Patent Abstract:
An endoscopic scissor instrument includes an elongate hollow member having a proximal end and a distal end, an actuator that moves axially through the hollow member, and first and second scissor blades with respective cutting surfaces. At least one of the first and second scissor blades are rotatably coupled to the hollow member adjacent its distal end. At least one of the first and second scissor blades includes a base supporting a resilient leaf-spring portion that includes a respective cutting edge. The resilient leaf-spring portion extends from the base in a cantilevered arrangement along the length of the leaf-spring portion. The cantilevered arrangement of said leaf-spring portion generates a spring force acting on said respective cutting edge such that in a loaded state there is an automatic preload force imparted between the cutting edges of the scissor blades to maintain a consistent and continuous mating force between the two opposed sharpened cutting edges preferably over the complete range of rotational movement of the scissor blades.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to surgical scissors instruments and, more particularly, to endoscopic scissor instruments having small-sized scissor blades. 
         [0003]    2. State of the Art 
         [0004]    Endoscopy is a minimally invasive diagnostic medical procedure that is used to assess the interior of the human body using an endoscope. An endoscope generally consists of a rigid or flexible tube, an fiber optic illumination system to guide light provided by a light source through the tube of the endoscope in order to illuminate the organ or object under inspection, and a viewing system for collecting an image of the organ or object under inspection and for recording the image on an internal CCD device (video-endoscope) or for transmitting the image through the tube via a fiber optic bundle to an external video processor for viewing (fiber-endoscope). The endoscope can include one or more “operating” channels (typically 2-4 mm in diameter) that provide for passage of specialized medical instruments through the endoscope and into the field of view. Such specialized instruments (which can include biopsy forceps, brushes, needles, snares, scissors, graspers, cutters, clip appliers, etc.) can be used to take biopsies and retrieve organs (or pieces thereof) and/or foreign objects from the inside of the body. In some instruments (especially those with lateral-viewing optics), the distal tip of the operating channel incorporates a small deflectable elevator or bridge, which permits some directional control over the instrument exiting therefrom. These general principles apply to most endoscopes, but specific instruments differ in length, size, stiffness, as well as other characteristics as the instruments are typically designed for a particular application. Endoscopy can involve, for example, the gastrointestinal tract such as the esophagus, stomach and duodenum, small intestine, and colon. It can also involve the respiratory tract, the urinary tract, the female reproductive system, and the organs of the chest. It can also involve the interior of a joint (arthroscopy). Many endoscopic procedures are considered to be relatively painless and, at worst, associated with moderate discomfort. 
         [0005]    Laparoscopy is a minimally invasive surgical technique in which operations in the abdomen or thorax are performed through small incisions (usually 0.5-1.5 cm) via a laparoscope. There are generally two types of laparoscopes, including a telescopic rod lens system that is usually connected to a video camera (single chip or three chip) and a digital laparoscope where the camera is placed at the end of the laparoscope, thus eliminating the rod lens system. A fiber optic cable system connected to a light source (halogen or xenon is inserted through a surgical port to illuminate the operative field for viewing. The abdomen is usually insufflated with carbon dioxide gas to create a working and viewing space. Specialized surgical instruments can be introduced into the abdomen or thorax through a surgical port in order to take biopsies and retrieve organs (or pieces thereof) and/or foreign objects from the inside of the body. 
         [0006]    The specialized surgical instruments used for endoscopy, laparoscopy or arthroscopy generally include end effector means (e.g., graspers, cutters, forceps, scissors, clip appliers, etc.) mounted adjacent the distal end of a tube or coil. Handles (or other actuation control means) are mounted to the proximal end of the tube or coil and move an actuator axially through the tube or coil. The distal end of the actuator is mechanically coupled to the end effector means in a manner that transforms the axial movement of the actuator into the desired movement of the end effector means. Such specialized endoscopic, laparoscopic or arthroscopic surgical instruments are collectively referred to herein as endoscopic surgical instruments or endoscopic instruments. These general principles apply to most endoscopic instruments, but specific endoscopic instruments differ in length, size, stiffness, as well as other characteristics as the instruments are typically designed for a particular application as such instruments can be used for a wide variety of minimally invasive surgical procedures, including the endoscopic, laparoscopic and arthroscopic applications summarized above. 
         [0007]    Endoscopic surgical scissors instruments generally include a pair of scissor blades pivotably mounted adjacent the distal end of a tube or coil. The scissor blades have sharpened edges that effect cutting of tissue during pivotal movement of the scissor blades relative to one another. Handles (or other actuation control means) are mounted to the proximal end of the tube or coil and move an actuator axially through the tube or coil. The distal end of the actuator is mechanically coupled to the scissor blades in a manner that transforms the axial movement of the actuator into pivoting movement of the scissor blades. 
         [0008]    Endoscopic scissors instruments may be generally classified as either “single acting” or “double acting.” In a single acting instrument, a stationary scissor blade is supported adjacent the distal end of the tube or coil and a movable scissor blade is coupled to the distal end of the actuator and is supported adjacent the distal end of the tube or coil for rotation relative to the stationary scissor blade in accordance with actuation transmitted by the actuator. In double acting instruments, two scissor blades are coupled to the distal end of the actuator and supported adjacent the distal end of the tube or coil for rotation relative to one another in accordance with actuation transmitted by the actuator. 
         [0009]    The construction of the scissor blades theoretically supplies a moving contact point between the opposing cutting edges as the scissor blades are closed by their pivotable movement. In order to effect a smooth cutting action, the engaging cutting edges must be kept in a moving contact point throughout the closing of the scissor blades. Typical scissor designs usually accomplish this by the use of any of the following methods: firstly, via a mechanism or feature separated from the blades that biases the scissor blades together as the scissor blades are closed; secondly, by dimensioning the blades with a longitudinally bowed profile that forces the opposed scissor blades against each other as the scissor blades are closed and lastly by a very accurately constructed assembly with no mechanical slop in the dimensions of, or the positioning of, the scissors&#39; blades or related components 
         [0010]    The biasing means of the first example typically is accomplished by tightening the scissors&#39; pivot nut to remove all dimensional slop in the assembly or with a cammed surface behind the pivot area that effects biasing of the scissor blades closer together as they close over each other. In the second method, which is used most commonly for larger or longer scissor blades, such as those in a standard full-sized scissor as used in regular “open” surgery, a bowed-profile that runs along the longitudinal axis of the scissor blade forces the cutting edges together. This method gives a mostly adequate cutting performance for open style surgical scissors. However for smaller scissor blades such as those used in endoscopic devices, the total loss of resiliency, due to the stiffness of small blades, means that a bowed profile in the scissor blade will not work and will only result in the contacting cutting edges gouging each other or quickly wearing away. Therefore in the currently available endoscopic scissor devices such small non-resilient and rigid blades must be designed to maintain the edge to edge contact through the use of components with very stringent dimensional accuracies, tight tolerances and tight fits. This last design method involves difficult and costly assembly and manufacturing processes. In addition, the effects of using cams or similar features in the design of small endoscopic scissors is limited by the remoteness of the cam surface from the cutting edges and because of persistent assembly “slop” offers little improvement to the problem of maintaining edge to edge contact. These design schemes have historically failed to give small surgical scissor instruments the desired sensitive feel and cutting performance that surgeons require and are familiar with through their experience in open surgery using larger hand-held surgical scissors. 
       SUMMARY OF THE INVENTION 
       [0011]    The invention provides an endoscopic scissors instrument with small-size scissor blades with improved cutting performance through an improved biasing means whereby features contained in and as part of the blade itself automatically provide a preload to its cutting edge as two scissor blades move past one another. 
         [0012]    The invention also provides such an endoscopic scissors instrument that avoids inherently expensive components, assembly and manufacturing processes. 
         [0013]    According to the invention, an endoscopic scissors instrument includes an elongate hollow member having a proximal end and a distal end, an actuator that moves axially through the hollow member, and first and second scissor blades with respective cutting edges. At least one of the first and second scissor blades are rotatably coupled to the hollow member adjacent its distal end. At least one of the first and second scissor blades includes a base supporting a resilient leaf-spring portion that defines a respective cutting edge. The resilient leaf-spring portion extends from the base in a cantilevered arrangement along the length of the base. The cantilevered arrangement and angling of the leaf-spring portion serves to generate a spring force acting on the respective cutting edge such that, when in a loaded state, there is an automatic preloading force imparted between the cutting edges of the scissors&#39; blades that maintains a consistent and continuous mating force between the two opposed sharpened cutting edges, preferably over the complete range of rotational movement of the scissor. 
         [0014]    It will be appreciated that the endoscopic scissor instrument of the present invention provides improved edge to edge preload of the opposed scissor blades and thus enables superior cutting quality and operator feel for endoscopic scissor instruments where historically it has not been available. 
         [0015]    Additional advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a side view of an exemplary endoscopic scissors instrument that embodies the present invention. 
           [0017]      FIG. 2  is an isometric view of the distal portion of the endoscopic scissors instrument of  FIG. 1  in accordance with the present invention where the scissor blades of the instrument are positioned in an open configuration. 
           [0018]      FIG. 3  is an isometric view of the distal portion of the endoscopic scissors instrument of  FIG. 1  in accordance with the present invention where the scissor blades of the instrument are positioned in a closed configuration. 
           [0019]      FIGS. 4A and 4B  are schematic views of the scissor blades of the endoscopic scissors instrument of  FIGS. 1-3  in accordance with the present invention. 
           [0020]      FIG. 5A  is a side view of one of the scissor blades of  FIGS. 4A and 4B  in accordance with the present invention. 
           [0021]      FIG. 5B  is a cross-sectional view of the scissor blade of  FIG. 5A  along the section labeled  5 B- 5 B in  FIG. 5A . 
           [0022]      FIG. 5C  is a cross-sectional view of the scissor blade of  FIGS. 5A and 5B  along the section labeled  5 C- 5 C in  FIG. 5B . 
           [0023]      FIGS. 6A and 6B  are front cross-sectional views of the respective scissor blades of the instrument of  FIGS. 1-3  along section lines similar to  5 B- 5 B in  FIG. 5A  which illustrate the relief angles of the cutting features of the respective scissor blades relative to the corresponding blade supports in accordance with the present invention; the cross hatching of the section is omitted to more clearly show the relief angles depicted therein. 
           [0024]      FIG. 6C  is a cross-sectional view of the scissor blade of  FIG. 6B  along the section labeled  6 C- 6 C in  FIG. 6B  which illustrates the blade bias angle of the cutting feature of the respective scissor blade relative to its blade supports in accordance with the present invention; the cross hatching of the section is omitted to more clearly show the blade bias angle depicted therein. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]    For purposes herein, the “distal end” of a surgical instrument or any part thereof, is the end most distant from the surgeon and closest to the surgical site, while the “proximal end” of the instrument or any part thereof, is the end most proximate the surgeon and farthest from the surgical site. 
         [0026]    Turning now to  FIGS. 1 and 2 , an exemplary endoscopic scissors instrument  101  in accordance with the invention includes a housing  121  for supporting a handle assembly  123 . A hollow tubular member  125  is provided with a proximal end fixably coupled to the housing  121  and a distal end fixably coupled to a clevis  127 . The hollow tubular member  125  can be a coil to provide for bending and flexibility or can be a rigid or operator plastically deformable tube. A push rod actuator (not shown) extends through the hollow tubular member  125  to the clevis  127 . The push rod actuator is coupled to a pair of scissor blades  131 ,  133  via linkages, cams or other suitable coupling features and the scissor blades  131 ,  133  are rotatably mounted in the clevis  127  by a pivot post (not shown). In this configuration, axial movement of the push rod actuator within the hollow tubular member  125  causes the scissor blades  131 ,  133  to rotate around the post and thus pivot relative to one another. Additional details of the hollow tubular member  125 , the clevis  127 , and the push rod actuator may be obtained by reference to U.S. Pat. No. 5,192,298 to Smith et al., herein incorporated by reference in its entirety. It will also be appreciated that other actuating mechanisms and other mechanisms for causing rotation of the scissor blades could be utilized for the endoscopic scissors instrument of the invention. Indeed, rather than using a clevis with a post around which the scissor blades rotate, the scissor blades could be provided with arcuate grooves as disclosed in U.S. Pat. No. 4,712,545 to Honkanen, herein incorporated by reference in its entirety. The invention applies to single acting and double acting endoscopic surgical scissors. It will be appreciated by those skilled in the art that other mechanisms for linking the actuation mechanism to the scissor blades  131 ,  133  may be utilized, such as links and pins, or a pin riding in cammed slots, or other suitable actuating mechanism. Indeed, if desired, in a single acting instrument, the push rod or actuating wire could be directly connected to the scissor blade, and in double acting instruments, two connected push rods or actuating wires could be utilized for direct connection to the scissor blades. 
         [0027]    In the illustrative embodiment, the handle assembly  123  includes a movable front handle  135  and a fixed rear handle  137 . The front handle  135  has an aperture  139  defined therethrough which enables a user to grasp and move the front handle  137  relative to the rear handle  137 . More particularly, front handle  135  is selectively moveable by the user from a first position offset from the rear handle  137  to a second position in closer proximity to the rear handle  137 . Such movement is transmitted to axial movement of the push rod actuator  50  extending through the hollow tubular member  125  in order to impart pivotal movement of the scissor blades  131 ,  133  relative to one another. A control wheel  141  can be supported within the housing  121  and extend through sidewalls of the housing  121  to allow the user to rotate together the hollow tubular member  125 , the clevis  127  and the scissor blades  131 ,  133  mounted thereto or to rotate the clevis  127  and the scissor blades  131 ,  133  independently of and separately from, the hollow tubular member  125 . 
         [0028]    As shown in  FIGS. 2 and 3 , each of the scissor blades  131 ,  133  is provided with an inside cutting edge  151 ,  153  that contact one another as the scissor blades  131 ,  133  pivotably rotate relative to one another during use. During such rotation, a point of contact of the cutting edges  151 ,  153  moves along the cutting edges. In an open configuration, the point of contact is nearer to the pivot point or clevis ( FIG. 2 ). As the blades close, the point of contact moves further from the pivot point or clevis ( FIG. 3 ). In  FIG. 2 , the scissor blades  131 ,  133  are shown in an open configuration where the cutting edges  151 ,  153  are in bearing contact near the pivot point at a point shown generally by the circled portion  155 . 
         [0029]      FIGS. 4A and 4B  show a schematic view of scissor blades  131 ,  133 , each of are realized by two unitary parts  201 ,  203 . The first part  201 , referred to herein as a “blade support”, is thicker and stiffer than the second part  203 , referred to herein as a “cutting feature.” The thin cutting feature  203  includes a sharpened cutting edge ( 151 , 153 ) that extends along the entire length of the top edge of the cutting feature  203  preferably with a tapered profile as shown. Other profiled designs, such as a stepped profile or other variable profile can be used. 
         [0030]    As shown in  FIG. 5A , the blade support  201  includes a thru-hole  205  that receives a pivot post (not shown) as well as a cam-slot  207  disposed proximal to the thru hole  205  that receives a cam pin (not shown) connecting to the distal end of the actuator rod of the instrument. This arrangement provides for pivotal movement of the scissor blades  131 ,  133  relative to another in response to axial movement of the actuator rod as is well known. 
         [0031]    As best shown in the cross-section of  FIG. 5B , the thin cutting feature  203  of the scissor blades  131 ,  133  realizes a cantilever spring arrangement by fixing its bottom portion  209  to the blade support  201  with its top portion  211  angled or otherwise arranged to hold a bias along the length of the respective sharpened cutting edge (labeled  151  in  FIG. 5B ) that will ensure that the cutting edge intersects the opposing blade&#39;s cutting edge in a scissor assembly. In this cantilever spring arrangement, the thin cutting feature  203  acts as a resilient leaf-spring that allows for resilient deflection of the top portion  211  of the cutting feature  203  relative to its bottom portion  209  being rigidly held and positioned by the thick blade support  201 . This allows the sharpened cutting edge  204  to forcibly engage with the opposing blade&#39;s cutting edge in a resilient and deflective manner so no gouging or wear damages the cutting edges. Such resilient deflection is depicted by vector arrow  213  in  FIG. 5B . The cantilever spring arrangement of the cutting feature  203  extends along the length of the cutting feature  203  such that the resilient deflection of the top portion  211  relative to its bottom portion  209  and the blade support  201  is provided along the entire length of the cutting feature  203 . The cantilever spring arrangement of the cutting feature  203  also provides a spring moment that is primarily directed across the cutting edge of the cutting feature  203  laterally outward away from the blade support  201  in the direction of vector arrow  215  as shown in  FIG. 5B . 
         [0032]    The cantilever spring arrangement and positional bias of the cutting features  203  ensure that the cutting edges  151 ,  153  of the two blades  131 ,  133  are in intersecting planes as the blades  131 ,  133  are closed. In the preferred embodiment as illustrated in  FIGS. 6A-6C , the opposed cutting features  203  extend from respective base supports  201  at a relief angle a relative to the rotational planes  205  of the respective scissor blades. Moreover, as best shown in  FIG. 6C , the lengthwise profile of the respective cutting features  203  of the scissor blades are angled at a blade bias angle β relative to the rotational planes  205  of the scissor blades. The bias angle of the cutting features of the two blades point toward one another as is evident from  FIGS. 6A and 6B . In an illustrative embodiment, the relief angle α of the cutting features is in the range between 3° and 7° (more preferably on the order of 5°) and the blade bias angle β of the cutting features is in the range between 0.5° and 3° (more preferably on the order of 1.5°). Importantly, the relief angle α and the blade bias angle β of the cutting features  203  are provided such that selectively only the cutting edges  151 ,  153  of the two blades  131 ,  133  are on intersecting planes and therefore edge to edge contact one another is insured as the blades  131 ,  133  are closed. These design aspects of the leaf-spring provide a necessary blade-to-blade preload force as the blades  131 ,  133  are closed, which maintains a consistent and continuous forceful contact of the two opposed cutting edges  151 ,  153  over the complete range of rotational movement of the scissor blades  131 ,  133 . Using this design strategy enables a small scissor to use components and manufacturing techniques with much lower quality standards without need of the high tolerance and ultra fine positioning that is presently required in surgical scissors while elevating the cutting ability and feel to a level beyond that of existing endoscopic and other small surgical scissors. 
         [0033]    In the preferred embodiment, the blade support  201  of the respective blade has a thickness between 0.25 mm and 5 mm, while the cutting feature  203  of the respective blade has a thickness between 0.05 mm and 0.5 mm and a length less than 50 mm and preferably a the range between 5 mm and 20 mm.  FIG. 5C  illustrates an exemplary embodiment where the blade support  201  has a maximal thickness of 0.6 mm, and the cutting feature  203  has a thickness of 0.08 mm and a length of 7 mm. In the preferred embodiment, the scissor blades  131 ,  135  (including the cutting features  203  of the respective blades) are realized from high tensile strength stainless steel such as high chrome alloys. 
         [0034]    Advantageously, the endoscopic scissor instrument of the present invention provides an improved automatic edge to edge preload of the opposed scissor blades while avoiding the problems associated with a bowed blade profile and biasing cams used in the prior art, and thus enables superior cutting quality for endoscopic scissor instruments where historically it has not been available. 
         [0035]    There have been described and illustrated herein scissors instruments with improved scissor blades. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while the surgical scissors instrument illustrated herein for exemplary purposes were double acting scissors where both blades pivot relative to each other, it will be recognized that the invention can be applied to a single acting scissors with one blade fixed and the other blade pivoting relative to the fixed blade. It may also be applied to a scissors where only one blade incorporates the present invention coupled with a standard rigid opposing blade. Also, while particular actuation mechanisms were described for causing the pivoting of the scissor blades, it will be appreciated that other mechanism could be utilized. Thus, for example, the instrument could be a flexible instrument with an outer tube formed from a coiled element which could be used through an endoscope channel or a rigid instrument with a relatively stiff outer tube of structural plastic or tubular metal which could be used through a laparoscope or arthroscope. In addition, while particular materials and dimensions have been disclosed for the scissor blades of the endoscopic scissors instruments, it will be understood that other materials and dimensions can be used. Moreover, while a particular unitary configuration of the respective scissor blades is shown, other non-unitary configurations can be used. For example, it is contemplated that the cutting features of the respective blades can be a separate and distinct part that is secured to the blade support of the scissor blade by welding (e.g., by laser welding, spot welding, resistance welding), one or more screws or rivets, or other suitable mechanical fixation means. In this configuration, the blade support can be realized from a wide range of materials, such as a stainless steel, plastics, ceramics, etc. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as so claimed.

Technology Classification (CPC): 0