrictor body 21, protruding radially outward and extending in the direction of the restrictor body axis O3. When the restrictor body 21 is inserted into the inner hole 11a of the nail body 10, the guide protrusion 21c is disposed within the guide groove 18 of the nail body 10, restricting relative rotation of the nail body 10 while guiding the restrictor body 21 in the longitudinal direction D within the inner hole 11a of the nail body 10 (see FIG. 3(b)).

[0042] Furthermore, the restrictor body 21 is formed with a restrictor through-hole 21x extending through the outer circumference thereof in a direction intersecting the restrictor axis O3. This restrictor through-hole 21x allows the auxiliary shaft member 3 (described in detail later) to pass through when the bone joining device 100 is in use (see FIG2 ). Specifically, when the bone joining device 100 is in use, the restrictor through-hole 21x extends from the outside of the body toward the inside and from the bottom toward the top, coaxially with the auxiliary shaft member through-hole 10z (see FIG3A and FIG3B ) of the nail body 10.

[0043] The screw portion 22 is annular in shape, centered on the restriction body axis O3. The screw portion 22 covers the outer circumference of the restriction body 21 on the proximal end Da side of the restriction body 21, supports the restriction body 21, and is rotatable relative to the restriction body 21 about the restriction body axis O3. Furthermore, a restriction body-side male threaded region 25 is formed on the outer circumference of the screw portion 22, centered on the restriction body axis O3.

[0044] The restricting body-side male threaded region 25 can be locked to both the first and second female threaded regions 15, 16 of the nail body 10 (see Figures 3A and 3B). Furthermore, the extent of the restricting body-side male threaded region 25 in the direction of the restricting body axis O3 is greater than the extent of the proximal end axis O1 of the non-threaded region 17 of the nail body 10. In other words, the restricting body-side male threaded region 25, positioned between the first and second female threaded regions 15, 16, can be locked to both the first and second female threaded regions 15, 16.

[0045] As shown in Figure 5 , a hexagonal hole (or star-shaped hole, etc.) 22x is formed on the inner side of the screw portion 22, in a portion of the straight annular surface 22b on the restricting body side (described later). By engaging a tool (not shown) with this hole 22x, the screw portion 22 can be rotated about the restricting body axis O3. Next, the restricting body-side male threaded region 25 of the screw portion 22 is locked with the first female threaded region 15 from the second female threaded region 16 (see Figures 3A and 3B ), and the screw portion 22 is inserted into the inner hole 11a of the nail body 10. Once this is done, the guide protrusion 21c of the restricting body 21 is guided by the guide groove 18 (see Figure 3(b)), allowing the screw portion 22 to rotate relative to the restricting body 21 about the restricting body axis O3. Simultaneously, the relative rotation of the restricting body 21 with the nail body 10 is restricted, allowing the restricting body 21 to be inserted into the nail body 10.

[0046] Then, when the male threaded area 25 of the restricting body on the screw portion 22 is locked only with the first female threaded area 15, the pressing portion 21b of the restricting body body 21 contacts the bone-engaging shaft member 2, pressing the bone-engaging shaft member 2 toward the distal end Db in the direction of the restricting body axis O3. This position, where the pressing portion 21b presses the restricting body 20 on the bone-engaging shaft member 2, becomes the "restricting position." When the restricting body 20 is positioned in this restricting position, the relative movement and rotation of the bone-engaging shaft member 2 with respect to the nail body 10 are restricted. Furthermore, when the restricting body 20 is positioned in the restricting position, the restricting body axis O3 becomes coaxial with the proximal end axis O1 (see Figures 3A and 3B).

[0047] As shown in Figure 5, the inner circumference of the screw portion 22 comprises: a restricting body-side tapered annular surface 22a, the inner diameter of which gradually decreases from one side (the base end Da side in the restricted position) toward the other side (the tip end Db side in the restricted position) in the direction of the restricting body axis O3, and is centered on the restricting body axis O3; and a restricting body-side straight annular surface 22b, which is connected to the other side of the restricting body-side tapered annular surface 22a in the direction of the restricting body axis O3 and forms a true circular ring centered on the restricting body axis O3. Furthermore, the screw portion 22 has a flat restricting body end surface 22c facing one side of the restricting body axis O3.

[0048] (ring body) As shown in Figures 6A and 6B, the annular body 30 has a true circular shape centered on the annular body axis (first axis) O4. The annular body 30 is formed from the same material as the restricting body 20. Furthermore, an annular body-side male threaded region 35 is formed on the outer circumference of the annular body 30. This annular body-side male threaded region 35, formed centered on the annular body axis O4, is lockable to the second female threaded region 16 of the nail body 10 (see Figures 3A and 3B). When the annular body-side male threaded region 35 is locked to the second female threaded region 16, the annular body axis O4 and the restricting body axis O3 are aligned (see Figure 5).

[0049] Furthermore, the length of the annular body 30 in the direction of the annular body axis O4 is smaller than the extent of the proximal portion of the non-threaded region 17 in the direction of the axis O1. In this embodiment, for example, the thickness t of the annular body 30 in the direction of the annular body axis O4 is 13 mm, and the extent (length) L of the proximal portion of the non-threaded region 17 in the direction of the axis O1 is 15 mm (see Figures 3A and 3B). Furthermore, the maximum outer diameter of the annular body-side male threaded region 35, i.e., the outer diameter of the thread ridge, is smaller than the inner diameter of the non-threaded region 17. This allows the annular body 30 to be accommodated within the non-threaded region 17.

[0050] Here, the annular body 30 is inserted into the nail body 10 after the restricting body 20 so that it can be accommodated within the non-threaded region 17 after the restricting body 20 is already positioned in the restricted position (see FIG2 ). When the position where the annular body 30 is positioned within the non-threaded region 17 is defined as the "use position," the annular body 30 is positioned in this use position when the bone joining device 100 is in use.

[0051] Returning to Figure 5 , the inner circumference of the annular body 30 comprises: an annular body-side tapered annular surface 30a, whose inner diameter gradually decreases from one side (the base end Da side in the use position) toward the other side (the tip end Db side in the use position) in the direction of the annular body axis O4, and is centered on the annular body axis O4; an annular body-side straight annular surface 30b, which is connected to the other side of the annular body axis O4 relative to the annular body-side tapered annular surface 30a and forms a true circular ring centered on the annular body axis O4. Furthermore, the annular body 30 has a flat annular end surface 30c facing the other side of the annular body axis O4.

[0052] When the annular body axis O4 and the restricting body axis O3 are coaxially arranged, the annular body end surface 30c of the annular body 30 in the use position faces the restricting body end surface 22c of the restricting body 20 in the restricting position in the longitudinal direction D. Furthermore, when the annular body axis O4 and the restricting body axis O3 are coaxially arranged, the entire area of ​​the restricting body end surface 22c faces and contacts a partial area of ​​the annular body end surface 30c in the longitudinal direction D. More specifically, in this embodiment, the restricting body-side tapered annular surface 22a, which constitutes the "inner circumference of the restricting body end surface 22c," is located radially outward of the annular body-side straight annular surface 30b, which constitutes the "inner circumference of the annular body end surface 30c." In other words, the inner diameter of the inner hole of the annular body end surface 30c (the inner hole of the annular body) is smaller than the inner diameter of the inner hole of the limiting body end surface 22c (the inner hole of the limiting body).

[0053] Furthermore, as shown in Figure 6A , the inner circumferential surface of the annular body 30 is formed with an engaging groove (engaging portion) 30x that opens toward one side in the direction of the annular body axis O4 and is recessed radially outward. Two engaging grooves 30x are formed circumferentially at equal intervals (180 degrees apart). The engaging protrusions Kx of the special tool K shown in Figure 7 engage with these engaging grooves 30x. By rotating the special tool K with the engaging protrusions Kx engaged with the engaging grooves 30x, the annular body 30 can be locked into the second female threaded area 16 and simultaneously inserted into the nail body 10, thereby guiding the annular body 30 into the non-threaded area 17 of the nail body 10.

[0054] (End Cap) Returning to Figure 2, the end cap 40 is a member that prevents tissue from flowing into the inner holes 11a and 12a of the nail body 10 (see Figures 3A and 3B). The end cap 40 is inserted into the inner hole 11a of the proximal portion 11 from one side of the proximal portion axis O1 and locks with the second female threaded region 16 of the nail body 10. The end cap 40 comprises a shaft-shaped region 41 that passes through the inner sides of the restricting body 20 and the annular body 30; and a locking region 42 that, when the bone joining device 100 is in use, is located on the proximal end Da side of the nail body 10 relative to the shaft-shaped region 41 and has a male thread 42a formed on its outer circumference.

[0055] When the bone joining instrument 100 is in use, with the male thread 42a engaged with the second female thread region 16 of the nail body 10, the shaft region 41 passes through the inner sides of the restricting body 20 in the restricting position and the annular body 30 in the use position. The shaft region 41 contacts the outer circumference of the auxiliary shaft member 3, which has passed through the auxiliary shaft member through-hole 10z of the nail body 10 and the restricting body through-hole 21x of the restricting body 20, pressing the auxiliary shaft member 3 toward the front end Db of the nail body 10.

[0056] (Shaft member for bone joining) Returning to Figure 1 , the bone-engaging shaft member 2 is disposed within the nail body 10 through the auxiliary shaft member through-hole 10y (see Figures 3A and 3B ) of the nail body 10 when the bone-engaging instrument 100 is in use. The bone-engaging shaft member 2 is positioned toward the bone B1, extending from the outside of the patient's body toward the inside and from the bottom toward the top, through the trochanter B2 of the femur B. Specifically, the bone-engaging shaft member 2 is positioned within the femur B, extending from the outside toward the inside of the patient's body and from the bottom toward the top.

[0057] A male thread 2a is formed on the outer circumference of the distal end of the bone-engaging shaft member 2, designed to lock into the femur B. Furthermore, a pressed groove 2b is formed on the outer circumference of the bone-engaging shaft member 2, extending in the axial direction of the bone-engaging shaft member 2, further toward the proximal end of the male thread 2a. When the bone-engaging instrument 100 is in use, the pair of pressing portions 21b (see Figures 4A and 4B) of the restricting body 20 are aligned in the axial direction of the bone-engaging shaft member 2, and the distal ends of each pressing portion 21b are positioned within the pressed groove 2b. The pair of pressing portions 21b press the bone-engaging shaft member 2 toward the distal end Db of the nail body 10, thereby restricting the relative movement and rotation of the bone-engaging shaft member 2 with respect to the nail body 10.

[0058] (Auxiliary shaft component) When the bone joining device 100 is in use, the auxiliary shaft member 3 is inserted through the auxiliary shaft member through-hole 10z (see Figures 3A and 3B ) of the nail body 10 and is disposed on the nail body 10. When the bone joining device 100 is in use, the auxiliary shaft member 3 is positioned above the bone joining shaft member 2 and parallel to the bone joining shaft member 2. Specifically, the auxiliary shaft member 3 is positioned within the femur B, extending from the trochanter B2 of the femur B toward the bone B1. Male threads 3a are formed on the outer circumference of the front end of the auxiliary shaft member 3, and are designed to lock into the femur B. The front end of the shaft-shaped region 41 (see Figure 2 ) of the end cap 40 contacts the outer circumference of the auxiliary shaft member 3, further toward the base end of the male threads 3a. The shaft-shaped region 41 presses the auxiliary shaft member 3 toward the front end Db of the nail body 10, restricting the relative movement and rotation of the auxiliary shaft member 3 with respect to the nail body 10.

[0059] (Effect) When the bone joining device 100 of this embodiment is used to treat a fracture, an entry hole is first formed at the upper end of the femur B using an awl. The entry hole is then enlarged using a drilling tool such as a drill to form an opening Ba that communicates with the medullary cavity of the femur B. A guide cable (not shown) is then passed through the opening Ba. With the restrictor 20 and annular body 30 already positioned inside the nail body 10, the guide cable is passed through the inside of the nail body 10, the restrictor 20, and the annular body 30, and the nail body 10 is inserted through the opening Ba.

[0060] After this, a perforating tool is used to form a bone hole for the bone-joining shaft member 2 and a bone hole for the auxiliary shaft member 3, and the bone-joining shaft member 2 and the auxiliary shaft member 3 are then locked in place. After this, the restrictor 20 is further locked into the nail body 10, pressing the bone-joining shaft member 2 downward and securing it. Finally, the end cap 40 is locked into the nail body 10, completing the installation of the bone-joining device 100.

[0061] According to the bone joining device 100 of the present embodiment described above, a first female threaded region 15 and a second female threaded region 16 are formed inside the nail body 10 of the intramedullary nail 1, and a non-threaded region 17 without female threads is formed between the first female threaded region 15 and the second female threaded region 16. Therefore, if the restricting member 20 is inserted into the nail body 10 and positioned in the restricting position "engaged only in the first female threaded region 15," and the annular member 30 is engaged with the second female threaded region 16 and inserted inside the nail body 10 so as to be accommodated in the non-threaded region 17, even if the annular member 30 rotates in the non-threaded region 17 due to external factors, the male threaded region 35 on the annular member will not be engaged with the first female threaded region 15 or the second female threaded region 16, and will rotate idly in the non-threaded region 17.

[0062] Therefore, the annular body 30 does not fall off from the nail body 10 and remains in the non-threaded area 17. Therefore, even if the limiting body 20 at the limiting position rotates due to external factors and attempts to move toward the base end Da side in the longitudinal direction D (upward when the bone joining instrument 100 is in use) within the nail body 10, such movement can be restricted by the annular body 30, thereby preventing the limiting body 20 from falling off and preventing the limiting body 20 from moving significantly from the limiting position.

[0063] In particular, in this embodiment, the outer diameter of the thread ridge of the male threaded region 35 on the annular body side is smaller than the inner diameter of the non-threaded region 17. This allows the annular body 30 to smoothly rotate in the non-threaded region 17. Furthermore, in this state, a gap is formed between the annular body 30 and the non-threaded region 17, allowing the annular body 30 to move radially within the non-threaded region 17. As a result, the annular body axis O4 of the annular body 30 is axially offset from the proximal end axis O1, which serves as the center of the first and second female threaded regions 15 and 16. This reliably prevents the annular body 30 from falling out of the non-threaded region 17.

[0064] Furthermore, the inner diameters of the thread ridges of the first and second female threaded regions 15, 16 are smaller than the inner diameter of the non-threaded region 17. Consequently, a step is formed between the first and second female threaded regions 15, 17, and between the second and second female threaded regions 16, 17. The contact of the annular body 30 with the step prevents the annular body 30 from falling off the non-threaded region 17 on either side in the longitudinal direction D.

[0065] Furthermore, the range of the restricting body's male threaded region 25 in the direction of the restricting body axis O3 is larger than the range of the non-threaded region 17 in the direction of the proximal end axis O1. Therefore, when the restricting body 20 is locked into the nail body 10 and the restricting body's male threaded region 25 is moved from a state "engaged only with the second female threaded region 16" to a state "engaged only with the first female threaded region 15" (e.g., a restricted position), the restricting body's male threaded region 25 can be locked to both the second female threaded region 16 and the first female threaded region 15 as it passes through the non-threaded region 17. This allows the restricting body's male threaded region 25 to smoothly pass through the non-threaded region 17, making it easy and reliable to position the restricting body 20 at a specific location.

[0066] In addition, since the inner circumference of the annular body 30 has an annular body side tapered annular surface 30a, when the shaft-shaped area 41 of the end cover 40 is inserted into the inner side of the annular body 30, the shaft-shaped area 41 can be guided by the annular body side tapered annular surface 30a, which can facilitate the installation of the end cover 40.

[0067] Furthermore, the tapered annular surface 22a on the restricting body side, which constitutes the "inner circumferential edge of the restricting body end surface 22c," is located radially outward of the straight annular surface 30b on the annular body side, which constitutes the "inner circumferential edge of the annular body end surface 30c." Therefore, when the annular body 30 is viewed from above with the nail body 10 already installed in the femur B, the inner circumferential edge of the restricting body end surface 22c is obscured by the annular body 30. When the shaft-shaped area 41 of the end cap 40 is inserted from the inside of the restricting body 20 toward the inside of the annular body 30, it is smoothly guided without becoming stuck between the annular body 30 and the restricting body 20.

[0068] Incidentally, the intramedullary nail 1 has a restrictor 20 and an annular body 30 disposed inside the nail body 10. The nail is sometimes transported in a state where the restrictor end face 20c contacts the annular body end face 30c, generating internal forces on the restrictor end face 20c and the annular body end face 30c, respectively, thereby securing the restrictor end face 20c and the annular body end face 30c. In this embodiment, since the restrictor end face 22c contacts a portion of the annular body end face 30c, even if the annular body 30 and the restrictor 20 are formed of the same metal material, the effects of adhesion between the annular body 30 and the restrictor 20 can be minimized.

[0069] Therefore, when the bone joining device 100 is used, even if the restricting body 20 and the annular body 30 are adhered to each other, the restricting body 30 can be easily separated from the annular body 20 and the restricting body 20 can be pressed into the restricted position.

[0070] Furthermore, as described above, the contact between the restrictor end surface 22c and the annular end surface 30c prevents interference between the annular body 30 and the restrictor 20. Therefore, the annular body 30 prevents the restrictor 20 from moving further toward the base end Da than the annular body 30, thereby preventing the restrictor 20 from falling off.

[0071] Furthermore, since the annular body 30 can only be rotated by the dedicated tool K, it is possible to prevent a third party from accidentally removing the annular body 30 from the nail body 10.

[0072] Here, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the scope of the present invention. For example, the overall thickness of the annular body 30 in the direction of the annular body axis O4 may be no less than the extent of the proximal portion of the non-threaded region 17 in the direction of the axis O1, as long as at least the extent of the annular body male threaded region 35 in the direction of the annular body axis O4 is smaller than the extent of the proximal portion of the non-threaded region 17 in the direction of the axis O1. In this case, at least the annular body 30 disposed in the non-threaded region 17 will not be locked in the first and second female threaded regions 15, 16, but will rotate idly in the non-threaded region 17, thereby preventing the restrictor 20 from significantly moving relative to the nail body 10.

[0073] In addition, an engaging protrusion may be formed on the annular body 30 instead of the engaging groove 30x. In this case, an engaging groove is formed on the dedicated tool K instead of the engaging protrusion Kx.

[0074] Furthermore, contrary to the above-described case, the entire area of ​​the annular body end surface 30c may face and be in contact with a partial area of ​​the restricting body end surface 22c in the longitudinal direction D. [Industrial Applicability]

[0075] The intramedullary nail and bone joining instrument of the present invention can improve usability.

[0076] 1: Intramedullary nail 2: Axis member for bone joining 3: Auxiliary shaft component 10: Nail body 10x: Upper opening 10y: shaft member through hole 10z: Auxiliary shaft component through hole 11: proximal end 11a: Inner hole 12: distal end 12a: Inner hole 15: First female thread area 16: Second female thread area 17: Non-threaded area 20: Restriction 20c: End face of the limiting body 22a: Conical annular surface limiting the body side 22c: Restriction body end face 25: Limit the area of ​​male thread on the body side 30: Ring body 30a: annular body side conical annular surface 30b: straight circular annular surface on the side of the annular body 30c: end face of annular body 30x: locking groove 35: Annular body side male thread area 100: Bone joint instruments B: Thigh bone B1: Bones B2: trochanter D: longitudinal direction Da: base end Db:frontend K: Special tools Kx: Engagement protrusion O1: Proximal end axis (second axis) O2: distal end axis O3: limiting body axis (third axis) O4: annular body axis (first axis)

Claims

1. An intramedullary nail, inserted into bone during bone joining, which, together with a bone-joining shaft member passing through it, fixes the bone from the inside. The nail comprises a nail body, a limiting body, and an annular body. The nail body is cylindrical and has a shaft member through-hole extending through its outer peripheral surface at a midpoint in the longitudinal direction, allowing the aforementioned bone-joining shaft member to pass through. Furthermore, its inner peripheral surface has: a first female threaded area disposed at the base end relative to the shaft member through-hole in the longitudinal direction; a second female threaded area disposed at the base end relative to the first female threaded area; and a non-threaded area disposed between the first and second female threaded areas in the longitudinal direction. The aforementioned limiting body is cylindrical in shape and has a limiting body-side male thread field on its outer peripheral surface that can be locked to the first female thread field and the second female thread field. In the limiting position where it is locked to the first female thread field, the aforementioned bone-joining shaft member disposed in the through hole of the aforementioned shaft member is pressed toward the aforementioned front end side, thereby limiting the relative movement and relative rotation of the aforementioned bone-joining shaft member to the aforementioned nail body. The aforementioned annular body is formed in a ring shape with a first axis as its center and has an annular body-side male thread field on its outer peripheral surface that can be locked to the aforementioned second female thread field. In the use position, relative to the aforementioned limiting body which becomes the aforementioned limiting position, it is disposed on the aforementioned base end side and at least a portion is disposed in the aforementioned non-threaded field. The aforementioned first female thread field and the aforementioned second female thread field are formed with a second axis extending in the aforementioned longitudinal direction as their center. The formation range of the aforementioned annular body-side male thread field in the direction of the aforementioned first axis is smaller than the formation range of the aforementioned second axis in the aforementioned non-threaded field.

2. The intramedullary nail as described in claim 1, wherein the thickness dimension of the aforementioned annular body in the aforementioned first axial direction is smaller than the forming range of the aforementioned second axial direction in the aforementioned non-threaded area.

3. The intramedullary nail as described in claim 1 or claim 2, wherein the aforementioned non-threaded region forms a circular cross-section centered on the aforementioned second axis, and the outer diameter of the thread ridge in the aforementioned annular body-side male threaded region is smaller than the inner diameter of the aforementioned non-threaded region.

4. The intramedullary nail as described in claim 1 or claim 2, wherein the inner diameter of the thread ridge in the aforementioned first female thread field and the aforementioned second female thread field is smaller than the inner diameter of the aforementioned non-thread field.

5. The intramedullary nail as described in claim 1 or claim 2, wherein the aforementioned limiting body-side male threaded area is formed with a third axis as the center, and the formation range of the aforementioned third axis direction in the aforementioned limiting body-side male threaded area is greater than the formation range of the aforementioned second axis direction in the aforementioned non-threaded area.

6. The intramedullary nail as described in claim 1 or claim 2, wherein the inner peripheral surface of the aforementioned annular body has: a conical annular surface, in the aforementioned position of use, the inner diameter gradually decreases from one side of the aforementioned first axis that becomes the aforementioned base end side toward the other side of the aforementioned first axis, and the aforementioned first axis is the center.

7. The intramedullary nail as described in claim 1 or claim 2, wherein the aforementioned limiting body has a limiting body end face facing the aforementioned base side at the aforementioned limiting position, and the aforementioned annular body has: an annular end face facing the aforementioned front end side at the aforementioned use position, and forming an opposing orientation from the aforementioned base side relative to the aforementioned limiting body end face of the aforementioned limiting body before becoming the aforementioned limiting position.

8. The intramedullary nail as described in claim 7, wherein the aforementioned limiting body is formed into a cylindrical shape centered on a third axis, and with the aforementioned first axis and the aforementioned third axis arranged coaxially, the inner periphery of the end face of the aforementioned limiting body is arranged radially outward compared to the inner periphery of the end face of the aforementioned annular body.

9. The intramedullary nail as described in claim 7, wherein a circular inner hole is formed on the end face of the aforementioned limiting body, and an annular inner hole is formed on the end face of the aforementioned annular body, centered on a third axis extending in the aforementioned longitudinal direction, in the aforementioned limiting body that becomes the aforementioned limiting position. The annular inner hole is formed in a circle centered on the aforementioned first axis and has a smaller diameter than the aforementioned inner hole of the limiting body.

10. The intramedullary nail as described in claim 7, wherein the aforementioned limiting body and the aforementioned annular body are formed of the same metallic material, and the entire area of ​​one of the end faces of the aforementioned limiting body and the end face of the aforementioned annular body is oriented relative to a partial area of ​​the other in the aforementioned longitudinal direction.

11. The intramedullary nail as described in claim 1 or claim 2, wherein a locking portion is formed on the inner circumferential surface of the aforementioned annular body, which is recessed toward the radially outward side or protrudes toward the radially inward side, and the aforementioned annular body can be rotated about the aforementioned first axis by means of the aforementioned tool when the aforementioned locking portion is engaged with the locked portion of the tool.

12. A bone joining device comprising: an intramedullary nail as described in claim 1 or claim 2; and a axial member for bone joining, which can pass through a through hole in the aforementioned axial member of the aforementioned intramedullary nail.

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