Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Application No. 61/329,220, filed on Apr. 29, 2010, which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to medical instruments and systems for creating a path or cavity in vertebral bone to receive bone cement to treat a vertebral compression fracture. The features relating to the methods and devices described herein can be applied in any region of bone or hard tissue where the tissue or bone is displaced to define a bore or cavity instead of being extracted from the body such as during a drilling or ablation procedure. In addition, the present invention also discloses methods and devices for ablating or coagulating tissues, including but not limited to ablating tumor tissue in vertebral and/or cortical bone. 
       SUMMARY OF THE INVENTION 
       [0003]    Methods and devices described herein relate to improved creation of a cavity within bone or other hard tissue where the cavity is created by displacement of the tissue. In a first example, a method according to the present disclosure includes treating a vertebral body or other bone structure. In one variation, the method includes providing an elongate tool having a sharp tip configured for penetration into vertebral bone, the tool having an axis extending from a proximal end to a working end thereof, where the working end comprises at least a first sleeve concentrically located within a second sleeve and a third sleeve located concentrically about the second sleeve, where each sleeve comprises a series of slots or notches to limit deflection of the working end to a first curved configuration in a single plane and where the respective series of slots or notches are radially offset in each sleeve; advancing the working end through vertebral bone; causing the working end to move from a linear configuration to a curved configuration by translating the first sleeve relative to the second sleeve in an axial direction; and moving the working end in the curved configuration within the bone to create a cavity therein. Translating of the first sleeve relative to the second sleeve can include moving either sleeve or both sleeves in an axial direction. Additional variations include moving one or both sleeves in a rotational direction to produce relative axial displacement between sleeves. 
         [0004]    In an additional variation, the present devices include medical osteotome devices that can for treat a hard tissue (e.g., in a vertebral body) by mechanically displacing the hard tissue and/or applying therapeutic energy to ablate or coagulate tissue. For example, one such variation includes an osteotome type device that is coupled to a power supply and further includes a handle having an actuating portion and a connector for electrically coupling the osteotome device to the power supply; a shaft comprising a first sleeve located concentrically within a second sleeve, the shaft having a distal portion comprising a working end capable of moving between a linear configuration and an articulated configuration where the articulated configuration is limited to a single plane, and where each sleeve comprises a series of slots or notches to limit deflection of the working end to the articulated configuration, where the respective series of slots or notches are radially offset in adjacent sleeves, where a first conductive portion of the shaft is electrically coupleable to a first pole of the power supply; a sharp tip located at a distal tip of the first sleeve of the working end, the sharp tip adapted to penetrate bone within the vertebral body, where the distal tip is coupleable to a second pole of the power supply, such that when activated, current flows between a portion of the distal tip and the shaft; a non-conductive layer electrically isolating the first sleeve from the first conductive portion; and where the shaft and sharp tip have sufficient column strength such that application of an impact force on the handle causes the distal portion of the shaft and the distal tip to mechanically displace the hard tissue. The power supply can be coupled to the outer sleeve (either the second or third sleeve discussed herein.) 
         [0005]    Another variations of the method disclosed herein can include the application of energy between electrodes on the device to ablate tissues (e.g., tumor) or to perform other electrosurgical or mapping procedures within the tissue. In one such example for treating a vertebral body, the method can include providing an elongate tool having a sharp tip configured for penetration into vertebral bone, the tool having an axis extending from a proximal end to a working end thereof, where the working end comprises at least a first sleeve concentrically located within a second sleeve, where each sleeve comprises a series of slots or notches to limit deflection of the working end to a first curved configuration in a single plane and where the respective series of slots or notches are radially offset in adjacent sleeves, where a first conductive portion of the first sleeve is electrically coupled to a first pole of a power supply; advancing the working end through vertebral bone; causing the working end to move from a linear configuration to a curved configuration by translating the first sleeve relative to the second sleeve in an axial direction; and applying energy between the first conductive portion and a return electrode electrically coupled to a second pole of the energy supply to ablate or coagulate a region within the vertebral body. 
         [0006]    In variations of the method, moving the working end to from the linear configuration to the curved configuration can include moving the working end to move through a plurality of curved configurations. 
         [0007]    In an additional variation, causing the working end to move from a linear configuration to the curved configuration comprises actuating a handle mechanism to move the working end from the linear configuration to the curved configuration. The handle mechanism can be moved axially and/or rotationally as described herein. 
         [0008]    In one variation, actuating of the handle mechanism causes the working end to move to the first curved configuration without torquing the third sleeve. 
         [0009]    In additional variations, the working end of the osteotome or tool is spring biased to assume the linear configuration. 
         [0010]    The working end can move from the linear configuration to the curved configuration by applying a driving force or impact to the elongate tool wherein penetration in the cortical bone moves the working end from the linear configuration to the curved configuration. For example, as a hammering or impact force is applied to the working end, the interaction of the sharp tip against bone causes the working end to assume an articulated and/or curved configuration. Where further axial movement of the tool causes compression of the bone and creation of the cavity. 
         [0011]    The method can further include the use of one or more cannulae to introduce the tool into the target region. Such a cannula can maintain the tool in a straight or linear configuration until the tool advances out of the cannula or until the cannula is withdrawn from over the tool. 
         [0012]    As described herein, upon creation of the cavity, the method can further include the insertion of a filler material or other substance into the cavity. The filler material can be delivered through the tool or through a separate cannula or catheter. 
         [0013]    This disclosure also includes variations of devices for creating a cavity within bone or hard tissue. Such variations include devices for treating a vertebral body or other such structure. In one variation a device includes a handle having an actuating portion; a shaft comprising a first sleeve located concentrically within a second sleeve and a third sleeve located concentrically about the second sleeve, the shaft having a distal portion comprising a working end capable of moving between a linear configuration and an articulated configuration where the second articulated configuration is limited to a single plane, and where each sleeve comprises a series of slots or notches to limit deflection of the working end to the articulated configuration, where the respective series of slots or notches are radially offset in each sleeve; and a sharp tip located at a distal tip of the working end, the sharp tip adapted to penetrate vertebral bone within the vertebral body. 
         [0014]    In one variation, the devices described herein can include a configuration where the first sleeve is affixed to the second sleeve at the working end such that proximal movement of the first sleeve causes the working end to assume the articulated configuration. The sleeves can be affixed at any portion along their length via a mechanical fixation means (e.g., a pin or other fixation means), an adhesive, or one or more weld points. In some variations, fixation of the sleeves occurs at the working end so that movement of the inner or first sleeve causes the working end to assume the curved configuration. In some cases, the third sleeve can be affixed outside of the working end so long as when the first and second sleeves articulate, the third sleeve still articulates. 
         [0015]    Devices described herein can optionally include a force-limiting assembly coupled between the actuating portion and the first sleeve such that upon reaching a threshold force, the actuating portion disengages the first sleeve. In one variation, the force-limiting mechanism is adapted to limit force applied to bone when moving the working end from the first configuration toward the second configuration. 
         [0016]    In additional variations, devices for creating cavities in bone or hard tissue can include one or more spring elements that extending through the first sleeve, where the spring element is affixed to the shaft (within or about either the first, second, or third sleeve). Such spring elements cause the working end to assume a linear configuration in a relaxed state. 
         [0017]    In additional variations, a device can include an outer or third sleeve where the slots or notches (that allow deflection) are located on an exterior surface of the third sleeve. The exterior surface is typically the surface that faces outward from a direction of the curved configuration. This configuration allows for an interior surface (the surface located on the interior of the curved portion) to be smooth. As a result, if the device is withdrawn through tissue or a cannula or other introducer, the smooth surface on the interior of the curve minimizes the chance that the device becomes caught on the opening of the cannula or any other structure. 
         [0018]    Variations of the device can include one or more lumens that extend through the shaft and working end. These lumens can exit at a distal tip of the device or through a side opening in a wall of the device. The lumen can include a surface comprising a lubricious polymeric material. For example, the material can comprise any bio-compatible material having low frictional properties (e.g., TEFLON®, a polytetrafluroethylene (PTFE), FEP (Fluorinated ethylenepropylene), polyethylene, polyamide, ECTFE (Ethylenechlorotrifluoro-ethylene), ETFE, PVDF, polyvinyl chloride and silicone). 
         [0019]    As described herein, the devices can include any number of configurations to prevent rotation between adjacent sleeves but allow axial movement between the sleeves. For example, the sleeves can be mechanically coupled via a pin/slot or key/keyway configuration. In an additional variation, the sleeves can be non-circular to prevent rotation. 
         [0020]    In an additional variation, the disclosure includes various kits comprising the device described herein as well as a filler material (e.g., a bone cement or other bone filler material). 
         [0021]    Variations of the access device and procedures described above include combinations of features of the various embodiments or combination of the embodiments themselves wherever possible. 
         [0022]    The methods, devices and systems described herein can be combined with the following commonly assigned patent applications and provisional applications, the entirety of each of which is incorporated by reference herein: Application No. 61/194,766, filed Sep. 30, 2008; Application No. 61/104,380, filed Oct. 10, 2008; Application No. 61/322,281, filed Apr. 8, 2010; application Ser. No. 12/571,174 filed Sep. 30, 2009; PCT Application number PCT/US2009/059113 filed Sep. 30, 2009; application Ser. No. 12/578,455 filed Oct. 13, 2009. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0023]      FIG. 1  is a plan view of an osteotome of the invention. 
           [0024]      FIG. 2  is a side view of the osteotome of  FIG. 1 . 
           [0025]      FIG. 3  is a cross sectional view of the osteotome of  FIG. 1 . 
           [0026]      FIG. 4  is an enlarged sectional view of the handle of the osteotome of  FIG. 1 . 
           [0027]      FIG. 5  is an enlarged sectional view of the working end of the osteotome of  FIG. 1 . 
           [0028]      FIG. 6A  is a sectional view of the working end of  FIG. 5  in a linear configuration. 
           [0029]      FIG. 6B  is a sectional view of the working end of  FIG. 5  in a curved configuration. 
           [0030]      FIGS. 7A-7C  are schematic sectional views of a method of use of the osteotome of  FIG. 1 . 
           [0031]      FIG. 8  is another embodiment of an osteotome working end. 
           [0032]      FIG. 9  is another embodiment of an osteotome working end. 
           [0033]      FIG. 10  is another variation of an osteotome with an outer sleeve. 
           [0034]      FIG. 11  is a cut-away view of the working end of the osteotome of  FIG. 10 . 
           [0035]      FIG. 12A  is sectional view of another embodiment of working end, taken along line  12 A- 12 A of  FIG. 11 . 
           [0036]      FIGS. 12B and 12C  illustrate additional variations of preventing rotation between adjacent sleeves. 
           [0037]      FIG. 13  is sectional view of another working end embodiment similar to that of  FIG. 11 . 
           [0038]      FIG. 14  is a cut-away perspective view of the working end of  FIG. 13 . 
           [0039]      FIG. 15  illustrates a variation of an osteotome as described herein having electrodes on a tip of the device and another electrode on the shaft. 
           [0040]      FIG. 16  illustrates an osteotome device as shown in  FIG. 15  after being advanced into the body and where current passes between electrodes. 
           [0041]      FIG. 17  illustrates a variation of a device as described herein further including a connector for providing energy at the working end of the device. 
           [0042]      FIGS. 18A and 18B  illustrate a device having a sharp tip as disclosed herein where the sharp tip is advanceable from the distal end of the shaft. 
           [0043]      FIG. 19  shows a cross sectional view of the device illustrated in  FIG. 18B  and also illustrates temperature sensing elements located on device. 
           [0044]      FIG. 20  shows a variation of a device where the inner sleeve is extended from the device and where current is applied between the extended portion of the inner sleeve and the shaft to treat tissue. 
           [0045]      FIG. 21  illustrates a variation of a device as described herein further including an extendable helical electrode carried by the working end of the device. 
           [0046]      FIGS. 22A and 22B  illustrate the device of  FIG. 21  with the helical electrode in a non-extended position and an extended position. 
           [0047]      FIGS. 22C and 22D  illustrate charts of variations of electrodes having ablated volumes given a particular duration of an ablation cycle. 
           [0048]      FIG. 23  illustrates the working end of the device of  FIG. 21  in a vertebral body with the helical electrode delivering Rf energy to tissue for ablation or other treatments. 
       
    
    
     DETAILED DESCRIPTION 
       [0049]    Referring to  FIGS. 1-5 , an apparatus or osteotome  100  is shown that is configured for accessing the interior of a vertebral body and for creating a pathway in vertebral cancellous bone to receive bone cement. In one embodiment, the apparatus is configured with an extension portion or member  105  for introducing through a pedicle and wherein a working end  110  of the extension member can be progressively actuated to curve a selected degree and/or rotated to create a curved pathway and cavity in the direction of the midline of the vertebral body. The apparatus can be withdrawn and bone fill material can be introduced through a bone cement injection cannula. Alternatively, the apparatus  100  itself can be used as a cement injector with the subsequent injection of cement through a lumen  112  of the apparatus. 
         [0050]    In one embodiment, the apparatus  100  comprises a handle  115  that is coupled to a proximal end of the extension member  105 . The extension member  105  comprises an assembly of first (outer) sleeve  120  and a second (inner) sleeve  122 , with the first sleeve  120  having a proximal end  124  and distal end  126 . The second sleeve  122  has a proximal end  134  and distal end  136 . The extension member  105  is coupled to the handle  115 , as will be described below, to allow a physician to drive the extension member  105  into bone while contemporaneously actuating the working end  110  into an actuated or curved configuration (see  FIG. 6 ). The handle  115  can be fabricated of a polymer, metal or any other material suitable to withstand hammering or impact forces used to drive the assembly into bone (e.g., via use of a hammer or similar device on the handle  115 ). The inner and outer sleeves are fabricated of a suitable metal alloy, such as stainless steel or NiTi. The wall thicknesses of the inner and outer sleeves can range from about 0.005″ to 0.010″ with the outer diameter the outer sleeve ranging from about 2.5 mm to 5.0 mm. 
         [0051]    Referring to  FIGS. 1 ,  3  and  4 , the handle  115  comprises both a first grip portion  140  and a second actuator portion indicated at  142 . The grip portion  140  is coupled to the first sleeve  120  as will be described below. The actuator portion  142  is operatively coupled to the second sleeve  122  as will be described below. The actuator portion  142  is rotatable relative to the grip portion  140  and one or more plastic flex tabs  145  of the grip portion  140  are configured to engage notches  146  in the rotatable actuator portion  142  to provide tactile indication and temporary locking of the handle portions  140  and  142  in a certain degree of rotation. The flex tabs  145  thus engage and disengage with the notches  146  to permit ratcheting (rotation and locking) of the handle portions and the respective sleeve coupled thereto. 
         [0052]    The notches or slots in any of the sleeves can comprise a uniform width along the length of the working end or can comprise a varying width. Alternatively, the width can be selected in certain areas to effectuate a particular curved profile. In other variation, the width can increase or decrease along the working end to create a curve having a varying radius. Clearly, it is understood that any number of variations are within the scope of this disclosure. 
         [0053]      FIG. 4  is a sectional view of the handle showing a mechanism for actuating the second inner sleeve  122  relative to the first outer sleeve  120 . The actuator portion  142  of the handle  115  is configured with a fast-lead helical groove indicated at  150  that cooperates with a protruding thread  149  of the grip portion  140  of the handle. Thus, it can be understood that rotation of the actuation portion  142  will move this portion to the position indicated at  150  (phantom view). In one embodiment, when the actuator portion  142  is rotated a selected amount from about 45° to 720°, or from about 90° to 360°, the inner sleeve  122  is lifted proximally relative to the grip portion  140  and outer sleeve  120  to actuate the working end  110 . As can be seen in  FIG. 4  the actuator portion  142  engages flange  152  that is welded to the proximal end  132  of inner sleeve  122 . The flange  152  is lifted by means of a ball bearing assembly  154  disposed between the flange  152  and metal bearing surface  155  inserted into the grip portion  140  of the handle. Thus, the rotation of actuator  142  can lift the inner sleeve  122  without creating torque on the inner sleeve. 
         [0054]    Now turning to  FIGS. 5 ,  6 A and  6 B, it can be seen that the working end  110  of the extension member  105  is articulated by cooperating slotted portions of the distal portions of outer sleeve  120  and inner sleeve  122  that are both thus capable of bending in a substantially tight radius. The outer sleeve  120  has a plurality of slots or notches  162  therein that can be any slots that are perpendicular or angled relative to the axis of the sleeve. The inner sleeve  122  has a plurality of slots or notches indicated at  164  that can be on an opposite side of the assembly relative to the slots  162  in the outer sleeve  120 . The outer and inner sleeves are welded together at the distal region indicated at weld  160 . It thus can be understood that when inner sleeve  122  is translated in the proximal direction, the outer sleeve will be flexed as depicted in  FIG. 6B . It can be understood that by rotating the actuator handle portion  142  a selected amount, the working end can be articulated to a selected degree. 
         [0055]      FIGS. 4 ,  5 ,  6 A and  6 B further illustrate another element of the apparatus that comprises a flexible flat wire member  170  with a proximal end  171  and flange  172  that is engages the proximal side of flange  152  of the inner sleeve  122 . At least the distal portion  174  of the flat wire member  170  is welded to the inner sleeve at weld  175 . This flat wire member thus provides a safety feature to retain the working end in the event that the inner sleeve fails at one of the slots  164 . 
         [0056]    Another safety feature of the apparatus comprises a torque limiter and release system that allows the entire handle assembly  115  to freely rotate—for example if the working end  110  is articulated, as in  FIG. 6B , when the physician rotates the handle and when the working end is engaged in strong cancellous bone. Referring to  FIG. 4 , the grip portion  142  of the handle  115  engages a collar  180  that is fixed to a proximal end  124  of the outer sleeve  120 . The collar  180  further comprises notches  185  that are radially spaced about the collar and are engaged by a ball member  186  that is pushed by a spring  188  into notches  185 . At a selected force, for example a torque ranging from greater than about 0.5 inch*lbs but less that about 7.5 inch*lbs, 5.0 inch*lbs or 2.5 inch*lbs, the rotation of the handle  115  overcomes the predetermined limit. When the torque limiter assembly is in its locked position, the ball bearing  186  is forced into one of the notches  185  in the collar  180 . When too much torque is provided to the handle and outer sleeve, the ball bearing  186  disengages the notch  185  allowing the collar  180  to turn, and then reengages at the next notch, releasing anywhere from 0.5 inch*lbs to 7.5 inch*lbs of torque. 
         [0057]    Referring to  FIGS. 6A and 6B , it can be understood that the inner sleeve  122  is weakened on one side at its distal portion so as to permit the inner sleeve  122  to bend in either direction but is limited by the location of the notches in the outer sleeve  120 . The curvature of any articulated configuration is controlled by the spacing of the notches as well as the distance between each notch peak. The inner sleeve  122  also has a beveled tip for entry through the cortical bone of a vertebral body. Either the inner sleeve or outer sleeve can form the distal tip. 
         [0058]    Referring to  FIGS. 7A-7C , in one variation of use of the device, a physician taps or otherwise drives a stylet  200  and introducer sleeve  205  into a vertebral body  206  typically until the stylet tip  208  is within the anterior ⅓ of the vertebral body toward cortical bone  210  ( FIG. 7A ). Thereafter, the stylet  200  is removed and the sleeve  205  is moved proximally ( FIG. 7B ). As can be seen in  FIG. 7B , the tool or osteotome  100  is inserted through the introducer sleeve  205  and articulated in a series of steps as described above. The working end  110  can be articulated intermittently while applying driving forces and optionally rotational forces to the handle  115  to advance the working end through the cancellous bone  212  to create path or cavity  215 . The tool is then tapped to further drive the working end  110  to, toward or past the midline of the vertebra. The physician can alternatively articulate the working end  110 , and drive and rotate the working end further until imaging shows that the working end  100  has created a cavity  215  of an optimal configuration. Thereafter, as depicted in  FIG. 7C , the physician reverses the sequence and progressively straightens the working end  110  as the extension member is withdrawn from the vertebral body  206 . Thereafter, the physician can insert a bone cement injector  220  into the path or cavity  215  created by osteotome  100 .  FIG. 7C  illustrates a bone cement  222 , for example a PMMA cement, being injected from a bone cement source  225 . 
         [0059]    In another embodiment (not shown), the apparatus  100  can have a handle  115  with a Luer fitting for coupling a bone cement syringe and the bone cement can be injected through the lumen  112  of the apparatus. In such an embodiment  FIG. 9 , the lumen can have a lubricious surface layer or polymeric lining  250  to insure least resistance to bone cement as it flows through the lumen. In one embodiment, the surface or lining  250  can be a fluorinated polymer such as TEFLON® or polytetrafluroethylene (PTFE). Other suitable fluoropolymer resins can be used such as FEP and PFA. Other materials also can be used such as FEP (Fluorinated ethylenepropylene), ECTFE (Ethylenechlorotrifluoro-ethylene), ETFE, Polyethylene, Polyamide, PVDF, Polyvinyl chloride and silicone. The scope of the invention can include providing a polymeric material having a static coefficient of friction of less than 0.5, less than 0.2 or less than 0.1. 
         [0060]      FIG. 9  also shows the extension member or shaft  105  can be configured with an exterior flexible sleeve indicated at  255 . The flexible sleeve can be any commonly known biocompatible material, for example, the sleeve can comprise any of the materials described in the preceding paragraph. 
         [0061]    As also can be seen in  FIG. 9 , in one variation of the device  100 , the working end  110  can be configured to deflect over a length indicated at  260  in a substantially smooth curve. The degree of articulation of the working end  100  can be at least 45°, 90°, 135° or at least 180° as indicated at  265  ( FIG. 9 ). In additional variations, the slots of the outer  120  and inner sleeves  120  can be varied to produce a device having a radius of curvature that varies among the length  260  of the device  100 . 
         [0062]    In another embodiment of the invention, the inner sleeve can be spring loaded relative the outer sleeve, in such a way as to allow the working end to straighten under a selected level of force when pulled in a linear direction. This feature allows the physician to withdraw the assembly from the vertebral body partly or completely without further rotation the actuating portion  142  of handle  115 . In some variations, the force-limiter can be provided to allow less than about 10 inch*lbs of force to be applied to bone. 
         [0063]    In another embodiment shown in  FIG. 8 , the working end  110  is configured with a tip  240  that deflects to the position indicated at  240 ′ when driven into bone. The tip  240  is coupled to the sleeve assembly by resilient member  242 , for example a flexible metal such as stainless steel or NiTi. It has been found that the flexing of the tip  240  causes its distal surface area to engage cancellous bone which can assist in deflecting the working end  110  as it is hammered into bone. 
         [0064]    In another embodiment of the invention (not shown), the actuator handle can include a secondary (or optional) mechanism for actuating the working end. The mechanism would include a hammer-able member with a ratchet such that each tap of the hammer would advance assembly and progressively actuate the working end into a curved configuration. A ratchet mechanism as known in the art would maintain the assembly in each of a plurality of articulated configurations. A release would be provided to allow for release of the ratchet to provide for straightening the extension member  105  for withdrawal from the vertebral body. 
         [0065]      FIGS. 10 and 11  illustrate another variation of a bone treatment device  400  with a handle  402  and extension member  405  extending to working end  410  having a similar construction to that  FIGS. 1 to 6B . The device  400  operates as described previously with notched first (outer) sleeve  120  and cooperating notched second (inner) sleeve  122 . However, the variation shown in  FIGS. 10 and 11  also includes a third concentric notched sleeve  420 , exterior to the first  120  and second  122  sleeves. The notches or slots in sleeve  420  at the working end  410  permit deflection of the sleeve as indicated at  265  in  FIG. 11 . 
         [0066]      FIG. 10  also illustrates the treatment device  400  as including a luer fitting  412  that allows the device  402  to be coupled to a source of a filler material (e.g., a bone filler or bone cement material). The luer can be removable from the handle  402  to allow application of an impact force on the handle as described above. Moreover, the luer fitting  402  can be located on the actuating portion of the handle, the stationary part of the handle or even along the sleeve. In any case, variations of the device  400  permit coupling the filler material with a lumen extending through the sleeves (or between adjacent sleeves) to deposit filler material at the working end  410 . As shown by arrows  416 , filler material can be deposited through a distal end of the sleeves (where the sharp tip is solid) or can be deposited through openings in a side-wall of the sleeves. Clearly, variations of this configuration are within the scope of those familiar in the field. 
         [0067]    In some variations, the third notched sleeve  420  is configured with its smooth (non-notched) surface  424  disposed to face inwardly on the articulated working end ( FIG. 11 ) such that a solid surface forms the interior of the curved portion of the working end  410 . The smooth surface  424  allows withdrawal of the device  110  into a cannula or introducer  205  without creating a risk that the slots or notches become caught on a cannula  205  (see e.g.,  FIG. 7B ). 
         [0068]    As shown in  FIGS. 10-11 , the third (outermost) sleeve  420  can extend from an intermediate location on the extension member  405  to a distal end of the working end  410 . However, variations of the device include the third sleeve  420  extending to the handle  402 . However, the third sleeve  420  is typically not coupled to the handle  402  so that any rotational force or torque generated by the handle  402  is not directly transmitted to the third sleeve  420 . 
         [0069]    In one variation, the third sleeve  420  is coupled to the second sleeve  120  at only one axial location. In the illustrated example shown in  FIG. 11 , the third sleeve  420  is affixed to second sleeve  420  by welds  428  at the distal end of the working end  410 . However, the welds or other attachment means (e.g., a pin, key/keyway, protrusion, etc.) can be located on a medial part of the sleeve  420 . The sleeve  420  can be fabricated of any bio-compatible material. For example, in one variation, the third sleeve is fabricated form a 3.00 mm diameter stainless steel material with a wall thickness of 0.007″. The first, second and third sleeves are sized to have dimensions to allow a sliding fit between the sleeves. 
         [0070]      FIG. 12A  is a sectional view of extension member  405  of another variation, similar to that shown in  FIGS. 10-11 . However, the variation depicted by  FIG. 12A  comprises non-round configurations of concentric slidable sleeves (double or triple sleeve devices). This configuration limits or prevents rotation between the sleeves and allows the physician to apply greater forces to the bone to create a cavity. While  FIG. 12A  illustrates an oval configuration, any non-round shape is within the scope of this disclosure. For example, the cross-sectional shape can comprise a square, polygonal, or other radially keyed configuration as shown in  FIGS. 12B and 12C . As shown in  FIG. 12C  the sleeves can include a key  407  and a receiving keyway  409  to prevent rotation but allow relative or axial sliding of the sleeves. The key can comprise any protrusion or member that slides within a receiving keyway. Furthermore, the key can comprise a pin or any raised protrusion on an exterior or interior of a respective sleeve. In this illustration, only the first  122  and second  120  sleeves are illustrated. However, any of the sleeves can be configured with the key/keyway. Preventing rotation between sleeves improves the ability to apply force to bone at the articulated working end. 
         [0071]      FIGS. 13-14  illustrate another variation of a working end  410  of an osteotome device. 
         [0072]    In this variation, the working end  410  includes one or more flat spring elements  450 ,  460   a ,  460   b ,  460   c ,  460   d , that prevent relative rotation of the sleeves of the assembly thus allowing greater rotational forces to be applied to cancellous bone from an articulated working end. The spring elements further urge the working end assembly into a linear configuration. To articulate the sleeves, a rotational force is applied to the handle as described above, once this rotational force is removed, the spring elements urge the working end into a linear configuration. As shown in  FIG. 13 , one or more of the spring elements can extend through the sleeves for affixing to a handle to prevent rotation. Furthermore, the distal end  454  of flat spring element  450  is fixed to sleeve assembly by weld  455 . Thus, the spring element is fixed at each end to prevent its rotation. Alternate variations include one or more spring elements being affixed to the inner sleeve assembly at a medial section of the sleeve. 
         [0073]    As shown in  FIGS. 13-14 , variations of the osteotome can include any number of spring elements  460   a - 460   d . These additional spring elements  460   a - 460   d  can be welded at either a proximal or distal end thereof to an adjacent element or a sleeve to allow the element to function as a leaf spring. 
         [0074]    In an additional variation, the osteotome device can include one or more electrodes  310 ,  312  as shown in  FIG. 15 . In this particular example, the device  300  includes spaced apart electrodes having opposite polarity to function in a bi-polar manner. However, the device can include a monopolar configuration. Furthermore, one or more electrodes can be coupled to individual channels of a power supply so that the electrodes can be energized as needed. Any variation of the device described above can be configured with one or more electrodes as described herein. 
         [0075]      FIG. 16  illustrates an osteotome device  300  after being advanced into the body as discussed above. As shown by lines  315  representing current flow between electrodes, when required, the physician can conduct RF current between electrodes  310  and  312  to apply coagulative or ablative energy within the bone structure of the vertebral body (or other hard tissue). While  FIG. 16  illustrates RF current  315  flow between electrodes  310  and  312 , variations of the device can include a number of electrodes along the device to apply the proper therapeutic energy. Furthermore, an electrode can be spaced from the end of the osteotome rather than being placed on the sharp tip as shown by electrode  310 . In some variations, the power supply is coupled to the inner sharp tip or other working end of the first sleeve. In those variations with only two sleeves, the second pole of the power supply is coupled with the second sleeve (that is the exterior of the device) to form a return electrode. However, in those variations having three sleeves, the power supply can alternatively be coupled with the third outer sleeve. In yet additional variations, the second and third sleeves can both function as return electrodes. However, in those devices that are monopolar, the return electrode will be placed outside of the body on a large area of skin 
         [0076]      FIGS. 17 to 20  illustrate another variation of an articulating probe or osteotome device  500 . In this variation, the device  500  includes a working end  505  that carries one or more RF electrodes that can be used to conduct current therethrough. Accordingly, the device can be used to sense impedance of tissue, locate nerves, or simply apply electrosurgical energy to tissue to coagulate or ablate tissue. In one potential use, the device  500  can apply ablative energy to a tumor or other tissue within the vertebra as well as create a cavity. 
         [0077]      FIGS. 17 ,  18 A,  18 B and  19 , illustrate a variation of the device  500  as having a handle portion  506  coupled to a shaft assembly  510  that extends along axis  512  to the articulating working end  505 . The articulating working end  505  can be actuatable as described above. In addition,  FIG. 17  shows that handle component  514   a  can be rotated relative to handle component  514   b  to cause relative axial movement between a first outer sleeve  520  and second inner sleeve  522  ( FIG. 19 ) to cause the slotted working ends of the sleeve assembly to articulate as described above. The working end  505  of  FIG. 19  shows two sleeves  520  and  522  that are actuatable to articulate the working end, but it should be appreciated that a third outer articulating sleeve can be added as depicted above. In one variation, the articulating working end can articulate 90° by rotating handle component  514   a  between ¼ turn and ¾ turn. The rotating handle component  514   a  can include detents at various rotational positions to allow for controlled hammering of the working end into bone. For example, the detents can be located at every 45° rotation or can be located at any other rotational increment. 
         [0078]      FIG. 17  depict an RF generator  530 A and RF controller  530 B connectable to an electrical connector  532  in the handle component  514   a  with a plug connector indicated at  536 . The RF generator is of the type known in the art for electrosurgical ablation. The outer sleeve  520  comprises a first polarity electrode indicated at  540 A (+). However, any energy modality can be employed with the device. 
         [0079]      FIGS. 18A and 18B  illustrate yet another variation of a working end of a device for creating cavities in hard tissue. As shown, the device  500  can include a central extendable sleeve  550  with a sharp tip  552  that is axially extendable from passageway  554  of the assembly of first and second sleeves  520  and  522  ( FIG. 19 ). The sleeve  550  can also include a second polarity electrode indicated at  540 B (−). Clearly, the first and second electrodes will be electrically insulated from one another. In one variation, and as shown in  FIG. 19 , the sleeve assembly can carry a thin sleeve  555  or coating of an insulative polymer such as PEEK to electrically isolate the first polarity electrode  540 A (+) from the second polarity electrode  540 B (−). The electrode can be deployed by rotating knob  558  on the striking surface of handle component  514   a  ( FIG. 17 ). The degree of extension of central sleeve  550  can optionally be indicated by a slider tab  557  on the handle. In the illustrated variation, the slider tab is located on either side of handle component  514   a  ( FIG. 17 ). Sleeve  550  can be configured to extend distally beyond the assembly of sleeves  520  and  522  a distance of about 5 to 15 mm. 
         [0080]    Referring to  FIG. 19 , the central extendable sleeve  550  can have a series of slots in at least a distal portion thereof to allow it to bend in cooperation with the assembly of first and second sleeves  520  and  522 . In the embodiment shown in  FIG. 18B , the central sleeve  550  can optionally include a distal portion that does not contain any slots. However, additional variations include slots on the distal portion of the sleeve. 
         [0081]      FIG. 19  further depicts an electrically insulative collar  560  that extends length A to axially space apart the first polarity electrode  540 A (+) from the second polarity electrode  540 B (−). The axial length A can be from about 0.5 to 10 mm, and usually is from 1 to 5 mm. The collar can be a ceramic or temperature resistant polymer. 
         [0082]      FIG. 19  also depicts a polymer sleeve  565  that extends through the lumen in the center of electrode sleeve  550 . The polymer sleeve  565  can provide saline infusion or other fluids to the working end and/or be used to aspirate from the working end when in use. The distal portion of sleeve  550  can include one or more ports  566  therein for delivering fluid or aspirating from the site. 
         [0083]    In all other respects, the osteotome system  500  can be driven into bone and articulated as described above. The electrodes  540 A and  540 B are operatively coupled to a radiofrequency generator as is known in the art for applying coagulative or ablative electrosurgical energy to tissue. In  FIG. 20 , it can be seen that RF current  575  is indicated in paths between electrodes  540 A and  540 B as shown by lines  575 . RF generator  530 A and controller  530 B for use with the devices described herein can include any number of power settings to control the size of targeted coagulation or ablation area. For example, the RF generator and controller can have Low (5 watts), medium (15 Watts) and High (25 watts) power settings. The controller  530 B can have a control algorithm that monitors the temperature of the electrodes and changes the power input in order to maintain a constant temperature. At least one temperature sensing element (e.g., a thermocouple) can be provided on various portions of the device. For example, and as shown in  FIG. 19 , a temperature sensing element  577  can be provided at the distal tip of sleeve  550  tip while a second temperature sensing element  578  can be provided proximal from the distal tip to provide temperature feedback to the operator to indicate the region of ablated tissue during the application of RF energy. In one example, the second temperature sensing element was located approximately 15 to 20 mm from the distal tip. 
         [0084]      FIG. 21  illustrates another variation of articulating osteotome  600  with RF ablation features. Variations of the illustrated osteotome  600  can be similar to the osteotome of  FIGS. 17-18B . In this variation, the osteotome  600  has a handle  602  coupled to shaft assembly  610  as described above. The working end  610  again has an extendable assembly indicated at  615  in  FIG. 21  that can be extended by rotation of handle portion  622  relative to handle  602 . The osteotome can be articulated as described previously by rotating handle portion  620  relative to handle  602 . 
         [0085]      FIGS. 22A-22B  are views of the working end  610  of  FIG. 21  in a first non-extended configuration ( FIG. 22A ) and a second extended configuration ( FIG. 22B ). As can be seen in  FIGS. 22A-22B , the extension portion  615  comprises an axial shaft  624  together with a helical spring element  625  that is axially collapsible and extendible. In one embodiment, the shaft can be a tube member with ports  626  fluidly coupled to a lumen  628  therein. In some variations, the ports can carry a fluid to the working end or can aspirate fluid from the working end. 
         [0086]    In  FIGS. 22A-22B , it can be seen that axial shaft  624 , helical spring element  625  together with sharp tip  630  comprise a first polarity electrode (+) coupled to electrical source  530 A and controller  530 B as described previously. An insulator  632  separates the helical spring  625  electrode from the more proximal portion of the sleeve which comprises opposing polarity electrode  640  (−). The RF electrodes can function as described above (see  FIG. 20 ) to ablate tissue or otherwise deliver energy to tissue. 
         [0087]    In one variation, the extension portion  615  can extend from a collapsed spring length of 2 mm, 3 mm, 4 mm or 5 mm to an extended spring length of 6 mm, 7 mm, 8 mm, 9 mm 10 mm or more. In the working end embodiment  615  in  FIG. 22B , the spring can comprise a flat rectangular wire that assists in centering the spring  625  about shaft  624  but still can collapse to short overall length, with the flat surfaces of rectangular wire oriented for stacking. However, other variations are within the scope of the variations described herein. 
         [0088]    The use of the spring  625  as an electrode provides significant improvements in delivering energy. This spring provides (i) greatly increased electrode surface area and (ii) a very greatly increased length of relatively sharp edges provided by the rectangular wire—which provides for edges. Because the edges provide low surface area the concentration or density of RF current is greater at the edges and allows for theh RF current to jump or arc. Both these aspects of the invention—increased electrode surface area and increased electrode edge length—allow for much more rapid tissue ablation. 
         [0089]    In one aspect of the invention, the surface area of the spring electrode  625  can be at least 40 mm 2 , at least 50 mm 2 , or at least 60 mm 2  over the spring electrode lengths described above. 
         [0090]    In another aspect of the invention, the total length of the 4 edges of rectangular wire spring can be greater than 50 mm, greater than 100 mm or greater than 150 mm over the spring electrode lengths described above. 
         [0091]    In one example used in testing, an osteotome  600  (as in  FIG. 21-22B ) was configured with a helical spring that had a collapsed length of 1.8 mm and an extended length of 7.5 mm. In this embodiment, the surface area of the spring electrode  625  when extended was 64.24 mm 2  and the total length of the electrodes edges was 171.52 mm (four edges at 42.88 mm per edge). 
         [0092]    In a comparison test, a first osteotome without a helical electrode was compared against a second osteotome  600  with a helical electrode as in  FIG. 22B . These devices were evaluated at different power levels and different energy delivery intervals to determine volume of ablation. The working ends of the devices had similar dimensions excepting for the helical spring electrode. Referring to  FIG. 22C , RF energy was delivered at a low power setting of 5 Watts. It can be seen in  FIG. 22C  that at a treatment interval of 120 seconds and 5 W, the volume of ablation was about 3 times faster with the helical electrode compared to the working end without the helical electrode (1.29 cc vs. 0.44 cc). 
         [0093]    Another comparison test of the same first osteotome  500  ( FIG. 18B ) and second osteotome  600  with a helical electrode ( FIG. 22B ) were evaluated at higher 15 Watt power level. As can be seen in  FIG. 22D , RF energy at a treatment interval of 25 seconds and 15 W, the volume of ablation was again was about 3 times faster with the helical electrode compared to the working end without the helical electrode (1.00 cc vs. 0.37 cc). Referring to  FIG. 22D , the device without the helical electrode impeded out before 60 seconds passed, so that data was not provided. The testing shows that the helical electrode is well suited for any type of tissue or tumor ablation, with a 60 second ablation resulting in 1.63 cc of ablated tissue. 
         [0094]      FIG. 23  schematically illustrates the osteotome  600  in use in a vertebral body, wherein the RF current between the electrodes  625  and  640  ablate a tissue volume indicated at  640 . 
         [0095]    Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration and the above description of the invention is not exhaustive. Specific features of the invention are shown in some drawings and not in others, and this is for convenience only and any feature may be combined with another in accordance with the invention. A number of variations and alternatives will be apparent to one having ordinary skills in the art. Such alternatives and variations are intended to be included within the scope of the claims. Particular features that are presented in dependent claims can be combined and fall within the scope of the invention. The invention also encompasses embodiments as if dependent claims were alternatively written in a multiple dependent claim format with reference to other independent claims.

Technology Category: 1