WO2022202137A1

WO2022202137A1 - Support member and bone fixation system

Info

Publication number: WO2022202137A1
Application number: PCT/JP2022/008496
Authority: WO
Inventors: 文也中田; 明大中村; 一弘長井
Original assignee: 京セラ株式会社
Priority date: 2021-03-25
Filing date: 2022-03-01
Publication date: 2022-09-29
Also published as: JPWO2022202137A1

Abstract

In the present invention, inside a housing provided with an opening part capable of accommodating a head of a bone screw, a C ring can be fitted to a groove to support the head part, has an inner diameter that is smaller than the outer diameter of the head part, and is provided with a protrusion protruding outward in the radial direction or a recess recessed inward in the radial direction.

Description

Support member and bone fixation system

The present disclosure relates to a support member that supports an installation member that can be placed in bone, and a bone fixation system that includes the support member.

Spinal implants are known for holding fixation rods that fix multiple vertebrae together. The head portion of such a spinal implant employs a support member for supporting the bone screw. Also described is a bone anchor assembly for stabilizing bone.

A support member according to an aspect of the present disclosure is a support member that supports an installation member that can be installed on a bone, and is an opening that is arranged at one end of the installation member and can accommodate a head portion that has a shape that includes a portion of a spherical surface. The head can be supported by fitting into a groove provided in the circumferential direction near the open end of the inner peripheral surface of the opening of the housing in a housing having a C-ring shape. The inner diameter of the C-ring shape is smaller than the outer diameter of the head, and a protrusion projecting radially outward from the outer peripheral surface and fitted into the hole provided in the groove Alternatively, it has a concave portion which is recessed radially inwardly and which is fitted with a convex portion provided in the groove.

A bone fixation system according to one aspect of the present disclosure includes an locating member that can be placed on a bone, comprising a C-ring-shaped support member and a head having a shape that includes a portion of a spherical surface at one end; the inner diameter of the C-ring shape is smaller than the outer diameter of the head, and the support member has projections projecting radially outward from the outer peripheral surface of the C-ring shape, or the housing includes a radially inwardly recessed recess, and the housing includes a groove circumferentially provided near the open end, the groove fitting into a hole that fits into the protrusion or into the recess. It has a convex part that

1 is a perspective view of a spinal implant according to Embodiment 1 of the present disclosure; FIG. 1 is an exploded perspective view of the spinal implant; FIG. 1 is a front view of the spinal implant; FIG. Fig. 3 is a cross-sectional view of the spinal implant; FIG. 2 is an enlarged view of a portion of the cross-section of the spinal implant; It is a top view of a C-ring. It is a sectional view of the above-mentioned C ring. It is a bottom view of a housing. FIG. 4 is a cross-sectional view of the housing; It is the bottom view which looked at the state which C ring engaged with the housing from the downward direction. FIG. 4 is a top view of a C-ring according to Embodiment 2 of the present disclosure; It is a bottom view of the housing which concerns on the said embodiment.

[Embodiment 1]
An embodiment of the present disclosure will be described in detail below. In this embodiment, a spinal implant 1 will be described as an example of a bone fixation system. The present disclosure is not limited to spinal implants 1 .

FIG. 1 is a perspective view of a spinal implant 1. FIG. As shown in FIG. 1, spinal implant 1 is configured to include bone screw 10 and housing 30 . Hereinafter, the axial direction of the bone screw 10 is the z-direction, the direction in which the tabs of the housing 30 face each other is the x-direction, and the direction perpendicular to x and z is the y-direction. Moreover, in the spinal implant 1, the housing 30 side is also called the upper side, and the bone screw 10 side is also called the lower side.

The spinal implant 1 will be described below with reference to FIGS. 2 to 5. FIG. FIG. 2 is an exploded perspective view of the spinal implant 1. FIG. FIG. 3 is a front view of the spinal implant 1. FIG. FIG. 4 is a cross-sectional view of the spinal implant 1. FIG. FIG. 5 is an enlarged view enlarging a part of the cross section of the spinal implant 1. FIG.

The spinal implant 1 is an instrument used in spinal fusion surgery. Spinal implant 1 includes bone screw 10, C-ring 20, and housing 30, as shown in FIG. In the spinal implant 1 , the head 11 of the bone screw 10 is accommodated in the housing 30 and supported by the C-ring 20 so that the head 11 does not come off from the interior of the housing 30 . Therefore, the C ring 20 can be called a support member. In this embodiment, an example in which the bone screw 10 is included in the spinal implant 1 will be described, but a hook may be used instead of the bone screw. Moreover, any member that is installed in a bone may be used, and is not limited to bone screws and hooks.

The bone screw 10 has a male thread formed on the outer periphery of the body portion, and a head portion 11 formed in a substantially spherical shape. Also, a neck portion 12 having a smaller diameter than the head portion 11 is provided between the head portion 11 and the male screw. The bone screw 10 is installed in the spine by inserting the male threaded portion into the spine in spinal fusion surgery. Therefore, the bone screw 10 can be said to be an installation member that can be installed in a bone.

The C-ring 20 is a C-shaped ring in which a part of the ring shape is missing. Details of the C ring 20 will be described later.

The housing 30 accommodates the head 11 of the bone screw 10. Details of the housing 30 will be described later. In this embodiment, the bone screw 10, C-ring 20, and housing 30 are made of biocompatible metal materials such as pure titanium, titanium alloys, cobalt-chromium alloys, and stainless steel.

FIG. 4 shows a cross section of the spinal implant 1 taken along line III-III shown in FIG. As shown in FIG. 4 , in the spinal implant 1 , the head 11 of the bone screw 10 is housed in a housing 30 and fixed by a C-ring 20 so that the head 11 cannot be detached from the housing 30 . Specifically, the head 11 of the bone screw 10 housed in the housing 30 is supported by the C-ring 20 that is subsequently inserted through the opening 31 of the housing 30 . C-ring 20 is engaged in groove 32 of housing 30 so that C-ring 20 is secured to housing 30 . Since the inner diameter of the C-ring 20 is smaller than the outer diameter of the head 11 of the bone screw 10 , the fixed C-ring 20 prevents the head 11 of the bone screw 10 from being removed from the housing 30 .

FIG. 5 shows an enlarged view of the IV part of FIG. As shown in FIG. 5, the C-ring 20 engages the groove 32 of the housing 30 and supports the head 11 of the bone screw 10 on its inner peripheral surface.

[Details of C ring 20]
Next, the C-ring 20 will be described with reference to FIGS. 6 and 7. FIG. As described above, the C-ring 20 is a member for reducing the risk of the head 11 of the bone screw 10 detaching from the housing 30 . The C-ring 20 engages with a groove 32 provided on the inner peripheral surface of the housing 30 within the housing 30 .

The details of the C-ring 20 are shown in FIGS. FIG. 6 is a top view of the C-ring 20 viewed from above, that is, in the z-direction, and FIG. 7 is a cross-sectional view of the C-ring 20 taken along the line VI--VI shown in FIG.

The C-ring 20, which is a support member, can support the head 11 of the installation member, has a substantially C-shape having an opening 22 that is a part of the ring shape, and is made of an elastic material such as metal. It is configured. It also has a protrusion 21 that protrudes outward in the circumferential direction. More specifically, as shown in FIG. 6, the protrusion 21 passes through the center U of the C-ring 20 and the center of the opening 22 of the C-ring 20 in plan view, that is, when viewed from the +z side. At least part of it is located away from the axis V, which is a straight line. Moreover, the protrusion 21 is not axially symmetrical with respect to the axis V. As shown in FIG.

Further, the protrusion 21 is located at a position where the angle θ between the axis V and a straight line passing through the tip of the protrusion 21 (the central portion of the protrusion 21) and the center U is 1° or more and 45° or less in plan view. are placed in The tip of the protrusion 21 is the farthest position from the center U in the direction of protrusion. As a result, the projecting portion 21 faces the opening portion 22 of the C ring 20 across the center U of the C ring 20, and can be positioned in the thick wall portion 33 of the housing 30, which will be described later.

The protrusion 21 fits into a hole 35 provided in the groove 32 of the housing 30 . Then, an operator in the process of assembling the spinal implant 1 assembles the C-ring 20 so that the protrusion 21 of the C-ring 20 fits into the hole 35 of the housing 30 .

Since the C-ring 20 is made of an elastic material such as metal, the opening 22 allows the C-ring 20 to be compressed to a reduced diameter. In the present embodiment, the C-ring 20 has an unloaded state having an unloaded outer diameter (hereinafter referred to as DO1) and an unloaded inner diameter (hereinafter referred to as DI1) and a compressed outer diameter (hereinafter referred to as DO2). and a compressed inner diameter (hereinafter referred to as DI2).

The unloaded outer diameter (DO1) and the unloaded inner diameter (DI1) represent diameters measured when the C-ring 20 is not subjected to contraction stress or expansion stress. Shrinkage stress is stress that makes the opening portion 22 smaller, and expansion stress is stress that makes the opening portion 22 larger.

Outer diameter under compression (DO2) and inner diameter under compression (DI2) represent diameters measured when C-ring 20 is under contractive stress and opening 22 is closed.

The no-load outer diameter (DO1) is greater than the diameter of the opening 31 of the housing 30 and greater than the diameter of the groove 32. Also, the no-load inner diameter (DI1) is smaller than the maximum diameter of the head 11 .

The compressed outer diameter (DO2) is smaller than the diameter of the opening 31 of the housing 30. In addition, the compressed inner diameter (DI2) is larger than the diameter of the neck portion 12 .

The C-ring 20 deforms due to expansion stress, but its inner diameter can be made larger than the maximum diameter of the head 11 in the state of elastic deformation before reaching plastic deformation.

As shown in FIG. 7, the inner peripheral surface of the C-ring 20 includes an upper inner peripheral surface 23 and a lower inner peripheral surface 24. The upper inner peripheral surface 23 is tapered on the upper side (+z side) of the inner periphery of the C ring 20 such that the inner diameter of the C ring 20 increases in the +z direction. The upper inner peripheral surface 23 supports the head 11 of the bone screw 10 from below (-z side). In order to support the head 11 of the bone screw 10 on the upper inner peripheral surface 23, the inner diameter of the C-ring 20 on the upper inner peripheral surface 23, even at the largest point, is outside the head 11 of the bone screw 10. smaller than diameter. Therefore, after the head 11 of the bone screw 10 is accommodated in the housing 30 , the C-ring 20 is engaged with the groove 32 on the inner peripheral surface of the housing 30 to fix the head 11 of the bone screw 10 from the housing 30 . It is possible to reduce the risk of detachment.

In order to increase the range of motion of the bone screw 10 with respect to the housing 30, the lower inner peripheral surface 24 is formed on the lower side (-z side) of the inner periphery of the C-ring 20 as it progresses in the -z direction. A tapered shape is formed to increase the inner diameter.

The upper inner peripheral surface 23 is formed in a tapered shape with a taper angle matching the spherical shape of the head 11 or in a concave spherical shape matching the spherical shape of the head 11 . In other words, the upper end of the upper inner peripheral surface 23 of the C-ring 20 and the lower end of the lower inner peripheral surface 24 have different inner diameters. Thereby, the range of motion of the bone screw 10 with respect to the housing 30 can be increased while supporting the head 11 on the upper inner peripheral surface 23 . Matching to the spherical shape of the head 11 does not refer to a completely identical shape, but rather to a shape that approximately matches.

Using such a C-ring 20, an operator identifies the upper surface and the lower surface of the C-ring 20, aligns the position of the protrusion 21 with the hole 35 of the housing 30, and assembles it appropriately, so that the spinal implant 1 can be obtained as desired. Functionality and strength can be achieved.

[Details of housing 30]
The housing 30 is formed in a substantially cylindrical shape. A pair of tabs extending in the z-direction on a part of the side wall facing each other and a slit formed between the tabs in which a rod (not shown) is arranged are provided. A female thread is formed on the inner peripheral surface of the tab for screwing a set screw (not shown).

Further, the housing 30 accommodates the head portion 11 of the bone screw 10 therein so that the bone screw 10 can be freely rotated with respect to the housing 30 . Further, the head 11 of the bone screw 10 is pressed downward by receiving the pressing force of a rod that is placed above the head 11 of the bone screw 10 in the housing 30 and is pressed by a set screw that is screwed into the housing 30 . Accordingly, an insert (not shown) may be provided to secure housing 30 and head 11 .

Details of the housing 30 are shown in FIGS. FIG. 8 is a bottom view of the housing 30 viewed from below (-z side). 9 is a cross-sectional view taken along line IX-IX of FIG. 8. FIG.

As shown in FIG. 9, a groove 32 is formed in the inner peripheral surface of the housing 30 in the vicinity of the opening 31 in the circumferential direction. The groove 32 is engageable with the C-ring 20 . Moreover, as shown in FIGS. 8 and 9, the groove 32 is provided with a hole 35 . The hole portion 35 is connected to the groove 32 from the lower surface of the housing 30, and the projection portion 21 of the C-ring 20 described above can be inserted therethrough.

Further, as shown in FIG. 8, the housing 30 includes a thick wall portion 33, which is a thick portion of the side wall formed by the inner surface and the outer surface of the housing 30, and a thin wall portion 34, which is a thin portion. In this embodiment, the thin-walled portions 34 are located at two locations in the direction of the opening of the slit for receiving the rod (not shown), and the thick-walled portions 33 are located in a direction perpendicular to the direction of the opening of the slit. Located in two locations.

FIG. 10 shows a state where the C ring 20 is engaged with the housing 30. FIG. 10 is a bottom view of the state where the C-ring 20 is engaged with the housing 30, viewed from below (-z side). In the spinal implant 1, as shown in FIG. 4, the C-ring 20 is engaged with the groove 32 of the housing 30 after the head 11 of the bone screw 10 is accommodated in the housing 30, but in FIG. , the bone screw 10 is not shown.

As shown in FIG. 10 , when the C-ring 20 is engaged with the housing 30 , the opening 22 of the C-ring 20 is located in the thick wall portion 33 of the housing 30 . Thereby, even if the opening portion 22 is weaker in strength than other portions of the C ring 20, sufficient strength can be maintained. That is, if the opening portion 22 is located in the thin wall portion 34, when an excessive load is applied to the spinal implant 1, there is a risk that the housing 30 will break starting from the thin wall portion 34, which is relatively weak in strength. However, this can be suppressed.

Also, when the C-ring 20 is engaged with the housing 30 , the protrusion 21 of the C-ring 20 is also positioned on the thick wall portion 33 of the housing 30 . As a result, the strength of the portion with which the protrusion 21 abuts can be maintained. That is, if the hole portion 35 corresponding to the projection portion 21 is located in the thin wall portion 34, when an excessive load is applied to the spinal implant 1, the housing 30 starts from the thin wall portion 34, which is relatively weak in strength. may be damaged, but this can be suppressed.

[Assembly method]
A method for assembling the spinal implant 1 will be described. As described above, the unloaded inner diameter (DI1) of the C-ring 20 is smaller than the outer diameter of the head 11 of the bone screw 10, so when the C-ring 20 is first inserted into the housing 30, the head of the bone screw 10 11 cannot be accommodated. An operator in the process of assembling the spinal implant 1 first applies expansion stress to the C-ring 20 to expand the inner diameter, inserts the bone screw 10 through the C-ring 20 from the tip of the head 11 , and aligns the bone screw 10 with the neck 12 . Position the C-ring 20. Then, the head portion 11 of the bone screw 10 is accommodated in the housing 30 . Next, the operator moves the C-ring 20 toward the opening 31 of the housing 30 .

When the C ring 20 is moved to the vicinity of the opening 31 of the housing 30, the operator applies force (contraction stress) to the C ring 20 from the outside to the inside. Since the C ring 20 is literally C-shaped, the outer diameter can be easily reduced by applying force from the outside to the inside. Since the compressed outer diameter (DO2) with the opening portion 22 closed is smaller than the diameter of the opening portion 31 of the housing 30, the operator reduces the outer diameter of the C-ring 20 and replaces the projection portion 21 with the hole portion 35. , and insert the C-ring 20 into the housing 30 .

After inserting the C ring 20 into the housing 30 , the C ring 20 is fixed to the housing 30 by moving it to the position of the groove 32 and engaging it with the groove 32 . Since the protrusion 21 is engaged with the hole 35, rotational movement of the C-ring 20 in the circumferential direction is also restricted.

As a result, the head 11 of the bone screw 10 cannot be separated from the housing 30 and is supported by the C ring 20.

[Embodiment 2]
Other embodiments of the present disclosure are described below. For convenience of description, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

In the above-described embodiment, the C ring 20 is provided with the protrusion 21 and the housing 30 is provided with the hole 35 . Conversely, in this embodiment, the C-ring 20' is provided with the concave portion 26 and the housing 30' is provided with the convex portion 36. As shown in FIG.

Description will be made with reference to FIGS. 11 and 12. FIG. 11 is a top view of the C-ring 20' viewed from above (+z side). FIG. 12 is a bottom view of the housing 30' viewed from below (-z side).

As shown in FIG. 11, a recess 26 is provided in the C-ring 20'. The recess 26 is provided at a position corresponding to the protrusion 21 of the C-ring 20 in the first embodiment. Further, as shown in FIG. 12, a convex portion 36 is provided on the housing 30'. The convex portion 36 is provided at a position corresponding to the hole portion 35 of the housing 30 in the first embodiment.

Therefore, when the C-ring 20' is engaged with the housing 30', the projection 36 fits into the recess 26.

Thus, in the present embodiment, the recesses 26 and the projections 36 can provide the same effects as the protrusions 21 and the holes 35 in the first embodiment.

As described above, the C-ring 20 (20') according to the present disclosure supports the bone screw 10 that can be installed in the bone, and is disposed at one end of the bone screw 10 and has a head portion that includes a portion of a spherical surface. In a housing 30 (30') provided with an opening 31 capable of accommodating 11, a groove 32 provided in the circumferential direction near the open end of the inner peripheral surface of the opening 31 of the housing 30 (30') is fitted. By joining together, the head 11 can be supported. The C-ring 20 has a C-ring shape, the inner diameter of the C-ring 20 is smaller than the outer diameter of the head 11, the outer peripheral surface projects radially outward, and the hole 35 provided in the groove 32 It has a protrusion 21 that fits into the. Alternatively, the C-ring 20 is provided with recesses 26 that are recessed radially inward and that mate with protrusions 36 provided in the grooves 32 .

According to this configuration, the mounting position of the C-ring 20 and the housing 30 is uniquely determined by the projection 21 that fits into the hole 35 of the housing 30 or the recess 26 that fits into the projection 36 of the housing 30'. It is possible to reduce the risk of the C-ring 20 rotating after being attached.

Further, the spinal implant 1 according to the present disclosure includes a bone screw 10 that can be installed in a bone, and has a C-ring-shaped C-ring 20 (20′) and a head 11 that includes a portion of a spherical surface at one end. A housing 30 (31') having an opening 31 capable of accommodating the head 11 is included, the inner diameter of the C-ring 20 (20') is smaller than the outer diameter of the head 11, and the C-ring 20 (20') is The outer peripheral surface is provided with a protrusion 21 projecting radially outward or a recess 26 recessed radially inward, and the housing 30 (30') is provided with a groove 32 provided in the circumferential direction near the open end. , the groove 32 has a hole 35 that fits into the protrusion 21 or a protrusion 36 that fits into the recess 26 .

The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments is also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

1 Spinal implant (bone fixation system)
10 bone screw (installation member)
11 head 12 neck 20 C ring (supporting member)
21 Projection 22 Opening 23 Upper inner peripheral surface 24 Lower inner peripheral surface 26 Recess 30 Housing 31 Opening 32 Groove 33 Thick wall 34 Thin wall 35 Hole 36 Protrusion

Claims

By fitting into a groove provided in the circumferential direction in a housing having an opening capable of accommodating a head having a shape including a part of a sphere arranged at one end of an installation member that can be installed on a bone, the above-mentioned capable of supporting the head;
C-ring shape,
The inner diameter of the C-ring shape is smaller than the outer diameter of the head,
on the outer circumference,
a protrusion that protrudes radially outward and fits into a hole provided in the groove; or
A support member comprising a radially inwardly recessed recess that mates with a protrusion provided in the groove.
The support member according to claim 1, wherein the groove is arranged near the opening end of the inner peripheral surface of the opening of the housing.
At least a part of the protrusion or the recess is arranged at a position away from an axis that is a straight line passing through the center of the C-ring shape and the center of the opening of the C-ring shape in a plan view, and is aligned with the axis. 3. A support member according to claim 1 or 2, which is not axially symmetrical with respect to.
4. The support member according to claim 3, wherein, in a plan view, an angle between the axis and a straight line passing through the central portion of the protrusion or the recess and the center of the C-ring shape is 1° or more and 45° or less. .
The housing includes a thick-walled portion having a thick wall formed by the opening and the outer surface of the housing, and a thin-walled portion;
5. The C-ring-shaped opening portion is located in the thick wall portion when the protrusion is fitted in the hole or when the recess is fitted in the projection. 2. The support member according to claim 1.
6. The support member according to claim 5, wherein the projection or the recess is positioned in the thick wall portion when the projection fits into the hole or when the recess fits into the projection. .
The support member according to any one of claims 1 to 6, wherein the inner diameters of the surface of the C-ring-shaped head supporting the head and the surface opposite to the head are different.
The support member according to any one of claims 1 to 7, wherein the mounting member comprises a neck portion having a smaller diameter than the head portion, and the inner diameter of the C-ring shape is larger than the neck portion.
The support member according to claim 8, wherein the inner diameter when the C-ring-shaped opening is closed is larger than the neck portion.
The support member according to any one of claims 1 to 9, wherein the outer diameter of the C-ring shape is larger than the diameter of the groove when not subjected to contractive and expansive stress.
The support member according to any one of claims 1 to 10, wherein the outer diameter of the C-ring shape is larger than the diameter of the opening of the housing when not subjected to contraction stress and expansion stress.
The C-ring-shaped opening can be closed by contraction stress, and the outer diameter when the C-ring-shaped opening is closed is smaller than the diameter of the opening of the housing. 12. A support member according to any one of Claims 11 to 12.
The support member according to any one of claims 1 to 12, wherein the inner diameter of the C-ring shape can be deformed to be larger than the maximum diameter of the head in a state of elastic deformation due to the load of expansion stress.
a C-ring shaped support member;
an locating member capable of being placed on a bone, the locating member having a head shaped to include a portion of a spherical surface at one end;
including a housing with an opening capable of accommodating the head;
The inner diameter of the C-ring shape is smaller than the outer diameter of the head,
The support member has a protrusion protruding radially outward or a recess recessed radially inward on the C-ring-shaped outer peripheral surface,
The bone fixation system, wherein the housing comprises a circumferential groove, the groove comprising a hole that fits into the protrusion or a protrusion that fits into the recess.
the installation member is a bone screw or hook;
15. The bone fixation system of claim 14.
said bone screw or said hook is for a spinal implant,
16. The bone fixation system of claim 15.