Spine stabilization system

Abstract

To provide a spine stabilization system that improves operability during an operation.SOLUTION: A spine stabilization system 1 is equipped with; a first connector member 11 which is freely detachably connectable to a first rod member extending along a head-tail direction of the spine; and a second connector member 12 which is freely detachably connectable to a second rod member extending along the head-tail direction of the spine and which is integrally connected to the first connector member 11. The first connector member 11 and the second connector member 12 are integrally connected mutually in a relatively freely rotatable manner in a prescribed range around an axial direction that is orthogonally crossing the first and the second rod members. As a result, operability during an operation can be improved.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a spinal stabilization system capable of stabilizing the spine by means of various implants that are attached to each vertebra of the spine. [Background technology]

[0002] Conventionally, surgical treatments (e.g., spinal deformity correction and fixation) have been performed to stabilize the spine by making a large incision in the midline of the patient's back, inserting pedicle screws or rods into the body through the incision and attaching them to the spine to improve the stability of the spine or correct spinal deformity. That is, in this spinal deformity correction and fixation, the spine is stabilized by using an implanted material made of a biocompatible material such as a titanium alloy or a cobalt-chromium alloy, for example, a pedicle screw screwed into each pedicle (each vertebra) along the cephalad direction of the spine, or a rod extending along the cephalad direction of the spine and connected to each pedicle screw. Therefore, a surgical procedure has been adopted in which a new rod is arranged in parallel with the rod using a connector member or the like at the axial end of the rod, thereby enabling the correction force and strength of the two rods to be increased and the fixation range along the cephalad direction of the spine to be increased.

[0003] As an example of a connector member used in this manner, Patent Document 1 describes a connector system including a first attachment portion having a first body portion configured to receive and secure a first spinal rod, the first attachment portion having a longitudinal member extending from the first body portion and terminating at a free end, and a second attachment portion having a second body portion configured to receive and secure a second spinal rod, the second attachment portion having an opening extending laterally therethrough to receive the longitudinal member of the first attachment portion, the longitudinal member of the first attachment portion extending laterally therethrough to receive the longitudinal member of the second attachment portion. and a second mounting portion received through the opening in the first mounting portion, the second mounting portion being capable of translating along the longitudinal member and rotating about the longitudinal member of the first mounting portion, the second mounting portion further including a saddle having an upper surface and a lower surface, the upper surface configured to contact the second spinal rod and the lower surface configured to contact the first longitudinal member of the first mounting portion, the saddle including a first grooved surface on the lower surface, and the longitudinal member including a second grooved surface configured to mate with the first grooved surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7058709 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the connector system described in Patent Document 1, since the second mounting part is connected rotatably around the entire circumference of the longitudinal member of the first mounting part, during the operation, the second mounting part rotates largely around the longitudinal member of the first mounting part against the surgeon's intention and becomes unstable, so that the connecting operation and the like are not performed smoothly, and there is a problem in operability. Moreover, in the connector system described in Patent Document 1, the second mounting part includes a saddle, and the saddle is mounted in the second mounting part from the top or bottom, that is, the saddle is fixed in the second mounting part by press-fitting from the top or bottom. For this reason, when the first mounting part and the second mounting part are restrained at any relative position, the pressing force transmitted from the set screw to the saddle via the first spinal rod needs to be considerably large, and if this force is insufficient, there is a risk that the fixing force at the relative position between the first mounting part and the second mounting part will be insufficient.

[0006] In other words, because the saddle is fixed into the second mounting part by press-fitting from the top or bottom, the pressing force transmitted from the set screw through the first spinal rod to the saddle is not properly transmitted to the longitudinal member of the first mounting part, and there is a risk that the fixing force at the relative position between the first mounting part and the second mounting part will be insufficient, resulting in an inability to stably fix the spine and reduced reliability.

[0007] The present invention has been made in consideration of the above points, and has an object to provide a spinal stabilization system that improves operability during surgery and improves reliability in stabilizing the spinal column. [Means for solving the problem]

[0008] As a means for solving the above problem, the invention of claim 1 is a spinal stabilization system that is attached to each vertebra of the spine to stabilize the spine, comprising a first connector member that can be removably connected to a first rod member extending along the cranial-caudal direction of the spine, and a second connector member that can be removably connected to a second rod member extending along the cranial-caudal direction of the spine and is integrally connected to the first connector member, wherein the first connector member and the second connector member are integrally connected to each other so that they can be freely rotated relative to each other within a predetermined range around an axial direction perpendicular to the first and second rod members. In the invention of claim 1, in particular, the first connector member and the second connector member are connected to each other so as to be freely rotatable relative to each other within a predetermined range around the axial direction perpendicular to the first and second rod members, so that the first connector member and the second connector member do not rotate relative to each other significantly during surgery against the surgeon's intentions, thereby improving operability. The first connector member and the second connector member are set so as to be capable of relative rotation within a range of approximately 60° around an axial direction perpendicular to the first and second rod members.

[0009] The invention of claim 2 is the invention described in claim 1, characterized in that the second connector member has a shaft portion extending in a direction perpendicular to the first and second rod members, the first connector member has an insertion hole through which the shaft portion of the second connector member is inserted, and a shim member is provided between the inner surface of the insertion hole of the first connector member and the outer surface of the shaft portion of the second connector member, the shim member being movable radially along the insertion hole of the first connector member by pressure from the first rod member received in the first connector member. In the invention of claim 2, the shim member is not pressed in and fixed as in the conventional art (Patent Document 1), so that the pressing force applied to the shim member by the first rod member is appropriately transmitted from the shim member to the shaft portion of the second connector member, resulting in a sufficient fixing force in the relative positions of the first connector member and the second connector member.

[0010] The invention of claim 3 is characterized in that, in the invention described in claim 2, the shim member has a support portion arranged at a position facing or abutting the inner surface of the insertion hole. In the invention of claim 3, the support portion restricts the shim member from moving away from the shaft portion of the second connector member in the radial direction of the shaft portion.

[0011] The invention of claim 4 is the invention as defined in claim 2, wherein the shim member is configured to be able to be assembled in the insertion hole of the first connector member from the axial direction thereof. According to the invention of claim 4, since the shim member can be assembled into the insertion hole of the first connector member from the axial direction thereof, the assembly work can be facilitated.

[0012] The invention of claim 5 is the invention described in claim 2, characterized in that the first connector member has an opening at the bottom of a groove portion that receives the first rod member, which penetrates toward the insertion hole, and a support arc portion provided on the shim member is positioned within the opening. In the invention of claim 5, since the supporting arcuate portion is disposed within the opening, movement of the shim member within the insertion hole of the first connector member in the axial direction of the shaft portion of the second connector member is restricted.

[0013] The invention of claim 6 is characterized in that, in the invention described in claim 2, it is provided with a pin member that regulates the relative movement range along the axial direction of the shaft portion of the second connector member and the relative rotation range around the axial direction with respect to the insertion hole of the first connector member. In the invention of claim 6, the pin member can regulate the relative movement range of the first connector member and the second connector member along the axial direction of the shaft portion and the relative rotation range around the axial direction, thereby simplifying the overall structure. Effect of the Invention

[0014] The spinal stabilization system according to the present invention can improve operability during surgery and improve reliability in stabilizing the spinal column. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a connector member in which a first connector member and a second connector member of a spinal stabilization system according to an embodiment of the present invention are connected together. [Diagram 2] FIG. 2 is a longitudinal cross-sectional view of a connector member including first and second rod members, and in which a first connector member and a second connector member are connected together, of a spinal stabilization system according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a cross-sectional view taken along line AA of FIG. [Figure 4] FIG. 4 is a side view of the connector member in which the first connector member and the second connector member of the spinal stabilization system according to the present embodiment are connected together. [Diagram 5] FIG. 5 is a longitudinal cross-sectional view showing a state in which a shim member is assembled into an insertion hole of a first connector member of the spinal stabilization system according to this embodiment. [Figure 6] FIG. 6 is a longitudinal cross-sectional view showing the state in which the shaft portion of the second connector member is assembled below the shim member in the insertion hole of the first connector member of the spinal stabilization system according to this embodiment. [Figure 7] FIG. 7 is a longitudinal cross-sectional view showing the insertion of a pin member into a pin hole of a first connector member of the spinal stabilization system according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to Figs. The spinal stabilization system 1 according to this embodiment stabilizes an unstable state of spinal alignment. The spinal stabilization system 1 according to this embodiment stabilizes the spinal column by, for example, fixing the spinal column across a plurality of vertebrae along the cranial-caudal direction of the spinal column using various internal implant materials. The internal implant materials include, for example, a plurality of pedicle screws (not shown) screwed into vertebral bodies via the pedicles of each vertebra of the spinal column, first and second rod members 4 and 5 that extend in the cranial-caudal direction of the spinal column and extend in parallel (approximately parallel) to each other, and a connector member 6 that connects the first rod member 4 and the second rod member 5, as shown in FIG. 1 and FIG. 2. The pedicle screws, the first and second rod members 4 and 5, and the connector member 6 are made of the same material, for example, a material with excellent biocompatibility such as a titanium alloy.

[0017] Referring to FIG. 2, the first and second rod members 4, 5 extend in parallel along the cranial-caudal direction of the spine. The first and second rod members 4, 5 have a circular cross section perpendicular to the axial direction. The first and second rod members 4, 5 have the same outer diameter. The outer diameter of the first rod member 4 and the outer diameter of the second rod member 5 may be different. Although not shown, the pedicle screw is selectively fixed to a plurality of vertebrae along the cranial-caudal direction from the rear of the spine. The pedicle screw is screwed into a vertebral body via a pair of left and right pedicles for one vertebra. The pedicle screw is generally also called a pedicle screw. The pedicle screws arranged along the cranial-caudal direction of the spine are connected to each other by the second rod member 5. The pedicle screw includes a rod receiving portion having a groove portion for receiving the second rod member 5, and a screw portion integrally connected to the rod receiving portion and screwed into the vertebral body via the pedicle of the vertebra.

[0018] 1 and 2, the connector member 6 connects the first rod member 4 and the second rod member 5. The connector member 6 is configured by integrally connecting a first connector member 11 and a second connector member 12. The first connector member 11 can be connected to the first rod member 4 in a freely detachable manner. The first connector member 11 is formed in a block shape as a whole. The first connector member 11 has a groove portion 15 for receiving the first rod member 4 and an insertion hole 16 through which a shaft portion 31 of the second connector member 12 described later is inserted. In detail, the first connector member 11 has a pair of arc portions 17, 17 having a U-shaped groove portion 15 with an open upper portion therebetween. The groove portion 15 extends along the axial direction of the first and second rod members 4, 5 when attached to the spinal column. The first rod member 4 is received in the groove portion 15.

[0019] An insertion hole 16 is formed below the groove portion 15. The insertion hole 16 penetrates and extends in a direction perpendicular to the first and second rod members 4 and 5. The direction in which the U-shaped groove portion 15 extends is perpendicular to the direction in which the insertion hole 16 extends. A pin hole 18 is formed at the lower end of the peripheral wall portion around the insertion hole 16 at the middle position in the longitudinal direction, penetrating toward the insertion hole 16. With reference to Figs. 1 and 5, an opening 20 is formed at the bottom of the groove portion 15. A support arc portion 42 of a shim member 40, which will be described later, is inserted into this opening 20. This opening 20 is formed in a rectangular shape in a plan view. This opening 20 penetrates toward the insertion hole 16. With reference to Figs. 1 and 2, first female threaded portions 22, 22 are formed on the inner wall surfaces of the pair of arcuate portions 17, 17, respectively. A first set screw 24 is screwed into this first female threaded portion 22, 22.

[0020] The second connector member 12 can be detachably connected to the second rod member 5. The second connector member 12 is formed in a block shape as a whole. The second connector member 12 includes a groove portion 30 for receiving the second rod member 5, and a shaft portion 31 inserted into the insertion hole 16 of the first connector member 11. More specifically, the second connector member 12 includes a C-shaped groove portion 30 with one side open. The groove portion 30 extends along the axial direction of the first and second rod members 4, 5 in a state where the second connector member 12 is attached to the spinal column. The second rod member 5 is received in the groove portion 30. In the second connector member 12, a shaft portion 31 extends from the lower end of the other side opposite to the open side of the groove portion 30. The shaft portion 31 has a cross section perpendicular to the axial direction formed in a circular shape. The length of the shaft portion 31 is the same as the length of the insertion hole 16 of the first connector member 11.

[0021] 2 and 3, a range-of-motion setting recess 34 is formed on the outer peripheral surface of the lowermost portion of the shaft portion 31 of the second connector member 12, in which the tip of a pin member 50 described later is disposed. The range-of-motion setting recess 34 is formed by recessing the outer peripheral surface of the shaft portion 31 by a predetermined distance L along the longitudinal direction and a predetermined angle α along the circumferential direction. In this embodiment, the range-of-motion setting recess 34 is formed by recessing the distance L along the longitudinal direction by about 2 mm and by a central angle of 30° (total central angle α is about 60°) on one side along the circumferential direction from the lowest end. A second female thread portion 36 is formed on the upper wall portion of the second connector member 12. A second set screw 38 is screwed into this second female thread portion 36. The pin member 50 regulates the relative movement range along the axial direction of the shaft portion 31 of the second connector member 12 with respect to the insertion hole 16 of the first connector member 11, and the rotation range around the axial direction. Specifically, the pin member 50 is inserted into the pin hole 18 provided in the first connector member 11. The tip of the pin member 50 is located within the movable range setting recess 34 provided in the shaft portion 31 of the second connector member 12.

[0022] 2 and 3, a shim member 40 is disposed between an upper inner peripheral surface of the insertion hole 16 of the first connector member 11 and an upper outer peripheral surface of the shaft portion 31 of the second connector member 12. The shim member 40 is formed in a long and narrow plate shape. A support arc portion 42 is provided in the center of the upper surface of the shim member 40 in the longitudinal direction so as to protrude upward. The upper surface of the support arc portion 42 is formed into an arc surface 42A in the cross section (longitudinal cross section along the longitudinal direction of the shim member 40) shown in FIGS. 2 and 5. The curvature of the arc surface 42A of the support arc portion 42 is the same as the curvature of the first rod member 4. The first rod member 4 is supported by the arc surface 42A of the support arc portion 42.

[0023] In the shim member 40, both longitudinal sides of the support arc portion 42 are formed as support portions 44, 44 that restrict upward movement from the insertion hole 16 of the first connector member 11. The lower surface of the shim member 40 is formed as an arc surface 46A in the cross section shown in FIG. 3 (a vertical cross section along the width direction of the shim member 40). This arc surface 46A is formed over the entire longitudinal area of ​​the shim member 40. The curvature of this arc surface 46A is the same as the curvature of the shaft portion 31 of the second connector member 12. The arc surface 46A, which is the lower surface of the shim member 40, is able to abut against the upper outer circumferential surface of the shaft portion 31 of the second connector member 12.

[0024] 5 and 6, when the first connector member 11, the second connector member 12, and the shim member 40 are assembled to form the connector member 6, the shim member 40 is first inserted axially into the insertion hole 16 of the first connector member 11 with its support arc portion 42 facing upward. At this time, the shim member 40 is disposed over the entire axial area of ​​the insertion hole 16. Next, the shim member 40 is pulled upward, and the support arc portion 42 of the shim member 40 is inserted into the opening 20 of the first connector member 11. This restricts the movement of the shim member 40 in the axial direction of the insertion hole 16. At this time, the support portions 44, 44 of the shim member 40 come into contact with the upper inner circumferential surface of the insertion hole 16, respectively.

[0025] 6 and 7, the shaft portion 31 of the second connector member 12 is inserted between the arc surface 46A, which is the lower surface of the shim member 40, and the lower inner circumferential surface of the insertion hole 16 of the first connector member 11. The shaft portion 31 of the second connector member 12 is disposed over the entire axial area of ​​the insertion hole 16 of the first connector member 11. This restricts the movement of the shim member 40 along the up-down direction. Finally, the pin member 50 is inserted and fixed into the pin hole 18 of the first connector member 11, and the tip of the pin member 50 is disposed in the movable range setting recess 34 provided on the lower outer circumferential surface of the shaft portion 31 of the second connector member 12. Then, referring to FIGS. 1, 2, and 4, the first connector member 11 and the second connector member 12 are integrally connected to each other so as to be relatively movable within a range of a predetermined distance L along the axial direction of the shaft portion 31 (in this embodiment, the predetermined distance L is within a range of 2 mm). Moreover, the first connector member 11 and the second connector member 12 are integrally connected to be relatively rotatable around the axial direction of the shaft portion 31 within a range of a predetermined angle α (in this embodiment, the predetermined angle α is within a range of 60°).

[0026] Next, with reference to Figures 1 and 2, an operation method for an operator to connect the first rod member 4 and the second rod member 5 by the connector member 6 during surgery will be described. At that time, each pedicle screw arranged along the cranial-caudal direction of the spine is in a state of being connected to each other by the second rod member 5. Then, first, the second rod member 5 is arranged in the groove portion 30 of the second connector member 12, and the second set screw 38 is screwed (temporarily fastened) into the second female thread portion 36 of the second connector member 12, and the tip surface of the second set screw 38 is brought into contact with the outer circumferential surface of the second rod member 5 for temporary fixation. Next, the axial end of the first rod member 4 is placed in the groove portion 15 of the first connector member 11, and the first set screw 24 is screwed (temporarily fastened) into the first female thread portions 22, 22 provided on the inner peripheral surfaces of the pair of arcuate portions 17, 17 of the first connector member 11, and the tip surface of the first set screw 24 is abutted against the outer peripheral surface of the first rod member 4 to temporarily fix them. At this time, the first connector member 11 and the second connector member 12 are still relatively movable within a predetermined distance L along the axial direction of the shaft portion 31, and are also relatively rotatable around the axial direction of the shaft portion 31 within a predetermined angle α.

[0027] At this time, since the first connector member 11 cannot rotate excessively, i.e., against the surgeon's intention, with respect to the second connector member 12, the axial end of the first rod member 4 can be easily arranged and temporarily fixed in the groove portion 15 of the first connector member 11. Next, after the relative positions of the first connector member 11 and the second connector member 12, i.e., the relative positions of the first connector member 11 and the second connector member 12 along the axial direction of the shaft portion 31 and the relative positions around the axial direction of the shaft portion 31 are respectively determined, the first set screw 24 is finally tightened, whereby the pressing force from the first rod member 4 is transmitted to the shaft portion 31 of the second connector member 12 via the support arc portion 42 of the shim member 40, and the first connector member 11 and the second connector member 12 are restrained at their arbitrary relative positions. Then, the second set screw 38 is finally tightened, whereby the second rod member 5 is firmly fixed in the groove portion 30 of the second connector member 12.

[0028] According to the spinal stabilization system 1 according to the present embodiment described above, the first connector member 11 and the second connector member 12 are integrally connected to each other so as to be rotatable relative to each other within a predetermined range in the axial direction perpendicular to the first and second rod members 4 and 5, i.e., around the axial direction of the shaft portion 31 of the second connector member 12. This prevents the first connector member 11 and the second connector member 12 from rotating excessively relative to each other during surgery, i.e., from rotating significantly relative to each other against the surgeon's intention, thereby improving operability.

[0029] In the spinal column stabilization system 1 according to this embodiment, a shim member 40 is provided between the inner peripheral surface of the insertion hole 16 of the first connector member 11 and the outer peripheral surface of the shaft portion 31 of the second connector member 12, and is movable along the radial direction of the insertion hole 16 of the first connector member 11 by pressure from the first rod member 4 received in the groove portion 15 of the first connector member 11. As a result, the pressure from the first rod member 4 to the shim member 40 by the first set screw 24 in the groove portion 15 of the first connector member 11 is appropriately transmitted from the shim member 40 to the shaft portion 31 of the second connector member 12, so that the fixing force in the relative positions of the first connector member 11 and the second connector member 12 is sufficient.

[0030] Furthermore, in the spinal column stabilization system 1 according to this embodiment, the shim member 40 has support portions 44, 44 that are provided on both longitudinal sides of the support arc portion 42 and are disposed at positions facing or abutting the inner circumferential surface of the insertion hole 16 of the first connector member 11. These support portions 44, 44 restrict the movement of the shim member 40 away from the shaft portion 31 of the second connector member 12 in the radial direction of the shaft portion 31, so that the shim member 40 can be stably held in the insertion hole 16 of the first connector member 11.

[0031] Furthermore, in the spinal column stabilization system 1 according to this embodiment, the shim member 40 can be assembled into the insertion hole 16 of the first connector member 11 from its axial direction, making the assembly work easy.

[0032] Furthermore, in the spinal column stabilization system 1 according to this embodiment, the first connector member 11 has an opening 20 penetrating toward the insertion hole 16 at the bottom of the groove portion 15 that receives the first rod member 4, and the support arc portion 42 provided on the shim member 40 is disposed within the opening 20. This restricts the movement of the shim member 40 along the axial direction of the shaft portion 31 of the second connector member 12, so that the shim member 40 can be stably held within the insertion hole 16 of the first connector member 11.

[0033] Furthermore, the spinal column stabilization system 1 according to this embodiment includes a pin member 50 that restricts the axial movement range and axial rotation range of the shaft portion 31 of the second connector member 12 relative to the insertion hole 16 of the first connector member 11. This makes it possible to simplify the entire structure of the connector member 6 including the first connector member 11 and the second connector member 12.

[0034] In this embodiment, the first rod member 4 is connected to the first connector member 11, and the second rod member 5 is connected to the second connector member 12, but the second rod member 5 may be connected to the first connector member 11, and the first rod member 4 may be connected to the second connector member 12. In this embodiment, the second connector member 12 is provided with a C-shaped groove 30, but a U-shaped groove may be provided similarly to the first connector member 11. [Explanation of symbols]

[0035] 1 spinal stabilization system, 4 first rod member, 5 second rod member, 6 connector member, 11 first connector member, 12 second connector member, 15 groove portion, 16 insertion hole, 20 opening, 31 shaft portion, 40 shim member, 42 support arc portion, 44 support portion, 50 pin member

Claims

1. 1. A spinal stabilization system for attachment to each vertebra of a spinal column to stabilize the spinal column, comprising: a first connector member detachably connectable to a first rod member extending along a cranial-caudal direction of the spinal column; a second connector member that is removably connectable to a second rod member that extends along a cranial-caudal direction of the spine and is integrally connected to the first connector member; A spinal stabilization system characterized in that the first connector member and the second connector member are integrally connected to each other so as to be freely rotatable relative to each other within a predetermined range around an axial direction perpendicular to the first and second rod members.

2. the second connector member has a shaft portion extending in a direction perpendicular to the first and second rod members; the first connector member has an insertion hole through which a shaft portion of the second connector member is inserted, The spinal stabilization system according to claim 1, characterized in that a shim member is provided between an inner surface of the insertion hole of the first connector member and an outer surface of the shaft portion of the second connector member, the shim member being movable radially along the insertion hole of the first connector member by pressure from the first rod member received in the first connector member.

3. The spinal stabilization system according to claim 2 , wherein the shim member has a support portion disposed at a position facing or abutting against an inner peripheral surface of the insertion hole.

4. The spinal stabilization system according to claim 2 , wherein the shim member is configured to be axially mountable within the insertion hole of the first connector member.

5. The spinal stabilization system according to claim 2, characterized in that the first connector member has an opening at the bottom of a groove portion that receives the first rod member, the opening penetrating toward the insertion hole, and a support arc portion provided on the shim member is positioned within the opening.

6. The spinal stabilization system according to claim 2, further comprising a pin member that restricts the relative axial movement range and the relative rotation range around the axial direction of the shaft portion of the second connector member relative to the insertion hole of the first connector member.

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