Spinal fusion kit

Abstract

To provide a spinal fusion kit which is capable of switching between forbiddance and permission of oscillation of an intervertebral implant 100 and even when oscillation of the intervertebral implant 100 is permitted, is capable of preventing release of the intervertebral implant from an insertion instrument.SOLUTION: A spine fusion kit comprises an intervertebral implant 2 and an insertion instrument 3. The insertion instrument 3 includes a rod 4 and a sleeve 5 being slidable in an axial direction of the rod 4. The rod 4 includes holding walls 41 and 42 having a boss 45 engaging a pivot hole 24 of the intervertebral implant 2, and arms 43 and 44 for supporting the holding walls 41 and 42. The sleeve 5 includes a restraint plate 55 interposed between the holding walls 41 and 42, provided at a tip end 52 thereof. The sleeve 5 swings among an oscillation forbiddance position for forbidding oscillation of the intervertebral implant 2, an oscillation permission position for permitting the oscillation of the intervertebral implant 2, and a retreat position where the restraint plate 55 retreats between the arms 43 and 44.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a spinal fusion kit for inserting an intervertebral implant into an intervertebral disc, and to an intervertebral implant suitable for the spinal fusion kit. [Background technology]

[0002] In one spinal fusion procedure, vertebral bodies are joined together with an intervertebral implant inserted into the disc. Some intervertebral implants are inserted into the disc while being pivoted around one end that engages an insertion tool.

[0003] For example, Patent Document 1 describes an intervertebral implant 100 as shown in Fig. 9 and an insertion tool 200 as shown in Fig. 10. The intervertebral implant 100 includes a pointed insertion end 110 and an engagement end 120 that engages with the insertion tool 200.

[0004] The engagement end 120 has a pair of engagement walls 121, 122, and a slot 130 is formed between these engagement walls 121, 122, into which the tip of the insertion instrument 200 is inserted. Each of the engagement walls 121, 122 has a pivot hole 123 formed therein, and a plurality of engagement holes 124 formed around the pivot hole 123.

[0005] On the other hand, the insertion tool 200 includes a tubular body 300 that holds the intervertebral implant 100 in a swingable manner, and a shaft 400 that is inserted into the tubular body 300 and is slidable in the axial direction of the tubular body 300. As shown in Fig. 11 , the tubular body 300 includes a pair of opposing retaining walls 310, 320 that are inserted into the slots 130 of the intervertebral implant 100, and a pair of arms 330, 340 that support the retaining walls 310, 320, respectively. The arms 330, 340 face each other at a distance greater than the distance between the retaining walls 310, 320.

[0006] Each of the retaining walls 310, 320 is provided with a boss 350 that engages with the pivot hole 123. The pair of bosses 350 engage with the pair of pivot holes 123, allowing the intervertebral implant 100 to swing around the pivot hole 123.

[0007] Furthermore, each of the retaining walls 310, 320 is provided with a plurality of protrusions 360 around the boss 350. These protrusions 360 engage with the engagement holes 124, thereby preventing the intervertebral implant 100 from rocking.

[0008] The shaft 400 includes a plate-shaped head 410 interposed between the retaining walls 310, 320. The shaft 400 slides between a locked position, in which the head 410 is interposed between the retaining walls 310, 320, and a pivot position, in which the head 410 retracts between the arms 330, 340. In the pivot position, the arms 330, 340 are flexible so that the retaining walls 310, 320 approach each other. Therefore, when a rotational force is applied to the intervertebral implant 100 with the shaft 400 slid to the pivot position, the arms 330, 340 are flexible until the engagement between the protrusion 360 and the engagement hole 124 is released, causing the intervertebral implant 100 to swing about the pivot hole 123. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Patent No. 10,478,313 Summary of the Invention [Problem to be solved by the invention]

[0010] However, with the above-described intervertebral implant 100 and insertion instrument 200, when the arms 330, 340 are bent so that the engagement between the protrusion 360 and the engagement hole 124 is released at the pivot position, the engagement between the boss 350 and the pivot hole 123 may become insufficient, and the intervertebral implant 100 may be released from the insertion instrument 200.

[0011] In response to this, it is conceivable to omit the protrusion 360 and the engagement hole 124 and press the retaining walls 310, 320 against the engagement walls 121, 122 of the intervertebral implant 100, thereby holding the intervertebral implant 100 by frictional force. However, in this case, there is a risk that the intervertebral implant 100 may rock due to resistance when inserting the intervertebral implant 100 into the intervertebral disc.

[0012] Therefore, an object of the present invention is to provide a spinal fixation kit that can switch between prohibiting and allowing the swinging of the intervertebral implant 100, and that can prevent the intervertebral implant 100 from being released from the insertion tool even when the swinging of the intervertebral implant 100 is allowed, and an intervertebral implant that is suitable for the spinal fixation kit. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides an intervertebral implant including an insertion end and an engagement end, wherein the engagement ends have a pair of engagement walls that face each other and form a slot therebetween, and a pair of pivot holes are provided in each of the pair of engagement walls; an insertion instrument including a rod that swingably holds the intervertebral implant, and a sleeve that is passed through the rod and is slidable in the axial direction of the rod, wherein the rod is inserted into the slot and has a pair of opposing retaining walls, a pair of bosses that are provided on each of the pair of retaining walls and engage with the pair of pivot holes, and a pair of retaining walls that support the pair of retaining walls, The kit for spinal fixation surgery includes a pair of arms facing each other at a distance greater than the distance between the walls, the sleeve having a tip portion inserted into the slot, the tip portion having a restraining plate interposed between the pair of retaining walls, the sleeve sliding between a swing-prohibiting position where the restraining plate is interposed between the pair of retaining walls and prohibits the intervertebral implant from swinging, a swing-permitting position where the tip portion is pulled out a predetermined amount from the slot while the restraining plate remains interposed between the pair of retaining walls and allows the intervertebral implant to swing, and a retracted position where the restraining plate is retracted between the pair of arms.

[0014] According to the above configuration, the intervertebral implant can be prevented from swinging or permitted to swing simply by sliding the sleeve between the swing-preventing position and the swing-permitting position. Moreover, in the swing-preventing position and the swing-permitting position, the restraining plate is interposed between the pair of retaining walls, thereby maintaining engagement between the bosses on the retaining walls and the pivot holes in the intervertebral implant. This prevents the intervertebral implant from being released from the insertion tool. Furthermore, by sliding the sleeve to the retracted position, the arms can bend so that the retaining walls approach each other, allowing the intervertebral implant to be attached to and detached from the insertion tool.

[0015] Each of the pair of engagement walls has an arcuate profile centered on the pivot hole, and at least one of the pair of engagement wallsInner surface a plurality of recesses, which are aligned circumferentially about the pivot hole and open radially from the pivot hole, may be formed on the periphery of the sleeve, and the tip end of the sleeve may be provided with at least one protrusion that fits into one of the recesses in the anti-swing position and that comes out of the one recess in the swing-permitted position. With this configuration, the protrusion provided on the tip end of the sleeve fits into the recess of the intervertebral implant in the anti-swing position, thereby firmly preventing swinging of the intervertebral implant.

[0016] For example, the plurality of recesses may be formed at a pitch of 5 to 30 degrees around the pivot hole.

[0017] The present invention also provides a locking mechanism comprising an insertion end and an engagement end, the engagement end having a pair of engagement walls facing each other and forming a slot therebetween, the pair of engagement walls each having a pair of pivot holes, each of the pair of engagement walls having an arc-shaped profile centered on the pivot hole, and at least one of the pair of engagement walls Inner surface The present invention provides an intervertebral implant having a plurality of recesses formed on the periphery of the implant, the recesses being aligned in the circumferential direction of the pivot hole and opening in the radial direction from the pivot hole as the center. With this configuration, an intervertebral implant suitable for a spinal fixation kit is realized. [Effects of the Invention]

[0018] According to the present invention, it is possible to switch between prohibiting and allowing the rocking of the intervertebral implant 100, and even when rocking of the intervertebral implant 100 is permitted, it is possible to prevent the intervertebral implant from being released from the insertion tool. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view of a spinal fusion kit according to an embodiment of the present invention, showing an intervertebral implant attached to the distal end of an insertion tool. FIG. [Figure 2] FIG. 2 is an enlarged view of a main part of FIG. [Figure 3]1 is a perspective view of an intervertebral implant. [Figure 4] FIG. 1 is a perspective view of the tip of the insertion tool. [Figure 5] FIG. 1 is an exploded perspective view of an insertion tool. [Figure 6] 6 is a cross-sectional view taken along line VI-VI in FIG. 2 when the sleeve is in a swing-preventing position. [Figure 7] FIG. 10 is a cross-sectional view of the sleeve when it is in a swing-permitting position. [Figure 8] FIG. 10 is a cross-sectional view of the sleeve in a retracted position. [Figure 9] 1 is a perspective view of a conventional intervertebral implant. [Figure 10] FIG. 1 is a perspective view of a conventional insertion tool. [Figure 11] FIG. 1 is an exploded perspective view of the tip of a conventional insertion device. DETAILED DESCRIPTION OF THE INVENTION

[0020] 1 shows a spinal fixation kit 1 according to one embodiment of the present invention. This kit 1 includes an intervertebral implant 2 to be inserted into an intervertebral disc, and an insertion instrument 3 to which the intervertebral implant 2 is attached at its tip.

[0021] The intervertebral implant 2 includes a pointed insertion end 2a and an engagement end 2b that engages with the insertion instrument 3. In this embodiment, the intervertebral implant 2 has a curved shape. However, the shape of the intervertebral implant 2 is not limited to this, and it may be straight, similar to the conventional intervertebral implant 100 shown in FIG.

[0022] 2 and 3, the engagement end 2b of the intervertebral implant 2 has a pair of opposing engagement walls 21, 22. A slot 23 is formed between the engagement walls 21, 22. A pair of pivot holes 24 is provided in each of the engagement walls 21, 22. Both pivot holes 24 are aligned coaxially.

[0023] In this embodiment, each of the engagement walls 21 and 22 has an arc-shaped profile centered on the pivot hole 24. Furthermore, in this embodiment, each of the engagement walls 21 and 22 has an arc-shaped profile centered on the pivot hole 24. Inner surface A plurality of recesses 25 are formed on the periphery of the pivot hole 24, aligned in the circumferential direction of the pivot hole 24. These recesses 25 open in the radial direction centered on the pivot hole 24. For example, the recesses 25 are formed around the pivot hole 24 at a pitch of 5 to 30 degrees.

[0024] As shown in FIGS. 4 and 5, the insertion tool 3 includes a rod 4 that holds the intervertebral implant 2 in a swingable manner, and a sleeve 5 that is passed through the rod 4 and is slidable in the axial direction of the rod 4.

[0025] In this embodiment, as shown in FIG. 1, a grip 7 is attached to the end of the rod 4 opposite to the intervertebral implant 2, and an operating section 6 is provided in front of this grip 7. The operating part 6 cannot move relative to the sleeve 5 in the axial direction of the sleeve 5, but can rotate relative to the sleeve 5. The operating part 6 is connected to the grip 7 by a screw structure, and by rotating the operating part 6, the operating part 6 and the sleeve 5 slide in the axial direction of the rod 4.

[0026] The configuration for sliding the sleeve 5 is not limited to this and can be modified as appropriate. For example, the operating unit 6 may be fixed to the sleeve 5, and a spring may be used to bias the operating unit 6 toward the intervertebral implant 2, and the operating unit 6 may be moved closer to the grip 7 against the biasing force of the spring, thereby sliding the sleeve 5.

[0027] 4 and 5, the rod 4 includes a pair of retaining walls 41, 42 that are inserted into the slots 23 of the intervertebral implant 2, and a pair of arms 43, 44 that support the retaining walls 41, 42, respectively. The retaining walls 41, 42 face each other, and the arms 43, 44 face each other at a distance greater than the distance between the retaining walls 41, 42. The retaining walls 41, 42 are each provided with a pair of bosses 45 that engage with the pivot holes 24 of the intervertebral implant 2.

[0028] The sleeve 5 includes a cylindrical main body 51 and a tip portion 52 that protrudes from the main body 51 and has a shape similar to that of a flattened main body 51. The tip portion 52 is the portion that is inserted into the slot 23 of the intervertebral implant 2, similar to the retaining walls 41, 42 of the rod 4.

[0029] In this embodiment, the tip portion 52 is composed of a pair of shoulders 53 located on both sides of the retaining wall 41 and a pair of shoulders 54 located on both sides of the retaining wall 42. In addition, the tip portion 52 is provided with a restraining plate 55 interposed between the retaining walls 41 and 42.

[0030] The restraining plate 55 has a width greater than that of the retaining walls 41, 42, and both ends of the restraining plate 55 are sandwiched between the shoulders 53 and 54. The restraining plate 55 is fixed to the tip portion 52 by a pin 57 (see also Figures 7 and 8) that passes through the shoulder 53, the restraining plate 55, and the shoulder 54. For example, either the restraining plate 55 or the pin 57 is welded to the shoulders 53, 54.

[0031] Both ends of the pin 57 protrude from the shoulders 53, 54 to form protrusions 56. Each protrusion 56 mates with one of the recesses 25 in the intervertebral implant 2.

[0032] The sleeve 5 slides among a swing-prohibited position shown in FIG. 6, a swing-permitted position shown in FIG. 7, and a retracted position shown in FIG.

[0033] The anti-sway position is a position where the restraint plate 55 is interposed between the retaining walls 41 and 42. In addition, in the anti-sway position, each protrusion 56 fits into one of the recesses 25 of the intervertebral implant 2. This prevents the intervertebral implant 2 from swinging.

[0034] The swing-permitted position is a position where the tip 52 is pulled out of the slot 23 by a predetermined amount while the restraint plate 55 remains interposed between the retaining walls 41, 42. Also, in the swing-permitted position, the protrusion 56 comes out of the recess 25, thereby permitting the intervertebral implant 2 to swing.

[0035] The retracted position is a position in which the restraining plate 55 is retracted between the arms 43, 44. This allows the arms 43, 44 to flex so that the retaining walls 41, 42 move closer to each other.

[0036] As described above, in the kit 1 of this embodiment, the rocking of the intervertebral implant 2 can be inhibited or permitted simply by sliding the sleeve 5 between the rocking-preventing position and the rocking-permitting position. Moreover, in the rocking-preventing position and the rocking-permitting position, the restraining plate 55 is interposed between the retaining walls 41, 42, so that the bosses 45 provided on the retaining walls 41, 42 can be maintained engaged with the pivot holes 24 of the intervertebral implant 2. This prevents the intervertebral implant 2 from being released from the insertion instrument 3. Furthermore, by sliding the sleeve 5 to the retracted position, the arms 43, 44 can bend so that the retaining walls 41, 42 approach each other, allowing the intervertebral implant 2 to be attached to and detached from the insertion instrument 3.

[0037] 10 and 11 , the arms 330, 340 bend to release the projection 360 from the engagement hole 124 of the intervertebral implant 100, thereby enabling the intervertebral implant 100 to swing about the pivot hole 123. However, when the intervertebral implant 100 is swung, the swinging motion stops every time the projection 360 engages with the engagement hole 124. Moreover, since the bent arms 330, 340 are pressed against the engagement walls 121, 122 of the intervertebral implant 100 while the intervertebral implant 100 is swinging, the swinging motion of the intervertebral implant 100 is not smooth.

[0038] In contrast, in the insertion instrument 3 included in the kit 1 of this embodiment, the boss 45 is provided on the rod 4, while the protrusion 56 is provided on the sleeve 5 separate from the rod 4, so that the intervertebral implant 2 can be swung smoothly when the sleeve 5 is in the swing-permitted position.

[0039] (Variation) The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0040] For example, the recess 25 may be formed in only one of the engagement walls 21 , 22 of the intervertebral implant 2 , and the tip 52 of the sleeve 5 may be provided with only one protrusion 56 that fits into the recess 25 .

[0041] Alternatively, instead of the recess 25 and the protrusion 56, each of the engagement walls 21, 22 of the intervertebral implant 2 may have a polygonal contour, and one side of the polygon may abut against the tip surface of the main body 51 of the sleeve 5, thereby preventing the intervertebral implant 2 from swinging.

[0042] However, with this configuration, there is a risk that the intervertebral implant 2 may swing when a large rotational force is applied to the intervertebral implant 2 in the swing-preventing position. In contrast, if the protrusion 56 provided on the distal end 52 of the sleeve 5 is configured to fit into the recess 25 of the intervertebral implant 2 in the swing-preventing position as in the above embodiment, it is possible to firmly prevent the intervertebral implant 2 from swinging. With an intervertebral implant 2 including such a recess 25, an intervertebral implant 2 suitable for use in a spinal fixation kit 17 is realized. [Explanation of symbols]

[0043] 1 Spinal Fusion Kit 2 Intervertebral implants 2a Insertion end 2b Engagement end 21, 22 Engagement wall 24 pivot holes 25 depression 3 Insertion equipment 4 rods 41,42 retaining wall 43,44 Arm 45 Boss 5 Sleeve 52 Tip 55 Restraint plate 56 Protrusion

Claims

1. an intervertebral implant including an insertion end and an engagement end, the engagement end having a pair of engagement walls facing each other to form a slot therebetween, the pair of engagement walls each having a pair of pivot holes; an insertion instrument including a rod that swingably holds the intervertebral implant, and a sleeve that is passed through the rod and is slidable in the axial direction of the rod; the rod includes a pair of opposing retaining walls inserted into the slot, a pair of bosses provided on each of the pair of retaining walls and engaging with the pair of pivot holes, and a pair of arms supporting each of the pair of retaining walls and opposing each other at a distance greater than a distance between the pair of retaining walls; the sleeve has a tip end portion that is inserted into the slot, and a restraining plate that is interposed between the pair of retaining walls is provided at the tip end portion; The sleeve slides between a swing-preventing position in which the restraining plate is interposed between the pair of retaining walls and prevents the intervertebral implant from swinging, a swing-permitting position in which the restraining plate remains interposed between the pair of retaining walls and the tip portion is pulled out of the slot by a predetermined amount and allows the intervertebral implant to swing, and a retracted position in which the restraining plate is retracted between the pair of arms.

2. Each of the pair of engagement walls has an arcuate profile centered on the pivot hole, a plurality of recesses, which are aligned in a circumferential direction of the pivot hole and open in a radial direction around the pivot hole, are formed on a peripheral edge of an inner surface of at least one of the pair of engagement walls; 2. The spinal fixation kit according to claim 1, wherein the tip of the sleeve has at least one protrusion that fits into one of the plurality of recesses in the non-swinging position and comes out of the one recess in the swinging-allowed position.

3. 3. The spinal fixation kit according to claim 2, wherein the plurality of recesses are formed at intervals of 5 to 30 degrees around the pivot hole.

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