Patent Publication Number: US-11039876-B2

Title: Hand-held instrument with extendable shaft locking mechanism

Description:
BACKGROUND 
     1. Technical Field 
     This disclosure relates to instruments with extendable shafts. More particularly, the disclosure relates to locking mechanisms for locking extendable shafts to instruments and in various positions relative to such instruments. 
     2. The Relevant Technology 
     As is known to those skilled in the art, modern surgical techniques typically employ radio frequency (RF) power to cut tissue and coagulate bleeding encountered in performing surgical procedures. Electrosurgery is widely used and offers many advantages including the use of a single surgical instrument for both cutting and coagulation. A monopolar electrosurgical system has an active electrode, such as in the form of an electrosurgical instrument having a hand piece and a conductive electrode or tip, which is applied by the surgeon to the patient at the surgical site to perform surgery and a return electrode to connect the patient back to the generator. 
     The electrode or tip of the electrosurgical instrument is small at the point of contact with the patient to produce an RF current with a high current density in order to produce a surgical effect of cutting or coagulating tissue. The return electrode carries the same RF current provided to the electrode or tip of the electrosurgical instrument, thus providing a path back to the electrosurgical generator. 
     When an electrosurgical instrument is used for cutting or coagulation, smoke is commonly produced. A surgeon or assistant often uses a separate smoke evacuation device to remove the smoke from the surgical field. Smoke evacuation devices commonly include a suction wand connected to a vacuum device via tubing. The surgeon or assistant holds the suction wand close to the surgical site and the smoke is drawn into the suction wand and through the tubing. However, using a smoke evacuation device separate from the electrosurgical instrument is not ideal. Using a separate smoke evacuation device requires additional hands and instruments near the surgical site, which can obscure the surgeon&#39;s view of the surgical site and reduce the room available around the surgical site for the surgeon to move. 
     As a result, combination electrosurgical instrument and smoke evacuation devices have been developed. These combination devices often include a hand piece that can receive an electrode or tip in a distal end thereof for performing electrosurgical procedures. The hand piece is connected to a generator via a power cable to convey RF current to the electrode or tip. Additionally, a smoke evacuation hose is connected between the hand piece and a vacuum to draw smoke away from the surgical site. 
     Some combination electrosurgical instrument and smoke evacuation devices include an extendable shaft. The electrode or tip can be mounted in the distal end of the shaft, and the shaft can be extended from the hand piece to increase the reach of the device. The extendable shaft may also include an open distal end and conduit therethrough to facilitate the evacuation of smoke through the shaft and the hand piece. 
     Some previous combination devices with extendable shafts include a locking feature for securing the extendable shaft in various extended positions. Such devices and features have various shortcomings. For instance, when the locking feature is loosened or in an unlocked configuration, the extendable shaft can be freely removed from the hand piece. As a result, the device has to be reassembled in order for the device to function properly. In some instances, such as during a surgical procedure, having to reassemble the device can create delays and pose safety risks to the patient. Furthermore, a surgeon or other operating room personnel may not know how to properly reassemble the device. Moreover, attempts to reassemble the device may result in damage to the device which can render the device inoperable. 
     The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only illustrated embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  illustrates an exemplary electrosurgical system; 
         FIG. 2  illustrates an electrosurgical instrument of the system of  FIG. 1  with an extendable shaft in a retracted configuration; 
         FIG. 3  illustrates the electrosurgical instrument of  FIG. 2  with the extendable shaft in an extended configuration; 
         FIG. 4  illustrates a cross-sectional view of the electrosurgical instrument of  FIGS. 2 and 3 , showing the extendable shaft in the retracted configuration; 
         FIG. 5  illustrates a cross-sectional view of the electrosurgical instrument of  FIGS. 2-4 , showing the extendable shaft in the extended configuration; 
         FIG. 6  illustrates the distal end of the electrosurgical instrument of  FIGS. 2-5 , showing a locking mechanism in a locked configuration; 
         FIG. 7  illustrates the distal end of the electrosurgical instrument of  FIGS. 2-5 , showing the locking mechanism in an unlocked configuration; and 
         FIGS. 8-9  illustrate perspective views of the locking mechanism of  FIGS. 6 and 7 , with a locking nut disconnected; 
         FIG. 10A  illustrates a partial cross-sectional view of the locking mechanism showing the interior of the locking nut; 
         10 B illustrates a partial cross-sectional view of another embodiment of a locking mechanism showing the interior of a locking nut; 
         FIG. 11  illustrates a cross-sectional view of the locking mechanism of  FIGS. 7-10A  in an unlocked position; 
         FIG. 12  illustrates a cross-sectional view of the locking mechanism of  FIGS. 7-10A  in a locked position; 
         FIG. 13  illustrates a partially exploded view a portion of a locking mechanism according to another embodiment; 
         FIG. 14  illustrates a perspective view of a locking nut according to an example embodiment; 
         FIG. 15  illustrates a cross-sectional view of the locking nut of  FIG. 14 ; 
         FIG. 16  illustrates a cross-sectional view of a locking mechanism incorporating the locking nut of  FIGS. 14-15  in an unlocked position; and 
         FIG. 17  illustrates a cross-sectional view of a locking mechanism incorporating the locking nut of  FIGS. 14-15  in a locked position. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure relates to locking mechanisms for securing an extendable shaft to an instrument and in various positions relative to the instrument. In some embodiments, the instrument is a hand-held instrument, such as an electrosurgical instrument. In other embodiments, the instrument may not include a hand piece or otherwise be specifically designed as a hand-held instrument. Rather, the instrument may include a body, an extendable shaft, and a locking mechanism as disclosed herein. 
     In some embodiments, the extendable shaft may provide functionality to an implement disposed at the distal end of the shaft. For instance, an electrode tip may be disposed at the distal end of the extendable shaft and electrical current may be communicated to the electrode tip via or through the extendable shaft. 
     In some embodiments, the extendable shaft may provide for the evacuation or delivery of fluid therethrough. For instance, the extendable shaft may have a conduit extending therethrough, through which smoke or other fluids may be evacuated away from a surgical site. The conduit may also be used to deliver fluid to a surgical site. 
     Reference is made herein to the evacuation of smoke and components that facilitate such function. It will be appreciated that references to “smoke” is merely for simplicity and convenience, and is not intended to limit the disclosed and claimed embodiments to evacuation of only smoke. Rather, the disclosed and claimed embodiments may be used to evacuate substantially any type of fluid, including liquids, gases, vapors, smoke, or combinations thereof. Additionally, rather than simply evacuating fluid, it is contemplated that at least some of the embodiments may be used to deliver fluids to a desired location, such as a surgical site. Still further, while the illustrated embodiments include smoke evacuation features and capabilities, it will be appreciated that other embodiments of the present disclosure may not include smoke evacuation features or capabilities. 
       FIG. 1  illustrates an exemplary electrosurgical system  100 . The illustrated embodiment includes a signal generator  102 , an electrosurgical instrument  104 , and a return electrode  106 . Generator  102 , in one embodiment, is an RF wave generator that produces RF electrical energy. Connected to electrosurgical instrument  104  is a utility conduit  108 . In the illustrated embodiment, utility conduit  108  includes a cable  110  that communicates electrical energy from generator  102  to electrosurgical instrument  104 . The illustrated utility conduit  108  also includes a vacuum hose  112  that conveys captured/collected smoke and/or fluid away from a surgical site. In some embodiments, such as that illustrated in  FIG. 1 , cable  110  can extend through at least a portion of vacuum hose  112 . 
     Generally, electrosurgical instrument  104  includes a hand piece  114  and an electrode tip  116 . Electrosurgical instrument  104  communicates electrical energy to a target tissue of a patient to cut the tissue and/or cauterize blood vessels within and/or near the target tissue. Specifically, an electrical discharge is delivered from electrode tip  116  to the patient in order to cause heating of cellular matter of the patient that is in close contact with or proximity to electrode tip  116 . The heating takes place at an appropriately high temperature to allow electrosurgical instrument  104  to be used to perform electrosurgery. Return electrode  106  is connected to generator  102  by a cable  118  in order to complete the circuit and provide a return electrical path to wave generator  102  for energy that passes into the patient&#39;s body. 
       FIGS. 2 and 3  illustrate perspective views of electrosurgical instrument  104  separate from the rest of system  100 . Hand piece  114  of electrosurgical instrument  104  has a proximal end  120  and a distal end  122 . An extendable shaft  124  is selectively extendable from and retractable into (e.g., translatable along an axis running in the proximal/distal direction) distal end  122 .  FIG. 2  illustrates extendable shaft  124  in a retracted position where a substantial portion of extendable shaft  124  is disposed within hand piece  114 . Nevertheless, as can be seen in  FIG. 2 , a portion of extendable shaft  124  can extend out of hand piece  114  even when shaft  124  is in the retracted position. 
     In contrast,  FIG. 3  illustrates extendable shaft  124  in an extended position where a substantial portion of extendable shaft  124  is extended from or disposed outside of hand piece  114 . Even when shaft  124  is in the extended position, a portion of shaft  124  remains disposed within hand piece  114  so that shaft  124  and hand piece  104  remain connected to one another. 
     Although not illustrated, extendable shaft  124  can also be extended from hand piece  114  to various intermediate extended positions between the extended and retracted positions shown in  FIGS. 2 and 3 . In some embodiments, extendable shaft  124  can be extended to one or more discreet intermediate extended positions. In such embodiments, extendable shaft  124  and hand piece  114  may include cooperating features (e.g., recesses, protrusions, etc.) that facilitate location of extendable shaft in the one or more discreet intermediate extended positions. In other embodiments, the one or more intermediate positions may not be discreet positions. Rather, extendable shaft  124  can be extended to substantially any position between the extended and retracted positions shown in  FIGS. 2 and 3 . 
     Extendable shaft  124  can also include a channel or conduit  126  extending therethrough. As discussed elsewhere herein, conduit  126  can be used to convey fluids through instrument  104 . For example, smoke or other fluids at a surgical site can be evacuated through conduit  126 . In other embodiments, fluids (e.g., water, saline, etc.) may be delivered to a target site through conduit  126 . 
     In the illustrated embodiment, electrode tip  116  is received partially within the distal end of the extendable shaft  124 . A portion of electrode tip  116  extends from the distal end of shaft  124  so as to be able to interact with patient tissue during an electrosurgical procedure. As can be seen in  FIGS. 2 and 3 , electrode tip  116  is mounted within the distal end of shaft  124  such that electrode tip  116  moves with shaft  124  as shaft  124  is moved between the retracted and extended positions. 
     In some embodiments, such as that shown in  FIGS. 2 and 3 , the distal end of shaft  124  may be transparent or semi-transparent. For instance, the distal end of shaft  124  may comprise a nozzle  128  formed of a transparent or semi-transparent material. In other embodiments, more than just the distal end of shaft  124  can be transparent or semi-transparent. Making at least the distal end of shaft  124  transparent or semi-transparent can provide a surgeon with an increased field of view when using instrument  104 . For instance, the transparent or semi-transparent portion of shaft  124  may allow a surgeon to see the portion of the surgical field on the opposite side of the shaft  124  without requiring the surgeon to move the instrument  104 . 
     As illustrated in  FIGS. 2 and 3 , hand piece  114  includes a receptacle  130  at proximal end  120 . Alternative embodiments can include a receptacle on a top and/or side section of a hand piece and/or at different locations along the length of the hand piece (i.e., between the proximal and distal ends thereof). Receptacle  130  can be configured to have utility conduit  108  (or vacuum hose  112  thereof) ( FIG. 1 ) connected thereto. Receptacle  130  can also be configured to have cable  110  ( FIG. 1 ) extend therethrough. In some embodiments, including the illustrated embodiment, receptacle  130  can have an angled configuration. In other embodiments, receptacle  130  can have a straight configuration. Furthermore, in some embodiments, receptacle  130  can be connected to hand piece  114  in a fixed manner. In other embodiments, receptacle  130  can be rotatably or pivotally connected to hand piece  114  such that hand piece  114  can rotate or pivot relative to receptacle  130  and utility conduit  108  or vice versa. 
     Regardless of the specific configuration of receptacle  130 , utility conduit  108  (or cable  110  or vacuum hose  112  thereof) can be connected to instrument  104  to provide instrument  104  with certain capabilities or functionality. As noted above, for instance, cable  110  can communicate electrical energy from generator  102  to instrument  104 . The electrical energy can be communicated through instrument  104  to electrode tip  116  during an electrosurgical procedure. When vacuum hose  112  is connected to instrument  104 , instrument  104  can be used to evacuate smoke/fluid away from a surgical site through conduit  126 , hand piece  114 , and vacuum hose  112 . 
     The operation of instrument  104  can be controlled at least partially with one or more controls  132  on hand piece  114 . The one or more controls  132  enable a user to adjust one or more parameters of the instrument  104 , such as increasing or decreasing electrical power delivery through the instrument, turning the instrument on and off, adjusting the instrument for different operating modes (cut, coagulate, cut-coagulate blend), activating a vacuum, etc. For example, the controls  132  can provide a connection for transmitting control signals from the instrument  104  to generator  102  and/or a vacuum unit. 
     Instrument  104  also includes a locking mechanism  134 . As will be discussed in greater detail below, locking mechanism  134  can be used to selectively secure shaft  124  is a desired position relative to hand piece  114 . Additionally, locking mechanism  134  can also be selectively loosened to allow shaft  124  to be repositioned relative to hand piece  114 . Furthermore, locking mechanism  134  can also secure shaft  124  to hand piece  114  such that shaft  124  cannot be inadvertently removed entirely from hand piece  114 . 
     Attention is now directed to  FIG. 4 , which illustrates a cross-sectional view of instrument  104 .  FIG. 4  illustrates the extendable shaft  124  in a retracted position, showing that much of the extendable shaft  124  can be positioned within an interior chamber or conduit  136  of hand piece  114 . In the illustrated embodiment, interior conduit  136  is configured in size and shape to enclose extendable shaft  124  (e.g., at least the portions not extending distally beyond hand piece  114 ) so that extendable shaft  124  fits within interior conduit  136  and is selectively translatable within interior conduit  136 . As shown, interior conduit  136  is in fluid communication with the atmosphere exterior to hand piece  114  via conduit  126  in shaft  124 , enabling the capture of smoke into interior conduit  136  through conduit  126 . 
     In some embodiments, instrument  104  includes a back stop  138  positioned to limit proximal translation of extendable section  124  within interior conduit  136 . For example, back stop  138  can be disposed at a position such that when extendable shaft  124  is fully retracted, at least nozzle  128  and/or electrode tip  116  is at or near the distal portion of hand piece  114  but not retracted into the interior of the hand piece  114 . 
     The illustrated back stop  138  is formed as part of receptacle  130  to prevent proximal movement of extendable shaft  124  past back stop  138 . Alternatively, back stop  138  can be formed as a crossbar, wall, rib, detent, abutment, catch, brace, and/or other mechanisms of limiting proximal movement of shaft  124 . 
     In the illustrated embodiment, shaft  124  includes a collet  140  disposed therein near the distal end of shaft  124 . Collet  140  is configured to have a portion (e.g., a shaft or shank) of electrode tip  116  mounted therein. With electrode tip  116  mounted in collet  140 , a portion of electrode tip  116  extends distally from shaft  124  as shown so that electrode tip  116  can interact with patient tissue. 
     In some embodiments, such as the illustrated embodiment, collet  140  and/or electrode tip  116  are electrically connected to hand piece  114  by way of a sliding electrical connection. More specifically, hand piece  114  includes a conductor  142  disposed on an interior surface of interior conduit  136 . Similarly, extendable shaft  124  includes a sliding conductor  144 . Sliding conductor  144  is in electrical contact with conductor  142  and collet  140  and/or electrode tip  116 . 
     Conductor  142  is electrically connected to cable  110  ( FIG. 1 ). Accordingly, electrical energy communicated to instrument  104  via cable  110  can be communicated to conductor  142 . Electrical energy communicated to conductor  142  is in turn communicated to collet  140  and/or electrode tip  116 . The electrical connection between conductors  142 ,  144  can be maintained even when shaft  124  is moved between the retracted and extended positions. In particular, as shaft  124  is moved between the retracted and extended positions, sliding conductor  144  moves with shaft  124  and slides along conductor  142  to maintain the electrical connection therebetween. As a result electrical energy can be communicated from cable  110  to electrode tip  116  through the continuous connection between conductors  142 ,  144 . 
     In some embodiments, sliding conductor  144  can be replaced with other electrical connections to hand piece  114 . For instance, extendable shaft  124  may be electrically conductive and able to pass electrical current to electrode tip  116 . For example, electrical energy can be communicated from cable  110  to conductor  142  and then from conductor  142  to electrically conductive shaft  124  and to electrode tip  116  (directly or through collet  140 ). In such embodiments, extendable shaft  124  may be formed from a conductive material that is at least partially coated with a non-conductive material to prevent the transfer of current from extendable shaft  124  to patient tissue during an electrosurgical procedure. 
     Alternatively, hand piece  114  and shaft  124  (or collet  140  or electrode tip  116 ) can be electrically connected with a flexible electrical ribbon to allows shaft  124  to move between the retracted and extended positions while maintaining electrical contact between hand piece  114  and shaft  124  (or collet  140  or electrode tip  116 ). In still other embodiments, cable  110  can extend into hand piece  114  and connect directly to shaft  124 , conductor  144 , collet  140 , or electrode tip  116 . 
     As shown, extendable shaft  124  can be formed with a length (measured along the proximal-distal axis) to be about the same length (e.g., within 99% of, 95% of, 90% of, 80% of, or 75%) of hand piece  114  in which it can selectively translate within. In other embodiments, extendable shaft  124  may be shorter or longer, such as about 0.75 times or 0.5 times the length of hand piece  114 , or about 1.25, 1.5, 2, or 2.5 times longer than the length of hand piece  114 . 
     As noted above and as can be seen in  FIG. 4 , extendable shaft  124  includes conduit  126  extending therethrough. Shaft  124  is configured to pass at least partially into interior conduit  136  of hand piece  114  such that conduit  126  is in fluid communication with conduit  136  and utility conduit  108  (and/or with vacuum hose  112  thereof). Extendable shaft  124  also includes a distal end opening  146  providing fluid communication between conduit  126  and the atmosphere exterior to extendable shaft  124 . As shown, electrode tip  116  can be coupled to extendable shaft  124  (e.g., via collet  140  or other mechanisms (adhesive, welding, mechanical fastening, notches, slots, and/or friction fitting, or through integral formation of a single piece)) in a manner that leaves one or more aperture spaces for smoke capture into conduit  126  of extendable shaft  124 . 
       FIG. 5  illustrates instrument  104  with extendable shaft  124  in an extended position. As can be seen, sliding conductor  144  remains in electrical contact with conductor  142  so that electrical energy can be communicated to electrode tip  116 . Additionally, smoke or other fluids can be evacuated through conduits  126 ,  136  in shaft  124  and hand piece  114  and out through utility conduit  108  (or vacuum hose  112 ). 
     Attention is now directed to  FIGS. 6-10 , which illustrate locking mechanism  134  in greater detail. As noted above, locking mechanism  134  can selectively secure shaft  124  in a desired position relative to hand piece  114 . For instance, locking mechanism  134  can selectively secure shaft  124  in the retracted position (see  FIGS. 2 and 4 ), in the extended position (see  FIGS. 3 and 5 ), or in one or more intermediate extended positions. Additionally, locking mechanism  134  can be selectively unlocked, disengaged, or loosened to enable shaft  124  to move between the retracted and extended positions. 
       FIG. 6  illustrates locking mechanism  134  in a locked, engaged, or tightened configuration. When locking mechanism  134  is in the locked, engaged, or tightened configuration, shaft  124  is secured in place relative to hand piece  114 . In the illustrated embodiment, locking mechanism  134  is in the locked, engaged, or tightened configuration when a locking nut  148  is rotated (e.g., about shaft  124 ) so that locking nut  148  is moved proximally relative to hand piece  114 . 
     In contrast,  FIG. 7  illustrates locking mechanism  134  in an unlocked, disengaged, or loosened configuration. When locking mechanism  134  is in the unlocked, disengaged, or loosened configuration, shaft  124  is able to move relative to hand piece  114  between the retracted and extended positions. In the illustrated embodiment, locking mechanism  134  is in the unlocked, disengaged, or loosened configuration when locking nut  148  is rotated (e.g., about shaft  124 ) so that locking nut  148  is moved distally relative to hand piece  114 . 
       FIGS. 8-12  illustrate various views of locking mechanism  134 . In particular,  FIGS. 8 and 9  illustrate the distal end of instrument  104  with locking nut  148  disconnected from hand piece  114  to show interior features of locking mechanism  134 . Similarly,  FIGS. 10A-10B  illustrate the distal end of instrument  104  with locking nut  148  disconnected from hand piece  114  and shown in shown in cross-section.  FIGS. 11 and 12  show the distal end of instrument  104  in cross-section, with the locking mechanism  134  in the unlocked ( FIG. 11 ) and locked ( FIG. 12 ) configurations. 
     In the illustrated embodiment, locking nut  148  can slide over the distal end of shaft  124  (e.g., such that shaft  124  extends through locking nut  148 ) and can be secured or connected to hand piece  114 . In general, the connection between locking nut  148  and hand piece  114  is achieved by way of mating pins and grooves, aspects of which are illustrated in  FIGS. 8-10B . More specifically, locking nut  148  includes one or more engagement members, such as pins  150  ( FIGS. 9-10A ), spaced about its interior circumference. Pins  150  are configured and arranged to engage hand piece  114 , as discussed below. 
     In correspondence with pins  150 , hand piece  114  includes a collar  152  with one or more grooves  154  formed in an outer surface thereof. The grooves  154  can extend circumferentially around at least a portion of collar  152  and axially along at least a portion of the length of collar  152  (e.g., in the proximal/distal direction). The width and depth of grooves  154  generally correspond to the diameter and length, respectively, of pins  150 . As best illustrated in  FIG. 10A , each groove  154  includes three connected portions, or segments. Specifically, each groove  154  includes an entry segment  156 , an intermediate segment  158 , and a terminal segment  160 . In some alternative embodiments, grooves  154  are defined by a structure that is discrete from, but attached or attachable to, hand piece  114 . 
     In the illustrated embodiment, entry segment  156  extends proximally from a distal end of collar  152 . In the illustrated embodiment, entry segment  156  is generally parallel with the proximal/distal axis of instrument  104 . In other embodiments, entry segment  156  may extend axially along and circumferentially about collar  152 . 
     In the illustrated embodiment, entry segment  156  also include a retention feature  162 . Retention feature  162  may be configured to allow pin  150  to enter into groove  154  while restricting or preventing removal of pin  150  from groove  154 . For instance, retention feature  162  may include an angled surface that allows pin  150  to slide over retention feature  162  as pin  150  is introduced into groove  154 . Opposite the angled surface, retention feature  162  may include a retention wall that restricts or prevents pin  150  from being removed from groove  154 . 
     Intermediate segment  158  is connected to entry segment  156  and extends proximally and circumferentially from entry segment  156 . That is, intermediate segment  158  extends axially along and circumferentially about collar  152 . As noted below, the angled orientation of intermediate segment  158  causes locking nut  148  to move axially relative to hand piece  114 . 
     Terminal segment  160  is connected to intermediate segment  158 . As can be seen in  FIG. 10A , at least a portion of terminal segment  160  extends distally and in a direction generally parallel to the proximal/distal axis of instrument  104 . In other embodiments, terminal segment  160  extends axially and circumferentially such that terminal segment  160  and intermediate segment  158  form an acute angle. In either case, a retention ridge  164  is formed between intermediate and terminal segments  158 ,  160 . Retention ridge  164  is configured to selectively maintain pin  150  in terminal segment  160 , thereby preventing locking nut  148  from being inadvertently loosened. 
     In general, the engagement of locking nut  148  and hand piece  114  is effected by positioning each pin  150  in a corresponding groove  154  and causing pins  150  to travel along or through grooves  154 . More particularly, locking nut  148  and hand piece  114  are brought together until each pin  150  is positioned in the entry segment  156  of a corresponding groove  150  of hand piece  114 . Locking nut  148  is then advanced proximally until pins  150  pass over retention features  162  in entry segments  156 . When locking nut  148  is so positioned (e.g., with pins  150  in entry segments  156  proximal to retention feature  162 ), locking mechanism  134  is in the unlocked, disengaged, or loosened configuration as shown in  FIG. 7 . 
     Rotation of locking nut  148  (e.g., about shaft  124  or collar  152 ) is then initiated. As a result of the angular orientation of intermediate segments  158  with respect to a longitudinal (proximal/distal) axis of instrument  104 , the rotation of locking nut  148  causes locking nut  148  to be drawn proximally towards hand piece  114 . Continued rotation of locking nut  148  causes pins  150  to travel past retention ridges  164  and into the terminal segments  160 . When locking nut  148  is rotated so pins  150  are positioned in terminal segments  160 , locking mechanism  134  is in the locked, engaged, or tightened position as shown in  FIG. 6 . 
     To put the locking mechanism  134  in the unlocked, disengaged, or loosened position, locking nut  148  is moved proximally relative to hand piece  114  so as to allow pins  150  to pass over retention ridges  164 . Locking nut  148  is then rotated so that pins  150  pass back through intermediate segments  158  and to entry segments  156 . As will be appreciated, the angular configuration of intermediate segments  158  causes locking nut  148  to move distally relative to hand piece  114 . As noted above, retention features  162  can also restrict or prevent pins  150  from exiting grooves  154 , thereby restricting or preventing locking nut  148  from being completely disconnected from hand piece  114  when locking nut  148  is moved to the unlocked position. 
     It will be appreciated that the specific configuration and arrangement of the locking mechanism  134  and features thereof as shown in  FIGS. 8-10A  is illustrative only. For instance,  FIG. 10B  illustrates a locking mechanism  134 A that includes elements that are similar to those of locking mechanism  134 , but in a different configuration or arrangement. In particular, the position of the engagement members or pins and the grooves are reversed. Accordingly, instead of engagement members or pins being disposed on an interior surface a locking nut, the collar  152 A includes one or more engagement members or pins  150 A disposed on an exterior surface thereof. Similarly, instead of grooves being forming in an exterior surface of a collar, one or more grooves  154 A are formed on an interior surface of locking nut  148 A. 
     In the embodiment illustrated in  FIG. 10B , locking nut  148 A can slide over the distal end of shaft  124  (e.g., such that shaft  124  extends through locking nut  148 A) and can be secured or connected to hand piece  114 . In general, the connection between locking nut  148 A and hand piece  114  is achieved by in a manner similar to that described above in connection with  FIG. 10A . That is, the pins  150 A can be inserted and advanced through the grooves  154 A. 
     In contrast to groove  154  of  FIG. 10A , groove  154 A includes: (i) an entry segment  156 A extends distally from a proximal end of locking nut  148 A, (ii) an intermediate segment  158 A connected to entry segment  156 A and that extends distally and circumferentially from entry segment  156 A, and (iii) a terminal segment  160 A connected to intermediate segment  158 A. As can be seen in  FIG. 10B , at least a portion of terminal segment  160 A extends proximally and in a direction generally parallel to the proximal/distal axis of instrument  104  such that a retention ridge  164 A is formed between intermediate and terminal segments  158 A,  160 A. 
     In general, the engagement of locking nut  148 A and hand piece  114  is effected by positioning each pin  150 A in a corresponding groove  154 A and causing pins  150 A to travel along or through grooves  154 A or grooves  154 A to moves over pins  150   a . More particularly, locking nut  148 A and hand piece  114  are brought together until each pin  150 A is positioned in the entry segment  156 A of a corresponding groove  150 A of in locking nut  148 A. Locking nut  148  is then advanced proximally until pins  150  pass over retention feature  162 A in entry segments  156 A. When locking nut  148 A is so positioned (e.g., with pins  150 A in entry segments  156 A distal to retention feature  162 A), locking mechanism  134 A is in the unlocked, disengaged, or loosened configuration as shown in  FIG. 7 . 
     Rotation of locking nut  148 A (e.g., about shaft  124  or collar  152 ) is then initiated. As a result of the angular orientation of intermediate segments  158 A with respect to a longitudinal (proximal/distal) axis of instrument  104 , the rotation of locking nut  148 A causes locking nut  148 A to be drawn proximally towards hand piece  114 . Continued rotation of locking nut  148 A causes pins  150 A to travel past retention ridges  164 A and into the terminal segments  160 A. When locking nut  148 A is rotated so pins  150 A are positioned in terminal segments  160 A, locking mechanism  134 A is in the locked, engaged, or tightened position as shown in  FIG. 6 . 
     To put the locking mechanism  134 A in the unlocked, disengaged, or loosened position, locking nut  148 A is moved proximally relative to hand piece  114  so as to allow pins  150 A to pass over retention ridges  164 A. Locking nut  148 A is then rotated so that pins  150 A pass back through intermediate segments  158 A and to entry segments  156 A. As will be appreciated, the angular configuration of intermediate segments  158 A causes locking nut  148 A to move distally relative to hand piece  114 . As noted above, retention features  162 A can also restrict or prevent pins  150 A from exiting grooves  154 A, thereby restricting or preventing locking nut  148 A from being completely disconnected from hand piece  114  when locking nut  148 A is moved to the unlocked position. 
     As the locking nut moves between the locked position ( FIGS. 6 and 12 ) and the unlocked position ( FIGS. 7 and 11 ), the locking nut interacts with compression flanges  166  to either secure shaft  124  in place or allow shaft  124  to move between the retracted and extended positions. As can be seen in  FIGS. 8-10B , compression flanges  166  extend distally from collar  152  and are disposed circumferentially about shaft  124 . Additionally, compression flanges  166  are spaced apart from one another such that a gap  168  is disposed between adjacent flanges  166 . The gaps  168  between compression flanges  166  allow compression flanges  166  to be compressed or flexed inward towards shaft  124  as the locking nut moves from the unlocked position to the locked position. 
     As can be seen in  FIGS. 9-12 , locking nuts  148 ,  148 A include a tapered interior surface  170 . Surface  170  tapers in the distal direction such that surface  170  has a larger diameter at a proximal end than at a distal end. Tapered surface  170  interacts with compression flanges  166  to secure shaft  124  in place or to allow shaft  124  to move between the retracted and extended positions. 
     As can be seen in  FIG. 11 , when locking nut  148  is in the unlocked position (e.g., moved distally relative to hand piece  114  so that pins  150  are in or near the entry segments  156 ), the angled configuration of tapered surface  170  allows compression flanges  166  to flex away from shaft  124 . As a result, the friction between compression flanges  166  and shaft  124  is reduced or eliminated, thereby allowing shaft  124  to move between the retracted and extended positions. 
     In contrast, as shown in  FIG. 12 , when locking nut  148  is moved to the locked position (e.g., moved proximally relative to hand piece  114  so that pins  150  are in or near the terminal segments  160 ), tapered surface  170  interacts with compression flanges  166  to flex or compress compression flanges  166  towards shaft  124 . Tapered surface  170  can flex or compress compression flanges  166  against shaft  124  with sufficient force to secure shaft  124  in place. As a result, shaft  124  can be selectively maintained in a desired position (e.g., retracted, intermediate extended, or extended position). 
     As noted above, locking mechanism  134  can also prevent shaft  124  from being inadvertently removed from hand piece  114 . For instance, shaft  124  and locking mechanism  134  can have cooperating features to limit the distal movement of shaft  124  relative to hand piece  114 . In the illustrated embodiment, shaft  124  includes a stop  172  ( FIGS. 4 and 5 ) on an exterior surface thereof adjacent to the proximal end of shaft  124 . Stop  172  can interact with a shoulder  174  ( FIGS. 8-12 ) on locking nut  148  to prevent shaft  124  from being (inadvertently) removed entirely from hand piece  114 . By way of example, if locking mechanism  134  is moved to the unlocked configuration and shaft  124  is moved distally relative to hand piece  114 , stop  172  will engage shoulder  174  prior to shaft  124  being removed entirely from hand piece  114 . Thus, the interaction between stop  172  and shoulder  174  can prevent a surgeon or other personnel from inadvertently removing shaft  124  from hand piece  114  when attempting to adjust the extension of shaft  124  from hand piece  114 . 
     Attention is now directed to  FIG. 13 , which illustrates a locking mechanism  134   b . Locking mechanism  134   b  can be similar or identical to locking mechanism  134  and can be used with an electrosurgical instrument similar or identical to instrument  106  discussed above. For instance, locking mechanism  134   b  includes a collar  152   b  adjacent a distal end of a hand piece  114   b . One or more grooves  154   b  may be disposed in collar  152   b , similar or identical to grooves  154 , for securing a locking nut (e.g., locking nut  148 ) to collar  152   b  in a similar manner as described above. 
     One distinction between locking mechanism  134   b  and locking mechanism  134  is that compression flanges  166   b  are not integrally formed with collar  152   b  or hand piece  114   b . Rather, as illustrated in  FIG. 13 , compression flanges  166   b  (separated by gaps  168   b ) are connected to or integrally formed with a ring  180 . Ring  180  is configured to be selectively connected to the distal end of collar  152   b  or hand piece  114   b . Such connection can take a variety of forms. In the illustrated embodiment, for instance, ring  180  can be connected to collar  152   b  or hand piece  114   b  via a snap-fit connection. By way of example, an annular groove  182  is formed on an outer surface of the distal end of collar  152   b  or hand piece  114   b . Ring  180  includes one or more corresponding detents  184  disposed on a proximal interior surface. Ring  180  can be connected to collar  152   b  or hand piece  114   b  by snapping detent(s)  184  into groove  182 . 
     In some embodiments, ring  180  can provide a similar function as shoulder  174  described above. More specifically, ring  180  can prevent an extendable shaft (e.g., similar to shaft  124 ) from being inadvertently removed from hand piece  114   b . As noted above in connection with shaft  124 , an extendable shaft can include a stop (e.g., stop  172 ) on an exterior surface thereof. The stop can interact with ring  180  to prevent the shaft from being (inadvertently) removed entirely from hand piece  114   b . By way of example, if locking mechanism  134   b  is moved to the unlocked configuration and an extendable shaft is moved distally relative to hand piece  114   b , the stop will engage ring  180  prior to the shaft being removed entirely from hand piece  114   b . Thus, the interaction between the stop and ring  180  can prevent a surgeon or other personnel from inadvertently removing the shaft from hand piece  114   b  when attempting to adjust the extension of the shaft from hand piece  114   b.    
     Additionally, the ring  180  can be coupled to collar  152   b  or hand piece  114   b  so as to close off or block an open end of a track  186  formed on the interior of hand piece  114   b . The track  186  may be configured to have the stop (e.g., stop  172 ) on the extendable shaft move therethrough as the extendable shaft is moved between extended and retracted positions. The open end of the track  186  shown in  FIG. 13  may enable the stop to be inserted into the track  186 , thereby allowing the extendable shaft to be inserted into the hand piece  114 . Once the extendable shaft is inserted into the hand piece  114   b  and ring  18  is connect thereto, ring  180  can prevent the stop on the extendable shaft from exiting the end of the track  186 . Retaining the stop in the track  186  can prevent undesirable rotation of the extendable shaft within hand piece  114   b.    
     Attention is now directed to  FIGS. 14-17  which illustrate another example of a locking mechanism according to the present disclosure. Rather than having compression flanges (e.g.,  166 ,  166   b ) integrally formed with or connected to a collar (e.g.,  152 ,  152   b ) or a hand piece ( 114 ,  114   b ), the illustrated embodiment includes compression flanges  166   c  integrally formed as part of or connected to a locking nut  148   c .  FIGS. 14 and 15  illustrate an end perspective view and a cross-sectional view of locking nut  148   c . As can be seen, the compression flanges  166   c  extend proximally from an interior surface of locking nut  148   c  as are separated by gaps  168   c.    
     When locking nut  148   c  is connected to collar  152   c /hand piece  114   c  as shown in  FIGS. 16 and 17 , the compression flanges  166   c  extend proximally towards hand piece  114   c . Additionally, the proximal ends of compression flanges  116   c  can extend into the distal end of collar  152   c /hand piece  114   c  between the extendable shaft  124   a  and the distal end of collar  152   c /hand piece  114   c . When the locking nut  148   c  is in the locked position as shown in  FIG. 16 , the compression flanges extend deeper into collar  152   c /hand piece  114   c . As the compression flanges  166   c  extend deeper into collar  152   c /hand piece  114   c , the interior surface of collar  152   c /hand piece  114   c  causes the compression flanges  166   c  to flex towards shaft  124   a . As the compression flanges  166   c  flex towards shaft  124   a , the friction between the compression flanges  166   c  and the shaft  124   a  increases sufficiently to secure the shaft  124   a  in place. 
     In contrast, when the locking nut  148   c  is in the unlocked position as shown in  FIG. 17 , the compression flanges are withdrawn at least partially from collar  152   c /hand piece  114   c . As the compression flanges  166   c  are withdrawn from collar  152   c /hand piece  114   c , the interior surface of collar  152   c /hand piece  114   c  causes the compression flanges  166   c  to flex towards shaft  124   a  to a lesser degree compared to when the locking nut  148   c  is in the locked position. As a result, the friction between the compression flanges  166   c  and the shaft  124   a  is reduced sufficiently to allow the shaft  124   a  to move between the extended and retracted positions. 
     While the embodiments described herein have been directed to electrosurgical instruments with smoke evacuation features, the present disclosure is not intended to be so limited. Rather, the present disclosure is broadly directed to any instrument, hand-held or not, that includes an extendable shaft. The extendable shaft may increase the reach of the instrument and/or provide fluid evacuation or delivery capabilities. By way of non-limiting example, such instruments may include dental instruments (e.g., drills, polishing tools, scalers, compressed air tools, suction tools, irrigation tools, carries detection tools, water flossing tool (e.g., waterpik)), soldering tools (e.g., heated tools, smoke collection tools, de-soldering tools), high speed grinding and polishing tools (e.g., Dremel tools, carving tools, manicure tools, dental lab grinders/polishers), laser treatment instruments, laser surgical instruments, light probes, suction handles (e.g., Yankauer), blasting tools (e.g., sandblast, gritblast), shockwave therapy tools, ultrasonic therapy tools, ultrasonic probe tools, ultrasonic surgical tools, adhesive application instruments, glue guns, pneumatic pipettes, welding tools, RF wrinkle therapy devices, phaco devices, shears, shaver, or razor devices, micro drill devices, vacuum devices, small parts handling devices, tattoo needle handles, small torch devices, electrology devices, low speed grinding, polishing and carving tools, permanent makeup devices, electrical probe devices, ferromagnetic surgical devices, surgical plasma devices, argon beam surgical devices, surgical laser devices, surgical suction instruments (e.g., liposuction cannulas), surgical suction cannulas, microdermabrasion devices, fiberoptic cameras, microcamera devices, pH probe devices, fiberoptic and LED light source devices, hydrosurgery devices, orthopedic shaver, cutter, burr devices, wood burning tools, electric screwdrivers, electronic pad styluses, and the like. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.