Electrode probe for radiofrequency ablation

Abstract

A radiofrequency ablation electrode probe includes a shaft extending from a hub and defining at least one lumen. A lead wire is disposed within the lumen, and at least one emitter is coupled to the lead wire. The emitter is coupled to a flexible distal portion of the shaft, such as by a swaging process. The emitter includes a slotted portion defining a slot sized such that swaging the emitter into the flexible distal portion deforms the conductive material. The emitter can include a slotted portion and end portions, and the lead wire can be secured to one of the end portions by a laser welding process. The slots can have a slot pitch within a range of 0.150 to 0.400 millimeters. The slots can be circumferentially arranged with a cut angle within a range of 50 to 90 degrees. A method of manufacturing the electrode probe is also disclosed.

Description

[Technical Field]

[0001] Priority claims This application claims priority to and any benefit of U.S. Provisional Patent Application No. 63 / 424,539, filed November 11, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Ablation systems deliver energy to problematic tissue, heating and destroying its cells. One example is the ablation of nerve tissue to prevent pain signals from being transmitted to the brain. Other examples include the ablation of tumors in the liver, kidney, lung, and bone. When the lesion is intraosseous, e.g., a bone tumor, an introducer assembly can facilitate positioning of the electrode probe to the target location within the bone. In certain instances, it may be desirable for the introducer assembly to provide curved access to difficult anatomical locations. One example includes accessing bone tumors located posteriorly or contralaterally within a vertebral body of the spine, while another example includes accessing the nerve trunk of a vertebral body nerve. Many known electrode probes, especially those with injection or cooling capabilities, are unable to bend sufficiently to follow the curvature of the introducer assembly without impairing their functionality. Furthermore, the complex structure of many known electrode probes results in increased manufacturing and assembly costs and a greater potential risk of component damage. Therefore, there is a need in the art for an electrode probe for an ablation system that overcomes one or more of the aforementioned drawbacks. Summary of the Invention

[0003] The present disclosure is directed to an ablation system and electrode probe for radio frequency (RF) ablation of tissue, and methods of manufacturing the same. The ablation system includes a console, an electrode probe, and optionally an injection module. The console includes an RF energy source and optionally a display that provides a user interface.

[0004] The electrode probe includes a handle or hub and a shaft coupled to and extending from the hub. The hub can include a power coupler configured to be detachably coupled to a power line. The power line can also transmit data between the console and the electrode probe. The hub can include a fluid coupler configured to be placed in fluid communication with the infusion module. The shaft can include a flexible elongate body forming at least a flexible distal portion of the shaft. The shaft can also include a proximal portion, which can be flexible or rigid. A rigid sleeve can coaxially overlie a portion of the elongate body. The elongate body can be made of a polymer, or at least partially formed from a polymer. One or more lumens and / or one or more grooves are provided by extrusion of the elongate body.

[0005] In addition to the flexibility of the elongate body, the emitters are also flexible. The proximal and distal emitters are coupled to a flexible distal portion of the elongate body. The emitters can be secured to the flexible distal portion by a crimping or swaging process. The grooves extend longitudinally along the elongate body and can be positioned diametrically opposite each other around the elongate body. The grooves facilitate improved engagement with the emitters that are swaged onto the elongate body.

[0006] The lumens may be equiangularly arranged or in other suitable configurations. A proximal lead is disposed within the first lumen. The proximal lead is electrically conductive and is secured to the proximal emitter. A distal lead can be disposed within the second lumen and secured to the distal emitter. The proximal and distal leads can be joined to their respective emitters by a welding process, e.g., a laser welding process. A portion of the elongate body forms an insulating spacer between the proximal and distal emitters. The proximal and distal leads extend proximally into the hub. A thermocouple can be disposed within the third lumen. The fourth lumen can be an infusion lumen. An infusion port is defined by the elongate body and configured to be disposed in fluid communication with the fluid coupler on the hub and further in fluid communication with the infusion module when coupled to the fluid coupler. The inlet may be positioned in a portion of the elongate body that forms an insulating spacer between the emitters.

[0007] The emitter includes an inner surface and an outer surface. The emitter is formed with a slot between the inner and outer surfaces. The slot is sized so that the plurality of slots remain sufficiently defined to provide the necessary flexibility despite material deformation caused by crimping or swaging the emitter onto the flexible distal portion of the shaft. The emitter includes a slotted portion and end portions disposed opposite (on both sides of) the slotted portion. One of the leads can be secured to one of the end portions of the emitter.

[0008] The slots can be formed by a laser cutting process or another suitable manufacturing process. Slot parameters can include the kerf, slot pitch, cut angle, and non-cut angle. The kerf (cut width) can be in the range of about 0.015 to 0.035 mm, more specifically about 0.025 mm. The slot pitch can be in the range of about 0.150 to 0.400 mm, more specifically about 0.165 to 0.215 mm, and even more specifically about 0.191 mm. The slot pitch can be regular or irregular. The cut angle can be in the range of about 50 to 100 degrees, more specifically about 62 to 88 degrees, and even more specifically about 82 degrees. The non-cut angle can be in the range of about 10 to 30 degrees, more specifically about 18 to 21 degrees.

[0009] The flexibility of the electrode probe allows it to follow a flexible conduit through a bend of at least 60 degrees, more particularly at least 90 degrees, and even more particularly at least 120 degrees, and / or to be deployed through a bend having a radius of curvature within the range of about 20 to 65 mm, more particularly within the range of about 30 to 55 mm.

[0010] According to a first aspect of the present disclosure, an electrode probe includes a hub, a shaft, and at least one emitter. The shaft extends from the hub and defines at least one lumen. The shaft includes a flexible distal portion. A lead wire is disposed within the lumen and configured to be electrically connected to an RF energy source. The emitter is coupled to the lead wire and is formed from a conductive material. The emitter is swaged onto the flexible distal portion of the shaft. The emitter includes a slotted portion defining a plurality of slots dimensioned such that swaging the emitter onto the flexible distal portion of the shaft deforms the conductive material to reduce the diameter of the emitter.

[0011] According to a second aspect of the present disclosure, an electrode probe includes a hub, a shaft, and at least one emitter. The shaft extends from the hub and defines at least one lumen. The shaft includes a flexible distal portion. A lead wire is disposed within the lumen and configured to be electrically connected to an RF energy source. The emitter is coupled to the lead wire and is formed from a conductive material. The emitter is coupled to the flexible distal portion of the shaft. The emitter includes a slotted portion defining a slot and end portions disposed on opposite sides of the slotted portion. The lead wire is secured to one of the end portions, for example, by laser welding.

[0012] According to a third aspect of the present disclosure, an electrode probe includes a hub, a shaft, and at least one emitter. The shaft extends from the hub and defines at least one lumen. The shaft includes a flexible distal portion. A lead wire is disposed within the lumen and configured to be electrically connected to an RF energy source. The emitter is coupled to the lead wire and is formed from a conductive material. The emitter has a length of at least 8 millimeters and is coupled to the flexible distal portion of the shaft. The emitter includes a slotted portion defining slots. The slotted portion has a slot pitch defined as the distance between longitudinally adjacent slots, the slot pitch being within a range of 0.150 to 0.400 millimeters.

[0013] According to a fourth aspect of the present disclosure, an electrode probe includes a hub, a shaft, and at least one emitter. The shaft extends from the hub and defines at least one lumen. The shaft includes a flexible distal portion. A lead wire is disposed within the lumen and configured to be electrically connected to an RF energy source. The emitter is coupled to the lead wire and is formed from a conductive material. The emitter has a length of at least 8 millimeters and is coupled to the flexible distal portion of the shaft. The emitter includes a slotted portion defining slots disposed circumferentially around an outer surface of the emitter. A cutting angle is defined between opposing ends of each slot, and the cutting angle may be within a range of 50 to 90 degrees. A non-cutting angle is defined between ends of circumferentially adjacent slots. The non-cutting angle may be within a range of 10 to 30 degrees.

[0014] According to a fifth aspect of the present disclosure, an electrode probe includes a hub, a shaft defining at least two lumens, two leads, and two emitters. The first lead is disposed within a first of the lumens and is configured to be electrically connected to an RF energy source. The second lead is disposed within a second of the lumens and is configured to be electrically connected to an RF energy source. The distal emitter is coupled to the first lead and is formed of a conductive material. The proximal emitter is coupled to the second lead and is formed of a conductive material. The proximal and distal emitters are coupled to a flexible distal portion of the shaft. The proximal and distal emitters each include a slotted portion defining a slot. A section of the flexible distal portion between the proximal and distal emitters is an insulating spacer.

[0015] A specific method for manufacturing an electrode probe is disclosed herein. A polymer can be extruded to include an outer surface and at least one of the lumens. The emitter is swaged to the outer surface by a swaging process, which narrows the slot and reduces the diameter of the emitter. In certain implementations, the swaging process further includes swaging the emitter flush downward so that the flexible distal section is at least partially compressed. A lead wire is positioned within the lumen of the flexible distal section and secured in electrical communication with the emitter by a welding process. A shaft is secured to the hub. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view of an ablation system including a console, a channel splitter, an electrode probe for radiofrequency ablation, and an injection module. [Figure 2] FIG. 1 is an elevational view of an implementation of an electrode probe. [Figure 3] FIG. 2 is a partial elevational view of the shaft of the electrode probe. [Figure 4] FIG. 2 is a partial perspective view of a distal portion of the shaft of the electrode probe. [Figure 5] 5 is a cross-sectional view of the electrode probe of FIG. 4 taken along line 5-5. [Figure 6] 6 is a cross-sectional view of the electrode probe of FIG. 4 taken along line 6-6. [Figure 7] 7 is a cross-sectional view of the electrode probe of FIG. 5 taken along line 7-7. [Figure 8] FIG. [Figure 9] FIG. 2 is an elevation view of the emitter. [Figure 10] FIG. 10 is a detailed view of the emitter of FIG. 9 within circle 10-10. [Figure 11] FIG. 10 shows an electrode probe deployed within a vertebral body for ablation of a bone tumor. [Figure 12] FIG. 10 shows an electrode probe deployed within a vertebral body for ablation of a nerve in the vertebral body. DETAILED DESCRIPTION OF THE INVENTION

[0017] FIG. 1 illustrates an ablation system 20 for radio frequency (RF) ablation of tissue. The ablation system 20 includes a console 22, at least one electrode probe 24, and, optionally, at least one injection module 26. For procedures in which more than one probe 24 can be used simultaneously, the ablation system 20 can further include a cable attachment 28 to which each probe 24 is individually and detachably coupled. The described electrode probe 24 is a self-grounding bipolar electrode probe, in which a proximal emitter 30 is electrically isolated from a distal emitter 32 and configured to pass RF energy therebetween to heat and cauterize tissue. Alternatively, embodiments of the present disclosure can be provided on a monopolar electrode assembly including a single emitter connected to a ground source, e.g., a ground pad.

[0018] The console 22 can include a display 34 that provides a user interface. The console 22 includes an RF energy source, e.g., an RF generator. Examples of suitable consoles are sold by Stryker Corporation (Kalamazoo, Mich.) under the trade names MultiGen (MG1), MultiGen2 (MG2), and Optablate, and are described in commonly owned International Publication No. WO2018 / 0200254, published November 1, 2018, International Publication No. WO2020 / 0198150, published November 5, 2020, and International Application No. PCT / US2022 / 038635, filed July 28, 2022, the contents of each of which are incorporated herein by reference in their entirety.

[0019] 2 and 3 , the electrode probe 24 includes a handle or hub 36 and a shaft 38 coupled to and extending from the hub 36. The hub 36 can be sized and shaped to be ergonomically manipulated by a physician. For example, the hub 36 can include a neck 40 oriented along the longitudinal axis of the shaft 38 and a body 42 formed with the neck 40. The body 42 can be oriented at an angle such that it slopes downward and proximally from the neck 40 and can be sized to be held between the physician's index and middle fingers and thumb. The shaft 38 can extend from the neck 40 of the hub 36. The hub 36 can include a power coupler configured to be detachably coupled to a power line 44, or the power line 44 can extend from the body 42. The power line 44 can also transmit data between the console 22 and the electrode probe 24. Similarly, the hub 36 includes a fluid coupler 46 configured to be disposed in fluid communication with the infusion module 26.

[0020] The shaft 38 may include a flexible elongate body 54 that forms at least a flexible distal portion 50 of the shaft 38. The shaft 38 may also include a proximal portion 48, which may be flexible or rigid. In the illustrated implementation, the proximal portion 48 includes a rigid sleeve 52 that coaxially overlies a portion of the elongate body 54. For example, the rigid sleeve 52 may be a hypotube from which the elongate body 54 extends. In such a configuration, the proximal portion 48 of the shaft 38 is defined between the hub 36 and a distal end 56 of the rigid sleeve 52, and the flexible distal portion 50 of the shaft 38 is defined between the distal end 56 of the rigid sleeve 52 and a distal end 57 of the elongate body 54.

[0021] The elongate body 54 may be made of a polymer, or at least partially formed from a polymer. The elongate body 54 is preferably a tube extruded from a thermoplastic elastomer, such as a polyether block amide, e.g., PEBAX 6333. Other suitable materials may include polyetheretherketone (PEEK), polytetrafluoroethylene (Teflon®), phenolic, polycarbonate, polysulfone, and polyoxymethylene, among others. The polymer may have a Young's modulus of less than 3 gigapascals (GPa). Alternatively, the elongate body 54 may be molded or shaped by other suitable manufacturing techniques and may be formed from films, fibers, fabrics, and powders. Extrusion of the elongate body 54 is particularly suited to providing one or more lumens 58, 60, 62, 64 and / or one or more grooves 66, 68, as described.

[0022] As mentioned, conventional electrode probes, particularly those with fluid injection or internal cooling, generally cannot achieve more than a minimum radius of curvature. The electrode probe 24 of the present disclosure advantageously includes a flexible distal portion 50 extending to the distal end 57 of the electrode probe 24. In other words, the elongated body 54 may be a unitary structure constructed from a flexible polymer, with the proximal and distal emitters 30 and 32 coupled to the elongated body 54. Conventional electrode probes, which may be somewhat flexible, such as those used in cardiac ablation, do not allow the device to achieve sufficient curvature for posterior access within the vertebral body, among other procedures requiring more acutely curved access. The insufficient flexibility of conventional electrode probes is due, in part, to the stiffness of the emitter itself. In other words, the emitter is formed from a conductive material, typically metal, and therefore the stiffness associated with metal emitters prevents conventional electrode probes from achieving larger curvatures. The electrode probe 24 of the present disclosure advantageously overcomes these drawbacks by forming the proximal emitter 30 and the distal emitter 32 with slots 70. The slots 70 are formed to impart flexibility to the emitters 30, 32 themselves. Thus, in addition to the flexibility of the elongate body 54, the emitters 30, 32 are also flexible, allowing the electrode probe 24 to achieve greater curvature when deployed over the access cannula 100 for tighter curves, such as within a vertebral body.

[0023] FIG. 4 shows in more detail the proximal and distal emitters 30, 32 coupled to the flexible distal portion 50 of the elongate body 54. Because the flexible distal portion 50 is made of a polymer, the emitters 30, 32 can be secured to the flexible distal portion 50 by a crimping process or, preferably, a swaging process. The swaging process deforms the flexible distal portion 50 by compressive forces from the inner surface 74 of the emitters 30, 32 to the outer surface 72 of the elongate body 54. Grooves 66, 68 can extend longitudinally along the elongate body 54 and are positioned radially opposite one another around the elongate body 54. Alternatively, it is contemplated that more or fewer grooves can be provided and radially arranged in any suitable configuration. The grooves 66, 68 are configured to promote improved engagement with the emitters 30, 32 that are swaged onto the elongate body 54. More specifically, during the swaging process, the ridges adjacent the grooves 66, 68 can deform toward or into the grooves 66, 68 to provide a secure friction or interference fit, causing the emitters 30, 32 to become flush or sub-flush with the outer surface 72 of the elongate body 54. Figure 4 generally illustrates the deformation associated with the swaging process due to deformation of the portions of the elongate body 54 adjacent the ends 78 of the emitters 30, 32.

[0024] The cross-sectional views of Figures 5-7 illustrate some of the internal structures and components of the electrode probe 24. The extrusion of the elongate body 54 can include at least one lumen. An exemplary implementation includes a first lumen 58, a second lumen 60, a third lumen 62, and a fourth lumen 64. The lumens 58, 60, 62, and 64 can be equiangularly arranged as shown in the axial cross-sectional view of Figure 7, although other positional configurations are contemplated. The lumens 58, 60, 62, and 64 can have the same or different diameters, and the angular position can be based on the number or size of the lumens 58, 60, 62, and 64. The lumens 58, 60, 62, and 64 can extend longitudinally parallel to one another within the elongate body 54 and cannot be in fluid communication with one another.

[0025] A proximal lead 80 is disposed within the first lumen 58. The proximal lead 80 is electrically conductive and is secured to the proximal emitter 30. More specifically, the proximal lead 80 extends through the first lumen 58, passes through an opening 84 defined by the elongate body 54, and is joined to the interior 74 of the proximal emitter 30. Similarly, a distal lead 82 can be disposed within the second lumen 60 and secured to the distal emitter 32. The distal lead 82 extends through the second lumen 60, passes through another opening 86 defined by the elongate body 54, and is joined to the interior 74 of the distal emitter 32. Joining the proximal and distal leads 80, 82 to their respective ones of the proximal and distal emitters 30, 32 can be achieved by a welding process, for example, a laser welding process.

[0026] The proximal and distal leads 80, 82 extend proximally into the hub 36. The proximal and distal leads 80, 82 are configured to be electrically connected to an RF energy source via the power line 44. RF energy supplied to the emitters 30, 32 via the proximal and distal leads 80, 82 generates an RF pathway, and therefore an ablation zone, when applied adjacent to target tissue in the anatomy. To do so, the emitters 30, 32 are axially spaced apart from one another and are of opposite polarity. A portion of the elongate body 54 forms an insulating spacer 90 between the proximal and distal emitters 30, 32. For example, in an implementation in which the elongate body 54 is formed from PEBAX, the elongate body 54 itself is non-conductive and thus forms the insulating spacer 90. The emitters 30, 32 are therefore electrically isolated without the need for a separate insulating spacer, which may require mechanical coupling means such as adhesives, threading, or lap joints. In addition to increasing flexibility and reducing manufacturing complexity and cost, such a configuration eliminates interfaces associated with the risk of infusion fluid infiltration, particularly with bending the electrode probe 24 at larger bend angles and sharper curvatures.

[0027] A thermocouple 88 may be disposed within the third lumen 62. The thermocouple 88 may be secured to the elongate body 54 within the third lumen 62 by, for example, adhesive, an internal cap, or other joining means. Alternatively, the distal end of the thermocouple 88 may be embedded within the elongate body 54. The thermocouple 88 is configured to extend into the hub 36 and be electrically connected to the console 22. The thermocouple 88 is configured to sense a temperature indicative of the extent of heating of the target tissue. The console 22 may adjust parameters of the ablation procedure, such as the amount of RF energy delivered, based on the temperature sensed by the thermocouple 88.

[0028] The fourth lumen 64 may be an infusion lumen. The elongate body 54 may define an infusion port 92 in fluid communication with the fourth lumen 64. The infusion port 92 is defined by the elongate body 54 and is configured to be disposed in fluid communication with the fluid coupler 46 on the hub 36 when coupled to the fluid coupler 46, and further disposed in fluid communication with the infusion module 26. The illustrated implementation shows the infusion port 92 positioned in a portion of the elongate body 54 that forms the insulating spacer 90 between the emitters 30 and 32. Other locations for the infusion port 92 are contemplated, such as proximal to the proximal emitter 30 and / or at the distal end 57 of the electrode probe 24. More than one infusion port may be provided.

[0029] The multi-lumen configuration prevents possible damage to the electrical components from infusion fluids. Furthermore, because the elongate body 54 itself provides a barrier separating the lumens 58, 60, 62, and 64, the flexibility of the elongate body 54 is substantially not sacrificed and there is less concern about damaging the internal sub-components or the interfaces therebetween. As mentioned, extruding the elongate body 54 accommodates intricate internal geometries (i.e., lumens 58, 60, 62, and 64) without significant manufacturing complexity. This is particularly important given the dimensions and tolerances of the elongate body 54 and its geometry. For example, the elongate body 54 can have an outer diameter within the range of approximately 1.75 to 2.25 millimeters (mm), and more particularly, within the range of approximately 1.90 to 2.00 mm. The lumens 58, 60, 62, 64 may have the same or different inner diameters, with exemplary inner diameters being within a range of approximately 0.40 to 0.60 mm, more specifically, within a range of approximately 0.45 to 0.50 mm. Additionally, the wall thickness (w) (see FIG. 7) defined between adjacent pairs of lumens 58, 60, 62, 64 may be within a range of approximately 0.10 to 0.15 mm, more specifically, approximately 0.125 mm. The openings 84, 86 and / or the inlet 92 may have a diameter within a range of approximately 0.40 to 0.5 mm, more specifically, approximately 0.45 mm. The openings 84, 86 may be spaced apart from one another by a distance within a range of approximately 5.0 to 8.0 mm, more specifically, within a range of approximately 6 to 7 mm. The distal ends of lumens 58, 60, 62, 64 may terminate short of distal end 57 of electrode probe 24, leaving a tip region of approximately 1 millimeter. Finally, grooves 66, 68 may be formed with a radius of approximately 0.1 mm. Such geometries and tolerances may not be cost-effectively achievable with other manufacturing techniques.

[0030] FIG. 8 is a perspective view of an emitter, e.g., the proximal emitter 30 or the distal emitter 32. The emitters 30, 32 may be the same or different and will be referred to hereinafter in the singular. The emitters 30, 32 include an inner surface 74 and an outer surface 76 opposite the inner surface 74. The thickness (t) of the emitters 30, 32 is defined between the inner surface 74 and the outer surface 76, and the inner diameter (ID) of the emitters 30, 32 is defined by the inner surface 74. The thickness can be within a range of approximately 0.05 to 0.10 mm, more specifically, within a range of approximately 0.07 to 0.08 mm. The inner diameter can be sized such that the elongated body 54 penetrates the emitter 30, 32 during assembly with an insertion force of less than 1 pound. An exemplary range for the inner diameter is approximately 1.8 to 2.1 mm, more specifically, approximately 1.9 to 2.0 mm.

[0031] As mentioned, the emitters 30, 32 are formed with a plurality of slots 70 to maintain flexibility. More specifically, the emitters 30, 32 can be at least 6 millimeters long, whereas without the slots 70, such a significant length would not provide the flexibility required for certain clinical applications. By virtue of the slots 70, the emitters 30, 32 can be at least 8, 10, or 12 millimeters long, or even longer. The emitters 30, 32 can be relatively long in implementations in which the electrode probe 24 is unipolar. Furthermore, as described, the slots 70 are sized such that the slots 70 remain sufficiently defined to provide the necessary flexibility despite material deformation caused by crimping or swaging the emitters 30, 32 onto the flexible distal portion 50 of the shaft 38. Referring simultaneously to FIGS. 9 and 10 , the emitters 30, 32 include a slotted portion 93 and an end portion 94 disposed opposite the slotted portion 93. The slotted portion 93 can assume 60, 70, 80 percent or more of the length of the emitters 30, 32. For example, the end portions 94 can each have a length in the range of approximately 0.90 to 1.10 mm. In certain implementations, one of the leads 80, 82 is secured to one of the end portions 94 of the emitters 30, 32. For example, the lead 80, 82 can be laser welded to a distal end portion of the end portion 94, as shown in FIG. 5.

[0032] The slots 70 can be formed by a laser cutting process or another suitable manufacturing process. The slots 70 can be formed using tailored parameters to provide the desired flexibility while allowing the emitters 30, 32 to be secured to the flexible distal portion 50 by a swaging process. With reference to FIG. 10 , the parameters can include the kerf (k), slot pitch (P), cut angle (α), and uncut angle (β). The kerf can be defined as the width or size of each slot 70 before the swaging process. The kerf can be in the range of approximately 0.015 to 0.035 mm, and more specifically, approximately 0.025 mm.

[0033] The kerf is sized so that the slot 70 narrows during the swaging process without substantially sacrificing the flexibility of the emitters 30, 32. More specifically, the swaging process can be a rotary swaging process, a roller swaging process, or a radial forging process, in which dies are used to reduce the inner and outer diameters of the emitters 30, 32 on the elongated body 54. The slot 70 provides the clearance necessary for deformation of the conductive material without creating the "fins" between the dies that are often associated with certain processes, such as crimping. As a result, after the swaging process, the outer surface 76 of the emitters 30, 32 is at least flush (or subflush) with the outer surface 72 of the elongated body 54 and features a smooth contour. The slot 70 narrows during deformation, for example, to about 0.01 mm, while remaining large enough to provide flexibility to the flexible distal portion 50. It is contemplated that the slots 70 may have the same or different kerfs. For example, the slots 70 closer to the center of the slotted portion 93 may be wider or narrower than the slots 70 closer to the end portions 94 .

[0034] With continued reference to FIG. 10 , the slot pitch of the slots 70 can be defined as the distance between adjacent longitudinal slots 70. In other words, each time the laser cutter rotates around the emitter 30, 32, it is moved axially by the slot pitch. As can be seen from the slight tilt when viewing the elevational view, the laser cutting process can produce a spiral-like pattern along the length of the emitter 30, 32. In exemplary implementations, the slot pitch is within a range of approximately 0.150 to 0.400 millimeters, more specifically, within a range of 0.165 to 0.215 mm, and even more specifically, approximately 0.191 mm. The slot pitch can be regular, such that the slots 70 are evenly spaced axially along the length of the emitter 30, 32, or irregular, such that the slots 70 are unevenly spaced.

[0035] A cut angle (α) of the slots 70 can be defined between the opposing ends 96 of each slot 70. A non-cut angle (β) of the slots 70 can be defined between the opposing ends 96 of circumferentially adjacent slots 70. The cut and non-cut angles are defined relative to the coaxial center (C) of the emitters 30, 32 and are annotated in FIG. 10 for illustrative purposes. From a practical standpoint, the cut and non-cut angles are characterized by the arc relative to the slot 70 in the laser cutting process and the arc relative to the portion of the emitter 30, 32 between the “next” circumferential slot. In other words, the laser cutting process involves cutting a slot 70, pausing, and then again cutting the next circumferential slot 70 as the laser cutter moves about the emitter 30, 32 (or the emitter 30, 32 rotates and advances). The cutting angle may be in the range of about 50 to 100 degrees, more particularly in the range of about 62 to 88 degrees, and even more particularly about 82 degrees. The non-cutting angle may be in the range of about 10 to 30 degrees, and more particularly in the range of about 18 to 21 degrees.

[0036] In light of the aforementioned features of the electrode probe 24, an inventive method of manufacturing the electrode probe 24 is provided. Specifically, the method may include extruding a polymer to include an outer surface 72 and at least one of the lumens 58, 60, 62, 64. The polymer forms the flexible distal portion 50 of the shaft 38. Emitters 30, 32 formed from a conductive material are provided, and slots 70 are formed through the conductive material using a laser cutting process. The emitters 30, 32 are positioned over the outer surface 72 of the flexible distal portion 50. The emitters 30, 32 are swaged to the outer surface 72 by a swaging process, which narrows the slots 70 and reduces the diameter of the emitters 30, 32. Lead wires 80, 82 are positioned within the lumens of the flexible distal portion 50 and secured in electrical communication with the emitters 30, 32 by a welding process. The shaft 38 is secured to the hub 36. In implementations where there is a second emitter 30, 32, certain counterpart steps may be repeated.

[0037] In certain implementations, the laser cutting process further includes advancing the emitters 30, 32 a fixed distance each time the laser cutter rotates about the emitters 30, 32 to define a slot pitch. The slot pitch may be within a range of 0.150 to 0.400 mm, or more specifically, 0.191 mm. The laser cutting process may include laser cutting the slots 70 to include opposing ends 96 that define a cut angle that is within a range of 50 to 90 degrees, or more specifically, 82 degrees. The laser cutting process may further include not laser cutting a portion between the ends 96 of adjacent slots 70 circumferentially of the emitters 30, 32 to define a non-cut angle that is within a range of 10 to 30 degrees, or more specifically, approximately 21 degrees. The cutting and non-cutting steps may be performed in an alternating, repeated fashion as the emitters 30, 32 advance during the laser cutting process.

[0038] In certain implementations, the swaging process further includes swaging the emitters 30, 32 flush below the flexible distal portion 50 so that the flexible distal portion 50 is at least partially compressed. In other words, the outer diameter of the emitters 30, 32 can be smaller than the outer diameter of the elongated body 54 adjacent to the emitters 30, 32. The feed rate of the swaging operation can be set within a range of 0.5 to 5.0 millimeters per second. The swaging operation can be performed at 55 hertz. The swaging process can also narrow the slot 70 until the kerf is approximately 0.01 millimeters. In certain implementations, the method includes pre-crimping the emitters 30, 32 after positioning the emitters 30, 32 over the outer surface 72 of the flexible distal portion 50.

[0039] In certain implementations, the conductive material of the emitters 30, 32 is annealed. The annealing step can be performed to soften the conductive material and improve the radiopacity of the emitters 30, 32 before the swaging step. Alternatively, the emitters 30, 32 can be formed from stainless steel, more particularly, fully hardened stainless steel. The method can include electroplating the emitters 30, 32 with a radiopaque material before swaging the emitters 30, 32 onto the outer surface 72 of the flexible distal portion 50. The radiopaque material can be gold or platinum-iridium, although other radiopaque materials are contemplated. Additional radiopaque elements can be included in appropriate locations to aid in placement of the electrode probe 24 under fluoroscopic guidance.

[0040] The electrode probe 24 of the present disclosure facilitates treatment of tissue in anatomical locations previously inaccessible with conventional devices. More specifically, the flexibility of the elongate body 54 and emitters 30, 32 provides access to the posterior portion of the vertebral body by achieving a larger and / or sharper radius of curvature. Referring now to FIGS. 11 and 12 , an access cannula 100 can be directed through the pedicle to provide access within the vertebral body (VB). An introduction device including a conduit assembly 102 can be deployed offset from the longitudinal axis (L) of the access cannula 100. Suitable introduction devices are disclosed in commonly owned U.S. Patent No. 9,839,443, issued December 12, 2017, and commonly owned U.S. Patent Application Publication No. 2022 / 066743, published March 31, 2022, the entire contents of each of which are incorporated by reference. The conduit assembly 102 includes a flexible conduit 104 that curves through the cancellous bone within the vertebral body.

[0041] The electrode probe 24 is directed through a flexible conduit 104. The flexibility of the electrode probe 24 allows it to follow the flexible conduit 104 through bends of at least 60 degrees, more particularly at least 90 degrees, and even more particularly at least 120 degrees. Furthermore, the electrode probe 24 is sufficiently flexible to be deployed through bends having a radius of curvature within a range of about 20 to 65 mm, and more particularly within a range of about 30 to 55 mm.

[0042] The RF energy source of the console 22 is activated to ablate the target tissue. FIG. 11 shows the electrode probe 24 deployed to ablate a bone tumor (T) contralateral to the pedicle through which the access cannula 14 is directed. FIG. 12 shows the electrode probe 24 deployed significantly posteriorly to access the nerve trunk of the vertebral nerve (BVN). It will be appreciated that the ablation system 20 of the present disclosure can be used in any suitable anatomical location, including bony and non-bony applications. Exemplary non-bony applications include facet rhizotomy, sacroiliac nerve block, genicular nerve block, etc.

[0043] Certain inventive aspects of the present disclosure will be understood with reference to the following illustrative examples.

[0044] Item 1 - A method of manufacturing a radiofrequency ablation electrode probe, the method comprising: extruding a polymer that forms a flexible distal portion of the shaft of the electrode probe to include an outer surface and a lumen; providing an emitter formed from a conductive material; forming a slot through the conductive material by a laser cutting process; positioning the emitter over the outer surface of the flexible distal portion; swaging the emitter onto the outer surface by a swaging process that narrows the slot and reduces the diameter of the emitter; positioning a lead wire within the lumen of the flexible distal portion; securing the lead wire in electrical communication with the emitter by a welding process; and securing the shaft to a hub.

[0045] Item 2 - The method of item 1, wherein the slot is laser cut to have a width in the range of 0.020 to 0.030 millimeters.

[0046] Item 3 - The method of items 1 or 2, wherein the laser cutting step further includes advancing the emitter a fixed distance per rotation of the laser cut about the emitter to define a slot pitch, the slot pitch being within the range of 0.150 to 0.400 millimeters.

[0047] Item 4 - The method of item 3, wherein the slot pitch is about 0.191 millimeters.

[0048] Item 5 - The method of any one of items 1 to 4, wherein the laser cutting step further includes laser cutting a slot including opposing ends to define a cut angle, the cut angle being in the range of 50 to 90 degrees.

[0049] Item 6 - The method of item 5, wherein the cutting angle is 82 degrees.

[0050] Item 7 - The method of item 5 or 6, wherein the laser cutting step further includes not laser cutting portions of the emitter between ends of circumferentially adjacent slots to define a non-cut angle, the non-cut angle being in the range of 10 to 30 degrees.

[0051] Item 8 - The method of item 7, wherein the non-cutting angle is 21 degrees.

[0052] Item 9 - The method of item 7 or 8, further comprising alternating and repeating the steps of laser cutting the slot and not laser cutting the portion as the emitter advances during the laser cutting process.

[0053] Item 10 - The method of any one of items 1 to 9, further comprising electroplating the emitter with a radiopaque material prior to the step of swaging the emitter onto the outer surface of the flexible distal portion.

[0054] Item 11 - The method according to item 10, wherein the radiopaque material is gold or platinum iridium.

[0055] Item 12 - The method of any one of items 1 to 9, further comprising annealing the conductive material of the emitter.

[0056] Item 13 - The method of any one of items 1 to 12, further comprising pre-crimping the emitter after the step of positioning the emitter over the outer surface of the flexible distal portion.

[0057] Item 14 - The method of any one of items 1 to 13, wherein the swaging operation further includes setting the emitter feed rate to between 0.5 and 5.0 millimeters per second.

[0058] Item 15 - The method of any one of items 25 to 38, wherein the swaging action is performed at about 55 hertz.

[0059] Item 16 - The method of any one of items 1 to 14, wherein the swaging step further comprises swaging the emitter flush downward such that the flexible distal portion is at least partially compressed.

[0060] Item 17 - The method of any one of items 1 to 16, wherein the swaging step narrows the slot until the kerf is about 0.01 millimeters.

[0061] The foregoing disclosure is not exhaustive or intended to limit the invention to any particular form. The terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings, and the invention may be practiced otherwise than as specifically described.

Claims

1. A radiofrequency ablation electrode probe, Hub and a shaft extending from the hub, defining at least one lumen, and including a flexible distal portion; a lead disposed within the lumen and configured to be electrically connected to an RF energy source; an emitter coupled to the lead and formed from a conductive material, the emitter being swaged onto the flexible distal portion of the shaft; Equipped with an electrode probe, wherein the emitter includes a slotted portion defining a plurality of slots dimensioned such that swaging the emitter onto the flexible distal portion of the shaft deforms the conductive material to reduce a diameter of the emitter.

2. 2. The electrode probe of claim 1, wherein said emitter further comprises end portions disposed opposite said slotted portion, said lead wire being welded to one of said end portions.

3. The electrode probe of claim 2 , wherein the lead wire is laser welded to a distal end portion of the end portion.

4. 4. The electrode probe of claim 1, wherein the thickness of the emitter defined between the outer and inner diameters is in the range of 0.05 to 0.10 millimeters.

5. An electrode probe according to any one of claims 1 to 4, wherein the emitter has a length of at least 8 millimetres.

6. A radiofrequency ablation electrode probe, Hub and a shaft extending from the hub, defining a lumen and including a flexible distal portion; a lead disposed within the lumen and configured to be electrically connected to an RF energy source; an emitter coupled to the lead, the emitter being formed from a conductive material and coupled to the flexible distal portion of the shaft; Equipped with an electrode probe, wherein the emitter comprises a slotted portion defining a plurality of slots and an end portion disposed opposite the slotted portion, the lead wire being secured to one of the end portions.

7. The electrode probe of claim 6 , wherein the lead wire is laser welded to a distal end portion of the end portion.

8. A radiofrequency ablation electrode probe, Hub and a shaft extending from the hub, defining at least one lumen, and including a flexible distal portion; a lead disposed within the lumen and configured to be electrically connected to an RF energy source; an emitter coupled to the lead, formed from a conductive material, having a length of at least 8 millimeters, and coupled to the flexible distal portion of the shaft; Equipped with 1. An electrode probe, wherein the emitter comprises a slotted portion defining a plurality of slots, the slotted portion having a slot pitch defined as the distance between longitudinally adjacent slots, the slot pitch being in the range of 0.150 to 0.400 millimeters.

9. The electrode probe of claim 8 , wherein the slot pitch is 0.191 millimeters.

10. A radiofrequency ablation electrode probe, Hub and a shaft extending from the hub, defining at least one lumen and including a flexible distal portion; a lead disposed within the lumen and configured to be electrically connected to an RF energy source; an emitter coupled to the lead, formed from a conductive material, having a length of at least 8 millimeters, and coupled to the flexible distal portion of the shaft; Equipped with the emitter includes a slotted portion defining a plurality of slots circumferentially disposed about an outer surface of the emitter, a cut angle defined between opposite ends of each of the slots, the cut angle being within a range of 50 to 90 degrees.

11. The electrode probe of claim 10 , wherein the cut angle is 82 degrees.

12. 12. The electrode probe of claim 10 or 11, wherein a non-cutting angle is defined between the ends of each of circumferentially adjacent slots, said non-cutting angle being in the range of 10 to 30 degrees.

13. An electrode probe according to any one of claims 6 to 12, wherein the emitter is swaged onto the flexible distal portion of the shaft.

14. 14. The electrode probe of claim 1, wherein the width of the slot is in the range of 0.020 to 0.030 millimeters prior to swaging the emitter onto the flexible distal portion.

15. An electrode probe according to any preceding claim, wherein the emitter is hardened steel and the emitter is electroplated with one of gold or platinum iridium.

16. An electrode probe according to any preceding claim, wherein the conductive material is annealed.

17. The electrode probe of any one of claims 1 to 16, wherein the flexible distal portion defines an inlet configured to be placed in fluid communication with a source of infusion liquid.

18. A radiofrequency ablation electrode probe, Hub and a shaft extending from the hub, defining a lumen and including a flexible distal portion; a first lead disposed within a first one of the lumens and configured to be electrically connected to an RF energy source; a second lead disposed within a second one of the lumens and configured to be electrically connected to an RF energy source; a distal emitter coupled to the first lead and formed from a conductive material; a proximal emitter coupled to the first lead and formed from a conductive material; Equipped with the proximal and distal emitters are coupled to the flexible distal portion of the shaft; an electrode probe, wherein each of the proximal and distal emitters includes a slotted portion defining a plurality of slots, and a section of the flexible distal portion between the proximal and distal emitters is an insulating spacer;

19. The electrode probe of claim 18 , further comprising a thermocouple disposed within a third of the lumens.

20. 20. The electrode probe of claim 18 or 19, wherein the section of the flexible distal portion defines an inlet in fluid communication with a fourth one of the lumens.

21. 21. An electrode probe according to any one of claims 18 to 20, wherein the proximal emitter and the distal emitter are each swaged onto the flexible distal portion of the shaft.

22. 22. The electrode probe of claim 1, wherein the shaft further comprises a rigid sleeve disposed over a proximal portion of the shaft from which the flexible distal portion extends, the rigid sleeve being secured to the hub.

23. The electrode probe of any one of claims 1 to 22, wherein the flexible distal portion is formed from a polymer, optionally from PEBAX.

24. 24. The electrode probe of any one of claims 1 to 23, wherein the flexible distal portion defines at least one longitudinal groove configured to facilitate coupling of the emitter to the shaft.

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