System for guiding intervertebral spacer between vertebral bodies

Abstract

Provided is a system that enables, even in a narrow operating field, an easy and accurate installation of an intervertebral spacer at a prescribed position between vertebral bodies by a PLIF procedure.　Included is an intervertebral spacer comprising: a pair of abutment surfaces that abut a vertebral body, the pair of abutment surfaces being connected on the ventral side; and a ventral side surface that is a side surface on the ventral side having a convex shape when seen in plan view. A ventral side groove is formed in the ventral side surface along the curving direction, and an intervertebral spacer engagement part having a radius of curvature that is smaller than the radius of curvature of the ventral side surface is formed on the bottom surface of the ventral side groove. Additionally included is a guide device that guides the intervertebral spacer to a prescribed position between the vertebral body and another vertebral body. The guide device has a guide rail on the distal end side that fits together with the intervertebral spacer engagement part and is provided with a handle part on the proximal end side that is gripped outside the body of the patient by an operator. The radius of curvature of a guide rail engagement part on the distal side of the guide rail when seen in plan view is the same as the radius of curvature of the intervertebral spacer engagement part when seen in plan view.

Description

A system for guiding an interbody spacer between vertebral bodies

[0001] The present invention relates to a system for guiding an interbody spacer between vertebral bodies.

[0002] When inserting and installing an interbody spacer between vertebral bodies, the annulus fibrosus of the intervertebral disc 2 between the vertebral bodies 1 shown in Figure 1 is opened to remove the nucleus pulposus inside, and the interbody spacer is then inserted between the vertebral bodies after this removal. Because the spinal nerve system and blood vessels pass near the intervertebral disc 2, extreme care is required during surgery.

[0003] Because the spine is responsible for supporting the body weight, interbody spacers are required to have high rigidity and cover a wide area between the vertebrae. At the same time, because the surgical field is narrow and the nervous system and blood vessels pass nearby, the skills and surgical system required to place the interbody spacer in the appropriate position while avoiding these obstacles are required.

[0004] Interbody spacers can be roughly divided into two types based on their shape: box-type interbody spacers and boomerang-type interbody spacers. When comparing the rate of bone fusion between the interbody spacer and the vertebral body, boomerang-type interbody spacers are superior to box-type interbody spacers.

[0005] Figure 2(A) is a plan view of the lumbar spine. Above the vertebral body 1, there are the spinous process 3, transverse process 4, vertebral arch 5, and facet joint 6, sandwiched between the spinal canal 7, through which the spinal nerves pass. The main surgical techniques for placing an interbody spacer between vertebral bodies are TLIF (transforaminal interbody fusion) shown in Figure 2(B) and PLIF (posterior lumbar interbody fusion) shown in Figure 2(C). TLIF involves resecting the facet joint 6 on either the left or right side of the vertebra, while PLIF involves resecting the spinous process 3 in the center of the vertebra, and the interbody spacer in each technique is inserted in the direction of the arrow.

[0006] The system according to the invention described in Patent Document 1 is a simple system that can easily and accurately place a boomerang-shaped interbody spacer at a predetermined position between vertebral bodies, even in a narrow surgical field.

[0007] Patent No. 6700511

[0008] Among spinal diseases, such as those of the lumbar spine, PLIF is primarily used for lumbar spinal canal stenosis, while TLIF is primarily used for lumbar foraminal stenosis. Lumbar spinal canal stenosis is a common case, and many doctors who are familiar with spinal surgery are experts in PLIF surgery. These doctors tend to avoid TLIF surgery.

[0009] The system described in Patent Document 1 is based on the TLIF procedure, making it difficult to place a boomerang-shaped interbody spacer at a predetermined position between vertebral bodies using the PLIF procedure. Figure 13 shows a boomerang-shaped interbody spacer being placed between vertebral bodies using the TLIF procedure. A conventional push rod 48 is used to push an interbody spacer 49 engaged with a conventional guide rail engagement portion 47 of a conventional guide rail 46. In this case, the interbody spacer 49 can be easily placed at a predetermined position. Figure 14 shows a state in which a boomerang-shaped interbody spacer is placed between vertebral bodies using the invention described in Patent Document 1 using the PLIF procedure. Because the conventional interbody spacer 49 moves along the guide rail engagement portion 47, the tip of the interbody spacer 49 hits the side wall of the intervertebral spacer, making it impossible to place the interbody spacer 49 at a predetermined position within the intervertebral body.

[0010] The object of the present invention is to provide a simple system that can easily and accurately place an interbody spacer at a predetermined position between vertebral bodies using the PLIF procedure, even in a narrow surgical field.

[0011] The present invention (1) is a system for treating spinal diseases, the system comprising: an interbody spacer that is inserted between vertebral bodies and curved so that the ventral side is convex in plan view, the interbody spacer having a pair of abutment surfaces that abut against each vertebral body, the pair of abutment surfaces connected at the ventral side and having a ventral side that is a lateral surface on the ventral side, a ventral groove formed in the ventral side, and an interbody spacer engagement portion formed on a bottom surface of the ventral groove having a radius of curvature smaller than the radius of curvature of the ventral side; and a guide instrument that guides the interbody spacer to a predetermined position between the vertebral bodies, the guide instrument having a guide rail at its distal end that mates with the interbody spacer engagement portion and a handle at its proximal end that is held by a surgeon outside the patient's body, the guide instrument having a guide rail at its distal end that mates with the interbody spacer engagement portion in plan view that is the same as the radius of curvature of the interbody spacer engagement portion in plan view.

[0012] In the system of present invention (1), the radius of curvature in a planar view of the guide rail engagement portion on the distal side of the guide rail is the same as the radius of curvature in a planar view of the interbody spacer engagement portion, and is smaller than the radius of curvature in a planar view of the ventral surface, so the interbody spacer can move with great maneuverability, and even when using the PLIF surgical procedure, the boomerang-shaped interbody spacer can be easily and accurately placed at the desired position between the vertebral bodies.

[0013] The present invention (2) is a system of the present invention (1) in which the center of curvature of the interbody spacer engagement portion in a planar view is eccentric toward the tip side when the interbody spacer is inserted between the vertebral bodies compared to the center of curvature of the ventral surface in a planar view.

[0014] In the system of present invention (2), the center of curvature of the interbody spacer engagement portion in a planar view is eccentric toward the tip side when inserting the interbody spacer between the vertebral bodies relative to the center of curvature of the ventral surface in a planar view, making it easier to place the boomerang-shaped interbody spacer at a predetermined position between the vertebral bodies during surgery.

[0015] The present invention (3) is the system of the present invention (1) or (2), in which a stopper portion that hooks onto the facet joint is formed on the guide rail of the guide instrument.

[0016] In the system of the present invention (3), the guide rail of the guide instrument is formed with a stopper portion that hooks onto the intervertebral joint. By hooking this stopper onto the intervertebral joint, the guide rail does not protrude ventrally beyond the designated position, allowing for safer surgery.

[0017] The present invention (4) is the interbody spacer of the present invention (2).

[0018] By using the interbody spacer of the present invention (4), the boomerang-shaped interbody spacer can be easily and accurately placed at a predetermined position between the vertebrae using the PLIF procedure, even in a narrow surgical field.

[0019] According to the system of the present invention, the system is simple, so that even in a narrow surgical field, the boomerang-shaped interbody spacer can be easily and accurately placed at a predetermined position between the vertebral bodies using the PLIF procedure.

[0020] 1 shows a lateral view of a spine (lumbar vertebrae). (A) shows a plan view of a spine (lumbar vertebrae), (B) shows the insertion direction for TLIF, and (C) shows the insertion direction for PLIF. This is a schematic diagram of an interbody spacer attached to a guide instrument and being operated. This is an enlarged view of an interbody spacer attached to a guide instrument. This is a perspective view of an interbody spacer according to the present invention. This shows a front view (A), a plan view (B), and a horizontal cross-sectional view (C) of an interbody spacer according to the present invention. This is a schematic diagram comparing a system according to Example 1 according to the present invention (top) with a conventional interbody spacer described in Patent Document 1 (bottom). This is a schematic diagram comparing a system according to Example 1 according to the present invention (top) with a system according to Example 2 (bottom). This is a schematic diagram showing a state in which a first interbody spacer has been inserted in a system according to the present invention. This is a schematic diagram showing a state in which a second interbody spacer has been inserted in a system according to the present invention. 10A and 10B are schematic diagrams showing a system according to a third embodiment of the present invention, in which a stopper is attached to the guide instrument. 10C are schematic diagrams showing a specific example of an engagement state between an interbody spacer of the system according to the present invention and a guide rail engagement portion of the guide instrument. 10D are schematic diagrams showing an interbody spacer being inserted between vertebral bodies using the TLIF procedure in the system described in Patent Document 1. 10E are schematic diagrams showing an interbody spacer being inserted between vertebral bodies using the PLIF procedure in the system described in Patent Document 1.

[0021] An embodiment of the present invention will be described below with reference to the drawings. In the following description, "upper" and "lower" refer to the upper and lower sides of the drawings. This "upper" and "lower" are for convenience only, and the device may be installed upside down or horizontally.

[0022] Figure 3 is a schematic diagram showing the state in which an interbody spacer is attached to and operated on a guide instrument according to the present invention, where (A) shows the state in which the interbody spacer 10 is attached to the guide instrument 30, (B) shows the state in which the interbody spacer 10 has been inserted about halfway toward the predetermined position between the vertebrae, and (C) shows the state in which the interbody spacer 10 has been removed from the guide instrument 30 after being placed at the predetermined position between the vertebrae.

[0023] 3(A), the head 32 of the push rod 31 is raised upward, with the rod portion 33 protruding partway upward beyond the upper end of the handle portion 34. At this time, the push rod release button 35 is in the protruding position, locking the push rod 31 so that it does not move downward. The interbody spacer 10 is placed on the lower end of the push rod tip portion 37, and the grip release button 36 is lowered, so that the tip of the gripping rod (no reference number) installed inside the guide instrument 30 grips the interbody spacer 10.

[0024] Thereafter, interbody spacer 10 is inserted between the vertebrae while being grasped as shown in Figure 3(A), and when grasp release button 36 is pulled upward, the grasping rod (unnumbered) is removed from interbody spacer 10, releasing the grasp. Thereafter, when push rod release button 35 is pressed and head 32 is pushed downward, push rod tip 37 also moves down, pushing the upper end of interbody spacer 10, and interbody spacer 10 is guided by guide rails 38 (not shown in Figure 3) to the state shown in Figure 3(B).

[0025] 3(C) shows the state in which head 32 is pushed up to the upper surface of handle portion 34, and interbody spacer 10 is moved along guide rail engagement portion 39. When handle portion 34 is lifted upward in this state, interbody spacer 10 is disengaged from guide rail engagement portion 39, and only handle portion 34 is removed from the body, and interbody spacer 10 is placed in the specified position between the vertebrae.

[0026] 4 is an enlarged view of the state in which the interbody spacer 10 has been attached to the guide instrument 30, showing the stage shown in FIG. 3(B). There is a push rod tip 37 and a guide rail 38 equipped with a guide rail engaging portion 39 at its tip, and the interbody spacer 10 is grasped by a grasping rod (unnumbered) provided inside the push rod tip 37.

[0027] Figure 5 shows a perspective view of the interbody spacer 10 of the present invention. A ventral groove 15 is formed in the ventral surface 16, and a bottom surface 23 is formed at the bottom of the ventral groove 15. The interbody spacer engagement portion 20 is formed along the bottom surface 23. The side that engages with the guide instrument 30 is the posterior end surface 12, and the distal end surface 11 is formed on the opposite side. The surface that contacts the cranial vertebral body between the vertebrae is the upper surface 13, and the surface that contacts the caudal vertebral body between the vertebrae is the lower surface 14 (see Figure 6). These contact surfaces are engraved with many deep grooves to promote bone fusion. A bone graft portion 19 is opened in the center of the interbody spacer 10 to receive graft bone, hydroxyapatite, or the like.

[0028] 6A, 6B, and 6C show a front view, a plan view, and a horizontal cross-sectional view, respectively, of an interbody spacer according to the present invention, and explanations of portions overlapping with those in Fig. 5 will be omitted. Fig. 6C shows the horizontal cross-sectional view, in which the grasping hole 18 is a hole for engaging with the tip of a grasping rod (unnumbered) of the guide instrument 30.

[0029] 7 is a schematic diagram showing a comparison between the system of Example 1 (top) and the conventional interbody spacer system (bottom) described in Patent Document 1, in which (A) shows the interbody spacer 10 starting to move along the guide rail 38, (B) shows the interbody spacer 10 engaging with the guide rail engaging portion 39 and rotating, and (C) shows the interbody spacer 10 being positioned at a predetermined position between the vertebrae. The radius of curvature of the interbody spacer engaging portion 20 is R １ (D) shows the conventional interbody spacer 24 starting to move along the conventional guide rail 46, (E) shows the conventional interbody spacer 24 engaging with the conventional guide rail engaging portion 47 and rotating, and (F) shows the completed placement at the predetermined position between the vertebrae. The radius of curvature of the engaging portion is R Ｃ The system of Example 1 of the present invention shown in the upper row is more maneuverable than the conventional interbody spacer system shown in the lower row, so the width l from the guide rail is １ , l ２ , l ３ and L １ , L ２ , L ３ The comparison with １ <L １ , l ２ <L ２ , l３ <L ３ Therefore, when the system of Example 1 of the present invention is used, the boomerang-shaped interbody spacer can be easily and accurately inserted into a predetermined position between the vertebral bodies even in the PLIF procedure.

[0030] 8 is a schematic diagram showing a comparison between the system of the first embodiment (upper row) and the system of the second embodiment (lower row) according to the present invention, and (A), (B), and (C) in the upper row are the same as (A), (B), and (C) in the upper row of FIG. １ The vertical position of the center of curvature O of the ventral surface 15 ２ In the system of Example 2 shown in the lower part, the center of curvature O of the interbody spacer engagement portion 20 is at the same position as the vertical position of １ and the center of curvature O of the ventral surface 16 ２ It is not the same core, １ The position of is shifted to the tip side by d. The width from the guide rail is l １ '=l １ , l ２ '<l ２ , l ３ '<l ３ Therefore, compared with the system of Example 1, the system of Example 2 can more easily insert the boomerang-shaped interbody spacer into a predetermined position between the vertebral bodies in the PLIF procedure.

[0031] Figure 9 is a schematic diagram showing the insertion of the first interbody spacer 10 using the system of the present invention, in which the interbody spacers 10 are inserted between the vertebral bodies in the order of (A) to (B), (B) to (C), and (C) to (D), and are then placed in the desired position.

[0032] Figure 10 shows the state in which the second interbody spacer 10 is being placed sequentially, following Figure 9. From this figure, it can be seen that the first and second interbody spacers 10 have been easily and accurately placed at the desired positions between the vertebral bodies using the PLIF procedure.

[0033] FIG. 11 is a schematic diagram of a system according to a third embodiment of the present invention, in which a stopper 41 is attached to a guide instrument 40. (A) shows the state in which a first interbody spacer 10 is being inserted, and (B) shows the state in which a second interbody spacer 10 is being inserted. In (A), the interbody spacer 10 is engaged with the tip of the guide rail 40, and the push rod tip 37 presses the posterior end surface 12 of the interbody spacer 10. A stopper 41 is formed at a predetermined position on the guide rail 40 and is hooked onto the upper surface of the facet joint 6. This stopper 41 prevents the guide rail 40 from protruding beyond the vertebral body 1. (B) shows the state in which a second interbody spacer 10 is being inserted. The guide rail 40 used in (A) has been replaced with a guide rail 42. A stopper 43 is also formed on the guide rail 42, but it is located closer to the tip than the stopper 41. This is to prevent the first interbody spacer 10 from being pressed by mistake.

[0034] 12A and 12B are schematic diagrams showing specific examples of engagement between interbody spacer 10 and guide rail engagement portion 39. In Fig. 12A-1, the cross section of guide rail engagement portion 39 is a convex T-shape, while the cross section of the corresponding interbody spacer engagement portion is a concave T-shape. In Fig. 12A-2, the opposite is true.

[0035] In Figures 12 (B-1) and (B-2), the engagement structure is a dovetail groove, while in Figures 12 (C-1) and (C-2), the engagement structure is a ball and socket. Each of these engagements has its own characteristics, with the T-shape and dovetail groove shapes being advantageous in terms of processing costs and enabling secure retention, while the ball-and-socket shape provides good sliding properties.

[0036] Figure 12 (D) is a variation of Figure 12 (A-1), in which the height of the guide rail engagement portion 39 is extremely small compared to the height of the ventral surface of the interbody spacer, making it possible to more easily and accurately place the interbody spacer 10 in the desired position even in the narrow area between the vertebral bodies.

[0037] The system according to the present invention is a simple system that can easily and accurately place an interbody spacer at a predetermined position between vertebral bodies using the PLIF procedure, even in a narrow surgical field.

[0038] 1: Vertebral body 2: Intervertebral disc 3: Spinal process 4: Transverse process 5: Vertebral arch 6: Facet joint 7: Spinal canal 10: Interbody spacer 11: Distal surface 12: Posterior end surface 13: Superior surface 14: Inferior surface 15: Ventral groove 16: Ventral surface 17: Dorsal surface 18: Gripping hole 19: Bone graft portion 20: Interbody spacer engagement portion 23: Bottom surface 24: Conventional interbody spacer 30: Guide instrument 31: Push rod 32: Head portion 33: Rod portion 34: Handle portion 35: Push rod release button 36: Grip release button 37: Push rod distal end portion 38, 40, 42: Guide rail 39: Guide rail engagement portion 41, 43: Stopper 46: Conventional guide rail 47: Conventional guide rail engagement portion 48: Conventional push rod １ : Center of curvature of interbody spacer engagement part O ２ : Center of ventral curvature R １ : Radius of curvature of interbody spacer engagement part R ２ : Radius of ventral curvature R ｃ : Conventional guide rail engagement part curvature radius

Claims

1. A system for treating a spinal disease, comprising: an interbody spacer for use by being inserted between vertebral bodies, curved so that the ventral side is convex in a planar view, the interbody spacer having a pair of abutment surfaces abutting each of the vertebral bodies, the pair of abutment surfaces being connected on the ventral side and having a ventral side which is a lateral surface on the ventral side, a ventral groove being formed in the ventral side and an interbody spacer engagement portion being formed on a bottom surface of the ventral groove having a radius of curvature smaller than the radius of curvature of the ventral side; and a guide instrument for guiding the interbody spacer to a predetermined position between the vertebral bodies, the guide instrument having a guide rail on a distal end side which fits with the interbody spacer engagement portion and a handle portion on a proximal end side which is held by a surgeon outside the patient's body, the guide instrument having a radius of curvature in a planar view of the guide rail engagement portion on the distal side of the guide rail which is the same as the radius of curvature in a planar view of the interbody spacer engagement portion.

2. The system according to claim 1, wherein the center of curvature of the interbody spacer engagement portion in a planar view is offset toward the tip side when the interbody spacer is inserted between vertebral bodies relative to the center of curvature of the ventral surface in a planar view.

3. The system according to claim 1 or 2, wherein the guide rail of the guide instrument is formed with a stopper portion for hooking onto the intervertebral joint.

4. An interbody spacer according to claim 2.

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