Patent Publication Number: US-2007112377-A1

Title: Reusable laparoscopic surgical instrument

Description:
RELATED APPLICATIONS  
      This patent application claims priority and the benefit under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 60/734,827, filed Nov. 9, 2005, which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates generally to the field of surgical instruments, such as laparoscopic instruments. More specifically, the present invention relates to a reusable hand held laparoscopic surgical instrument that prevents the infiltration of C 0 2 through the instrument during the surgical procedure while having improved flushing, decontamination, cleaning, sterilization, and post-sterilization moisture elimination capabilities. The present invention also has an improved construction that helps prevent the collection of bio-burden on the outside portion of the instrument and an improved insulating material(s) to reduce the risk of a patient burn.  
     BACKGROUND OF THE INVENTION  
      The use of surgical instruments such as laparoscopic instruments for doing minimally invasive surgical procedures is known. A major consideration with the use of these reusable laparoscopic instruments is the protection of patients&#39; from a deep organ surgical site infection (SSI) caused by residual bio-burden and/or waterborne pathogens that remain inside the lumen of the instrument after reprocessing. “The Centers for Disease Control and Prevention (CDC) reports that hospital acquired infections (HAI&#39;s) cause 90,000-plus patients to die of the total two million that contact these infections annually. This mortality figure is more than the combined total number of deaths attributed to AIDS, breast cancer and motor vehicle accidents.” (Thomas L. Kovach, Infection Control Today, June 2005).  
      Surgical infections account for nearly one-third of all HAI&#39;s, or over 667,000 annually in the United States. Approximately one-half of all surgical procedures done in the U.S. are performed laparoscopically and account for over 333,000 surgical infections and over 15,000 patient deaths annually. Any and all steps taken to reduce the risk of an SSI caused by a reusable laparoscopic instrument contaminated by bio-burden and/or waterborne pathogens that remain inside the lumen of the instrument after sterile reprocessing will have an immediate, positive impact on reducing the risk of an SSI and will contribute to improved patient outcomes.  
      The goal of laparoscopic instrument reprocessing is to ensure a decontaminated, clean, sterile, and moisture-free instrument for every laparoscopic surgical procedure. There are three main elements in instrument reprocessing that must be accomplished every time in order to achieve this goal. First, the instrument must be designed so that the reprocessing technician can remove bio-buren from inside the lumen of the instrument and the outside housing of the instrument prior to the sterilization cycle. Second, the instrument must be designed to ensure 100% bacteria kill on every sterilization cycle. Third, the instrument must be designed to be “moisture free” after every sterilization cycle in order to eliminate the risk of contamination caused by the presence of waterborne pathogens trapped inside the lumen.  
      An important problem associated with the use of reusable laparoscopic instruments is the removal of the bio-burden and microorganisms that collect inside the lumen of the instrument. During a surgical procedure, the distal end of the instrument is placed inside the patient and the lumen comes into contact with the patient&#39;s bio-burden (blood, microorganisms, protein, fat, starches and carbohydrates). In order to provide adequate visualization during a laparoscopic procedure, the patient&#39;s abdominal cavity is insufflated with C 0 2 gas to two times the normal atmospheric pressure. During a laparoscopic procedure, some of the pressurized C 0 2 gas escapes through both the luer port on the handle and through the opening for the operating rod in the handle. As the high pressure C 0 2 escapes through the instrument, it pulls some of the patient&#39;s bio-burden into the instrument, coating the wall of the lumen and the operating rod. Once inside the lumen of the instrument and on the operating rod, the bio-burden is difficult, if not impossible, to remove during cleaning and decontamination.  
      In the April 2001 AORN Journal, Romona Conner states, “[d]econtamination is the first and most important step in the sterilization process. Inadequate cleaning of organic debris (bio-burden) may result in retained organisms and make the sterilization process ineffective.” In the June 2002 issue of Infection Control Today, Kelly M. Pyrek states, “[i]nadequate cleaning has the potential to allow for residual bio-burden to be sequestered in bodily fluids that may be contaminated with gram-negative bacteria. You can sterilize it but you may fail to destroy microbial endotoxins that are heat-stable. So cleaning is an absolutely crucial step before any terminal disinfection or sterilization process.” 
      In the CDC&#39;s report Guideline for the Prevention of Surgical Site Infection, 1999 the authors state, “[a]mong surgical patients, SSI&#39;s (surgical site infections) were the most common infection, accounting for 38% of all such infections. Of these SSI&#39;s, two-thirds were confined to the incision, and one-third involved organs or spaces accessed during the operation. When surgical patients with SSI&#39;s died, 77% of the deaths were reported to be related to the infection, and the majority (93%) were serious infections involving organs or spaces accessed during the operation.” 
      During a surgical laparoscopic procedure, nothing comes in contact more frequently with the organs or spaces accessed during the operation more than the laparoscopic instruments. In the article Infection Control Challenges With Laparoscopic Instruments (Infection Control Today, November 2002) author Ann Hewitt, RN, BSN, MM, states, “[r]eusable laparoscopic instruments that are not (or cannot be) properly cleaned and sterilized are a major cause of deep organ SSI&#39;s. The CDC notes ‘Inadequate sterilization of surgical instruments has resulted in SSI outbreaks’ and cites articles in Anesthesiology, MMWR and Journal of Hospital Infections in asserting this claim.” Hewitt goes on to point out that “[d]ue to the design of internal lumens and channels in many laparoscopic instruments, it is impossible to access the entire surface area that needs cleaning. Squared off comers, dead spaces and rough edges all provide nooks and crannies for the deposit of tissue, blood, mucous or other bio-burden. Devices that you know are damaged, corroded, bent or constructed with inaccessible surfaces that come into contact with patient tissue should not be used on patients.” 
      Another problem caused by the internal design of laparoscopic instruments, both “one-piece” and “take-a-part”, is that it is difficult, if not impossible, to remove residual moisture from inside the lumen of the instrument after the sterilization cycle. Residual moisture has the potential to colonize and grow waterborne pathogens inside the lumen of the instrument. Waterborne pathogens have been documented to be a significant cause of hospital acquired infections (HAI&#39;s). Although a skilled technician can remove bio-burden from the lumen of a “take-a-part” laparoscopic instrument, once it has been re-assembled and sterilized, it is very difficult to remove the residual moisture that becomes trapped inside the instrument during sterilization. The presence of waterborne pathogens trapped inside the lumen of an instrument has the potential to cause a deep organ surgical infection, despite the instrument having gone through the cleaning and sterilization process.  
      Another problem with conventional reusable laparoscopic instruments is that this outer housing or shaft has always been made out of stainless steel with a wall thickness of  1 mm or less, resulting in a lot of “dead space” within the lumen of the instrument. This excess “dead space” allows for the collection, retention and build-up of infectious bio-burden within the lumen of the shaft thereby reducing the effectiveness of the detergent flush during cleaning.  
      A further issue with some reusable laparoscopic instruments is a problem with the insulation on the external surface of the housing or shaft. In particular, the external housing (starting from the handle and running to the opening for the clevis and jaw) has been covered with a “shrink film” type of insulating film (approximately 0.3-0.5 mm in thickness) to protect the patient from dangerous electrical burns. Insulation materials vary, but no matter the source, all conventional shrink film materials are generally degradable with use.  
      This thin layer of insulation causes two major problems. First, with normal use, it develops “pin holes” and “cracks” that allow electrical current to leak through the compromised insulation and burn the patient&#39;s tissue and internal organs surrounding the targeted surgical site. Because the keyhole of minimally invasive surgery is so small, the surgeon cannot observe such phenomena outside his field of vision. Most injuries caused by insulation failure result in irreversible tissue death. Diagnosis is difficult and often delayed. Complications include perforated organs, permanent disfigurement, and in an estimated 28% of fecal peritonitis cases, even death. Accordingly, it is critical to patient safety that insulation be flawless to prevent escaping current. The Association of periOperative Registered Nurses (AORN) Board of Directors in its Recommended Practices for Electrosurgery advises, “[t]he active electrode instrument should be inspected for damage, including impaired insulation, at the operative field before use.” Replacing damaged insulation requires that the instrument be taken out of service and sent to a skilled repair facility.  
      The second major problem caused by this thin layer of insulation is the gradual collection and retention of infectious bio-burden between the insulation and the stainless steel shaft at the distal end of the instrument. With each reprocessing cycle, the thin insulation is subject to the heat of sterilization (275 degrees F.) thereby causing the stainless steel shaft and insulation to expand slightly. As the instrument cools to room temperature, the stainless steel shaft contracts to its original diameter, however, the “shrink film” insulation does not contract to its original dimension, and thus creating a small gap between the insulation and the shaft. This small gap grows with each reprocessing cycle. As this gap continues to grow in size and in length along the shaft, it serves to collect and retain infectious bio-burden that is difficult, if not impossible to remove during reprocessing and, left in place, can cause a deep organ surgical infection.  
      Instruments that cannot be flushed and cleaned properly cannot be disinfected or sterilized with certainty, and have been documented to cause life threatening deep organ SSI&#39;s. Accordingly, there exists a need for a reusable laparoscopic instrument that prevents the escape of C 0 2 during the surgical procedure and that provides for the efficient flushing, decontamination, cleaning, sterilization, and post-sterilization moisture elimination of the instrument on every reprocessing cycle. There also exists a need for a reusable laparoscopic instrument that has an improved insulation system that solves the problems inherent in conventional “shrink film” insulation systems.  
     SUMMARY OF THE INVENTION  
      The present invention is directed to a surgical instrument that decreases the accessibility of the interior of the instrument to bio-burden while improving the flushing, decontamination, cleaning, sterilization, and post-sterilization moisture elimination of the instrument.  
      According to a first aspect of the invention, a surgical instrument having a handle, an elongated housing and a movable rod is provided. The housing has a proximal end and a distal end. The handle and the housing define an interior passageway. The elongated housing has a diameter substantially larger than a diameter of the interior passageway. A movable rod is located within the passageway. A tool is connected to the rod and extends from the distal end of the elongated housing.  
      According to a second aspect of the invention, a surgical instrument having a handle, an elongated housing and a movable rod is provided. The elongated housing is connected to the handle. The housing has a proximal end and a distal end. The housing and the handle define an interior passageway. A movable rod is located within the passageway of the handle and the housing. The rod passes through a rear portion of the handle and through the passageway. A tool is connected to a distal end of the rod. A seal is connected to the rod and handle adjacent the passageway.  
      According to a third aspect of the invention, a surgical instrument having a handle, an elongated housing and a movable rod is provided. The elongated housing is connected to the handle. The handle and the housing define an interior fluid passageway. A movable rod is located within the fluid passageway of the handle and housing. A port is connected to the handle and is in fluid communication with the interior fluid passageway. A valve is connected to one of the port and the passageway.  
      According to a fourth aspect of the invention, a surgical instrument having a handle, an elongated housing and a movable rod is provided. The housing has a proximal end and a distal end. The handle and the housing define an interior passageway. The housing is formed from a first nonconductive material. A movable rod is located within the passageway. A tool is connected to the rod and extends from the distal end of the elongated housing.  
      The present invention, together with attendant objects and advantages, will be best understood with reference to the detailed description below in connection with the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is an illustration of a laparoscopic instrument in accordance with a first embodiment of the present invention;  
       FIG. 2A  is an enlarged view of a proximal end of the instrument of  FIG. 1  according to one embodiment;  
       FIG. 2B  is an enlarged view of a proximal end of the instrument of  FIG. 1  according to another embodiment illustrating an alternate location of the valve;  
       FIG. 2C  is an enlarged view of a proximal end of the instrument of  FIG. 1  according to a further embodiment illustrating an alternate embodiment of the operating rod and lumen;  
       FIG. 2D  is an enlarged view of a proximal end of the instrument of  FIG. 1  according to a further embodiment illustrating an alternate embodiment with a cap;  
       FIG. 2E  is a view of one alternate embodiment of the cap shown in  FIG. 2D ;  
       FIG. 2F  is a view of a second alternate embodiment of the cap shown in  FIG. 2D ;  
       FIG. 3  is an enlarged view of the port of  FIG. 2A  illustrating the location of the valve;  
       FIG. 4  is an enlarged view of a seal in the proximal end of the instrument as illustrated in  FIG. 2A ;  
       FIG. 5A  is an enlarged view of a distal end of the instrument according to the embodiment of  FIG. 2A  illustrating the rod, throat and tool;  FIG. 5B  is an enlarged view of a distal end of the instrument according to the embodiment of  FIG. 2C  illustrating the rod, throat and tool; and  
       FIG. 6  is an illustration of further embodiment of a laparoscopic instrument in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention is directed to a surgical instrument such as a reusable laparoscopic instrument with a dramatically reduced surface area/volume of the internal lumen or passageway in order to decrease the collection and retention of bio-burden and waterborne pathogens and increase flushing efficiency. The present invention also prevents the escape of C 0 2 from the insufflated abdominal cavity and thereby minimizes the infiltration and collection of bio-burden during the surgical procedure. The present invention also has an internal lumen or passageway that includes a throat portion featuring a “Venturi” type design. The “Venturi” design has advantages including one or more of the following: (a) minimizing the collection of bio-burden during surgery; (b) maximizing the cleaning and flushing efficiency of the instrument during decontamination to remove sequestered bio-burden; (c) maximizing steam penetration throughout the entire internal lumen of the instrument during the sterilization cycle to ensure 100% bacteria kill; and (d) eliminating the collection and retention of moisture both during and after the sterilization process to eliminate the potential for contamination by waterborne pathogens.  
      In one embodiment, the instrument includes the use of a lumen with dramatically reduced surface area/volume. By using a lumen that defines a relatively small surface area, the opportunity of the collection and retention of bio-burden and waterborne pathogens is decreased. In addition, the small surface area of the lumen provides for an increased flushing efficiency.  
      In another embodiment, the instrument includes a housing formed out of a nonconducting medical grade material that has improved durability and insulating properties.  
      The preferred embodiments are described generally in the context of laparoscopic surgical instruments. However, the principles of the invention apply equally well to other types of surgical instruments that have enclosed lumens and come in contact with bio-burden and microorganisms during surgical procedures.  
       FIG. 1  illustrates a laparoscopic surgical instrument  10  in accordance with a first embodiment of the present invention. The instrument  10  includes a handle  12 , a port  14 , an elongated housing  16  and a tool  18 . The handle  12  includes a thumb portion  20  and a finger portion  22 . The thumb portion  20  includes an opening  24  adapted to receive the thumb of a user. The finger portion  22  includes an opening  26  adapted to receive the finger of a user. An electrode post  28  for use in electrosurgery is located on the finger portion  22 .  
      According to one embodiment of the present invention, the elongated housing  16  or shaft may be formed out of a nonconducting medical grade material that has improved durability and insulating properties compared to the use of a conventional “shrink film” insulation covering a stainless steel housing. More specifically, a non-porous, non-ferrous material such as a unidirectional graphite carbon fiber, Radel®, Poly Sulfoam®, Delrin®, high durometer nylon, and various other commercial graphite-fiber composites may be used to construct the housing  16 . These materials will help prevent the formation of holes and cracks that could let electric current leak through the exterior of the instrument and thus cause a patient burn. In addition, these materials will help prevent the collection of bio-burden on the exterior of the instrument. Alternatively, the housing  16  could be formed from conventional materials such as stainless steel or titanium and then insulated using conventional shrink film materials.  
      The thumb portion  20  and the finger portion  22  may be formed from conventional materials such as stainless steel or other metals such as titanium. Other materials such as carbon fiber or plastics such as Delrin™ may also be used. The handle  12  may also include an insulating coating such as nylon or Teflon™ in order to protect the user from electrical current.  
      A pin  30  interconnects the thumb portion  20  and the finger portion  22  and defines a pivot axis for the handle  12 . The thumb portion  20  is movable relative to the finger portion  22 . An operating rod  40  is connected to an upper portion  42  of the thumb portion  20  and movable therewith. As used herein, the term “rod” should be interpreted broadly to include structures having various shapes, in the cross-section, such as round, rectangular or triangular. A ball  44  (shown in phantom lines) is welded to an end of the operating rod  40 . The ball  44  is located within a pocket within the thumb portion  20  in order to secure the operating rod  40  thereto. In operation, as a user pulls backwards on the thumb portion  20 , the operating rod  40  is pushed forward. As a user pushes forward on the thumb portion  20 , the operating rod  40  is pulled backward. The operating rod  40  slides within the lumen or passageway  50  formed in an upper portion  52  of the finger portion  22  of the handle  12 . The sliding action of the operating rod  40  opens and closes the tool  18 .  
      A port  14  is connected to the upper portion  52  of the finger portion  22  of the handle  12 . As best seen in  FIG. 2A , the port  14  includes a luer connector  60  having an upper rim  62  that is secured to an associated syringe or other infusion device used to infuse a cleaning solution into the passageway  50  formed in the upper portion  52  of the finger portion  22  of the handle  12 . The port  14  also includes a collar portion  64 . The port  14  defines a port passageway  66  that connects to the passageway  50 .  
      In the illustrated embodiment, a 1-way valve  68  is located in the port  14 . The valve  68  can include conventional valves such as the duckbill valve illustrated in  FIG. 3 . Other conventional valves such as a flapper valve or ball valve may also be implemented with the present invention. The valve  68  includes two side portions  72  mounted to inner wall  73  of the port  14  in the illustrated embodiment. Two flexible portions  74  seal a portion of the port passageway  66  and the passageway  50 , but allow for the introduction of a cleaning solution through the port  14 . In particular, the valve  68  prevents the escape of C 0 2 through the instrument during a surgical procedure. As a result, the valve  68  helps minimizes the infiltration and collection of bio-burden during the surgical procedure by preventing it from being passed into the instrument with infiltrating C 0 2 . Yet, the port  14  also provides access for conventional cleaning solutions such as enzymatic detergents that may be infused through the port passageway  66  and into the passageway  50  for the cleaning and sterilization processes.  
      An alternate embodiment for the location of the one-way valve  80  is illustrated in  FIG. 2B . The embodiment of  FIG. 2 B  is essentially the same as the embodiment of  FIGS. 1 and 2 A with the exception of the location of the valve  80 . The valve  80  is located in the upper portion  82  of the passageway  50 . The location of the valve  80  has the advantage of being completely contained within the body of the handle, but may create a more complicated manufacturing and assembly process.  
      Referring again to  FIG. 2A , the upper portion  52  of the handle  12  includes a flushing chamber  90  that forms a portion of the passageway  50 . In the rear portion  92  of the flushing chamber  90 , a seal  96  is provided around the operating rod  40  as it passes out of the flushing chamber  90 . With particular reference to  FIG. 4 , the seal  96  includes a channel  100  through which the operating rod  40  passes. The seal  96  is mounted to a rear portion  102  of the upper portion  52  of the finger portion  22  of the handle  12 . In the illustrated embodiment, the seal  96  is threaded into engagement with the rear portion  102 . In one embodiment, the seal  96  is formed from stainless steel and is coated with Teflon™. It should be recognized that other known means of attachment such as adhesives or compression fit materials may be implemented. Also, other materials known to those of ordinary skill in the art may be used to form the seal  96 . The seal  96  forms an enclosure around the operating rod  40  as it exits the flushing chamber  90  to prevent the escape of C 0 2 during the surgical procedure and the infiltration of bio-burden into the lumen of the instrument. In addition, the seal  96  performs an anti-back flush function that helps prevent cleaning solution passing through the flushing chamber  90  from exiting through the rear portion  102  of the handle  12 , thus increasing the pressure of the flush and increasing the flushing efficiency.  
      The flushing chamber  90 , as illustrated in  FIG. 2A , has a significantly larger diameter than the diameter of the housing passageway  11 O. A throat portion  112  interconnects the flushing chamber  90  and the housing passageway  110 . The throat portion  112  has a cornerless and smooth surface with a smoothly or continuously decreasing diameter that creates a “Venturi” type effect for any cleaning solution passing therethrough. In particular, the decrease in volume between the flushing chamber  90  and the somewhat narrow space in the housing passageway  110  causes the cleaning solution passing therethrough to have an increased flow rate and a pressurized laminar flow which is highly effective in removing bio-burden and microorganisms from the instrument during the flushing and cleaning process. This laminar flow design is also very effective in removing residual moisture from the lumen after sterilization thus eliminating the risk of contamination from waterborne pathogens. It is also important to recognize that the diameter of the operating rod  40  is such that it is spaced closely adjacent to the walls that form the housing passageway  110 . The relatively close or tight space between these surfaces has a number of advantages such as increasing the cleaning solution flow rate, increasing the flushing effectiveness and decreasing the area in which bio-burden may accumulate. According to one embodiment, the space between the operating rod  40  and walls that form the housing passageway  110  should be between 0.002-0.010 inches.  
       FIG. 2C  illustrates an alternate embodiment that operates in the same general manner as the embodiment of  FIG. 2A  with the exception of the size and shape of the operating rod  130  and the housing passageway  132 . The operating rod  130  has a substantially increased size or diameter relative to the operating rod  40  of  FIG. 2A . The housing passageway  132  also has a substantially increased diameter relative to the housing passageway  110  of  FIG. 2A . The operating rod  130  includes a throat portion  134  that forms the same “Venturi” type effect for the cleaning solution passing from the flushing chamber  140  and into the housing passageway  132  adjacent the operating rod  130 . As in the earlier embodiment, the operating rod  130  should be sized to be closely adjacent the walls that form the housing passageway  132 .  
       FIG. 2D  illustrates an alternate embodiment similar to the embodiment of  FIG. 2A  with the exception of a cap  142 . The cap  142  is added to the collar portion  64  such that it covers the luer connector  60 . The cap  142  functions similarly to the valve  68  by helping prevent C 0 2 from escaping through the luer connector  60  during a surgical procedure.  
       FIG. 2E  and  FIG. 2F  are alternate embodiments of the cap  142  in  FIG. 2D . Specifically,  FIG. 2E  is an example of a screw-on cap  144 . The screw-on cap  144  is attached over the luer connector  60  by twisting the screw-on cap  144  such that it fastens to the collar portion  64 . For example, the screw-on cap  144  may have threads  145  that correspond to threads in the collar portion  64  allowing the screw-on cap  144  to be screwed onto the collar portion  64 . In a second alternate embodiment,  FIG. 2F  shows an example of a snap-on cap  146 . The snap-on cap  144  is snapped onto the collar portion  64  over the luer connector  60  such that the grooves  147  in the snap-on cap allow it to fit tightly over the luer connector. It should be recognized that other known cap constructions that provide a leak-proof seal with the luer may be implemented with the present invention.  
       FIG. 5A  illustrates the distal end  150  of the housing  16  associated with the embodiment of  FIGS. 1 and 2 A. The end portion  152  of the operating rod  40  passes through the second throat portion  154  and connects to the tool  18 . Again, the throat portion  154  is cornerless and smooth in order to prevent the accumulation of bio-burden. More specifically, as known in the art, the end portion  152  of the operating rod  40  is connected to the tool  18  at the hinge  160 . As also recognized in the art, the tool  18  can take a wide variety of forms such as a grasping forcep, a curved dissecting forcep, a curved Maryland dissector, a Babcock grasping forcep and other related tools.  
      The operating rod  40  can be formed from conventional metals with stainless steel being the preferred material. In the preferred embodiment, the operating rod  40  and the passageway  50  are superfinished to meet an ANSI B46 standard of 2-8 microinches of roughness. The operating rod  40  and passageway can then be plated with materials such as gold, chrome or nickel with gold being the most preferred material. The use of superfinishing and a plating material creates a very smooth surface to which it is more difficult for bio-burden to attach. In addition, such a surface is more readily flushed, cleaned and sterilized.  
       FIG. 5 B  illustrates the distal end  170  of the instrument associated with the embodiment of  FIG. 2C  and operates in essentially the same manner as the embodiment of  FIG. 1  and  2 A. The end portion  172  of the operating rod  130  passes through the second throat portion  174  and connects to the tool  18 .  
       FIG. 6  illustrates a further embodiment of a laparoscopic instrument  200  in accordance with the present invention. The laparoscopic instrument  200  is constructed in essentially the same manner as the instrument  10  with exception of the construction of the housing  216 . The instrument  200  includes a handle  212 , a port  214 , an elongated housing  216  and a tool  218 . The elongated housing  216  is formed of at least two materials. The inner portion  222  is formed from a stainless steel material and has a relatively thin thickness. The outer portion  224  is formed from a nonconducting material as described with reference to the housing  16  of  FIG. 1  and is relatively thick.  
      The embodiments described above and shown herein are illustrative and not restrictive. The scope of the invention is indicated by the claims rather than by the foregoing description and attached drawings. The invention may be embodied in other specific forms without departing from the spirit of the invention. For example, the type and size of the instrument and portions of the instrument such as the operating rod may be designed in a manner other than as specifically illustrated in the figures. Accordingly, these and any other changes which come within the scope of the claims are intended to be embraced herein.