Bone access systems, devices, and methods

Abstract

A medical device for forming a channel in bone includes an induction cannula having a longitudinally positioned hypotubule, the distal hypotubule having an induction lumen through which it is positioned. The medical device also includes a curved cannula having a long tube, the long tube having a curved cannula lumen through which it is positioned, the long tube having a proximal straight portion and a distal curved portion (225), and the long tube being configured to be received into the induction lumen of the induction cannula; and a stylet having a long shaft, the long shaft having a proximal straight portion and a distal curved portion (227), and the long shaft being configured to be received into the curved cannula lumen. The distal curved portion of the stylet is released from the substantially cylindrical shape of the stylet.

Description

Technical Field

[0001] This specification describes various implementations of systems and methods for accessing and / or modulating tissue (e.g., systems and methods for accessing and / or ablating nerves or other tissue within or surrounding the vertebral body to treat chronic low back pain). A system or kit of access tools for accessing a target treatment location within the vertebral body is also provided. The access tool may include, for example, a curved J-stylet configured to provide a sufficient curved trajectory to reach a target treatment site within the vertebral body at different vertebral levels of the spine and having different bone densities while allowing for easy removal from a curved cannula.

Background Art

[0002] Back pain is a very common health problem worldwide and a major factor in work-related disability benefits and injury compensation. At any given time, low back pain affects nearly 30% of the U.S. population, resulting in 62 million people visiting hospitals, emergency rooms, outpatient clinics, and physician offices annually. Back pain can be caused by strained muscles, ligaments, or tendons in the back, and / or structural problems with the bones or intervertebral discs. Back pain can be acute or chronic. Existing treatments for chronic back pain vary widely and include physical therapy and exercise, chiropractic treatment, injections, rest, pharmacotherapy such as opioids, analgesics or anti-inflammatory drugs, and surgical interventions such as spinal fusion, discectomy (e.g., total disc replacement), or disc repair. Existing treatments can be costly, habitual, temporary, ineffective, and / or may increase pain or require a long recovery time. In addition, existing treatments do not provide sufficient relief for most patients, and only a small percentage of patients are suitable for surgery.

Summary of the Invention

Means for Solving the Problems

[0003] The applicant's existing technology (Intracept® treatment by Relievant®) provides a safe, effective, and minimally invasive treatment targeting the basivertebral nerve for the relief of chronic spinal-derived low back pain. As disclosed herein, several embodiments provide bone access tools, additional modalities for relief for patients, and / or auxiliary technologies.

[0004] According to some embodiments, the induction system may include an induction assembly comprising an inducer cannula and an inducer stylet. The inducer stylet may be bevel-tipped, trocar-tipped, and / or diamond-tipped. The inducer stylet is configured to be received into the lumen of the inducer cannula in such a manner that its distal tip protrudes from the open distal tip of the inducer cannula, thereby forming an inducer assembly when combined.

[0005] According to some embodiments, the induction system may further include a curved cannula assembly. The curved cannula assembly may include a cannula comprising a proximal handle having a curved insertion slot and a distal polymer tube. The distal polymer tube may include a curved distal end portion having a pre-formed curve but configured to transition to a substantially straight configuration when placed under constraint (e.g., constraint by insertion through a straight induction cannula). The curved cannula assembly may further include a stylet (e.g., a J-stylet) comprising a proximal handle and a distal elongated shaft. The distal elongated shaft includes a curved distal end portion having a pre-formed curve but configured to transition to a substantially straight configuration when placed under constraint (e.g., constraint by insertion through a cannula) and a distal channeling tip. The length of the curved distal end portion of the distal elongated shaft proximal to the distal channeling tip (e.g., the springboard or platform portion) may include a circumference profile that is less than a perfect circumference profile (e.g., the circumference profile of an adjacent or near portion of the distal elongated shaft or distal channeling tip) along the length of the curved distal end portion of the distal elongated shaft proximal to the distal channeling tip, such that a larger gap exists between the outer cross-sectional dimension of the curved distal end portion of the distal elongated shaft and the inner diameter of the curved distal end portion of the cannula. A circumference profile that is less than perfect (e.g., less than circular) may include a "D" shape (e.g., as opposed to a perfect "O" shape). Thus, the overall circumference profile of the curved distal end portion of the distal elongated shaft may be asymmetrical (e.g., not uniform or constant along its entire length).

[0006] According to some embodiments, the curved distal end portion of the J-stylet may be constructed to be easily retracted from the curved cannula when the J-stylet is fully received within the curved cannula lumen during treatment. The curved distal end portion of the J-stylet may have a reduced-thickness section that is approximately 20% to 80% (e.g., 20% to 60%, 30% to 70%, 40% to 80%, or an overlapping range thereof) of the full circumferential thickness of the distal elongated shaft of the J-stylet. The reduced thickness may be achieved by removing a portion of the material of the curved distal end portion. In some embodiments, the curved distal end portion may have an inclined transition section between the reduced-thickness section and the distal channeling tip. In some embodiments, the reduced thickness may not be uniform from the proximal end to the distal end of the curved distal end portion. The reduced-thickness section may be tapered from the proximal end to the distal end of the curved distal end portion. Alternatively, the reduced-thickness section may be tapered from the distal end to the proximal end of the curved distal end portion. In other embodiments, the curved distal end portion of the J-stylet may have a slit formed along the longitudinal direction of the distal elongated shaft, which separates the flexible curved section on the outer curved side of the curved distal end portion from the flexible extension on the inner curved side of the curved distal end portion. The flexible extension may extend over a portion of the length of the flexible curved section. Alternatively, the flexible extension may extend over the entire length of the flexible curved section. In some embodiments, the curved distal end portion of the J-stylet may have a plurality of slots formed perpendicular to the longitudinal direction of the distal elongated shaft on the outer curved side of the curved distal end portion. A cutout may be formed at the proximal end of the curved distal end portion in the outer curve of the curved distal end portion. In some embodiments, the distal open tip of the curved cannula may have a beveled or angled tip (for example, a bevel that is substantially parallel to the bevel of the distal channeling tip of the J stylet when the J stylet is housed in the lumen of the curved cannula).

[0007] In Example 1, the medical device for forming a channel in bone comprises: an introducer cannula having a longitudinally positioned hypotubule, the distal hypotubule having an introducer lumen through which it is positioned; a curved cannula having a long tube, the long tube having a curved cannula lumen through which it is positioned, the long tube having a proximal straight portion and a distal curved portion, and the long tube being configured to be received into the introducer lumen of the introducer cannula; and a stylet having a long shaft, the long shaft having a proximal straight portion and a distal curved portion, and the long shaft being configured to be received into the curved cannula lumen, wherein the distal curved portion of the stylet is constructed to be retracted from the curved cannula when the stylet is received into the curved cannula lumen.

[0008] In Example 2, the distal curved portion of the stylet in the device of Example 1 has a section with reduced thickness. In Example 3, the reduced-thickness section of the device in Example 2 is 40% to 80% of the total thickness of the long shaft.

[0009] In Example 4, in the device of Example 2 or Example 3, the section with reduced thickness is formed by removing material from at least one region of the distal curved portion. In Example 5, in any of the devices in Examples 1-4, the distal curved portion has a rounded or inclined transition section between the reduced-thickness section and the distal channeling tip.

[0010] In Example 6, in the devices of Example 2 or Example 3, the reduced-thickness section is not uniform from the proximal end to the distal end of the distal curved portion. In Example 7, the reduced thickness in the device of Example 6 is tapered from the proximal end to the distal end of the distal curved portion.

[0011] In Example 8, in the device of Example 6 or Example 7, the reduced thickness is tapered from the distal end to the proximal end of the distal curved portion. In Example 9, the device of Example 1 has a distal curved portion of the stylet that has a slit formed along the length of the long shaft, and this slit separates the flexible curved section on the outer curved side of the distal curved portion from the flexible extension on the inner curved side of the distal curved portion.

[0012] In Example 10, in the device of Example 9, the flexible extension extends along a portion of the length of the flexible curved section. In Example 11, in the device of Example 9 or Example 10, the flexible extension extends along the entire length of the flexible curved section.

[0013] In Example 12, the device of Example 1 has a plurality of slots formed perpendicular to the longitudinal direction of the long shaft on the outer curved side of the distal curve.

[0014] In Example 13, the notch is formed in the device of Example 12 at the proximal end of the distal curved portion, on the outer curved portion of the distal curved portion. In Example 14, the distal opening tip of the curved cannula is a beveled tip, as is the case with the devices in Examples 1-13.

[0015] In Example 15, the distal curved tube portion of the device in Example 1 is configured to be flexible and elastic. Example 16 describes a medical device for forming a channel in bone, the medical device comprising: an introduction cannula having a longitudinally positioned hypotube, wherein the distal hypotube has an introduction lumen through which it is positioned; a curved cannula having a long tube, wherein the long tube has a curved cannula lumen through which it is positioned, the long tube having a proximal straight portion and a distal curved portion, and the long tube being configured to be received into the introduction lumen of the introduction cannula; and a stylet having a long shaft, wherein the long shaft has a proximal straight portion and a distal curved portion, and the long shaft being configured to be received into the curved cannula lumen, the distal curved portion of the stylet being relieved from the substantially cylindrical shape of the stylet.

[0016] In Example 17, the device of Example 16 has a plurality of slots formed perpendicular to the longitudinal direction of the long shaft on the outer curved side of the distal curve.

[0017] In Example 18, the device of Example 16 has a section with reduced thickness in the distal curved portion of the stylet. In Example 19, the reduced-thickness section of the device in Example 18 is 40% to 80% of the total thickness of the long shaft.

[0018] In Example 20, in the device of Example 18, the section with reduced thickness is formed by removing material from at least one region of the distal curved portion. In Example 21, the device of Example 18 has a distal curved portion with a rounded or inclined transition section between the reduced-thickness section and the distal channeling tip.

[0019] In Example 22, in the device of Example 18, the reduced-thickness section is not uniform from the proximal end to the distal end of the distal curved portion. In Example 23, the reduced thickness in the device of Example 22 is tapered from the proximal end to the distal end of the distal curved portion.

[0020] In Example 24, the reduced thickness in the device of Example 22 is tapered from the distal end to the proximal end of the distal curved portion. In Example 25, the distal curved portion of the stylet has a slit formed along the length of the long shaft, separating the flexible curved section on the outer curved side of the distal curved portion from the flexible extension on the inner curved side of the distal curved portion.

[0021] In Example 26, in the device of Example 25, the flexible extension extends along a portion of the length of the flexible curved portion. In Example 27, in the device of Example 25, the flexible extension extends along the entire length of the flexible curved section.

[0022] In Example 28, in the device of Example 27, the notch is formed at the proximal end of the distal curved portion on the outer curved portion of the distal curved portion. In Example 29, the distal open tip of the curved cannula in the device of Example 16 is a beveled tip.

[0023] In Example 30, a medical device for accessing and treating tissue within a vertebral body includes an introducer cannula having an introducer lumen through which it is disposed, a curved cannula having a proximal straight tube portion and a distal curved tube portion, the elongate tube being configured to be received within the introducer lumen of the introducer cannula, a stylet having an elongate shaft, the elongate shaft having a proximal straight portion and a distal curved portion, the elongate shaft being configured to be received within the curved cannula lumen, a high-frequency probe configured to advance through the curved cannula lumen to a target treatment site, and a high-frequency energy generator connected to the high-frequency probe and configured to provide high-frequency energy to the high-frequency probe to treat the tissue, wherein the distal curved portion of the stylet is in a state of being released from the substantially cylindrical shape of the stylet.

[0024] In Example 31, in the device of Example 30, the high-frequency probe is a flexible bipolar probe. In Example 32, in the device of Example 30, the distal curved portion of the stylet has a plurality of slots formed perpendicular to the longitudinal direction of the elongate shaft on the outer curved side of the distal curved portion.

[0025] In Example 33, in the device of Example 30, the distal opening tip of the curved cannula is a bevel tip. In Example 34, the medical device for forming a channel in bone comprises an introducer cannula having a longitudinally positioned hypotube, wherein the distal hypotube has an introducer lumen through which the introducer cannula is positioned; a curved cannula having a long tube, wherein the long tube has a curved cannula lumen through which the long tube is positioned, wherein the long tube has a proximal straight portion and a distal curved portion, and the long tube is configured to be received into the introducer lumen of the introducer cannula; and a stylet having a long shaft, wherein the long shaft has a proximal straight portion and a distal curved portion, and the long shaft is configured to be received into the curved cannula lumen, wherein the distal curved portion of the stylet has a plurality of slots formed perpendicular to the longitudinal direction of the long shaft.

[0026] In Example 35, the device of Example 34 has multiple slots located on the outer curved side of the distal curved portion. To summarize this disclosure, several aspects, advantages, and novel features of embodiments of the disclosure are described herein. It should be understood that not all such advantages can necessarily be achieved according to any particular embodiment of the disclosure provided herein. Therefore, embodiments disclosed herein may be embodied or performed in a manner that achieves or optimizes one or more advantages or groups of advantages taught or suggested herein, without necessarily achieving other advantages that can be taught or suggested herein.

[0027] The method summarized above and further elaborated below describes specific actions performed by the implementer; however, it should be understood that these may also include instructions for those actions by another party. Thus, an action such as “applying thermal energy” includes “ordering the application of thermal energy.” Further embodiments of the embodiments of this disclosure are discussed in the following parts of this specification. With respect to the drawings, elements of one drawing may be combined with elements from other drawings. [Brief explanation of the drawing]

[0028] [Figure 1] This specification shows various vertebral levels and vertebrae that can be treated by the systems and methods described herein. [Figure 2] This shows an exemplary kit or system of access tools configured to access the vertebral body. [Figure 3A] Figures 3A–3C include various diagrams of the introduction cannula for the kit or system shown in Figure 2. [Figure 3B] Figures 3A–3C include various diagrams of the introduction cannula for the kit or system shown in Figure 2. [Figure 3C] Figures 3A–3C include various diagrams of the introduction cannula for the kit or system shown in Figure 2. [Figure 3D] Figure 3D is a side view of the introduction stylet of the kit or system shown in Figure 2, and Figure 3E is a side view of the distal cutting tip of the introduction stylet. [Figure 3E] Figure 3D is a side view of the introduction stylet of the kit or system shown in Figure 2, and Figure 3E is a side view of the distal cutting tip of the introduction stylet. [Figure 3F] Figures 3F–3H show the proximal portion of the introducer assembly of the kit or system shown in Figure 2. [Figure 3G] Figures 3F–3H show the proximal portion of the introducer assembly of the kit or system shown in Figure 2. [Figure 3H] Figures 3F–3H show the proximal portion of the introducer assembly of the kit or system shown in Figure 2. [Figure 3I] Figure 3I is a side view of the curved cannula of the kit or system shown in Figure 2, and Figure 3J is a top view thereof. [Figure 3J] Figure 3I is a side view of the curved cannula of the kit or system shown in Figure 2, and Figure 3J is a top view thereof. [Figure 3K] Figure 3K is a side view of the J-stylet of the kit or system in Figure 2, and Figures 3L and 3M show a side view and perspective view of the curved distal end portion of the J-stylet in Figure 3K. [Figure 3L] Figure 3K is a side view of the J-stylet of the kit or system in Figure 2, and Figures 3L and 3M show a side view and perspective view of the curved distal end portion of the J-stylet in Figure 3K. [Figure 3M] Figure 3K is a side view of the J-stylet of the kit or system in Figure 2, and Figures 3L and 3M show a side view and perspective view of the curved distal end portion of the J-stylet in Figure 3K. [Figure 3N] Figures 3N and 3O show the insertion of the J stylet (Figures 3K-3M) into the curved cannula (Figures 3I and 3J). [Figure 3O] Figures 3N and 3O show the insertion of the J stylet (Figures 3K-3M) into the curved cannula (Figures 3I and 3J). [Figure 3P] Figures 3A-3C show the insertion of the curved cannula assembly of the kit or system shown in Figure 2 into the introduction cannula. [Figure 3Q] This is a side cross-sectional view of the proximal portion of the induction cannula and the curved distal end portion of the curved cannula assembly. [Figure 3R] Figures 3R and 3S illustrate the operation of the curved cannula gears in Figures 3I and 3J in relation to the insertion of the curved cannula assembly into the induction cannula. [Figure 3S] Figures 3R and 3S illustrate the operation of the curved cannula gears in Figures 3I and 3J in relation to the insertion of the curved cannula assembly into the induction cannula. [Figure 3T] Figures 3T and 3U illustrate the bail operation of the J-stylet shown in Figures 3K–3M, which facilitates the insertion and retraction of the J-stylet from the curved cannula. [Figure 3U] Figures 3T and 3U illustrate the bail operation of the J-stylet shown in Figures 3K–3M, which facilitates the insertion and retraction of the J-stylet from the curved cannula. [Figure 3V] Figure 2 is a side view of the linear stylet of the kit or system. [Figure 3W]Figure 3W is a side cross-sectional view of the distal end portion of a straight stylet. [Figure 3WW] This is a side cross-sectional view of an alternative embodiment of the distal end portion of a straight stylet. [Figure 3X] Figures 3X and 3Y show optional drilling devices for the kit or system shown in Figure 2. [Figure 3Y] Figures 3X and 3Y show optional drilling devices for the kit or system shown in Figure 2. [Figure 3Z] This shows the induction drill fully inserted into the induction cannula. [Figure 4A] This shows a detailed cross-sectional view of the curved distal end of the curved cannula and the curved distal end of the J-stylet fully engaged with it. [Figure 4B] A detailed side view of the curved distal end portion of a J-stylet, which has an inclined transition from the curved distal end portion to the distal channeling tip portion, is shown. [Figure 4C] Figure 4B shows a cross-sectional view of the curved distal end. [Figure 4D] Figure 4B shows a detailed side view of the distal channeling tip. [Figure 4E] A detailed side view of the curved distal end of the J-stylet shows the reduced thickness. [Figure 4F] Figure 4E shows a cross-sectional view of the curved distal end. [Figure 4G] A detailed side view of the curved distal end of a J-stylet with tapered thickness is shown. [Figure 4H] Figure 4G shows a cross-sectional view of the proximal end of the curved distal end. [Figure 4I] Figure 4G shows a cross-sectional view of the distal end of the curved distal end. [Figure 4J] A detailed side view of the curved distal end of the J-stylet is shown, where material has been removed in the outer curvature of the curved distal end near the distal end. [Figure 4K] Figures 4K and 4L show detailed side views of the curved distal end portion of a J-stylet, which has a slit formed at the distal channeling tip, respectively. [Figure 4L]Figures 4K and 4L show detailed side views of the curved distal end portion of a J-stylet, which has a slit formed at the distal channeling tip, respectively. [Figure 4M] A detailed side view of the curved distal end of the J-stylet is shown, where material has been removed in the outer curvature of the curved distal end. [Figure 4N] A detailed side view of the curved distal end of the J-stylet engaged with the curved distal end of the curved cannula is shown, where the open distal end of the curved cannula is beveled. [Figure 5A] Figures 5A–5H illustrate various steps in how to access and treat tissue within a vertebral body using one or more access tools from the kit or system shown in Figure 2. [Figure 5B] Figures 5A–5H illustrate various steps in how to access and treat tissue within a vertebral body using one or more access tools from the kit or system shown in Figure 2. [Figure 5C] Figures 5A–5H illustrate various steps in how to access and treat tissue within a vertebral body using one or more access tools from the kit or system shown in Figure 2. [Figure 5D] Figures 5A–5H illustrate various steps in how to access and treat tissue within a vertebral body using one or more access tools from the kit or system shown in Figure 2. [Figure 5E] Figures 5A–5H illustrate various steps in how to access and treat tissue within a vertebral body using one or more access tools from the kit or system shown in Figure 2. [Figure 5F] Figures 5A–5H illustrate various steps in how to access and treat tissue within a vertebral body using one or more access tools from the kit or system shown in Figure 2. [Figure 5G] Figures 5A–5H illustrate various steps in how to access and treat tissue within a vertebral body using one or more access tools from the kit or system shown in Figure 2. [Figure 5H]Figures 5A–5H illustrate various steps in how to access and treat tissue within a vertebral body using one or more access tools from the kit or system shown in Figure 2. [Figure 6] An example of a high-frequency generator is shown. [Modes for carrying out the invention]

[0029] Some embodiments of this disclosure will be better understood by referring to the following drawings, which are for illustrative purposes only. Some implementations described herein concern systems and methods for modulating nerves within or adjacent to bone (e.g., around bone). In some implementations, chronic back pain is treated or prevented by modulating intraosseous nerves (e.g., basivertebral nerves) within the bones of the spine (e.g., vertebral bodies). Vertebral bodies may be located at any level of the vertebral column (e.g., cervical, thoracic, lumbar, and / or sacral). Figure 1 schematically shows the vertebral column and various vertebral segments or levels. Multiple vertebral bodies may be treated in a single visit or procedure (simultaneously or sequentially). Multiple vertebral bodies may be located within a single vertebral segment (e.g., sacral segment (e.g., S1 and S2) or lumbar segment (e.g., L3, L4, and / or L5) or two adjacent vertebral bodies in a thoracic or cervical segment) or within different vertebral segments (e.g., the L5 vertebra in a lumbar segment and the S1 vertebra in a sacral segment). It is also possible to modulate intraosseous nerves within bones other than vertebral bodies. For example, nerves within the humerus, radius, femur, tibia, calcaneus, tarsal bones, hip joint, knee, and / or phalanges can be regulated.

[0030] In some practices, the nerve being regulated is an extraosseous nerve located outside the vertebral body or other bone (e.g., before the nerve enters or exits the bone's foramen). In addition to nerves, or instead, other tissues (e.g., tumors or other cancerous tissue or fractured bone) may also be treated or otherwise affected. Parts of nerves within or over the intervertebral disc, which are one or more vertebral endplates or between adjacent vertebral bodies, can be regulated.

[0031] Nerve or other tissue modulation may be performed to treat one or more indications, including but not limited to chronic low back pain, upper back pain, acute back pain, arthralgia, intraosseous tumors, and / or fractures. Nerve modulation may also be performed in combination with bone fusion or arthrodesis to provide a synergistic effect or a complete, all-in-one, "one-and-done" procedure that does not require further surgical or minimally invasive intervention.

[0032] In some implementations, intraosseous fractures may be treated in addition to denervation and / or tumor resection by applying heat or energy and / or delivering drugs or bone graft materials to the bone. For example, bone morphogenetic proteins and / or bone cement may be delivered in conjunction with vertebroplasty or other procedures to treat fractures or to promote bone growth or bone healing. In some implementations, in a combined procedure, energy is applied, followed by the delivery of drugs and / or bone graft materials. In some embodiments, vertebral compression fractures (which may be caused by osteoporosis or cancer) are treated in conjunction with energy delivery to modulate nerves and / or cancerous tissue to treat back pain.

[0033] In some embodiments, the systems and methods for treating back pain or promoting nerve modulation of intraosseous nerves described herein may be performed without surgical resection, without general anesthesia, without cooling (e.g., without cooling fluid), and / or without substantial blood loss. In some embodiments, the systems and methods for treating back pain or promoting nerve modulation of intraosseous nerves described herein may facilitate easy retreatment as needed. In some embodiments, successful treatment is possible even in difficult-to-reach or hard-to-access locations, and access can be modified according to bone structure or different bone anatomy. One or more of these advantages also apply to the treatment of tissues outside the spine (e.g., other orthopedic uses or other tissues).

[0034] Access to the vertebral body How to access Various access methods can be used to access the vertebral body or other bones. In some procedures, the vertebral body is accessed transpedicleally (through one or both pedicles). In other procedures, the vertebral body is accessed extrapedicleally or parapedicleally (e.g., without crossing the pedicle or without crossing adjacent to the pedicle). In some procedures, the vertebral body is accessed using an extreme lateral approach or a transforaminal approach, as used in XLIF and TLIF interbody fixation procedures. In some procedures, an anterior approach is used to access the vertebral body.

[0035] In some implementations, the vertebral body may be accessed transforaminally through the basivertebral foramen. Transforaminal access via the spinal canal may involve the insertion of a “nerve explorer” or nerve locator device and / or imaging / diagnostic tool to avoid damaging spinal nerves during the entry of access tools or therapeutic devices. Nerve locator devices may comprise handheld stimulation systems such as the Checkpoint Stimulator and Locator offered by Checkpoint Surgical® or the EZstim® peripheral nerve stimulator / nerve locator offered by Avanos Medical, Inc. Nerve explorers or nerve locator devices may advantageously identify sensitive nerves that access tools should avoid, thus preventing the risk of paralysis or spinal cord injury during access to the target treatment site. Nerve locator devices may be configured to determine whether nerves are present in the region between two points or locations by applying a stimulation signal between the two points or locations and evaluating the response. The neuro-locator device may include bipolar or unipolar stimulating electrodes. In some implementations, the neuro-locator feature may be mounted on top of the access tool or the therapeutic device itself, as opposed to a separate, standalone device.

[0036] Access Tools The access tool may include an induction assembly comprising a lateral cannula and a sharpened stylet, a medial cannula configured to be introduced through the lateral cannula, and / or one or more additional stylets, curettes, or drills to facilitate access to intraosseous locations within the vertebral body or other bones. The access tool (e.g., lateral cannula, medial cannula, stylet, curette, drill) may have a pre-curved distal end portion, or may be actively maneuverable or curved. Any of the access tools may have a beveled tip, or otherwise a sharp tip, or they may have a blunt or rounded non-traumatic distal tip. A curved drill may be used to facilitate the formation of a curved access pathway within the bone. Any of the access tools may be advanced along a guidewire in some implementations.

[0037] In some implementations, a lateral cannula assembly (e.g., an induction device assembly) includes a straight lateral cannula and a straight stylet configured to be received within the lateral cannula. The lateral cannula assembly may be initially inserted, penetrating the lateral cortical shell of the bone and providing a conduit for a tool to access the medial cancellous bone. A medial cannula assembly may include a cannula having a pre-curved or maneuverable distal end portion and a stylet having a corresponding pre-curved or maneuverable distal end portion. Multiple stylets with distal end portions having different curvatures may be provided in the kit and selected by the clinician. Alternatively, the medial cannula assembly may be configured to remain straight and uncurved.

[0038] Referring to Figure 2, in one implementation, the access tool kit or system includes an accessor assembly 110 consisting of an accessor cannula 112 and an accessor stylet 114, a curved cannula assembly 210 consisting of a curved cannula 212 and a J-stylet 214, and a straight stylet 314. The accessor stylet 114 may have a beveled tip, a trocar tip, and / or a diamond tip. The accessor stylet 114 is configured to be received into the lumen of the accessor cannula 112 in such a way that its distal tip protrudes from the open distal tip of the accessor cannula 112, thereby forming the accessor assembly 110 when combined. The J-stylet 214 is configured to be received within the lumen of the curved cannula 212, with its distal end protruding from the open distal end of the curved cannula 212, thereby forming a curved cannula assembly 210 when combined. The curved cannula 212 and the J-stylet 214 may each comprise a straight proximal body portion and a curved distal end portion. The curvature of the curved distal end portions of the curved cannula 212 and the J-stylet 214 may correspond to each other. The straight stylet 314 is a flexible channeling stylet that is delivered through the curved cannula 212 and then configured to form and maintain a straight or nearly straight path as it extends from the open distal end of the curved cannula 212.

[0039] The access tool in Figure 2 may be formed from various rigid and flexible materials. The straight hypotube portion of the introducer cannula 112 may be formed from a rigid and stiff material, such as metal, hard plastic, ceramic, or composite material. The proximal handle portion of the introducer cannula 112 at the proximal end may be formed from a plastic material or another suitable material capable of withstanding impact from the mallet. The straight rod or shaft portion of the introducer stylet 114 may be formed from a rigid and stiff material, such as metal, hard plastic, or ceramic, and the proximal handle portion of the introducer stylet 112 may be formed from a plastic material or a material capable of withstanding impact. The same material may be applied to different parts of the curved cannula assembly 210, including the curved cannula 212 and J-stylet 214, as well as the straight stylet 314.

[0040] However, the curved distal end portions of the curved cannula 212 and J-stylet 214, as well as at least the distal end portion of the straight stylet 314, may be formed from a flexible and elastic material. The flexibility and elasticity of the access tool may depend on its dimensions, particularly its cross-sectional dimensions, and the material from which it is formed. In some embodiments, these flexible and elastic portions of the access tool may be formed from one or more plastic materials, such as polyamide (PA), polyethylene terephthalate (PET), polycarbonate (PC), polyoxymethylene (POM), acrylonitrile butadiene styrene (ABS), polyethylene (PE), polypropylene (PP), and polyimide (PI). In some embodiments, the flexible and elastic portions may be formed from a metal alloy, such as nitinol. In some embodiments, when the cross-sectional dimensions are relatively thick, they may also be formed from one or more rigid plastic elastomers, such as polyethylene-based polyolefin elastomers, polypropylene-based elastomers, thermoplastic polyester elastomers, thermoplastic polyurethane elastomers, nitrile butadiene rubber, and thermoplastic vulcanized polymers. For example, the distal portion of a straight rod 156 may be a solid rod formed from a plastic elastomer having a high Shore durometer measurement. In some embodiments, when the elastic tool portion has a small cross-sectional dimension or tubular structure to facilitate bending, it may be formed from a semi-rigid material, as adequate flexibility can be achieved using a semi-rigid material when the cross-sectional dimensions are sufficiently small. Furthermore, to make the rigid portion more flexible, it may be provided with a chevron-shaped design or pattern, or slits or holes in the thickness direction.

[0041] The access tool may include one or more additional introducer cannulas 112, one or more additional introducer stylets 114 (e.g., with different tip sections such as those with a beveled tip and those with a diamond tip or trocar tip), one or more additional curved cannulas 212 (e.g., having a curved distal end section with a different curvature than the first curved cannula), one or more additional J-stylets 214 (e.g., having different curvatures or different designs configured to access bone of different hardness), an introducer drill 440, and / or an additional straight stylet 314 (e.g., having a different length than the first straight stylet), and may be provided as a kit. Some kits may include add-on components or accessory kit modules for accessing hard bone (e.g., introducer drills 440 and J-stylets 214 specifically configured for accessing hard bone). Some kits may include additional access tool components or accessory kit modules adapted for accessing one or more additional vertebrae within the same or different vertebral segments. The kit may also include one or more (e.g., at least two) therapeutic devices (such as radiofrequency energy delivery probes).

[0042] In some embodiments, access tools (e.g., kits) may be specifically designed and adapted to facilitate access to hard, non-osteoporotic bone (e.g., bone surrounding or within the vertebral body, such as the cervical, thoracic, lumbar, or sacral vertebrae). Hard bone may be determined based on bone mass density testing, compressive strength determination, compressive modulus determination, imaging techniques, or tactile sensations perceived by the operator as the access instrument is advanced. In some practices, hard bone may be determined as bone having a bone mineral density score (e.g., a T-score greater than or equal to -1) within the standard deviation of a normal, healthy young adult. In some practices, hard bone may be identified as bone having a compressive strength greater than 4 MPa and / or a compressive modulus greater than 80 MPa for trabecular bone. For cortical bone, the compressive strength may exceed 5.5 MPa and the compressive modulus may exceed 170 MPa.

[0043] Figures 3A–3C show various diagrams of embodiments of the induction cannula 112. The induction cannula 112 includes a proximal handle 116 and a distal hypotube 118 extending from the proximal handle 116. The illustrated proximal handle 116 has a “chimney-like” or “T-handle” design configuration adapted to provide sufficient finger clearance and gripping portion (e.g., one finger on each side of the lower flange 113 of the proximal handle 116, along the underside of the crossbar portion 115) for easy removal. However, alternative design configurations for the proximal handle other than the “chimney-like” or “T-handle” design may be incorporated.

[0044] The proximal handle 116 includes an upper central opening 120 configured to facilitate linear axial insertion of an introducer stylet 114 or other linear access tool. The upper central opening 120 is positioned to correspond to (e.g., coaxial with) a central lumen 137 extending through the hypotube 118 of the introducer cannula 112, and can facilitate insertion of a linear instrument (e.g., an introducer stylet 114 or a steerable cannula or steerable stylet) through it. The proximal handle 116 may also include coupling features 121 (e.g., recesses, notches, grooves, tabs) to facilitate coupling or mating between the proximal handle 216 of the introducer stylet 114 and the proximal handle 116 of the introducer cannula 112. The connecting feature 121 may be adapted to prevent rotation of the induction stylet 114 and / or to ensure that the distal tip 125 of the induction stylet 114 extends beyond the open distal tip 122 of the hypotube 118 of the induction cannula 112. Thus, penetration of the distal tip 125 of the induction stylet 114 is facilitated through the bone. The upper surface of the proximal handle 116 of the induction cannula 112 also includes a curved lateral slot 117 and a curved ramp 141 to facilitate insertion of the curved cannula assembly 210 into and along the proximal handle 116, and subsequently into the central lumen of the hypotube 118, as will be further described below.

[0045] The central lumen 137 of the hypotube 118 extends from the proximal handle 116 to the open distal end 122 of the hypotube 118. The hypotube 118 may be flared or tapered so that its diameter is not constant along its entire length. For example, the diameter may decrease sharply at a certain distance (e.g., 1 cm to 3 cm) from the lower edge of the lower flange 113 of the proximal handle 116 to form a sharply narrowing edge 119, which then continues distally with a constant diameter. In another embodiment, the diameter may decrease gradually along the length of the hypotube 118 from the lower edge or edge 119 of the lower flange 113 to the open distal end 122 of the hypotube 118 (e.g., uniformly tapered). The central lumen 137 of the hypotube 118 may be coated with a medical-grade silicone lubricant to improve tool insertion and removal. The outer diameter of the hypotube 118 may be in the range of approximately 4.2 mm to 4.5 mm, for example, 3 mm to 5 mm. As shown in Figure 3C, the lower (bottom) side of the proximal handle 116 of the inletting cannula 112 may include a notch 124 that is adapted to receive a portion of the flexible shaft of a therapeutic device (e.g., a radio frequency probe made of nitinol or other flexible or shape memory material), to hold it in place and out of the way during the therapeutic procedure, thereby reducing the stack height (e.g., approximately 3 inches / 75 mm or more).

[0046] Figures 3D–3H show various diagrams and parts of an embodiment of the introduction stylet 114. Figure 3D shows a side view of the introduction stylet 114. The introduction stylet 114 includes a proximal handle 126 and a distal elongated member or shaft 128. The proximal handle 126 has an upper surface adapted for being driven in by a mallet and a lower surface adapted for facilitating removal of the introduction stylet 114 by the operator. The length of the distal elongated member 128 may range from 125 mm to 300 mm (e.g., 125 mm to 200 mm, 175 mm to 250 mm, 200 mm to 225 mm, 215 mm to 300 mm). The distal end portion 132 of the introduction stylet 114 may include a scalloped section 133 (as shown in detail in Figure 3E) to provide a release mechanism for bone compression. The wavy section 133 may be designed to have a lateral profile that is generally hourglass-shaped. The wavy section 133 may be formed to gradually taper from the proximal portion of the full diameter to the narrowest intermediate portion, and then gradually widen to the distal portion of the full diameter. The taper may be symmetrical or asymmetrical. The wavy section 133 may include one wavy section (or hollowed-out area) or multiple wavy sections (or hollowed-out areas) along the length of the distal end portion 132. The distal tip 125 of the distal end portion 132 may have a full diameter suitable for crushing bone (e.g., pedicle bone, cortical bone of the vertebral body). When bone is fractured by the distal tip 125 of the distal end portion 132, bone fragments or chips may become lodged in the gap formed between the distal end portion 132 of the induction stylet 114 and the inner surface of the distal end portion of the induction cannula 112, thereby making it more difficult to remove the induction stylet 114 from the induction cannula 112. According to some embodiments, the wavy section 133 of the induction stylet 114 advantageously provides a place for bone fragments and pieces to fall during removal of the induction stylet 114, thereby facilitating easier removal of the induction stylet 114.

[0047] Figures 3F to 3H show the introducer assembly 110 after the introducer stylet 114 has been inserted into the introducer cannula 112. As described above, the proximal handle 116 of the introducer cannula 112 may include a mating or engaging feature (e.g., a coupling feature 121) to facilitate automatic (e.g., snap-fit) engagement between the introducer stylet 114 and the proximal handle 116 of the introducer cannula 112.

[0048] The proximal handle 126 of the induction device stylet 114 includes an alignment indicator 129, an anti-rotation tab 131, and a push button 134. As best shown in Figure 3G, the alignment indicator 129 is configured to align with a corresponding alignment indicator 130 on the upper surface of the crossbar portion 115 of the proximal handle 116 of the induction device cannula 112 to ensure proper insertion and alignment of the induction device stylet 114 relative to the induction device cannula 112. The anti-rotation tab 131 is positioned within a slot 117 of the proximal handle 116 of the induction device cannula 112 and is configured to prevent rotation of the induction device stylet 114 relative to the induction device cannula 112 during insertion and orientation.

[0049] The push button 134 is integrally coupled to the anti-rotation tab 131, and pressing the push button 134 extends the anti-rotation tab 131 from its constraint in the slot 117, thereby allowing the induction stylet 114 to rotate relative to the induction cannula 112 (as shown in Figure 3H). Pressing the push button 134 also disengages the induction stylet 114 from the induction cannula 112, allowing the induction stylet 114 to be removed from the induction cannula 112. The proximal handle 126 of the induction stylet 114 may include an internal ramp (not shown) configured to provide a mechanical advantage in assisting the removal of the induction stylet 114 from the induction cannula 112 as the proximal handle 126 is rotated (e.g., 120 degrees counterclockwise) (especially when bone fragments become lodged in the gap between the induction stylet 114 and the induction cannula 112, making removal more difficult). The combination of the wavy distal end section design and the internal ramp within the proximal handle 126 can provide a 50% to 70% reduction in removal force compared to a full-diameter distal end section design (e.g., without the wavy section) that does not have a ramp within the proximal handle 126.

[0050] Figures 3I and 3J show a side view and a top view of an embodiment of the curved cannula 212. The curved cannula 212 includes a proximal handle 216, a threaded proximal shaft portion 220, a gear 221, a rigid support portion 223, and a distal flexible shaft portion 224. The proximal handle 216 includes a curved slot 217 and a curved ramp 231 configured to facilitate the insertion of a J-stylet 214 into and along the central lumen 237 of the curved cannula 212, which extends from the proximal handle 216 to the open distal tip 222 of the distal flexible shaft portion 224. The central lumen 237 of the curved cannula 212 may be coated with a medical-grade silicone lubricant to improve tool insertion and removal.

[0051] In the illustrated example, the gear 221 has a female thread configured to engage with a corresponding male thread on the threaded proximal shaft portion 220 such that the rotation of the gear 221 causes controlled proximal or distal translation of the gear 221 along the threaded proximal shaft portion 220. The threaded proximal shaft portion 220 is sized so that when the gear 221 is in its most distal position, the distal tip 222 of the curved cannula 212 does not extend beyond the open distal tip 122 of the introducer cannula 112 when the curved cannula assembly 210 is fully inserted therein. The gear 221 may rotate freely about the threaded proximal shaft portion 220. The thread may include a triple thread. The gear 221 may be configured to traverse the entire length of the threaded proximal shaft portion 220 in a full four-turn rotation of the gear 221.

[0052] The rigid support portion 223 may comprise a biocompatible metal or other rigid material such as stainless steel, titanium, platinum, and / or equivalent, to provide further support to the curved cannula 212 during insertion of the J-stylet 214. The distal flexible shaft portion 224 may be composed of a thermoplastic shape memory polymer material (such as polyetheretherketone (PEEK), polyurethane, polyethylene terephthalate (PET), and / or equivalent). The distal end portion 225 may be pre-curved (e.g., shaped) to have a predetermined curve in a “static” or unconstrained configuration.

[0053] Figures 3K to 3M show one embodiment of the J-stylet 214. Figure 3K shows a side view of the J-stylet 214 in a “stationary” normal unrestrained configuration or state, and Figures 3L and 3M are enlarged views (side view and perspective view, respectively) of the curved distal end portion 227 of the J-stylet 214. The J-stylet 214 comprises a proximal handle 226 and a distal elongated shaft 218. The proximal handle 226 has an upper surface adapted to be driven in by a mallet and a lower surface adapted to allow the J-stylet 214 to be easily removed by two or more (e.g., two, three, or four) fingers of the operator. The upper surface of the proximal handle 216 includes an alignment indicator 219 (for example, shown in Figure 3P) configured to align with the corresponding alignment indicator 130 of the induction cannula 112 in order to facilitate the insertion, removal, and deployment of the J-stylet 214 (and curved cannula assembly 210).

[0054] The distal elongated shaft 218 includes a curved distal end portion 227 having an asymmetrical curvature profile along its length (for example, the curved distal end portion 227 does not have a constant full diameter along its length). The distal channeling tip 228 is sized and shaped to facilitate channeling through cancellous bone along a curved path or trajectory. The curved distal end portion 227 comprises a flexible curved section 229 having a “D-shaped” cross-sectional profile, for example, as shown by the cross-sectional profile in Figure 4C. The cross-sectional view of the “D-shaped” cross-sectional profile of the curved section 229 may be a partial circle. The curved section 229 may be formed by mechanical grinding or cutting of a cylindrical wire until a desired D-shaped cross-sectional profile is achieved, with the top (e.g., upper) surface of the curved section 229 being substantially smooth and flat, before the curve is formed. The thickness of the curved section 229 (e.g., vertical cross-sectional dimensions), a predetermined set angle or radius of curvature, and the start and end points of the flexible curved section 229 along the length of the curved distal end portion 227 may be modified to provide J-stylets with different stiffness and bending properties for different levels of vertebrae or bone of different densities.

[0055] According to several embodiments, an asymmetrical curved profile (e.g., a profile with a D-shaped cross-section) advantageously provides improved cephalad-caudal steering because the curved distal end portion 227 bends primarily inward and not laterally. In addition, the design and materials of the curved distal end portion 227 of the J-stylet 214 may allow the angle of curvature of the curved distal end portion 227 to remain relatively consistent and repeatable across varying bone densities or regardless of the bone environment. For example, in one embodiment, the design and materials of the curved distal end portion 227 of the J-stylet 214 facilitate consistent and repeatable access to posterior positions (e.g., the posterior half of the vertebral body, or a position approximately 30% to 50% of the distance between the posterior and anterior ends of the vertebral body along the sagittal axis, or the geometric center or midpoint within the vertebral body in the case of vertebral bodies with varying bone densities, or other desired target positions within the vertebral body or other bones). According to some embodiments, the curvature is designed to deviate by less than 25 degrees (e.g., less than 20 degrees, less than 15 degrees, less than 10 degrees) or less than 30% from a predetermined set curvature of the curved distal end portion 227 in an unrestrained configuration (even in hard bone such as bone from non-osteopenic or non-osteoporotic conditions).

[0056] Various embodiments of the curved section 229 may exist to improve performance during surgery and / or to facilitate removal of the J-stylet 214 from the curved cannula 212, as will be further described below.

[0057] The J-stylet 214 may be designed and adapted to exert lateral forces of 6 pounds (2.73 kg) to 8 pounds (3.63 kg). The curvature of the curved section 229 of the curved distal end portion 227 may result in an angle between the central longitudinal axis of the straight proximal portion of the distal elongated shaft 218 and the axis of the distal channeling tip portion 228 in the normal unconstrained state. This angle may be 65 to 80 degrees (e.g., 65, 70, 75, 80 degrees, or any other value within the enumerated range). The radius of curvature of the curved section 229 may be in the range of 11.5 mm to 15 mm (e.g., 11.5 mm to 12 mm, 12 mm to 12.5 mm, 12 mm to 13 mm, 12.5 mm to 14 mm, 13 mm to 14 mm, 13.5 mm to 15 mm, their overlapping range, or any value within the enumerated range). J Stylet 214 can contain plastic materials, nitinol, and other flexible metal alloy materials.

[0058] Figures 3N and 3O are perspective and side cross-sectional views, respectively, showing the insertion of the curved distal end portion 227 of the J-stylet 214 into the slot 217 of the proximal handle 216 of the curved cannula 212. As shown in Figure 3O, the slot 217 includes a curved ramp 231 and a straight vertical backstop support 233 (without, for example, a trumpet-shaped section) to facilitate the insertion of the curved distal end portion 227 of the J-stylet 214. As described above, the curved cannula 212 has rigid support portions 223 extending in and out of the threaded shaft portion 220 to provide further support when inserting the J-stylet 214 into the central lumen 237 of the curved cannula 212.

[0059] Figures 3P and 3Q show the insertion of the curved cannula assembly 210 into the induction cannula 112. The curved distal end portion 225 of the curved cannula assembly 210 is inserted at a lateral angle into the slot 117 in the proximal handle 116. The lateral angle may be about 65 to 75 degrees with respect to the central longitudinal axis LA of the distal hypotube 118 of the induction cannula 112, and for example, in one embodiment, with an initial angle of about 70 degrees. During insertion, the curved distal end portion 225 may follow the central lumen 137 of the distal hypotube 118 of the induction cannula 112 along the ramp 141 in the slot 117. The gear 221 of the curved cannula 212 may be at its most distal position along the threaded proximal portion 220 of the curved cannula 212 during insertion. Therefore, the curved distal portion 225 of the curved cannula assembly 210 can be prevented from inadvertently advancing beyond the open distal tip 122 of the induction cannula 112 until the operator is ready to advance further.

[0060] Referring to Figure 3Q, an enlarged side cross-sectional view is shown of the proximal portion of the induction cannula 112 and the curved distal portion 225 of the curved cannula assembly 210. As shown, the induction cannula 112 is molded to provide a backstop support 143 that is substantially aligned with the inner surface of the central lumen 137 of the hypotube 118. Thus, the curved distal end portion 225 of the distal flexible shaft portion 224 of the curved cannula 212 cannot swirl out of the induction cannula 112 during insertion. According to some embodiments, the asymmetrical “D-shaped” cross-sectional profile of the J-stylet 214 may be advantageously designed to avoid twisting during insertion.

[0061] Figures 3R and 3S illustrate the operation of the gear 221 of the curved cannula 212. As shown in Figure 3R, prior to the insertion of the curved cannula assembly 210 into the induction cannula 112, the gear 221 is rotated along the threaded proximal portion 220 to its distal position, preventing accidental advancement of the curved distal end portion 225 of the curved cannula assembly 210 out of the induction cannula 112. As shown in Figure 3S, the gear 221 is rotated along the threaded proximal portion 220 to its nearest position, allowing for complete insertion of the curved cannula assembly 210 into the induction cannula 112. Thus, the curved distal end portion 225 of the curved cannula assembly 210 may extend from the induction cannula 112 along a curved path within the cancellous region of the vertebral body or other bone.

[0062] Figures 3T and 3U illustrate the operation of the operating mechanism of the J-stylet 214. The proximal handle 226 of the J-stylet 214 includes an actuator 250 configured to be switchable between a first “standby” or “non-operated” state and a second “operated” state. In the first state, i.e., the “non-operated” state, the actuator 250 is substantially aligned with the top surface of the proximal handle 226 (e.g., parallel or substantially parallel), as shown in Figure 3T. In the second state, i.e., the “operated” state, the actuator 250 is offset from the top surface of the proximal handle 226, as shown in Figure 3U. The actuator 250 is configured to act as a lever to cause a slight axial movement of the J-stylet 214 relative to the curved cannula 212, for example, proximal-distal movement, when the actuator 250 is pivoted. When the actuator 250 is switched to the "operated" state, the flange 253 of the actuator 250 contacts the proximal handle 216 of the curved cannula 212, retracting the J-stylet 214 proximal to the curved cannula 212. Thus, the distal channeling tip 228 of the J-stylet 214 is fully retracted within the curved cannula 212 and does not extend outward from the open distal tip 222 of the curved cannula 212. According to some embodiments, the actuator 250 is advantageously switched to the "operated" state (where the distal channeling tip 228 of the J-stylet 214 is retracted within the open distal tip 222 of the curved cannula 212) when inserting or removing the curved cannula assembly 210 from the induction cannula 112, or when inserting or removing the J-stylet 214 from the curved cannula 212 (for example, to avoid friction caused by the interaction between the two metal components). The upper surface of the actuator 250 may include an indicator 252 (e.g., a colored marking or other visual indicator) that is visible to the operator when the actuator 250 is operating, but not visible when the actuator 250 is not operating.

[0063] Figure 3V shows a side perspective view of one embodiment of the straight stylet 314. Figure 3W shows the distal portion of the straight stylet 314. The straight stylet 314 includes a proximal handle 316 and a distal elongated shaft 318. The proximal handle 316 includes an upper surface adapted for hammering with a mallet or for applying pressure with the operator's hand or fingers. As the straight stylet 314 advances through the curved cannula 212, a marker band 317 can be positioned along the distal elongated shaft 318 at a position corresponding to the position where the distal channeling tip 319 of the straight stylet 314 extends from the open distal tip 222 of the curved cannula 212. The marker band 317 may be a visual marking on the distal elongated shaft 318, and / or the marker band 317 may be radiopaque. The length of the straight stylet 314 may be sized such that, when the straight stylet 314 is fully inserted into the curved cannula 212, the length of the shaft portion of the straight stylet 314 extending beyond the open distal tip 222 of the curved cannula 212 is 25–50 mm (e.g., 25–35 mm, 30–40 mm, 35–45 mm, 40–50 mm, their overlapping range, or any value within the listed range). The diameter of the straight stylet 314 can be sized such that it is inserted into and penetrates the central lumen 237 of the curved cannula 212 with minimal frictional resistance. The distal elongated shaft 318 may comprise an internal flexible shape-memory core 360 ​​extending from the proximal handle 316 to the distal channeling tip 319 of the straight stylet 314, and a flexible (e.g., polymer) outer layer 365 extending from the proximal handle 316 to the distal end of the distal elongated shaft 318, but stopping before (or proximal to) the distal channeling tip 319. Thus, the internal core 360 ​​protrudes from the outer layer 365. The straight stylet 314 may be flexible enough to curve to traverse the curved distal end portion 225 of the curved cannula 212 without significant friction. The straight stylet 314 may also be rigid enough to maintain a straight path once it extends from the open distal end portion of the curved cannula 212.The inner core 360 ​​of the straight stylet 314 may include nitinol or other metal alloys or other flexible materials. The outer layer 365 may be made of a more rigid material, such as a metal or polymer material (e.g., PEEK, polyurethane, PET, and / or equivalents).

[0064] Figure 3WW shows an alternative embodiment of the distal portion of the straight stylet 314. The distal elongated shaft 370 may comprise an inner flexible metal braided cable 380 (e.g., made of stainless steel, nitinol, or other metal alloy) extending from the proximal handle 316 and welded to the sharp distal channeling tip 385 of the straight stylet 314; a metal hypotube 390 (e.g., made of stainless steel, nitinol, or other metal alloy) extending from the proximal handle 316 and welded to the outside of the braided cable 380; and a flexible outer layer 395 (e.g., a polymer such as PEEK, polyurethane, PET, and / or equivalent) extending from the hypotube 390 to the distal channeling tip 385. The straight stylet 314 may have sufficient flexibility to bend to traverse the curved distal end portion 225 of the curved cannula 212 without significant friction. The straight stylet 314 may also be sufficiently rigid to maintain a straight path as it extends from the open distal end of the curved cannula 212.

[0065] Figures 3X-3Z show embodiments of the access drill 440 and its interaction with the access cannula 112. Access instrument kits or systems (e.g., kits or kit modules designed for accessing hard or dense bone) may include the access drill 440 as needed. Figure 3X is a side view of one embodiment of the access drill 440. The access drill 440 may include a proximal handle 446 and an elongated drill shaft 447. The proximal handle 446 may have a substantially T-shaped design and may have a soft grip overmolded. The length of the elongated drill shaft 447 may be sized to extend 20-35 mm beyond the open distal tip of the access cannula 112 when the access drill 440 is fully inserted into the access cannula 112. The elongated drill shaft 447 may include a solid proximal portion 448 and a fluted distal portion 449.

[0066] Figure 3Y is an enlarged perspective view of the grooved distal portion 449 of the introducer drill 440 shown in Figure 3X. The grooved distal portion 449 may include a distal cutting tip 450 having a cutting angle of approximately 90 degrees. The drill flutes 452 of the grooved distal portion 449 may be fitted to taper away from the distal cutting tip 450 (this is either a reverse taper or opposite to the direction of the taper of a typical drill bit) to facilitate improved bone packing in the open flute volume as bone fragments and shards are generated by the operation of the introducer drill 440. The distal cutting tip 450 may have a tip angle of 65–75 degrees and a chisel edge angle of 115–125 degrees. Since the long drill shaft 447 is supported during use by a rigid inlet cannula 112 that surrounds at least a portion of the length of the long drill shaft (and, in most cases, a portion of the length of the grooved distal portion), the groove may, advantageously, be deeper and wider than that of a typical drill bit. The drill longitudinal groove 452 may have a helix angle of 12 to 18 degrees (e.g., 12 to 14 degrees, 13 to 15 degrees, 14 to 16 degrees, 15 to 18 degrees, their overlapping range, or any value within the enumerated range). The grooved distal portion 449 may include two longitudinal grooves having a length of 70 mm to 85 mm.

[0067] The open flute volume of the grooved distal portion 449 may be advantageously configured to retain all or substantially all (e.g., more than 75%, more than 80%, more than 85%, more than 90%) of any significant bone fragments or pieces removed by the induction drill 440 as the induction drill 440 is removed from the induction cannula 112, thereby reducing the amount of bone fragments left in the bone (e.g., vertebral body) or in the induction cannula 112. In some embodiments, the open flute volume of the grooved distal portion 449 is adapted to retain about 2 cc of bone. The grooved distal portion 449 may exhibit web tapering (e.g., an increase in width or depth, or an increase in the angle of the groove with respect to the longitudinal axis) along its length from distal to proximal (e.g., a reverse taper). The first approximately 25 mm of the most distal region may not exhibit web tapering. The web taper can then be gradually increased until it reaches the maximum web taper near the proximal end of the grooved distal portion 449, facilitating the upward (or proximal) pushing of bone fragments or bone shards along the grooved distal portion 449. For example, the grooved distal portion 449 may have a negative draft (e.g., a negative draft of about 0.77 inches or 20 mm).

[0068] Figure 3Z shows the introducer drill 440 fully inserted into and engaged with the proximal handle 116 of the introducer cannula 112. The introducer drill 440 is inserted into the central opening 120 of the proximal handle 116 of the introducer cannula 112 and sized to advance through the central lumen 137 of the hypotube 118 of the introducer cannula 112. The proximal handle 446 of the introducer drill 440 is configured to engage with the coupling or occlusal feature 121 of the proximal handle 116.

[0069] Retraction of the J-stylet from the introduction system In low-density bone, the support of the cancellous bone for the curved cannula 212 is reduced, which may make the retraction of the curved stylet (e.g., a J-stylet) 214 more difficult than in denser bone. If the support of the curved cannula at the exit of the induction cannula 112 is weak, the curved cannula 212 may locally flex laterally when the curved stylet 214 is removed. This causes the exit of the induction cannula to interact more strongly with the medial radius of the curved distal end portion 227 of the curved stylet 214 (through the curved cannula wall) as the stylet 214 is retracted into the induction cannula 112 during removal. The transition along the medial radius of the curved section may increase resistance when removing the stylet 214. Therefore, by increasing the flexibility of the curved distal end portion 227 and changing the transition shape from the curved portion to the distal channeling tip portion 228, this interaction between the stylet / introducer system can be reduced, thereby reducing the stylet's removal force.

[0070] Design improvements to the stylet 214 that allow for easier removal from the introductor cannula 112 while maintaining its primary function of forming a curved pathway within the bone may include a thinner curved distal end portion 227, a tapered curved distal end portion 227, an alternative asymmetrical cross-sectional circumferential profile of the curved distal end portion 227 (e.g., rectangular, inverted "D" shape), a flatter transition from the curved distal end portion 227 to the distal channeling tip portion 228, a curved distal end portion 227 with a full cross-sectional circumferential profile and multiple relief slots, a slot in the distal channeling tip portion 228, and a localized material relief portion located proximal to the distal channeling tip portion 228.

[0071] High-density bone can reduce lateral deployment. While the lateral deployment force of the curved stylet 214 can be increased in many ways, this can also make it more difficult for the operator with regard to inserting the curved cannula assembly into the induction cannula 112 and removing the stylet 214 from the induction cannula 112.

[0072] At some point during the procedure, it may be necessary to remove the J-stylet 214 from the introducer cannula 112 (e.g., from the curved cannula 212 inserted into the introducer cannula 112) to allow further instruments (e.g., a high-frequency treatment probe or a straight stylet or drill) to be inserted through the curved cannula 212. For example, when the distal channeling tip 228 successfully reaches the target treatment area within the bone, the J-stylet 214 may be removed from the curved cannula 212. A treatment device (e.g., a high-frequency probe) can then be inserted into the curved cannula 212 to perform tissue manipulation. As described above, retraction of the J-stylet 214 from the curved cannula 212 may cause interference between the curved distal end portion 227 of the J-stylet 214 and the central lumen 237 of the curved cannula 212. This interaction may result in significant resistance that hinders retraction, thereby making it more difficult for the operator to remove the J-stylet 214.

[0073] As shown in Figure 4A, before removing the J-stylet 214 from the central lumen 237, the curved distal end portion 227 of the J-stylet 214 is inserted into the central lumen 237 of the curved distal end portion 225 of the curved cannula 212 and channeled into the cancellous bone tissue (e.g., within the vertebral body). The curvature of the curved distal end portion 227 of the J-stylet can be pre-formed to match or coincide with the curvature of the curved distal end portion 225 of the curved cannula 212. Thus, interference between the curved distal end portion 227 of the J-stylet 214 and the curved distal end portion 225 of the curved cannula 212 is minimized and becomes negligible. When the curved distal end portion 227 of the J-stylet 214 is pulled by the proximal handle 216 and retracted into the central lumen 237 of the curved cannula 212, it moves proximal to the elongated straight portion of the curved cannula 212 from the curved distal end portion 225. As disclosed above, this elongated straight portion of the curved cannula 212, which may be formed from a flexible and elastic material, is defined by the hypotube 118 of the inlet cannula 112, which is rigid and stiff. The transition from the curved section to the straight section straightens the curved distal end portion 227 of the J-stylet 214. Thus, the distal channeling tip 228 of the J-stylet 214 may be in contact with one side of the inner surface of the central lumen 237 of the curved cannula 212, due to the pre-formed curvature of the curved distal end portion 227. For example, the transition edge 232a of the inclined transition section 232 (see Figure 4A) between the flexible curved section 229 and the distal channeling tip 228 can be pressed against and slide over the inner surface of the central lumen 237. Since the distal elongated shaft 218 of the J-stylet 214, including the curved distal end portion 227, is formed from a flexible and elastic material as disclosed above, interference between the curved distal end portion 227 of the J-stylet 214 and the central lumen 237 of the curved cannula 212 can deform the wall of the central lumen 237 either longitudinally or transversely. In the longitudinal direction, the deformation may take the form of surface wrinkles or ripples. In the transverse direction, the deformation may cause the circumference of the central lumen 237 to become slightly non-circular. In either case, the interference causes frictional resistance to proximal movement of the J-stylet 214.In certain situations, this frictional resistance can become large enough to make removing the J-stylet 214 cumbersome.

[0074] For example, in lower-density bone (e.g., osteoporotic or osteopenic bone), retraction of the J-stylet 214 may be more difficult than in higher-density bone (e.g., non-osteoporotic or non-osteopenic bone) due to reduced cancellous bone support for the curved cannula 212. Stronger support in higher-density bone may help maintain the shape of the curved cannula 212 so that the central lumen 237 is not easily deformed.

[0075] In some embodiments, the curved distal end portion 227 of the J-stylet 214 can be adjusted or modified to make removal of the J-stylet 214 from the curved cannula 212 or introduction cannula 112 easier and less cumbersome (e.g., by reducing frictional resistance and / or deformation). As shown in Figure 4B, an enlarged detailed side view of the curved distal end portion 227 of Figure 3L, this adjustment or modification can be made by reducing or decreasing the thickness 234 of at least a portion of the flexible curved section 229, as shown in Figure 4C, a cross-sectional view of the flexible curved section 229 from Figure 4B. As shown in Figure 4B, the D-shaped cross section of the flexible curved section 229 is partially circular and has a flat top surface 242a. As described above, the flexible curved section 229 may be formed by removing or discarding the top of a cylindrical wire or shaft. In some embodiments, greater flexibility of the flexible curved section 229 can be achieved by a relatively smaller thickness 234. Depending on the configuration, the thickness 234 may be 20% to 80%, for example 20% to 50%, 50% to 70%, 40% to 80%, 55% to 65%, their overlapping range, or any value within the stated range of circumferential dimensions (e.g., thickness or diameter) of adjacent regions on the proximal and distal sides of the curved distal end portion 227. Instead of percentages, the difference between thickness and diameter may be expressed as ratios, for example 2:5 to 4:5, 1:2 to 6:9, 3:5 to 5:7, or 5:9 to 2:3. In some configurations, the starting point of the curved section 229 may be 230 mm to 245 mm from the proximal end of the distal elongated shaft 218. The ending point of the curved section 229 may be between 4.5 mm and 9 mm from the distal end of the distal elongated shaft 218. In an alternative implementation, the D-shape may be flipped such that the flat surface 242a is on the bottom or outer curved surface, as opposed to the upper or inner curved surface, thereby forming an uninterrupted, uniform inner curved profile to minimize interaction with the inlet cannula 112 during removal.

[0076] In addition to, or as an alternative to, varying the thickness 234, the material of the distal elongated shaft 218, including the curved distal end portion 227, may be selected to adjust the flexibility of the curved distal end portion 227. A more flexible material may satisfy the requirement for a more flexible curved distal end portion 227. The thickness 234 may be adjusted along with the material selection to achieve optimal flexibility of the curved distal end portion 227. Generally, a more flexible curved distal end portion 227 can be advantageously adapted more easily by the straightening action when the J-stylet 214 is pulled and the curved distal end portion 227 is retracted from the curved distal end 225 of the curved cannula 212 toward the proximal straight portion of the curved cannula 212. Thus, the frictional resistance generated by the J-stylet 214 can be reduced.

[0077] However, on the other hand, if the curved distal end portion 227 of the J-stylet 214 is formed to be excessively flexible, it may not be rigid enough to penetrate hard or cancellous bone when the J-stylet 214 is driven into the bone or otherwise advanced to access it. In some implementations, it may be necessary to include different J-stylets 214 with different flexibility of the curved distal end portion 227, configured for different bone hardness or density.

[0078] Figure 4D is a detailed view from Figure 4B, showing the transition from the flexible curved section 229 to the distal channeling tip 228. The thinner flexible curved section 229 transitions to the full-size distal channeling tip 228 via the inclined transition section 232, forming a transition edge 232a and an angle between the inclined transition section 232 and the longitudinal axis of the distal channeling tip 228. As can be seen in Figure 4D, the sharper the angle, the smoother the transition between the flexible curved section 229 and the distal channeling tip 228. When the J-stylet 214 is pulled by the proximal handle 216 and the curved distal end portion 227 retracts from the curved distal end portion 225 to the proximal straight portion of the flexible shaft 224 of the curved cannula 212, the bending force of the curved distal end portion 227 may press the transition edge 232a of the curved distal end portion 227 against the inner surface of the central lumen 237 of the curved cannula 212, causing frictional resistance. A smoother transition edge 232a may have the advantage of smoother interference between the curved distal end portion 227 and the central lumen 237 of the curved cannula 212, and therefore less frictional resistance when removing the J-stylet 214 from the curved cannula 212. In some embodiments, the inclined transition section 232 may be implemented such that the angle is less than 60°, for example, less than 45° or less than 30°. In some embodiments, the transition edge 232a may be contoured or have curvature to achieve a smoother transition between the flexible curved section 229 and the distal channeling tip 228. In some embodiments, the transition section 232 has a radius of curvature as opposed to an angle. The radius of curvature may be modified as desired and / or as necessary to reduce frictional resistance when the J-stylet 214 is retracted from the curved cannula 212, and / or to allow for increased movement or flexibility of the flexible curved section 229 and / or the distal channeling tip 228. A rounded transition can advantageously reduce the removal force by having an effectively flatter transition to the distal channeling tip 228, allowing for easier insertion into the introducer cannula 112 during removal.

[0079] In some implementations, as shown in Figures 4E and 4F, the reduction or decrease in thickness 234 can be achieved by removing the lower portion along at least a portion of the outer radius of the flexible curved section 229, as shown by the cross-sectional view in Figure 4F, thereby forming a lower flat surface 242b. Thus, a portion of the curved distal end portion 227, or the entire curved distal end portion 227, may have a rectangular shape rather than a D shape. As described above, the reduction in thickness 234 increases the flexibility of the curved distal end portion 227 and potentially reduces the difficulty in removing the J-stylet 214 from the curved cannula 212.

[0080] Referring to Figures 4G to 4I, in some embodiments, the flexible curved section 229 of the curved distal end portion 227 can be formed with a variable cross-sectional thickness (for example, so that one portion of the flexible curved section 229 is more flexible than another portion or other portions, or so that the flexible curved section 229 has flexibility that varies along its length). As shown in Figure 4G, the thickness of the flexible curved section 229 is relieved so that it tapers from the proximal end 229a to the distal end 229b. Reducing the cross-sectional thickness from a thicker region 234a to a thinner region 234b at the proximal end allows the distal end portion 229b and the distal channeling tip portion 228 of the flexible curved section 229 to be more flexible. Increasing the flexibility of the distal channeling tip 228 makes it easier to straighten the distal channeling tip 228 when retracting it within the central lumen 237 of the curved cannula 212, which can make the removal of the J-stylet 214 easier. The radial transition between the flexible curved section 229 and the distal channeling tip 228 can reduce the removal force by having an effectively flatter transition to the distal channeling tip 228, making insertion into the introduction cannula 112 easier during removal.

[0081] In other configurations, the taper of the flexible curved section 229 may be reversed from that shown in Figures 4G to 4I (for example, tapered from the distal end 229b to the proximal end 229a). In this case, the more flexible portion is the proximal end 229a of the flexible curved section 229. This embodiment allows the distal channeling tip 228 to flex together with the distal end 229b of the flexible curved section 229. As a result, interference or frictional resistance may be reduced as the protrusion of the transition edge 232a is reduced when the J-stylet 214 retracts from the curved cannula 212. The radial transition between the flexible curved section 229 and the distal channeling tip 228 can reduce the removal force by having an effectively flatter transition to the distal channeling tip 228, making insertion into the introducer cannula 112 easier during removal.

[0082] In some embodiments, material may be removed from local portions of the flexible curved section 229 to increase local flexibility. In Figure 4J, the region 236 located closer to the distal end 229b of the flexible curved section 229 is relieved (i.e., the material has been removed from the outer radius of the curve). Therefore, region 236 is more flexible than the rest of the flexible curved section 229. Once constructed, the distal channeling tip 228 may have a tendency to bend together with the distal end 229b of the flexible curved section 229. The region 236 from which the material has been removed may be located anywhere on the flexible curved section 229 from the proximal end 229a to the distal end 229b.

[0083] In some embodiments, the distal channeling tip 228 can be constructed to conform to the shape deformation of the inner surface of the central lumen 237 of the curved cannula 212. Referring to Figure 4K, a relief slit or slot 244 is formed extending from the apex or top surface of the flexible curved section 229 and cutting into the distal channeling tip 228. In some embodiments, the direction of the slit or slot 244 substantially follows the longitudinal direction of the flexible curved section 229 of the distal elongated shaft 218. Thus, the flexible extension 246 is formed within the distal channeling tip 228 and separated from the flexible curved section 229 by the slit or slot 244. According to some configurations, the effect of the slot 244 is to allow greater bending of the distal channeling tip 228 while maintaining patency with respect to the inner diameter of the curved cannula 212. The increased flexibility of the tip 228 makes it easier for the curved distal end portion 227 of the stylet 214 to straighten as it enters the induction cannula 112, thus assisting the operator when removing the stylet 214. Increasing the length of the transition section at the proximal end of the flexible extension 246 facilitates insertion into the induction cannula during removal. The flexible extension 246 can bend toward the upper surface of the flexible curved section 229 when pressed by the inner surface of the central lumen 237 of the curved cannula 212, thereby easily reducing the outer cross-sectional dimensions, reducing frictional resistance, and facilitating the retraction of the J-stylet 214. In some embodiments, the transition section 232 may be rounded or beveled (as described above) for a smooth transition between the transition section 232 and the flexible extension 246 of the distal channeling tip 228. According to some embodiments, the nearest portion of the flexible extension 246 is adapted to remain within the curved cannula 212 so as not to be trapped when the J-stylet 214 is retracted into the curved cannula 212.

[0084] In some embodiments, the flexible extension 246 in Figure 4K is extended to cover a larger portion of the flexible curved section 229 (e.g., the entire flexible curved section 229, or at least the portion exceeding the length of the distal channeling tip 228), as shown in Figure 4L. In this example, the entire length of the flexible curved section 220 or the curved distal end portion 227 is covered by a material that extends the entire cross-sectional circumference (e.g., thickness, diameter). In the illustrated example, there is no transition from the thinner flexible curved section 229 to the full-circumferential distal channeling tip 228. Therefore, the frictional resistance at the transition edge described for some of the earlier examples is absent. The fact that the curved distal end portion 227 has a continuous inward curve is advantageous in that it can minimize interaction with the introducer cannula 112 during removal and thus reduce frictional resistance to retraction. In addition, interference between the curved distal end portion 227 and the inner surface of the central lumen 237 of the curved cannula 212 can be compensated by bending the flexible extension 246 toward the flexible curved section 229. In some implementations, the relief slit 244 may extend distally close to the most distal end of the J-stylet 214, thereby increasing the flexibility of the flexible extension 246.

[0085] As shown in Figure 4M, in some configurations, a smooth internal curve is achieved by an implementation that does not involve structural interruption on the internal curved side of the distal curved end portion 227. Since interference between the distal curved end portion 227 and the central lumen 237 of the curved cannula 212 generally occurs on the internal curved side, the embodiment shown in Figure 4M results in easier removal of the J-stylet 214 from the curved cannula 212. As shown in Figure 4M, the flexibility of the distal curved end portion 227 of the J-stylet 214 is achieved by forming a plurality of relief slots 245 on the external curved side. The relief slots are substantially perpendicular to the longitudinal direction of the distal curved end portion 227. Furthermore, in some implementations, a larger relief cut 247 can be formed at the proximal end of the distal curved end portion 227 to increase the overall flexibility of the distal curved end portion 227. In different implementations, the width and depth of the relief slots 245, as well as the spacing between the slots, may be adjusted for the desired or required flexibility of the curved distal end portion 227.

[0086] Improvements to the curved cannula 212 allow for greater curvature of the curved cannula assembly as it exits the induction cannula 112 and enters the bone. Modifications to the curved cannula 212 may include chamfering the tip to form a beveled face and deflecting the curved cannula 212 laterally. Referring to Figure 4N, the open distal tip 222 of the curved cannula 212 may have a beveled or angled tip, as opposed to having a straight tip. In some implementations, the bevel or angle of the open distal tip 222 of the curved cannula 212 may match or substantially match the bevel or angle of the distal channeling tip 228 of the J-stylet 214. By increasing the tip material of the curved cannula 212 on the medial curvature side, the portion of the curved cannula 212 can be reinforced, thus making the retraction of the J-stylet 214 from the curved cannula 212 easier.

[0087] Regulation of bone tissue Figures 5A–5H illustrate embodiments of steps in a method of using an access tool to facilitate access to a location within the vertebral body 500 for a procedure (e.g., regulating intraosseous nerves such as vertebral nerves, delivering bone cement for the treatment of vertebral fractures, and / or ablation of bone tumors). Referring to Figure 5A, the distal portion of the introducer assembly 110 (including the distal tip 125 of the introducer stylet 114 and the distal tip of the introducer cannula 112) is inserted through the pedicle 502 adjacent to the vertebral body 500 by driving in the proximal handle of the introducer stylet 114 after insertion and alignment engagement of the introducer stylet 114 into the introducer cannula 112.

[0088] According to some embodiments, the method may optionally include removing the introducer stylet after the initial puncture into the pedicle 502 (for example, if the operator can tell the operator that additional steps and / or tools will be needed to obtain the desired curved trajectory to access the posterior portion (e.g., the posterior half) of the vertebral body 500 once the bone density is sufficiently high or hard). Referring to Figure 5B, the method may optionally include the step of inserting the introducer drill 440 into the introducer cannula 112 and penetrating it to complete the transverse of the pedicle 502 and the penetration through the cortical bone 503 region of the vertebral body 500 to reach the cancellous bone region 504 of the vertebral body 500. The introducer drill 550 may be advanced into the cancellous bone region 504 (especially if the cancellous bone region 504 is determined to be sufficiently hard or high density), or the advance may be stopped at the boundary between the cortical bone region 503 and the cancellous bone region 504. This step may include both rotating the induction drill 440 and driving in the proximal handle 446 of the induction drill 440, or simply rotating the induction drill 440 without driving in the proximal handle 446. Referring to Figure 5C, the induction drill 440 may be removed and the induction stylet 114 may be reinserted into the induction cannula 112. Referring to Figure 5D, the induction assembly 110 may then be driven in to advance the distal tip 122 of the induction cannula 112 to the entry site into (or within) the cancellous region 504 of the vertebral body 500. The induction stylet 114 may then be removed from the induction cannula 112.

[0089] Next, the curved cannula assembly 210 may be inserted into the induction cannula 112 with the gear 221 in its most distal position to prevent the curved cannula assembly 210 from advancing prematurely and unexpectedly from the open distal tip 122 of the induction cannula 112. Referring to Figure 5E, after the gear 221 has rotated to a more proximal position, the curved cannula assembly 210 may be driven out from the distal tip 122 of the induction cannula 112 and driven forward along the curved path in the cancellous bone region 504, moving the collective curved distal end portion of the curved cannula assembly 210 forward together. Referring to Figure 5F, the J-stylet 214 may then be removed from the curved cannula 212, and the curved cannula 212 remains in place. According to some embodiments, the path formed by the preceding device is advantageous in that the curved cannula assembly 210 has a starting point and begins to curve immediately upon exiting the open distal tip 122 of the introducing cannula 112.

[0090] Referring to Figure 5G, if a further straight path beyond the curved path is desired to reach the target therapeutic location, a straight stylet 314 may be inserted through the curved cannula 212 so that the distal channeling tip 319 of the straight stylet extends beyond the open distal tip of the curved cannula 212 along a straight path toward the target therapeutic location (e.g., the vertebral trunk or vertebral foramen). In some embodiments, the straight stylet 314 may not be necessary, and this step may be omitted.

[0091] Referring to Figure 5H, a treatment device 501 (e.g., a flexible bipolar radiofrequency probe) may be inserted through the curved cannula 212 (after removal of the straight stylet 314, if used) and advanced from the open distal end of the curved cannula 212 to the target treatment site. The treatment device 501 can then perform the desired treatment. For example, if the treatment device 501 is a radiofrequency probe, the treatment device 501 may be activated to excise an intraosseous nerve (e.g., a vertebral nerve) or tumor within the vertebral body 500. Bone cement or other agents, or diagnostic devices (such as a nerve stimulator or imaging device to confirm nerve ablation), may be delivered through the curved cannula 212 after the treatment device 501 has been removed from the curved cannula 212, if necessary.

[0092] For certain patient spinal anatomies requiring a steeper curve to access a desired target therapeutic location within the vertebral body at specific levels of the spine (e.g., sacral and lumbar levels), a curette / curve introducer combination may be initially inserted to initiate a curved trajectory into the vertebra (e.g., creating an initial curve or shelf). The curette may have a pre-curved distal end portion, or the distal end portion may be configured to be controllably articulated or curved (e.g., manually by a pull wire, by rotation of a handle member coupled to one or more pull wires coupled to the distal end portion, or automatically by a robot or artificial intelligence-driven navigation system). The curette / curve introducer combination may then be removed, followed by insertion of an external straight cannula and an internal curved cannula / curved stylet assembly to continue the curve toward the target therapeutic location.

[0093] In some embodiments, either an access tool (e.g., a cannula or stylet) or a treatment device may comprise a rheological and / or magnetizable material (e.g., a magnetorheological fluid) along the distal end portion of the access tool, configured to bend in situ after insertion into a desired location within bone (e.g., a vertebra). A magnetic field may be applied to the distal end portion of the access tool and / or treatment device using the magnetizable fluid or other material, and may be adjusted or varied using one or more permanent magnets or electromagnets to bend the distal end portion of the access tool and / or treatment device toward the magnetic field. In some embodiments, a treatment probe may include a magnetic wire along a portion of its length (e.g., the distal end portion). The curvature of the magnetic wire may be increased or decreased by increasing or decreasing the voltage applied to the magnetic wire. These embodiments can advantageously facilitate controlled steering without manual pull wires or other mechanical mechanisms. The voltage may be applied by an instrument controlled and operated by an automated robotic control system.

[0094] The therapeutic device (e.g., therapeutic probe) may be any device capable of modifying tissue (e.g., nerve, tumor, bone tissue). Any energy delivery device capable of delivering energy can be used (e.g., RF energy delivery device, microwave energy delivery device, laser device, infrared energy device, other electromagnetic energy delivery device, ultrasonic energy delivery device, etc.). The therapeutic device 501 may be an RF energy delivery device. The RF energy delivery device may include a pair of bipolar electrodes at the distal end of the device. The pair of bipolar electrodes may include an active tip electrode and a return ring electrode spaced apart from the active tip electrode. The RF energy delivery device may include one or more temperature sensors (e.g., thermocouples, thermistors) positioned on or embedded in the outer surface of the shaft of the energy delivery device. The RF energy delivery device may not have internal circulating cooling according to some embodiments.

[0095] In some implementations, waterjet cutting devices may be used to modulate (e.g., denervate) nerves. For example, a waterjet cutter may be configured to produce a very fine cutting stream formed by a jet of very high-pressure water. For example, the pressure may be in the range of 15 MPa to 500 MPa (e.g., 15 MPa to 50 MPa, 30 MPa to 60 MPa, 50 MPa to 100 MPa, 60 MPa to 120 MPa, 100 MPa to 200 MPa, 150 MPa to 300 MPa, 300 MPa to 500 MPa, their overlapping range, or any value within the enumerated range). In some implementations, chemical nerve modulating tools injected into the vertebral body or endplate may be used to excise or otherwise modulate nerves or other tissues. For example, the chemical nerve modulating tool may be configured to selectively bind to nerves or endplates. In some implementations, local anesthetics (e.g., liposomal local anesthetics) may be used inside or outside the vertebral body or other bone to denervate or block nerves. In some implementations, radioactive material or implants may be placed within the vertebral body using brachytherapy, and then irradiated with sufficient radiation to excise the vertebral body or destroy the nerve. In some implementations, chymopapain injections and / or chondriase injections may be used (e.g., under local anesthesia). After the chemical or targeted agent has bound to a specific nerve or vertebral endplate, phototherapy may be used to excise or otherwise modify the nerve.

[0096] In some implementations, thermal energy may be applied within the cancellous portion of the vertebral body (e.g., by one or more RF energy delivery devices coupled to one or more radio frequency (RF) generators). The thermal energy may be conducted by heat transfer to the surrounding cancellous bone, thereby heating the cancellous portion. In some implementations, the thermal energy is applied within a specific frequency range and has a temperature sufficient to heat the cancellous bone, and is applied for a sufficient duration, so that the vertebral nerves extending through the cancellous bone of the vertebral body are modulated. In some implementations, the modification includes permanent ablation or denervation or cell perforation (e.g., electroporation). In some implementations, the modification includes transient denervation or inhibition. In some implementations, the modification includes stimulation or denervation that does not involve tissue necrosis.

[0097] With respect to thermal energy, the temperature of the thermal energy may be in the range of approximately 70 to 115 degrees Celsius (e.g., approximately 70 to 90 degrees Celsius, approximately 75 to 90 degrees Celsius, approximately 83 to 87 degrees Celsius, approximately 80 to 100 degrees Celsius, approximately 85 to 95 degrees Celsius, approximately 90 to 110 degrees Celsius, approximately 95 to 115 degrees Celsius, or an overlapping range thereof). The temperature gradient may be in the range of 0.1 to 5°C / second (e.g., 0.1 to 1.0°C / second, 0.25 to 2.5°C / second, 0.5 to 2.0°C / second, 1.0 to 3.0°C / second, 1.5 to 4.0°C / second, 2.0 to 5.0°C / second). The processing time may range from approximately 10 seconds to approximately 1 hour (e.g., 10 seconds to 1 minute, 1 minute to 5 minutes, 5 minutes to 10 minutes, 5 minutes to 20 minutes, 8 minutes to 15 minutes, 10 minutes to 20 minutes, 15 minutes to 30 minutes, 20 minutes to 40 minutes, 30 minutes to 1 hour, 45 minutes to 1 hour, or their overlapping ranges). Pulse energy may be delivered as an alternative to or in conjunction with continuous energy. With respect to high-frequency energy, the applied energy may range from 350 kHz to 650 kHz (e.g., 400 kHz to 600 kHz, 350 kHz to 500 kHz, 450 kHz to 550 kHz, 500 kHz to 650 kHz, their overlapping ranges, or any value within the enumerated ranges such as 450 kHz ± 5 kHz, 475 kHz ± 5 kHz, 487 kHz ± 5 kHz). The power of the radio frequency energy may be in the range of 5W to 30W (e.g., 5W to 15W, 5W to 20W, 8W to 12W, 10W to 25W, 15W to 25W, 20W to 30W, 8W to 24W, and their overlapping ranges, or any value within the listed ranges). According to some implementations, the thermal treatment dose (e.g., using the cumulative equivalent minutes (CEM) 43°C thermal dose calculation metric model) may be 200 to 300 CEMs (e.g., 200 to 240 CEMs, 230 CEMs to 260 CEMs, 240 CEMs to 280 CEMs, 235 CEMs to 245 CEMs, 260 CEMs to 300 CEMs) or greater than a given threshold (e.g., greater than 240 CEMs). The number of CEMs may represent the average cumulative thermal dose value at a target therapeutic area or location, or it may represent a number representing a desired dose for a particular biological endpoint. Thermal damage can occur through necrosis or apoptosis.

[0098] Cooling may be provided, if necessary, to prevent surrounding tissue from overheating during neuromodulatory procedures. The cooling fluid may be circulated internally through a delivery device to and from a fluid reservoir in a closed-circuit manner (e.g., using inlet and outlet lumens). The cooling fluid may contain pure water or saline solution having a temperature sufficient to cool the electrodes (e.g., 2–10°C, 5–10°C, 5–15°C). Cooling may be provided by the same or a separate instrument used to deliver thermal energy (e.g., heat). In some implementations, cooling is not used.

[0099] In some implementations, ablation cooling may be applied to nerve or bone tissue instead of heat (e.g., for cryoneurolysis or cryoablation applications). The temperature and duration of cooling may be sufficient to modulate intraosseous nerves (e.g., ablation or local freezing due to excessive cooling). Low temperatures can destroy the myelin coating or sheath surrounding the nerve. Low temperatures may also favorably reduce the sensation of pain. Cooling may be delivered using a hollow needle under fluoroscopy or other imaging guidance.

[0100] In some implementations, one or more fluids or agents may be delivered to a targeted therapeutic site to modulate nerves. The agents may include, for example, bone morphogenetic proteins. In some implementations, the fluids or agents may include chemicals for nerve modulation (e.g., chemosectants, alcohols, phenols, nerve inhibitors, or nerve stimulants). The fluids or agents may be delivered using a hollow needle or injection device under fluoroscopy or other imaging modalities.

[0101] One or more treatment devices (e.g., probes) may be used simultaneously or sequentially. For example, the distal ends of two treatment devices may be inserted into a vertebral body or other bone, or into different locations within different vertebral bodies or bones. A radiofrequency treatment probe may include multiple electrodes configured to act as monopolar or unipolar electrodes, or as a pair of bipolar electrodes. The treatment device may also be pre-curved or bendable so that a curved stylet is not required, or may have a sharp distal tip so that a further sharp stylet is not required. In some implementations, one or all of the access tools and treatment devices are MR-compatible so that they can be visualized under MR imaging.

[0102] One or more therapeutic devices (e.g., therapeutic devices 501 of a probe, kit, or system such as a radio frequency probe) may include an indicator configured to alert a clinician about the current operating status of the therapeutic device. For example, the indicator may include a light ring positioned along the length of the therapeutic device and extending around its circumference. The light ring may be configured to illuminate in different colors and / or to exhibit other visible effects (e.g., pulse on and off in a certain pattern). One or more therapeutic devices may also be configured to provide audible alerts (e.g., beeps with a certain frequency or intonation) corresponding to different operating states. In one embodiment, the light ring may be dim or not illuminated when the therapeutic device is not connected to a radio frequency generator or is not ready to deliver RF energy. The light ring may pulse at a first rate (e.g., one pulse every 2-3 seconds) to indicate an operating state in which the therapeutic device and generator system are ready to begin delivering RF energy. The light ring may be continuously illuminated to indicate an operating state in which the therapeutic device is actively delivering RF energy. The light ring may pulse at a second speed different from the first speed (e.g., faster, slower) when an error is detected by the generator in an operating state, or when a particular processing parameter is determined to be outside the acceptable range. In one implementation, the second speed is greater than the first speed (e.g., 2 pulses per second). Haptic feedback may also be provided to the clinician for at least some of the operating states to provide additional warnings in addition to visual warnings.

[0103] In some implementations, the treatment device (e.g., treatment device 501) includes a microchip pre-programmed with treatment parameters (e.g., duration of treatment, target temperature, rate of temperature rise). When the treatment device is electrically connected to the generator, the treatment parameters are transmitted to the generator and displayed on the generator's display, providing the clinician with confirmation of the desired treatment.

[0104] Figure 6 shows a front view of one embodiment of the generator 400 (e.g., a radio frequency energy generator). The generator 400 includes an instrument connection port 405 to which a therapeutic device (e.g., an RF energy delivery probe) can be connected. The generator 400 may be configured for use without a neutral electrode (e.g., a grounding pad). The instrument connection port 605 is surrounded by an indicator light 406 configured to illuminate when a therapeutic device is properly connected to the instrument connection port 405. As shown, the indicator light 406 may comprise a circular LED indicator light. The indicator light 406 may be configured to illuminate continuously in a single color (e.g., white, blue, green) when a therapeutic device is connected to the instrument connection port 405. The indicator light 406 may flash at a first pulse rate (e.g., 1 Hz) to prompt the clinician to connect the therapeutic device to the instrument connection port 405. The indicator light 406 may flash at a second pulse rate that is different from (e.g., faster than) the first pulse rate (e.g., 2Hz, 3Hz, 4Hz) to indicate an error condition.

[0105] The generator 400 also includes a display 408 configured to display information to a clinician or operator. During startup and use, the current status of the generator 400 and energy delivery (treatment) parameters may be displayed on the display 408. During energy delivery, the display 408 may be configured to display (alphanumeric and / or graphically) information such as remaining treatment time, temperature, impedance, and power. For example, graphs of power versus time and impedance versus time may be displayed. In one embodiment, the display may comprise a color active matrix display. The generator 400 further includes a start / pause button 410 configured to be pressed by the operator to start and stop energy delivery. The start / pause button 410 may be surrounded by a second indicator light 412, as well as an indicator light 406 surrounding the instrument connection port 405. The second indicator light 412 may also comprise a circular LED indicator light. The second indicator light 412 may be configured to remain illuminated in a single color (e.g., white, blue, or green) when the generator 400 is powered on and ready to begin energy delivery. The indicator light 412 may flash at a first pulse rate (e.g., 1 Hz) to prompt the clinician to press the start / pause button 410 to begin energy delivery. The indicator light 412 may flash at a second pulse rate different from the first pulse rate (e.g., 2 Hz, 3 Hz, or 4 Hz) (e.g., faster). The generator 400 may also be configured to output audible warnings indicating different operating conditions (e.g., to match the outputs of indicator lights 406, 412).

[0106] The generator 400 may also include a power button 414 configured to turn the generator 400 on and off, a standby power indicator light 416 configured to illuminate (e.g., illuminate green) when the AC power switch (not shown) of the generator 400 is switched on, an RF active indicator light 417 configured to illuminate (e.g., illuminate blue) during RF energy delivery, and a system failure indicator light 418 configured to illuminate (e.g., illuminate red) in a system failure condition. The generator 400 may also include user input buttons 420 (e.g., arrow buttons for switching up and down between options, and an "input" button for selecting the option desired by the user) configured to facilitate navigation and selection of options displayed on the display 408 (e.g., menu options, configuration options, confirmation requests).

[0107] Access to the lateral position of the vertebral body For access to extraosseous locations outside the bone (e.g., extraosseous locations such as the outside of the vertebral body), visualization or imaging modalities and techniques may be used to facilitate targeting. For example, the foramina of the vertebral body (e.g., vertebral foramina) may be located using MRI guidance provided by an external MR imaging system, CT guidance provided by an external tomography imaging system, fluoroscopy guidance using an external X-ray imaging system, and / or an endoscope inserted laparoscopically. After the foramina are located, it is possible to modify (e.g., resection, nerve transection, stimulation) the nerves entering through the foramina by treating the foramina (e.g., heat or energy irradiation, administration of chemical destructive agents, cryotherapy, close-range radiotherapy, and / or mechanical cutting). For example, the foramina can be located under direct visualization using an endoscope, and then the vertebral nerves can be mechanically cut near the foramina. In some implementations, the intervertebral disc and vertebral body may be denervated by treating (e.g., ablation) the sinus nerves before they branch into the vertebral nerves entering the vertebral foramina of the vertebral body. Because the vertebral endplates are made of cartilage, nerves within the vertebral endplates can be denervated by irradiating them with radiation or high-intensity focused ultrasound energy from an external position within the body.

[0108] Target identification and patient screening In some practice, it is possible to identify target or candidate vertebrae for treatment before treatment. Target or candidate vertebrae may be identified based on the identification of various types of endplate degeneration and / or defects (e.g., focal defects, erosive defects, marginal defects, angular defects, all of which can be considered pre-modic change features) or factors associated therewith. For example, one or more imaging techniques (e.g., MRI, CT, X-ray, fluoroscopy) can be used to determine whether the vertebral body or vertebral endplate exhibits active modic features or "pre-modic change" features (e.g., type 1 modic changes including findings of inflammation and edema, type 2 modic changes including bone marrow changes (e.g., fibrosis) and increased visceral fat content, features likely to cause modic changes). For example, images obtained via MRI (e.g., IDEAL MRI) can be used to identify early signs or precursors of edema or inflammation in the vertebral endplate (e.g., through the application of one or more filters) before formal characterization or diagnosis as a type 1 modic change. Examples of premodic alteration features include mechanical features (e.g., loss of soft nucleus material in the intervertebral disc adjacent to the vertebral body, decreased disc height, decreased hydrostatic pressure, microfractures, focal endplate defects, erosive endplate defects, marginal endplate defects, angular endplate defects, osteitis, spondylodiscitis, Schmol's nodules) and bacteriological features (e.g., detection of bacterial invasion into the intervertebral disc adjacent to the vertebral body, possible disc herniation or annular fibrous laceration that enabled bacterial invasion, possible bacterial inflammation or neovascularization), as well as other etiological mechanisms that indicate early signs or prodromal symptoms of potential modic alteration or vertebral endplate degeneration / defect.

[0109] Therefore, the vertebral body can be identified as a potential target for treatment before modic changes occur (or before pain symptoms themselves appear in the patient), and as a result, the patient can be proactively treated to prevent or reduce the likelihood of chronic low back pain before it occurs. In this way, the patient does not have to suffer from debilitating low back pain for a period of time before treatment. Modic changes may or may not correlate with endplate defects and may or may not be used in candidate selection or screening. According to some embodiments, modic changes are not evaluated, and only vertebral endplate degeneration and / or defects (e.g., features of pre-modic changes before the onset or before the ability to identify modic changes) are identified. The cranial and / or caudal endplates may be evaluated for pre-modic changes (e.g., endplate defects that appear before modic changes and may affect the subchondral and vertebral bone marrow adjacent to the vertebral endplate).

[0110] In some implementations, levels of biomarkers (e.g., substance P, cytokines, highly sensitive C-reactive proteins, or other compounds associated with inflammatory processes and / or pain, as well as other compounds correlated with pathophysiological processes associated with vertebral endplate degeneration or defects (e.g., premodic changes) or modic changes, such as intervertebral disc resorption, type III and type IV collagen degradation and formation, or myelofibrosis) may be obtained from the patient (e.g., by blood (e.g., serum) or by cerebrospinal fluid samples) to determine whether the patient is a candidate for vertebral nerve ablation (e.g., whether the patient has one or more candidate vertebrae exhibiting factors or symptoms associated with endplate degeneration or defects (e.g., premodic change characteristics)). Cytokine biomarker samples (e.g., pro-angiogenic serum cytokines such as vascular endothelial growth factor (VEGF)-C, VEGF-D, tyrosine-protein kinase receptor 2, VEGF receptor 1, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1) may be obtained from multiple different intervertebral discs, vertebral bodies, or intervertebral foramina of patients and compared to each other to determine which vertebral bodies are targeted for treatment. Other biomarkers such as neoepitopes of type III and type IV procollagen (e.g., PRO-C3, PRO-C4) and neoepitopes of type III and type IV collagen degradation (e.g., C3M, C4M) can also be evaluated.

[0111] In some implementations, samples are acquired over a period of time and compared to determine changes in levels over time. For example, biomarkers may be measured weekly, bimonthly, monthly, every three months, or every six months over a period of time and compared to analyze trends or changes over time. If significant changes are observed between biomarker levels (e.g., changes indicating endplate degeneration or defect (e.g., premodic change characteristics) or modic changes as described above), treatment may be recommended and implemented to prevent or treat back pain. Biomarker levels (e.g., substance P, cytokine protein levels, PRO-C3, PRO-C4, C3M, C4M levels) may be measured using a variety of in vivo or in vitro kits, systems, and techniques (e.g., radioimmunoassay kits / methods, enzyme-linked immunosorbent assay kits, immunohistochemistry techniques, array-based systems, bioassay kits, in vivo injection of anti-cytokine immunoglobulins, multiplex fluorescence microsphere immunoassays, homogeneous time-resolved fluorescence assays, bead-based techniques, interferometers, flow cytometry, etc.). Cytokine proteins can be measured directly or indirectly, for example, by measuring mRNA transcripts.

[0112] Identification of premodic alteration characteristics may involve a step of determining a quantitative or qualitative endplate score based on the severity, degree, and / or amount of the identified premodic alteration characteristics (e.g., vertebral endplate defects), and vertebrae with a quantitative endplate score above a threshold may be considered potential candidates for treatment (e.g., vertebral nerve ablation). Premodic alteration characteristics may be combined with other known risk factors such as age, sex, body mass index, bone mineral density measurements, history of back pain, and / or vertebral endplate degeneration or defect (e.g., smoking, occupational or recreational physical needs or circumstances) when identifying candidate patients and / or candidate vertebrae for treatment (e.g., vertebral nerve ablation).

[0113] conclusion In some implementations, the system comprises various features that exist as a single feature (as opposed to multiple features). For example, in one embodiment, the system includes a single radio frequency generator, a single introducer cannula with a single stylet, a single radio frequency energy delivery device or probe, and a single bipolar pair of electrodes. A single thermocouple (or other means for measuring temperature) may also be included. In alternative embodiments, multiple features or components are provided.

[0114] In some implementations, the system comprises one or more of the following: means for tissue modulation (e.g., ablation or other types of modulation catheters or delivery devices), means for monitoring temperature (e.g., thermocouples, thermistors, infrared sensors), means for imaging (e.g., MRI, CT, fluoroscopy), means for access (e.g., introducer assemblies, curved cannulas, drills, curettes), etc.

[0115] While specific embodiments and examples are described herein, the aspects of methods and devices shown and described herein may be combined and / or modified in different ways to form yet another embodiment. Furthermore, the methods described herein can be carried out using any device suitable for performing the enumerated steps. In addition, any specific features, aspects, methods, characteristics, features, qualities, attributes, elements, etc., disclosed herein (including figures) relating to various embodiments may be used in all other embodiments described herein. Section headings used herein are provided solely for readability and are not intended to limit the scope of embodiments disclosed in a particular section to the features or elements disclosed in that section.

[0116] While embodiments may accept various modifications and alternative forms, specific examples are shown in the drawings and described in detail herein. However, it should be understood that embodiments are not limited to any particular form or method disclosed, but rather encompass all modifications, equivalents, and alternatives that fall within the spirit and scope of the various embodiments and appended claims described herein. Any method disclosed herein does not need to be performed in the order listed. Methods disclosed herein include certain actions performed by the practitioner, but they may also include any third-party instructions, either express or implicit, for those actions. For example, an action such as "applying thermal energy" may include "ordering the application of thermal energy."

[0117] The terms “top,” “bottom,” “first,” “second,” “upper,” “lower,” “height,” “width,” “length,” “end,” “side,” “horizontal,” “vertical,” and similar terms may be used herein. It should be understood that these terms are used only to refer to structures shown in the figures and to facilitate the description of embodiments of this disclosure. The terms “proximal” and “distal” are terms of opposite directions. For example, the distal end of a device or component is the end of the component furthest from the operator during normal use. The distal end or tip does not necessarily mean the most distal end. The proximal end refers to the opposite end, i.e., the end closest to the operator during normal use. Various embodiments of this disclosure are presented in range form. It should be understood that the range form is merely for convenience and brevity and should not be interpreted as an inflexible limitation to the scope of the invention. The scope disclosed herein includes any and all overlaps, sub-scopes, and combinations thereof, as well as individual numerical values ​​within that scope. For example, a description of a range such as 70–115 degrees should be considered to specifically disclose subranges such as 70–80 degrees, 70–100 degrees, 70–110 degrees, 80–100 degrees, and individual numbers within those ranges, such as 70, 80, 90, 95, 100, 70.5, 90.5, and any whole and partial increments between them. Words such as “up to,” “at least,” “greater than,” “less than,” and “between” include the listed numbers. Numbers preceded by terms such as “about” or “approximately” include the listed numbers. For example, “about 2:1” includes “2:1.” For example, the terms “approximately,” “about,” and “substantially” as used herein refer to quantities close to the stated quantity that still perform the desired function or achieve the desired result.

Claims

1. A medical device for forming channels in bone, wherein the medical device is: An induction cannula having a hypotube arranged longitudinally, wherein the distal hypotube has an induction lumen through which it is positioned, A curved cannula having a long tube, wherein the long tube has a curved cannula lumen through which it is positioned, the long tube has a proximal straight tube portion and a distal curved tube portion, and the long tube is configured to be received in the lumen of the introduction cannula, A stylet having an elongated shaft, wherein the elongated shaft has a proximal straight portion and a distal curved portion, and the elongated shaft is configured to be received within the lumen of the curved cannula, Equipped with, A medical device wherein the distal curved portion of the stylet is configured to be pulled back from the curved cannula when the stylet is received in the lumen of the curved cannula.

2. The device according to claim 1, wherein the distal curved portion of the stylet has a section of reduced thickness.

3. The device according to claim 2, wherein the section with reduced thickness is 40% to 80% of the total thickness of the long shaft.

4. The device according to claim 2 or 3, wherein the section with reduced thickness is formed by removing material from at least one region of the distal curved portion.

5. The device according to any one of claims 1 to 4, wherein the distal curved portion has a rounded or inclined transition section between the reduced-thickness section and the distal channeling tip.

6. The device according to claim 2 or 3, wherein the section with reduced thickness is not uniform from the proximal end to the distal end of the distal curved portion.

7. The device according to claim 6, wherein the reduced thickness is tapered from the proximal end to the distal end of the distal curved portion.

8. The device according to claim 6 or 7, wherein the reduced thickness is tapered from the distal end to the proximal end of the distal curved portion.

9. The device according to claim 1, wherein the distal curved portion of the stylet has a slit formed along the length direction of the long shaft, and the slit separates the flexible curved section on the outer curved side of the distal curved portion from the flexible extension on the inner curved side of the distal curved portion.

10. The device according to claim 9, wherein the flexible extension extends along a portion of the length of the flexible curved section.

11. The device according to claim 9 or 10, wherein the flexible extension extends along the entire length of the flexible curved section.

12. The device according to claim 1, wherein the distal curved portion of the stylet has a plurality of slots formed perpendicular to the longitudinal direction of the long shaft on the outer curved side of the distal curved portion.

13. The device according to claim 12, wherein a notch is formed in the outer curvature of the distal curvature at the proximal end of the distal curvature.

14. The device according to any one of claims 1 to 13, wherein the distal opening tip of the curved cannula is a beveled tip.

15. The device according to claim 1, wherein the distal curved tube portion is configured to be flexible and elastic.

16. A medical device for forming channels in bone, wherein the medical device is: An induction cannula having a hypotube arranged longitudinally, wherein the distal hypotube has an induction lumen through which it is positioned, A curved cannula having a long tube, wherein the long tube has a curved cannula lumen through which it is positioned, the long tube has a proximal straight tube portion and a distal curved tube portion, and the long tube is configured to be received in the lumen of the introduction cannula, A stylet having an elongated shaft, wherein the elongated shaft has a proximal straight portion and a distal curved portion, and the elongated shaft is configured to be received within the lumen of the curved cannula, Equipped with, A medical device in which the distal curved portion of the stylet is freed from the substantially cylindrical shape of the stylet.

17. The device according to claim 16, wherein the distal curved portion of the stylet has a plurality of slots formed perpendicular to the longitudinal direction of the long shaft on the outer curved side of the distal curved portion.

18. The device according to claim 16, wherein the distal curved portion of the stylet has a section of reduced thickness.

19. The device according to claim 18, wherein the reduced-thickness section is 40% to 80% of the total circumference thickness of the elongated shaft.

20. The device according to claim 18, wherein the section with reduced thickness is formed by removing material from at least one region of the distal curved portion.

21. The device according to claim 18, wherein the distal curved portion has a rounded or inclined transition section between the reduced-thickness section and the distal channeling tip.

22. The device according to claim 18, wherein the section with reduced thickness is not uniform from the proximal end to the distal end of the distal curved portion.

23. The device according to claim 22, wherein the reduced thickness is tapered from the proximal end to the distal end of the distal curved portion.

24. The device according to claim 22, wherein the reduced thickness is tapered from the distal end to the proximal end of the distal curved portion.

25. The device according to claim 16, wherein the distal curved portion of the stylet has a slit formed along the length direction of the long shaft, and the slit separates the flexible curved section on the outer curved side of the distal curved portion from the flexible extension on the inner curved side of the distal curved portion.

26. The device according to claim 25, wherein the flexible extension extends along a portion of the length of the flexible curved section.

27. The device according to claim 25, wherein the flexible extension extends along the entire length of the flexible curved section.

28. The device according to claim 27, wherein a notch is formed in the outer curvature of the distal curvature at the proximal end of the distal curvature.

29. The device according to claim 16, wherein the open end of the curved cannula is a beveled end.

30. A medical device for accessing and treating tissue within a vertebral body, wherein the medical device is: An introduction cannula having an introduction lumen through which it is positioned, A curved cannula having a proximal straight tube portion and a distal curved tube portion, wherein the long tube is configured to be received in the lumen of the introduction cannula, A stylet having an elongated shaft, wherein the elongated shaft has a proximal straight portion and a distal curved portion, and the elongated shaft is configured to be received within the lumen of the curved cannula, A radio frequency probe, configured to be advanced through the lumen of the curved cannula to the target treatment site, A radio frequency energy generator connected to the radio frequency probe and configured to provide radio frequency energy to the radio frequency probe for treating the tissue, Equipped with, A medical device in which the distal curved portion of the stylet is freed from the substantially cylindrical shape of the stylet.

31. The device according to claim 30, wherein the radio frequency probe is a flexible bipolar probe.

32. The device according to claim 30, wherein the distal curved portion of the stylet has a plurality of slots formed perpendicular to the longitudinal direction of the long shaft on the outer curved side of the distal curved portion.

33. The device according to claim 30, wherein the open end of the curved cannula is a beveled tip.

34. A medical device for forming channels in bone, wherein the medical device is: An induction cannula having a hypotube arranged longitudinally, wherein the distal hypotube has an induction lumen through which it is positioned, A curved cannula having a long tube, wherein the long tube has a curved cannula lumen through which it is positioned, the long tube has a proximal straight tube portion and a distal curved tube portion, and the long tube is configured to be received in the lumen of the introduction cannula, A stylet having an elongated shaft, wherein the elongated shaft has a proximal straight portion and a distal curved portion, and the elongated shaft is configured to be received within the lumen of the curved cannula, Equipped with, A medical device wherein the distal curved portion of the stylet has a plurality of slots formed perpendicular to the longitudinal direction of the long shaft.

35. The device according to claim 34, wherein the plurality of slots are located on the outer curved side of the distal curved portion.

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