Arthroscopic devices and methods

Abstract

To provide arthroscopic devices and methods, specifically, to provide a tissue resecting device configured to execute both of mechanical cutting an electrosurgical cutting, resection and blood coagulation procedure, and tissue resecting system including the tissue resecting device.SOLUTION: A tissue resecting device includes an outer sleeve having an axial bore extending along a longitudinal axis from a proximal end to a distal end and opening to an outer window near the distal end. An inner sleeve is rotatably received in the axial bore of the outer sleeve and has an axial channel adapted for communication with a negative pressure source. A distal housing is attached to a distal end of the inner sleeve and has an annular dielectric portion and a circumferentially adjacent annular metal portion having an inner window with circumferentially spaced-apart sharp cutting edges that opens to the axial channel. An active electrode is carried by the annular dielectric portion, and the inner window is circumferentially spaced-part from the active electrode so that the inner window and the active electrode rotate alternately into alignment with the outer window as the inner sleeve is rotated within the outer sleeve.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates generally to medical devices and methods, and more particularly to a medical system including a motor-driven tubular cutter portion configured for both mechanical and electrosurgical cutting, ablation and blood coagulation procedures. (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Patent Application No. 16 / 792,099 (Attorney Docket No. 41879-750.201), filed February 14, 2020, which claims the benefit of U.S. Provisional Patent Application No. 62 / 940,455 (Attorney Docket No. 41879-750.101), filed November 26, 2019, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Surgical procedures such as subacromial decompression, anterior cruciate ligament reconstruction with notch formation, and endoscopic including arthroscopic resection of the acromioclavicular joint require the cutting and removal of bone and soft tissue. Currently, surgeons use arthroscopic shavers and cutters with rotating cutting surfaces to remove hard tissue during these procedures.

[0003] To promote efficiency, endoscopic tool systems have been proposed that include a reusable handpiece and a selection of interchangeable tool probes with different working ends, each of which may have two or more functions, such as soft tissue removal and hard tissue resection, such that such tool systems can provide dozens of specific functions, providing great flexibility. Summary of the Invention [Problem to be solved by the invention]

[0004] Of particular interest to the present invention, tool probes can be provided with both mechanical cutting and electrosurgical ablation capabilities. Mechanical cutters are often the most efficient choice for cutting and ablating hard tissues such as bone, while electrosurgical ablation is often preferred for treating soft tissues. However, the ablation electrodes on such tools can also be used to provide electrical current to cauterize bleeding tissue resulting from ablation, cutting, or other trauma during the procedure.

[0005] However, one challenge with such combined mechanical / electrosurgical ablation probes is that the delivery of ablation current from the ablation electrode can degrade the mechanical cutting blades. Such degradation is a particular problem with sharp metal cutting edges, where the inventors have discovered that the ablation current can be focused on the sharp metal cutting edges, rapidly rendering them unsuitable for ablation of hard tissue.

[0006] It is therefore an object of the present invention to provide improved surgical systems and methods of use, such as an improved arthroscopic tissue cutting and removal system, in which a motor-driven electrosurgical device is provided for cutting and removing bone or soft tissue from a joint or other site. A further object of the present invention is to provide a combination mechanical / electrosurgical cutter in which degradation of the mechanical cutting element is reduced or eliminated. In particular, it is desirable to provide a metal cutter having a cutting window with a sharp cutting edge that can be exposed to both resection and cauterizing currents without losing the ability to mechanically cut hard tissue such as bone. At least some of these objects are met by the invention described herein. [Means for solving the problem]

[0007] The present invention provides a combined mechanical ablation and electrosurgical treatment probe suitable for arthroscopy and other endoscopic and minimally invasive medical procedures. In particular, the probe of the present invention includes a rotating inner sleeve portion having a distal inner window with a sharp metal cutting edge rotatable within an outer sleeve having a distal outer window with a cooperating sharp metal cutting edge. The rotating inner sleeve portion typically has a tubular configuration and has a vacuum assisted extraction channel therethrough. An active electrosurgical electrode is carried on the rotating inner sleeve and is typically positioned at or near a distal end opposite the inner window. In a method of use, rotation of the inner sleeve portion can be stopped to position and expose the active electrosurgical electrode within the outer window of the outer sleeve. The active surgical electrode is used to selectively deliver a cauterizing current as well as a cauterizing current. It has been found by the inventors that delivery of ablation current when the active surgical electrode is in close proximity to the sharp metal cutting edge of the outer window presents a substantial risk of degrading the sharp outer window cutting edge due to the current flux concentrated at such sharp cutting edge. However, the inventors have further discovered that the sharp metal cutting edge of the outer window can be protected and preserved by positioning the return electrode surface on a rotating inner sleeve portion where the return electrode surface is positioned between the cutting electrode and the sharp cutting edge of the outer window when an active surgical electrode is positioned within the outer cutting window (typically positioned at the center of rotation). In particular, by positioning the return electrode surface on the inner sleeve portion closer to the cutting electrode than the outer window cutting edge (while maintaining a sufficient distance to allow bipolar current flow in a therapeutic environment), the return current can be preferentially directed to the return electrode surface of the inner sleeve such that less current is received by the metal cutting edge of the outer window that forms the return electrode surface. In this manner, the inventors believe that the current crowding at the sharp cutting edge of the outer window can be sufficiently reduced to reduce or eliminate degradation of such sharp cutting edge. Such sharp outer window cutting edges are at high risk of degradation, at least in part, due to the current crowding found in all sharp metal cutting edges.By directing the return current to a return electrode surface that is generally free of such current crowding features and away from the outer window cutting edge, the sharpness of the outer window cutting edge can be preserved.

[0008] In a first aspect of the invention, a tissue excision device includes an outer sleeve and an inner sleeve. The outer sleeve extends along a longitudinal axis from a proximal end to a distal end and has an axial bore opening into an outer window near the distal end. An inner sleeve portion has an axial channel rotatably received within the axial bore of the outer sleeve and adapted to communicate with a negative pressure source. A distal housing is attached to the distal end of the inner sleeve, the distal housing including an annular dielectric portion and a circumferentially adjacent annular metallic portion having an inner window with sharp cutting edges at circumferentially spaced portions opening into the axial channel. An active electrode is carried on the annular dielectric portion, the inner window being circumferentially spaced from the active electrode such that when the inner sleeve portion is rotated within the outer sleeve, the inner window and the active electrode alternately rotate into alignment with the outer window.

[0009] In certain embodiments, the outer window in the outer sleeve is circumferentially wider than the annular dielectric portion of the distal housing such that the annular dielectric portion may be terminated within the outer window leaving an edge portion of the annular metallic portion exposed between the annular dielectric portion and at least one edge of the outer window, such that the exposed annular metallic portion acts as a return electrode to prevent current crowding at at least one edge of the outer window, i.e., the return electrode defined by the annular metallic portion of the distal housing preferentially collects current from the active electrode because the return electrode is closer to and larger than the cutting edge of the outer window, thus limiting or eliminating damage to the cutting edge of the outer window that could occur if the cutting edge acted as the primary return electrode.

[0010] In further embodiments, the annular metallic portion and the annular dielectric portion will extend a full 360° about the transverse plane of the distal housing portion proximal to the inner window. In a particular example, the electrode is mounted on the annular dielectric portion (typically within a channel or recess such that the outer surface of the active electrode follows the same outer curvature as the annular dielectric portion) and has a surface that extends in an arc over at least about 20° of the transverse plane, while the annular dielectric portion has a surface that extends in an arc over at least 10° on either side of the electrode, and the annular metallic portion has a sidewall on either side of the inner window that extends in an arc over at least 10° of the transverse plane.

[0011] In a further example, the distance between each sharp cutting edge of the annular metal portion and the adjacent annular dielectric portion extends over an arc of at least 10 degrees. Such a distance ensures that the active electrode and adjacent return electrode are separated by a minimum distance to allow for optimal bipolar operation. Typically, the active electrode surface spans a circumferential distance of at least 0.030 inches, and the active electrode cutting edge is spaced at least 0.010 inches from the nearest surface of the annular metal portion (forming the return electrode).

[0012] In another exemplary embodiment, the cross section of the distal housing and the areas of the active electrode, dielectric surface and return electrode have a generally circular cross section, with the active electrode having a radius R1, the outside of the annular dielectric portion having a radius R2 and the outside of the annular metal portion having a radius R3. Typically, R1 is less than R2 by a distance of 0.020 inches or less, and R2 may be less than R3 by a distance of 0.020 inches or less. Such a small difference allows the electrode and annular dielectric portion to be slightly inserted against the cylindrical surface of the annular metal portion, reducing the risk of wear and degradation of the active electrode during rotation.

[0013] In certain embodiments of the tissue excision device of the present invention, the active electrode has an outer surface diametrically opposed to the inner window formed in the annular metal portion of the distal housing, and the dielectric portion is diametrically opposed to the inner window. During use of the device, the controller is configured to stop rotation of the inner sleeve to position and expose the electrode and dielectric portion within the outer window of the outer sleeve. By providing a selected circumferential spacing between the active electrode and the sharp cutting edge of the outer window and positioning the return electrode portion of the inner sleeve within that space, degradation of the sharp cutting edge of the outer window is minimized. In particular, positioning the surface area of ​​the return electrode formed by the annular metal portion between the active electrode and the sharp cutting edge of the outer window reduces current crowding experienced by the outer window cutting edge. The present invention is not limited to the active electrode and dielectric portion being diametrically opposed to the inner window, and the electrode and dielectric portion may be asymmetrically positioned relative to the inner window in other embodiments, so long as sufficient available return electrode area of ​​the inner sleeve is maintained between the active electrode and the sharp cutting edge of the outer window when the inner sleeve is in the parked position.

[0014] In other specific embodiments of the tissue resection device of the present invention, the sharp cutting edge on the inner window may be in the form of a straight cutting edge, a serrated cutting edge, a cutting edge having cutting teeth formed therein, and any other form of resection edge known to be effective on all types of tissue, particularly hard tissue such as bone.

[0015] In yet another particular aspect of the tissue ablation device of the present invention, the distal housing can include a conductive tubular structure having an axial channel formed in its wall, and a dielectric insert can be disposed within the axial channel to form an annular dielectric portion, where an annular metallic portion of the distal housing is provided by an adjacent wall of the conductive tubular structure.

[0016] In yet another aspect of the invention, a method of ablating tissue includes providing a probe having an elongate shaft with coaxial outer and inner sleeves having outer and inner ablation windows at their respective distal ends. The inner sleeve portion is rotatable within the outer sleeve, the inner sleeve portion carrying an active electrode and a return electrode. The inner and outer ablation windows are engaged against tissue while rotating or rotationally oscillating the inner sleeve portion, thereby ablating the tissue, and RF current is supplied to the active electrode to apply energy to the tissue. An ablation RF current can be supplied with the inner sleeve in its parked position to ablate tissue in a first mode. A coagulation RF current can be supplied with the inner sleeve in its parked position to coagulate bleeding tissue in a second mode. Also, a coagulation RF current can be supplied while rotating the inner sleeve to simultaneously ablate and coagulate tissue in a third mode.

[0017] In such a case, an elongated electrical conductor may be disposed within the axial bore of the inner sleeve, may be connected to the active electrode at a distal end, and may have a proximal end that may be connected to an electrosurgical power source (typically a hub as described in more detail below).

[0018] In a further example, a proximal hub may be attached to the tissue resection device, typically fixedly attached to the proximal end of the outer sleeve and rotatably attached to the proximal end of the inner sleeve, and the proximal hub is typically removably connectable to a handle or other handheld unit having a motor configured to rotate the inner sleeve portion relative to the outer sleeve and the proximal hub.

[0019] The present invention also provides a tissue ablation system that includes any of the tissue ablation devices described above in combination with a handle or other handheld unit, particularly a tissue ablation device having a proximal hub configured to rotate the inner sleeve portion relative to the outer sleeve and provide electrical connections to the active and return electrodes. Such tissue ablation systems may further include a handpiece configured to removably connect to the proximal hub. The handpiece typically includes a motor drive unit configured to rotate the inner sleeve portion and the inner window relative to an outer window in the outer sleeve through open and closed window positions. A controller may be provided on the handle or other handheld unit, the controller adapted to selectively drive the motor to rotate the inner sleeve, stop the motor drive rotation of the inner sleeve, supply an ablation current to the active electrode, and supply a cauterization current to the active electrode, either individually or in various combinations.

[0020] Using such a tissue resection system, the method of the present invention includes engaging an outer window of the outer sleeve with a target tissue site and manipulating the controller to rotate the inner sleeve portion and the inner window relative to the outer window to mechanically resect the tissue with a sharp cutting edge. Although any tissue may be resected, the sharp cutting edge is particularly effective for resecting soft tissue and bone.

[0021] The method further includes operating the controller to stop rotation of the inner sleeve portion having the active electrode aligned with the outer window of the outer sleeve and to supply an ablation current to the active electrode to ablate tissue. Although any type of tissue may be ablated, radio frequency and related forms of electrosurgical ablation are particularly effective on soft tissue.

[0022] By having mechanical tissue ablation available to treat hard tissue, such as bone, as well as electrosurgical tissue ablation available to treat soft tissue, the same device can be conveniently used to treat both bone and soft tissue in procedures where it is difficult or undesirable to exchange instruments, such as arthroscopic procedures, where it may be difficult to reposition a second probe or tool after the initial procedure is completed with a first probe or tool.

[0023] In yet another aspect, the tissue ablation probe of the present invention has seals proximal and distal to the electrical contacts within the hub. For example, the proximal hub may be coupled to an elongated outer sleeve extending about a longitudinal axis, with the hub housing having a distal end with an opening therein. The rotatable inner sleeve portion may be configured to rotate within the hub and outer sleeve, with the inner sleeve portion extending to a working end that passes through the opening. The inner sleeve portion may carry an electrical contact ring configured to rotatably contact a non-rotating electrical contact within the hub, and first and second annular seals may be carried by the hub contacting and sealing the inner sleeve portion proximal and distal to the contact ring to provide a fluid-tight seal around the contact ring and the non-rotating contact.

[0024] In a particular example, the contact ring may be coupled to an active electrode carried at the working end of the inner sleeve by an electrical lead, which may be carried in a passageway inside the wall of the inner sleeve. The electrical lead may be positioned on the outer wall or within an axial bore in the inner sleeve portion to complete the current path. The hub may be configured to releasably mate with a receiving channel in a handpiece carrying the motor drive unit, and the receiving channel may carry an active contact configured to electrically couple with a non-rotating contact of the hub when the probe is attached to the handpiece. The receiving channel may also carry a return contact that engages an electrical contact in the hub that provides RF current to a return electrode carried by the outer sleeve.

[0025] In yet another embodiment, the distal housing of the present invention has a continuous (usually circular) wall having a thickness in the radial direction, where a first portion of the wall, typically an annular segment, has a complete wall thickness that is completely metallic, and a second portion of the wall, typically an annular segment, has a complete wall thickness that is completely ceramic in the radial direction, i.e., the wall structure is not layered which increases the wall thickness and reduces the cross-sectional area available for the axial bore required to accommodate tissue debris extraction.

[0026] For example, a tissue ablation probe may comprise an elongate outer sleeve extending about a longitudinal axis, with a distal portion having an outer window opening into an axial bore therein. An inner sleeve portion may be configured to rotate within the bore, with the inner sleeve portion including a distal housing assembly having an inner window opening into an inner channel. The housing assembly may include a metal wall portion and a ceramic or other dielectric wall portion defining said inner channel, with the total wall thickness along any radial vector being metal or dielectric, typically ceramic. Typically, the inner surface of the dielectric wall portion will comprise the surface of the inner channel. An outer surface of the dielectric wall portion may carry an electrode, and the metal wall portion may define a cross cutting edge of the inner window.

[0027] Various embodiments of the present invention will now be described with reference to the accompanying drawings, in which it will be understood that the drawings depict only typical embodiments of the invention and therefore should not be considered limiting of the scope. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a perspective view of an arthroscopic cutting system including a reusable handpiece with a motor drive unit and a detachable, single-use cutting probe, the cutting probe is shown in two orientations such that it may be coupled to the handpiece and may be oriented in an up or down orientation relative to the handpiece, and the handpiece includes an LCD screen for displaying operating parameters of the system on the handpiece during use along with a control actuator. [Figure 2A]FIG. 2A is an enlarged longitudinal cross-sectional view of the hub of the probe of FIG. 1 taken along line 2A-2A of FIG. 1 with the hub and probe oriented upward relative to the handpiece, and further shows a Hall effect sensor carried by the handpiece and multiple magnets carried by the probe hub for device identification to determine the orientation of the probe and the position of the motor drive element of the probe relative to the handpiece. [Figure 2B] FIG. 2B is a cross-sectional view of the hub of FIG. 1 taken along line 2B-2B of FIG. 1, with the hub and probe oriented downward relative to the handpiece showing the Hall effect sensor and magnet having a different orientation compared to that of FIG. 2A. [Figure 3A] 3A is an enlarged perspective view of the working end of the probe of FIG. 1 positioned upward with the rotatable cutter portion in a first position relative to the outer sleeve, with the window in the cutter portion aligned with the window in the outer sleeve. [Figure 3B] 3B is a perspective view of the working end of FIG. 1 positioned upward with the rotatable cutter portion in a second position relative to the outer sleeve, in which the electrode carried by the cutter portion is aligned with the centerline of the window in the outer sleeve. [Figure 4] 4 is a perspective view of a working end of a variation of a probe that may be removably coupled to the handpiece of FIG. 1, the working end including a bone cutter portion extending distally from an outer sleeve. [Diagram 5] FIG. 5 is a perspective view of a working end of a variation of a probe that can be removably coupled to the handpiece of FIG. 1, the working end having a reciprocating electrode. [Figure 6] FIG. 6 is a perspective view of a working end of another variation of a probe that can be removably coupled to the handpiece of FIG. 1, the working end having a hook-shaped electrode having an extended position and a non-extended position. [Figure 7] FIG. 7 is a perspective view of a working end of yet another variation of a probe that may be removably coupled to the handpiece of FIG. 1, the working end having an openable and closable jaw structure for cutting tissue. [Figure 8]FIG. 8 is a chart of set speeds for a probe having a rotating cutter portion such as those of FIGS. 1 and 3A, illustrating generally the method used by the control algorithm to stop rotation of the cutter portion at a selected default position. [Figure 9A] Figure 9A is a longitudinal cross-sectional view of a probe hub similar to that of Figure 2A, except that the hub of Figure 9A has an internal cam mechanism to convert rotary motion to linear motion to axially reciprocate the electrode as in the working end of Figure 5, and the magnets and drive coupling within the hub are the same as those of Figure 2A, and the hub is in an upright position relative to the handpiece. [Figure 9B] FIG. 9B is a cross-sectional view of the hub of FIG. 9A rotated 180 degrees in a downward position relative to the handpiece. [Figure 10] FIG. 10 is a perspective view of another variation of the probe showing a motor-driven rotating inner cutting sleeve including a longitudinal dielectric structural portion coupled to a longitudinal conductive metal portion, the dielectric structural portion carrying the active electrode and the longitudinal conductive metal portion including the return electrode. [Figure 11] FIG. 11 is an enlarged perspective view of the working end of FIG. 10 with the inner sleeve portion separated from the outer sleeve. [Figure 12] FIG. 12 is a perspective view of the working end as in FIG. 11, with the inner sleeve portion rotated 180°. [Figure 13] 13 is a perspective exploded view showing components of the working end of the probe of FIG. 10. FIG. [Figure 14] FIG. 14 is an exploded perspective view of a working end as in FIG. 13 rotated 180° to show another side of its components. [Figure 15] FIG. 15 is a perspective view of the working end of FIGS. 10-14, partially assembled, showing electrical connections therein. [Figure 16A] FIG. 16A is an end view of the components of the working end of FIGS. 10-15 showing the radial dimensions of the components and their features. [Figure 16B]16B is an end view of the components of the working end of FIG. 1 in an exploded view. [Figure 16C] 16C is a cross-sectional view of the working end components of FIGS. 13-14 taken along line 16C-16C of FIG. 14 and rotated 90 degrees with the components moved apart. [Figure 17] FIG. 17 is a perspective view of the working end of FIGS. 10-15, showing the RF current path between the active and return electrodes. [Figure 18] FIG. 18 is an exploded perspective view of the working end of another variation of a probe similar to that of FIG. 10, showing its components. [Figure 19] FIG. 19 is an end view of the components of the working end of FIG. [Figure 20] FIG. 20 is an exploded perspective view of another variation of a probe similar to those of FIGS. 10 and 18, showing its components. [Figure 21] FIG. 21 is an end view of the components of the working end of FIG. [Figure 22] FIG. 22 is a partially exploded perspective view of another variation of a probe similar to those of FIGS. 10 and 18, showing its components. [Diagram 23] 23 is another perspective view of the components of the working end of FIG. 22. FIG. [Figure 24] FIG. 24 is an exploded view of the components of the probe of FIGS. 22 and 23. [Figure 25A] FIG. 25A is a perspective view of the probe of FIGS. 22 and 23, showing the hub and shaft of the probe. [Figure 25B] FIG. 25B is a longitudinal cross-sectional view of the probe of FIG. 25A. [Figure 26] FIG. 26 is an enlarged cross-sectional view of a portion of the hub of the probe of FIG. 25B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The present invention relates to a bone cutting and tissue removal device and related method of use. Several variations of the invention are now described to provide a general understanding of the principles of form, function, and method of use of the device disclosed herein. In general, the present disclosure provides variations of arthroscopic tools adapted for cutting bone, soft tissue, meniscal tissue, and for RF ablation and coagulation. The arthroscopic tools are typically disposable and configured to removably couple to a non-disposable handpiece carrying a motor drive element. This description of the general principles of the invention is not meant to limit the inventive concept in the appended claims.

[0030] 1, an arthroscopic system 100 of the present invention provides a handpiece 104 with a motor drive unit 105 and a disposable shaver assembly or probe 110 having a proximal hub 120 that can be received by a receiver or passageway 122 of the handpiece 104. In one aspect, the probe 110 has a working end 112 that carries a high speed rotary cutter configured for use in many arthroscopic surgical applications, including, but not limited to, treating bones of the shoulder, knee, hip, wrist, ankle, and spine.

[0031] 1, 2A and 3A, it can be seen that the probe 110 comprises an outer sleeve 140 and an inner sleeve portion 142 having a shaft 125 extending along a longitudinal axis 128 carrying a distal ceramic cutter portion 145 (FIG. 3A). The shaft 125 extends from a proximal hub 120, where the outer sleeve 140 is coupled in a fixed manner to the hub 120, which can be, for example, an injection molded plastic, into which the outer sleeve 140 is insert molded. The inner sleeve portion 142 is coupled to a drive coupling 150 configured to couple to a rotating motor drive shaft 151 of the motor drive unit 105. More specifically, the rotatable cutter portion 145 is made of a ceramic material having sharp cutting edges on opposing sides 152a and 152b of a window 154 for cutting soft tissue. A motor drive unit 105 is operably coupled to the ceramic cutter and rotates the cutter portion at speeds ranging from 1,000 rpm to 20,000 rpm. In FIG. 3B, the cutter portion 145 can be seen to also carry an RF electrode 155 on a surface facing the window 154. The cutter portion 145 rotates to shear tissue within a toothed opening or window 158 in the outer sleeve 140 (FIG. 3A). Probes of the type shown in FIG. 1 are described in more detail in co-pending and commonly owned U.S. patent application Ser. No. 15 / 421,264, entitled ARTHROSCOPIC DEVICES AND METHODS, filed Jan. 31, 2017 (Attorney Docket No. 41879-714.201), which is incorporated herein by reference in its entirety.

[0032] 1, the probe 110 is shown in two orientations for releasably coupling to the hand piece 104. More specifically, the hub 120 can be coupled to the hand piece 104 in an upward orientation, indicated as UP, and a downward orientation, indicated as DN, where the orientations are 180° opposite one another. It can be appreciated that the upward and downward orientations are necessary to orient the working end 112 either upward or downward relative to the hand piece 104, allowing the physician to interface the cutter portion 145 with the target tissue in all directions without having to manipulate the hand piece 360° to access the tissue.

[0033] In FIG. 1, the handpiece 104 is seen to be operatively coupled by an electrical cable 160 to a controller 165 that controls the motor drive unit 105. Actuator buttons 166a, 166b or 166c on the handpiece 104 can be used to select operating modes, such as various rotation modes for the ceramic cutter portion 145. In one variation, a joystick 168 can be moved back and forth to adjust the rotation speed of the ceramic cutter portion 145. The rotation speed of the cutter can be continuously adjustable or can be incrementally adjusted up to 20,000 rpm. An LCD screen 170 is provided within the handpiece for displaying operating parameters, such as the rotation speed of the cutter portion, the operating mode, etc.

[0034] It can be seen from Figure 1 that the system 100 and handpiece 104 are adapted to use a variety of disposable probes that may be designed for a variety of different functions and procedures. For example, Figure 4 shows a different variation of a probe working end 200A that is similar to the working end 112 of the probe 110 of Figures 3A-3B, except that a ceramic cutter portion 205 extends distally from an outer sleeve 206 and the cutter portion has a cutter edge 208 for cutting bone. The probe of Figure 4 is described in more detail in co-pending and commonly owned U.S. patent application Ser. No. 15 / 271,184, filed Sep. 20, 2016, entitled ARTHROSCOPIC DEVICES AND METHODS (Attorney Docket No. 41879-728.201). 5 shows a different variation of the working end of a probe 200B having a reciprocating electrode 210 of the type of probe described in more detail in co-pending and co-owned U.S. patent application Ser. No. 15 / 410,723, filed Jan. 19, 2017, entitled ARTHROSCOPIC DEVICES AND METHODS (Attorney Docket No. 41879-713.201). In another example, Fig. 6 shows another variation of the working end of a probe 200C having a retractable hook-shaped electrode 212 of the type of probe described in more detail in co-pending and co-owned U.S. patent application Ser. No. 15 / 454,342, filed Mar. 9, 2017, entitled ARTHROSCOPIC DEVICES AND METHODS (Attorney Docket No. 41879-715.201). In yet another example, FIG. 7 illustrates a variation of the working end of a probe type 200D having an openable and closable jaw structure 215 actuated by a reciprocating portion 218 for trimming meniscal or other tissue, as described in more detail in co-pending and commonly owned U.S. patent application Ser. No. 15 / 483,940, filed Apr. 10, 2017, entitled ARTHROSCOPIC DEVICES AND METHODS (Attorney Docket No. 41879-721.201).All of the probes of Figures 4-7 may have hubs similar to hub 120 of probe 110 of Figure 1 for coupling to the same handpiece 104 of Figure 1, and some of the probes (see Figures 5-7) have hub mechanisms for converting rotational to linear motion. All of the patent applications just identified in this paragraph are incorporated herein by reference.

[0035] FIG 1 further illustrates that the system 100 also includes a negative pressure source 220 coupled to an aspiration tube 222 that communicates with a flow path 224 in the hand piece 104 and can cooperate with any of the probes 110, 200A, 200B, or 200C of FIGS. 1-3B, 4, 5, and 6. FIG 1 also illustrates that the system 100 includes an RF source 225 that can be connected to an electrode of any of the probes 110, 200A, 200B, or 200C of FIGS. 1-3B, 4, 5, and 6. A controller 165 and a microprocessor having control algorithms therein is provided for operating and controlling all functions, including controlling the motor drive unit 105 to move the motor drive elements at the working end of any of the probes 110, 200A, 200B, or 200C, as well as controlling the RF source 225 and the negative pressure source 220 that can aspirate fluid and tissue debris into a collection reservoir 230.

[0036] As can be seen from the above description of the system 100 and hand piece 104, the controller 165 and control algorithms need to be configured to perform and automate many tasks to provide the system functionality. In a first embodiment, a control algorithm is required for device identification, so that when any of the different types of probes 110, 200A, 200B, 200C or 200D of Figures 1 and 4-7 are coupled to the hand piece 104, the controller 165 recognizes the probe type and then selects algorithms for operating the motor drive unit 105, RF source 225 and negative pressure source 220 as required for the particular probe. In a second embodiment, the controller is configured with algorithms to identify whether the hand piece 104 is coupled in an up or down orientation relative to the hand piece, with each orientation requiring a different subset of operating algorithms. In another embodiment, the controller has separate control algorithms for each type of probe, where some probes have rotatable cutters and other probes have reciprocating electrodes or jaw structures. In another aspect, in most cases, not all of the probes 110, 200A, 200B, 200C and 200D (FIGS. 1, 4-7) require a default "stop" position where the motor drive element stops at a particular orientation within the working end. For example, a rotatable cutter 145 with electrode 155 should have the electrode centered within the outer sleeve window 158 in the default position as depicted in FIG. 3B. Some of these systems, algorithms and methods of use are described below.

[0037] 1 and 2A-2B, it can be seen that the handpiece 104 carries a first Hall effect sensor 240 in a distal region of the handpiece 104 adjacent the receiving passageway 122 that receives the hub 120 of the probe 110. FIG. 2A corresponds to the probe 110 with the working end 112 of FIG. 1 in an upward orientation, UP. FIG. 2B corresponds to the probe 110 of FIG. 1 with the working end 112 of FIG. 1 in a downward orientation, DN. The handpiece 104 carries a second Hall effect sensor 245 adjacent the rotatable drive coupling 150 of the probe 110. The probe 110 carries a number of magnets which interact with Hall effect sensors 240, 245 as described below to provide a number of control functions in cooperation with a control algorithm, including (i) identification of the type of probe coupled to the handpiece, (ii) an upward or downward orientation of the probe hub 120 relative to the handpiece 104, and (iii) the rotational position and speed of the rotary drive coupling 150 which can determine the position of either the rotating or reciprocating motor drive element.

[0038] The cross-sectional views of Figures 2A-2B show that the hub 120 of the probe 110 carries first and second magnets 250a, 250b on its surface portion. A Hall sensor 240 in the hand piece 104 is axially aligned with one of the magnets 250a, 250b when the probe hub 120 is coupled to the hand piece 104 either upwards (Figures 1 and 2A) or downwards (Figures 1 and 2B). In one embodiment as outlined above, the combination of the magnets 250a, 250b and the Hall sensor 240 can be used to identify the type of probe. For example, a product portfolio can have 2-10 or more types of probes as shown in Figures 1 and 4-7, and each such probe type can carry magnets 250a, 250b with a specific different magnetic field strength. The Hall sensor 240 and control algorithm can then be adapted to read the magnetic field strength of the specific magnet in the probe, which can be compared to a library of field strengths corresponding to the specific probe type. A Hall identification signal can then be generated or otherwise provided to the controller 165 to select a control algorithm for operating the identified probe, which control algorithm can include parameters for operating the motor drive unit 105, the vacuum source 220 and / or the RF source 225 as may be required for the probe type. As can be seen in Figures 1, 2A and 2B, the probe hub 120 can be coupled to the handpiece 104 in an up and down orientation in which the north (N) and south (S) poles of the magnets 250a, 250b are reversed relative to the longitudinal axis 128 of the probe. Thus, the Hall sensor 240 and associated algorithm look for magnetic field strength regardless of polarity to identify the probe type.

[0039] 1, 2A-2B and 3A-3B, first and second magnets 250a, 250b having different orientations of north (N) and south (S) poles relative to the central longitudinal axis 128 of the hub 120 are also used to identify an upward orientation UP or a downward orientation DN of the hub 120 and the working end 112. In use, as described above, a physician may couple the probe 110 to the handpiece receiving passageway bore 122 with the working end 112 facing up or down based on his or her preference and the target tissue. It can be appreciated that because the orientation or rotation of the cutter portion 145 relative to the handpiece and Hall sensor 240 changes by 180°, the control algorithm configured to stop the rotation of the cutter portion 145 in the window 158 of the outer sleeve 104 of the working end 112 must "learn" whether the working end is facing up or down. The Hall effect sensor 240, together with a control algorithm, can determine an upward orientation UP or a downward orientation DN by sensing whether the north (N) or south (S) pole of either the magnets 250a, 250b is facing upward and is in close proximity to the Hall effect sensor 240.

[0040] In another aspect of the invention, in probe 110 (FIG. 1) and other probes, a motor driven portion of the working end, such as the rotating cutter portion 145 of working end 112 of FIGS. 1 and 3A-3B, must be stopped at a selected rotational position relative to a cutting opening or window 158 in outer sleeve 140. Other probe types may have reciprocating portions or jaw structures as described above, which also require a control algorithm to stop the movement of the moving element at a selected position, such as the axially moving electrode of FIGS. 5-6 and the jaw structure of FIG. 7. In all probes, the motor drive unit 105 is coupled to a rotary drive coupling 150, so sensing the rotational position of the drive coupling 150 can be used to determine the orientation of the motor driven element at the working end. 1 and 2A-2B, the drive coupling 150 carries a third and fourth magnet 255a or 255b, whose north (N) and south (S) poles are reversed relative to the longitudinal axis 128 of the probe. Thus, the Hall effect sensor 245 senses when each magnet passes it, and can thereby determine the exact rotational position of the drive coupling 150 twice on each of its revolutions (once for each magnet 255a, 255b). A control tachometer algorithm using a clock can then determine and optionally display the rotational speed RPM of the drive coupling 150 and, for example, the cutter portion 145 of FIG. 3A.

[0041] In another aspect of the invention, the Hall effect sensor 245 and magnets 255a, 255b (FIGS. 1 and 2A) are used in a set of control algorithms to stop the rotation of the motor drive element at a preselected rotational position of the working end, e.g., cutter portion 145 of FIGS. 1 and 3A-3B. In FIG. 3A, it can be seen that the inner sleeve portion 142 and the cutter portion 145 and window 154 "first side" therein are resting and positioned centrally in the window 158 of the outer sleeve 140. The rest position of the cutter portion 145 and window 154 of FIG. 3A may be used for irrigation or flushing of the working space to allow maximum fluid outflow through the probe.

[0042] FIG. 3B shows the inner sleeve portion 142 and the "second side" of the cutter portion 145 disposed about the centerline of the window 158 in the outer sleeve 140. The rest or stop position of the cutter portion 145 in FIG. 3B is required to use the RF electrode 155 to ablate or coagulate tissue. Because the outer sleeve 140 typically includes a return electrode 260, it is important that the RF electrode 155 remains along the centerline of the window 158 in the outer sleeve. The position of the RF electrode 155 in FIG. 3B is referred to herein as the "centerline default position." If the cutter portion 145 and electrode 155 are rotated so that they are close to the edge 262a or 262b of the window 158 in the outer sleeve 140, the RF current may arc between the electrodes 155 and 260, potentially causing a short circuit that disables the probe. Therefore, a robust and reliable stop mechanism is required, as described below.

[0043] As can be seen from Figures 1 and 2A-2B, the controller 165 can constantly determine the rotational position of the drive coupling 150 in real time, and therefore the angular or rotational position of the ceramic cutter portion 145 and the RF electrode 155. The control algorithm can further calculate the angle of rotation of the RF electrode 155 away from the centerline default position because the Hall effect sensor 245 can sense the decrease in magnetic field strength when the magnet 255a or 255b in the drive coupling 150 rotates the RF electrode 155 away from the centerline default position. Each magnet has a designated known strength, and the algorithm can use a lookup table that lists the magnetic field strength that corresponds to the degree of rotation away from the default position. Thus, when the Hall signal responsive to the rotational position of the magnet 255a or 255b drops a certain amount from a known peak value at the centerline initial position, that is the means for the electrode 155 to move away from the center of the window 158. In one variation, if the electrode 155 moves a selected rotational angle away from the centerline position during RF energy delivery to the electrode, the algorithm instantly turns off the RF current and alerts the physician with an audible and / or visual signal, such as a warning on the LCD screen 170 on the handpiece 104 and / or on a screen on the controller console (not shown). Thus, the termination of the RF current delivery prevents electrical arcing potential between the electrode 155 and the outer sleeve electrode 260.

[0044] It can be appreciated that in use, when the RF electrode 155 is in the position shown in FIG. 3B, the physician may move the energized electrode over tissue to ablate or coagulate the tissue. During such use, the cutter portion 145 and electrode 155 may engage or catch tissue that inadvertently rotates the electrode 155 from its default centerline position. Accordingly, the system provides a control algorithm, referred to herein as an “active electrode monitoring” algorithm, in which the controller continuously monitors the position signal generated by the Hall effect sensor 245 during RF energy delivery in both ablation and coagulation modes to determine whether the electrode 155 and inner sleeve portion 142 have bumped out of the centerline position. In a variation, if the electrode 155 has been bumped out of the centerline position, the control algorithm can then be configured to restart the motor drive unit 105 to return the inner sleeve portion 142 and electrode 155 to their default centerline position sleeve. In another variation, the control algorithm can be configured to automatically again supply RF current to the RF electrode 155 when the RF electrode 155 is returned to its default centerline position. Alternatively, the controller 165 can request that the physician manually restart the delivery of RF current to the RF electrode 155 when it has been moved back to the centerline position. In one aspect of the invention, the drive coupling 150, and thus the magnets 255a, 255b, are mounted on the inner sleeve portion 142 and the cutter portion 145 at a predetermined angular relationship to the longitudinal axis 128 such that the Hall sensors generate signals responsive to the magnets 255a, 255b that are the same for all probes within a probe type, thus allowing the control algorithms to function properly.

[0045] Turning now to the stopping mechanism or algorithm for stopping the movement of the motor drive element of the working end 112, FIG. 8 shows the algorithm and steps of the stopping mechanism in a schematic manner. In one variation, referring to FIG. 8, a stopping mechanism according to the present invention (i) uses a dynamic braking method and algorithm to stop the rotation of the inner sleeve portion 142 and the cutter portion 145 (FIGS. 1, 3A-3B) at an initial position, and then (ii) uses a secondary check algorithm to check the initial stopping position achieved by the dynamic braking algorithm, and if necessary, the stopping algorithm can restart the motor drive unit 105 to slightly reverse (or advance) the rotation of the drive coupling 150 and the inner sleeve portion 142, if necessary, to position the cutter portion 145 and the electrode 155 within the centerline position or within 0°-5° of the target centerline default position. Dynamic braking is further described below. FIG. 8 shows in a schematic manner various aspects of a control algorithm for controlling the rotational speed of the cutter portion and stopping the cutter portion 145 at the default centerline position.

[0046] In FIG. 8, it can be seen that the controller 165 operates the probe 110 of FIGS. 1 and 3A-3B at a "set speed" which may be a PID controlled continuous rotation mode or an oscillating mode in which the motor drive unit 105 rotates the cutter portion 145 in one direction and then reverses the rotation as known in the art. At higher rotation speeds, such as 1,000 RPM to 20,000 RPM, it is not practical or feasible to obtain a signal from the Hall sensor 245 indicative of the position of the magnets 255a or 255b in the drive coupling 150 to apply a stopping algorithm. In FIG. 8, when the physician stops cutting with the probe 110 by deactivating the actuator button or foot pedal, the current to the motor drive unit 105 is turned off. The control algorithm then monitors the deceleration of the rotation of the drive coupling 150 and inner sleeve portion 142 using the Hall sensor 245 until a slower rotation speed is reached. The deceleration period may be 10 ms to 1 second, typically about 100 ms. Once a suitable slower rotational speed, referred to herein as the "search speed" (see FIG. 8), is reached, the controller 165 restarts the motor drive unit 105 to rotate the drive coupling at a slower speed, ranging from 10 RPM to 1,000 RPM, with one variation being between 50 RPM and 250 RPM. An initial "search delay" period, ranging from 50 ms to 500 ms, is provided to allow the PID controller to stabilize the rotational speed at the selected search speed. The control algorithm then monitors the Hall position signal for magnet strength, and when the magnet parameters reach a predefined threshold, e.g., when the rotational position of the drive coupling 150 and electrode 155 corresponds to the centerline default position of FIG. 3B, the control algorithm then applies dynamic braking to instantly stop the rotation of the motor drive shaft 151, drive coupling 150, and the motor drive elements of the probe. FIG. 8 further illustrates that the controller can check the magnet / drive coupling 150 position after the braking and stopping steps.If the Hall position signal indicates that the motor drive element has deviated from the target default position, the motor drive unit 105 can be restarted to move the motor drive element, after which the brakes can be reapplied as described above.

[0047] Dynamic braking, as shown diagrammatically in FIG. 8, typically occurs approximately 0.5 mm from the targeted stopping position. o ~15 o The dynamic brake can stop rotation of the drive coupling 150 with a variation up to, which can further vary depending on when different types of tissue are cut inhibiting rotation of the cutter portion 145 and whether the physician moves the cutter portion completely away from the tissue interface when the motor drive is released. Thus, dynamic braking alone cannot guarantee that the default or stop position will be within a desired variation.

[0048] As background, the dynamic braking concept is described in the literature at https: / / www.ab.com / support / abdrives / documentation / techpapers / RegenOverview01.pdf and http: / / literature.rockwellautomation.com / idc / groups / literature / documents / wp / drives-wp004_-en-p.pdf. Essentially, a dynamic braking system provides a chopper transistor on the DC bus of an AC PWM drive that feeds a power resistor that converts the regenerative electrical energy into thermal energy. The thermal energy is dissipated into the local environment. This process is commonly referred to as dynamic braking with a chopper transistor, with associated controls and elements called the chopper module, and a power resistor called the dynamic brake resistor. The entire assembly of the chopper module with the dynamic brake resistor is sometimes referred to as the dynamic brake module. The dynamic brake resistor allows any magnetic energy stored in the parasitic inductance of its circuit to be safely dissipated during the turn-off of the chopper transistor.

[0049] This method is called dynamic braking because the amount of braking torque you can apply changes dynamically as the load decelerates; that is, the braking energy is a function of the kinetic energy in the rotating mass, and as that decreases, so does the braking ability. So the faster you spin or the more inertia you have, the harder it is to brake, but as you brake slower, you hit the law of diminishing returns and at some point there is no more braking power left.

[0050] In another aspect of the invention, a method has been developed to increase the accuracy of the stopping mechanism that is a component of the positioning algorithm described above. It has been found that each magnet in a single-use probe can vary slightly from its specified strength. As described above, the positioning algorithm uses the Hall effect sensors 245 to continuously monitor the magnetic field strength of the magnets 255a, 255b as the drive coupling 150 rotates, and the algorithm determines the rotational position of the magnets and drive coupling based on the magnetic field strength as it rises and falls as the magnet rotates past the Hall sensors. It is therefore important that the algorithm has a library of magnetic field strengths that accurately correspond to the degree of rotation away from the peak Hall signal when the magnet is adjacent the sensor 245. For this reason, an initial step in the positioning algorithm includes a "learning" step that allows the controller to learn the actual field strength of the magnets 255a and 255b, which can vary from the specified strength. After a new disposable probe 110 (FIG. 1) is coupled to the handpiece 104, and following actuation of the motor drive unit 105, the positioning algorithm rotates the drive coupling at least 180°, and more frequently at least 360°, while the Hall sensors 245 quantify the magnetic field strength of the magnets 255a and 255b of that particular probe. The positioning algorithm then stores the maximum and minimum Hall signals (corresponding to the north and south poles) and calibrates a library of field strengths corresponding to various degrees of rotation away from the Hall minimum-maximum signal position when the magnets are adjacent the Hall sensors.

[0051] In general, a method of use with respect to a learning algorithm includes providing a handpiece with a proximal hub configured for removably coupling thereto, the motor drive unit configured for coupling to a rotary drive coupling in the hub, the drive coupling carrying first and second magnets having north and south poles that are differently positioned relative to the axis, coupling the hub to the handpiece, actuating the motor drive unit to rotate the drive coupling and magnets at least 180 degrees, using handpiece sensors to sense the strength of each magnet, and using the sensed strength of the magnets for calibration in a positioning algorithm responsive to varying strengths of magnets in the rotary drive coupling, thereby improving accuracy in calculating the rotational position of the drive coupling 150.

[0052] Another aspect of the invention relates to an enhanced method of use using a probe working end having an electrode such as working end 112 of Figures 1 and 3B. As described above, a positioning algorithm is used to stop the rotation of electrode 155 at the default centerline position of Figure 3B. An additional "slight oscillation" algorithm is used to contemporaneously activate motor drive unit 105 with RF current to electrode 155, specifically an RF cutting waveform for tissue ablation. The slight oscillation thus provides a form of oscillatory RF ablation. The slight oscillation algorithm rotates electrode 155 in one direction to a predetermined degree of rotation, which the control algorithm determines from the Hall position signal. The algorithm then reverses the direction of the motor drive to rotate in the opposite direction until the Hall position signal indicates that the predetermined degree of rotation has been achieved in the opposite direction away from the electrode's default centerline position. The predetermined angular movement may be any suitable rotation appropriate to the dimensions of the outer sleeve window, and in one variation is between 1° and 30° in each direction away from the centerline initial position. More often, the predetermined degree of angular movement is between 5° and 15° in each direction away from the centerline default. The slight oscillation algorithm can use any suitable PID controlled motor shaft speed, and in one variation, the motor shaft speed is from 50 RPM to 5,000 RPM, and more often from 100 RPM to 1,000 RPM. Alternatively stated, the frequency of oscillation can be from 20 Hz to 2,000 Hz, and typically from 40 Hz to 400 Hz.

[0053] While the above description of the slight vibration algorithm is provided with reference to the electrode 155 on the rotating cutter portion 145 of Figure 3B, it should be understood that the reciprocating electrode 212, such as that shown at the distal working end 200C of Figure 6, may also be operated with slight vibration. In other words, the hook-shaped electrode 212 of Figure 6 may be provided with vibration frequencies in the range of 20 Hz to 2,000 Hz, and typically in the range of 40 Hz to 400 Hz.

[0054] 9A-9B are longitudinal cross-sectional views of a probe hub 120' corresponding to the working end 200B of FIG. 5 with a reciprocating electrode 210. In FIG. 9A-9B, it is of course understood that the hand piece 104 and holes affect the sensors 240, 245 in the same manner as if there were no change in the hand piece 104 for the different types of probes. The probe hub 120' of FIG. 9A-9B is very similar to the hub 120 of FIG. 2A-2B in that the first and second identification / orientation magnets 250a, 250b are the same. The third and fourth rotational position magnets 255a, 255b are also the same and are carried by the drive coupling 150'. The probe hub 120' of FIG. 9A-9B differs only in that the drive coupling 150 rotates with a cam mechanism operatively coupled to the inner sleeve portion 142' to convert rotational motion to linear motion to reciprocate the electrode 210 in the working end 200B of FIG. 5. Similar hubs for converting rotary motion to linear motion are provided for working ends 200C and 200D of Figures 6 and 7, respectively, which each have a reciprocating portion (212, 218) thereon.

[0055] 10, 11 and 12, there is shown another variation of an arthroscopic shaver or resection probe 400 somewhat similar to that of FIGS. 1, 2 and 3A-3B, which comprises a tubular cutter portion having a proximal hub 402 coupled to an elongated shaft 405 extending about a central longitudinal axis 406. The shaft assembly comprises an outer sleeve 410 and a coaxial or concentric inner sleeve portion 415 extending to a distal or working end 418. The hub 402 is again adapted to couple to a handpiece and motor drive unit controlled by a controller 420A, which further controls the RF source 420B and the negative pressure source 420C as previously described. The controller 420A includes an algorithm having the features described in the previous embodiment for rotating the inner sleeve portion 415 as well as stopping the inner sleeve portion 415 at a selected rotational position, such as a fenestration closed or fenestration open position. The distal or working end 418 again has an outer sleeve cutting window 422 in the outer sleeve assembly 410 which cooperates with an inner sleeve portion cutting window 425 (FIG. 12) in the inner sleeve portion 415 to engage and cut tissue.

[0056] The variant or probe 400 of Figures 10, 11 and 12 differs from the previous embodiment in that the inner sleeve portion 415 of the distal or working end 418 (Figures 11, 12) is constructed from a combination of a first longitudinal portion including a dielectric structural portion or structure 440 coupled to a second longitudinal portion including a conductive structural portion or structure 442, typically formed as an insert, typically a generally tubular structure having an axial channel for receiving a dielectric insert. The dielectric structural portion 440 may be a ceramic or glass material, and the longitudinal conductive structural portion 442 is typically stainless steel or other conductive metal. When assembled, the dielectric structural portion 440 and the longitudinal conductive structural portion 442 have longitudinal surfaces that contact each other along a critical interface 444 for reasons that will be described in more detail below.

[0057] As seen in FIG. 11, which shows the elements of the inner sleeve portion 415 separated, the longitudinal dielectric structural portion 440 carries an active electrode 445, which may also be referred to herein as a "first polarity" electrode. For convenience, the side of the inner sleeve portion 415 that supports the electrode 445 is referred to as the electrode side ES, and the opposite side that supports the inner window 425 is referred to as the window side WS. With reference to FIG. 12, the inner sleeve partial resection window 425 has sharp, circumferentially spaced first and second cutting edges 448a, 448b for mechanically resecting tissue such that the cutting edges 448a, 448b shear the tissue when rotated or rotationally oscillated adjacent the cutting edges 450a, 450b of the outer sleeve window 422. In one variation shown in FIG. 12, the first and second cutting edges 448a, 448b are asymmetric with teeth on one side and no such teeth on the opposite side. It should be understood that any type of symmetrical or asymmetrical cutting edge is possible, such as serrated, straight, toothed, etc.

[0058] Of particular interest, the longitudinal conductive metallic structural portion 442 comprises a first return electrode 455A (also referred to herein as a "second polarity" electrode) which cooperates with the first polarity or active electrode 445 to deliver energy to tissue. As described below, the distal portion of the outer sleeve 410 comprises a second return electrode 455B. The active electrode 445 and the return electrodes 455A, 455B are operably coupled to the RF source 420B and the controller 420A. The outer sleeve assembly 410 extends proximally of the hub 402 and has an outer tubular portion 456 made of a conductive metal having an axial bore 458 therein that extends distally to a distal end portion or distal housing 459 carrying the outer sleeve window 422. The inner sleeve portion 415 extends proximally of the hub 402 and has a coaxial conductive metallic inner tubular portion 460 extending distally to couple to the assembly of the longitudinal dielectric structural portion 440 and the longitudinal conductive metallic structural portion 442. The coaxial conductive metallic inner tubular portion 460 rotates within the axial bore 458 of the outer tubular portion 456.

[0059] As can be best seen in Figures 12 and 14, the longitudinal conductive metal structural portion 442 carries an inner cutting window 425 having first and second circumferentially spaced cutting edges 448a, 448b, and has the dual function of functioning as a return electrode 455A even when in the window closed position of Figure 10, as further described below.

[0060] 12, the inner sleeve portion 415 is again shown separated from the outer sleeve assembly 410 and rotated 180° so that the electrode side ES faces downward and the window side WS is in an upward position. The longitudinal conductive metal structural portion 442 can be seen to carry the inner cutting window 425. Moreover, the longitudinal conductive metal structural portion 442 extends distally around the tip portion 462 of the inner sleeve portion 415, thus providing substantial hoop strength as the tip portion 462 distally surrounds the longitudinal dielectric structural portion 440 on the opposite side of the distal end 464 of the dielectric structural portion 440. As can be seen in FIG. 15, the proximal end 465 of the assembly of the longitudinal dielectric structural portion 440 and the longitudinal conductive metal structural portion 442 is sized for insertion into the axial channel or bore 466 of the thin-walled tubular portion 460 to complete the element of the inner sleeve portion 415. It can thus be seen how the tubular portion 460 having the axial channel or bore 466 slides over and engages the longitudinal dielectric structural portion 440 and the longitudinal conductive metal structural portion 442 to provide a strong connection about the proximal end 465 of the element. As can be best seen in Fig. 13, the sides 470a, 470b of the longitudinal dielectric structural portion 440 are configured to slide into receiving recesses or grooves 472a, 472b on either side of the open axial channel 474 in the longitudinal conductive metal structural portion 442, thereby locking the two portions 440 and 442 together.

[0061] FIG. 14 shows an exploded view of the components of FIG. 13 rotated 180°, with sides 470a, 470b of the dielectric structural portion 440 configured to be inserted into receiving grooves 472a, 472b on either side of an axial channel 474 of the longitudinal conductive metal structural portion 442.

[0062] 13 and 15, the electrical connections to the active electrode 445 and the return electrodes 455A, 455B can be described. In the exploded view of FIG. 13, it can be seen that an elongated electrical lead 475 is adapted to bend and be inserted into a pad recess 478 in the longitudinal dielectric structure portion 440 so as to extend longitudinally across the inner tubular portion 460 (FIG. 15). The electrical lead 475 is covered with an insulator (not shown) except for the pad portion 477. As can be readily appreciated, the active electrode 445 comprises a metal such as stainless steel, tungsten, or any other suitable conductive metal having first and second legs 478a, 478b adapted to be inserted through receiving channels 482a, 482b in the dielectric structure portion 440 that extend into the pad recess 478. Thus, it can be seen that the electrode 445 is cantilevered on the groove portion 484 of the dielectric structure portion 440, distal from the two receiving channels 482a, 482b in the dielectric structure portion 440. The pad portion 477 of the electrical lead 475 is then placed in contact with the legs 478a, 478b of the electrode 445 and soldered or otherwise electrically coupled within the recess 478. Finally, a potting material (not shown) is used to cover and fill the electrical pad portion 477 and the recess 478. Further, with reference to FIG. 15, it can be seen that the tubular portion 460 has a flattened surface 486 for receiving the electrical lead 475 as the tubular portion 460 and the axial channel or bore 466 therein slide over the dielectric structure portion 440 and the proximal end 465 of the conductive metal structure portion 442. 15, the flattened surface 486 of the tubular portion 460 allows an insulator layer 488 (such as a heat shrink material), shown in phantom, to cover the entirety of the tubular portion 460, the insulated electrical lead 475, the proximal end 465 and intermediate portion 490 of the dielectric structural portion 440, and the longitudinal conductive metal structural portion 442. This describes the electrical lead 475 that extends to the active electrode 445 carried within the dielectric structural portion 440.The proximal end (not shown) of the electrical lead 475 extends into the hub 402 (FIG. 10) and is then connected to electrical contacts in the motor-driven handpiece that enable rotation of the inner sleeve portion 415 and couples electrical energy to the electrical lead 475, as described in the previous embodiment.

[0063] As mentioned above, the longitudinal conductive structural portion 442 of the inner sleeve portion 415 (FIGS. 13, 15) includes the first return electrode 455A. However, the inner sleeve portion 415 does not carry an electrical lead to the longitudinal conductive structural portion 442. Rather, the outer sleeve assembly 410 of FIGS. 10, 11 and 12 includes an elongated metallic outer tubular portion 456 that includes an electrical conductor and is adapted to carry electrical current from the hub 402 to a distal end portion or distal housing 459 of the outer sleeve assembly 410. The longitudinal conductive metallic structural portion 442 of the inner sleeve portion 415 rotates tightly within an axial bore 458 of the outer tubular portion 456, such that the longitudinal conductive metallic structural portion 442, by virtue of its contact with the outer tubular portion 456, becomes the return electrode 455A. Thus, with reference to FIG. 12, the longitudinal conductive metallic structural portion 442 of the outer tubular portion 456 and the distal housing 459 are provided with a first return electrode 455A and a second return electrode 455B, respectively.

[0064] In another embodiment of the present invention, referring to Figures 15 and 16A, the active electrode 445 is dome-shaped with an outer surface 495 having a radius or curvature that is a segment of a cylinder such that the dome outer surface 495 of the electrode 445 is substantially aligned with the outer cylindrical surface 496 of the dielectric structural portion 440 and the outer surface 498 of the longitudinal conductive structural portion 442 when viewed in cross section (Figure 16A). The dome-shaped outer surface 495 of the electrode 445 is advantageous for contacting tissue because it protrudes outward as opposed to a flat surface electrode. Furthermore, the thicker dome-shaped central surface of the active electrode 445 results in much slower degradation and disintegration of the electrode 445 during extended use. Durability of the active electrode 445 is important for arthroscopic procedures where the electrosurgical element of the present invention can be used for many minutes. Referring to Figure 16A, the radius R1 of the outer surface 495 of the active electrode 445 is approximately equal to the radius R2 of the outer surface 496 of the dielectric structural portion 440. In one variation, the radius R1 of the outer surface 495 of the electrode 445 is 0.020 inches or less than the radius R2 of the outer surface 496 of the dielectric structural portion 440. Similarly, the radius R2 of the outer surface 496 of the dielectric structural portion 440 is approximately equal to the radius R3 of the outer surface 498 of the longitudinal conductive structural portion 442. In one variation, the radius R2 of the dielectric structural portion 440 is 0.020 inches or less than the radius R3 of the conductive structural portion 442. These dimensions are important to provide a tight rotational fit for the inner sleeve portion 415 within the outer tubular portion 456 and the axial bore 458 of the distal housing 459.

[0065] 16B and 16C, in one embodiment of the present invention, the longitudinal dielectric structural portion 440 is formed as a curved annular dielectric portion. The longitudinal conductive structural portion 442 can also be formed as a C-shaped annular portion or segment to form a wall 500 (having a metal wall portion 501a and a dielectric wall portion 501b) around an inner channel 502 communicating in an axial channel or axial bore 466 in the inner tubular portion 460 and a negative pressure source 420C for aspirating tissue particles and fluids from the working space, as known in the art. The annular dielectric structural portion 440 can be assembled with a C-shaped annular metal portion to form a generally tubular or cylindrical distal housing.

[0066] As will be further explained below, the dimensions and orientation of several elements associated with the active electrode 445, the dielectric structural portion 440, and the outer sleeve window 422 of the conductive structural portion 442 are important. In the variation shown in FIG. 16A, the active electrode 445 has an outer surface 495 that extends over a radial angle RA1 of at least 20°. Often, the outer surface 495 of the electrode 445 extends over a radial angle RA1 of at least 40°. In this variation, the transverse electrode cutting edges 504a and 504b are spaced apart at the interface 444 from the nearest surface of the conductive structural portion 442 by a radial angle RA2 of at least 10°, and often at least 20°. The minimum angle RA2 between the electrode cutting edges 504a, 504b and the interface 444 is necessary to provide optimal plasma ignition when using the probe in a plasma ablation mode.

[0067] 16A and 16B also show a minimum radial angle RA3 of the sidewall portions 505a and 505b of the conductive structural portion 442 that extend on either side of the inner window 425. This radial angle RA3 indicates the minimum height of such sidewall portions 505a, 505b from the recesses 506 between the teeth 508 (FIGS. 12 and 16A) to the interface 444 that provides an assembly of the dielectric structural portion 440 and the conductive structural portion 442 with the requisite strength during use. As can be seen in FIG. 16A, the metal sidewall portions 505a, 505b form the respective inner window cutting edges 448a, 448b, and the outer surfaces 498 of the sidewall portions 505a, 505b extend over a radial angle of at least 10°, and often at least 20°.

[0068] 16B, in another embodiment of the present invention, the important properties of the active electrode 445, the dielectric structural portion 440, and the longitudinal conductive structural portion 442 can be further described by certain dimensions at other radial angles. In one embodiment, the active electrode 445 has an outer surface 495 that extends circumferentially at least 0.030 inches. The metal sidewall portions 505a and 505b that form the cutting edges of the inner window 425 have an outer surface 498 that extends circumferentially a dimension D2 of at least 0.015 inches. Additionally, the transverse electrode cutting edges 504a and 504b of the electrode 445 are spaced apart from the nearest surface of the conductive structural portion 442 by a dimension D3 of at least 0.010 inches. In FIG. 16B, it can be seen that the dimension D3 is equal to the distance across the exposed outer surface 496 of the dielectric structural portion 440. Although active electrode 445 is shown in Figures 16A-16B and 17 with an outer surface 495 that is circumferentially symmetrical relative to dielectric structural portion 440 and inner window 425, it should be understood that electrode 445 may be circumferentially asymmetrical relative to dielectric structural portion 440 and / or inner window 425.

[0069] 16C, a cross-sectional, exploded view of the dielectric structural portion 440 and the conductive structural portion 442 is shown with a portion taken proximal to the window 425 (see FIG. 13). As seen in FIG. 16C, the wall 500 has an annular metal portion 501a and an annular dielectric portion 501b that extends radially around the longitudinal axis 406 and the inner channel 502. The metal wall portion 501a extends radially around the inner channel 502 at a radial angle RA4, typically of at least 120° or at least 180°. When the metal wall portion 501a extending at the radial angle RA4 as in FIG. 16C is described herein, it is meant to refer to the metal wall portion 501a that is proximal to the window 425. The size of the radial angle RA4 provides the necessary hoop strength to the conductive structural portion 442 and thus the distal end of the inner sleeve portion. In this variation, referring to FIG. 16C, the wall portion 501b of the dielectric structure portion 440 extends radially around the inner channel 502 adjacent the window 425 at a radial angle RA5 of at least 45° or at least 60°.

[0070] Referring now to Figure 17, another important aspect of the present invention can be described. As can be seen in Figure 17, the inner sleeve portion 415 has been stopped from rotation at a selected rotational position where the active electrode 445 carried by the dielectric structural portion 440 is centered in the cutting window 422 of the outer sleeve assembly 410. Although in this variation the outer sleeve window 422 is shown as having a sharp metal cutting edge without teeth or serrations, it should be understood that the outer sleeve window 422 could have any form of sharp teeth, serrations, etc. and still fall within the scope of the present invention.

[0071] It can also be seen in FIG. 17 that the longitudinal conductive structural portion 442 of the inner sleeve portion 415 is exposed at the outer sleeve window 422 when the outer sleeve assembly 415 is stopped in a rotational position where the electrode 445 is centered in the cutting window 422. As described above, the longitudinal conductive structural portion 442 of the inner sleeve portion 415 comprises a first return electrode 455A, and the distal portion of the housing 459 of the outer sleeve assembly 410 comprises a second return electrode 455B. FIG. 17 shows an RF current path CP that represents the shortest path for RF current between the active electrode 445 and the return electrode when operating in a conductive saltwater environment. As can be seen from FIG. 17, the shortest RF current path CP is from the active electrode 445 to the longitudinal conductive structural portion 442 (i.e., the first return electrode 455A) along the interface 444 of the dielectric structural portion 440 and the conductive structural portion 442. In other words, the shortest RF current path is not from the active electrode 445 to the cutting edges 450a and 450b of the outer window 422 in the distal housing 459 that constitutes the second return electrode 455B. In one embodiment of the present invention, the location of the interface 444 between the dielectric structural portion 440 and the conductive structural portion 442 at the selected rest position (or window closed position) is important to prevent the short current path CP to the cutting edges 450a and 450b of the outer window 422 (i.e., the second return electrode). If the substantial RF current path was direct from the electrode 445 to the cutting edges 450a, 450b, the RF plasma of the cutting edges would rapidly deteriorate and dull such sharp cutting edges 450a, 450b. Such dull cutting edges 450a, 450b of the outer sleeve window 422 in turn would reduce the cutting rate resulting from rotating or vibrating the inner sleeve portion 415 and the inner window 425 within the outer sleeve window 422.

[0072] In general, a surgical probe for ablating tissue in accordance with the present invention (FIGS. 10-17) comprises an elongate shaft extending about a longitudinal axis 406 with coaxial outer sleeve 410 and inner sleeve portion 415 having outer and inner cutting windows 422 and 425, respectively, at their distal ends, the inner sleeve portion having (i) a longitudinal dielectric wall portion carrying a first polarity or active electrode 445, and (ii) an electrically conductive structural portion 442 with sidewall portions 505a, 505b extending around the inner cutting window 425 with a first return electrode 455A, the active electrode 445 being spaced at least 0.010 inches from the sidewall portions 505a, 505b, as described above.

[0073] 17, a tissue ablation probe according to the present invention comprises an elongate shaft 405 extending about a longitudinal axis 406 and further comprises coaxial outer sleeve 410 and inner sleeve portion 415 having outer and inner cutting windows 422 and 425, respectively, at their distal ends, the inner sleeve portion 415 carrying therein a first polarity or active electrode 445 and a structure around the inner window 422 comprising a second polarity or return electrode 455A. In this variation, the structure at least partially surrounding the outer window 425 comprises the second polarity or return electrode.

[0074] In another aspect of the invention, referring again to Fig. 17, a surgical reset probe includes a windowed inner sleeve portion 415 rotatable within a windowed outer sleeve assembly 410, a controller 420A and a motor drive element configured to rotate the inner sleeve outer portion through windowed open and closed positions, and the controller 420A configured to stop the motor driven rotation of the inner sleeve outer portion at selected positions, where the active electrode 445 is positioned spaced apart from the cutting edges 450a and 450b (i.e., second return electrode 455B) of the outer sleeve window 422, and the first return electrode 455A is positioned intermediate the active electrode 445 and the cutting edges 450a and 450b (i.e., second return electrode 455B) of the outer sleeve window 422. This aspect of the invention can also be described by the dimensions of the surface of the inner sleeve portion relative to the outer window 422 of the outer sleeve 410. 16A, the radial angle RA1 of the electrode 445 and the radial angle RA2 of the dielectric structure portions 440 on either side of the electrode can combine to define a first radial angle, and the outer window 422 in the outer sleeve 410 defines a second radial angle indicated as RA6. In this embodiment, the second radial angle RA6 is greater than the combined radial angle defined by the surfaces of the electrode 445 and the dielectric structure portions 440 of the inner sleeve portion 415, and this radial angle can be rotated and then stopped within the outer window 425 of the outer sleeve 410. Typically, the radial angle RA6 of the outer window 422 is at least 90° or at least 135°.

[0075] 13-15, 16A and 16C, in another embodiment of the invention, an ablation probe 400 (FIG. 10) includes a windowed inner sleeve portion 415 rotatable within a windowed outer sleeve assembly 410, where a controller 420A (FIG. 10) and a motor drive unit are configured to rotate the inner sleeve portion 415 through windowed open and closed positions, a distal portion of the inner sleeve portion 415 includes a cylindrical wall 500 defining outer and inner surfaces 510 around an inner channel 502 (see FIGS. 16A, 16C). In FIG. 16C, it can be seen that the inner channel 502 is bounded by a first wall portion 501a having an inner surface 512a of the conductive structural portion 442 and a second wall portion 501b having an inner surface 512b of the longitudinal dielectric structural portion 440, each of the first and second wall portions 501a and 501b including the entire thickness of the cylindrical wall 500 and providing structural strength to the wall. This aspect of the invention allows for a maximum diameter of the inner channel 502 relative to the outer diameter of the assembly 430, such a larger inner channel facilitating fluid flow and tissue debris extraction. The above-described means of assembling the wall 500 is preferable over having a laminated wall, for example, with a metal inner sleeve and a dielectric outer sleeve or partial sleeve. As seen in FIG. 16C, the radii R and R' of the inner surfaces 512a and 512b, respectively, are approximately the same dimensions. Again, it should be understood that the term "wall" 500 as used herein describes the metal wall structure proximal to the window 425 or the dielectric structure facing the window.

[0076] 10-15, dielectric structure portion 440 can be seen to have a port 516 therein that underlies V-notch 518 in electrode 445. Port 516 is adapted for drawing fluid therethrough during RF energy delivery in an ablation mode that can reduce bubbles from the vicinity of active electrode 445 as plasma is generated. Additionally, FIGS. 10 and 17 show a port 520 in distal housing 459 of outer sleeve 410 to provide for fluid flow through the shaft assembly in the window closed position as shown in FIGS. 10 and 17 to maintain a constant outflow as opposed to an otherwise variable outflow with inner sleeve portion 415 rotating at high rotational speeds through the window open and window closed positions.

[0077] 18-19, another variant of the working end 525 of the probe is shown, more particularly the distal end of the inner sleeve portion 415' in exploded view, similar to the embodiment of FIGS. 10-16. The variant of FIG. 18 again includes a longitudinal dielectric structural portion 440' and a longitudinal conductive metal structural portion 442'. This variant differs from the previous embodiment shown in FIG. 13 in that the structure provided for firmly coupling the dielectric structural portion 440' and the conductive metal structural portion 442' together is different. As can be seen in FIGS. 18 and 19, the dielectric structural portion 440' has sidewall portions 540a, 540b extending in a partially cylindrical formation adapted to slidingly engage the inner surface 544 of the wall 545 of the longitudinal conductive metal structural portion 442'. As best seen in Fig. 19, the sidewall portions 540a and 540b of the dielectric structural portion 440' have an outer surface 548 with a radius RR that matches the inner surface 544 and radius RR of the conductive metal structural portion 442'. It can therefore be seen that a secure and durable connection can be provided between the dielectric structural portion 440' and the conductive metal structural portion 442' by axially sliding the dielectric structural portion 440' into a longitudinal opening or channel 550 in the conductive metal structural portion 442'. In Fig. 19, the radial angle RA1 of the surface of the electrode 445, the radial angle RA2 of a portion of the dielectric structural portion 440', and the radial angle RA3 of the wall portion of the conductive metal structural portion 442' can be the same as those described above.

[0078] In FIG. 20, another variation of the working end 600 of the inner sleeve portion 615 is provided in an exploded view to show the components adapted to securely connect the longitudinal dielectric structural portion 620 to the longitudinal metal structural portion 622. In this variation, the lateral edges 624a and 624b of the dielectric structural portion 620 do not interlock with the lateral edges 628a and 628b of the metal structural portion 622 or overlap as in the previous variation. As can be seen from FIGS. 20 and 21, the interfaces of the lateral edges of the structural portions 620, 622 simply abut one another and are secured together by a retaining collar 640 adapted to fit into an annular notch or recess 644 in the dielectric structural portion 620 to securely hold the elements together. As will be appreciated, the metal retaining collar 640 may have a discontinuity or gap 648 in its circumference to allow the collar to slide over the structural portions 620 and 622 into the recesses 644 under tension. The gap 648 in the collar 640 may then be welded, thus permanently joining the dielectric structural portion 620 and the metal structural portion 622 .

[0079] In the variation shown in FIG. 20, an active electrode 650 having legs 652a, 652b can be seen to be similar to that previously described in FIGS. 13-15. In FIG. 20, legs 652a, 652b can be seen to extend into receiving channels 654a and 654b in the dielectric structure portion 620. The electrical lead 660 in FIG. 20 again has a pad element 662 received by a recess 664 in the dielectric structure portion 620 for contacting an electrical lead 665 therein. In this variation, the electrical lead 655 in the recess 664 is bare and in electrical contact with the pad element 662, but is covered with an insulator 668 where such lead extends through the dielectric structure portion 620 and contacts the legs 652a and 652b of the electrode 650. In all other respects, the assembly of components in FIG. 20 functions similarly to that previously described.

[0080] 22-26, another variation of the probe 700 is shown, in which the hub 702 and shaft 705 (see FIG. 25A) are centered on a longitudinal axis 706 and extend to a working end 708 as shown in FIG. 22. FIG. 22 shows the distal portion of the outer sleeve assembly 710 and the axial bore 712 therein, along with the inner sleeve portion 715. FIG. 23 shows the inner sleeve portion 715 from a different angle to better show the electrical leads 718 carried by the inner sleeve. Referring now to FIG. 24, an exploded view of the inner sleeve portion 715, it can be seen that the longitudinal dielectric structural portion 720 is again secured to the longitudinal metallic structural portion 722 and coupled to the tubular portion 724 with a retaining collar 725. Such a retaining collar 725 used to secure the dielectric structural portion 720 and the metallic structural portion 722 together can be similar to that described in the embodiment of FIG. 20.

[0081] 24, this variation differs from the previous embodiment in that the electrical lead 718 extends through a recess 730 in the dielectric structural portion 720 and couples to the leg 732 of the active electrode 735. The electrical lead 718 is not carried on the outer surface of the tubular portion 724. Instead, the electrical lead 718 extends through an internal bore 742 of the tubular portion to the active electrode 735. As seen in FIG. 22, the electrical lead 718 extends proximally from the electrode 735 and is bent at a bend 744 to enter the internal bore 742 of the inner tubular portion 724 and, in this variation, extends through a hypotube 745 which is coupled to the wall of the tubular portion 740. It can be seen that a slot 748 is provided in the wall of the tubular portion 724 which allows for welding the hypotube 745 to the inner surface of the bore 742 in the tubular portion 724. At least one similar slot (not shown) may be provided along the length of the tubular portion 724 to secure the hypotube 745 in place. It has been found important to carry the electrical lead 718 within the interior bore 742 of the tubular portion 724 to protect it from potential damage. In the previous embodiment, for example in the version of FIG. 15, the electrical lead 475 was extended along the exterior surface of the inner tubular portion 460 into a flat surface 486 and then covered with an insulation layer 488. In the previous embodiment of FIG. 15, as the shaft 405 of the probe 400 (FIG. 10) is torqued and can be bent significantly during a procedure, the high speed rotation of the inner sleeve portion 415 had the potential to wear and deteriorate the insulation sleeve 488 covering the electrical lead 425 which could cause an electrical short. Thus, one embodiment of the invention as shown in Figures 22-24 includes carrying electrical lead 718 in an interior bore 742 of metal tubular portion 724 to ensure that bending or torque on shaft 705 cannot damage electrical lead 718 while operating inner sleeve portion 715 at high rotational speeds. Figures 22 and 24 also show an annular bushing 746 adapted to cover recess 730 which is filled with potting material as previously described. Referring again to Figure 22, there is a heat shrink insulator sleeve 749 covering at least a portion of tubular portion 724 and bushing 746.Thus, at high speeds, insulator sleeve 749 and bushing 746 are the bearing surfaces for inner sleeve portion 715 as it rotates within outer sleeve 710 .

[0082] 22-24, it can be seen that the inner tubular portion 724 and hypotube 745 comprise a return electrode 750 having conductive saline flowing through an inner channel 755 of the tubular portion 724. Thus, it is apparent that the electrical lead 718 carries its own substantial insulating layer on its surface. In one variation, the electrical lead 718 is a copper wire, platinum wire, or the like, instead of a stainless steel wire, since stainless steel wires are resistively heated. In one aspect of the invention, the electrical lead 718 is made of a material that is not resistively heated, since the electrical lead 718 would heat the saline effluent traveling through the channel 755, undesirably increasing the temperature of the handpiece.

[0083] 25A and 25B, a perspective view and cutaway view of the hub 702 are shown. FIG. 26 is an enlarged cutaway view of the interior portion of the hub 702. As seen in FIG. 25B and 26, the hypotube 745 carries the electrical lead 718 that extends through the inner tubular portion 724. As seen in FIG. 25B, the tubular portion 724 extends through the hub 702 and the hypotube 745 has a proximal end 758 inside the hub. The proximal end 760 of the electrical lead 718 curves outward through a slot 762 in the tubular portion 724 and then extends into an interface 765 between two polymer collars 766 and 768 that together provide a seal over and around the insulating layer on the electrical lead 718. A heat shrink material 769, such as FEP, can then be placed over the collars 766 and 768 (FIG. 26). In Figures 25B and 26, it can be seen that a polymeric coupling sleeve 770 is secured to a proximal end portion 772 of the tubular portion that extends proximally to a drive coupler 774 adapted to couple to a motor drive element of a handpiece (not shown). Figures 25B and 26 further show that a conductive metal contact ring 775 is disposed over the insulating coupling sleeve 770. As seen in Figure 26, proximal to the contact ring 775 is another polymeric collar 776 that is again covered with FEP or other heat shrink material. Still referring to Figure 26, the proximal end 777 of the electrical lead 718, with its insulation layer removed, contacts and is electrically coupled to the rotating contact ring 775. The contact ring 775 then mates with spring loaded ball contacts 780a and 780b in the handpiece (not shown) to carry RF current from the RF source 720B to the active electrode 735 (Figure 22). Spring loaded ball contacts 782a and 782b in the hub are adapted to carry the current to or from the outer sleeve assembly 710 which comprises the return electrode. Of course, conductive fluid can migrate to various parts of the hub 702 and it is necessary to prevent any migration of conductive fluid to the interface between the spring loaded ball contacts 780a and 780b and the rotating contact ring 775. Any migrating conductive fluid is effectively the return electrode and could cause a short circuit.To ensure that there is no moving conductive fluid contacting contact ring 775, Figures 25B and 26 illustrate a flexible seal 785 having flexible annular sealing elements 788a and 788b both proximal and distal from the rotating contact ring 775. By this means, the chamber 790 where the spring loaded ball contacts 780a and 780b engage the contact ring 775 remains fluid tight.

[0084] Although specific embodiments of the present invention have been described in detail above, it should be understood that this description is for illustrative purposes only and that the above description of the present invention is not exhaustive. Certain features of the present invention are shown in some drawings and not in others, and this is for convenience only, and any feature can be combined with other features according to the present invention. Many variations and alternatives will be apparent to those of ordinary skill in the art. Such alternatives and modifications are intended to be included within the scope of the claims. Certain features presented in the dependent claims can be combined and still fall within the scope of the present invention. The present invention also encompasses embodiments as if the dependent claims were alternatively written in a multiple dependent claim format with reference to other independent claims.

[0085] Other variations are within the spirit of the invention. Thus, while the invention is susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been described above in detail. It is to be understood, however, that there is no intention to limit the invention to the particular forms disclosed, but on the contrary, the invention is intended to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the appended claims.

[0086] Use of the terms "a" and "an" and "The" and similar referents in the context of describing the present invention (particularly in the context of the accompanying claims) should be construed to include both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprise", "have", "include" and "comprise" should be construed as open-ended terms (i.e., meaning "including, but not limited to"), unless otherwise indicated. The term "connected" should be construed as being partially or wholly contained within, attached to, or joined together, even if there is something intervening. The recitation of numerical ranges herein is intended merely to serve as a shorthand method for individually referring to each value falling within the range, unless otherwise indicated herein, and each value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "etc.") provided herein is intended merely to further clarify embodiments of the invention and does not limit the scope of the invention unless specifically claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0087] Preferred embodiments of the present invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of these preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect that skilled artisans will apply such variations as appropriate, and intend to practice the invention otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, all combinations of the above-described elements in all possible variations thereof are encompassed by the present invention unless otherwise indicated herein or clearly contradicted by context.

[0088] All references cited in this specification, including publications, patent applications, and patents, are herein incorporated by reference to the same extent as if each reference was specifically and individually indicated to be incorporated by reference and that the contents of each were set forth in full herein. The present invention has the following configurations. [Configuration 1] 1. A tissue ablation device comprising: an outer sleeve extending along a longitudinal axis from a proximal end to a distal end and having an axial bore opening to an outer window adjacent said distal end; an inner sleeve rotatably received within the axial bore of the outer sleeve and having an axial channel adapted to communicate with a source of negative pressure; a distal housing attached to a distal end of the inner sleeve, the distal housing having an annular dielectric portion and a circumferentially adjacent annular metallic portion, the annular metallic portion including inner windows having circumferentially spaced sharp cutting edges opening into the axial channel; an active electrode carried by the annular dielectric portion; A tissue ablation device, wherein the inner window is circumferentially spaced from the active electrode, and the inner window and the active electrode rotate alternately in alignment with the outer window as the inner sleeve rotates within the outer sleeve. [Configuration 2] 2. The tissue excision device of configuration 1, wherein the outer window in the outer sleeve is circumferentially wider than the annular dielectric portion of the distal housing, the annular dielectric portion being capable of stopping within the outer window leaving a margin portion of the annular metal portion exposed between the annular dielectric portion and at least one edge of the outer window, the exposed annular metal portion acting as a return electrode to prevent current concentration at the at least one edge of the outer window. [Configuration 3] 2. The tissue excision device of configuration 1, wherein the annular metallic portion and the annular dielectric portion, in cross section, extend 360 degrees around the distal housing proximal to the inner window. [Configuration 4] 2. The tissue ablation device of configuration 1, wherein the outer side of the active electrode extends in an arc of at least 20° in cross-section and the outer side of the annular dielectric portion extends in an arc of at least 10° on each side of the active electrode in cross-section. [Configuration 5] 5. The tissue excision device of configuration 4, wherein the distance between each sharp cutting edge of the annular metallic portion and the annular dielectric portion extends over an arc of at least 10 degrees. [Configuration 6] 2. The tissue excision device of configuration 1, wherein the active electrode and an outer surface of the annular dielectric portion extend across a first arc in a cross-section, and the outer window of the outer sleeve extends across a second arc in a cross-section, the second arc being larger than the first arc. [Configuration 7] 7. The tissue ablation device of claim 6, wherein the active electrode has an outer surface extending circumferentially at least 0.762 mm. [Configuration 8] 8. The tissue ablation device of configuration 7, wherein the active electrode edge is spaced from the nearest surface of the annular metallic portion by at least 0.254 mm. [Configuration 9] 2. The tissue ablation device of configuration 1, wherein an outer surface of the active electrode has a radius R1, an outer surface of the annular dielectric portion has a radius R2, and an outer surface of the annular metallic portion has a radius R3. [Configuration 10] 10. The tissue excision device of claim 9, wherein the radius R1 is less than the radius R2 by 0.508 mm or less. [Configuration 11] 11. The tissue excision device of claim 10, wherein the radius R2 is less than the radius R3 by 0.508 mm or less. [Configuration 12] 2. The tissue ablation device of claim 1, wherein the active electrode has an outer surface diametrically opposite the inner window. [Configuration 13] 2. The tissue ablation device of claim 1, wherein the active electrode has an outer surface that asymmetrically faces the inner window. [Configuration 14] 2. The tissue excision device of claim 1, wherein the sharp cutting edge comprises a feature selected from a set of straight cutting edges, serrated cutting edges, and toothed cutting edges. [Configuration 15] 2. The tissue excision device of claim 1, wherein the distal housing comprises an electrically conductive generally tubular structure having an axial channel and a dielectric insert disposed within the axial channel. [Configuration 16] 16. The tissue ablation device of aspect 15, wherein the distal housing further comprises an active electrode insert disposed in a groove in an outer surface of the dielectric insert. [Configuration 17] 2. The tissue ablation device of claim 1, further comprising an elongated electrical conductor disposed within the axial bore of the inner sleeve and having a distal end attached to the active electrode. [Configuration 18] 18. The tissue excision device of embodiment 17, wherein the electrical conductor is within a protective tube supported within the axial bore of the inner sleeve. [Configuration 19] 2. The tissue excision device of configuration 1, further comprising a proximal hub, the outer sleeve being fixedly attached to the proximal hub and the inner sleeve being rotatably attached to the proximal hub. [Configuration 20] 1. A tissue ablation system comprising: 19. A tissue excision device according to claim 18, a handpiece configured to removably connect to the proximal hub; The handpiece comprises: (a) a motor drive unit adapted to rotate the inner sleeve and the inner window relative to the outer window through a window-open position and a window-closed position; (b) a controller configured to selectively drive a motor to rotate the inner sleeve, stop the motor driven rotation of the inner sleeve, deliver an ablation current to the active electrode, and deliver a cauterization current to an active electrode; and A tissue ablation system comprising: [Configuration 21] 1. A method of treating tissue, comprising: Providing a tissue excision device according to aspect 20; engaging the outer window of the outer sleeve at a target tissue site; operating the controller to rotate the inner sleeve and the inner window relative to the outer window to mechanically cut tissue with the sharp cutting edge; A method for treating tissue having [Configuration 22] 22. The method of treating tissue of embodiment 21, wherein the tissue to be resected includes at least one of soft tissue and bone. [Configuration 23] 22. The method of treating tissue described in configuration 21, further comprising the steps of operating the controller to stop rotation of the inner sleeve with the active electrode aligned with the outer window and supplying an ablation current to the active electrode to ablate tissue. [Configuration 24] 23. The method of treating tissue of embodiment 22, wherein the tissue to be ablated comprises soft tissue. [Configuration 25] 23. The method of treating tissue of claim 22, further comprising the steps of operating the controller to stop rotation of the inner sleeve with the active electrode aligned with the outer window and supplying an ablation current to the active electrode to ablate tissue. [Configuration 26] 22. The method of treating tissue according to claim 21, further comprising: supplying an ablation current to the active electrode while the inner sleeve is rotated such that the inner window ablates tissue and the active electrode ablates tissue. [Configuration 27] 27. The method of treating tissue of embodiment 26, wherein the tissue comprises soft tissue. [Configuration 28] 27. The method of treating tissue according to embodiment 26, wherein the tissue comprises bone tissue.

Claims

1. 1. A tissue ablation device comprising: an outer sleeve extending along a longitudinal axis from a proximal end to a distal end and having an axial bore opening to an outer window adjacent said distal end; an inner sleeve rotatably received within the axial bore of the outer sleeve and having an axial channel adapted to communicate with a source of negative pressure; a distal housing attached to a distal end of the inner sleeve, the distal housing having an annular dielectric portion and a circumferentially adjacent annular metallic portion, the annular metallic portion including inner windows having circumferentially spaced sharp cutting edges opening into the axial channel; a first longitudinal portion having the annular dielectric portion; a second longitudinal portion having the annular metal portion, the first longitudinal portion being coupled to the second longitudinal portion, a proximal end of the assembly of the first longitudinal portion and the second longitudinal portion being dimensioned for insertion into the axial channel of the inner sleeve, the inner sleeve engaging the first longitudinal portion and the second longitudinal portion to provide a connection about the proximal end of the assembly; an active electrode carried by the annular dielectric portion; A tissue ablation device, wherein the inner window is circumferentially spaced from the active electrode, and the inner window and the active electrode rotate alternately in alignment with the outer window as the inner sleeve rotates within the outer sleeve.

2. A tissue excision device as described in claim 1, wherein the outer window in the outer sleeve is circumferentially wider than the annular dielectric portion of the distal housing, the annular dielectric portion can be terminated within the outer window leaving a margin portion of the annular metal portion exposed between the annular dielectric portion and at least one edge of the outer window, and the exposed annular metal portion acts as a return electrode to prevent current concentration at the at least one edge of the outer window.

3. The tissue excision device of claim 1 , wherein the annular metallic portion and the annular dielectric portion, in transverse cross section, extend 360° around the distal housing proximal to the inner window.

4. 2. The tissue ablation device of claim 1, wherein the outer surface of the active electrode extends in a cross-sectional arc of at least 20 degrees and the outer surface of the annular dielectric portion extends in a cross-sectional arc of at least 10 degrees on each side of the active electrode.

5. The tissue excision device of claim 4 , wherein the distance between each sharp cutting edge of the annular metallic portion and the annular dielectric portion extends over an arc of at least 10°.

6. 2. The tissue excision device of claim 1, wherein the active electrode and an outer surface of the annular dielectric portion extend across a first arc in a cross-section and the outer window of the outer sleeve extends across a second arc in a cross-section, the second arc being larger than the first arc.

7. The tissue ablation device of claim 6 , wherein the active electrode has an outer surface extending circumferentially at least 0.762 mm.

8. The tissue excision device of claim 7, wherein the lateral electrode cutting edge of the active electrode is spaced at least 0.254 mm from the nearest surface of the annular metal portion.

9. The tissue ablation device of claim 1 , wherein an outer surface of the active electrode has a radius R1, an outer surface of the annular dielectric portion has a radius R2, and an outer surface of the annular metallic portion has a radius R3.

10. The tissue excision device of claim 9 , wherein the radius R1 is less than the radius R2 by no more than 0.508 mm.

11. The tissue excision device of claim 10 , wherein the radius R2 is less than the radius R3 by no more than 0.508 mm.

12. The tissue ablation device of claim 1 , wherein the active electrode has an outer surface diametrically opposed to the inner window.

13. The tissue ablation device of claim 1 , wherein the active electrode has an outer surface that asymmetrically faces the inner window.

14. The tissue excision device of claim 1 , wherein the sharp cutting edge comprises a feature selected from a set of straight cutting edges, serrated cutting edges, and toothed cutting edges.

15. The tissue excision device of claim 1 , wherein the second longitudinal portion comprises an electrically conductive generally tubular structure having an axial channel, and the first longitudinal portion has a dielectric insert disposed within the axial channel.

16. The tissue excision device of claim 15, wherein the generally tubular structure and the dielectric insert have engaging longitudinal surfaces, the longitudinal surfaces extending along an interface between the generally tubular structure and the dielectric insert.

17. The tissue ablation device of claim 15 , wherein the active electrode further comprises an active electrode insert disposed in a groove in an outer surface of the dielectric insert.

18. The tissue excision device of claim 17, wherein the active electrode insert has at least a first leg that is received in a receiving channel of the dielectric insert.

19. The tissue excision device of claim 1 , further comprising an elongated electrical conductor disposed within the axial bore of the outer sleeve and having a distal end attached to the active electrode.

20. 20. The tissue excision device of claim 19, wherein the electrical conductor is within a protective tube supported within the axial bore of the inner sleeve.

21. The tissue resection device of claim 1 , further comprising a proximal hub, the outer sleeve being fixedly attached to the proximal hub and the inner sleeve being rotatably attached to the proximal hub.

22. 1. A tissue ablation system comprising:

22. The tissue excision device of claim 21 ; a handpiece configured to removably connect to the proximal hub; The handpiece comprises: (a) a motor drive unit adapted to rotate the inner sleeve and the inner window relative to the outer window through a window-open position and a window-closed position; (b) a controller configured to selectively drive the motor drive unit to rotate the inner sleeve, stop the motor driven rotation of the inner sleeve, deliver an ablation current to the active electrode, and deliver a cauterization current to the active electrode; and A tissue ablation system comprising:

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