Patent Description:
To promote efficiency, endoscopic tool systems including a reusable handpiece and a selection of interchangeable tool probes having different working ends have been proposed. Such working ends may each have two or more functionalities, such as soft tissue removal and hard tissue resection, so such tools systems can provide dozens of specific functionalities, providing great flexibility.

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 resecting 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 deliver an electrical current to cauterize bleeding tissue resulting from ablation, cutting, or other trauma during a procedure.

One problem, however, with such combined mechanical/electrosurgical ablation probes is that the delivery of an ablation current from the ablation electrode can degrade the mechanical cutting blade. Such degradation is a particular problem with sharp metal cutting edges where the inventors herein have found that the ablation current can focus on the sharp metal cutting edges, quickly rendering them unsuitable for cutting hard tissues.

It is therefore an object of the present invention to provide improved surgical systems such as improved arthroscopic tissue cutting and removal system wherein a motor-driven electrosurgical device is provided for cutting and removing bone or soft tissue from a joint or other site. It is a further object of the present invention to provide combined mechanical/electrosurgical cutters where degradation of the mechanical cutting element is reduced or eliminated. In particular, it would be desirable to provide metal cutters having cutting windows with sharp cutting edges which can be exposed to both ablation and cauterizing currents without loss to ability to mechanically cut hard tissues, such as bone. At least some of these objectives will be met by the inventions described herein.

<CIT> discloses an arthroscopic cutting probe including an outer sleeve having a longitudinal bore and an outer cutting window at its distal end. <CIT> discloses an electrosurgical device having a tubular outer shaft and an inner shaft.

The present invention provides a device as defined in claim <NUM>.

Methods are described herein but the methods are not claimed.

The device may provide a combination mechanical resection and electrosurgical treatment probe suitable for arthroscopic and other endoscopic and minimally invasive medical procedures. In particular, the probe may include a rotating inner sleeve member with a distal inner window having sharp metal cutting edges that is rotatable in an outer sleeve having a distal outer window with cooperating sharp metal edges. The rotating inner sleeve member will typically have a tubular configuration and have a vacuum-assisted extraction channel therethrough. An active electrosurgical electrode is carried on the rotating inner sleeve, typically located at or near a location at or near the distal end which opposes the inner window. In a method of use, rotation of the inner sleeve member can be stopped to position and expose the active electrosurgical electrode in the outer window of the outer sleeve. The active surgical electrode is used to selectively deliver ablation current as well as cauterizing current. Delivery of an ablation current when the active surgical electrode is in proximity to the sharp metal edges of the outer window has been found by the inventors herein to present a substantial risk of degrading the sharp outer window edges due to a concentrated current flux at such sharp edges. The inventors herein, however, have further found that the sharp metal edges of the outer window can be protected and preserved by locating a return electrode surface on the rotating inner sleeve member where the return electrode surface is positioned between the ablation electrode and sharp edges of the outer window when the active surgical electrode is positioned (typically rotationally center) within the outer cutting window. In particular, by locating the return electrode surface on the inner sleeve member so that it is closer to the ablation electrode than to an outer window edge (while maintaining a sufficient distance to allow bipolar current flow in the treatment environment), the return current can be preferentially directed to the inner sleeve's return electrode surface with less current being received by the metal edges of the outer window which form a return electrode surface. In this way, the inventors herein believe that current concentrations at the sharp edges of the outer window may be sufficiently reduced to lessen or eliminate degradation of such sharp edges. Such sharpened outer window edges are at high risk of degradation at least in part due to current concentration that is found on all sharp metal edges. By directing the return current to a return electrode surface which is generally free from such current-concentrating features, and away from the outer window edges, the sharpness of the outer window edges can be preserved.

In particular embodiments, the outer window in the outer sleeve is circumferentially wider than the annular dielectric portion of the distal housing so that the annular dielectric portion may be stopped within the outer window leaving marginal portions of the annular metal portion exposed between the annular dielectric portion and at least one edge of the outer window so that the exposed annular metal portion acts as a return electrode preventing current concentration at the at least one edge of the outer window. That is, the return electrode defined by the annular metal portion of the distal housing will preferentially collect current from the active electrode since the return electrode is closer to and larger than the edge of the outer window, thus limiting or eliminating damage to the edge of the outer window that might otherwise occur if the edge acted as a primary return electrode.

In further embodiments, the annular metal portion and the annular dielectric portion will extend a full <NUM>° about a transverse cross-section of the distal housing portion that is proximal to the inner window. In specific instances, the electrode will be mounted on the annular dielectric portion (typically in a channel or recess so that an outer surface of the active electrode will follow the same outer curvature as the annular dielectric portion) and have a surface that extends over an arc in a range of at least about <NUM>° of the transverse cross-section, while the annular dielectric portion has surfaces extending over an arc on each side of the electrode in a range of at least <NUM>° of the transverse cross-section, and the annular metal portion has side walls on each side of the inner window extending over an arc in a range of at least <NUM>° of the transverse cross-section.

In further instances, a distance between each sharp cutting edge of the annular metal portion and the adjacent annular dielectric portion extends over an arc of at least <NUM>°. Such a distance assures that the active electrode and the adjacent return electrode are separated by minimum distance to allow optimal bipolar operation. Typically, the surface of the active electrode will span a circumferential distance of at least <NUM> inches (i.e. <NUM>), and the active electrode edges are spaced-apart from the closest surface of the annular metal portion (which forms return electrode) at least <NUM> inches (i.e. <NUM>).

In other exemplary embodiments, the cross-section of the distal housing and the region of the active electrode, dielectric surface and return electrode, will have a generally circular cross-section, with the active electrode having a radius R1, the outer surface of the annular dielectric portion having a radius R2, and the outer surface of the annular metal portion having a radius R3. Typically, R1 would be less than R2 by a distance of <NUM> inches (i.e. <NUM>) or less and R2 may be less than R3 by a distance of <NUM> inches (i.e. <NUM>) or less. Such small differences allow the electrode and the annular dielectric portion to be slightly inset relative to the cylindrical surface of the annular metal portion, reducing the risk of wear and degradation to the active electrode during rotation.

In particular embodiments of the tissue resecting device of the present invention, the active electrode has an outer surface that is diametrically opposed to the inner window formed in the annular metal portion of the distal housing. The dielectric portion is also diametrically opposed to the inner window. During use of the device, a controller is configured to stop rotation of the inner sleeve to position and expose the electrode and dielectric portion in the outer window of the outer sleeve. By providing a selected circumferential spacing between the active electrode and the sharp edges of the outer window, and positioning the return electrode portion of the inner sleeve in that space, degradation of the sharp edges of the outer window is minimized. In particular, locating the surface area of the return electrode formed by the annular metal portion between the active electrode and the sharp metal edges of the outer window reduces the current concentration experienced by the outer window edges. 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 located relative to the inner window in other embodiments so long as, when the inner sleeve is in a stopped position, a sufficient available return electrode area of the inner sleeve is maintained between the active electrode and the outer window's sharp edges.

In other specific embodiments of the tissue resecting devices of the present invention, the sharp cutting edges on the inner window may be in the form of linear edges, serrated edges, edges having cutting teeth formed therein, and any other form of cutting edge known to be effective with tissues of all types, particularly with hard tissues, such as bone.

In still other specific aspects of the tissue resecting device of the present invention, the distal housing may comprise an electrically conductive tubular structure having an axial channel formed in a wall thereof. A dielectric insert may be disposed in the axial channel to form the annular dielectric portion where the annular metal portion of the distal housing is provided by the adjacent wall of the electrically conductive tubular structure.

For reference, the device may be used for a method of resecting tissue comprising providing a probe with an elongated shaft having co-axial outer and inner sleeves with outer and inner resecting windows in their respective distal ends. The inner sleeve member is rotatable in the outer sleeve, and the inner sleeve member carries active and return electrodes. The inner and outer resecting windows are engaged against tissue while rotating or rotationally oscillating the inner sleeve member to thereby resect tissue, and RF current is delivered to the active electrode the electrode to apply energy to tissue. An ablation RF current can be delivered with the inner sleeve in its stopped position to ablate tissue in a first mode. A coagulation RF current can be delivered with the inner sleeve in its stopped position to coagulate bleeding tissue in a second mode. Also, a coagulation RF current can be delivered with the inner sleeve rotating to contemporaneously resect and coagulate tissue in a third mode.

In such instances, an elongate electrical conductor may be disposed in the axial bore of the inner sleeve and can be connected in a distal end to the active electrode and have a proximal end which can be connected to an electrosurgical power source, typically in a hub as described in more detail below.

In further instances, a proximal hub may be attached to the tissue resecting device, typically being fixedly attached to a proximal end of the outer sleeve and rotatably attached to a proximal end of the inner sleeve. The proximal hub will typically be removably connectable to a handle or other handheld unit having a motor configured to rotate the inner sleeve member relative to the outer sleeve and the proximal hub.

The present invention also provides tissue resecting systems comprising any tissue resecting devices as described previously in combination with a handle other handheld unit particularly those tissue resecting devices having a proximal hub configured to rotate the inner sleeve member relative to the outer sleeve and to provide electrical connections to the active electrode and return electrodes. Such tissue resecting systems may further comprise a handpiece configured to removably connect to the proximal hub. The handpiece will typically include a motor drive adapted to rotate the inner sleeve member and an inner window relative to an outer window in the outer sleeve through window-open and window-closed positions. A controller may also be provided in the handle or other handheld unit, where the controller is adapted to selectively drive the motor to rotate the inner sleeve, to stop the motor-driven rotation of the inner sleeve, to deliver ablation current to the active electrode, and to deliver cauterizing current to the active electrode, either individually or in various combinations.

For reference, such a tissue resecting system may be used for methods comprising engaging the outer window of the outer sleeve against a target tissue site and operating the controller to rotate the inner sleeve member and the inner window relative to the outer window to mechanically resect tissue with the sharp cutting edges. While any tissue may be resected, the sharp cutting edges are particularly effective for resecting soft tissue and bone.

The methods further comprise operating the controller to stop rotation of the inner sleeve member with the active electrode aligned in the outer window of the outer sleeve and to deliver an ablation current to the active electrode to ablate tissue. While any type of tissue may be ablated, a radiofrequency and related forms of electrosurgical ablation are particularly effective with soft tissue.

By having mechanical tissue resection available for treating hard tissues such as bone as well as electrosurgical tissue ablation available for treating soft tissue, the same device can be conveniently used to treat both bone and soft tissues 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 an initial procedure has been completed with a first probe or tool.

In yet a further aspect, the tissue resecting probe of the present invention will have seals on proximal and distal sides of electrical contact(s) in hub. For example, the proximal hub may be coupled to an elongated outer sleeve extending about a longitudinal axis where a housing of the hub has a distal end with an opening therein. A rotatable inner sleeve member may be configured to rotate in the hub and outer sleeve, where the inner sleeve member extends to a working end passing through the opening. The inner sleeve member may carry an electrical contact ring adapted to rotatably contact a non-rotating electrical contact in an interior of the hub, and first and second annular seals may be carried by the hub which contact and seal the inner sleeve member on proximal and distal sides of the contact ring to provide a fluid-tight seal around the contact ring and non-rotating contact.

In specific instances, the contact ring may be coupled by an electrical lead to an active electrode carried in said working end of the inner sleeve, and the electrical lead may be carried in a passageway inward of a wall of the inner sleeve. The electrical lead may be positioned on an outer wall or within the axial bore of the inner sleeve member to complete a current path. The hub may be configured for detachable coupling with a receiving channel in a handpiece carrying a motor drive, and the receiving channel may carry an active contact adapted for electrically coupling with the 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 for RF current to a return electrode carried by the outer sleeve.

In a still further aspect, the distal housing of the present invention has a continuous (usually circular) wall having a thickness in a radial direction. A first portion of the wall, typically an annular segment, has a full wall thickness which entirely metal, and a second portion of the wall, typically an annular segment, has a full wall thickness which is entirely ceramic in the radial direction, i.e., the wall structure is not layered which would increase wall thickness and reduce the cross-sectional area available for the axial bore needed to accommodate tissue debris extraction.

For example, the tissue resecting probe may comprise an elongated outer sleeve extending about a longitudinal axis with a distal portion having an outer window that opens to an axial bore therein. An inner sleeve member may be configured to rotate in the bore, and the inner sleeve member may include a distal housing assembly having an inner window that opens to an interior channel. The housing assembly may include a metal wall portion and a ceramic or other dielectric wall portion defining said interior channel, where the full wall thickness along any radial vector is either metal or dielectric, typically a ceramic. Typically, an inner surface of the dielectric wall portion will comprise a surface of the interior channel. An outer surface of the dielectric wall portion may carry an electrode, and the metal wall portion may define lateral cutting edges of the inner window.

Various embodiments of the present invention will now be discussed with reference to the appended drawings. It should be appreciated that the drawings depict only typical embodiments of the invention and are therefore not to be considered limiting in scope.

The present invention relates to bone cutting and tissue removal devices. Several variations of the invention will now be described to provide an overall understanding of the principles of the form, function and methods of use of the devices disclosed herein. In general, the present disclosure provides for 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 are configured for detachable coupling to a non-disposable handpiece that carries a motor drive component. This description of the general principles of this invention is not meant to limit the inventive concepts in the appended claims.

In one variation shown in <FIG>, the arthroscopic system <NUM> of the present invention provides a handpiece <NUM> with motor drive <NUM> and a disposable shaver assembly or probe <NUM> with a proximal hub <NUM> that can be received by receiver or bore <NUM> in the handpiece <NUM>. In one aspect, the probe <NUM> has a working end <NUM> that carries a high-speed rotating cutter that is configured for use in many arthroscopic surgical applications, including but not limited to treating bone in shoulders, knees, hips, wrists, ankles and the spine.

In <FIG>, <FIG> and <FIG>, it can be seen that probe <NUM> has a shaft <NUM> extending along longitudinal axis <NUM> that comprises an outer sleeve <NUM> and an inner sleeve member <NUM> rotatably disposed therein with the inner sleeve member <NUM> carrying a distal ceramic cutting member <NUM> (<FIG>). The shaft <NUM> extends from the proximal hub <NUM> wherein the outer sleeve <NUM> is coupled in a fixed manner to the hub <NUM> which can be an injection molded plastic, for example, with the outer sleeve <NUM> insert molded therein. The inner sleeve member <NUM> is coupled drive coupling <NUM> that is configured for coupling to the rotating motor shaft <NUM> of motor drive unit <NUM>. More in particular, the rotatable cutting member <NUM> that is fabricated of a ceramic material with sharp cutting edges on opposing sides 152a and 152b of window <NUM> therein for cutting soft tissue. The motor drive <NUM> is operatively coupled to the ceramic cutter to rotate the cutting member at speeds ranging from <NUM>,<NUM> rpm to <NUM>,<NUM> rpm. In <FIG>, it can be seen that cutting member <NUM> also carries an RF electrode <NUM> in a surface opposing the window <NUM>. The cutting member <NUM> rotates and shears tissue in the toothed opening or window <NUM> in the outer sleeve <NUM> (<FIG>). A probe of the type shown in <FIG> is described in more detail in co-pending and commonly owned patent application <CIT> (Atty. Docket <NUM>-<NUM>) titled ARTHROSCOPIC DEVICES AND METHODS.

As can be seen in <FIG>, the probe <NUM> is shown in two orientations for detachable coupling to the handpiece <NUM>. More particularly, the hub <NUM> can be coupled to the handpiece <NUM> in an upward orientation indicated at UP and a downward orientation indicated at DN where the orientations are <NUM>° opposed from one another. It can be understood that the upward and downward orientations are necessary to orient the working end <NUM> either upward or downward relative to the handpiece <NUM> to allow the physician to interface the cutting member <NUM> with targeted tissue in all directions without having to manipulate the handpiece in <NUM>° to access tissue.

In <FIG>, it can be seen that the handle <NUM> is operatively coupled by electrical cable <NUM> to a controller <NUM> which controls the motor drive unit <NUM>. Actuator buttons 166a, 166b or 166c on the handle <NUM> can be used to select operating modes, such as various rotational modes for the ceramic cutting member <NUM>. In one variation, a joystick <NUM> can be moved forward and backward to adjust the rotational speed of the ceramic cutting member <NUM>. The rotational speed of the cutter can continuously adjustable or can be adjusted in increments up to <NUM>,<NUM> rpm. An LCD screen <NUM> is provided in the handpiece for displaying operating parameters, such as cutting member RPM, mode of operation, etc..

It can be understood from <FIG> that the system <NUM> and handpiece <NUM> is adapted for use with various disposable probes which can be designed for various different functions and procedures For example, <FIG> illustrates a different variation of a probe working end 200A that is similar to working end <NUM> of probe <NUM> of <FIG>, except the ceramic cutting member <NUM> extends distally from the outer sleeve <NUM> and the cutting member has burr edges <NUM> for cutting bone. The probe of <FIG> is described in more detail in co-pending and commonly owned patent application <CIT> (Atty. Docket <NUM>-<NUM>) titled ARTHROSCOPIC DEVICES AND METHODS. <FIG> illustrates a different variation of a probe working end 200B with a reciprocating electrode <NUM> in a type of probe described in more detail in co-pending and commonly owned patent application <CIT> (Atty. Docket <NUM>-<NUM>) titled ARTHROSCOPIC DEVICES AND METHODS. In another example, <FIG> illustrates another variation of a probe working end 200C that has an extendable-retractable hook electrode <NUM> in a probe type described in more detail in co-pending and commonly owned patent application <CIT> (Atty. Docket <NUM>-<NUM>) titled ARTHROSCOPIC DEVICES AND METHODS. In yet another example, <FIG> illustrates a variation of a working end 200D in a probe type having an openable-closable jaw structure <NUM> actuated by reciprocating member <NUM> for trimming meniscal tissue or other tissue as described in more detail in co-pending and commonly owned patent application <CIT> (Atty. Docket <NUM>-<NUM>) titled ARTHROSCOPIC DEVICES AND METHODS. All of the probes of <FIG> can have a hub similar to hub <NUM> of probe <NUM> of <FIG> for coupling to the same handpiece <NUM> of <FIG>, with some of the probes (see <FIG>) having a hub mechanism for converting rotational motion to linear motion.

<FIG> further shows that the system <NUM> also includes a negative pressure source <NUM> coupled to aspiration tubing <NUM> which communicates with a flow channel <NUM> in handpiece <NUM> and can cooperate with any of the probes <NUM>, 200A, 200B or 200C of <FIG>, <FIG>, <FIG> and <FIG>. In <FIG> it also can be seen that the system <NUM> includes an RF source <NUM> which can be connected to an electrode arrangement in any of the probes <NUM>, 200A, 200B or 200C of <FIG>, <FIG> and <FIG>. The controller <NUM> and microprocessor therein together with control algorithms are provided to operate and control all functionality, which includes controlling the motor drive <NUM> to move a motor-driven component of any probe working end <NUM>, 200A, 200B or 200C, as well as for controlling the RF source <NUM> and the negative pressure source <NUM> which can aspirate fluid and tissue debris to collection reservoir <NUM>.

As can be understood from the above description of the system <NUM> and handpiece <NUM>, the controller <NUM> and controller algorithms need to be configured to perform and automate many tasks to provide for system functionality. In a first aspect, controller algorithms are needed for device identification so that when any of the different probes types <NUM>, 200A, 200B, 200C or 200D of <FIG> and <FIG> are coupled to handpiece <NUM>, the controller <NUM> will recognize the probe type and then select algorithms for operating the motor drive <NUM>, RF source <NUM> and negative pressure source <NUM> as is needed for the particular probe. In a second aspect, the controller is configured with algorithms that identify whether the probe is coupled to the handpiece <NUM> in an upward or downward orientation relative to the handpiece, wherein each orientation requires a different subset of the operating algorithms. In another aspect, the controller has separate control algorithms for each probe type wherein some probes have a rotatable cutter while others have a reciprocating electrode or jaw structure. In another aspect, most if not all the probes <NUM>, 200A, 200B, 200C and 200D (<FIG>, <FIG>) require a default "stop" position in which the motor-driven component is stopped in a particular orientation within the working end. For example, a rotatable cutter <NUM> with an electrode <NUM> needs to have the electrode centered within an outer sleeve window <NUM> in a default position such as depicted in <FIG>. Some of these systems, algorithms and methods of use are described next.

Referring to <FIG> and <FIG>, it can be seen that handpiece <NUM> carries a first Hall effect sensor <NUM> in a distal region of the handpiece <NUM> adjacent the receiving passageway <NUM> that receives the hub <NUM> of probe <NUM>. <FIG> corresponds to the probe <NUM> and working end <NUM> in <FIG> being in the upward orientation indicated at UP. <FIG> corresponds to probe <NUM> and working end <NUM> in <FIG> being in the downward orientation indicated at DN. The handpiece <NUM> carries a second Hall effect sensor <NUM> adjacent the rotatable drive coupling <NUM> of the probe <NUM>. The probe <NUM> carries a plurality of magnets as will be described below that interact with the Hall effect sensors <NUM>, <NUM> to provide multiple control functions in cooperation with controller algorithms, including (i) identification of the type of probe coupled to the handpiece, (ii) the upward or downward orientation of the probe hub <NUM> relative to the handpiece <NUM>, and (iii) the rotational position and speed of rotating drive collar <NUM> from which a position of either rotating or reciprocating motor-driven components can be determined.

The sectional views of <FIG> show that hub <NUM> of probe <NUM> carries first and second magnets 250a and 250b in a surface portion thereof. The Hall sensor <NUM> in handpiece <NUM> is in axial alignment with either magnet 250a or 250b when the probe hub <NUM> is coupled to handpiece <NUM> in an upward orientation (<FIG> and <FIG>) or a downward orientation (<FIG> and <FIG>). In one aspect as outlined above, the combination of the magnets 250a and 250b and the Hall sensor <NUM> can be used to identify the probe type. For example, a product portfolio may have from <NUM> to <NUM> or more types of probes, such as depicted in <FIG> and <FIG>, and each such probe type can carry magnets 250a, 250b having a specific, different magnetic field strength. Then, the Hall sensor <NUM> and controller algorithms can be adapted to read the magnetic field strength of the particular magnet(s) in the probe which can be compared to a library of field strengths that correspond to particular probe types. Then, a Hall identification signal can be generated or otherwise provided to the controller <NUM> to select the controller algorithms for operating the identified probe, which can include parameters for operating the motor drive <NUM>, negative pressure source <NUM> and/or RF source <NUM> as may be required for the probe type. As can be seen in <FIG>, <FIG>, the probe hub <NUM> can be coupled to handpiece <NUM> in upward and downward orientations, in which the North (N) and South (S) poles of the magnets 250a, 250b are reversed relative to the probe axis <NUM>. Therefore, the Hall sensor <NUM> and associated algorithms look for magnetic field strength regardless of polarity to identify the probe type.

Referring now to <FIG>, <FIG> and <FIG>, the first and second magnets 250a and 250b with their different orientations of North (N) and South (S) poles relative to central longitudinal axis <NUM> of hub <NUM> are also used to identify the upward orientation UP or the downward orientation DN of hub <NUM> and working end <NUM>. In use, as described above, the physician may couple the probe <NUM> to the handpiece receiving passageway <NUM> with the working end <NUM> facing upward or downward based on his or her preference and the targeted tissue. It can be understood that controller algorithms adapted to stop rotation of the cutting member <NUM> in the window <NUM> of the outer sleeve <NUM> of working end <NUM> need to "learn" whether the working end is facing upward or downward, because the orientation or the rotating cutting member <NUM> relative to the handpiece and Hall sensor <NUM> would vary by <NUM>°. The Hall sensor <NUM> together with a controller algorithm can determine the orientation UP or the downward orientation DN by sensing whether the North (N) or South (S) pole of either magnet 250a or 250b is facing upwardly and is proximate the Hall sensor <NUM>.

In another aspect of the invention, in probe <NUM> (<FIG>) and other probes, the motor-driven component of a working end, such as rotating cutter <NUM> of working end <NUM> of <FIG> and <FIG>, needs to be stopped in a selected rotational position relative to a cut-out opening or window <NUM> in the outer sleeve <NUM>. Other probe types may have a reciprocating member, or a jaw structure as described above, which also needs a controller algorithm to stop movement of a moving component in a selected position, such as the axial-moving electrodes of <FIG> and the jaw structure of <FIG>. In all probes, the motor drive <NUM> couples to the rotating drive coupling <NUM>, thus sensing the rotational position of the drive coupling <NUM> can be used to determine the orientation of the motor-driven component in the working end. More in particular, referring to <FIG> and <FIG>, the drive coupling <NUM> carries third and fourth magnets 255a or 255b with the North (N) and South (S) poles of magnets 255a or 255b being reversed relative to the probe axis <NUM>. Thus, Hall sensor <NUM> can sense when each magnet rotates passes the Hall sensor and thereby determine the exact rotational position of the drive coupling <NUM> twice on each rotation thereof (once for each magnet 255a, 255b). Thereafter, a controller tachometer algorithm using a clock can determine and optionally display the RPM of the drive coupling <NUM> and, for example, the cutting member <NUM> of <FIG>.

In another aspect of the invention, the Hall sensor <NUM> and magnets 255a and 255b (<FIG> and <FIG>) are used in a set of controller algorithms to stop the rotation of a motor-driven component of a working end, for example, cutting member <NUM> of <FIG> and <FIG> in a pre-selected rotational position. In <FIG>, it can be seen that the inner sleeve member <NUM> and a "first side" of cutting member <NUM> and window <NUM> therein is stopped and positioned in the center of window <NUM> of outer sleeve <NUM>. The stationary position of cutting member <NUM> and window <NUM> in <FIG> may be used for irrigation or flushing of a working space to allow for maximum fluid outflow through the probe.

<FIG> depicts inner sleeve member <NUM> and a "second side" of cutting member <NUM> positioned about the centerline of window <NUM> in the outer sleeve <NUM>. The stationary or stopped position of cutting member <NUM> in <FIG> is needed for using the RF electrode <NUM> to ablate or coagulate tissue. It is important that the electrode <NUM> is maintained along the centerline of the outer sleeve window <NUM> since the outer sleeve <NUM> typically comprises return electrode <NUM>. The position of electrode <NUM> in <FIG> is termed herein a "centerline default position". If the cutting member <NUM> and electrode <NUM> were rotated so as to be close to an edge 262a or 262b of window <NUM> in outer sleeve <NUM>, RF current could arc between the electrodes <NUM> and <NUM> and potentially cause a short circuit disabling the probe. Therefore, a robust and reliable stop mechanism is required which is described next.

As can be understood from <FIG> and <FIG>, the controller <NUM> can always determine in real time the rotational position of drive coupling <NUM> and therefore the angular or rotational position of the ceramic cutting member <NUM> and electrode <NUM> can be determined. A controller algorithm can further calculate the rotational angle of the electrode <NUM> away from the centerline default position as the Hall sensor <NUM> can sense lessening of magnetic field strength as a magnet 255a or 255b in the drive coupling <NUM> rotates the electrode <NUM> away from the centerline default position. Each magnet has a specified, known strength and the algorithm can use a look-up table with that lists fields strengths corresponding to degrees of rotation away from the default position. Thus, if the Hall signal responsive to the rotated position of magnet 255a or 255b drops a specified amount from a known peak value in the centerline default position, it means the electrode <NUM> has moved away from the center of the window <NUM>. In one variation, if the electrode <NUM> moves a selected rotational angle away from the centerline position during RF energy delivery to the electrode, the algorithm turns off RF current instantly and alerts the physician by an aural and/or visual signal, such as an alert on the LCD screen <NUM> on handpiece <NUM> and/or on a screen on a controller console (not shown). The termination of RF current delivery thus prevents the potential of an electrical arc between electrode <NUM> and the outer sleeve electrode <NUM>.

It can be understood that during use, when the electrode <NUM> is in the position shown in <FIG>, the physician may be moving the energized electrode over tissue to ablate or coagulate tissue. During such use, the cutting member <NUM> and electrode <NUM> can engage or catch on tissue which inadvertently rotate the electrode <NUM> out of the default centerline position. Therefore, the system provides a controller algorithm, herein called an "active electrode monitoring" algorithm, wherein the controller continuously monitors position signals generated by Hall sensor <NUM> during RF energy delivery in both an ablation mode and a coagulation mode to determine if the electrode <NUM> and inner sleeve member <NUM> have been bumped off the centerline position. In a variation, the controller algorithms can be configured to then re-activate the motor drive <NUM> to move the inner sleeve member <NUM> and electrode <NUM> back to the default centerline position sleeve if electrode <NUM> had been bumped off the centerline position. In another variation, the controller algorithms can be configured to again automatically deliver RF current to RF electrode <NUM> when it is moved back to the to the default centerline position. Alternatively, the controller <NUM> can require the physician to manually re-start the delivery of RF current to the RF electrode <NUM> when it is moved back to the to the centerline position. In an aspect of the invention, the drive coupling <NUM> and thus magnets 255a and 255b are attached to inner sleeve member <NUM> and cutting member <NUM> in a pre-determined angular relationship relative to longitudinal axis <NUM> so that the Hall sensor generates signals responsive to magnets 255a, 255b is the same for all probes within a probe type to thus allow the controller algorithm to function properly.

Now turning to the stop mechanism or algorithms for stopping movement of a motor-driven component of working end <NUM>, <FIG> schematically illustrates the algorithm and steps of the stop mechanism. In one variation, referring to <FIG>, the stop mechanism corresponding to the invention uses (i) a dynamic braking method and algorithm to stop the rotation of the inner sleeve member <NUM> and cutting member <NUM> (<FIG>, <FIG>) in an initial position, and thereafter (ii) a secondary checking algorithm is used to check the initial stop position that was attained with the dynamic braking algorithm, and if necessary, the stop algorithm can re-activate the motor drive <NUM> to slightly reverse (or move forward) the rotation of drive coupling <NUM> and inner sleeve member <NUM> as needed to position the cutting member <NUM> and electrode <NUM> within at the centerline position or within <NUM>° to <NUM>° of the targeted centerline default position. Dynamic braking is described further below. <FIG> schematically illustrates various aspects of controller algorithms for controlling the rotational speed of the cutting member and for stopping the cutting member <NUM> in the default centerline position.

In <FIG>, it can be understood that the controller <NUM> is operating the probe <NUM> of <FIG> and <FIG> at a "set speed" which may be a PID controlled, continuous rotation mode in one direction or may be an oscillating mode where the motor drive <NUM> rotates the cutting member <NUM> in one direction and then reverses rotation as is known in the art. At higher rotational speeds such as <NUM>,<NUM> RPM to <NUM>,<NUM> RPM, it is not practical or feasible to acquire a signal from Hall sensor <NUM> that indicates the position of a magnet 255a or 255b in the drive coupling <NUM> to apply a stop algorithm. In <FIG>, when the physician stop cutting with probe <NUM> by releasing actuation of an actuator button or foot pedal, current to the motor drive <NUM> is turned off. Thereafter, the controller algorithm uses the Hall sensor <NUM> to monitor deceleration of rotation of the drive coupling <NUM> and inner sleeve member <NUM> until a slower RPM is reached. The deceleration period may be from <NUM> to <NUM> sec and typically is about <NUM>. When a suitable slower RPM is reached which is called a "search speed" herein (see <FIG>), the controller <NUM> re-activates the motor drive <NUM> to rotate the drive coupling at a low speed ranging from <NUM> RPM to <NUM>,<NUM> RPM and in one variation is between <NUM> RPM and <NUM> RPM. An initial "search delay" period ranging from <NUM> to <NUM> is provided to allow the PID controller to stabilize the RPM at the selected search speed. Thereafter, the controller algorithm monitors the Hall position signal of magnet strength and when the magnet parameter reaches a predetermined threshold, for example, when the rotational position of drive coupling <NUM> and electrode <NUM> correspond to the centerline default position of <FIG>, the control algorithm then applies dynamic braking to instantly stop rotation of the motor drive shaft <NUM>, drive coupling <NUM> and the motor-driven component of the probe. <FIG> further illustrates that the controller can check the magnet/drive coupling <NUM> position after the braking and stopping steps. If the Hall position signal indicates that the motor-driven component is out of the targeted default position, the motor drive <NUM> can be re-activated to move the motor-driven component and thereafter the brake can be applied again as described above.

Dynamic braking as shown schematically in <FIG> may typically stop the rotation of the drive coupling <NUM> with a variance of up to about <NUM>°- <NUM>° of the targeted stop position, but this can vary even further when different types of tissue are being cut and impeding rotation of the cutting member <NUM>, and also depending on whether the physician has completely disengaged the cutting member from the tissue interface when the motor drive is de-activated. Therefore, dynamic braking alone may not assure that the default or stop position is within a desired variance.

As background, the concept of dynamic braking is described in the following literature: https://www. com/support/abdrives/documentation/techpapers/RegenOverview01. Basically, a dynamic braking system provides a chopper transistor on the DC bus of the AC PWM drive that feeds a power resistor that transforms the regenerative electrical energy into heat energy. The heat energy is dissipated into the local environment. This process is generally called dynamic braking with the chopper transistor and related control and components called the chopper module and the power resistor called the dynamic brake resistor. The entire assembly of chopper module with 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 that circuit to be safely dissipated during the turn off of the chopper transistor.

The method is called dynamic braking because the amount of braking torque that can be applied is dynamically changing as the load decelerates. In other words, the braking energy is a function of the kinetic energy in the spinning mass and as it declines, so does the braking capacity. So the faster it is spinning or the more inertia it has, the harder you can apply the brakes to it, but as it slows, you run into the law of diminishing returns and at some point, there is no longer any braking power left.

In another aspect, a method has been developed to increase the accuracy of the stopping mechanism which is a component of the positioning algorithm described above. It has been found that each magnet in a single-use probe may vary slightly from its specified strength. As described above, the positioning algorithm uses the Hall effect sensor <NUM> to continuously monitor the field strength of magnets 255a and 255b as the drive coupling <NUM> rotates and the algorithm determines the rotational position of the magnets and drive coupling based on the field strength, with the field strength rising and falling as a magnet rotates past the Hall sensor. Thus, it is important for the algorithm to have a library of fields strengths that accurately correspond to degrees of rotation away from a peak Hall signal when a magnet is adjacent the sensor <NUM>. For this reason, an initial step of the positioning algorithm includes a "learning" step that allow the controller to learn the actual field strength of the magnets 255a and 255b which may vary from the specified strength. After a new single-use probe <NUM> (<FIG>) is coupled to the handpiece <NUM>, and after actuation of the motor drive <NUM>, the positioning algorithm will rotate the drive coupling at least <NUM>° and more often at least <NUM>° while the Hall sensor <NUM> quantifies the field strength of the particular probe's magnets 255a and 255b. The positioning algorithm then stores the maximum and minimum Hall signals (corresponding to North and South poles) and calibrates the library of field strengths that correspond to various degrees of rotation away from a Hall min-max signal position when a magnet is adjacent the Hall sensor.

In general, a method of use relating to the learning algorithm comprises providing a handpiece with a motor drive, a controller, and a probe with a proximal hub configured for detachable coupling to the handpiece, wherein the motor drive is configured to couple to a rotating drive coupling in the hub and wherein the drive coupling carries first and second magnets with North and South poles positioned differently relative to said axis, and coupling the hub to the handpiece, activating the motor drive to thereby rotate the drive coupling and magnets at least <NUM>°, using a handpiece sensor to sense the strength of each magnet, and using the sensed strength of the magnets for calibration in a positioning algorithm that is responsive to the sensor sensing the varying strength of the magnets in the rotating drive coupling to thereby increase accuracy in calculating the rotational position of the drive coupling <NUM>.

Another aspect relates to an enhanced method of use using a probe working end with an electrode, such as the working end <NUM> of <FIG> and <FIG>. As described above, a positioning algorithm is used to stop rotation of the electrode <NUM> in the default centerline position of <FIG>. An additional "slight oscillation" algorithm is used to activate the motor drive <NUM> contemporaneous with RF current to the electrode <NUM>, particularly an RF cutting waveform for tissues ablation. The slight oscillation thus provides for a form of oscillating RF ablation. The slight oscillation algorithm rotates the electrode <NUM> in one direction to a predetermined degree of rotation, which the controller algorithms determine from the Hall position signals. Then, the algorithm reverses direction of the motor drive to rotate in the opposite direction until Hall position signals indicate that the predetermined degree of rotation was achieved in the opposite direction away from the electrode's default centerline position. The predetermined degree of angular motion can be any suitable rotation that is suitable for dimensions of the outer sleeve window, and in one variation is from <NUM>° to <NUM>° in each direction away from the centerline default position. More often, the predetermined degree of angular motion is from <NUM>° to <NUM>° 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 <NUM> RPM to <NUM>,<NUM> RPM, and more often from <NUM> RPM to <NUM>,<NUM> RPM. Stated another way, the frequency of oscillation can be from <NUM> to <NUM>,<NUM> and typically between <NUM> and <NUM>.

While the above description of the slight oscillation algorithm is provided with reference to electrode <NUM> on a rotating cutting member <NUM> of <FIG>, it should be appreciated that a reciprocating electrode <NUM> as shown in the working end 200C of <FIG> end could also be actuated with slight oscillation. In other words, the hook shape electrode <NUM> of <FIG> could be provided with a frequency of oscillation ranging from <NUM> to <NUM>,<NUM> and typically between <NUM> and <NUM>.

<FIG> are longitudinal sectional views of a probe hub <NUM>' that corresponds to the working end 200B of <FIG> which has a reciprocating electrode <NUM>. In <FIG>, the handpiece <NUM> and Hall affect sensors <NUM> and <NUM> are of course the same as described above as there is no change in the handpiece <NUM> for different types of probes. The probe hub <NUM>' of <FIG> is very similar to the hub <NUM> of <FIG> with the first and second identification/orientation magnets 250a and 250b being the same. The third and fourth rotation al position magnets 255a and 255b also are the same and are carried by drive coupling <NUM>'. The probe hub <NUM>' of <FIG> only differs in that the drive coupling <NUM> rotates with a cam mechanism operatively coupled to inner sleeve member <NUM>' to convert rotational motion to linear motion to reciprocate the electrode <NUM> in working end 200B of <FIG>. A similar hub for converting rotational motion to linear motion is provided for the working ends 200C and 200D of <FIG>, respectively, which each have a reciprocating component (<NUM>, <NUM>) in its working end.

Now turning to <FIG>, <FIG> and <FIG>, another variation of an arthroscopic shaver or resection probe <NUM> is shown which somewhat similar to that of <FIG>, <FIG> and <FIG> which comprises a tubular cutter having a proximal hub <NUM> coupled to an elongated shaft assembly <NUM> that extends about central longitudinal axis <NUM>, in accordance with the invention. The shaft assembly comprises an outer sleeve assembly <NUM> and a co-axial or concentric inner sleeve member <NUM> that extends to a distal or a working end <NUM>. The hub <NUM> again is adapted for coupling to a handpiece and motor drive controlled by a controller 420A. The controller 420A further controls the RF source 420B and negative pressure source 420C as described previously. The controller 420A includes algorithms having the features described in previous embodiments for rotating the inner sleeve member <NUM> as well as stopping the inner sleeve member <NUM> in a selected rotational position, such as a window-closed or window-open position. The distal or working end <NUM> again has an outer sleeve resecting window <NUM> in the outer sleeve assembly <NUM> that cooperates with an inner sleeve member resecting window <NUM> (<FIG>) in the inner sleeve member <NUM> for engaging and resecting tissue.

The variation or probe <NUM> in <FIG>, <FIG> and <FIG> differs from previous embodiments in that the inner sleeve member <NUM> of the distal or working end <NUM> (<FIG>, <FIG>) that consists of a combination of a first longitudinal member comprising a dielectric structure or body <NUM>, typically formed as an insert, coupled to a second longitudinal member comprising a conductive structure or portion <NUM>, typically a generally tubular structure having an axial channel to receive the dielectric insert. The dielectric member <NUM> can be a ceramic or glass material and the longitudinal conductive structure <NUM> typically is stainless steel or other conductive metal. When assembled, the dielectric member <NUM> and longitudinal conductive structure <NUM> have longitudinal surfaces that contact one another along an interface <NUM> which is important for reasons described in more detail below.

As can be seen in <FIG>, which shows components of the inner sleeve member <NUM> separated, the longitudinal dielectric member <NUM> carries an active electrode <NUM> which may be also may be referred to as a "first polarity" electrode herein. For convenience, the side of the inner sleeve member <NUM> that carries the electrode <NUM> is called the electrode side ES and the opposing side which carries inner window <NUM> is called the window side WS. Referring to <FIG>, the inner sleeve resecting window <NUM> has circumferentially spaced apart first and second cutting edges 448a and 448b that are sharp for mechanically resecting tissue as such cutting edges 448a, 448b shear tissue when rotating or rotationally oscillating adjacent the cutting edges 450a and 450b of the outer sleeve window <NUM>. In one variation shown in <FIG>, the first and second cutting edges 448a and 448b are asymmetric with cutting teeth on one side and without such teeth on the opposing side. It should be appreciated that any types of symmetric or asymmetric edges are possible, such as serrated, linear, configured with teeth, etc..

Of particular interest, the longitudinal conductive metal structure <NUM> comprises a first return electrode 455A (which also may be termed a "second polarity" electrode herein) which cooperates with the first polarity or active electrode <NUM> to deliver energy to tissue. As will be described below, a distal portion the outer sleeve <NUM> comprises a second return electrode 455B. The active electrode <NUM> and return electrodes 455A and 455B are operatively coupled to RF source 420B and controller 420A. The outer sleeve assembly <NUM> has a conductive metal outer tubular member <NUM> with axial bore <NUM> therein that extends proximally to the hub <NUM> and distally to the distal end portion or housing <NUM> that carries the outer sleeve window <NUM>. The inner sleeve member <NUM> has a co-axial conductive metal inner tubular member <NUM> that extends proximally to the hub <NUM> and extends distally to couple to the assembly of the longitudinal dielectric member <NUM> and the longitudinal metal structure <NUM>. The co-axial metal inner tubular member <NUM> rotates in the axial bore <NUM> of the outer tubular member <NUM>.

As can be seen best in <FIG> and <FIG>, the longitudinal metal structure <NUM> has dual functions in that the carries the inner cutting window <NUM> with circumferentially spaced-apart first and second cutting edges 448a and 448b and also functions as return electrode 455A when in a window-closed position of <FIG>, as will be described further below.

Now referring to <FIG>, the inner sleeve member <NUM> again is shown separated from the outer sleeve assembly <NUM> and is rotated <NUM>° so that the electrode side ES faces downward and the window side WS is in an upward position. It can be seen that the longitudinal metal structure <NUM> carries the inner resecting window <NUM>. Further, the longitudinal metal structure <NUM> extends distally around the tip portion <NUM> of the inner sleeve member <NUM> to thus provide substantial hoop strength as the tip portion <NUM> distally surrounds the longitudinal dielectric member <NUM> on opposing sides of the distal end <NUM> of the dielectric member <NUM>. As can be seen in <FIG>, the proximal end <NUM> of the assembly of the longitudinal dielectric member <NUM> and the longitudinal metal structure <NUM> is dimensioned for insertion into the axial channel or axial bore <NUM> of the thin wall tubular sleeve <NUM> to complete the structural components of the inner sleeve member <NUM>. Thus, it can be seen how the tubular sleeve <NUM> with axial channel or axial bore 466therein slides over and engages with the longitudinal dielectric member <NUM> and longitudinal metal structure <NUM> to provide a strong connection around the proximal end <NUM> of the components. As can best be seen in <FIG>, the lateral sides 470a and 470b of the longitudinal dielectric member <NUM> are configured to slide into receiving recesses or grooves 472a and 472b on either side of the open axial channel <NUM> in the longitudinal metal structure <NUM> to thereby lock the two components <NUM> and <NUM> together.

<FIG> shows the exploded view of the components of <FIG> rotated <NUM>° degrees to again show the lateral sides 470a, 470b of the dielectric member <NUM> configured for insertion into the receiving grooves 472a, 472b on either side of the axial channel <NUM> in the longitudinal metal structure <NUM>.

Now turning to <FIG> and <FIG>, the electrical connections to the active electrode <NUM> and return electrodes 455A, 455B can be described. In the exploded view of <FIG>, it can be seen that an elongated electrical lead <NUM> is adapted to extend longitudinally over the inner tubular member <NUM> (<FIG>) to a pad portion <NUM> that is bendable and adapted to be inserted into a pad recess <NUM> in the longitudinal dielectric member <NUM>. The electrical lead <NUM> is covered with an insulator (not shown) except for the pad portion <NUM>. As can be easily understood, the active electrode <NUM> comprises a metal such as stainless steel, tungsten or any other suitable conductive metal with first and second legs 478a and 478b that are adapted for insertion through receiving channels 482a and 482b in the dielectric member <NUM> which extend into the pad recess <NUM>. Thus, it can understood that the electrode <NUM> is cantilevered over a grooved portion <NUM> of the dielectric member <NUM> distally from the dual receiving channels 482a and 482b in the dielectric member <NUM>. The pad <NUM> of the electrical lead <NUM> then is placed in the contact with the legs 478a and 478b of the electrode <NUM> and soldered or otherwise electrically coupled in the recess <NUM>. Finally, a potting material (not shown) is used to cover and fill in over the electrical pad <NUM> and the recess <NUM>. Further, referring to <FIG>, it can be seen that tubular member <NUM> has a flattened surface <NUM> for accommodating the electrical lead <NUM> as the tubular member <NUM> and axial channel or axial bore <NUM> therein slide over the proximal end <NUM> of the dielectric member <NUM> and metal portion <NUM>. The flattened surface <NUM> of the tubular member <NUM> as seen in <FIG> allows an insulator layer <NUM> (such as a heat shrink material) shown in phantom view to cover the entirety of the tubular member <NUM>, the insulated electrical lead <NUM>, and the proximal and medial portions <NUM>, <NUM> of the dielectric member <NUM> and the longitudinal metal structure <NUM>. This describes the electrical lead <NUM> extending to the active electrode <NUM> carried within the dielectric member <NUM>. The proximal end (not shown) of the electrical lead <NUM> extends into the hub <NUM> (<FIG>) and thereafter connects to electrical contacts in a motor-drive handpiece which allows for rotation of the inner sleeve member <NUM> and for coupling electrical energy to the electrical lead <NUM>, as described in earlier embodiments.

As described above, the longitudinal metal structure <NUM> of the inner sleeve member <NUM> (<FIG>, <FIG>) comprises the first return electrode 455A. However, the inner sleeve member <NUM> does not carry an electrical lead to the longitudinal metal structure <NUM>. Rather, the outer sleeve assembly <NUM> of <FIG>, <FIG> and <FIG> includes an elongate metal outer tubular member <NUM> that comprises an electrical conductor and is adapted to carry current from the hub <NUM> to the distal end or housing portion <NUM> of the outer sleeve assembly <NUM>. Since the longitudinal metal structure <NUM> of the inner sleeve member <NUM> rotates with a close fit within the axial bore <NUM> of the outer tubular member <NUM>, the longitudinal metal structure <NUM> becomes a return electrode 455A due to its contact with the outer tubular member <NUM>. Thus, referring to <FIG>, the longitudinal metal conductive structure <NUM> and the distal end housing <NUM> of the outer tubular member <NUM> comprise first and second return electrodes 455A and 455B, respectively.

In another aspect of the invention, referring to <FIG> and <FIG>, the active electrode <NUM> is dome-shaped with a surface <NUM> that has a radius or curvature that is a segment of a cylindrical shape so that the outer surface <NUM> of the dome of the electrode <NUM> when viewed in a transverse sectional view (<FIG>) is substantially aligned with the outer cylindrical surface <NUM> of the dielectric member <NUM> and outer surface <NUM> of the longitudinal metal structure <NUM>. The dome-shaped surface <NUM> of the electrode <NUM> is advantageous for contacting tissue since it projects outward as opposed to a flat-surface electrode. Further, the thicker, dome-shaped central surface of active electrode <NUM> results in far slower degradation and disintegration of the electrode <NUM> during prolonged use. The durability of active electrode <NUM> is important for arthroscopic procedures in which the electrosurgical components of the invention may be used for many minutes. Referring to <FIG>, the radius R1 of the outer surface <NUM> of the active electrode <NUM> is approximately equal to the radius R2 of the outer surface <NUM> of dielectric member <NUM>. In one variation, the radius R1 of outer surface <NUM> of electrode <NUM> is smaller than radius R2 of outer surface <NUM> of the dielectric member <NUM> by <NUM>" (<NUM>) or less. Similarly, the radius R2 of the outer surface <NUM> of the dielectric member <NUM> is approximately equal to radius R3 of the outer surface <NUM> of the longitudinal metal structure <NUM>. In one variation, the radius R2 of dielectric member <NUM> is smaller than radius R3 of metal structure <NUM> by <NUM>" (<NUM>) or less. These dimensions are important for providing the inner sleeve member <NUM> with a rotating close fit within axial bore <NUM> of the outer tubular member <NUM> and distal housing <NUM>.

Referring to <FIG> and <FIG>, in one aspect of the invention, the longitudinal dielectric member <NUM> is formed as a curved, annular dielectric portion. The longitudinal metal structure <NUM> can also be formed as a C-shaped annular portion or segment to form a wall <NUM> (with metal wall portion 501a and dielectric wall portion 501b) around an interior channel <NUM> therein that communicates within axial channel or axial bore <NUM> in the inner tubular member <NUM> and a negative pressure source 420C for aspirating tissue chips and fluid from a working space as is known in the art. The annular dielectric portion <NUM> can be assembled with the C-shaped annular metal portion to form a generally tubular or cylindrical distal housing.

As will be further explained below, the dimensions and orientations of several elements of the active electrode <NUM>, the dielectric member <NUM> and the conductive structure <NUM> in relation to the outer sleeve window <NUM> are important. In a variation shown in <FIG>, the active electrode <NUM> has an outer surface <NUM> extending over a radial angle RA1 of at least <NUM>°. Often, the outer surface <NUM> of electrode <NUM> extends over a radial angle RA1 of at least <NUM>°. In this variation, the lateral electrode edges 504a and 504b are spaced apart from the closest aspect of metal structure <NUM> at interface <NUM> by a radial angle RA2 of at least <NUM>° and often at least <NUM>°. The minimum dimensional angle RA2 between the electrode edges 504a, 504b and interface <NUM> is needed to provide for optimal plasma ignition when using the probe in an plasma ablation mode.

<FIG> and <FIG> also show a minimum radial angle dimension RA3 of side wall portions 505a and 505b of the conductive structure <NUM> that extend on either side of inner window <NUM>. This radial angle RA3 indicates the minimum height of such wall portions 505a, 505b from the recesses <NUM> between teeth <NUM> (<FIG> and <FIG>) to the interface <NUM> which provides the assembly of the dielectric member <NUM> and metal structure <NUM> with needed strength during use. As can be seen in <FIG>, the metal side wall portions 505a, 550b form the respective inner window cutting edges 448a, 448b and the outer surface <NUM> of side walls 505a and 505b extend over a radial angle at least <NUM>° and often at least <NUM>°.

Referring now to <FIG>, in another aspect of the invention, important characteristics of the active electrode <NUM>, dielectric member <NUM> and longitudinal metal structure <NUM> can be further described by certain dimensions other that a radial angle. In one aspect, the active electrode <NUM> has an outer surface <NUM> extending circumferentially dimension D1 at least <NUM>" (<NUM>). The metal side wall portions 505a and 505b that form the edges of inner window <NUM> have an outer surface <NUM> extending circumferentially a dimension D2 of at least <NUM>' (<NUM>). Further, the lateral edges 504a and 504b of electrode <NUM> are spaced apart dimension D3 from the closest surface of metal structure <NUM> by at least <NUM>" (<NUM>). In <FIG>, it can be seen that dimension D3 equals the distance over the exposed surface <NUM> of dielectric structure <NUM>. In <FIG> and <FIG>, the active electrode <NUM> is shown with an outer surface <NUM> that is symmetric circumferentially relative to dielectric member <NUM> and inner window <NUM>, but it should be appreciated that electrode <NUM> can be asymmetric circumferentially relative to the dielectric member <NUM> and/or inner window <NUM>.

Referring now to <FIG>, a sectional, exploded view of dielectric member <NUM> and metal structure <NUM> is shown with the section taken proximal to window <NUM> (see <FIG>). As can seen in <FIG>, the wall <NUM> has an annular metal portion 501a and an annular dielectric portion 501b extending radially around axis <NUM> and interior channel <NUM>. The metal wall portion 501a typically will extend radially around interior channel <NUM> in a radial angle RA4 of at least <NUM>° or at least <NUM>°. When describing the metal wall portion 501a herein that extends in radial angle RA4 as in <FIG>, it is meant to refer to the metal wall portion 501a which is proximal to window <NUM>. The dimension of radial angle RA4 provides the required hoop strength to the metal portion <NUM> and thus the distal end of the inner sleeve member. In this variation, referring to <FIG>, the wall 501b of dielectric member <NUM> extends radially around interior channel <NUM> proximal to window <NUM> in a radial angle RA5 of at least <NUM>° or at least <NUM>°.

Now turning to <FIG>, another important aspect of the invention can be described. As can be seen in <FIG>, the inner sleeve member <NUM> has been stopped from rotation in a selected rotational position wherein the active electrode <NUM> carried by dielectric member <NUM> is positioned centrally in resecting window <NUM> of the outer sleeve assembly <NUM>. In this variation, it should be appreciated that the outer sleeve window <NUM> is shown with sharp metal cutting edges without teeth or serrations, but it should be appreciated that the outer sleeve window <NUM> can have any form of sharp teeth, serrations or the like.

In <FIG>, it can also be seen that the longitudinal metal structure <NUM> of the inner sleeve member <NUM> is exposed in the outer sleeve window <NUM> when the outer sleeve assembly <NUM> has been stopped in the rotational position where electrode <NUM> is positioned centrally in the resecting window <NUM>. As described above, the longitudinal metal structure <NUM> of the inner sleeve member <NUM> comprises a first return electrode 455A and the distal portion of housing <NUM> of outer sleeve assembly <NUM> comprises a second return electrode 455B. <FIG> shows RF current paths CP that indicate the shortest path for RF current between the active electrode <NUM> and a return electrode when operating in conductive saline environment. As can be seen in <FIG>, the shortest RF current paths CP are from the active electrode <NUM> to the longitudinal metal structure <NUM> (i.e., first return electrode 455A) along interface <NUM> of the dielectric member <NUM> and metal structure <NUM>. In other words, the shortest RF current path is not from the active electrode <NUM> to the cutting edges 450a and 450b of the outer window <NUM> in distal housing <NUM> which comprise the second return electrode 455B. In one aspect of the invention, the location of interface <NUM> between dielectric member <NUM> and metal structure <NUM> in the selected stopped position (or window closed position) is critical to prevent a short current path CP to the cutting edges 450a and 450b of outer window <NUM> (i.e., second return electrode 455A). If substantial RF current paths were directly from electrode <NUM> to cutting edges 450a and 450b, the RF plasma at the cutting edges would rapidly degrade and dull such sharp edges 450a, 450b. In turn, such dull cutting edges 450a, 450b of the outer sleeve window <NUM> would diminish the resection rate resulting from rotating or oscillating the inner sleeve member <NUM> and inner window <NUM> in the outer sleeve window <NUM>.

In general, a surgical a probe for resecting tissue corresponding to the invention (<FIG>) comprises an elongated shaft extending about a longitudinal axis <NUM> comprising co-axial outer and inner sleeve assemblies <NUM>, <NUM> having respective outer and inner resecting windows <NUM> and <NUM> in distal ends thereof, wherein the inner sleeve member has (i) a longitudinal dielectric wall member that carries a first polarity or active electrode <NUM>, and (ii) a conductive metal wall structure <NUM> with side wall portions 505a and 505b extending around an inner resecting window <NUM> that comprise a first return electrode 455A, wherein the active electrode <NUM> is spaced apart from the side wall portions 505a, 505b by at least <NUM>" (<NUM>) as described above.

In general, referring to <FIG>, a tissue resecting probe corresponding to the invention comprises an elongated shaft <NUM> extending about a longitudinal axis <NUM> and further comprises co-axial outer and inner sleeve assemblies <NUM> and <NUM> having respective outer and inner resecting windows <NUM> and <NUM> in distal ends thereof, wherein inner sleeve member <NUM> carries a first polarity or active electrode <NUM> therein, and the structure around the inner window <NUM> comprises a second polarity or return electrode 455A. In this variation, the structure at least partially surrounding the outer window <NUM> comprises second polarity or return electrode.

In another aspect of the invention, again referring <FIG>, the surgical resecting probe comprises a windowed inner sleeve member <NUM> rotatable within a windowed outer sleeve assembly <NUM> wherein a controller 420A and motor drive are adapted to rotate the inner sleeve member through window-open and window-closed positions and wherein the controller 420A is adapted to stop motor-driven rotation of the inner sleeve member in a selected position wherein the active electrode <NUM> is spaced apart from cutting edges 450a and 450b (i.e., the second return electrode 455B) of outer sleeve window <NUM> and wherein the first return electrode 455A is disposed intermediate the active electrode <NUM> and the cutting edges 450a and 450b of the outer sleeve window <NUM> (i.e., the second return electrode 455B). This aspect of the invention can be also be described by the dimensions of the surfaces of inner sleeve components relative to the outer window <NUM> of outer sleeve <NUM>. As can be seen in <FIG>, the radial angle RA1 of the electrode <NUM> and the radial angles RA2 of the dielectric member <NUM> on both sides of the electrode can be combined to define a first radial angle, and the outer window <NUM> in the outer sleeve <NUM> defines a second radial angle indicated at RA6. In this aspect, the second radial angle RA6 is greater than combined radials angles defined by the surfaces of the electrode <NUM> and dielectric member <NUM> of the inner sleeve <NUM> which can be rotated and then stopped in the outer window <NUM> of outer sleeve <NUM>. Typically, the radial angle RA6 of the outer window <NUM> is at least <NUM>° or at least <NUM>°.

In another aspect of the invention, referring to <FIG>, <FIG>and <FIG>, the resecting probe <NUM> (<FIG>) comprises a windowed inner sleeve member <NUM> rotatable within a windowed outer sleeve assembly <NUM> wherein a controller 420A (<FIG>) and motor drive are adapted to rotate the inner sleeve member <NUM> through window-open and window-closed positions, wherein a distal portion of the inner sleeve member <NUM> comprises a cylindrical wall <NUM> defining an outer surface and an inner surface <NUM> around interior channel <NUM> therein (see <FIG>, <FIG>). In <FIG>, it can be seen that interior channel <NUM> is surrounded by a first wall portion 501a with inner surface 512a of metal structure <NUM> and a second wall portion 501b with inner surface 512b of the longitudinal dielectric member <NUM> and wherein each of the first and second wall portions 501a and 501b comprise the full thickness of the cylindrical wall <NUM> and provide the structural strength of the wall. This aspect of the invention allows for that maximum diameter of the interior channel <NUM> relative to the outer diameter of the assembly <NUM> wherein such a larger interior channel facilitates fluid flows and tissue chip extraction. The above-described means of assembling the wall <NUM> is this preferred over having a wall that is layered, for example with a metal inner sleeve and dielectric outer sleeve or partial sleeve to carry the electrode. As can be seen in <FIG>, the radii R and R' of the inner surfaces 512a and 512b, respectively, are approximately the same dimension. Again, it should be appreciated that the term "wall" <NUM> as used herein describes the metal wall structure proximal to window <NUM> or dielectric structure opposing the window.

In <FIG>, it can be seen that the dielectric member <NUM> has a port <NUM> therein that lies under a v-notch <NUM> in the electrode <NUM>. The port <NUM> is adapted for aspiration of fluid therethrough during RF energy delivery in an ablation mode which can reduce bubbles from the vicinity of the active electrode <NUM> as plasma is generated. Further, <FIG> and <FIG> show ports <NUM> in the distal end housing <NUM> of outer sleeve <NUM> which are adapted to provide fluid flow through the shaft assembly in a window-closed position as shown in <FIG> and <FIG> to maintain a constant fluid outflow as opposed to a fluctuating outflow as would be the case otherwise with the inner sleeve member <NUM> rotating at high RPM through window-open and window-closed positions.

Now turning to <FIG>, another variation of a probe working end <NUM> is shown, and more particularly the distal end of the inner sleeve member <NUM>' is shown in an exploded view and is similar to the embodiment of <FIG>. The variation of <FIG> again includes a longitudinal dielectric body <NUM>' and a longitudinal conductive metal body <NUM>'. This variation differs the previous embodiment shown in <FIG> in that the structure provided for securely coupling the components <NUM>' and <NUM>' together differs. As can be seen in <FIG> and <FIG>, the dielectric component <NUM>' has lateral elements 540a and 540b extending in a part-cylindrical form that are adapted to slide into and engage the inner surfaces <NUM> of walls <NUM> of the metal longitudinal metal body portion <NUM>'. As can be seen best in <FIG>, the lateral elements 540a and 540b of the dielectric member <NUM>' have an outer surface <NUM> with a radius RR that matches the inner surface <NUM> and radius RR of the metal portion <NUM>'. Thus, it can be understood that by axially sliding and inserting the dielectric member <NUM>' can into the longitudinal opening or channel <NUM> in longitudinal metal portion <NUM>', a secure and durable connection can be provided between the dielectric and metal components <NUM>' and <NUM>'. In <FIG>, the radial angle RA1 of the surface of the electrode <NUM>, the radial angle RA2 of a portion of the dielectric member <NUM>', and the radial angle RA3 of wall portion of the metal body <NUM>' and the can be the same as described previously.

In <FIG>, another variation of a working end <NUM> of an inner sleeve member <NUM> is provided in an exploded view to illustrate the structural components that are adapted to securely connect the longitudinal dielectric member <NUM> to the longitudinal metal body <NUM>. In this variation, the lateral edges 624a and 624b of the dielectric member <NUM> do not interlock with the lateral edges 628a and 628b of the metal body <NUM> or overlap as in the previous variations. As can be seen in <FIG> and <FIG>, the interfaces of the lateral edges of the components <NUM>, <NUM> simply abut one another and are securely fixed to one another by a retaining collar <NUM> that is adapted to fit into an annular notch or recess <NUM> in both the dielectric member <NUM> the metal body <NUM> to securely hold the components together. As can be understood, the metal retaining collar <NUM> can have a discontinuity or gap <NUM> in its circumference to allow the collar to be tensioned and slipped over the components <NUM> and <NUM> into the recess <NUM>. Thereafter, the gap <NUM> in the collar <NUM> can be welded to thus permanently couple the dielectric and metal components <NUM> and <NUM>.

In the variation shown in <FIG>, it can be seen that an active electrode <NUM> with legs 652a and 652b is similar to the version described previously in <FIG>. In <FIG>, it can be seen that the legs 652a and 652b extend into receiving channels 654a and 654b in the dielectric member <NUM>. The electrical lead <NUM> in <FIG> again has a pad element <NUM> that is received by a recess <NUM> in the dielectric member <NUM> to contact electrical leads <NUM> therein. In this variation, the electrical leads <NUM> in the recess <NUM> are bare to make electrical contact with the pad element <NUM> but are coated with an insulator <NUM> in the location where such leads extend through the dielectric member <NUM> and into contact with the legs 652a and 652b of the electrode <NUM>. In all other respects, the assembly of components in <FIG> functions in the same manner as described previously.

Now turning to <FIG>, another variation of probe <NUM> is shown with hub <NUM> and shaft <NUM> (see <FIG>) extending about longitudinal axis <NUM> to a working end <NUM> shown in <FIG> shows a distal portion of the outer sleeve assembly <NUM> and axial bore <NUM> therein together with inner sleeve member <NUM>. <FIG> shows the inner sleeve member <NUM> from a different angle to better illustrate the electrical lead <NUM> carried by the inner sleeve. Now turning to <FIG>, which is an exploded view of the inner sleeve member <NUM>, it can be seen that the longitudinal dielectric member <NUM> is again secured to the longitudinal metal body <NUM> and coupled to tubular member <NUM> with a retaining collar <NUM>. Such a retaining collar <NUM> used to fix together the dielectric member <NUM> and the metal body <NUM> can be similar to that described in the embodiment of <FIG>.

Referring to <FIG>, this variation differs from previous embodiments in that the electrical lead <NUM> extends through a recess <NUM> in the dielectric member <NUM> and couples to a leg <NUM> of the active electrode <NUM>. The electrical lead <NUM> is not carried on an exterior surface of tubular member <NUM>. Instead, the electrical lead <NUM> extends to the active electrode <NUM> through the interior bore <NUM> of the tubular member. As can be seen in <FIG>, the electrical lead <NUM> extends in the proximal direction from the electrode <NUM> and is flexed at bend <NUM> to enter the interior bore <NUM> of the inner tubular member <NUM> and in this variation extends through a hypotube <NUM> which is coupled to the wall of the tubular member <NUM>. It can be seen that a slot <NUM> is provided in the wall of and tubular member <NUM> which allows for welding the hypotube <NUM> to the interior surface of bore <NUM> in the tubular member <NUM>. At least one similar slot (not shown) can be provided along the length of the tubular member <NUM> to secure the hypotube <NUM> in place. It has been found that is important to carry the electrical lead <NUM> within the interior bore <NUM> of the tubular member <NUM> to protect it from potential damage. In the previous embodiments, for example the version of <FIG>, the electrical lead <NUM> extended in a flat surface <NUM> along the outer surface of the inner tubular member <NUM> and was then covered with insulator layer <NUM>. In the previous embodiment of <FIG>, since the shaft <NUM> of the probe <NUM> (<FIG>) could be torqued and bent significantly during a procedure, high-speed rotation of the inner sleeve member <NUM> had the potential of abrading and degrading the insulator sleeve <NUM> overlying the electrical lead <NUM> which could cause an electrical short. Therefore, one aspect as shown in <FIG> includes carrying the electrical lead <NUM> in the interior bore <NUM> of the metal tubular member <NUM> to ensure that bending or torque on the shaft <NUM> while operating the inner sleeve member <NUM> at high RPM cannot damage the electrical lead <NUM>. <FIG> and <FIG> also show an annular bushing <NUM> that is adapted to cover the recess <NUM> that is filled with potting material as described previously. Referring again to <FIG>, a heat shrink insulator sleeve <NUM> covering the tubular member <NUM> and the at least a portion of the bushing <NUM>. Thus, in high speed rotation, the insulator sleeve <NUM> and bushing <NUM> are the bearing surfaces of the inner sleeve member <NUM> as it rotates in the outer sleeve <NUM>.

It can be appreciated from <FIG> that the inner tubular member <NUM> and the hypotube <NUM> comprise a return electrode <NUM> with conductive saline flowing through the interior channel <NUM> of the tubular member <NUM>. Thus, obviously the electrical lead <NUM> carries its own substantial insulation layer on it surface. In one variation, the electrical lead <NUM> is a copper wire, platinum wire or the like, instead of a stainless-steel wire since such a stainless-steel wire would be resistively heated. The electrical lead <NUM> is of a material that will not be resistively heated as this would heat saline outflows traveling through the channel <NUM> which would then elevate the temperature of the handpiece which is undesirable.

Now turning to <FIG>, a perspective view and a cut-away view of the hub <NUM> are shown. <FIG> is an enlarged cut-away view of an interior portion of the hub <NUM>. As can be seen in <FIG> and <FIG>, the hypotube <NUM> carries the electrical lead <NUM> that extends through the inner tubular member <NUM>. As can be seen in <FIG>, the tubular member <NUM> extends through the hub <NUM> and the hypotube <NUM> has a proximal end <NUM> in the interior of the hub. The proximal end portion <NUM> of the electrical lead <NUM> is curved outwardly through a slot <NUM> in the tubular member <NUM> and then extends in an interface <NUM> between two polymer collars <NUM> and <NUM> that together provide a seal over and around the insulation layer on the electrical lead <NUM>. Thereafter, a heat shrink material <NUM> such as FEP can disposed over the collars <NUM> and <NUM> (<FIG>). In <FIG> and <FIG>, it can be seen that a polymeric coupling sleeve <NUM> is fixed to the proximal end portion <NUM> of the tubular member that extends proximally to the drive coupler <NUM> which is adapted for coupling to the motor drive of the handpiece (not shown). <FIG> and <FIG> further show conductive metal contact ring <NUM> is disposed over the insulative coupling sleeve <NUM>. As can be seen in <FIG>, on the proximal side of the contact ring <NUM>, another polymeric collar <NUM> is shown that again is covered with an FEP or other heat shrink material. Still referring to <FIG>, the proximal-most end <NUM> of electrical lead <NUM> with its insulator layer removed is in contact with and electrically coupled to the rotating contact ring <NUM>. In turn, the contact ring <NUM> interfaces with spring-loaded ball contacts 780a and 780b in the handpiece (not shown) to carry RF current to from RF source 720B to the active electrode <NUM> (<FIG>). Spring-loaded ball contacts 782a and 782b in the hub are adapted to carry current to or from the outer sleeve assembly <NUM> which comprises a return electrode. It should be appreciated that conductive fluid can migrate into various parts of the hub <NUM> and it is necessary to prevent any migration of conductive fluid into the interface between the spring-loaded ball contacts 780a and 780b and the rotating contact ring <NUM>. Any migrating conductive fluid is effectively a return electrode and could cause a short circuit. To insure that there is no migration conductive fluid into contact with contact ring <NUM>, <FIG> and <FIG> illustrate a flexible seal <NUM> that has is flexible annular sealing elements 788a and 788b that are both proximal and distal from the rotating contact ring <NUM>. By the means, the chamber <NUM> in which the spring-loaded ball contacts 780a and 780b engage the contact ring <NUM> will remain fluid-tight.

Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration and the above description of the invention is not exhaustive. Specific features of the invention are shown in some drawings and not in others, and this is for convenience only and any feature may be combined with another in accordance with the invention. A number of variations and alternatives will be apparent to one having ordinary skills in the art.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The term "connected" is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening.

Claim 1:
A tissue resecting device (<NUM>) comprising:
an outer sleeve (<NUM>) having an axial bore (<NUM>) extending along a longitudinal axis from a proximal end to a distal end and opening to an outer window (<NUM>) near the distal end;
an inner sleeve (<NUM>) rotatably received in the axial bore (<NUM>) of the outer sleeve (<NUM>) and having an axial channel (<NUM>) adapted for communication with a negative pressure source;
a distal housing attached to a distal end of the inner sleeve (<NUM>), wherein the distal housing comprises an annular dielectric portion (<NUM>) and a circumferentially adjacent annular metal portion (<NUM>) having an inner window (<NUM>) with circumferentially spaced-apart sharp cutting edges that opens to the axial channel (<NUM>);
a first longitudinal member which comprises the annular dielectric portion (<NUM>);
a second longitudinal member which comprises the annular metal portion (<NUM>), wherein the first longitudinal member is coupled to the second longitudinal member, and wherein a proximal end (<NUM>) of an assembly of the first longitudinal member (<NUM>) and the second longitudinal member (<NUM>) is dimensioned for insertion into the axial channel (<NUM>) of the inner sleeve (<NUM>) and wherein the inner sleeve (<NUM>) engages with the first longitudinal member and the second longitudinal member to provide a connection around the proximal end; and
an active electrode (<NUM>) carried by the annular dielectric portion (<NUM>), wherein the inner window (<NUM>) is circumferentially spaced-part from the active electrode (<NUM>) and wherein the inner window (<NUM>) and the active electrode (<NUM>) rotate alternately into alignment with the outer window (<NUM>) as the inner sleeve (<NUM>) is rotated within the outer sleeve (<NUM>).