Abstract:
An electrode especially useful for RF skin tightening procedures is characterized by an active front that is conical in part with the conical surface having a cone angle that is shallower than the corresponding angle in known electrodes. Preferably, the electrode of the invention has a conical section whose surface forms an angle greater than 60 degrees with the longitudinal axis of the electrode, and the outside diameter of the conical section is greater than 50% of the overall outside diameter of the electrode.

Description:
[0001]    This invention relates to a device and a procedure for cosmetic rejuvenation, and in particular to such device and procedure for treating skin tissue using non-ablative radio-frequency (RF) energy. 
       BACKGROUND OF THE INVENTION 
       [0002]    A commonly-assigned copending application Ser. No. 11/709,672, filed Feb. 23, 2007, the contents of which are herein incorporated by reference, describes an electrode configuration and RF procedure for use for topical application to the tissue surface or skin of a patient for the non-ablative removal of wrinkles or other cosmetic rejuvenation or skin tightening procedures to improve the appearance of skin tissue. In this RF procedure employing RF energy from an RF generator, it is desirable to raise the tissue temperature to about 41-65° C. to affect underlying skin collagen to tighten the surface tissue, being careful to avoid overheating the skin tissue possibly causing burns and residual scarring. As described in this prior application, preferably a dome shaped electrode is employed while pre-applying to the skin a thermal gel, a known thermally and electrically-conductive material, to help cool the surface. The assignee Ellman International, Inc. of Oceanside, N.Y. has also marketed for this purpose under the name RADIAGE an electrosurgical handpiece known as a wand with a built in dome-shaped or ball electrode for use together with a thermal gel to help cool the surface. 
       SUMMARY OF THE INVENTION 
       [0003]    An object of the present invention is to employ RF energy for skin conditioning with an improved non-ablative electrode in a handpiece for supplying RF energy to the electrode while carrying out an improved cosmetic skin-rejuvenation procedure. 
         [0004]    A further object of the invention is cosmetic skin-tightening procedure requiring reduced time and generator power settings without the aid of an active cooling mechanism. 
         [0005]    These and other objects of the invention are achieved with a novel RF electrode shape with which sufficient RF energy can be applied to a patient&#39;s skin to heat skin collagen and tighten the skin without the aid of an active cooling mechanism but still maintain the skin surface at a low enough temperature to avoid burns to the skin surface. 
         [0006]    As a further feature of the invention, these results are achieved with a simple lubricating gel that does not provide an endothermic effect to cool, the skin as the gel is free of chondroitin sulfate (or other glycosaminoglcan) or animal protein commonly found in thermal gels. 
         [0007]    A preferred electrode embodiment of the invention is characterized by an active front surface that is conical in part with the conical surface having a cone angle that is shallower than the corresponding angle in the known dome-shaped electrode. 
         [0008]    Preferably, the electrode of the invention has a conical section whose surface forms an angle greater than 60 degrees with the longitudinal axis of the electrode, and the outside diameter of the conical section is greater than 50% of the overall outside diameter of the electrode. In a further preferred embodiment, the outside diameter of the conical surface is greater than 0.3 inches. Looked at from the front, in accordance with a further feature of the invention, the center of the electrode active surface preferably has a small flat, or curved with greater than 0.025″ inside radius, surface leading into the conical section which extends symmetrically rearward from the flat. 
         [0009]    The longitudinal axis of the electrode is defined to mean the center line of the electrode head and shank. The front surface of the head, the active surface of the electrode to be placed in contact with the patient&#39;s tissue, is symmetrical about the longitudinal axis. The outside diameter measurements are taken in a plane perpendicular to the longitudinal axis. The conical surface preferably terminates at a rounded section whose outside diameter is the overall outside diameter of the electrode. 
         [0010]    This novel electrode shape offers several important advantages in a skin tightening procedure. It provides the physician with the ability to apply slightly more intense energy to the tissue being treated by using the small flat or small radiused surface in front and none of or at most a small part only of the surrounding conical surface, whereas by using the flat or radiused surface in front as well as the entire conical surface the physician is provided with the ability to apply a slightly less intense energy to the tissue being treated. This allows the physician to exercise more control over the RF energy density as applied to different skin areas that require less or more RF treatment. In addition, lower power settings can be used for the same results as heretofore and thus it appears that the skin of the patient can be maintained at a lower temperature not requiring the use of active cooling to prevent patient burn. Thus the thermal gel previously recommended can be replaced with a less expensive gel free of the expensive cooling ingredients and that merely acts as a lubricant. A typical gel that can be used contains merely water, a preservative, a thickening agent to stabilize the emulsion, and a hygroscopic agent to aid in wetting the skin. 
         [0011]    The various schemes described in the incorporated application disclosures can also be used in the procedure of the present invention, specifically, preferably employing a highly electrically conductive electrode material, and continuously manually moving the activated electrode while in contact with the skin. 
         [0012]    Skin tightening employing non-ablative RF is preferred as it is believed that the RF technology produces an electric current that generates heat through resistance in the dermis and subcutaneous skin tissue. The thermal effect depends on the conductivity features of the treated tissue. Collagen fibrils, when heated, will tend to denature and contract, which is believed to lead to the observed tissue tightening. Non-ablative RF treatment has a lower risk of complications, shorter recovery time, and less disruption of regular activities than other skin tightening procedures. 
         [0013]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention, like reference numerals designating the same or similar elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    In the drawings: 
           [0015]      FIG. 1  is a side schematic view of one form of electrode according to the invention, shown schematically connected to an RF generator of a known type; 
           [0016]      FIG. 2  is front view (from the left of  FIG. 1 ) of the electrode of  FIG. 1 ; 
           [0017]      FIG. 3  is a side view of another form of electrode according to the invention; 
           [0018]      FIG. 4  is a front view (from the left of  FIG. 3 ) of the electrode of  FIG. 3 ; 
           [0019]      FIG. 5  is a side view of still another form of electrode according to the invention; 
           [0020]      FIG. 6  is a front view (from the left of  FIG. 5 ) of the electrode of  FIG. 5 ; 
           [0021]      FIG. 7  is a side view of still another form of electrode according to the invention; 
           [0022]      FIG. 8  is a front view (from the left of  FIG. 7 ) of the electrode of  FIG. 7 ; 
           [0023]      FIG. 9  is a graph plotting surface temperature rise as a function of increasing RF power being applied to a tissue specimen for a 30 second interval; 
           [0024]      FIG. 10  is a graph plotting surface temperature rise as a function of increasing RF power being applied to a tissue specimen for a 45 second interval; 
           [0025]      FIG. 11  is a graph plotting surface temperature rise as a function of increasing RF power being applied to a tissue specimen for a 60 second interval. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0026]      FIGS. 1 and 2  illustrate a medium size electrode, e.g., 15 mm;  FIGS. 3 and 4  illustrate a smaller sized electrode, e.g., 10 mm;  FIGS. 5 and 6  illustrate the largest size electrode, e.g., 20 mm;  FIGS. 7 and 8  illustrate the smallest sized electrode, e.g., 5 mm, of a family of electrodes used by a physician in RF skin tightening procedures. At least the outer surface of all electrodes are electrically-conductive for a thickness of at least the skin depth of the operating frequency, preferably made of a highly conductive metal, though the electrode can be made wholly of the metal. 
         [0027]      FIGS. 1 and 2  illustrate a medium sized electrode  10 , e.g., 15 mm diameter. It is shown mounted in a handpiece  12  (shown schematically in dashed lines), and connected via a standard cable  14  to a conventional RF generator  16 . The electrode  10  and its shank  18  have a common longitudinal axis  20 . The active surface of the electrode is the front-facing surface  22  which is symmetrical about the longitudinal axis  20 . The active surface  22  comprises a small flat  24  at the center surrounded by a conical surface  26 . The largest or outside diameter of the conical surface is designated  30  and for the embodiment shown is about 0.388 inches, the largest or outside diameter of the electrode, i.e., the overall diameter measured in a plane perpendicular to the longitudinal axis, is designated  32  and for the embodiment shown is about 0.59. Thus, the largest cone diameter is about 66% of the largest electrode diameter. The diameter of the small flat  24  at the front is designated  36 , and for the embodiment shown is about 0.031 inches. The flat  24  lies in a plane perpendicular to the longitudinal axis, and the conical surface forms a shallow angle designated  38  with the longitudinal axis for the embodiment shown of about 75°. 
         [0028]    The corresponding dimensions of the electrode shown in  FIGS. 3 and 4 , for the 10 mm diameter electrode, are as follows (the same reference numerals are used for corresponding electrode parts): the largest diameter  30  of the conical surface is about 0.33 inches; the largest diameter  32  of the electrode is about 0.39; the largest cone diameter is about 83% of the largest electrode diameter. The diameter of the small flat  24  at the front is designated  36 , and for the embodiment shown is about 0.031 inches. The conical surface forms a shallow angle designated  38  with the longitudinal axis of about 75°. 
         [0029]    The corresponding dimensions of the electrode shown in  FIGS. 5 and 6 , for the 20 mm diameter electrode, are as follows (the same reference numerals are used for corresponding electrode parts): the largest diameter  30  of the conical surface is about 0.47 inches; the largest diameter  32  of the electrode is about 0.78; the largest cone diameter is about 60% of the largest electrode diameter. The diameter of the small flat  24  at the front is designated  36 , and for the embodiment shown is about 0.031 inches. The conical surface forms a shallow angle designated  38  with the longitudinal axis of about 80°. 
         [0030]    For these three electrode dimensions, the 10, 15 and 20 mm, the diameter  24  of the small flat is less than 10% of the diameter  30  of the largest diameter of the conical section. The values are 9.5, 8.0, and 6.6% of the conical diameter, respectively. Preferably, for electrodes equal to or greater than 8 mm, it is preferred that the diameter  24  of the small flat is between 5 and 10% of the diameter  30  of the largest diameter of the conical section, so that enough of the flat is available for more intense heating, while maintaining most of the available active surface conically shaped for less intense heating which is the more common procedure. 
         [0031]    The front section, instead of flat, can also be a small curved (concave) surface with an inside radius exceeding 0.025 inches. So, as with the flat section, when used alone, more intense heating but not over-heating is achieved. Preferably, the front section if curved has a surface area that is less than 10% of the surface area of the conical surface. Preferably, when the overall diameter of the electrode is greater than 8 mm, and the active surface in front is curved, it has a diameter that is between 5 and 10% of the widest part of the conical surface. 
         [0032]    The corresponding dimensions of the electrode shown in  FIGS. 7 and 8 , for the 5 mm diameter electrode, are as follows (the same reference numerals are used for corresponding electrode parts): the largest diameter  30  of the conical surface is about 0.14 inches; the largest diameter  32  of the electrode is about 0.2 inches; the largest cone diameter is about 70% of the largest electrode diameter. Since the dimensions of the 5 mm electrode are so small, the diameter of the flat in front approaches zero, and virtually blends in to the conical section. The conical surface forms a shallow angle designated  38  with the longitudinal axis of about 85°. 
         [0033]    The important features are the shallow angled conical surface which cooperates with the small flat or small radiused curved surface in front such that the physician can control more accurately the RF energy density at the tissue surface. By the physician positioning the active electrode surface such that only the small flat or curved front section is in contact with the skin, the RF energy density can be maximized for the same power settings because the RF currents exit only via the small surface area of the front section. On the other hand, when the physician positions the active electrode surface such that not only the flat or curved front section but also the conical section is in contact with the skin, the RF energy density can be minimized for the same power settings because the RF currents exit now via a much larger surface area of the combined flat or curved and conical sections. This takes advantage of the resilience of the skin tissue that allows the contacted electrode surface area to be controlled due to the shallow cone angle present. 
         [0034]    It has also been found that the new geometry described herein also offers the advantage of maintaining the skin surface at lower temperatures thus avoiding the use of active cooling means to prevent burns. An ordinary lubricating gel lacking any special cooling ingredients can be used to lower costs. 
         [0035]    Tests have been conducted comparing the heating effect on tissue of a 10 mm RADIAGE dome electrode and the electrode in accordance with the invention. The RADIAGE dome electrode is an electrode currently sold by Ellman International, Inc. of Oceanside, N.Y. for purposes of cosmetic rejuvenation. Its dimensions are as follows: The dome electrode&#39;s outside diameter is 0.39 inches. It has an inner 0.29 inch diameter region where the dome has a 0.27 inch radius. The region between the diameters of 0.29 inch and 0.39 inch is a surface with a 0.10 inch radius which continues to the backside of the electrode. The 0.27 inch and 0.10 inch radiuses are blended together at their transition. 
         [0036]    The tests were conducted on a piece of beef using the 10 mm RADIAGE dome electrode described above and a 10 mm electrode as described herein in accordance with the invention with the new non-cooling gel for both electrodes. The surface temperature was measured with an IR sensor immediately before and after applying RF energy from a standard RF generator at 4.0 MHz, in this instance made by Ellman International, Inc. of Oceanside, N.Y. 
         [0037]    The graphs of  FIGS. 9-11  show the results; plots of the temperature rise of the specimen measured with increasing power applied for 30, 45, and 60 seconds. In the graphs, the diamond points represent measurements taken with the known RADIAGE dome electrode with the dashed line representing the linear least squared regression of those data points with zero intercept, whereas the square points represent measurements taken with the electrode in accordance with the invention with the dotted line representing the linear least squared regression of those data points with zero intercept. The slopes of the regressions for the known dome electrode are 0.23, 0.32, and 0.38 for the temperature rise after 30, 45, and 60 seconds. The slopes of the regressions for the 10 mm inventive electrode are 0.10, 0.17, 0.22, for the temperature rise after 30, 45, and 60 seconds. As will be noted, the electrode in accordance with the invention produces significantly less surface temperature elevation supporting the reduced need for active surface cooling. 
         [0038]    The RF generator used preferably output RF currents in the range of about 0.2-10 MHz. Continuous wave power can be used. 
         [0039]    While the invention has been described in connection with preferred embodiments, it will be understood that modifications thereof within the principles outlined above will be evident to those skilled in the art and thus the invention is not limited to the preferred embodiments but is intended to encompass such modifications.