Patent Document

FIELD OF THE INVENTION  
         [0001]    The present invention relates, in general, to ultrasonic surgical instruments and, more particularly, to multifunctional curved blades with functional asymmetries for use with ultrasonic surgical instruments to minimize undesirable motion.  
         BACKGROUND OF THE INVENTION  
         [0002]    This application is related to the following copending patent applications: application Ser. No. 08/948,625 filed Oct. 10, 1997; application Ser. No. 08/949,133 filed Oct. 10, 1997; application Ser. No. 09/106,686 filed Jun. 29, 1998; application Ser. No. 09/337,077 filed Jun. 21, 1999; application Ser. No. ______ [Attorney Docket No. END-610]; application Ser. No. ______ [Attorney Docket No. END-616]; and application Ser. No. ______ [Attorney Docket No. END-618] which are hereby incorporated herein by reference.  
           [0003]    Ultrasonic instruments, including both hollow core and solid core instruments, are used for the safe and effective treatment of many medical conditions. Ultrasonic instruments, and particularly solid core ultrasonic instruments, are advantageous because they may be used to cut and/or coagulate organic tissue using energy in the form of mechanical vibrations transmitted to a surgical end-effector at ultrasonic frequencies. Ultrasonic vibrations, when transmitted to organic tissue at suitable energy levels and using a suitable end-effector, may be used to cut, dissect, or cauterize tissue. Ultrasonic instruments utilizing solid core technology are particularly advantageous because of the amount of ultrasonic energy that may be transmitted from the ultrasonic transducer through the waveguide to the surgical end-effector. Such instruments are particularly suited for use in minimally invasive procedures, such as endoscopic or laparoscopic procedures, wherein the end-effector is passed through a trocar to reach the surgical site.  
           [0004]    Ultrasonic vibration is induced in the surgical end-effector by, for example, electrically exciting a transducer which may be constructed of one or more piezoelectric or magnetostrictive elements in the instrument hand piece. Vibrations generated by the transducer section are transmitted to the surgical end-effector via an ultrasonic waveguide extending from the transducer section to the surgical end-effector. The waveguides and end-effectors are designed to resonate at the same frequency as the transducer. Therefore, when an end-effector is attached to a transducer the overall system frequency is still the same frequency as the transducer itself.  
           [0005]    The amplitude of the longitudinal ultrasonic vibration at the tip, d, behaves as a simple sinusoid at the resonant frequency as given by:  
             d=A  sin (ω t )  (equation 1)  
           [0006]    where:  
           [0007]    ω=the radian frequency which equals 2π times the cyclic frequency, f; and  
           [0008]    A=the zero-to-peak amplitude.  
           [0009]    The longitudinal excursion is defined as the peak-to-peak (p-t-p) amplitude, which is just twice the amplitude of the sine wave or 2A.  
           [0010]    Solid core ultrasonic surgical instruments may be divided into two types, single element end-effector devices and multiple-element end-effector. Single element end-effector devices include instruments such as scalpels, and ball coagulators, see, for example, U.S. Pat. No. 5,263,957. While such instruments as disclosed in U.S. Pat. No. 5,263,957 have been found eminently satisfactory, there are limitations with respect to their use, as well as the use of other ultrasonic surgical instruments. For example, single-element end-effector instruments have limited ability to apply blade-to-tissue pressure when the tissue is soft and loosely supported. Substantial pressure is necessary to effectively couple ultrasonic energy to the tissue. This inability to grasp the tissue results in a further inability to fully coapt tissue surfaces while applying ultrasonic energy, leading to less-than-desired hemostasis and tissue joining.  
           [0011]    The use of multiple-element end-effectors such as clamping coagulators include a mechanism to press tissue against an ultrasonic blade, that can overcome these deficiencies. A clamp mechanism disclosed as useful in an ultrasonic surgical device has been described in U.S. Pat. Nos. 3,636,943 and 3,862,630 to Balamuth. Generally, however, the Balamuth device, as disclosed in those patents, does not coagulate and cut sufficiently fast, and lacks versatility in that it cannot be used to cut/coagulate without the clamp because access to the blade is blocked by the clamp.  
           [0012]    Ultrasonic clamp coagulators such as, for example, those disclosed in U.S. Pat. Nos. 5,322,055 and 5,893,835 provide an improved ultrasonic surgical instrument for cutting/coagulating tissue, particularly loose and unsupported tissue, wherein the ultrasonic blade is employed in conjunction with a clamp for applying a compressive or biasing force to the tissue, whereby faster coagulation and cutting of the tissue, with less attenuation of blade motion, are achieved.  
           [0013]    Improvements in technology of curved ultrasonic instruments such as described in U.S. patent application Ser. No. 09/106,686 previously incorporated herein by reference, have created needs for improvements in other aspects of curved clamp coagulators. For example, U.S. Pat. No. 5,873,873 describes an ultrasonic clamp coagulating instrument having an end-effector including a clamp arm comprising a tissue pad. In the configuration shown in U.S. Pat. No. 5,873,873 the clamp arm and tissue pad are straight.  
           [0014]    The shape of an ultrasonic surgical blade or end-effector used in a clamp coagulator device defines at least four important aspects of the instrument. These are: (1) the visibility of the end-effector and its relative position in the surgical field, (2) the ability of the end-effector to access or approach targeted tissue, (3) the manner in which ultrasonic energy is coupled to tissue for cutting and coagulation, and (4) the manner in which tissue can be manipulated with the ultrasonically inactive end-effector. It would be advantageous to provide an improved ultrasonic clamp coagulator optimizing these four aspects of the instrument.  
           [0015]    However, as features are added to ultrasonic surgical instrument blades, the altered shape and asymmetries cause the blade to become unbalanced, meaning that the blade has the tendency to vibrate in directions other than the longitudinal direction along the length of the instrument. U.S. patent application Ser. No. 09/106,686 previously incorporated herein by reference, addressed balancing blades proximal to functional asymmetries using balance asymmetries. While U.S. patent application Ser. No. 09/106,686 has proven eminently successful at balancing blades and waveguides proximal to the balance asymmetry, there are some applications where some balancing may be desirable within the functional portion of an asymmetric blade.  
           [0016]    It would be desirable to provide a balanced ultrasonic surgical instrument blade within the functional area of the blade to optimize instrument performance. The blade described herein has been developed to address this desire.  
         SUMMARY OF THE INVENTION  
         [0017]    Disclosed is an ultrasonic surgical instrument that combines end-effector geometry to best affect the multiple functions of a shears-type configuration. The shape of the blade is characterized by a radiused cut offset by some distance to form a curved geometry. The cut creates a curved surface with multiple asymmetries causing multiple imbalances within the blade. Imbalance due to the curve of the instrument is corrected by a non-functional asymmetry proximal to the functional asymmetry. Imbalance due to the asymmetric cross-section of the blade is corrected by the appropriate selection of the volume and location of material removed from a functional asymmetry. The shape of the blade in one embodiment of the present invention is characterized by two radiused cuts offset by some distance to form a curved and potentially tapered geometry. These two cuts create curved surfaces including a concave surface and a convex surface. The length of the radiused cuts affects, in part, the acoustic balancing of the transverse motion induced by the curved shape. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    The novel features of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to organization and methods of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in conjunction with the accompanying drawings in which:  
         [0019]    [0019]FIG. 1 illustrates an ultrasonic surgical system including an elevational view of an ultrasonic generator, a sectioned plan view of an ultrasonic transducer, and a partially sectioned plan view of a clamp coagulator in accordance with the present invention;  
         [0020]    [0020]FIG. 2A is an exploded perspective view of a portion of a clamp coagulator in accordance with the present invention;  
         [0021]    [0021]FIG. 2B is an exploded perspective view of a portion of a clamp coagulator in accordance with the present invention;  
         [0022]    [0022]FIG. 3 is a partially sectioned plan view of a clamp coagulator in accordance with the present invention with the clamp arm assembly shown in an open position;  
         [0023]    [0023]FIG. 4 is a partially sectioned plan view of a clamp coagulator in accordance with the present invention with the clamp arm assembly shown in a closed position;  
         [0024]    [0024]FIG. 5 is a side view of a collar cap of the clamp coagulator;  
         [0025]    [0025]FIG. 6 is a front view of a collar cap of the clamp coagulator;  
         [0026]    [0026]FIG. 7 is a side view of a force limiting spring of the clamp coagulator;  
         [0027]    [0027]FIG. 8 is a front view of a force limiting spring of the clamp coagulator;  
         [0028]    [0028]FIG. 9 is a side view of a washer of the clamp coagulator;  
         [0029]    [0029]FIG. 10 is a front view of a washer of the clamp coagulator;  
         [0030]    [0030]FIG. 11 is a side view of a tubular collar of the clamp coagulator;  
         [0031]    [0031]FIG. 12 is a rear view of a tubular collar of the clamp coagulator;  
         [0032]    [0032]FIG. 13 is a front view of a tubular collar of the clamp coagulator;  
         [0033]    [0033]FIG. 14 is a side view of an inner knob of the clamp coagulator;  
         [0034]    [0034]FIG. 15 is a front view of an inner knob of the clamp coagulator;  
         [0035]    [0035]FIG. 16 is a bottom view of an inner knob of the clamp coagulator;  
         [0036]    [0036]FIG. 17 is a rear view of an outer knob of the clamp coagulator;  
         [0037]    [0037]FIG. 18 is a top view of an outer knob of the clamp coagulator;  
         [0038]    [0038]FIG. 19 is a top view of a yoke of the clamp coagulator;  
         [0039]    [0039]FIG. 20 is a side view of a yoke of the clamp coagulator;  
         [0040]    [0040]FIG. 21 is a front view of a yoke of the clamp coagulator;  
         [0041]    [0041]FIG. 22 is a perspective view of a yoke of the clamp coagulator;  
         [0042]    [0042]FIG. 23 is a perspective view of an end-effector of the clamp coagulator;  
         [0043]    [0043]FIG. 24 is a top perspective view of a clamp arm of the camp coagulator;  
         [0044]    [0044]FIG. 25 is a top view of an end-effector of the clamp coagulator;  
         [0045]    [0045]FIG. 26 is a side view of an end-effector of the clamp coagulator with the clamp arm open;  
         [0046]    [0046]FIG. 27 is a top view of a tissue pad of the clamp coagulator;  
         [0047]    [0047]FIG. 28 is a side view of a tissue pad of the clamp coagulator;  
         [0048]    [0048]FIG. 29 is a front view of a tissue pad of the clamp coagulator;  
         [0049]    [0049]FIG. 30 is a perspective view of a tissue pad of the clamp coagulator;  
         [0050]    [0050]FIG. 31 is a bottom perspective view of a clamp arm of the clamp coagulator;  
         [0051]    [0051]FIG. 32 is a first cross-sectional view of the clamp arm illustrated in FIG. 31;  
         [0052]    [0052]FIG. 33 is a second cross-sectional view of the clamp arm illustrated in FIG. 31;  
         [0053]    [0053]FIG. 34 is a bottom plan view of a blade of the clamp coagulator;  
         [0054]    [0054]FIG. 35 is a cross-sectional view of a blade of the clamp coagulator;  
         [0055]    [0055]FIG. 35A is a cross-sectional view of an alternate embodiment of a blade of the clamp coagulator; and  
         [0056]    [0056]FIG. 36 is a perspective view of an end-effector of the clamp coagulator. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0057]    The present invention will be described in combination with ultrasonic instruments as described herein. Such description is exemplary only, and is not intended to limit the scope and applications of the invention. For example, the invention is useful in combination with a multitude of ultrasonic instruments including those described in, for example, U.S. Pat. Nos. 5,938,633; 5,935,144; 5,944,737; 5,322,055, 5,630,420; and 5,449,370.  
         [0058]    [0058]FIG. 1 illustrates ultrasonic system  10  comprising an ultrasonic signal generator  15  with ultrasonic transducer  82 , hand piece housing  20 , and clamp coagulator  120  in accordance with the present invention. Clamp coagulator  120  may be used for open or laparoscopic surgery. The ultrasonic transducer  82 , which is known as a “Langevin stack”, generally includes a transduction portion  90 , a first resonator or end-bell  92 , and a second resonator or fore-bell  94 , and ancillary components. The ultrasonic transducer  82  is preferably an integral number of one-half system wavelengths (nλ/2) in length as will be described in more detail later. An acoustic assembly  80  includes the ultrasonic transducer  82 , mount  36 , velocity transformer  64  and surface  95 .  
         [0059]    The distal end of end-bell  92  is connected to the proximal end of transduction portion  90 , and the proximal end of fore-bell  94  is connected to the distal end of transduction portion  90 . Fore-bell  94  and end-bell  92  have a length determined by a number of variables, including the thickness of the transduction portion  90 , the density and modulus of elasticity of the material used to manufacture end-bell  92  and fore-bell  94 , and the resonant frequency of the ultrasonic transducer  82 . The fore-bell  94  may be tapered inwardly from its proximal end to its distal end to amplify the ultrasonic vibration amplitude as velocity transformer  64 , or alternately may have no amplification.  
         [0060]    The piezoelectric elements  100  may be fabricated from any suitable material, such as, for example, lead zirconate-titanate, lead meta-niobate, lead titanate, or other piezoelectric crystal material. Each of the positive electrodes  96 , negative electrodes  98 , and piezoelectric elements  100  has a bore extending through the center. The positive and negative electrodes  96  and  98  are electrically coupled to wires  102  and  104 , respectively. Wires  102  and  104  are encased within cable  25  and electrically connectable to ultrasonic signal generator  15  of ultrasonic system  10 .  
         [0061]    Ultrasonic transducer  82  of the acoustic assembly  80  converts the electrical signal from ultrasonic signal generator  15  into mechanical energy that results in primarily longitudinal vibratory motion of the ultrasonic transducer  82  and an end-effector  180  at ultrasonic frequencies. A suitable generator is available as model number GEN01, from Ethicon Endo-Surgery, Inc., Cincinnati, Ohio. When the acoustic assembly  80  is energized, a vibratory motion standing wave is generated through the acoustic assembly  80 . The amplitude of the vibratory motion at any point along the acoustic assembly  80  depends on the location along the acoustic assembly  80  at which the vibratory motion is measured. A minimum or zero crossing in the vibratory motion standing wave is generally referred to as a node (i.e., where motion is usually minimal), and an absolute value maximum or peak in the standing wave is generally referred to as an anti-node. The distance between an anti-node and its nearest node is one-quarter wavelength (λ/4).  
         [0062]    Wires  102  and  104  transmit the electrical signal from the ultrasonic signal generator  15  to positive electrodes  96  and negative electrodes  98 . The piezoelectric elements  100  are energized by an electrical signal supplied from the ultrasonic signal generator  15  in response to a foot switch  118  to produce an acoustic standing wave in the acoustic assembly  80 . The electrical signal causes disturbances in the piezoelectric elements  100  in the form of repeated small displacements resulting in large compression forces within the material. The repeated small displacements cause the piezoelectric elements  100  to expand and contract in a continuous manner along the axis of the voltage gradient, producing longitudinal waves of ultrasonic energy. The ultrasonic energy is transmitted through the acoustic assembly  80  to the end-effector  180 .  
         [0063]    In order for the acoustic assembly  80  to deliver energy to end-effector  180 , all components of acoustic assembly  80  must be acoustically coupled to the ultrasonically active portions of clamp coagulator  120 . The distal end of the ultrasonic transducer  82  may be acoustically coupled at surface  95  to the proximal end of an ultrasonic waveguide  179  by a threaded connection such as stud  50 .  
         [0064]    The components of the acoustic assembly  80  are preferably acoustically tuned such that the length of any assembly is an integral number of one-half wavelengths (nλ/ 22 ), where the wavelength λ is the wavelength of a pre-selected or operating longitudinal vibration drive frequency f d  of the acoustic assembly  80 , and where n is any positive integer. It is also contemplated that the acoustic assembly  80  may incorporate any suitable arrangement of acoustic elements.  
         [0065]    Referring now to FIGS. 2A and 2B, a clamp coagulator  120  of the surgical system  10  in accordance with the present invention is illustrated. The clamp coagulator  120  is preferably attached to and removed from the acoustic assembly  80  as a unit. The proximal end of the clamp coagulator  120  preferably acoustically couples to the distal surface  95  of the acoustic assembly  80  as shown in FIG. 1. It will be recognized that the clamp coagulator  120  may be coupled to the acoustic assembly  80  by any suitable means.  
         [0066]    The clamp coagulator  120  preferably includes an instrument housing  130 , and an elongated member  150 . The elongated member  150  can be selectively rotated with respect to the instrument housing  130  as further described below. The instrument housing  130  includes a pivoting handle portion  136 , and a fixed handle  132 A and  132 B, coupled to a left shroud  134  and a right shroud  138  respectively.  
         [0067]    The right shroud  138  is adapted to snap fit on the left shroud  134 . The right shroud  138  is preferably coupled to the left shroud  134  by a plurality of inwardly facing prongs  70  formed on the right shroud  138 . The plurality of prongs  70  are arranged for engagement in corresponding holes or apertures  140 , which are formed in the left shroud  134 . When the left shroud  134  is attached to the right shroud  138 , a cavity is formed therebetween to accommodate various components, such as an indexing mechanism  255  as further described below.  
         [0068]    The left shroud  134 , and the right shroud  138  of the clamp coagulator  120  are preferably fabricated from polycarbonate. It is contemplated that these components may be made from any suitable material without departing from the spirit and scope of the invention.  
         [0069]    Indexing mechanism  255  is disposed in the cavity of the instrument housing  130 . The indexing mechanism  255  is preferably coupled or attached on inner tube  170  to translate movement of the handle portion  136  to linear motion of the inner tube  170  to open and close the clamp arm assembly  300 . When the pivoting handle portion  136  is moved toward the fixed handle portion  130 , the indexing mechanism  255  slides the inner tube  170  rearwardly to pivot the clamp arm assembly  300  into a closed position. The movement of the pivoting handle portion  136  in the opposite direction slides the indexing mechanism  255  to displace the inner tube  170  in the opposite direction, i.e., forwardly, and hence pivot the clamp arm assembly  300  into its open position.  
         [0070]    The indexing mechanism  255  also provides a ratcheting mechanism to allow the elongated member  150  to rotate about its longitudinal axis relative to instrument housing  130 . The rotation of the elongated member  150  enables the clamp arm assembly  300  to be turned to a selected or desired angular position. The indexing mechanism  255  preferably includes a tubular collar  260  and yoke  280 .  
         [0071]    The tubular collar  260  of the indexing mechanism  255  is preferably snapped onto the proximal end of the inner tube  170  and keyed into opposing openings  168 . The tubular collar  260  is preferably fabricated from polyetherimide. It is contemplated that the tubular collar  260  may be constructed from any suitable material.  
         [0072]    Tubular collar  260  is shown in greater detail in FIGS. 11 through 13. The tubular collar  260  preferably includes an enlarged section  262 , and a bore  266  extending therethrough. The enlarged section  262  preferably includes a ring  272  formed around the periphery of the tubular collar  260  to form groove  268 . The groove  268  has a plurality of detents or teeth  269  for retaining the elongated member  150  in different rotational positions as the elongated member  150  is rotated about its longitudinal axis. Preferably, the groove  268  has twelve ratchet teeth to allow the elongated portion to be rotated in twelve equal angular increments of approximately 30 degrees. It is contemplated that the tubular collar  260  may have any number of teeth-like members. It will be recognized that the teeth-like members may be disposed on any suitable part of the tubular collar  260  without departing from the scope and spirit of the present invention.  
         [0073]    Referring back now to FIGS. 2A through 4, the pivoting handle portion  136  includes a thumb loop  142 , a first hole  124 , and a second hole  126 . A pivot pin  153  is disposed through first hole  124  of handle portion  136  to allow pivoting as shown by arrow  121  in FIG. 3. As thumb loop  142  of pivoting handle portion  136  is moved in the direction of arrow  121 , away from instrument housing  130 , a link  128  applies a forward force to yoke  280 , causing yoke  280  to move forward. Link  128  is connected to pivoting handle portion  136  by a pin  129 , and link  128  is connected to base  284  by a pin  127 .  
         [0074]    Referring back now to FIG. 2A, yoke  280  generally includes a holding or supporting member  282  and a base  284 . The supporting member  282  is preferably semi-circular and has a pair of opposing pawls  286  that extend inwardly to engage with the teeth  269  of the tubular collar  260 . It is contemplated that the pawls  286  may be disposed on any suitable part of the yoke  280  for engagement with the teeth  269  of the tubular collar  260  without departing from the spirit and scope of the invention. It will also be recognized that the yoke  280  may have any number of ratchet arms.  
         [0075]    Yoke  280  is shown in greater detail in FIGS. 19 through 22. The pivoting handle portion  136  preferably is partially disposed in a slot  147  of the base  284  of the yoke  280 . The base  284  also includes a base opening  287 , an actuator travel stop  290 , and a base pin-hole  288 . The pivot pin  153  is disposed through the base opening  287 . Yoke  280  pawls  286  transfer opening force to inner tube  170  through tubular collar  260 , resulting in the opening of clamp arm assembly  300 .  
         [0076]    The yoke  280  of the clamp coagulator  120  is preferably fabricated from polycarbonate. The yoke  280  may also be made from a variety of materials including other plastics, such as ABS, NYLON, or polyetherimide. It is contemplated that the yoke  280  may be constructed from any suitable material without departing from the spirit and scope of the invention.  
         [0077]    As illustrated in FIGS. 3 and 4, yoke  280  also transfers a closing force to clamp arm assembly  300  as pivoting handle portion  136  is moved toward instrument housing  130 . Actuator travel stop  290  contacts pivot pin  153  at the bottom of the stroke of pivoting handle portion  136 , stopping any further movement, or overtravel, of pivoting handle portion  136 . Pawls  286  of yoke  280  transfer force to tubular collar  260  through a washer  151 , a force limiting spring  155 , and collar cap  152 . Collar cap  152  is rigidly attached to tubular collar  260  after washer  151  and force limiting spring  155  have been assembled onto tubular collar  260  proximal to enlarged section  262 . Collar cap  152  is illustrated in greater detail in FIGS. 5 and 6. Force limiting spring  155  is illustrated in greater detail in FIGS. 7 and 8, and washer  151  is illustrated in greater detail in FIGS. 9 and 10. Thickness of washer  151  may be adjusted during design or manufacturing of clamp coagulator  120  to alter the pre-load of force limiting spring  155 . Collar cap  152  is attached to tubular collar  260  by ultrasonic welding, but may alternately be press fit, snap fit or attached with an adhesive.  
         [0078]    Referring to FIGS. 5 through 10, tubular collar  260 , washer  151 , force limiting spring  155 , and collar cap  152  provide a force limiting feature to clamp arm assembly  300 . As pivoting handle portion  136  is moved toward instrument housing  130 , clamp arm assembly  300  is rotated toward ultrasonic blade  88 . In order to provide both ultrasonic cutting, and hemostasis, it is desirable to limit the maximum force of clamp arm assembly  300  to 0.5 to 3.0 Lbs.  
         [0079]    [0079]FIGS. 5 and 6 illustrate collar cap  152  including a spring surface  158 . FIGS. 7 and 8 illustrate force limiting spring  155  including a cap surface  156 , a washer surface  157 , and a plurality of spring elements  159 . Force limiting spring  155  is described in the art as a wave spring, due to the shape of spring elements  159 . It is advantageous to use a wave spring for force limiting spring  155  because it provides a high spring rate in a small physical size well suited to an ultrasonic surgical instrument application where a central area is open for ultrasonic waveguide  179 . Force limiting spring  155  is biased between spring surface  158  of collar cap  152  and spring face  165  of washer  151 . Washer  151  includes a pawl face  167  (FIGS. 9 and 10) that contacts pawls  286  of yoke  280  after assembly of clamp coagulator  120  (see FIGS. 2 through 4).  
         [0080]    Referring now to FIGS. 2A, 2B, and FIGS. 14 through 18, a rotational knob  190  is mounted on the elongated member  150  to turn the elongated member  150  so that the tubular collar  260  rotates with respect to the yoke  280 . The rotational knob  190  may be fabricated from polycarbonate. The rotational knob  190  may also be made from a variety of materials including other plastics, such as a polyetherimide, nylon, or any other suitable material.  
         [0081]    The rotational knob  190  preferably has an enlarged section or outer knob  192 , an inner knob  194 , and an axial bore  196  extending therethrough. Inner knob  194  includes keys  191  that attach cooperatively to keyways  189  of outer knob  192 . The outer knob  192  includes alternating longitudinal ridges  197  and grooves  198  that facilitate the orientation of the rotational knob  190  and the elongated member  150  by a surgeon. The axial bore  196  of the rotational knob  190  is configured to snugly fit over the proximal end of the elongated member  150 .  
         [0082]    The inner knob  194  extends through an opening  139  in the distal end of the instrument housing  130 . Inner knob  194  includes a channel  193  to rotatably attach inner knob  194  into opening  139 . The inner knob  194  of the rotational knob  190  has a pair of opposing holes  199 . The opposing holes  199  are aligned as part of a passageway  195  that extends through the elongated member  150 , as will be described later.  
         [0083]    A coupling member, such as, for example, pin  163 , may be positioned through opposing holes  199  of the passageway  195 . The pin  163  may be held in the passageway  195  of the elongated member  150  by any suitable means, such as, for example, trapped between ribs in housing  130 , or a silicone or cyanoacrylate adhesive. The pin  163  allows rotational torque to be applied to the elongated member  150  from the rotational knob  190  in order to rotate the elongated member  150 .  
         [0084]    When the rotational knob  190  is rotated, the teeth  269  of the tubular collar  260  engage and ride up slightly on the corresponding pawls  286  of the yoke  280 . As the pawls  286  ride up on the teeth  269 , the supporting member  282  of the yoke  280  deflects outwardly to allow pawls  286  to slip or pass over the teeth  269  of the tubular collar  260 .  
         [0085]    In one embodiment, the teeth  269  of the tubular collar  260  are configured as ramps or wedges, and the pawls  286  of the yoke  280  are configured as posts. The teeth  269  of the tubular collar  260  and the pawls  286  of the yoke  280  may be reversed so that the teeth  269  of the tubular collar  260  are posts, and the pawls  286  of the yoke  280  are ramps or wedges. It is contemplated that the teeth  269  may be integrally formed or coupled directly to the periphery of the elongated member  150 . It will also be recognized that the teeth  269  and the pawls  286  may be cooperating projections, wedges, cam surfaces, ratchet-like teeth, serrations, wedges, flanges, or the like which cooperate to allow the elongated member  150  to be indexed at selective angular positions, without departing from the spirit and scope of the invention.  
         [0086]    As illustrated in FIG. 2B, the elongated member  150  of the clamp coagulator  120  extends from the instrument housing  130 . As shown in FIGS. 2B through 4, the elongated member  150  preferably includes an outer member or outer tube  160 , an inner member or inner tube  170 , and a transmission component or ultrasonic waveguide  179 .  
         [0087]    The outer tube  160  of the elongated member  150  preferably includes a hub  162 , a tubular member  164 , and a longitudinal opening or aperture  166  extending therethrough. The outer tube  160  preferably has a substantially circular cross-section and may be fabricated from stainless steel. It will be recognized that the outer tube  160  may be constructed from any suitable material and may have any suitable cross-sectional shape.  
         [0088]    The hub  162  of the outer tube  160  preferably has a larger diameter than the tubular member  164  does. The hub  162  has a pair of outer tube holes  161  to receive pin  163  to allow the hub  162  to be coupled to rotational knob  190 . As a result, the outer tube  160  will rotate when the rotational knob  190  is turned or rotated.  
         [0089]    The hub  162  of the outer tube  160  also includes wrench flats  169  on opposite sides of the hub  162 . The wrench flats  169  are preferably formed near the distal end of the hub  162 . The wrench flats  169  allow torque to be applied by a torque wrench to the hub  162  to tighten the ultrasonic waveguide  179  to the stud  50  of the acoustic assembly  80 . For example, U.S. Pat. Nos. 5,059,210 and 5,057,119, which are hereby incorporated herein by reference, disclose torque wrenches for attaching and detaching a transmission component to a mounting device of a hand piece assembly.  
         [0090]    Located at the distal end of the tubular member  164  of the outer tube  160  is an end-effector  180  for performing various tasks, such as, for example, grasping tissue, cutting tissue and the like. It is contemplated that the end-effector  180  may be formed in any suitable configuration.  
         [0091]    End-effector  180  and its components are shown in greater detail in FIGS. 23 through 33. The end-effector  180  generally includes a non-vibrating clamp arm assembly  300  to, for example, grip tissue or compress tissue against the ultrasonic blade  88 . The end-effector  180  is illustrated in FIGS. 23 and 26 in a clamp open position, and clamp arm assembly  300  is preferably pivotally attached to the distal end of the outer tube  160 .  
         [0092]    Looking first to FIGS. 23 through 26, the clamp arm assembly  300  preferably includes a clamp arm  202 , a jaw aperture  204 , a first post  206 A, a second post  206 B, and a tissue pad  208 . The clamp arm  202  is pivotally mounted about a pivot pin  207 A and pivot pin  207 B to rotate in the direction of arrow  122  in FIG. 3 when thumb loop  142  is moved in the direction indicated by arrow  121  in FIG. 3. By advancing the pivoting handle portion  136  toward the instrument housing  130 , the clamp arm  202  is pivoted about the pivot pin  207 A and pivot pin  207 B into a closed position. Retracting the pivoting handle portion  136  away from the instrument housing  130  pivots the clamp arm  202  into an open position.  
         [0093]    The clamp arm  202  has tissue pad  208  attached thereto for squeezing tissue between the ultrasonic blade  88  and clamp arm assembly  300 . The tissue pad  208  is preferably formed of a polymeric or other compliant material and engages the ultrasonic blade  88  when the clamp arm  202  is in its closed position. Preferably, the tissue pad  208  is formed of a material having a low coefficient of friction but which has substantial rigidity to provide tissue-grasping capability, such as, for example, TEFLON, a trademark name of E. I. Du Pont de Nemours and Company for the polymer polytetraflouroethylene (PTFE). The tissue pad  208  may be mounted to the clamp arm  202  by an adhesive, or preferably by a mechanical fastening arrangement as will be described below.  
         [0094]    As illustrated in FIGS. 23, 26 and  28 , serrations  210  are formed in the clamping surfaces of the tissue pad  208  and extend perpendicular to the axis of the ultrasonic blade  88  to allow tissue to be grasped, manipulated, coagulated and cut without slipping between the clamp arm  202  and the ultrasonic blade  88 .  
         [0095]    Tissue pad  208  is illustrated in greater detail in FIGS. 27 through 29. Tissue pad  208  includes a T-shaped protrusion  212 , a left protrusion surface  214 , a right protrusion surface  216 , a top surface  218 , and a bottom surface  219 . Bottom surface  219  includes the serrations  210  previously described. Tissue pad  208  also includes a beveled front end  209  to ease insertion during assembly as will be described below.  
         [0096]    Referring now to FIG. 26, the distal end of the tubular member  174  of the inner tube  170  preferably includes a finger or flange  171  that extends therefrom. The flange  171  has an opening  173 A and an opening  173 B (not shown) to receive the first post  206 A and second post  206 B of the clamp arm  202 . When the inner tube  170  of the elongated member  150  is moved axially, the flange  171  moves forwardly or rearwardly while engaging the first post  206 A and second post  206 B of the clamp arm assembly  300  to open and close the clamp arm  202 .  
         [0097]    Referring now to FIGS. 24, 25, and  31  through  33 , the clamp arm  202  of end-effector  180  is shown in greater detail. Clamp arm  202  includes an arm top  228  and an arm bottom  230 , as well as a straight portion  235  and a curved portion  236 . Straight portion  235  includes a straight T-slot  226 . Curved portion  236  includes a first top hole  231 , a second top hole  232 , a third top hole  233 , a fourth top hole  234 , a first bottom cut-out  241 , a second bottom cut-out  242 , a third bottom cut-out  243 , a forth bottom cut-out  244 , a first ledge  221 , a second ledge  222 , a third ledge  223 , a fourth ledge  224 , and a fifth ledge  225 .  
         [0098]    Top hole  231  extends from arm top  228  through clamp arm  202  to second ledge  222 . Top hole  232  extends from arm top  228  through clamp arm  202  to third ledge  223 . Top hole  233  extends from arm top  228  through clamp arm  202  to fourth ledge  224 . Top hole  234  extends from arm top  228  through clamp arm  202  to fifth ledge  225 . The arrangement of holes  231  through  234  and ledges  211  through  225  enables clamp arm  202  to include both the straight portion  235  and the curved portion  236 , while being moldable from a process such as, for example, metal injection molding (MIM). Clamp arm  202  may be made out of stainless steel or other suitable metal utilizing the MIM process.  
         [0099]    Referring to FIGS. 30 and 31, tissue pad  208  T-shaped protrusion  212  is insertable into clamp arm  202  straight T-slot  226 . Clamp arm  202  is designed such that tissue pad  208  may be manufactured as a straight component by, for example, injection molding, machining, or extrusion. As clamp arm  202  is inserted into straight T-slot  226  and moved progressively through curved portion  236 , beveled front edge  209  facilitates bending of tissue pad  208  to conform to the curvature of clamp arm  202 . The arrangement of holes  231  through  234  and ledges  211  through  225  enables clamp arm  202  to bend and hold tissue pad  208 .  
         [0100]    [0100]FIGS. 32 and 33 illustrate how clamp arm  202  holds tissue pad  208  in place while maintaining a bend in tissue pad  208  that conforms to curved portion  236  of clamp arm  202 . As illustrated in FIG. 32, third ledge  223  contacts right protrusion surface  216  providing a contact edge  238 , while left protrusion surface  214  is unsupported at this position. At a distal location, illustrated in FIG. 33, fourth ledge  224  contacts left protrusion surface  214  providing a contact edge  239 , while right protrusion surface  216  is unsupported at this location.  
         [0101]    Referring back now to FIG. 2 again, the inner tube  170  of the elongated member  150  fits snugly within the opening  166  of the outer tube  160 . The inner tube  170  preferably includes an inner hub  172 , a tubular member  174 , a circumferential groove  176 , a pair of opposing openings  178 , a pair of opposing openings  178 , and a longitudinal opening or aperture  175  extending therethrough. The inner tube  170  preferably has a substantially circular cross-section, and may be fabricated from stainless steel. It will be recognized that the inner tube  170  may be constructed from any suitable material and may be any suitable shape.  
         [0102]    The inner hub  172  of the inner tube  170  preferably has a larger diameter than the tubular member  174  does. The pair of opposing openings  178  of the inner hub  172  allow the inner hub  172  to receive the pin  163  to allow the inner tube  170  and the ultrasonic waveguide  179  to transfer torque for attaching ultrasonic waveguide  179  to stud  50  as previously described. An O-ring  220  is preferably disposed in the circumferential groove  176  of the inner hub  172 .  
         [0103]    The ultrasonic waveguide  179  of the elongated member  150  extends through aperture  175  of the inner tube  170 . The ultrasonic waveguide  179  is preferably substantially semi-flexible. It will be recognized that the ultrasonic waveguide  179  may be substantially rigid or may be a flexible wire. Ultrasonic vibrations are transmitted along the ultrasonic waveguide  179  in a longitudinal direction to vibrate the ultrasonic blade  88 .  
         [0104]    The ultrasonic waveguide  179  may, for example, have a length substantially equal to an integral number of one-half system wavelengths (nλ/2). The ultrasonic waveguide  179  may be preferably fabricated from a solid core shaft constructed out of material which propagates ultrasonic energy efficiently, such as titanium alloy (i.e., Ti-6Al-4V) or an aluminum alloy. It is contemplated that the ultrasonic waveguide  179  may be fabricated from any other suitable material. The ultrasonic waveguide  179  may also amplify the mechanical vibrations transmitted to the ultrasonic blade  88  as is well known in the art.  
         [0105]    As illustrated in FIG. 2, the ultrasonic waveguide  179  may include one or more stabilizing silicone rings or damping sheaths  110  (one being shown) positioned at various locations around the periphery of the ultrasonic waveguide  179 . The damping sheaths  110  dampen undesirable vibration and isolate the ultrasonic energy from the inner tube  170  assuring the flow of ultrasonic energy in a longitudinal direction to the distal end of the ultrasonic blade  88  with maximum efficiency. The damping sheaths  110  may be secured to the ultrasonic waveguide  179  by an interference fit such as, for example, a damping sheath described in U.S. patent application Ser. No. 08/808,652 hereby incorporated herein by reference.  
         [0106]    Referring again to FIG. 2, the ultrasonic waveguide  179  generally has a first section  182 , a second section  184 , and a third section  186 . The first section  182  of the ultrasonic waveguide  179  extends distally from the proximal end of the ultrasonic waveguide  179 . The first section  182  has a substantially continuous cross-section dimension.  
         [0107]    The first section  182  preferably has at least one radial waveguide hole  188  extending therethrough. The waveguide hole  188  extends substantially perpendicular to the axis of the ultrasonic waveguide  179 . The waveguide hole  188  is preferably positioned at a node but may be positioned at any other suitable point along the ultrasonic waveguide  179 . It will be recognized that the waveguide hole  188  may have any suitable depth and may be any suitable shape.  
         [0108]    The waveguide hole  188  of the first section  182  is aligned with the opposing openings  178  of the hub  172  and outer tube holes  161  of hub  162  to receive the pin  163 . The pin  163  allows rotational torque to be applied to the ultrasonic waveguide  179  from the rotational knob  190  in order to rotate the elongated member  150 . Passageway  195  of elongated member  150  includes opposing openings  178 , outer tube holes  161 , waveguide hole  188 , and opposing holes  199 .  
         [0109]    The second section  184  of the ultrasonic waveguide  179  extends distally from the first section  182 . The second section  184  has a substantially continuous cross-section dimension. The diameter of the second section  184  is smaller than the diameter of the first section  182 . As ultrasonic energy passes from the first section  182  of the ultrasonic waveguide  179  into the second section  184 , the narrowing of the second section  184  will result in an increased amplitude of the ultrasonic energy passing therethrough.  
         [0110]    The third section  186  extends distally from the distal end of the second section  184 . The third section  186  has a substantially continuous cross-section dimension. The third section  186  may also include small diameter changes along its length. The third section preferably includes a seal  187  formed around the outer periphery of the third section  186 . As ultrasonic energy passes from the second section  184  of the ultrasonic waveguide  179  into the third section  186 , the narrowing of the third section  186  will result in an increased amplitude of the ultrasonic energy passing therethrough.  
         [0111]    The third section  186  may have a plurality of grooves or notches (not shown) formed in its outer circumference. The grooves may be located at nodes of the ultrasonic waveguide  179  or any other suitable point along the ultrasonic waveguide  179  to act as alignment indicators for the installation of a damping sheath  110  during manufacturing.  
         [0112]    Still referring to FIG. 2, damping sheath  110  of the surgical instrument  150  surrounds at least a portion of the ultrasonic waveguide  179 . The damping sheath  110  may be positioned around the ultrasonic waveguide  179  to dampen or limit transverse side-to-side vibration of the ultrasonic waveguide  179  during operation. The damping sheath  110  preferably surrounds part of the second section  184  of the ultrasonic waveguide  179 . It is contemplated that the damping sheath  110  may be positioned around any suitable portion of the ultrasonic waveguide  179 . The damping sheath  110  preferably extends over at least one antinode of transverse vibration, and more preferably, a plurality of antinodes of transverse vibration. The damping sheath  110  preferably has a substantially circular cross-section. It will be recognized that the damping sheath  110  may have any suitable shape to fit over the ultrasonic waveguide  179  and may be any suitable length.  
         [0113]    The damping sheath  110  is preferably in light contact with the ultrasonic waveguide  179  to absorb unwanted ultrasonic energy from the ultrasonic waveguide  179 . The damping sheath  110  reduces the amplitude of non-axial vibrations of the ultrasonic waveguide  179 , such as, unwanted transverse vibrations associated with the longitudinal frequency of 55,500 Hz as well as other higher and lower frequencies.  
         [0114]    The damping sheath  110  is constructed of a polymeric material, preferably with a low coefficient of friction to minimize dissipation of energy from the axial motion or longitudinal vibration of the ultrasonic waveguide  179 . The polymeric material is preferably floura-ethylene propene (FEP) which resists degradation when sterilied using gamma radiation. It will be recognized that the damping sheath  110  may be fabricated from any suitable material, such as, for example, The damping sheath  110  preferably has an opening extending therethrough, and a longitudinal slit  111 . The slit  111  of the damping sheath  110  allows the damping sheath  110  to be assembled over the ultrasonic waveguide  179  from either end. It will be recognized that the damping sheath  110  may have any suitable configuration to allow the damping sheath  110  to fit over the ultrasonic waveguide  179 . For example, the damping sheath  110  may be formed as a coil or spiral or may have patterns of longitudinal and/or circumferential slits or slots. It is also contemplated that the damping sheath  110  may be fabricated without a slit  111  and the ultrasonic waveguide  179  may be fabricated from two or more parts to fit within the damping sheath  110 .  
         [0115]    It will be recognized that the ultrasonic waveguide  179  may have any suitable cross-sectional dimension. For example, the ultrasonic waveguide  179  may have a substantially uniform cross-section or the ultrasonic waveguide  179  may be tapered at various sections or may be tapered along its entire length.  
         [0116]    The ultrasonic waveguide  179  may also amplify the mechanical vibrations transmitted through the ultrasonic waveguide  179  to the ultrasonic blade  88  as is well known in the art. The ultrasonic waveguide  179  may further have features to control the gain of the longitudinal vibration along the ultrasonic waveguide  179  and features to tune the ultrasonic waveguide  179  to the resonant frequency of the system.  
         [0117]    The proximal end of the third section  186  of ultrasonic waveguide  179  may be coupled to the distal end of the second section  184  by an internal threaded connection, preferably near an antinode. It is contemplated that the third section  186  may be attached to the second section  184  by any suitable means, such as a welded joint or the like. Third section  186  includes ultrasonic blade  88 . Although the ultrasonic blade  88  may be detachable from the ultrasonic waveguide  179 , the ultrasonic blade  88  and ultrasonic waveguide  179  are preferably formed as a single unit.  
         [0118]    The ultrasonic blade  88  may have a length substantially equal to an integral multiple of one-half system wavelengths (nλ/2). The distal end of ultrasonic blade  88  may be disposed near an antinode in order to provide the maximum longitudinal excursion of the distal end. When the transducer assembly is energized, the distal end of the ultrasonic blade  88  is configured to move in the range of, for example, approximately 10 to 500 microns peak-to-peak, and preferably in the range of about 30 to 150 microns at a predetermined vibrational frequency.  
         [0119]    The ultrasonic blade  88  is preferably made from a solid core shaft constructed of material which propagates ultrasonic energy, such as a titanium alloy (i.e., Ti-6Al-4V) or an aluminum alloy. It will be recognized that the ultrasonic blade  88  may be fabricated from any other suitable material. It is also contemplated that the ultrasonic blade  88  may have a surface treatment to improve the delivery of energy and desired tissue effect. For example, the ultrasonic blade  88  may be micro-finished, coated, plated, etched, grit-blasted, roughened or scored to enhance coagulation and cutting of tissue and/or reduce adherence of tissue and blood to the end-effector. Additionally, the ultrasonic blade  88  may be sharpened or shaped to enhance its characteristics. For example, the ultrasonic blade  88  may be blade shaped, hook shaped, or ball shaped.  
         [0120]    As illustrated in FIGS. 34, 35 and  36 , the geometry of the ultrasonic blade  88  in accordance with the present invention delivers ultrasonic power more uniformly to clamped tissue than predicate devices. The end-effector  180  provides for improved visibility of the blade tip so that a surgeon can verify that the blade  88  extends across the structure being cut or coagulated. This is especially important in verifying margins for large blood vessels. The geometry also provides for improved tissue access by more closely replicating the curvature of biological structures. Blade  88  provides a multitude of edges and surfaces, designed to provide a multitude of tissue effects: clamped coagulation, clamped cutting, grasping, back-cutting, dissection, spot coagulation, tip penetration and tip scoring.  
         [0121]    The distal most tip of blade  88  has a surface  54  perpendicular to tangent  63 , a line tangent to the curvature at the distal tip. Two fillet-like features  61 A and  61 B are used to blend surfaces  51 ,  52  and  54 , thus giving a blunt tip that can be utilized for spot coagulation. The top of the blade  88  is radiused and blunt, providing a broad edge, or surface  56 , for clamping tissues between it and clamp arm assembly  300 . Surface  56  is used for clamped cutting and coagulation as well as manipulating tissues while the blade is inactive.  
         [0122]    The bottom surface has a spherical cut  53  that provides a narrow edge, or sharp edge  55 , along the bottom of blade  88 . The material cut is accomplished by, for example, sweeping a spherical end mill through an arc of radius R 1  and then finishing the cut using a second, tighter radius R 2  that blends the cut with a bottom surface  58  of the blade  88 . Radius R 1  is preferably within the range of 0.5 inches to 2 inches, more preferably within the range of 0.9 inches to 1.1 inches, and most preferably about 1.068 inches. Radius R 2  is preferably within the range of 0.125 inches to 0.5 inches, and most preferably about 0.25 inches. The second radius R 2  and the corresponding blend with the bottom surface  58  of blade  88  diminishes the stress concentrated at the end of the spherical cut relative to stopping the cut without this blend. The sharp edge  55  facilitates dissection and unclamped cutting (back-cutting) through less vascular tissues.  
         [0123]    Spherical cut  53  on bottom surface  58  of blade  88  creates sharp edge  55  while removing a minimal amount of material from blade  88 . Spherical cut  53  on the bottom of blade  88  creates a sharp edge  55  with an angle of α as described below. This angle a may be similar to predicate shears devices such as, for example, the LCS-K5 manufactured by Ethicon Endo-Surgery, Inc., Cincinnati, Ohio. However the blade  88  of the present invention cuts faster than predicate devices by virtue of the orientation of the angle α with respect to the typical application force. For the predicate shears devices, the edges are symmetric, spanning the application force equally. The edges for the present invention are asymmetric, with the asymmetry of the edges dictating how quickly tissue is separated or cut. The asymmetry is important in that it provides for an effectively sharper edge when ultrasonically activated, without removing a significant volume of material, while maintaining blunt geometry. This asymmetric angle as well as the curvature of the blade act to self tension tissue during back-cutting utilizing a slight hook-like or wedge-like action.  
         [0124]    Sharp edge  55  of ultrasonic blade  88  is defined by the intersection of surface  53  and a second surface  57  left after bottom surface  58  has received spherical cut  53 . Clamp arm assembly  300  is pivotally mounted on said distal end of outer tube  160  for pivotal movement with respect to ultrasonic blade  88 , for clamping tissue between clamp arm assembly  300  and ultrasonic blade  88 . Reciprocal movement of inner tube  170  pivots clamp arm assembly  300  through an arc of movement, defining a vertical plane  181 . A tangent  60  of spherical cut  53  at sharp edge  55  defines an angle α with a tangent  62  of second surface  57 , as illustrated in FIG. 35. The bisection  59  of angle a preferably does not lie in vertical plane  181 , but is offset by an angle β. Preferably the tangent  60  of spherical cut  53  lies within about 5 to 50 degrees of vertical plane  181 , and most preferably the tangent of spherical cut  53  lies about 38.8 degrees from vertical plane  181 . Preferably angle a is within the range of about 90 to 150 degrees, and most preferably angle a is about 121.6 degrees.  
         [0125]    Looking to FIG. 35A, an alternate embodiment of the present invention is illustrated with an asymmetric narrow edge. A tangent  60 A of a spherical cut  53 A at a sharp edge  55 A defines an angle αA with a tangent  62 A of a second surface  57 A, as illustrated in FIG. 35A. A bisection  59 A of angle αA preferably does not lie in a vertical plane  181 A, but is offset by an angle βA.  
         [0126]    The curved shape of the design of ultrasonic blade  88  also results in a more uniformly distributed energy delivery to tissue as it is clamped against the blade  88 . Uniform energy delivery is desired so that a consistent tissue effect (thermal and transection effect) along the length of end-effector  180  is achieved. The distal most 15 millimeters of blade  88  is the working portion, used to achieve a tissue effect. As will be further described below, the displacement vectors for locations along the curved shears blade  88  have directions that, by virtue of the improvements of the present invention over predicate instruments, lie largely in the x-y plane illustrated in FIGS. 34 and 35. The motion, therefore, of blade  88  lies within a plane (the x-y plane) that is perpendicular to the direction of the clamping force from clamp arm assembly  300 .  
         [0127]    Straight symmetric ultrasonic blades in general have tip excursions that lie along the longitudinal axis, designated the x-axis in FIGS. 34 and 35. Transverse motion is usually undesirable because it results in undesirable heat generation in inner tube  170 . When a functional asymmetry is added to an ultrasonic blade, such as a curved end-effector as described in U.S. patent application Ser. No. 09/106,686 previously incorporated herein by reference, the functional asymmetry creates an imbalance in the ultrasonic waveguide. If the imbalance is not corrected, then undesirable heat, noise, and compromised tissue effect occur. Although U.S. patent application Ser. No. 09/106,686 teaches how to provide ultrasonic blades that are balanced proximal to the balance asymmetry, the distal portion of the end-effector has an excursion in at least two axes. If the end-effector has a single plane of functional asymmetry, such as a curved end-effector, but the blade is otherwise symmetric, then the excursion will lie in a plane at the distal most end.  
         [0128]    It is often desirable to minimize any ultrasonic blade  88  excursion in the z-axis direction. Excursion of ultrasonic blade  88  in the z-axis direction causes system inefficiencies, resulting in undesirable heating, power loss, and possibly noise. Excursion of ultrasonic blade  88  in the z-axis direction at end-effector  180  causes the ultrasonic blade  88  to impact tissue lying between ultrasonic blade  88  and clamp arm assembly  300 . It is desirable to limit ultrasonic blade  88  excursion to the x-y plane shown in FIGS. 34 and 35. This allows ultrasonic blade  88  to rub tissue lying between ultrasonic blade  88  and clamp arm assembly  300  without impact, which optimizes heating of the tissue, and thus provides optimal coagulation. Minimizing z-axis excursion both proximal to the end-effector  180 , and in ultrasonic blade  88 , may be accomplished by proper selection of a spherical cut  53 .  
         [0129]    However, an ultrasonic end-effector  180  with an ultrasonic blade  88  that has multiple functional asymmetries, such as ultrasonic blade  88  as illustrated in FIGS. 34 through 36, will naturally have a tendency to include tip excursion in all three axes, x, y, and z if not balanced properly. For example, ultrasonic blade  88  as illustrated in FIG. 34 is curved in the y direction at its distal end. This curvature, although balanced proximal to end-effector  180 , will cause ultrasonic blade  88  to have excursions in both the x and y directions when activated. Adding spherical cut  53  subsequently adds another level of asymmetry to ultrasonic blade  88 , causing tip excursion in all three axes if not corrected, and also causing z-axis imbalances in ultrasonic waveguide  179  which decreases efficiency.  
         [0130]    It is possible to minimize z-axis tip excursion proximal to the functional asymmetry, and therefore maximize efficiency with improved tissue effect, by providing a functional asymmetry optimized to minimize z-axis excursion in ultrasonic waveguide  179 . As illustrated in FIG. 34, spherical cut  53  may extend proximally into ultrasonic blade  88 , from the most distal end, to any position. For example, FIG. 34 illustrates a first position  66 , a second position  67 , and a third position  68 , for spherical cut  53  to extend into ultrasonic blade  88 .  
         [0131]    Table 1 below describes three possible lengths of spherical cuts  53  for ultrasonic blade  88  illustrated in FIG. 34 as first position  66 , second position  67 , and third position  68 . The rows of Table 1 correspond to the length of cut into the ultrasonic blade  88 , and the columns of Table 1 correspond to the balance condition and excursions along each axis for each cut length. It can be appreciated from Table 1 that providing spherical cut  53  to a length corresponding to first position  68  minimizes the z axis excursion proximal to the functional asymmetry. It is preferable to balance ultrasonic blade  88  below 15% z axis excursion proximal to the functional asymmetry and it is most preferable to balance ultrasonic blade  88  below 5% z axis excursion proximal to the functional asymmetry. Preferably clamp coagulator  120  is designed to be balanced when activated in air (loaded only by air), and then balance is verified under other load conditions.  
         [0132]    In Table 1, a normalized excursion percentage (% z) in a clamping instrument at the end-effector  88  is calculated by taking the magnitude of the excursion in the direction normal to the clamp arm when the clamp arm is in its fully closed position, and dividing that magnitude by the magnitude of the maximum tip vibration excursion (also called the primary tip vibration excursion), and then multiplying the dividend by one hundred. Primary tip vibration excursion is the magnitude of the major axis of the ellipse or ellipsoid created by a point on the distal most end of ultrasonic blade  88  when the ultrasonic blade  88  is activated. The measurement of excursions is more fully explained in IEC international standard 61847, titled Measurement and Declaration of the Basic Output Characteristics of ultrasonic surgical systems, hereby incorporated herein by reference. A normalized excursion percentage (%x, %y, %z) in ultrasonic blade  88  or ultrasonic waveguide  179  is calculated by taking the magnitude of a secondary vibration excursion, and dividing that magnitude by the magnitude of the primary tip vibration excursion, and then multiplying the dividend by one hundred. Secondary tip vibration excursion is the magnitude of a minor axis, or other arbitrary axis, of the ellipse or ellipsoid created by a point on the distal most end of ultrasonic blade  88  when the ultrasonic blade  88  is activated.  
         [0133]    Table 1. Three possible lengths to provide a range of balances for a 0.946 inch long blade with a radius of R 1  manufactured from Ti6Al-4V with the blade including a functional asymmetry.  
                                                                                 % x at distal   % y at distal   % z at distal               end of blade   end of blade   end of blade   % z proximal           88   88   88   to blade 88                                    Cut Length =   71.83   69.47   4.15   0.40       12.8 mm,       Location at first       position 68       Cut Length = 14.8   72.49   68.87   1.60   12.43        mm, Location at       second position 67       Cut Length = 8.2   74.54   66.03   9.21   8.25       mm, Location at       third position 66       5                  
 
         [0134]    Referring now to FIGS.  1 - 4 , the procedure to attach and detach the clamp coagulator  120  from the acoustic assembly  80  will be described below. When the physician is ready to use the clamp coagulator  120 , the physician simply attaches the clamp coagulator  120  onto the acoustic assembly  80 . To attach the clamp coagulator  120  to acoustic assembly  80 , the distal end of stud  50  is threadedly connected to the proximal end of the transmission component or ultrasonic waveguide  179 . The clamp coagulator  120  is then manually rotated in a conventional screw-threading direction to interlock the threaded connection between the stud  50  and the ultrasonic waveguide  179 .  
         [0135]    Once the ultrasonic waveguide  179  is threaded onto the stud  50 , a tool, such as, for example, a torque wrench, may be placed over the elongated member  150  of the clamp coagulator  120  to tighten the ultrasonic waveguide  179  to the stud  50 . The tool may be configured to engage the wrench flats  169  of the hub  162  of the outer tube  160  in order to tighten the ultrasonic waveguide  179  onto the stud  50 . As a result, the rotation of the hub  162  will rotate the elongated member  150  until the ultrasonic waveguide  179  is tightened against the stud  50  at a desired and predetermined torque. It is contemplated that the torque wrench may alternately be manufactured as part of the clamp coagulator  120 , or as part of the hand piece housing  20 , such as the torque wrench described in U.S. Pat. No. 5,776,155 hereby incorporated herein by reference.  
         [0136]    Once the clamp coagulator  120  is attached to the acoustic assembly  80 , the surgeon can rotate the rotational knob  190  to adjust the elongated member  150  at a desired angular position. As the rotational knob  190  is rotated, the teeth  269  of the tubular collar  260  slip over the pawls  286  of the yoke  280  into the adjacent notch or valley. As a result, the surgeon can position the end-effector  180  at a desired orientation. Rotational knob  190  may incorporate an indicator to indicate the rotational relationship between instrument housing  130  and clamp arm  202 . As illustrated in FIGS. 17 and 18, one of the ridges  197  of rotational knob  190  may be used to indicate the rotational position of clamp arm  202  with respect to instrument housing  130  by utilizing, for example, an enlarged ridge  200 . It is also contemplated that alternate indications such as the use of coloring, symbols, textures, or the like may also be used on rotational knob  190  to indicate position similarly to the use of enlarged ridge  200 .  
         [0137]    To detach the clamp coagulator  120  from the stud  50  of the acoustic assembly  80 , the tool may be slipped over the elongated member  150  of the surgical tool  120  and rotated in the opposite direction, i.e., in a direction to unthread the ultrasonic waveguide  179  from the stud  50 . When the tool is rotated, the hub  162  of the outer tube  160  allows torque to be applied to the ultrasonic waveguide  179  through the pin  163  to allow a relatively high disengaging torque to be applied to rotate the ultrasonic waveguide  179  in the unthreading direction. As a result, the ultrasonic waveguide  179  loosens from the stud  50 . Once the ultrasonic waveguide  179  is removed from the stud  50 , the entire clamp coagulator  120  may be thrown away.  
         [0138]    While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.

Technology Category: 1