Spinal surgery dilator

Abstract

A dilator for percutaneous spinal surgery, comprising an elongated main dilator body and an elongated nerve shield for protecting a nerve root, the main dilator body and the nerve shield each having a complementary contact surface, the main dilator body and the nerve shield defining a cross-section of the dilator, the main dilator body and the nerve shield being slidable relative to one another along an axial direction of the dilator, the dilator having a through hole for receiving a guide rod, the through hole being eccentrically disposed relative to the overall cross-section of the main dilator body and the nerve shield.

Description

[Technical field]

[0001] The present invention relates to a dilator device for percutaneous spinal surgery via a transforaminal approach, and more particularly to a dilator with a shield for protecting the nerve roots coming from the spinal cord. The present invention is particularly applicable to percutaneous surgery such as intervertebral disc fixation by utilizing a space called Kambin's triangle located in the neural foramen to access the intervertebral disc, but is not necessarily limited to said use. The dilator of the present invention creates a space in Kambin's triangle while protecting the exit nerve roots. [Background technology]

[0002] Kambin's triangle is an anatomical passageway located in the neural foramina that may be used to access important structures in various spinal surgeries. Kambin's triangle is known as a safe space to perform percutaneous surgery because it is a clean access route to the intervertebral disc. It is considered safe due to the lack of important vascular and neural elements. However, it is problematic in several respects due to limited space (8-10 mm) and is restricted on one side by the nerve root. Therefore, in endoscopic and percutaneous surgery, there is a risk of nerve root damage due to unintentional incision during open joint surgery to widen the space or pressure on the nerve by endoscopic devices (e.g. cannula), resulting in paresthesia and nerve inflammation. For this reason, available surgeries that can be performed through the neural foramina approach are limited.

[0003] EP 2911733 A1 discloses a dilator unit with a nerve shield. The purpose of the shield is to protect the nerve root during percutaneous surgery using the neural foramen as the access route. The unit comprises an elongated dilator shaft and a shield. The cross sections of the shaft and the shield complement each other and form a circle. The elongated dilator shaft serves to place the shield in place. In use, the unit is placed in the required position in the disc space and rotated until the outer surface of the shield is adjacent to the nerve root. At this point, the dilator shaft is withdrawn and the shield can be left in place. The objective pursued in this document is to be able to place a box or cage in the intervertebral space to prevent damage to the nerve root.

[0004] The dilator unit of EP 2911733 has a circular cross section formed by the dilator shaft and the shield in contact with each other. The unit has an opening in the middle of the cross section corresponding to a passage for receiving a guidewire or thread. The dilator shaft and the shield are in contact along two mutually perpendicular planes. The shield has a recess in each of these perpendicular planes. A corresponding projection of the dilator shaft is located in said recess. The arrangement of the perpendicular planes and the resulting perpendicular arrangement of the recesses allows the shaft and the shield to slide along the longitudinal or axial axis of the unit, but prevents movement in other directions, interlocking both elements. The outer surface of the shield occupies about 200 degrees of the 360 ​​degrees of the circumference of the unit.

[0005] The problem with this device of EP 2911733 is that it significantly reduces the space after the shield is placed, so that there is not enough space left to maneuver afterwards. This reduction in space still limits the possibilities, in particular the introduction of an intervertebral box or cage is not feasible. In fact, the inventor is not aware of this device being commercialized. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent Application Publication No. 2911733 Summary of the Invention

[0007] The object of the present invention is to disclose a set of means by which tissues of Cambin's triangle can be expanded during percutaneous spinal surgery via a transforaminal approach with placement of a nerve shield for nerve root protection without the drawbacks of the prior art.

[0008] In particular, the present invention discloses a percutaneous spinal surgery dilator, preferably for creating a space in Kambin's triangle in percutaneous spinal surgery via a transforaminal approach, comprising an elongated main dilator body and an elongated shield for protecting nerve roots, the main dilator body and the shield each having a complementary contact surface, the main body and the shield defining a circumferential surface of the dilator, the main body and the shield defining a cross-section of the dilator, the body and the shield being capable of sliding relative to one another along an axial direction of the dilator, the dilator also comprising a through hole for receiving a guide wire, the through hole being eccentrically disposed with respect to the combined cross-section of the body and the shield.

[0009] The eccentric location of the hole allows the guide cable housed in the hole to be used to perform bone cutting operations after removal of the body without displacing or applying pressure to the shield which could damage the nerve root.Preferably, the hole is eccentrically located relative to the cross section of the body.

[0010] The present invention also discloses a dilator for percutaneous spinal surgery, preferably for forming a space in Kambin's triangle in percutaneous spinal surgery by a transforaminal approach, comprising an elongated main dilator body and an elongated shield for protecting nerve roots, the main dilator body and the shield each having a complementary contact surface, the main body and the shield defining a circumferential surface of the dilator, the main body and the shield defining a transverse cross-section of the dilator, the body and the shield being slidable relative to one another along an axial direction of the dilator, the dilator having a through hole for receiving a guide rod, the transverse cross-section of the dilator being rectangular or elongated in shape, and the shield being disposed on one of the elongated surfaces of the transverse cross-section.

[0011] The elongated shape combined with the eccentric placement of the holes allows for a shield that protects more space and does not get over-inserted into the cambin triangle, subsequently reducing the available space.

[0012] The present invention also discloses a dilator for percutaneous spinal surgery, preferably for forming a space in Kambin's triangle in percutaneous spinal surgery by a transforaminal approach, comprising an elongated main dilator body and an elongated shield for protecting nerve roots, the main dilator body and the shield each having a complementary contact surface, the main body and the shield defining a circumferential surface of the dilator, the main body and the shield defining a transverse cross section of the dilator, the body and the shield being slidable relative to one another along an axial direction of the dilator, the dilator also comprising a through hole for receiving a guide rod, and the shield having a layered or curved layered shape.

[0013] The layered configuration ensures that no shielding elements encroach on the available operating space.

[0014] These features (eccentricity of the guide hole, rectangular shape of the dilator, and lamellar shape of the shield) can be implemented individually on the dilator, combined in pairs, or all three combined.

[0015] Preferably, the body is elongated in cross section and the shield is disposed on one of the elongated sides of the cross section. Also, preferably, the body has a dimension equal to or greater than the shield along the major axis of the elongated or rectangular section of the dilator, more preferably the major axis is the larger axis of the elongated or rectangular section. Even more preferably, the body has a dimension greater than the shield along the two major axes of the elongated or rectangular section of the dilator, said major axes being perpendicular to each other. This allows the nerve shield to take up less space, which subsequently reduces the available space.

[0016] According to the present invention, the body and the shield do not need to be connected to each other in an axial direction, and it is preferable that the shield does not have a recess for connecting with the body. This results in a slimmer shield and occupies less space. Furthermore, it is preferable that the shield does not have a protrusion for connecting. If it is decided to form a recess or a protrusion for connecting the body and the shield, it is preferable that the recess and the protrusion are formed at both ends of the cross section of the shield, leaving the central part free, so as to minimize the effect on the thickness of the shield (which is preferably minimized). Preferably, the body is of one piece in cross section and does not have parts that can slide relative to each other along the longitudinal direction of the dilator.

[0017] According to the invention, both the shield and the body may have retaining means for limiting (but not preventing) radial movement between the shield and the body, said retaining means being arranged at both ends of the cross section of the shield and preferably comprising a shape at both ends, the shape at both ends preferably having a curved shape, in which case the retaining means limits movement by providing an surmountable resistance.

[0018] As is apparent from the above, the present invention discloses a dilator that is advantageous for dilating tissue of Cambin's triangle. To this end, the cross-sectional dimensions of the dilator must be such that it can pass through the Cambin's triangle in humans. To this end, in some embodiments, the cross-sectional dimensions of the dilator are preferably about 9 mm or less on the long axis and 5.5 mm or less along an axis perpendicular to the long axis.

[0019] The present invention also discloses a tool kit for performing spinal surgery, preferably by a transforaminal approach, comprising a dilator according to the present invention. The kit may also include a drill bit, or various drill bits of different diameters. The kit may also include a guide cable (a so-called "K-wire"). The kit may also include known elements of a transforaminal access system, such as a Tom Shidi needle (e.g., with a blunt tip, and / or a cutting tip, and / or a drill), and controls for the various percutaneous components.

[0020] The dilator according to the invention may be used for various percutaneous spinal procedures by transforaminal approach, including vertebral arthrodesis in general, and installation of intervertebral boxes or cages in particular. Preferably, the dilator according to the invention may be used for procedures that involve cutting a portion of bone (typically from the articular process) to access the intervertebral disc space. A typical procedure is to insert a guide cable, insert the dilator along the guide cable, and remove the body of the dilator while leaving the shield behind. In this way, the nerve roots remain protected. The space created by the dilator may then be used to perform additional spinal procedures, such as any of the following groups, or combinations thereof, including cutting of bone using a drill bit, cleaning and preparation of the intervertebral disc space, and placement and installation of an intervertebral box / cage for arthrodesis, preferably sequentially. [Brief description of the drawings]

[0021] For a better understanding, the following drawings are attached, which show, by way of example, illustrative but non-limiting embodiments of the invention.

[0022] [Figure 1] FIG. 1 is a perspective view of an expander. [Diagram 2] 2 shows the expander from a different perspective than FIG. 1. [Diagram 3] 1 is a central cross-section of the expander. [Figure 4] FIG. 13 is another perspective view of the expander with its components separated. [Diagram 5] 13A-13C diagrammatically illustrate how the expander shown in the previous figure can be used to place an intervertebral box or cage. [Figure 6] 13A-13C diagrammatically illustrate how the expander shown in the previous figure can be used to place an intervertebral box or cage. [Figure 7] 13A-13C diagrammatically illustrate how the expander shown in the previous figure can be used to place an intervertebral box or cage. [Figure 8] 13A-13C diagrammatically illustrate how the expander shown in the previous figure can be used to place an intervertebral box or cage. [Figure 9] 13A-13C diagrammatically illustrate how the expander shown in the previous figure can be used to place an intervertebral box or cage. [Figure 10] 13A-13C diagrammatically illustrate how the expander shown in the previous figure can be used to place an intervertebral box or cage. [Figure 11] 13A-13C diagrammatically illustrate how the expander shown in the previous figure can be used to place an intervertebral box or cage. [Figure 12] 1 shows an intervertebral box or cage. [Figure 13] 13 shows a cross section along the bottom of the box of FIG. 12. [Figure 14] Assembly of the parts to form the box and attachment to the cannula are shown. [Figure 15] This shows one of the two parts that form the box. [Figure 16] 12A-12D are schematic diagrams showing the position of the box or cage within the intervertebral space after it has been placed using the procedure shown in FIGS. [Figure 17] FIG. 5 shows a schematic diagram of a commercially available kit or unit including an expander such as those in FIGS. 1-4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] 1 to 4 show an example of an expansion device 1 according to the present invention.

[0024] The dilator 1 is composed of a body 2 and a shield 3, the body 2 and the shield 3 having an elongated shape used in percutaneous surgery, and the body 2 and the shield 3 have a mated shape so that the dilator 1 has a uniform outer surface. More specifically, as shown in FIG. 3, the cross section of the dilator 1 (composed of the cross sections of the body 2 and the shield 3) is elliptical or egg-shaped. The dilator 1 also has a longitudinal through hole 22, the purpose of which is to accommodate a guide (e.g., a K-wire) that guides the trajectory of the dilator 1 inside the patient's body. The hole 22 is located eccentrically with respect to the center of the cross section of the dilator, in particular, the hole 22 formed in the body 2 is located farther from the outer surface of the dilator 1 formed by the shield 3 than the outer surface of the dilator 1 formed by the body. The outer surfaces formed by the body and the shield, respectively, face opposite to each other. This offset of the holes makes it easier to create additional space later by placing a drill bit to cut one or both of the vertebrae.

[0025] The body 2 also has a pointed distal end 21. As shown in Figure 1, the body 2 has a recess for receiving the shield along which the shield may slide. However, it is possible for the body and shield to be non-interlocking, in which case relative radial movement is either fully permitted or not fully prevented.

[0026] The shield 3 has a curved thin plate shape in cross section. The thin plate shape helps to make the shield as thin as possible. More specifically, the shield 3 is formed in cross section by two main surfaces, an outer surface forming part of the outer surface of the dilator 1, another inner surface parallel to it, and two ends forming a connection between both main surfaces. In order to make the shield thinner, both main surfaces are parallel to each other. Moreover, the shield does not have a mounting recess in the main surface, which allows for an even slimmer shield. Moreover, in the illustrated example, the end 39 of the shield 3 is also not provided with a recess for connecting with the body. It is not necessary to connect the body 2 and the shield 3 to prevent movement between them. If considered appropriate, the end 39 can be provided with a connecting protrusion (not shown in the figures) or instead be given a shape that limits but does not prevent radial movement.

[0027] The shield may have a handling shank 31. The shank may take various shapes. In general, the instrument is shown diagrammatically, with the necessary connection and / or handling elements located at its distal and / or proximal ends.

[0028] The box is introduced using percutaneous means, as shown diagrammatically in Figure 2, which shows an endoscopic cannula 6 approaching the intervertebral space in an anterior route.

[0029] Figures 5 to 11 show diagrammatically the procedure for placing the dilator. The method starts with the placement of a guide cable 4 (K-wire) by a transforaminal approach (Figure 5). The guide cable 4 is placed opposite or penetrates the intervertebral disc 1003 located between the vertebrae 1001, 1002. From here, said cable serves as a guide for introducing the dilator so that the corresponding shield 3 faces the nerve root 1004 to be protected, as shown in Figure 6. The body 2 of the dilator is then removed and slid against the shield 3. The shield 3 stays in place and protects the nerve root 1004. As can be seen from Figure 7, the guide cable 4 also stays in place. From the position of Figure 7, the necessary transcutaneous operation can be started by a transforaminal approach. Figures 8 to 11 show the possible operations. To explain the operation, the endoscopic cannula protecting the elements to be inserted according to what is required in each case is not shown. Figure 8 shows how to insert a drill bit 5 to cut a part of the lower vertebra 1002. If necessary, it is also possible to cut a part of the upper vertebra or both vertebrae. The purpose of the cut is to make space for the subsequent operation. To perform the cut, the drill bit must protrude from the surrounding cannula (not shown), so the shield 3 acts as a barrier to prevent cutting and / or compression of the nerve root 1004. Figure 8 shows the cut part 1013. In this case, the cut part corresponds to the upper articular process of the lower vertebra 1002. It should be noted that the fact that the hole of the expander is in an eccentric position with respect to the center of the cross section of the expander makes it possible to cut a part of the vertebra without moving the shield 3 from its position. Moving the shield 3 from its position would put pressure on the nerve root 1004, which would cause paresthesia.

[0030] The drill bit 5 can then be removed and the required operation can be carried out. If a significant amount of bone needs to be removed, two or more drill bits may be inserted in sequence, with the drill bits being of progressively larger diameters.

[0031] It is then possible to introduce tools 6 (clamps and / or cutters, extractors, etc.) to clean the interior of the disc 1003, thus providing a way to place a cage or box 9 for performing an intervertebral fusion. Using this system, different kinds of intervertebral boxes or cages can be introduced percutaneously, intended to be inserted into the intervertebral space to fuse and / or separate two vertebrae.

[0032] Figures 12 to 15 show an example of a box 9 made up of two bodies 92, 93 with mating shapes, each of which is appropriately sized to allow the passage of an endoscope cannula passing through the Kambin triangle, and which is provided with a corresponding hole 971 for a guide cable. The parts are assembled together.

[0033] When the parts are assembled, the guide holes are coaxial, one hole is a through hole and the other hole has threads 922 for receiving an endoscopic guide.

[0034] The assembly can be carried out, for example, by means of a set of respective paired recesses and protrusions located at the contact interface between both parts, said protrusions being preferably perpendicular to the coaxial axis of the holes, said holes being preferably located in each of the paired protrusions.

[0035] The box also includes a connecting element in the form of a screw 971, which is fixed by a screw 981, fixing the parts 92, 93. The screw 981 can be attached to a respective screw of one or both of the parts 92, 93. Each of the two parts 92, 93 has a through hole 921, 931, which has an entrance in the proximal region and an exit at one base, and which receives a means for fixing to the adjacent vertebrae, for example a screw or pin 951, 952 with a sharp protrusion. Each of the sharp pins 951, 952 is arranged on one base of the box, facing in a different direction.

[0036] The method for placing Box 9 is as follows:

[0037] First, part 92 is positioned while being guided by an endoscope guide screwed into the corresponding thread 922 of part 92. Without removing the guide, another part is positioned through the endoscope cannula, also guided by the endoscope guide. This movement holds both parts together and interlocks them by their conjugate shapes.

[0038] Next, pins 951, 952 are inserted and driven into the adjacent vertebrae.

[0039] Finally, the screw 98 is slid along the endoscope guide and then a tool is introduced to screw the screw 98 .

[0040] The threading tool, the unscrewed endoscope guide, the endoscope cannula, and the shield 3 are then removed.

[0041] The placement method may vary from that shown, different percutaneous and non-percutaneous techniques may be used, and the sequence of procedures may be altered. The introduction route is through Kambin's triangle, but is made safe with the use of a shield to protect the nerve roots, which is best placed using a dilator as described above.

[0042] Figure 16 shows how the box 9 is placed. Typically, a foraminal approach is used to introduce the box 9, so the box 9 is placed at an angle. However, in intervertebral fusion surgery, two boxes 9 are usually placed, one through the left neural foramen and one through the right neural foramen.

[0043] FIG. 17 shows an example of a commercial kit for performing percutaneous surgery, including a dilator 1 according to the present invention, a guide cable 4, and at least one drill bit 5 or a set of drill bits of different sizes. The kit may also include known elements of a transforaminal access system, such as Tom Shidi needles 11 (e.g., blunt tips and / or cutting tips and / or drills, as well as controls 12 for the various elements). In general, heads for connecting to the controls for the various elements are not shown, so as not to overwhelm the illustration. Also not shown is the use of various endoscopic cannulas, which may be used as needed and according to the specialist's judgment.

[0044] The dimensions of the illustrated dilator may vary depending on the type of vertebra to which it is directed. In this example, the cross section of the dilator is approximately 9 mm on the long axis and 5.5 mm along an axis perpendicular to the long axis. The shield, for example, has a constant thickness of 0.75 mm and a longitudinal length of 8 mm.

[0045] The through hole of the dilator is approximately 1.75 mm and is positioned at a distance of at least 2 mm from the shield. The axial length of the dilator is approximately 180 mm and the length of the shield is 170 mm.

[0046] The placement method may vary from that shown, and percutaneous techniques and modifications other than those shown may be used, and the sequence of operations may be altered.

[0047] Although the present invention has been described with reference to preferred embodiments, these should not be construed as limiting the invention, which is defined by the broadest interpretation of the following claims. [Explanation of symbols]

[0048] 1. Expander 2 Main unit 3. Shield 4 Guide Cable 5 Drill bits 6 Endoscope cannulas, tools 9. Box 11 Tomsidian Needle 12 Control 21 Distal end 22 Through hole 31 Shank 39 End 92, 93 Parts, main body 98 Screws 921, 931 Through holes 922 mountain 951, 952 pins 971 holes 1001, 1002 vertebrae 1003 Intervertebral disc 1004 Nerve root 1013 Cutting part

Claims

1. 1. A dilator for percutaneous spinal surgery via a transforaminal approach, comprising an elongated main dilator body and an elongated nerve shield for protecting a nerve root, the main dilator body and the nerve shield each having a complementary contact surface, the main dilator body and the nerve shield defining a cross-section of the dilator, the main dilator body and the nerve shield being slidable relative to one another along an axial direction of the dilator, the dilator comprising a through hole for receiving a guide rod, the through hole being eccentrically disposed with respect to the combined cross-section of the main dilator body and the nerve shield.

2. 10. The dilator of claim 1, wherein the dilator has an oval or elongated cross-section, and the nerve shield is disposed on one of the elongated sides of the cross-section.

3. The expander according to claim 1 or 2, characterized in that the nerve shield has a thin plate-like or curved thin plate-like shape.

4. The dilator of any one of claims 1 to 3, characterized in that the cross-section of the nerve shield has a central region of constant thickness.

5. The dilator of any one of claims 1 to 4, characterized in that the nerve shield does not have a recess for interfacing with the main dilator body.

6. The dilator of any one of claims 1 to 5, wherein the nerve shield does not have any protrusions for interfacing with the main dilator body.

7. The dilator of any one of claims 1 to 6, wherein both the nerve shield and the main dilator body have retention means for limiting relative movement between the main dilator body and the nerve shield, the retention means of the nerve shield being located at both ends of the cross-section of the nerve shield.

8. 8. The dilator of claim 7, wherein the nerve shield retention means comprises end shapes having curved shapes.

9. 9. The dilator of claim 8, wherein the protruding surface has a curved shape.

10. A tool kit for percutaneous spinal surgery by a transforaminal approach, characterized in that it comprises a dilator according to any one of claims 1 to 9.

11. 11. The tool kit of claim 10, also comprising a drill bit.

12. 12. The tool kit of claim 11, also comprising a guide cable.

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