Patent Abstract:
A sheath system for selectively covering a distal end of an electrocautery blade is provided. The sheath system includes a hub having a body portion defining a lumen therethrough and a sheath having a body portion defining a lumen therethrough. The lumen of the sheath is configured and dimensioned to operatively receive an electrocautery blade therein. The sheath is translatably associated with the hub such that rotation of the hub in a first direction results in axial movement of the sheath in a first direction to expose a distal end of the electrocautery blade and rotation of the hub in a second direction, opposite to the first direction, results in axial movement of the sheath in a second direction to cover the distal end of the electrocautery blade. The hub and the sheath may be concentric with one another.

Full Description:
BACKGROUND 
   1. Technical Field 
   The present disclosure relates generally to electrosurgical instruments and, more particularly, to an electrode including a selectively deployable protective sheath. 
   2. Background of Related Art 
   Electrosurgical instruments have become widely used by surgeons in recent years. Accordingly, a need has developed for equipment and instruments which are easy to handle, are reliable and are safe in an operating environment. By and large, most electrosurgical instruments are hand-held instruments, e.g., an electrosurgical pencil, which transfer radio-frequency (RF) electrical or electrosurgical energy to a tissue site. The electrosurgical energy is returned to the electrosurgical source via a return electrode pad positioned under a patient (i.e., a monopolar system configuration) or a smaller return electrode positionable in bodily contact with or immediately adjacent to the surgical site (i.e., a bipolar system configuration). The waveforms produced by the RF source yield a predetermined electrosurgical effect known generally as electrosurgical cutting and fulguration. 
   In particular, electrosurgical fulguration includes the application of electric spark to biological tissue, for example, human flesh or the tissue of internal organs, without significant cutting. The spark is produced by bursts of radio-frequency electrical or electrosurgical energy generated from an appropriate electrosurgical generator. Coagulation is defined as a process of desiccating tissue wherein the tissue cells are ruptured and dehydrated/dried. Electrosurgical cutting/dissecting, on the other hand, includes applying an electrical spark to tissue in order to produce a cutting, dissecting and/or dividing effect. Blending includes the function of cutting/dissecting combined with the production of a hemostasis effect. Meanwhile, sealing/hemostasis is defined as the process of liquefying the collagen in the tissue so that it forms into a fused mass. 
   As used herein the term “electrosurgical pencil” is intended to include instruments which have a handpiece which is attached to an active electrode and which is used to cauterize, coagulate and/or cut tissue. Typically, the electrosurgical pencil may be operated by a handswitch or a foot switch. The active electrode is an electrically conducting element which is usually elongated and may be in the form of a thin flat blade with a pointed or rounded distal end. Alternatively, the active electrode may include an elongated narrow cylindrical needle which is solid or hollow with a flat, rounded, pointed or slanted distal end. Typically electrodes of this sort are known in the art as “blade”, “loop” or “snare”, “needle” or “ball” electrodes. 
   As mentioned above, the handpiece of the electrosurgical pencil is connected to a suitable electrosurgical energy source (i.e., generator) which produces the radio-frequency electrical energy necessary for the operation of the electrosurgical pencil. In general, when an operation is performed on a patient with an electrosurgical pencil, electrical energy from the electrosurgical generator is conducted through the active electrode to the tissue at the site of the operation and then through the patient to a return electrode. The return electrode is typically placed at a convenient place on the patient&#39;s body and is attached to the generator by a conductive material. Typically, the surgeon activates the controls on the electrosurgical pencil to select the modes/waveforms to achieve a desired surgical effect. Typically, the “modes” relate to the various electrical waveforms, e.g., a cutting waveform has a tendency to cut tissue, a coagulating wave form has a tendency to coagulate tissue, and a blend wave form tends to be somewhere between a cut and coagulate wave from. The power or energy parameters are typically controlled from outside the sterile field which requires an intermediary like a circulating nurse to make such adjustment. 
   A typical electrosurgical generator has numerous controls for selecting an electrosurgical output. For example, the surgeon can select various surgical “modes” to treat tissue: cut, blend (blend levels 1-3), low cut, desiccate, fulgurate, spray, etc. The surgeon also has the option of selecting a range of power settings typically ranging from 1-300 W. As can be appreciated, this gives the surgeon a great deal of variety when treating tissue. 
   In particular with the use of active electrodes having a sharpened or pointed tip, a need exists for electrosurgical instruments (i.e., electrosurgical pencils) including incorporated safety features, elements and/or systems to protect the user from inadvertent or accidental pricking and/or stabbing by the active electrode. 
   SUMMARY 
   According to an aspect of the present disclosure, a sheath system for selectively covering a distal end of an electrocautery blade is provided. The sheath system includes a hub having a body portion defining a lumen therethrough; and a sheath having a body portion defining a lumen therethrough. The lumen of the sheath is configured and dimensioned to operatively receive an electrocautery blade therein. The sheath is translatably associated with the hub such that rotation of the hub in a first direction results in axial movement of the sheath in a first direction to expose a distal end of the electrocautery blade and rotation of the hub in a second direction, opposite to the first direction, results in axial movement of the sheath in a second direction to cover the distal end of the electrocautery blade. It is envisioned that the hub and the sheath are concentric with one another. 
   The body portion of the hub may include at least one helical groove formed in an inner surface thereof. Meanwhile, the body portion of the sheath includes at least one nub extending from an outer surface thereof. The nub may be configured and dimensioned to slidably engage the groove of the hub. Accordingly, as the hub is rotated, the nub of the sheath rides along the helical groove of the hub to translate the sheath in one of a distal and proximal direction. 
   The sheath system further includes a collar configured and dimensioned to support the electrocautery blade. Each of a distal end and a proximal end of the electrocautery blade extends from a respective distal and proximal end of the collar. At least a portion of the collar is rotatably supported in the body portion of the hub and a portion of the collar is disposed in the lumen of the sheath. The collar may include an annular flange extending from an outer surface thereof, and the hub may include an annular groove formed in an inner surface of the body portion. As such, the annular groove of the hub is configured and dimensioned to slidably receive the annular flange of the collar. 
   It is envisioned that the body portion of the sheath may include an elongated slot formed therein and the collar may include a stub extending from the outer surface thereof. In an embodiment, the stub of the collar is configured and dimensioned to slidably engage the elongated slot formed in the body portion of the sheath. Accordingly, the inter-engagement of the stub of the collar in the elongate slot of the sheath prevents rotation of the sheath as the hub is rotated. 
   It is contemplated that at least a portion of each of the hub, the sheath and the connector is fabricated from non-conductive materials. It is further contemplated that the body portion of the hub includes finger grips. 
   According to another aspect of the present disclosure, a sheath system for selectively covering a distal end of an electrocautery blade is provided. The sheath system includes a hub having a body portion defining a lumen therethrough. The body portion of the hub includes a helical groove and an annular groove formed therein. The annular groove is formed at a location proximal of the helical groove. 
   The sheath system further includes a sheath having a body portion defining a lumen therethrough. The body portion of the sheath includes a nub extending from an outer surface thereof, wherein the nub is configured and dimensioned to slidably engage the helical groove formed in the hub; and an elongated slot formed therein. The sheath is translatably associated with the hub such that rotation of the hub in a first direction results in axial movement of the sheath in a first direction to expose a distal end of the electrocautery blade and rotation of the hub in a second direction, opposite to the first direction, results in axial movement of the sheath in a second direction to cover the distal end of the electrocautery blade. 
   The sheath system further includes a collar configured and dimensioned for support on the electrocautery blade. A distal end and a proximal end of the electrocautery blade each extend from a respective distal end and proximal end of the collar. It is envisioned that at least a portion of the collar is rotatably supported in the body portion of the hub and a portion of the collar is disposed in the lumen of the sheath. The collar desirably includes an annular flange extending from an outer surface thereof for slidable engagement in the annular groove formed in the hub; and a stub extending from the outer surface of thereof at a location distal of the annular flange for slidable engagement in the elongate slot of the sheath. Accordingly, rotation of the hub a first direction results in axial movement of the sheath in a first direction to expose a distal end of the electrocautery blade and rotation of the hub in a second direction, opposite to the first direction, results in axial movement of the sheath in a second direction to cover the distal end of the electrocautery blade. 
   It is envisioned that the hub, the sheath, and the collar are concentric with one another. It is contemplated that at least a portion of each of the hub, the sheath and the connector is fabricated from non-conductive materials. Desirably, the body portion of the hub includes finger grips. 
   In operation, as the hub is rotated, the nub of the sheath rides along the helical groove of the hub to translate the sheath in one of a distal and proximal direction. Additionally, the inter-engagement of the stub of the collar in the elongated slot of the sheath prevents the rotation of the sheath as the hub is rotated. 
   According to yet another aspect of the present disclosure, an electrosurgical pencil for electrical connection to an electrosurgical generator is provided. The electrosurgical pencil includes an elongate housing; an electrocautery blade including a proximal end supported in the housing, and a distal end extending distally from the housing, the electrocautery blade being electrically connectable with the electrosurgical generator; at least one activation switch supported on the housing, each activation switch being configured and adapted to selectively activate the electrosurgical pencil; and a sheath system for selectively covering and exposing the distal end of the electrocautery blade. 
   The sheath system includes a hub having a body portion defining a lumen therethrough; and a sheath including a body portion defining a lumen therethrough. The lumen of the sheath is configured and dimensioned to operatively receive the electrocautery blade therein. The sheath is translatably associated with the hub such that rotation of the hub in a first direction results in axial movement of the sheath in a first direction to expose the distal end of the electrocautery blade and rotation of the hub in a second direction, opposite to the first direction, results in axial movement of the sheath in a second direction to cover the distal end of the electrocautery blade. 
   In this embodiment, it is envisioned that the hub and the sheath are concentric with one another. 
   The body portion of the hub may include at least one helical groove formed in an inner surface thereof; and the body portion of the sheath desirably includes at least one nub extending from an outer surface thereof. It is envisioned that the nub is configured and dimensioned to slidably engage the groove of the hub. Accordingly, as the hub is rotated, the nub of the sheath rides along the helical groove of the hub to translate the sheath in one of a distal and proximal direction. 
   The sheath system further includes a collar configured and dimensioned for support on the electrocautery blade, wherein each of the distal end and the proximal end of the electrocautery blade extends from a respective distal and proximal end of the collar. At least a portion of the collar is rotatably supported in the body portion of the hub and at least a portion of the collar is disposed in the lumen of the sheath. 
   Desirably, the collar includes an annular flange extending from an outer surface thereof, and the hub desirably includes an annular groove formed in an inner surface of the body portion. It is envisioned that the annular groove of the hub is configured and dimensioned to slidably receive the annular flange of the collar. 
   Desirably, the body portion of the sheath includes an elongate slot formed therein, and the collar includes a stub extending from the outer surface thereof. It is envisioned that the stub of the collar is configured and dimensioned to slidably engage the elongate slot formed in the body portion of the sheath. In use, the inter-engagement of the stub of the collar in the elongate slot of the sheath prevents the rotation of the sheath as the hub is rotated. 
   According to still another aspect of the present disclosure, a sheath system for selectively covering a distal end of an electrocautery blade is provided. It is envisioned that the electrocautery blade may be electrically connectable to an electrosurgical device and may be capable of transmitting electrosurgical energy. The sheath system includes an electrocautery blade having a distal end and a proximal end; a collar configured and dimensioned for support on the electrocautery blade; a sheath operatively supported on a distal end of the collar; and a hub operatively supported on the sheath and on a proximal end of the collar. 
   Desirably, the distal end and the proximal end of the electrocautery blade each extend from a respective distal and proximal end of the collar. The collar includes an annular flange extending from an outer surface thereof; and a stub extending from the outer surface thereof at a location distal of the annular flange. 
   Desirably, the sheath includes a body portion defining a lumen therethrough; a nub extending from an outer surface of the body portion of the sheath; and an elongated slot formed in the body portion of the sheath for slidably receiving the stub of the collar therein. 
   Desirably, the hub includes a body portion defining a lumen therethrough. The body portion of the hub includes a helical groove formed therein for slidably engaging the nub of the collar and an annular groove formed therein for rotatably receiving the annular flange of the collar. The annular groove is formed at a location proximal of the helical groove. 
   Desirably, the sheath is translatably associated with the hub such that rotation of the hub in a first direction results in axial movement of the sheath in a first direction to expose a distal end of the electrocautery blade, and rotation of the hub in a second direction, opposite to the first direction, results in axial movement of the sheath in a second direction to cover the distal end of the electrocautery blade. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
       FIG. 1  is a perspective view of a typical electrosurgical system; 
       FIG. 2  is a perspective view, with parts separated, of the sheath system of  FIG. 1 ; 
       FIG. 3  is a perspective view of a distal end of an electrosurgical pencil of  FIG. 1  illustrating the sheath system in a deployed or covering position; 
       FIG. 4  is a perspective view of the distal end of the electrosurgical pencil of  FIG. 1  illustrating the sheath system in a retracted or exposing condition; 
       FIG. 5  is an enlarged perspective view of the sheath system of  FIGS. 2-4 , shown in the deployed or covering position; 
       FIG. 6  is an enlarged perspective view of the sheath system of  FIGS. 2-5 , shown in the retracted or exposing condition; 
       FIG. 7  is a rear, perspective, partial cross-sectional view of the sheath system of  FIGS. 2-6 ; and 
       FIG. 8  is a perspective view of a distal end of an electrosurgical pencil of  FIG. 1  illustrating the hub of the sheath system in a separated condition. 
   

   DETAILED DESCRIPTION 
   Particular embodiments of the presently disclosed electrosurgical pencil and sheath system will now be described in detail with reference to the drawing figures wherein like reference numerals identify similar or identical elements. As used herein, the term “distal” refers to that portion which is further from the user while the term “proximal” refers to that portion which is closer to the user or surgeon. 
   Referring initially to  FIG. 1 , there is seen a perspective view of an electrosurgical instrument system in accordance with an embodiment of the present disclosure, generally indicated as reference numeral  10 . Electrosurgical instrument system  10  includes an electrosurgical instrument  100  constructed in accordance with an embodiment of the present disclosure. While the following description will be directed towards electrosurgical pencils including sharpened or pointed electrocautery blades and the like, it is envisioned that the features and concepts (or portions thereof) of the present disclosure can be applied to electrosurgical pencils including any type of electrocautery blade. 
   Electrosurgical pencil  100  includes a housing  102  configured and adapted to support a sheath system  200  ( FIGS. 2-8 ) at a distal end thereof which, in turn, receives a replaceable electrode or electrocautery blade  120  therein. Electrosurgical pencil  100  further includes at least one activation button  104  supported on an outer surface of housing  102 . Activation button(s)  104  are operable to control the supply of RF electrical energy to blade  120  from an electrosurgical generator “G”. Electrosurgical pencil  100  may be coupled to electrosurgical generator “G” via a plug assembly  140 . 
   Other electrosurgical pencils which may incorporate and/or include the sheath system disclosed herein are identified in U.S. patent application Ser. No. 10/959,824, filed on Oct. 6, 2004, entitled “Electrosurgical Pencil with Improved Controls”; and International Application No. PCT/US03/37111, filed on Nov. 20, 2003, also entitled “Electrosurgical Pencil with Improved Controls”, the entire contents of each of which being incorporated by reference herein. 
   By way of example only, electrosurgical generator “G” may be any one of the following, or equivalents thereof: the “FORCE FX”, “FORCE 2” or “FORCE 4” generators manufactured by Valleylab, Inc. of Boulder, Colo., a Division of Tyco Healthcare LP. It is contemplated that electrosurgical generator “G” can be preset to selectively provide an appropriate first predetermined RF signal (e.g., about 1 to 300 watts) for tissue cutting and an appropriate second predetermined RF signal (e.g., about 1 to 120 watts) for tissue coagulation. However, electrosurgical generator “G” may be adapted to automatically configure itself to transmit particular RF signals depending on the particular electrosurgical instrument connected thereto. 
   Turning now to  FIGS. 2-8 , a sheath system for electrosurgical pencil  100 , in accordance with an embodiment of the present disclosure, is generally designated as  200 . Sheath system  200  is operatively supportable on a distal end of housing  102  of electrosurgical pencil  100 . Sheath system  200  includes at least a first position in which sheath system  200  is deployed to completely cover electrocautery blade  120 , as seen in  FIGS. 3 and 5 , and a second position in which sheath system  200  is retracted to expose electrocautery blade  120 , as seen in  FIGS. 4 and 6 . 
   As seen in  FIGS. 2 ,  7  and  8 , sheath system  200  includes an elongate collar  210  configured and dimensioned to receive and support electrocautery blade  120 . Desirably, collar  210  is dimensioned such that a distal end  120   a  of electrocautery blade  120  extends from a distal end  210   a  thereof, and a proximal end  120   b  of electrocautery blade  120  extends from a proximal end  210   b  thereof. Collar  210  includes an annular flange  212  extending therearound. 
   As seen in  FIGS. 2-8 , sheath system  200  further includes a hub  220  rotatably supportable at the distal end of housing  102 ; and a protective sheath  240  operatively connected to hub  220  in such a manner that as hub  220  is rotated, sheath  240  is displaced axially (i.e., either proximally or distally). As seen in  FIG. 7 , hub  220  includes an internal annular groove  224  formed in a body portion  222  thereof for rotatably receiving and supporting annular flange  212  of collar  210 . 
   Body portion  222  of hub  220  includes a substantially cylindrical distal portion  222   a  and a flared or substantially frusto-conical proximal portion  222   b . Flared proximal portion  222   b  is configured and dimensioned to approximate the taper and/or outer profile of the distal end of housing  102  of electrosurgical pencil  100 . As mentioned above, collar  210  and, in turn, electrocautery blade  120 , is rotatably supported in a lumen  228  defined by body portion  222  of hub  220 . 
   As seen in  FIGS. 7 and 8 , hub  220  includes a helical groove  226  formed along an inner periphery thereof. Helical groove  226  is formed in an inner surface of distal portion  222   a  at a location distal to annular groove  224 . 
   With continued reference to  FIGS. 2-8 , sheath  240  includes a body portion  242  defining a lumen  244  therethrough. Body portion  242  of sheath  240  desirably includes a tapered distal portion  242   a , and a substantially cylindrical proximal portion  242   b . Lumen  244  of sheath  240  is configured and dimensioned to operatively receive distal end  120   a  of electrocautery blade  120  and distal end  210   a  of collar  210  therein. 
   As seen in  FIGS. 2 ,  7  and  8 , sheath  240  includes at least one nub  246  projecting from an outer surface of body portion  242 . A pair of diametrically opposed nubs  246  project from proximal portion  242   b  of body portion  242 . Each nub  246  is configured and dimensioned to slidably seat within helical groove  226  formed in the inner surface of body portion  222  of hub  220 . As will be described in greater detail below, nubs  246  cause sheath  240  to move distally and proximally as hub  220  is rotated in a clockwise or counter-clockwise direction. 
   Sheath  240  includes a longitudinally oriented elongate slot  248  formed in at least the proximal portion  242   b  of body portion  242 . Elongate slot  248  is configured and dimensioned to slidably receive a stub  214  projecting from an outer surface of collar  210 . As will be described in greater detail below, stub  214  of collar  210  prevents sheath  240  from rotating about a longitudinal axis as hub  220  is rotated. 
   Sheath  240  includes at least a first position in which sheath  240  is deployed to completely cover electrocautery blade  120 , as seen in  FIGS. 3 and 5 , and at least a second position in which sheath  240  is retracted to expose at least the distal end  120   a  of electrocautery blade  120 , as seen in  FIGS. 4 and 6 . 
   Each of collar  210 , hub  220  and sheath  240  are fabricated from electrically non-conductive and/or insulative materials. In this manner, sheath system  200  does not electrically short electrocautery blade  120 . 
   It is further desired for hub  220  to be provided with finger tabs or grips  229  formed around and along at least a portion of, preferably around and along substantially the entire length, a proximal edge of body portion  222 . Grips  229  increase the users ability to rotate hub  220  about a longitudinal axis relative to housing  102  of electrosurgical pencil  100 . 
   As seen in  FIG. 2 , collar  210 , hub  220  and sheath  240  share a common longitudinal “X” axis. A central axis of electrocautery blade  120  is axially aligned with the longitudinal “X” axis. Additionally, a central axis of collar  210 , a central axis of lumen  228  of hub  220 , and a central axis of lumen  244  of sheath  240  are axially aligned with the longitudinal “X” axis. As will be described in greater detail below, hub  220  is rotatable about the longitudinal “X” axis and sheath  240  is translatable along the longitudinal “X” axis. In an embodiment, sheath  240  is concentrically aligned with hub  220 . 
   When sheath system  200  is in the first or deployed condition, nubs  246  of sheath  240  at located at or near a distal end of helical groove  226  formed in hub  220 . Additionally, stub  214  of collar  210  is located at or near a distal end of elongate slot  248  formed in proximal portion  242   b  of body portion  242 . When sheath system  200  is in the second or retracted condition, nubs  246  of sheath  240  are located at or near a proximal of helical groove  226  formed in hub  220 . Additionally, stub  214  of collar  210  is located at or near a proximal end of elongate slot  248  formed in proximal portion  242   b  of body portion  242 . 
   Sheath system  200  is operatively connected to electrocautery blade  120  in such a manner that proximal end  120   b  of electrocautery blade  120  extends from hub  220 . When electrocautery blade  120  is connected to electrosurgical pencil  100 , sheath system  200  is necessarily operatively associated with electrosurgical pencil  100 . In particular, when electrocautery blade  120  is operatively connected to electrosurgical pencil  100 , proximal end  120   b  of electrocautery blade  120  enters an open distal end of housing  102  of electrosurgical pencil  100  and electrically engages and/or is connected to a blade receptacle (not shown) provided in electrosurgical pencil  100 . A shaped portion  211   b , preferably hex-shaped, of a proximal end  210   b  of collar  210  engages a complementary shaped recess (not shown) formed in housing  102  of electrosurgical pencil  100  to prevent rotation of blade  120  when properly coupled thereto. Additionally, a distal end of housing  102  of electrosurgical pencil  100  is positioned in lumen  228  of flared proximal portion  222   b  of body portion  222  of hub  220 . 
   With continued reference to  FIGS. 2-8 , a method of operating sheath system  200  to expose and cover distal end  120   a  of electrocautery blade  120  is shown and described. Electrocautery blade  120  may be connected or coupled to and disconnected from electrosurgical pencil  100  when sheath  240  of sheath system  200  is in the deployed and/or extended condition. In this manner, accidental and/or inadvertent incidents of pricking are reduced and/or eliminated. 
   Initially, in order to expose distal end  120   a  of electrocautery blade  120 , if sheath system  200  is in a first or deployed condition, wherein sheath  240  at least completely covers distal end  120   a  of electrocautery blade  120  as seen in  FIGS. 3 and 5 , hub  220  is rotated in a first direction about the longitudinal “X” axis, as indicated by arrow “A” of  FIGS. 3 and 5 . Since stub  248  of collar  210  is slidingly located in elongate slot  248  of collar  210 , upon rotation of hub  220 , in the direction of arrow “A”, helical groove  226  of hub  220  engages nubs  246  and causes sheath  240  to withdraw or retract (i.e., move in a proximal direction as indicated by arrow “B” in  FIGS. 3 and 5 ). With sheath  240  of sheath system  200  in a withdrawn or retracted condition, the user may operate electrosurgical pencil  100  in a standard or normal fashion. 
   Following use of electrosurgical pencil  100 , sheath  240  of sheath system  200  is deployed in order to once again cover distal end  120   a  of electrocautery blade  120 , in order to store electrosurgical pencil  100 , to replace electrocautery blade  120  and/or to discard electrocautery blade  120 . 
   In particular, if sheath system  200  is in a second or retracted condition, wherein sheath  240  at least partially uncovers distal end  120   a  of electrocautery blade  120  as seen in  FIGS. 4 and 6 , in order to recover distal end  120   a  of electrocautery blade  120 , hub  220  is rotated in a second or opposite direction about the longitudinal “X” axis, as indicated by arrow “C” of  FIGS. 4 and 6 . Since stub  248  of collar  210  is slidingly located in elongate slot  248  of collar  210 , upon rotation of hub  220 , in the direction of arrow “C”, helical groove  226  of hub  220  engages nubs  246  and causes sheath  240  to extend (i.e., move in a distal direction as indicated by arrow “D” in  FIGS. 4 and 6 ). With sheath  240  of sheath system  200  in an extended condition, the user may remove electrocautery blade  120  and discard the same with the increased assurance that they will not be stuck or pricked by distal end  120   a  of electrocautery blade  120 . 
   Helical groove  226  formed in body portion  222  of hub  220  may include a notch or catch-point (not shown) formed near a distal end thereof. The notch formed in helical groove  226  is configured and dimensioned to selectively receive a nub  246  of collar  210  when sheath  240  is in the fully deployed and/or extended condition. The notch formed in helical groove  226  desirably functions to prevent and/or reduce the likelihood of sheath  240  from sliding back (i.e., moving in a proximal direction) as a result of a force applied, in a proximal direction, to the distal end thereof. 
   In a further embodiment, hub  220  may include a ratchet or other anti-rotation feature (not shown) which functions to prevent sheath  240  from accidentally or unwantingly sliding proximally thereby exposing distal end  120   a  of electrocautery blade  120 . This anti-rotation feature may only be dis-engageable when electrocautery blade  120  is connected to the distal end of housing  102  of electrosurgical pencil  100 . The components of the anti-rotation feature desirably remain with electrocautery blade  120  when electrocautery blade  120  is removed from electrosurgical pencil  100  to provide continued safe handling of electrocautery blade  120 . 
   In one embodiment, the anti-rotation feature is a flexible pawl (not shown) protruding inwardly from the inner surface of body portion  222  of hub  220  and inter-engaging a toothed ring (not shown) in electrocautery blade  120  or collar  210 . In use, it is envisioned that when the distal end of housing  102  of electrosurgical pencil  100  enters the proximal end of lumen  228  of body portion  222  of hub  220 , housing  102  of electrosurgical pencil lifts the pawl and disengages the pawl from the toothed ring, allowing hub  220  to rotate. 
   While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. 
   Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Technology Classification (CPC): 0