Abstract:
A medical for removing tissue from a patient includes an elongated probe with a working end. A pair of jaws is provided at the working end. The jaws may be closed for cutting and treatment of the tissue. Cutting may be effective through a sharpened cutting blade, and RF cutting blade, and similar cutting edges. The tissue may be remodeled using heat generated from passive heating elements on the jaws, active heating elements on the jaws, a PTCR heating element carried by the jaws, or resistive heaters on the jaws.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Provisional Application No. 61/559,519, filed Nov. 14, 2011, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to medical devices and techniques and more particularly relates to instruments that are adapted to transect joint tissue and electrosurgically remodel the cut edges of remaining tissue. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide an instrument working end capable of (i) transecting tissue and (ii) providing a controlled application of heat for remodeling the tissue edges that remain following the transecting step. 
     Additional objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. 
     In a first aspect of the present invention, methods for treating tissue, such as cartilage and other joint tissues, comprise clamping a selected tissue volume between a first jaw and second jaw. While the tissue is or remains clamped between the jaws, it is cut with a first cutting element disposed on at least one jaw and remodeled with a remodeling element disposed on at least one jaw. The cutting and remodeling elements may be on both jaws and may comprise different components disposed on either or both jaws. By “remodeling,” it is meant that the tissue will be heated in order to denature the collagen therein and will be reshaped or reformed in a manner which provides physiologic benefit when the treatment is completed. In exemplary embodiments, the tissue will be remodeled to receive a tapered edge which can have physiologic benefits, particularly in treatment of cartilage and other joint tissues. 
     In a second aspect, the present invention comprises a medical device for resecting and remodeling tissue. In particular, the device comprises an elongate probe with a working end and first and second “openable-closable” jaws operably connected to the working end of the probe. At least one of two jaws will have a first surface portion carrying a tissue cutting element. At least one of the two jaws, which may be the same or different than the jaw carrying the tissue cutting element, will carry a heat emitter for applying thermal energy for remodeling tissue. 
     In both the method and device aspects of the present invention, the tissue cutting element may comprise a sharp edge disposed about a perimeter of at least one jaw, such as a cutting blade which shears against an edge of the opposed jaw. Alternatively, the cutting element may comprise a radio frequency (RF) electrode which is carried on or over a perimeter of at least one jaw. 
     In both the method and device aspects of the present invention, the remodeling will be accomplished by application of heat to the tissue, preferably while the tissue remains clamped between the jaws. The heating may be provided by Joule heating, passive conductive heating, or both. Alternatively, the heating may result from passing RF current between first and second electrodes carried by one or both of the jaws where the RF current results in heating of the tissue. In a third example, the tissue heating may be achieved by passing current through a positive temperature coefficient of resistance (PTCR) material which results in a temperature-controlled heating depending on the nature of material. 
     In specific embodiments, the heat emitter may comprise a first tapered surface on one jaw and a second tapered surface on the other jaw. The tapered surfaces diverge in a laterally outward direction from the jaws so that the tissue, when clamped between the closed jaws, is reformed into an inward tapered tissue margin after the tissue was cut and heated by the device. 
     In still further specific embodiments of the present invention, the device may include means for removing the cut tissue from the treatment area. For example, the probe may be configured to provide further transport of the cut tissue in a proximal direction, for example within a channel extending through the probe. Optionally, a negative pressure source may be provided in order to draw the tissue approximately through the channel. Alternatively or additionally, a negative pressure may be provided at the remote of the channel in order to draw or pull the tissue approximately out of the probe. Alternatively or additionally, a positive pressure may be provided at the distal end of the channel in order to push tissue approximately through the channel 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and advantages of the present invention will be understood by reference to the following detailed description of the invention when considered in combination with the accompanying Figures, in which like reference numerals are used to identify like components throughout this disclosure. 
         FIG. 1A  is a view of a medical instrument corresponding to the invention. 
         FIG. 1B  is a perspective view of a working end of the instrument of  FIG. 1A  with first and second jaws having a cutting edge about a first perimeter and an energy delivery surface outward of the cutting edge for applying heat and pressure to engaged tissue. 
         FIG. 2A  is a sectional schematic view of the working end of  FIG. 1  taken along line  2 A- 2 A showing the first and second jaws being prepared to engage tissue in a method of using the working end of the invention. 
         FIG. 2B  is another sectional view of the working end of  FIG. 2A  showing the first and second jaws transecting tissue and applying heat and compression to remodel the remaining tissue edges outward of the transected tissue. 
         FIG. 2C  is a sectional view of remodeled tissue edges following the application of heat and compression. 
         FIG. 3  is another variation of working end similar to that of  FIG. 1  with an RF electrode cutting edge. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1A-1B , a medical instrument  200  is shown with a handle  202  and elongated introducer or shaft member  205  that carries the working end  210  and is adapted for transecting and remodeling tissue. In one embodiment, the instrument is adapted for arthroscopy wherein the shaft member  205  extending along axis  215  can have a diameter ranging from 3 mm to 8 mm. The working end  210  comprises an openable-closeable jaw assembly with first (upper) jaw  222   a  and second (lower) jaw  222   b  that close and engage tissue about axis  215 . The shaft member  205  can have a cylindrical or rectangular cross-section and can comprise a thin-wall tubular sleeve that extends from handle  202 . In one embodiment, the handle  202  has a lever arm  224  that is adapted to actuate a translatable, reciprocating member that functions as a jaw-closing mechanism as is known in the art. 
     In one embodiment shown in  FIG. 1B , jaw member  222   a  has a first or inner surface portion  225  extending around an interior tissue extraction channel  228  defined by the two jaws, wherein at least one tissue cutting element  232  is carried about a first surface portion  225 . In this variation, the cutting element is a sharp blade edge  232  carried by the upper jaw  222   a . The sharp blade edge  232  is configured for shearing tissue against the edge  235  of the extraction channel  228  in lower jaw  222   b . In another variation, both jaws can carry sharp blade edges that shear against each other to transect tissue. 
     In the embodiment of FIGS.  1 B and  2 A- 2 B, each jaw has a second surface portion  240  outward of the blade edge  232  and in upper jaw  222   a  edge  235  in lower jaw  222   b , where the second surface portion  240  is formed over a heat emitter  244  for applying thermal energy to engaged tissue for remodeling such tissue under pressure. The second surface portion  240  can have a gripping surface for gripping tissue, for example, a surface with fine ridges or an abrasive surface (not illustrated). In one variation, the second surface portions  240  in the opposing jaws are configured to define a tapered region that tapers toward the cut edges of the tissue as shown in  FIGS. 2B-2C . By applying heat through the heat emitter  244 , a tapered edge can be formed or “remodeled” into transected tissue margins  268  which can be beneficial in treatment of cartilage and other tissues, for example, any tissues which are formed at least partly of collagen and can be thermally denatured and effectively molded or remodeled. 
     In one variation as depicted in FIGS.  1 B and  2 A- 2 B, the heat emitters  244  can comprise PTCR (positive temperature coefficient of resistance) elements that are disposed on or within a jaw body. Suitable materials for forming the PTCT elements are described, for example, in U.S. Pat. Nos. 7,309,849; 7,087,054; 7,955,331; 8,075,555; and 8,192, 428, the full disclosures of which are incorporated herein by reference. The PTCR elements  244  can be positioned within an insulated layer if the jaw body is a conductive material or can be embedded in a plastic or other insulative jaw body. The PTCR elements comprise constant temperature heaters in which electrical energy provided by an electrical source  250  and controller  255  resistively heats the PTCR material to a predetermined temperature level at which the material switches between electrically conductive and non-conductive. In  FIG. 1B , it can be understood that positive and negative electrical leads extend to each PTCR element in the upper and lower jaws. The PTCR material can be configured to have a constant or switching temperature that is suited for remodeling collagenous tissue under pressure, such 55° C. or less, 56° C., 57° C., 58° C., 59° C., 60° C., 61° C., 62° C., 63° C., 64° C., 65° C., 66° C., 67° C., 68° C., 69° C., 70° C., 71° C., 72° C., 73° C., 74° C., 75° C., 76° C., 77° C., 78° C., 79° C. or 80° C. At such temperatures, collagen fibrils will denature, unwind and can be remodeled under pressure wherein thermal relaxation will result in a remodeled collagen shape. 
     Referring to  FIG. 1B , the diameter or cross-section of the shaft  205  can be from about 3 mm to 8 mm. The diameter D of the extraction channel can range from about 2.5 mm to 7.5 mm. A typical device for use in arthroscopy has a diameter of about 5 mm. The width W of the second surface portion  240  can range from about 1 mm to 4 mm. The length L of the jaws can range from about 3 mm to 5 mm as in a type of ‘punch’ currently used in trimming cartilage, meniscus etc. or the jaws can be longer, for example 5 mm to 20 mm in length. In  FIG. 1   b , the jaws  222   a  and  222   b  are shown with the upper jaw pivoting around pin  248  but any type of jaw configuration is possible. 
     In  FIG. 1B , it can be seen that a negative pressure source  260  communicates with the tissue extraction channel  228  which is configured for aspirating transected tissue proximally through the channel  228  in the instrument to a collection reservoir. Typically, the instrument working end  210  would be operated in a saline fluid environment, and in one variation the aspiration function can operate only when the jaws are closed. Alternatively, the aspiration mechanism can be manually turned ON when needed by the physician. 
     In another variation, the interior of the jaws can be configured with an electrode arrangement to provide for explosive vaporization of captured saline when the jaws are in the closed position to expel the transected tissue in the proximal direction, generally as disclosed in co-pending U.S. patent application Ser. No. 13/277,913, filed Oct. 20, 2011, titled TISSUE EXTRACTION DEVICES AND METHODS, now U.S. Pat. No. 8,512,326. 
       FIGS. 2A-2C  show a method of using the working end of  FIG. 1B  to cut and remodel tissue. In  FIG. 2A , a transverse sectional view of the jaws  222   a  and  222   b  can be seen in an open position preparing to engage tissue  265 , which for example can be cartilage or meniscus.  FIG. 2B  depicts the jaws  222   a  and  222   b  closing on the tissue  265  with the sharp blade edge  232  cutting the tissue and capturing transected tissue  266  in the interior channel  228 . At the same time,  FIG. 2B  illustrates heat being applied to the tissue margins  268  from the PTCR emitters  244  to remodel the engaged tissue.  FIG. 2C  shows the tissue margins  268  after heating and compression wherein the thermal remodeling can provide a tapered tissue margin which is needed in treatments of joint tissue. 
     In another embodiment, referring to  FIG. 3 , the cutting edge can comprise an RF electrode  270  that creates a plasma for cutting tissue. In  FIG. 3 , the RF electrode  270  can cooperate with opposing polarity electrode  275  in the interior of the lower jaw. In this embodiment, the heat emitters  277   a  and  277   b  in the respective jaws  222   a  and  222   b  can comprise opposing polarity electrodes or PTCR elements as described previously. 
     In general, the device corresponding to the invention comprises an elongated probe with a working end  210  having openable-closeable first and second jaws wherein at least one jaw has a first surface portion carrying a tissue cutting element and a second surface portion outward of the first surface portion carrying a heat emitter configured for applying thermal energy for remodeling tissue, and not for cutting tissue. The independent cutting element can comprise a blade edge or at least one RF electrode. 
     In general, a method of treating joint tissue comprises providing an elongated probe with a working end having openable-closeable first and second jaws having a first inner tissue-cutting perimeter and a second outer tissue-remodeling perimeter, clamping tissue between the first and second jaws and cutting tissue engaged within the first perimeter and remodeling tissue engaged intermediate the second and first perimeters. The cutting step can be accomplished by a sharp edge at the first perimeter of at least one jaw or an RF electrode edge at the first perimeter of at least one jaw. The remodeling step is accomplished at least in part by heating tissue captured intermediate the second and first perimeters. The heating step can be provided by at least one of Joule heating and passive conductive heating. The method further comprises capturing cut and mobilized tissue within a channel within at least one jaw, and transporting tissue in the proximal direction within a channel extending through the elongated probe. Typically, the cut and mobilized tissue is transported under the influence of fluidic pressure, which can be negative pressure that pulls the tissue proximally and/or positive pressure that pushes the tissue proximally. 
     Although particular embodiments of the present invention have been described above in detail, it will be understood that this description is merely for purposes of illustration and the above description of the invention is not exhaustive. Specific features of the invention are shown in some drawings and not in others, and this is for convenience only and any feature may be combined with another in accordance with the invention. A number of variations and alternatives will be apparent to one having ordinary skills in the art. Such alternatives and variations are intended to be included within the scope of the claims. Particular features that are presented in dependent claims can be combined and fall within the scope of the invention. The invention also encompasses embodiments as if dependent claims were alternatively written in a multiple dependent claim format with reference to other independent claims.