Patent Publication Number: US-2007123850-A1

Title: Power-assisted liposuction instrument with cauterizing cannula assembly

Description:
RELATED CASES  
      The present Application is a Continuation of U.S. application Ser. No. 10/702,215 filed Sep. 26, 2006; which is a Continuation of application Ser. No. 09/993,297 filed Nov. 19, 2001, now U.S. Pat. No. 6,652,522; which is a Continuation of application Ser. No. 08/976,073, filed Nov. 21, 1997, now U.S. Pat. No. 6,346,107, which is a Continuation-in-Part of application Ser. No. 08/882,927 filed Jun. 26, 1997, now U.S. Pat. No. 5,795,323, which is a Continuation of application Ser. No. 08/307,000 filed Sep. 16, 1994, now U.S. Pat. No. 5,643,198, which is a Continuation of application Ser. No. 07/627,240 filed Dec. 14, 1990, now U.S. Pat. No. 5,348,535. Each said Application is incorporated herein by reference as if set forth in its entirety. 
    
    
     FIELD OF INVENTION  
      The present invention relates generally to a method and apparatus for performing liposuction and more particularly to a method and apparatus for performing liposuction in a mechanically assisted manner using powered expedients.  
     BRIEF DESCRIPTION OF THE PRIOR ART  
      Suction lipectomy, commonly known as liposuction or lipoxheresis, is a well known surgical procedure used for sculpturing or contouring the human body to increase the attractiveness of its form. In general, the procedure involves the use of a special type of curet known as a cannula, which is operably connected to a vacuum source. The cannula is inserted within a region of fatty tissue where removal thereof is desired, and the vacuum source suctions the fatty tissue through the suction aperture in the cannula and carries the aspirated fat away. Removal of fat cells by liposuction creates a desired contour that will retain its form.  
      Presently, there are two widely accepted techniques of liposuction and each may be practiced using a conventional liposuction cannula. The first and most common method proposed by Yves-Gerard Illouz and described in the paper “Illouz&#39;s Technique of Body Contouring by Lipolysis” in Vol. III, No. 3, July 1984 of Clinics in Plastic Surgery, involves making regular tunnels at a depth of at least 1 centimeter under the skin. According to this method, one or two insertions are made, with radial excursions of the cannula into the fatty tissue of the patient. The result is a multitude of concomitant sinuses formed below the subcutaneous fatty tissue, leaving intact as far as possible the connections between the skin and underlying tissue, thereby retaining the blood vessels, the lymphatics and the nerve endings. The second method is the original liposuction procedure proposed by U. K. Kesselring, described in “Body Contouring with Suction Lipectomy”, in Vol. 11, No. 3, July 1984, Clinics in Plastic Surgery. According to the technique, an entire layer of regular, deep fat is removed by aspiration through the cannula, leaving a smooth, deep surface of the residual panniculus. The space thus created is then compressed, optimally followed by skin retraction.  
      Both of these prior art liposuction techniques require that the surgeon push and pull the entire cannula back and forth almost twenty times for each insertion made. Typically, twenty to thirty tunnels are made. This is necessary to ensure even removal of fat in the targeted region. During this procedure, the surgeon typically massages the flesh in the area of the aperture in the cannula, while at the same time, thrusting the rod in and out of the tunnel. Due to the trauma involved during the procedure, the patients&#39; skin, turns black and blue for several weeks. Due to the physically exacting nature of the procedure, the surgeon typically comes out of an operating room extremely tired and suffers from muscular fatigue, which prevents him from performing, for some time thereafter, the delicate operations involved in ordinary plastic surgery.  
      Recently, the use of a “guided cannula” has been proposed by R. de la Plaza, et al., described in “The Rationalization of Liposuction Toward a Safer and More Accurate Technique,” published in Vol. 13, Aesthetic Plastic Surgery, 1989. According to the technique, a cannula is used in conjunction with an outer guide sheath through which the cannula can slidably pass while held in place by the handle portion of guide sheath. Once the cannula and its sheath have been introduced into the fatty tissue, the sheath guide remains in the tunnel and guides successive introductions of the cannula, keeping it in the same tunnel. While the use of this liposuction technique offers some advantages over the conventional unguided liposuction cannulas, the guided cannula nevertheless suffers from several significant shortcomings and drawbacks. In particular, the guided cannula requires manually thrusting the cannula through the guide sleeve repeatedly for each tunnel. Although this is a less physically demanding procedure, the surgeon must thrust the cannula even more times through each tunnel to achieve the desired effect and hence is still easily fatigued and prevented him from performing, for some time thereafter, the delicate operations involved in ordinary plastic surgery.  
      In attempts to solve the above-described problem, U.S. Pat. Nos. 4,735,605, 4,775,365 and 4,792,327 to Swartz disclose an assisted lipectomy cannula having an aspiration aperture, which effectively travels along a portion of the length of the cannula, thereby obviating the necessity of the surgeon to repeatedly push the cannula in and out of the patients&#39; subcutaneous tissue where fatty tissue is to be removed. While this assisted lipectomy cannula can operate on either air or electric power, it nevertheless suffers from several significant shortcomings and drawbacks. In particular, the device requires an outer tube with an elongated slot and a inner tube having a spiral slot which must be rotated inside the outer tube to effectuate a traveling aspiration aperture. In addition to the device&#39;s overall construction posing difficulties in assembly, cleaning and sterilization, use with a variety of cannulas and highly effective fat aspiration does not appear possible.  
      Accordingly, there is a great need in the art for a mechanically assisted, lipectomy cannula which overcomes the shortcomings and drawbacks of prior art lipectomy apparatus.  
     OBJECTS AND SUMMARY OF THE PRESENT INVENTION  
      Thus, it is a primary object of the present invention to provide an improved method and apparatus for performing liposuction which assists the surgeon in the removal of fat and other subcutaneous tissue (such as but not restricted to gynecomastia) from surrounding tissue, with increased safety and without promoting physical fatigue.  
      It is another object of the present invention to provide such an apparatus in the form of a hand-holdable liposuction instrument, having a cannula assembly, in which the location of the aspiration aperture is periodically displaced as the inner or outer cannulas undergo a sliding movement relative to the hand-holdable housing.  
      It is a further object to provide such a liposuction instrument in which the rate of reciprocation and the amount of excursion of the aspiration aperture, are selectively adjustable by the surgeon during the course of operation.  
      An even further object of the present invention is to provide such a liposuction instrument, which can be driven by air or electricity.  
      A further object of the present invention is to provide such a liposuction instrument, in which the cannula assembly can be simply detached from the hand-holdable housing for ease of replacement and/or sterilization.  
      An even further object of the present invention is to provide an improved method of performing liposuction, in which one of the cannulas of the cannula assembly is automatically reciprocated back and forth relative to the hand-holdable housing, to permit increased control over the area of subcutaneous tissue where fatty and other soft tissue is to be aspirated.  
      Another object of the present invention is to provide a power-assisted liposuction instrument, wherein means are provided along the cannula assembly to effect hemostasis during liposuction procedures and the like.  
      Another object of the present invention is to provide such a power-assisted liposuction instrument, wherein the hemostasis means is realized using RF-based electro-cauterization.  
      Another object of the present invention is to provide such a power-assisted liposuction instrument, wherein RF-based electro-cauterization is carried out by providing electro-cauterizing electrodes along the cannula assembly and supplying to these electrodes RF signals of sufficient power to achieve electro-coagulation and thus hemostasis during liposuction procedures.  
      Another object of the present invention is to provide such a power-assisted liposuction instrument, wherein the outer cannula is realized from a non-conductive material and electro-cauterizing electrode elements are inserted within the aspiration apertures thereof and electrical wiring embedded along the outer cannula and connected to a contact pad embedded within the base portion thereof and wherein the inner cannula is made from an electrically conductive material which establishes electrical contact with contact brushes, mounted within the central bore of the base portion of the inner cannula.  
      Another object of the present invention is to provide such a power-assisted liposuction instrument, wherein RF supply and return signals are coupled to the cannula assembly by way of the base portion of the outer cannula.  
      Another object of the present invention is to provide a power-assisted liposuction instrument, wherein RF-based electro-cauterization is realized using electrically conductive inner and outer cannulas which are electrically isolated by way of thin Teflon coatings applied to the outer surface of the inner cannula and/or the interior surface of the outer cannula.  
      Another object of the present invention is to provide a power-assisted, liposuction instrument, wherein ultrasonic energy of about 50 KHZ is coupled to the inner cannula in order to effect protein coagulation about the aspiration apertures and thus achieve electro-cauterization (i.e., hemostasis) during liposuction procedures.  
      Another object of the present invention is to provide such a power-assisted liposuction instrument, wherein such ultrasonic energy is produced by piezoelectric crystals embedded within the base portion of the inner cannula and driven by electrical signals having a frequency of about 50 KHZ.  
      Another object of the present invention is to provide such a liposuction instrument, wherein the electrical drive signals are supplied to the piezoelectric transducers by way of a pair of electrically conductive rails embedded within the interior surface of the cannula cavity of the hand-holdable housing of the liposuction device.  
      Another object of the present invention is to provide a way of carrying out RF-based cauterization within a cannula assembly, wherein the operating surgeon is enabled to perform lipolysis by driving the piezo-electric transducers within the base portion of the inner cannula with signals in the frequency range of about 20-25 KHZ.  
      These and other objects of the present invention will become apparent hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      For a fuller understanding of, the objects of the present, invention, reference is made to the detailed description of the illustrative embodiments which are to be taken in connection with the accompanying drawings, wherein:  
       FIG. 1A  is a perspective view of a first embodiment of the liposuction device of the present invention;  
       FIG. 1B  is a cross-sectional view of the liposuction device of the present invention taken along line  1 B- 1 B of  FIG. 1A ;  
       FIG. 1C  is an elevated end view of the liposuction device of the present invention illustrated in  FIG. 1A , showing the electro-cauterizing cannula assembly thereof retained within the cannula cavity of its hand-holdable housing, and alternatively with the hingedly connected housing cover panel disposed in an open position for removal of the cannula assembly therefrom;  
       FIG. 2A  is a perspective, partially broken away view of the electro-cauterizing, cannula assembly of, the present invention installed in the liposuction instrument of  FIGS. 1A through 8C , in which the electrically-conductive inner cannula is adapted to freely undergo sliding movement within the stationary electrically non-conductive outer cannula while electro-cauterization is performed about the aspiration apertures thereof under the control of the surgeon;  
       FIG. 2B  is a perspective view of the distal end of the inner cannula shown in  FIGS. 1A, 1B  and  2 A;  
       FIG. 2C  is a cross-sectional view of the electrically-conductive inner cannula taken along line  2 C- 2 C of  FIG. 2B ;  
       FIG. 2D  is a perspective, partially broken away view of the electrically non-conductive outer cannula shown in  FIGS. 1A , LB and  2 A;  
       FIG. 2E  is a cross-sectional, view of the electro-cauterizing assembly, taken along line  2 E- 2 E of  FIG. 2A ;  
       FIG. 2F  is a cross-sectional view of the base portion of the electro-cauterizing cannula assembly of the present invention taken along line  2 F- 2 F in  FIG. 2A ;  
       FIG. 3A  is a plan view of a cauterizing electrode of the present invention adapted for insertion within the elongated aperture of the electrically non-conducting outer cannula;  
       FIG. 3A   1  is an elevated side view of the cauterizing electrode of the present invention taken along line  3 A 1 - 3 A 1  of  FIG. 3A ;  
       FIG. 3A   2  is an elevated side view of the cauterizing electrode of the present invention taken along line  3 A 2 - 3 A 2  of  FIG. 3A . 1 ;  
       FIG. 3B  is a perspective view of the electrically-conductive collar and brush device of the present invention which inserts with the central bore formed in the base portion of the electrically non-conductive outer cannula of the present invention shown in  FIG. 2D ;  
       FIG. 3B   1  is a cross-sectional, view of the electrically-conductive collar and brush device of the present invention taken along line  3 B 1 - 3 B 1  of  FIG. 3B ;  
       FIG. 4A  is a cross-sectional view of a portion of a second embodiment of the liposuction device of the present invention, illustrating an alternative outer cannula retention means;  
       FIG. 4B  is a cross-sectional view of a portion of a second embodiment of the liposuction device of the present invention, illustrating an alternative inner cannula retention means;  
       FIG. 5  is a cross-sectional view of third embodiment of the liposuction device of the present invention, illustrating a means for controlling the mount of excursion of the aspiration aperture along the cannula assembly;  
       FIG. 6A  is a cross-sectional view of a sixth embodiment of the liposuction device of the present invention, illustrating the use of a pair of gas driven piston-type motors and a mechanically-operated gas flow control device disposed in its first state of operation;  
       FIG. 6B  is a cross-sectional view of the liposuction device of the present invention taken along line  6 B- 6 B of  FIG. 6A ;  
       FIG. 6C  is a perspective view of the preferred embodiment of the mechanically-operated gas flow control device illustrated in  FIG. 6A ;  
       FIG. 6D  is a cross-sectional view of the gas flow control device of the present invention taken along line  6 D- 6 D of  FIG. 6C .  
       FIG. 7A  is a perspective, partially broken away view of a second snap-fit type inner cannula intended for use with the second embodiment of the liposuction device of the present invention;  
       FIG. 7B  is a cross-sectional view of the outer cannula of the present invention taken along lines  7 B- 7 B of  FIG. 7A ;  
       FIG. 8  is a perspective, partially broken away view of a snap-fit type outer cannula intended for use in connection with the second embodiment of the liposuction device of the present invention;  
       FIG. 9A  is a plan cross-sectional view of a seventh embodiment of the liposuction device of the present invention, having a hand-holdable housing realized in the form of a pistol-shaped structure having detachable barrel and handle portions;  
       FIG. 9B  is a cross-sectional, partially broken away view of the liposuction device of the present invention taken along line  9 A- 9 B of  FIG. 9A , showing the cam mechanism of the present invention;  
       FIG. 9C  is an elevated cross-sectional view of the liposuction device of the present invention, taken along line  9 C- 9 C of  FIG. 9A , showing the inner cannula disposed at a first position within the cannula cavity of the hand-holdable housing, and the rotary motor and speed control unit in the handle portion thereof;  
       FIG. 9D  is a cross-sectional view of a portion of the inner cannula excursion control means shown in  FIGS. 9B and 9C ;  
       FIG. 9E  is a cross-sectional view of the liposuction device of the present invention taken along line  9 E- 9 E of  FIG. 9A , showing the rotary drive wheel of the cam mechanism in operable association with the actuation element which projects through the cannula cavity and is engaged in the slotted base portion of the inner cannula, and also showing in phantom lines the cover panel of the barrel portion disposed in an open configuration permitted insertion or removal of the inner and outer cannulas of the present invention;  
       FIG. 9F  is an elevated partially broken away rear view of the barrel portion of the liposuction device taken along line  9 F- 9 F of  FIG. 9A ;  
       FIG. 10  is a cross-sectional view of another illustrative embodiment of the liposuction device of the present invention, wherein a liposuction device of the present invention is provided, having a double-acting air-powered cylinder with a magnetically-coupled actuator and wherein the electro-cauterizing cannula assembly of the present invention is installed;  
       FIG. 10A  is a cross-sectional schematic diagram of the air flow control device employed in the liposuction device shown in  FIG. 10 , in which the control valve thereof is mechanically-linked to the reciprocating piston contained within the cylinder-style reciprocator within the housing of the liposuction device;  
       FIG. 11A  is a perspective, partially broken away view of a the electro-cauterizing cannula assembly of the present invention in the liposuction instrument of  FIG. 10  in which the electrically-conductive inner cannula is adapted to freely undergo sliding movement within the stationary electrically non-conductive outer cannula while electro-cauterization is performed about the aspiration apertures thereof under the control of the surgeon;  
       FIG. 11B  is a perspective view of the distal end of the inner cannula shown in  FIG. 11A ;  
       FIG. 11C  is a cross-sectional view of the electrically-conductive inner cannula taken along line  11 C- 11 C of  FIG. 11B ;  
       FIG. 11D  is a perspective, partially broken away view of the electrically non-conductive outer cannula shown in  FIG. 11A ;  
       FIG. 11E  is a cross-sectional view of the electro-cauterizing cannula assembly taken along line  11 E- 11 E of  FIG. 11A ;  
       FIG. 11F  is a perspective view of the base portion of the electrically-conductive inner cannula shown in  FIG. 11  showing an electrical contact pad embedded in the outer surface thereof for conducting the conductive rail embedded in the wall surface of the cannula cavity;  
       FIG. 11G  is a cross-sectional view of the liposuction instrument taken along line  11 G- 11 G of  FIG. 10 ;  
       FIG. 12A  is a plan view of a cauterizing electrode of the present invention adapted for insertion within the elongated aperture of the electrically non-conducting outer cannula shown in  FIG. 11 ;  
       FIG. 12A   1  is an elevated side view of the cauterizing electrode of the present invention taken long line  12 A 1 - 12 A 1  of  FIG. 12A ;  
       FIG. 12A   2  is an elevated side view of the cauterizing electrode of the present invention taken along line  12 A 2 - 12 A 2  of  FIG. 12A   1 ;  
       FIG. 13A  is a perspective, harshly broken away view of the electrically-conductive outer cannula employed in an alternative embodiment of the electro-cauterizing cannula assembly utilizable in the liposuction device of the present invention with suitable modifications;  
       FIG. 13B  is a perspective view of a distal end of the inner cannula shown in  FIG. 13A ;  
       FIG. 13C  is a cross-sectional view of the electrically conductive inner cannula taken along line  13 C- 13 C of  FIG. 13B ;  
       FIG. 13D  is a perspective harshly broken away view of the electrically conductive outer cannula shown in  FIG. 13A , over which an electrically insulating coating such as teflon is applied to the exterior surface thereof;  
       FIG. 14  is a cross-sectional schematic diagram of an alternative embodiment of the electro-cauterizing liposuction instrument of the present invention, wherein the reciprocation means is realized using a cylinder-style actuator powered by a supply of pressurized air;  
       FIG. 14A  is a schematic cross-sectional view of the airflow control device employed within the liposuction instrument of  FIG. 14 ;  
       FIG. 14B  is a perspective, harshly broken away view of the electrically-nonconductive outer cannula employed in alternative embodiment of the elector-cauterizing cannula assembly utilized in the liposuction instrument of  FIG. 14 ;  
       FIG. 14C  is a perspective view of a distal end of the inner cannula shown in  FIG. 14B ;  
       FIG. 14D  is a perspective harshly broken away view of the electrically nonconductive outer cannula shown in  FIG. 14B , over which an electrically insulating coating such as teflon is applied to the exterior surface thereof;  
       FIG. 14E  is a perspective view of the base portion of the inner cannula used in the cannula assembly of  FIG. 14B , wherein an electrical contact pad is embedded in the side wall surface of the base portion for engagement with an electrically conductive rail embedded within the interior wall surfaces of the cannula cavity of the liposuction instrument.  
       FIG. 14F  is a cross sectional view of the base portion of the inner cannula taken along line  14 F- 14 F in  FIG. 14E , showing a plurality of piezo-electrical transducers arranged about the lumen of the inner cannula for producing and conducting ultrasonic energy signals for propagation along the length of the inner cannula; and  
       FIG. 14G  is a cross sectional view of the liposuction instrument of  FIG. 14  taken along line  14 G- 14 G of  FIG. 14 , showing a pair of diametrically opposed electrically conductive rails embedded within the interior wall surfaces of the cannula cavity of the liposuction instrument, which establish electrical contact with a pair of electrical contact pads embedded within the base portion of the base portion of the inner cannula and are connected to the array of piezo-electric transducers mounted about the outer lumen of the inner cannula. 
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS  
      With reference to  FIGS. 1A through 3D , the first embodiment of the liposuction device of the present invention will be described. In general, liposuction device  1 A comprises a hand-holdable housing  2 , a detachable electro-cauterizing cannula assembly  4  having inner and outer cannulas  4  and  5 , and a reciprocation means  6  for causing inner cannula  4  to reciprocate means  6  for causing inner cannula  4  to reciprocate relative to outer cannula  5 , which is stationarily disposed with respect to housing  2 . This arrangement effectuates periodic displacement of the general location of aspiration along the cannula assembly through the reciprocating movement of inner cannula  4 , while permitting electro-cauterization of aspirated tissue during operation of the liposuction device.  
      As illustrated in greater detail in  FIGS. 1B , and  2 A through  2 E, the electro-cauterizing cannula assembly  3  of the present invention comprises an electrically-conductive inner cannula  4  and a non-conductive outer cannula  5 , each comprising hollow inner and outer tubes with distal and proximal ends  4 A,  4 B and  5 A,  5 B, respectively.  
      As shown in  FIGS. 2B and 2C , the outer cannula  5  comprises a hollow outer tube having a distal end  5 A and a proximal end  5 B. Four outer aspiration (i.e., suction) apertures generally indicated by reference numerals  8 A,  8 B,  8 C and  8 D are provided on the distal end of the inner cannula. As shown, elongated apertures generally indicated by reference numerals  8 A,  8 B,  8 C and  8 D are provided on the distal end of the inner cannula. As shown, elongated apertures  8 A,  8 B,  8 C and  8 D terminate at a predetermined distance away from outer cannula tip  5 C, which is essentially blunt for purposes of safety. In general, the length of each of these elongated outer apertures is substantially longer than the longitudinal extent of each ratio of these lengths is (about 1 to 4); however, in other embodiments, this ratio may differ as desired or required in a given application. In a typical embodiment, the length of these elongated outer apertures would be within the range of, for example, two to six inches, commensurate with the amount of displacement to be achieved by each inner aperture.  
      As illustrated in  FIG. 1B , an outer cannula base  17  extends from the proximal end of outer tube  5 . The outer cannula base  17  comprises a cylindrical structure having a central bore  18 , through which distal tip  4  and body of inner cannula  4  can freely pass. The outer cannula base  17  of the illustrative embodiment includes a flanged portion  19  which fits within an annular recess  18  formed in cannula cavity  20  of the hand-holdable housing.  
      As shown in  FIG. 2B , an inner cannula base  10  extends from the proximal end of inner tube  4 . As shown, the inner cannula base  10  comprises a cylindrical structure having an outlet port  11  formed in its remote end. The inner cannula base  10  of the illustrative embodiment includes a notch or slot  12  formed in its central most portion. As will be described in greater detail hereinafter, notch  12  functions to releasably receive an extensional portion  13  of actuation element  37 , in order to actuate reciprocation of inner cannula  4  within housing  2 . As illustrated in  FIG. 2B , inner cannula  4  has a continuous passageway  14 , which extends from inner aspiration opening  9  to outlet port  11 . As shown in  FIGS. 2B and 2C , the inner aspiration apertures originate between the distal tip portion  4 C. As shown, elongated apertures  16 A,  16 B,  16 C and  16 D terminate at a predetermined distance away from outer cannula tip  5 C, which is essentially blunt for purposes of safety. In general, the length of each of these elongated inner apertures is substantially longer than the longitudinal extent of each respective outer aperture. In the illustrated embodiment, the ratio of these lengths is about 1 to 4; however, in other embodiments, this ratio may differ as desired or required in a given application. In a typical embodiment, the length of these elongated apertures would be within the range of, for example, two to six inches, commensurate with the amount of displacement to be achieved by each outer aperture with its electro-cauterizing element.  
      While not shown, a conventional vacuum source is connected to outlet port  11 , preferably using optically transparent, semi-flexible tubing  15 . With this arrangement, aspirated fat tissue can be suctioned through apertures  8 A,  8 B,  8 C and  8 D and opening  9  and transported along passageway  14  to a reservoir device (not shown), operably associated with the vacuum source.  
      As illustrated in  FIGS. 2A and 2E , electrically-conductive cauterizing electrodes  160 A,  160 B,  160 C and  160 D are inserted about the perimeter of outer aspiration apertures  16 A,  16 B,  16 C, and  16 D, respectively, and fastened thereto by snap-fitting, adhesive or like means. As shown in FIGS.  3 A,  3 A 1 , and  3 A 2 , each electrically-conductive electrode comprises: a sidewall portion  161  which circumferentially extends about the perimeter of the respective aspiration aperture formed in the outer cannula; an opening  162  for permitting aspirated tissue and fat and the like to flow therethrough into the interior of the inner cannula; and a circumferential flange  163  substantially perpendicular to sidewall portion  161  and adapted to fit within a recessed groove  164  extending about the upper outer surface of the respective outer aspiration aperture formed in the electrically non-conductive outer cannula. In the illustrative embodiments, cauterizing electrodes  160 A through  160 D are made from stainless steel, brass, gold or any other electrically-conductive material that is suitable for contact with human tissue during liposuction and like surgical procedures.  
      As shown in  FIG. 2D , the base portion of the outer cannula is provided with a pair of spaced apart recesses  165 A and  165 B for receiving and securing a first and second electrically-conductive contact pads  166 A and  166 B, respectively. A first groove  167  is formed within the outer surface of the outer cannula  5  and base portion  19  in order to receive a first length of wiring  168 , which establishes electrical contact between the set of cauterizing electrodes  160 A through  160 D and an electrically-conductive contact pad  166 B. Similarly, a second groove  169  is formed within the outer surface of the outer cannula and base portion  19  in order to receive a second length of electrical wiring  170  which establishes electrical contact between the set of cauterizing electrodes  160 A through  160 D and second electrically-conductive contact pad  166 A. A sealing material such as melted plastic can be used to close off the grooves  167  and  169  once the electrical wiring has been recessed within the groove. Alternatively, a thin, outer plastic cannula sleeve having an inner diameter slightly greater than the outer diameter of outer cannula  4  can be slid thereover and secured to the base portion thereof  19  using screw-threads, snap-fit fastening, ultrasonic-welding, adhesive or the like. When completely assembled, electrically-isolated contact pads  166 A and  166 B are shown in  FIG. 2A . It is understood however, that contact elements  166 A and  166 B can be mounted elsewhere in the base portion of the outer cannula.  
      As shown in  FIG. 2A , an electrically-conductive collar and brush device  171  shown in FIGS.  3 B and  3 B 1  is inserted within the central bore formed in the base portion  19  of the electrically non-conductive outer cannula. The collar and brush device  171  comprises a cylindrical tube  172  made from electrically-conductive material (e.g., stainless steel) having an outer diameter that is slightly less than the diameter of the central bore formed through the base portion of the inner cannula. As shown in FIGS.  3 B and  3 B 1 , a pair of diametrically-opposed leaf-like electrical contact elements  173 A and  173 B project inwardly from the cylindrical walls of the device towards its axial center. As best shown in  FIG. 2F , the function of electrical contact elements  173 A and  173 B is to establish electrical contact between second contact pad  166 A (on base portion  10 ) and electrically conductive inner cannula  4  when the inner cannula is slid through the central bore  18  of the outer cannula, as shown in  FIG. 2A . A small annular flange  174  is formed on one end of the cylinder  172  to delimit the depth of its insertion. A small connector tab  175  is connected to flange  174 .  
      As shown in  FIG. 2E , the sidewall portion  161  of each cauterizing electrode  160 A through  160 D is of sufficient width (w g ) to provide a gap region  175  between (i) the electrically-conductive inner cannula  4  adjacent to the electrode and (ii) the sidewall portion  161  thereof. Preferably, the width of each gap  175  is selected so as to minimize electrical arcing (i.e. sparking) between each electrode  160  and the electrically conductive inner cannula  4  when an RF signal of, for example, about 500 kHZ at 800 Volts is applied thereacross during electro-cauterization.  
      As shown in  FIG. 1B , contact pas  166 A and  166 B establish electrical contact with conductive elements  176 A and  176 B embedded in the hand-holdable housing and are embedded within recesses formed in the base portion  19  of the outer cannula assembly. The conductive elements  176 A and  176 B are connected to the RF supply and RF return signal terminals  177 A and  177 B of RF generator  178 . In the preferred embodiment, RF generator  178  is realized as the Instant Response™ Electrosurgical Generator (Model Force FX) by ValleyLab International, a subsidiary of Pfizer, Inc. This Electrosurgical Generator can be easily connected to the electro-cauterizing electrodes hereof by electrical cabling  179  in order to drive the same with bipolar outputs produced from the Electrosurgical Generator. Notably, the Instant Response™ Electrosurgical Generator  178  includes three bipolar output modes, namely: Low/Precise; Medium/Standard; and Macrobipolar.  
      In order to maintain inner aspiration apertures  8 A,  8 B,  8 C and  8 D aligned with outer aspiration apertures  16 A,  16 B,  16 C and  16 D, respectively, and thus ensure partial registration therebetween, the distal end of the inner and outer tubes are provided with a keying system. In the illustrated embodiment, the keying system comprises a keying element  4 D disposed on the outer surface of the inner cannula, before distal tip  4 C. Keying element  4 D can be a rigid or flexible element that slides within an elongated outer aperture (e.g.,  16 B) and prevents axial rotation between cannulas  4  and  5  as they undergo relative reciprocation. To assemble cannula assembly  3 , distal tip  4 C of the inner cannula is inserted through bore  18  in outer cannula base  17  so that the distal end of inner cannula  4 A is slidably received within outer cannula  5 , as shown in  FIG. 3A . In this configuration, keying element  4 D is received and guided within elongated aperture  8 B′ as shown. In this general configuration, cannula assembly  3  is installed within cannula cavity  20  by first opening housing cover  21 , shown in  FIG. 1C . Then outer cannula base flange  17  is inserted within annular recess  19  and actuation extension  13  within inner cannula base notch  12 . Thereafter, housing cover  21  is closed shut and liposuction device  1 A is ready for operation. A conventional vacuum source is then connected to outlet port  11 , preferably using optically transparent, semi-flexible tubing  15 . With this arrangement, fatty tissue, aspirated through apertures  8 A/ 16 B,  8 B/ 16 B and  8 C/ 16 C and  8 D/ 16 D and opening  9 , can be transported through passageway  14  to a reservoir device (not shown), operably associated with the vacuum source.  
      As shown in  FIG. 1A , the gross geometry of housing  2  is preferably that of an ellipsoid, however, other geometries such as, for example, a cylindrical structure, can be used in practice in the present invention. Housing  2  contains cannula cavity  20 , which extends along the entire longitudinal extent of the hand-holdable housing. In the illustrated embodiment, cannula cavity  20  has generally cylindrical bearing surfaces  22 , which match the outer bearing surface  23  of inner cannula base  10 , to permit sliding movement of inner cannula  3  within cavity  20 . While cylindrical bearing surfaces have been selected in the illustrated embodiment, use of other forms of bearing surfaces (e.g., rectangular or triangular) is contemplated. To minimize friction, bearing surfaces  22  and  23  may be coated with a Teflon® or functionally equivalent coating, to facilitate easy sliding of inner cannula base  10  within cavity  20  with low wear. As illustrated in  FIG. 1B , cannula cavity  20  also includes annular recess  19 , into which annular base flange  19  is adapted to be received in order to render the outer cannula essentially stationary with respect to hand-holdable housing  2 .  
      As shown in  FIG. 1B , electrical contact pads  176 A and  176 B are embedded within surface-recesses formed within the wall surfaces of the annular recess  19 . Preferably, electrically-conductive contact pads  176 A and  176 B are made from electrically conductive material having a shape which is similar to the shape of electrically conductive pads  166 A and  166 B that are embedded within the outer surface of the base portion of the outer cannula  5 . When the cannula assembly of this embodiment is installed within the hand-holdable housing, the electrical contact pads  166 A and  166 B on the base portion of the outer cannula will automatically establish electrical contact with electrical contact pads  176 A and  176 B within recess  19 , respectively. In this way, the RF supply and return voltages from RF signal generator  178  are automatically applied to the electro-cauterizing electrodes embedded within the cannula assembly of the present invention.  
      As illustrated in  FIG. 1C , hand-holdable housing  2  is provided with a hinged cover  21 . Hinged cover  21  allows cannula cavity  20  to be opened and accessed so that cannula assembly  3  can be selectively installed in cannula cavity  20  and removed therefrom as desired or required. Cover panel  21  has a semi-circular cross-sectional geometry and is connected to the remaining portion of housing  2  by a conventional hinge means  25 . To secure cover panel  21  to the remainder of housing  2 , a releasable locking means  26  is provided at the interface of hinge cover  21  and housing  2 , as shown. Releasable locking means  26  can be realized in a variety of ways, including, for example, using a spring biased clamp element  27  which engages in a notch  28  formed in the external surface of the remaining housing portion, as illustrated in  FIG. 1C .  
      In general, there are numerous ways to effectuate reciprocation of inner cannula  4  within cannula cavity  20  and thus within stationary outer cannula  5 . Examples of possible reciprocation means  6  include, but are not limited to, gas or electrically driven motor(s). In the embodiments illustrated in  FIGS. 1A through 1C ,  FIGS. 4A through 6A ,  FIGS. 7 through 8 A,  FIGS. 6A through 6D , and  FIGS. 10 through 14 D, one or more gas driven piston-type motors are employed to realize the reciprocation means  6  within the liposuction instrument. In the embodiment illustrated in  FIGS. 9A through 9F , a rotary-type motor is used to realize reciprocation means  6  of the present invention.  
      As illustrated in  FIG. 1B , a piston-type motor  6  is mounted within a motor cavity  30  provided adjacent to cannula cavity  20  of housing  2 . Notably, this reciprocation means cavity  30  extends essentially parallel to cannula cavity  20  and along a substantial portion of the longitudinal dimension of hand-holdable housing as will become more apparent hereinafter. This unique spatial relationship between the cannula cavity and reciprocation means cavity within housing  20 , ensures optional cannula displacement relative to longitudinal dimensions of the hand-holdable housing.  
      In general, motor  6  comprises a chamber housing  31  having a gas inlet port  32  and an inner chamber generally indicated by reference numeral  33 . Slidably received within the inner chamber of housing  31  is a movable piston  34  having formed in the lower portion wall  35 , one or more gas outlet ports  36 . Mounted to the top portion of movable piston  34  is actuation element  37 , whose extension  13  projects through longitudinally disposed slot  38  formed in the bearing wall surface  22  of cannula cavity  20 . As shown in  FIG. 1B , actuation extension  13  passing through slot  38 , is received within notch  12  formed in inner cannula base  10  and operably associates inner cannula  3  with motor  6 .  
      As illustrated in  FIG. 1B , chamber housing  31  is fixedly disposed within motor cavity  30 . Motor cavity  30  is also provided with at least one port  39  for ventilating to the ambient environment, and gas is released from inner chamber  33  upon movable piston  34  reaching its maximum displacement or excursion. Movable piston  34  is biased in the direction of chamber housing  31  by way of a spring biasing element  40 . The compliance of spring biasing element  40  can be adjusted by moving the position of slidable wall  41  by rotating, for example, threaded element  42  passing through a portion  43  of housing  2 , as shown. With this arrangement, adjustment of wall  41 , closer to or farther from chamber housing  31 , results in decreasing or increasing, respectively, the compliance of spring biasing element  40 . This mechanism, in turn, provides a simple, yet reliable way in which to control the rate of reciprocation of movable piston  34 , and thus the rate of reciprocation of inner cannula  3  relative to housing  2 .  
      The manner of operation of piston-type motor  6  is described as follows. Gas, such as pressurized air or N 2  gas, is introduced under constant pressure to inlet port  32  of chamber housing  31 . As the gas fills up the volume enclosed by the interior walls of movable piston  34  and chamber  33 , inner chamber  33  begins to expand, forcing movable piston  34  upwardly against the biasing force of spring biasing element  40 . When movable piston  34  is displaced sufficiently enough from chamber housing  31  so that gas within expanding chamber  33  can be released through gas exit port  39  to the ambient atmosphere, piston  34  will be forced back downwardly into chamber housing  31 . The rate of the forced downward piston movement is inversely proportional to the compliance of spring biasing element  40 . Subsequently, chamber  33  will again fill up with gas, piston  34  will again be displaced and gas subsequently vented, whereupon reciprocating displacement of piston  34  will be repeated again in a cyclical manner. Since movable piston  34  is operably connected with inner cannula base  10  by way of actuation element  37 , this reciprocating movement of piston  34  results in reciprocating movement of inner cannula  3  within cannula cavity  20 . Further, this relative reciprocation between the inner cannula and the outer cannula results in periodic displacement of the effective aspiration apertures along the distal end portion of the cannula assembly.  
      As illustrated in  FIG. 1B , the amount of excursion that piston  3  is permitted to undergo before gas venting and subsequent downward piston movement occurs, is determined by the distance “d” defined between gas output port  32  and top wall surface  47  of chamber housing  31 . A typical cannula excursion distance of about four inches, for example, will necessitate that the parameter d, defined above, be also about four inches.  
      In  FIGS. 4A and 4B , a second embodiment of the liposuction device of the present invention is shown. Liposuction device  1 B has an alternative cannula assembly retention means while inhering all of the structural features of the first embodiment illustrated in  FIGS. 1A through 1C . In particular, liposuction device  1 B does not have a hingedly connected housing cover panel, and instead incorporates a snap-fit type cannula assembly retention mechanism. In accordance with this embodiment, actuation element  37 ′ has an extension which is essentially flush with elongated slot  38  formed in cavity wall  22 .  
      In  FIGS. 4A and 4B , an alternative embodiment of the electro-cauterizing cannula assembly hereof is shown. This cannula assembly is similar to the above-described cannula assembly in all respects except for the extension on actuation element  37 . In this alternative embodiment, the extension on actuation  37 ′ is provided with a spring biased ball bearing  48  that projects slightly beyond cannula cavity wall surface  22 . When inner cannula base  10 ′ is pushed into cannula cavity  20  in the vicinity of actuation element  37 ′, ball bearing  48  engages within indentation ring  49  circumferentially formed about inner cannula base  10 ′. Notably, spring biased ball bearing  48  functions as an engaging means for inner cannula base  10 ′.  
      As shown in  FIG. 4A , the engaging means for outer cannula base  17 ′ is also realized as a spring biased ball bearing  50  installed through cannula cavity wall  22 . Outer cannula base  5 ′ is provided with an annular flange  47  and indentation ring  49  circumferentially formed about outer cannula base  17 ′. As shown, annular flange  57  establishes surface to surface contact with peripheral surface  58  area of the housing when cannula base  5 ′ is pushed into cannula cavity  20 . In this position, ball bearing  50  engages within indentation ring  49  and a snap-fit engagement is established. This arrangement serves to retain both inner and outer cannulas  4 ′ and  4  and cannula cavity  20 ′, in a releasable manner, as actuation element  37 ′ is caused to reciprocate periodically. The outer cannula is simply removed from cannula cavity  20  by quickly pulling on outer cannula tube  5  with a modest degree of force, to overcome the bias force of engaged ball bearing  50 . Similarly, the inner cannula is simply removed by quickly pulling on inner cannula tube  4 ′ to overcome bias force of engaged ball bearing  50 . Advantageously, this cannula assembly retention mechanism can also provide a safety release feature, in that if inner cannula  4 ′, for example, becomes snagged during an operation, it will disengage from the reciprocation means  6  if a proper spring biasing force is selected for ball bearing  50 .  
       FIGS. 7A, 7B  and  8  also show an electro-cauterizing cannula assembly according to the present invention which is adapted for use with liposuction instruments having cannula retention capabilities of the snap-in type described above. Notably, the elements which correspond to inner and outer cannulas illustrated in FIGS.  2 A through  3 B 1 , are indicated by similar reference numbers.  
      In the embodiment featured in  FIGS. 7A and 7B , inner cannula base  10 ″ has a deeply formed spherical indentation  52  which is adapted to receive ball bearing  48  mounted in the extension of in actuation element  37 . To facilitate guiding ball bearing  48  into spherical indentation  52 , a longitudinally extending groove  53  is formed in inner cannula base  10 ″. Also, as shown, widened recess portions  53 A and  53 B are provided at opposite ends of groove  53  to facilitate initial insertion of ball bearing  48  in groove  53 . When inner cannula base  10 ″ is slid into cannula cavity  20 , ball bearing  48  snaps into indentation  52  to establish a locked position. Biased ball bearing  48  engaged in spherical indentation  52  serves to retain inner cannula  5  within cannula cavity  20 , while facilitating reciprocation of inner cannula  5  when actuation element  37 ′ is caused to reciprocate.  
      Similar to the snap-fit inner cannula retention mechanism illustrated in  FIGS. 7A and 7B ,  FIG. 8  shows outer cannula base  17 ″ having a longitudinally extending groove  55 . Also, as shown, widened recess portions  55 A and  55 B are formed at opposite ends of groove  55  to facilitate insertion of ball bearing  50  into spherical indentation  56 . When outer cannula base  17 ″ is slid into cannula cavity  20 , ball bearing  50  snaps into spherical indentation  56  to establish a locked position. When this occurs, annular flange  57  will engage with outer peripheral surface  58 , about circular access opening leading into cannula cavity, shown in  FIG. 4A . Upon such engagement, outer cannula  5  is rendered stationary relative to hand-holdable housing  2 . As with inner cannula  4 , the outer cannula is simply removed from cannula cavity  20  by pulling on outer cannula tube  5  with a modest degree of force to overcome the bias force of engaged ball bearing  50 .  
      In order to selectively adjust the amount of cannula excursion permitted during a liposuction operation, piston-type motor  6  can be modified, as shown in  FIG. 5 , to produce a third embodiment of the liposuction device of the present invention. As illustrated in  FIG. 5 , the basic structure of liposuction device  1 C is similar to that shown in  FIGS. 1A through 1C , except that a user-adjustable intermediate housing wall  88  is disposed between the inner walls  31 A of chamber housing  31  and the outer walls  34 A of movable piston  34 . Intermediate housing wall  87  is operably associated with an excursion selection means realized as a slidable member  88  fixedly attached to the upper portion of intermediate housing wall  59 . Preferably, slidable member  88  extends through a slot  89  formed in the wall of housing  2  and can be slid, for example, by movement of the surgeon&#39;s thumb. The function of intermediate housing wall  87  is to effectively raise the height of the chamber housing wall, and thus selectively increase distance d, defined, for example, as the distance between gas outlet port  32  in piston  34  and upper portion  63  of the chamber housing wall. In this way, movable piston  34  must undergo a larger displacement before compressed gas will be released and piston  34  permitted to be forced downwardly under the biasing force of biasing spring element  40 .  
      As illustrated in the embodiment shown in  FIG. 5 , it is also possible to control the rate of reciprocation of the inner cannula by controlling the rate of gas flow entering chamber  33  of piston-type motor  6 . This can be achieved using a conventional gas flow regulation device  78  inserted between source of gas “S” and inlet port  32  of chamber housing  31 . As shown, tubing sections  79 A and  79 B are used to achieve fluid communication between these elements. Typically, cannula reciprocation rates will be in the range of  30  to  90  reciprocation cycles per minute, and the corresponding gas flow rates will depend on parameters including, for example, the compliance of biasing spring  40 , the volumes of movable piston  34  and chamber housing  31 , the cross-sectional diameter of gas inlet port  32 , and the cross-sectional diameter of gas outlet ports  36  in the piston.  
      Referring to  FIGS. 6A through 6D , there is shown another embodiment of the liposuction device of the present invention. In liposuction device  1 F, the housing and cannula assembly are generally similar to those of the previously described embodiments, with the exception of several differences, which will be described below.  
      As illustrated in  FIG. 6A , a pair of piston-type motors  6 A and  6 B of the type generally indicated in  FIGS. 1A through 1C  and  5 , are fixedly installed within respective motor cavities  30 A and  30 B of housing  2 . Each piston-type motor  6 A and  6 B has a respective chamber housing and movable piston, indicated by  31 A and  31 B, and  34 A and  34 B, respectively. Actuation elements  37 A and  37 B are fixedly connected to respective pistons  34 A and  34 B and project through respective elongated slots  38 A and  38 B formed in cannula cavity wall  22 ; this is achieved in a manner similar to that described in connection with the embodiments shown in  FIGS. 1A through 1C ,  4 A,  4 B and  5 . While not shown in  FIG. 6A , preferably a rod or bar is fixedly attached between actuation elements  37 A and  37 B in order to maintain them a fixed distance apart, and yet provide an operable connection between the inner cannula  4 ′ and actuation elements  37 A and  37 B in the manner described below. As shown in  FIG. 6B , this embodiment includes hinged cover panel  21  in a manner similar to that described in the embodiments of  FIGS. 1A, 1C ,  5 ,  6 A and  8 A.  
      As illustrated in  FIG. 6A , inner cannula base  10 ′″ has first and second receiving slots or notches  12 A and  12 B, into which extensions  13 A and  13 B of respective actuation elements  37 A and  37 B are received. Such operable connections between movable pistons  6 A and  6 B and inner cannula base  10 ′″ enables inner cannula  4 ′ to reciprocate relative to housing  2  when actuation elements  37 A and  37 B are caused to reciprocate relative to respective gas driven motors  6 A and  6 B.  
      In order to control the filling and venting of chambers  33 A and  33 B of the first and second piston motors, to effectuate cyclical reciprocating motion of actuation elements  37 A and  37 B and thus inner cannula  4 ′, a mechanically-operated gas flow control device  90  is provided. As shown in  FIG. 6A , gas flow control device  90  is employed in operable association with an external source of pressurized gas (not shown), gas inlet ports  32 A and  32 B, and movable pistons  34 A and  34 B.  
      As illustrated in greater detail in  FIGS. 6C and 6D , gas flow control device  90  comprises a shuttle valve housing or casing  91 , having first and second shuttle chambers  92 A and  92 B. These shuttle chambers are separated by a shuttle valve member  93 , which is fixedly attached to a slidable shaft  94 . As illustrated, shuttle valve member  93  is slidable between two positions or states “A” and “B”. In order to achieve this shaft  94  extends through bores  95 A and  95 B formed in shuttle chamber end walls  91 A and  91 B respectively, in which seals  96 A and  96 B are installed in a conventional manner. When the shuttle valve  93  is centrally disposed in casing  91  between states A and B, shaft ends  94 A and  94 B protrude equally beyond respective bores  95 A and  95 B.  
      Adjacent one end of the cylindrical shuttle chamber side wall  98 , a first gas exit port  89 A is formed, whereas adjacent the other end of wall  98 , a second gas exit port  98 B is formed, as shown. At about intermediate the end walls, a gas inlet port  100  is formed in shuttle chamber side wall  98 . A pair of annulus-shaped shuttle valve stops  101 A and  101 B are formed at opposite end portions of the interior surface of cylindrical wall  98 . These stops  10 A and  101 B serve to limit sliding movement of shuttle valve  93  when shaft  94  is displaced in one of two possible axial directions by actuation elements  37 A and  37 B, respectively, as shown in  FIG. 6A . As will be discussed in greater detail hereinafter, it is these actuation elements  37 A and  37 B, which displace shaft  94  and thus shuttle valve  93  between one of two states, as movable pistons  34 A and  34 B are caused to reciprocate. Preferably, at least a portion of shuttle valve  93  is formed of a ferromagnetic material so that ferrous end walls  102 A and  102 B will attract ferromagnetic shuttle valve  93  and pull it against one of stops  101 A and  101 B and into gas flow state A or B, i.e., when shuttle valve  93  is brought into proximity therewith upon displacement of shaft  94  by one of actuation elements  37 A and  37 B. Peripheral side surfaces of shuttle valve  93  are provided with seals  103  to prevent gas leakage between shuttle chambers  92 A and  92 B.  
      As illustrated in  FIG. 6A , first gas exit port  99 A of device  90  is in fluid communication with second chamber housing  31 B by gas channel  104 , whereas second gas exit port  99 B is in fluid communication with first chamber housing  31 A by gas channel  105 . In the illustrated embodiment, gas inlet aperture  106  is formed through housing  2  and permits gas channel  107  to establish fluid communication between gas inlet port  100  and the external source of pressurized gas. Notably, chamber housings  31 A and  31 B, shuttle valve housing  91 , gas channels  104 ,  105  and  107  can be realized as discrete elements, as shown, or alternatively as integrally formed elements which are part of the interior of the hand-holdable housing itself.  
      The principal function of gas flow control device  90  is to control the flow of gas to pistons  34 A and  34 B so that only one of the gas pistons is actively driven at a time, while the other is passively driven. The manner of operation of gas flow control device  90  in cooperation with the periodic displacement of pistons  34 A and  34 B, will now be described.  
      Owing to the fact that shuttle valve  93  is magnetically biased to be in essentially one of two possible positions, or gas flow states, gas will initially be caused to flow into one of piston-chamber housings  31 A or  31 B, and cause its respective piston and actuation element to move away (i.e., protract) from its respective chamber housing. Only along a small portion of the piston excursion will shuttle valve shaft  94  and thus shuttle valve  93 , be displaced within shuttle valve housing  91  as the actively driven piston is displaced upon buildup of pressurized gas within its respective chamber.  
      To illustrate this cyclical process, it will be assumed that gas flow control valve  90  is initially in state A, as shown in  FIG. 6A . Here, piston  34 A has reached its maximal displacement and pressurized gas within chamber  33 A has been substantially vented through gas outlet port  26 A and through ports  39 A and  39 B. In this position (state A), shuttle valve  90  is magnetically biased against stops  101 B so that gas is caused to flow from the external gas source (not shown), through first shuttle chamber  92 A and into second chamber housing  33 B. With shuttle valve  93  in this state, gas pressure is allowed to build up in chamber  33 B, displacing piston  34 B and actuation element  37 B to protract from second chamber housing  31 B. Therewhile, inner cannula base  10 ′″ is caused to undergo an outwardly directed excursion within cannula cavity  20 , commensurate with the active displacement of piston  34 B. During piston excursion (i.e., travel) defined over length L 1 , shuttle valve  93  remains in stage A against stop  101 B. Then over piston excursion L 2 , actuation element  37 B contacts shaft end  94 B and displaces shuttle valve  93  away from stop  101 B to about mid-position in shuttle housing  91 , approximately over input port  100 , at which point, magnetic shuttle valve  93  is pulled toward ferrous plate  102 A into state B and against stop  101 A, as shown in  FIG. 6A  with phantom lines. At this phase in the cycle, piston  34 A is fully retracted within chamber housing  31 A, while piston  34 B is fully protracted from chamber housing  31 B and displaced a distance L 3  from the upper portion thereof (i.e., L 3 =L 1 +L 2 ). In State B, gas flow control device  90  directs the flow of pressurized gas from the external source, along channel  107 , through second shuttle chamber  92 B and along channel  105  and into piston chamber housing  31 A.  
      Magnetically biased shuttle valve  93  remains in state B as chamber housing  31 A fills with pressurized gas, expanding the chamber  33 A and actively displacing piston  34 A away from chamber housing  31 A, while causing piston  34 B to passively retract back into its chamber housing  31 B. All the while, inner cannula base  10 ′″, being operably associated with actuation elements  37 A and  37 B, undergoes a commensurate amount of inwardly directed excursion within cannula cavity  20 . When piston  34 B is displaced an amount of distance L 4 , actuation element  37 A contacts shaft end  94 A and displaces shuttle valve  93  a small distance L 5 , at which point, magnetic shuttle valve  93  is pulled towards ferrous plate  102 B, back into state A and against stop  100 B. At this phase in the cycle, piston  34 B is fully retracted within chamber housing  31  while piston  34 A is fully protracted within chamber housing  31 A and displaced at a distance L 6  from the upper portion thereof (i.e., L 6 =L 4 +L 5 ). In state A, gas flow control device  90  directs the flow of pressurized gas from the external source, along channel  107 , through first shuttle chamber  92 A, along channel  104  and into piston chamber housing  31 B.  
      Magnetically biased shuttle valve  93  remains in state A as chamber housing  91 B fills with pressurized gas, expanding chamber  3 B and actively displacing piston  34 B away from chamber housing  31 B, while causing piston  34 A to passively retract back into its piston chamber housing  31 A. All the while, inner cannula base  10 ′″, being operably associated with actuation elements  37 A and  37 B, undergoes once again a commensurate amount of outwardly directed excursion within cannula cavity  20 . With a preselected gas pressure and flow rate set at gas inlet port  100  of device  90 , the above-described process of gas filling, venting and flow control occurs automatically at a corresponding rate, resulting in periodic reciprocation of inner cannula  10 ′″ relative to hand-holdable housing  2 . In turn, this periodic reciprocation of inner cannula  4 ′ results in periodic displacement of the general location of aspiration occurring along the length of the cannula assembly.  
      Referring to  FIGS. 9A through 9F , there is illustrated yet a seventh embodiment of the liposuction device of the present invention. In general, liposuction device  1 G has a pistol-shaped housing  110  which comprises a barrel portion  111  and a detachable handle portion  112 . Instead of using a reciprocating piston motor to translate inner cannula  4 ′ relative to housing  100 , this embodiment utilizes a rotary-type motor  113 . In operative association with a cam mechanism, generally indicated by reference numeral  114 , rotary-type motor  113  causes actuation element  115  to cyclically slide back and forth and cause inner cannula  4 ′ to periodically reciprocate relative to barrel portion  111  of the pistol-shaping housing.  
      As illustrated in  FIGS. 9B through 9D , barrel portion  111  of the housing comprises a cannula cavity  116  adapted for slidably receiving cylindrically-shaped base  17  of inner cannula  4 ′, in a manner described hereinabove. Cannula cavity  116  is also provided with a longitudinally extending access opening, over which a hingedly connected cover panel  117  is provided. As illustrated in  FIG. 9E , cover panel  117  facilitates insertion of the cannula assembly into, and removal of the cannula assembly from, cannula cavity  116  in a manner similar to that described in connection with liposuction instrument  1 A of  FIGS. 1A through 1C , in particular. As illustrated in  FIG. 9C  in greater detail, inner cannula base  10  is adapted to be received within cannula cavity  116  and outer cannula base flange  19  releasably received with annular recess  118  formed in cannula cavity wall  22 .  
      To install inner cannula  4 ′ into cannula cavity  116 , semi-flexible transparent tubing  15  is connected to inner cannula outlet port  11 . Then cover panel  117  is opened and tubing  15  is fed out through rear port  119  of the barrel portion, as illustrated in  FIGS. 9C and 9F . Inner cannula base  10  is then slid into cavity  116  with an extensional portion of actuation element  115  received in notch  12 . Then outer cannula  5 ′ is slid over the distal end of inner cannula  4 ′ until outer cannula base  17  is received within annular recess  118 . Thereafter, as shown in  FIG. 9E , cover panel  117  is snapped closed using, for example, a spring biased locking device  120  of the type previously described above. Removal of inner and outer cannulas simply involves a reversal of the above procedure.  
      Alternatively, using spring biased actuation elements and inner and outer cannulas of the type shown in  FIGS. 4A and 4B , barrel portion  111  can be realized without necessity of hinged cover panel  117 . In such an alternative embodiment, the inner and outer cannulas can be snap-fitted into and pulled out of cannula cavity  116  in a manner similar to that described hereinabove.  
      As illustrated in  FIGS. 9B through 9F , barrel portion  111  houses cam mechanism  114  which is operably associated with (i) rotary motor  113  contained within the handle portion, and (ii) actuation element  115  which slidably passes through a longitudinal slot  121  formed within the upper wall of cannula cavity  116 . As in the other previously described embodiments, actuation element  115  includes extension  115 A that passes through elongated slot  121  and is received within notch  12  formed in inner cannula base  10 . In addition, cam mechanism  114  of the illustrated embodiment inherently embodies gear reduction. In this way, a high angular shaft velocity of rotary motor  113 , can be efficiently transformed into reciprocational strokes of the cannula, occurring at a substantially lower rate. With such an arrangement, as rotary motor  113  is caused to rotate under either gas pressure or electrical power, actuation element  115  is caused to reciprocate within elongated slot  121  by way of cam mechanism  114 , and thereby cause inner cannula  4 ′ to periodically reciprocate relative to housing  110 . This motion results in periodic displacement of the general location of aspiration occurring along the length of the cannula assembly.  
      As illustrated in  FIGS. 9B and 9C , cam mechanism  114  of the preferred embodiment comprises a drive wheel  122  having a first predetermined number of gear teeth  123  disposed thereabout. Drive wheel  122  is rotatably mounted to a shaft  124  mounted through and opening in the top panel of an accommodating section  125  of the barrel portion. Cam mechanism  114  also includes a connective element  126  having first and second ends  126 A and  126 B, respectively. First end  126 A of the connective element in pivotally attached to the drive wheel  122  at a point posed away from the axial center  124 , whereas second end  126 B is pivotally connected to actuation element  115  as shown. In order to adjust the distance away from the axis of rotation  124  at which the first end of the connective element is pivotally attached, a radially formed slot  127  is formed in drive wheel  122 . A plurality of widened circular apertures  128  is disposed along radial slot  127 , as shown in  FIGS. 9B and 9D . In this way, a spring-loaded cylindrical pin  129  passing through the first end of connective element  126 , can be selectively locked into one of apertures  128  by pulling upwardly upon pin  129  and setting its cylindrical base  129 A into the desired aperture  128 . In  FIG. 9D , pin  129  is shown to further include pin head  129 B, a hollow bore  129 B, and an axle  129 D having heads  129 E and  129 F. As shown, a spring  129 G is enclosed within bore  129 C, about axle  129 D and between head  129 F and an inner flange  129 H. By selectively locking the first end  126 A of connective element  126  into a particular circular notch  128  using spring loaded pin  129 , the distance of the first end of the connective element from axial center  124  can be set, and thus the amount of inner cannula excursion (and effective aspiration aperture displacement) thereby selected. To permit access to spring-loaded pin  129 , the top panel of accommodating portion  125  of the housing is provided with hinged door  132  that can be opened and snapped closed as desired.  
      As illustrated in  FIGS. 9B and 9C , handle portion  112  of the housing encloses a substantial portion of rotary motor  113  whose shaft  133  projects beyond the handle portion and bears a gear wheel  134 . As shown, gear wheel  134  has a second predetermined number of gear teeth  134 A disposed circumferentially thereabout, which mesh with drive wheel teeth  123 . Notably, to permit the rear portion  119  of cannula cavity  116  to extend all the way towards the rear of the barrel portion for passage and exit of aspiration hose  15 , shaft  133  of the motor is mounted off center of handle portion  113 , as shown in  FIGS. 9C and 9F .  
      Rotary motor  113  is preferably an electric motor whose shaft speed is controllable by the voltage applied to its terminals. Such speed control can be realized by a conventional speed control circuit  135  connected between motor  113  and a conventional 110-115 volt, 50-60 Hertz power supply. As illustrated in  FIG. 9C , conventional electrical cord  136  and on/off power switch  150  can be used to connect control circuit  135  and the power supply. Control over the output voltage produced from speed control circuit  115  and provided to electrical motor  113 , can be adjusted, for example, by changing the resistance of a potentiometer  137 , which is operably connected to the speed control circuit. As shown in  FIG. 6C  in particular, this potentiometer  137  can be embodied within a trigger mechanism  138 , which is connected, for example, to handle portion  112  of the housing  110 . By pulling trigger  138 , the speed of rotary motor  113  can be controlled, and consequently, so too the rate of reciprocation of inner cannula  4 ′ relative to outer cannula  5 ′, and thus the rate of displacement of the effective aspiration apertures.  
      To connect handle portion  112  to barrel portion  111  and permit disconnection therebetween for cleaning, sterilization and general service, handle portion  112  is provided with flange  140  and thumb operable spring element  141 . Barrel portion  111 , on the other hand, is provided with slot  142 , catch  143 , and cavity  144 . To connect handle portion  112  to barrel portion  111 , shaft  133  is vertically passed through channels  144  and  145  until gear  134  is slightly below the plane of drive wheel  122 . Then, spring element  141  is inserted within cavity  144  while flange  140  is guided into slot  142 . By pushing the rear portion of handle  112  in the longitudinal direction of cannula cavity  116 , spring element  141  will snap over and clasp catch  143  as shown in  FIG. 12C . In this configuration, handle portion  112  is secured to barrel portion  111  and gear teeth  123  will mesh with drive wheel teeth  134 A. To disconnect handle portion  112  from barrel portion  11 , the surgeon&#39;s thumb simply depresses spring-element  141  downwardly and then, by moving handle portion  112  slightly rearwardly, then downwardly, flange  140  is dislodged from slot  142  and motor shaft  133  can be withdrawn from channels  144  and  145 . In this disassembled state, handle portion  110  and barrel portion  112  can be individually cleaned and sterilized using conventional procedures known in the state of surgical instrument art.  
      Liposuction device  1 G described above employs an electrical rotary motor to effectuate reciprocation of inner cannula  4 ′ relative to housing  110 . However, in an alternative embodiment, it is possible to effect reciprocation of the outer cannula while the inner cannula is stationary with respect to the housing, as shown in  FIGS. 6A through 7 . Also, it is possible to employ a conventional gas driven rotary motor in lieu of electric rotary motor  113 . In such an embodiment, trigger  138  can be operatively associated with a gas flow control valve. Thus, by controlling the rate of gas flow to the gas rotary motor upon actuation of trigger  138 , the angular velocity of shaft  133  can be controlled and thus the rate of reciprocation of inner cannula  4 ′ relative to housing  110 .  
      Having described various illustrated embodiments, it is appropriate at this juncture to describe the method of the present invention using, for purposes of illustration only, the liposuction instrument  1 C illustrated in  FIG. 5 .  
      In general, the surgeon prepares in a conventional manner, the area of skin below which liposuction is to be performed. Typically, this entails marking various zones where radial displacement of the aspiration apertures is to occur. Liposuction instrument  1 C of the present invention is assembled as described above so that aspiration apertures  8 A′,  8 B′ and  8 C′ of cannula assembly  3 ′ are in communication with a vacuum source (not shown). A small incision is then made in the patient&#39;s skin in a conventional manner, and the distal portion of the cannula assembly is inserted into a premarked radial zone. As pressurized gas is provided to piston motor  6 , inner cannula  10  will automatically reciprocate causing the general location of the suction apertures to be automatically displaced along each tunnel of fatty tissue. During the operation of the instrument, the surgeon&#39;s hand holding the liposuction instrument is maintained essentially stationary with respect to the patient. Fatty tissue is aspirated through the periodically displaced aspiration apertures, and transferred into a reservoir tank operably associated with the vacuum source.  
      As deemed necessary, the surgeon can selectively increase the rate of aspiration aperture travel along the distal end of the cannula assembly. This can be achieved by a foot-operated gas flow control device  78 , which controls the rate of gas flow to piston motor  6 . Also, the amount of inner cannula excursion (i.e., aspiration aperture travel) can also be selected by adjusting the compliance of spring  40  through rotation of threaded element  42 .  
      In the illustrative embodiments described hereinabove, the outer cannula has been made from an electrically non-conductive material (i.e., achieving electrical isolation between the cauterizing electrodes supported on the outer cannula, and electrically conductive inner cannula). The inner cannula ha been made from stainless steel, offering the advantage of being easily cleaned and sterilizable. The plastic outer cannula offers the advantage of electrical insulation, low manufacturing cost and disposability. Preferably, when making the outer cannula from a suitable plastic material, injection molding processes can be used.  
      In  FIG. 10 , an alternative embodiment of the liposuction instrument of  FIG. 9  is shown. While this embodiment of liposuction instrument hereof  180  is similar to the embodiment shown in  FIG. 9 , there are a number of differences. For example, an actuator  181  magnetically-coupled to an air powered cylinder  182  is used to reciprocate the base portion  10  of the inner cannula of its electro-cauterizing cannula assembly. The magnetically-coupled air powered cylinder and actuator subassembly ( 182 ,  181 ) can be realized as Model No. MG 038 commercially available from Tol-O-Matic, Inc. of Hamel, Minn. As shown in  FIG. 10 , the ends of the air powered cylinder  182  are supported by an external guide and support system comprises brackets  183 A and  183 B, which are integrated with interior portions of the hand-holdable housing. The actuator block  181 , which is mounted about the cylindrical shaft of the cylinder  182 , is reciprocated between the support brackets  183 A and  183 B in response to pressurized air (gas) flowing into its first air input/output port  184 A, and then the second air input/output port  184 B, repeatedly in an alternating manner, causing the actuator  181  to reciprocate along the cylinder  182 . Such pressurized air streams are provided by an air-flow control device  185 .  
      As shown in  FIG. 10A , the air flow control device  185  has one air supply port  185 A, first and second air output/return ports  185 B and  185 C, and first and second air exhaust ports  185 D and  185 E. Air supply port  185 A is supplied with pressurized air through tubing  185 A 1  connected to flow rate control unit  219  which is controlled by electrical signals produced by trigger  138  when pulled to a particular degree of angular function of deflection. The control unit  219  is to control the flow of air from supply tubing section  219 A connected to an external source of pressurized air. The first and second air output/return ports  185 B and  185 C, are arranged in fluid communication with the first and second air input/output ports  184 A and  184 B of the cylinder  182 , respectively, by way of air tubing sections  186  and  187 .  
      As shown in  FIG. 10A , air-flow control device  185  has an air flow control shaft  188  with air flow directing surfaces  188 A. Air flow control shaft  188  is slidably supported within the housing of the device. The function of the flow control shaft is to commute air flow between its various ports described above in response to the position of the actuator  181  along the cylinder  182  during device operation. In order to achieve such functions, the air-flow control shaft  188  of the illustrative embodiment is mechanically coupled to an actuator stroke control rod  189  by way of a mechanical linkage  190 . Linkage  190  is supported by brackets  191 A,  191 B and  191 C and secured to the interior of the hand-holdable housing. Along the actuator stroke control rod  189 , a pair of actuator stops  192 A and  192 B are disposed. In the illustrative embodiment, stops  192 A and  192 B are disposed. In the illustrative embodiment, stops  192 A and  192 B are realized as slidable rods which are adapted to lock into different detented positions along the stroke control rod  189  when the surgeon presses the top thereof (located outside of the housing) downwardly and then in the direction of the adjustment, releasing the control stop at its desired location. In some embodiments, it may be desirable to fix one of the control stops while allowing the other control stop to be adjustable along a selected portion of the length of the stroke control road  189 . In alternative embodiments, actuator stroke control can be realized using other types of adjustment mechanisms including, for example, an externally accessible adjustment screw mechanism, in which adjustment (rotation) of a single knob or thumbOwheel enables the surgeon to set the stroke length of the inner cannula and thus the aspiration aperture thereof; electronic control mechanisms, in which actuation of an electronic or electrical device, such as foot pad or electrical switch enables the surgeon to translate the position of one or both of the stroke control stops by electromechanical means (including linear motors, geared rotary motors and the like).  
      As shown in  FIG. 10A , the air flow control shaft  188  has two primary positions; a first position, in which pressurized air from the air supply port  185 A is directed to flow through the second air output/return port  188 C of the air flow control device, along tubing  187  and into the second input/output port  184 B of the cylinder  182 , while the second input/outlet port  184 B of the cylinder is in communication with the first exhaust port  185 D of the air flow control device  185  causing inner cannula to project away from the housing; and a second position, in which pressurized air from the air supply port  185 A is directed to flow through the first air output/return port  188 B of the air flow control device, along tubing  186  and into the first input/output port  184 A of the cylinder, while the second input/outlet port  184 B of the cylinder is in communication with the second exhaust port  185 E of the air flow control device  185 , causing the inner cannula to retract inwards towards the housing. By virtue of this arrangement, the actuator  181  is automatically driven back and forth between stroke control stops  192 A and  192 B along the cylinder stroke rod in response to pressurized air flow into the air flow control device  185 . When the electro-cauterizing cannula assembly of  FIG. 11A  is installed within the cannula cavity of the liposuction device, as described hereinabove, the inner cannula  4  will be caused to reciprocate relative to the outer cannula  5 . In the illustrative embodiment, the length of the excursion of the inner cannula  4  is determined by the physical spacing between mechanical stops  192 A and  192 B. By varying the spacing of these stops along the stroke control rod  182 , the maximum excursion of the inner cannula relative to the stationary outer cannula can be simply and easily set and reset as necessary by the surgeon.  
      In  FIG. 11A , an electro-cauterizing cannula assembly  3 ″ is shown for use with the liposuction instrument of  FIG. 10 . In this illustrative embodiment, both the inner and outer cannulas are made of an electrically non-conductive material such as sterilizable plastic. In the embodiment of  FIG. 10 , hand-holdable housing is preferably made from an electrically non-conductive material. Electrically conductive electrodes  195 A,  195 B,  195 C an  195 D are inserted within the inner aspiration apertures  8 A,  8 B,  8 C and  8 D, and electrical wiring  196  runs to the inner cannula base portion  10 , wherein an electrical contact pad  197  is embedded. Electrically conductive electrodes  160 A,  160 B,  160 C and  160 D are also inserted within the outer aspiration apertures  16 A,  16 B,  16 C and  16 D, and electrical wiring  168  runs to the outer cannula base portion  19 , wherein an electrical contact pad  166 B is embedded. An electrical contact pad  176 B is also embedded within the base portion recess within the hand-holdable housing.  
      As shown in  FIGS. 10 and 11 , an electrical contact rail  198  is embedded within the side wall surface of the cannula cavity so that electrical contact pad  197  on base portion  10  of the inner cannula establishes electrical contact therewith to apply RF (supply/return) power signals to the electrodes in the inner cannula during liposuction operations. In such circumstances, two sets of electrical connections occur. Firstly, the base portion  10  of the inner cannula is securely engaged by the actuator block  181  (snap-fitting or other suitable means) and the electrical contact pad  197  contact with the electrical rail  198  embedded within the inner side wall surface of the cannula cavity. Secondly, the base portion  19  of the outer cannula is received within the base portion recess of the hand-holdable housing and the electrical contact pad (i.e., RF power supply terminal)  176 B embedded therewithin establishes contact with the electrical contact  166 B embedded within the base portion of the outer cannula. By virtue of these electrical connections, RF supply potentials are applied to the electrode portions of the inner cannula, while RF return potentials are applied to the electrode portions of the outer cannula, whereby electro-cauterization occurs.  
      In  FIG. 13A through 13D , an alternative electro-cauterizing cannula assembly  3 ′″ is shown for use with the liposuction instrument shown in  FIGS. 10 and 10 A, and readily adaptable for use with other liposuction instruments of the present invention. In this particular illustrative embodiment, both the inner and outer cannulas are made of an electrically conductive material. The hand-holdable housing is made from an electrically non-conductive material (e.g. plastic). Between these electrically non-conductive cannulas  4  and  5  means are provided for maintaining electrical isolation between the electrically conductive carrier and outer cannula which, during electro-cauterization, are maintained at an electrical potential difference (i.e., voltage) of 800 volts or more. In general, a variety of different techniques can be employed for carrying out this function. For example, a thin coating of Teflon® material  200  can be applied to the outer surface of the inner cannula, and/or to the inner surface of the outer cannula. Alternatively, a series of electrically-insulating spacer/washers made from Teflon® ceramic, or like material can be mounted within circumferentially extending grooves formed periodically about the inner cannula to maintain sufficient spacing and thus electrical insulation between the inner and outer cannulas. Preferably, the spacing between each pair of insulating spacers is smaller than the length of the bore  18  formed in the electrically conductive base portion of the outer cannula, as illustrated in  FIG. 13A .  
      As shown in  FIG. 11G , electrical contact rail (i.e. RF power supply terminal)  198  embedded within the cannula cavity establishes electrical contact with the base portion  10  of the inner cannula when the cannula assembly is installed in the housing of the device. Also, electrical contact pad  176 B embedded within the recess portion of the housing establishes electrical contact with the base portion of the outer cannula when the cannula assembly is installed within the hand-holdable housing. In the assembled state, two sets of electrical connections occur. First, the electrically conductive base portion of the inner cannula is engaged by the electrical contact rail  198 . Secondly, the base portion of the outer cannula is received within the base portion recess and the base portion of the outer cannula establishes contact with the electrical contact  176 B embedded within the recess portion. By virtue of these electrical connections, RF supply potentials are applied to the inner cannula, while RF return potentials are applied to the outer cannula. The potential difference(s) between these surfaces about the aspiration apertures enable electro-cauterization of tissue as it is being aspirated through the aspiration aperture moving along the cannula assembly.  
      In another illustrative embodiment of the present invention, the inner cannula  4  is made of an electrically non-conductive material such as plastic. The outer cannula is made of electrically conductive material (e.g., stainless steel). The hand-holdable housing is made from an electrically non-conductive material (e.g., plastic). Electrically conductive electrodes are inserted within the inner aspiration apertures thereof, and electrical wiring run to the inner cannula base portion, wherein an electrical contact rail is also embedded.  
      As shown in  FIG. 14G , an electrical contact rail  213 A is also embedded within the side wall of the cannula cavity. An electrical contact pad embedded within the recess of the plastic hand-holdable housing establishes electrical contact with the base portion of the electrically conductive outer cannula. Thus, when the cannula assembly is installed within the hand-holdable housing, two sets of electrical connections occur. First, the base portion of the inner cannula is engaged by the actuation means and the electrical contact pad therewithin establish contact with the electrical contacts embedded within the base portion of the inner cannula. Secondly, the base portion of the outer cannula is received within the base portion recess and the electrical contact pads embedded therewithin establishes contact with the electrical contact embedded within the base portion of the outer cannula. By virtue of these electrical connections, RF supply potentials are applied to the electrode portions of the inner cannula, while RF return potentials are applied to the electrode portions of the outer cannula.  
      In yet other alternative embodiments of the present invention, hemostasis can be carried out in the powered liposuction instruments hereof by producing ultrasonic energy (having a frequency of about 50 kilohertz) and delivering the same to the aspiration aperture regions of the cannula assembly during liposuction procedures. Such ultrasonic energy will cause protein coagulation of aspirated tissue in the regions of the aspiration apertures. When the frequency of the ultrasonic energy is reduced to about 20-25 kilohertz, liquefaction or lipolysis of the aspirated tissue will occur. Such modes of operation can be added to any of the electro-cauterizing liposuction instruments of the present invention, or to liposuction instruments with electro-cauterizing capabilities.  
      In  FIGS. 14 through 14 C, a preferred embodiment of the ultrasonic cauterizing liposuction instruments of the present invention is shown. In general, the embodiment shown in  FIGS. 14 through 14 C is similar to the liposuction instrument of  FIG. 10 , except that it includes several additional means which enable it to effect protein coagulation (and thus hemostasis) during liposuction using ultrasonic energy having a frequency of about 50 kilohertz and sufficient power. As shown, a set of piezo-electric crystals  210  are embedded about the lumen of the inner cannula and encased within the base portion of the inner cannula made of plastic.  
      As shown in  FIG. 1 , an electrical signal generator  216  external to the liposuction device is provided for supplying electrical drive signals to terminals  214  via control circuit  215  when it is enabled by manual actuation of trigger  138 . The electrical signal generator  216  should be capable of producing electrical signals having a frequency in the range of about 15 to 60 KHz, at a sufficient power level. Any commercially available signal generator, used in medical applications, can be used to realize this system component. The electrical signals produced from generator  216  are applied to the terminals of the piezo-electric transducers embedded within the electrically non-conductive base portion of the inner cannula.  
      When the generator  216  is switched to produce signals in range centered about 20 KHz, these signals are delivered to the array of piezo-electric transducers embedded within the base portion of the inner cannula. These drive signals cause the piezo-electric transducers to produce ultrasonic signals in substantially the same frequency range to propagate along the surface of the inner cannula and out the inner and outer aspiration apertures, enabling lipolysis or liquefaction of aspirated fat tissue.  
      When the generator is switched to produce signals in a range centered about 50 KHz, these signals are delivered to the array of piezo-electric transducers embedded within the base portion of the inner cannula. These drive signals cause the piezo-electric transducers to produce ultrasonic signals in substantially the same frequency range to establish standing waves within the inner cannula, which propagate out the apertures of inner and outer cannula, enabling coagulation of protein molecules within aspirated tissue, thus achieve hemostasis.  
      While carrying out lipolysis using ultrasonic energy producing means within the liposuction device hereof, the surgeon may also desire to conduct hemostasis by coagulating protein molecules within tissue being aspirated. As shown in  FIG. 14 , by pulling trigger  138 , control circuit  217  automatically commutes RF supply and return signals from the RF signal supply unit  175  to power supply terminals  218  which, in turn, are connected to contact pads  176 A and  176 B embedded within recess  17 A, supporting the base portion of the outer cannula with respect to the hand-holdable housing.  
      As shown in  FIGS. 10 and 14 , a flow control switch  219  is provided within the handle of the housing in order to enable the flow of pressurized air from air supply to the reciprocation means (e.g., cylinder  182 , etc.) only when manually actuated trigger  138  is manually actuated (or a foot pedal is depressed). When the trigger  138  is pulled, an electrical signal is sent to the flow control switch  219 , which, in turn, permits a selected amount of pressurized air to flow into the reciprocation device (e.g., cylinder  182 ). The trigger switch  138  can have a number of positions, at which different electrical signals are produced for enabling flow control switch  219  to allow pressured air to flow to the reciprocation means  182  at different flow rates. This can be used to control the rate of reciprocation of the inner cannula relative to the outer cannula, providing the surgeon with additional control over the tissue aspiration process.  
      Notably, an improved degree of surgical control and user safety is provided by the liposuction instrument of the present invention described above.  
      In particular, control circuit  217  prevents the liposuction instrument hereof from carrying out cauterization along the length of its cannula assembly, unless the cannula is reciprocating and/or aspirating. This condition is detected when the trigger  138  is pulled to a particular degree of angular deflection. The reason for providing such control over the electro-cauterization functionality of the liposuction device hereof is to prevent inadvertent burning of tissue during liposuction and like procedures.  
      The function of the control logic circuit  215  is to enable the commutation of 20-25 kilohertz electrical signals between the generator  216  and the power supply rails  213 A and  213 B (to energize the piezo-electric transducers  210  in the base portion of the inner cannula) only when aspirated tissue is flowing through the inner cannula. This condition is detected when the trigger  138  is pulled to a particular degree of angular deflection.  
      The electro-cauterization electrodes of the liposuction devices hereof can be controlled in a variety of different ways. One way would be to continuously enable RF-based electro-cauterization during sensed tissue aspiration. In such “continuously-enabled” embodiments of the present invention, there will typically be no need for external switches to activate the electro-cauterizing electrodes embodied within the cannula assembly of the present invention.  
      Another way would be to enable RF-based electro-cauterization by way of switching RF supply and return signals to the electrodes during sensed tissue aspiration and the supply of an activation signal by the surgeon. Generation of the activation signal can be realized by manually actuating a second trigger, or pushing a button, or depressing a foot pedal, external to the hand-supportable housing, or by automatically detecting a particular condition along the aspiration channel of the device or elsewhere therein.  
      While the liposuction instruments described above have been shown to include four symmetrically arranged aspiration apertures, it may be desired in particular applications to provide a cannula assembly having inner and outer cannulas with one, two or three aspiration apertures, rather than four as shown in the illustrative embodiments.  
      In some applications it may be desired to provide a cannula assembly having a pair of diametrically opposed aspiration apertures, and an outer cannula with a single aspiration aperture. The outer cannula assembly can be adapted to be rotatable in one of two angular positions about the inner cannula. In the first position, the single aspiration aperture formed in the outer cannula is aligned in registration with the first aspiration aperture along the inner cannula. When rotated into its second angular position, the single aspiration aperture of the outer cannula is aligned in registration with the second aspiration aperture along the inner cannula. The surgeon can easily switch the outer cannula between its first and second angular positions by rotating a small radially extending projection, adjacent to the hand-holdable housing, in either a clockwise or counter-clockwise direction to align the aspiration aperture on the outer cannula in registration with the selected aspiration aperture on the inner cannula. This feature of the present invention provides the surgeon with the option of changing which side of the distal end of the cannula assembly is enabled to aspirate tissue during a liposuction procedure without the necessity of removing, repositioning and reinserting the cannula assembly within the housing. This technical feature can be used in conjunction with both electro-cauterizing as well as ultrasonic cauterizing functionalities of the present invention described above. When this aspiration aperture orientation control feature is provided in a liposuction instrument of the present invention having cauterizing electrodes embedded about the aspiration aperture(s) of a plastic outer cannula, an electrical communication mechanism can be embodied within the outer cannula in the proximal portion thereof and in its base portion, so that electrical connectivity can be achieved between the cauterizing electrode on the outer cannula and its electrically conductive contact pad embedded within the base portion of the outer cannula.  
      While the particular embodiments shown and described above have proven to be useful in many applications in the liposuction art, further modifications of the present invention herein disclosed will occur to persons skilled in the art to which the present invention pertains. All such modifications are deemed to be within the scope and spirit of the present invention as defined by the appended claims.