Patent Description:
Ultrasonic surgical instruments are finding increasingly widespread applications in surgical procedures by virtue of the unique performance characteristics of such instruments. Depending upon specific instrument configurations and operational parameters, ultrasonic surgical instruments can provide substantially simultaneous cutting of tissue and homeostasis by coagulation, desirably minimizing patient trauma. The cutting action is typically effected by an end-effector at the distal end of the instrument, which transmits ultrasonic energy to tissue brought into contact with the end-effector. Ultrasonic instruments of this nature can be configured for open surgical use, laparoscopic or endoscopic surgical procedures including robotic-assisted procedures.

Ultrasonic surgical instruments have been developed that include a clamp mechanism to press tissue against the blade of the end-effector in order to couple ultrasonic energy to the tissue of a patient. Such an arrangement (sometimes referred to as a clamp coagulator shears or an ultrasonic transector) is disclosed in <CIT>; <CIT> and <CIT>.

The surgeon activates the clamp arm to press the clamp pad against the blade by squeezing on the handgrip or handle.

Some current designs of clamp coagulator shears utilize a foot pedal to energize the surgical instrument. The surgeon operates the foot pedal while simultaneously applying pressure to the handle to press tissue between the jaw and blade to activate a generator that provides energy that is transmitted to the cutting blade for cutting and coagulating tissue. Key drawbacks with this type of instrument activation include the loss of focus on the surgical field while the surgeon searches for the foot pedal, the foot pedal getting in the way of the surgeon's movement during a procedure and surgeon leg fatigue during long cases.

Various methods have been disclosed for curved end effector balancing, which include repositioning the mass along the end effector. The drawbacks of such methods are i) high stresses in the curved region, which makes the end effector more prone to fracture if it comes in contact with metal during surgery; ii) a shorter active length, which limits the vessel size that can be operated on, (the active length is defined as the length from the distal end of the blade to where the displacement is one half of the displacement at its distal end); and/or iii) the inability to separately balance orthogonal displacements.

Some current designs of clamp coagulator shears utilize handles that are either of a pistol or scissors, grips design. The scissor grip designs may have one thumb or finger grip that is immovable and fixed to the housing and one movable thumb or finger grip. This type of grip may not be entirely familiar to surgeons who use other open-type surgical instruments, such as hemostats, where both thumb and finger grips move in opposition to one another. Current designs have scissor arms that rotate around a fixed pivot or rotation point that is perpendicular to the longitudinal axis of the working element. This approach is limited since the relative motion between the two arms is completely rotational. This feature limits the ability to control the pressure profile between the two working ends when fully closed.

Some current designs of clamp coagulator shears are not specifically designed for delicate procedures where precise dissection, cutting and coagulation are required. An exemplary procedure is a thyroidectomy where precise dissection, cutting and coagulation is required to avoid critical blood vessels and nerve bundles.

It would be desirable to provide an ultrasonic surgical instrument that overcomes some of the deficiencies of current instruments. The ultrasonic surgical instrument described herein overcomes those deficiencies.

<CIT> (A1) describes an ultrasonic surgical clamp coagulator apparatus configured to effect cutting, coagulation, and clamping of tissue by cooperation of a clamping mechanism of the apparatus with an associated ultrasonic end-effector. The handle of the apparatus is configured to permit hand activation for cutting, coagulation, and clamping of tissue during surgical procedures. In order to promote convenient and efficient use of the apparatus, the fingertip controls are provided directly into the disposal shears handle in a position that allows surgeons to activate the device without repositioning their hand. The two buttons provide independent control of the two power levels available from the generator, matching the two foot pedal configuration of the prior art.

An ultrasonic clamp coagulator assembly embodying the principles of the present disclosure is configured to permit selective dissection, cutting, coagulation and clamping of tissue during surgical procedures.

A first expression of a first embodiment of the disclosure is for an ultrasonic waveguide including an ultrasonically actuated blade attached to the distal end of the waveguide; a tissue pad having a tissue engaging surface having a first width and a second width less than the first width; and a clamp member defining a distal portion and a proximal portion and moveable with respect to the blade and having an open position in which at least a portion of the clamp member is spaced from the blade and a closed position in which the clamp member is adjacent to the blade for clamping tissue between the tissue pad and the blade.

A second expression of a first embodiment includes a clamp member defining a first dimension and a second dimension in a first plane and the first dimension is greater than the second dimension and further defining a first dimension and a second dimension in a second plane and the first dimension is greater than the second dimension.

A first expression of a third embodiment includes a method of assembling a sterilized ultrasonic clamp coagulator apparatus including the steps of providing an ultrasonic waveguide having a proximal end and a distal end and an ultrasonically actuated blade attached to the distal end of the waveguide; a tissue pad having a flange and a tissue engaging surface having a first width and a second width less than the first width; a clamp member moveable with respect to said end-effector and having an open position in which at least a portion of the clamp member is spaced from the blade and a closed position in which the clamp member is adjacent to the blade for clamping tissue between the tissue pad and the blade, and where the clamp member includes a slot for slidably receiving the flange and slidably engaging the flange within the slot and then sterilizing the clamp coagulator apparatus.

A first expression of a fourth embodiment of an ultrasonic surgical instrument is for a housing configured to accept a transducer and further defining a longitudinal axis; a first switch positioned on the housing for actuation by one or more fingers of a user in a direction parallel to the longitudinal axis and further electrically connected to a generator for providing an electrical signal to the generator for controlling a first level of ultrasonic energy delivered by the transducer.

A second expression of a fourth embodiment of an ultrasonic surgical instrument is for a second switch positioned on the housing for actuation by one or more fingers of a user in a direction parallel to the longitudinal axis and further electrically connected to a generator for providing an electrical signal to the generator for controlling a second level of ultrasonic energy delivered by the transducer.

A first expression of a fifth embodiment of an ultrasonic surgical instrument is for an ultrasonic waveguide defining a longitudinal axis, having a proximal end, a most distal node and a distal end and an ultrasonically actuated blade positioned at the distal end of the waveguide and which defines a functional asymmetry within a first plane, a first balance asymmetry distal to the most distal node and proximal to the blade; and a second balance asymmetry proximal to the most distal node.

A first expression of a sixth embodiment of an ultrasonic surgical instrument is for a housing, an outer shroud having a proximal end joined to the housing, an ultrasonic waveguide positioned within the outer tube, an ultrasonically actuated blade positioned at the distal end of the waveguide, and an actuating lever for operating a clamp arm located at the distal end of the lever. The actuating lever has camming members, which operatively engage the outer tube such that movement of the actuating lever positions the clamp arm between open and clamped positions relative to the blade.

A second expression of a sixth embodiment of an ultrasonic instrument is for stationary finger ring that defines an opening having a length L and the housing and a transducer are sized to position a center of gravity of the surgical instrument at the housing within the dimension of length L.

A first expression of a first embodiment of a torque wrench for use with an ultrasonic clamp coagulator apparatus is for a hand wrench body, a cantilever arm movably attached to said wrench body, at least one tooth located at the cantilever arm's distal end, and an adaptor rotatably attached to the hand wrench and comprising a cam for operatively engaging the tooth.

The invention itself, however, may best be understood by reference to the following description, taken in conjunction with the accompanying drawings in which:.

The present disclosure is particularly directed to an improved ultrasonic surgical clamp coagulator apparatus which is configured for effecting tissue cutting, coagulation, and/or clamping during surgical procedures, including delicate surgical procedures, such as a thyroidectomy. The present apparatus is configured for use in open surgical procedures. Versatile use is facilitated by selective use of ultrasonic energy. When ultrasonic components of the apparatus are inactive, tissue can be readily gripped and manipulated, as desired, without tissue cutting or damage. When the ultrasonic components are activated, the apparatus permits tissue to be gripped for coupling with the ultrasonic energy to effect tissue coagulation, with application of increased pressure efficiently effecting tissue cutting and coagulation. If desired, ultrasonic energy can be applied to tissue without use of the clamping mechanism of the apparatus by appropriate manipulation of the ultrasonic blade.

As will become apparent from the following description, the present clamp coagulator apparatus is particularly configured for disposable use by virtue of its straightforward construction. As such, it is contemplated that the apparatus be used in association with an ultrasonic generator unit of a surgical system, whereby ultrasonic energy from the generator unit provides the desired ultrasonic actuation for the present clamp coagulator apparatus. It will be appreciated that a clamp coagulator apparatus embodying the principles of the present disclosure can be configured for non-disposable or multiple use, and non-detachably integrated with an associated ultrasonic generator unit. However, detachable connection of the present clamp coagulator apparatus with an associated ultrasonic generator unit is presently preferred for single-patient use of the apparatus.

With specific reference now to <FIG> and <FIG>, an embodiment of a surgical system <NUM>, including an ultrasonic surgical instrument <NUM> in accordance with the present disclosure is illustrated. The surgical system <NUM> includes an ultrasonic generator <NUM> connected to an ultrasonic transducer <NUM> via cable <NUM>, and an ultrasonic surgical instrument <NUM>. It will be noted that, in some applications, the ultrasonic transducer <NUM> is referred to as a "hand piece assembly" because the surgical instrument of the surgical system <NUM> is configured such that a surgeon may grasp and manipulate the ultrasonic transducer <NUM> during various procedures and operations. A suitable generator is the GEN04 (also referred to as Generator <NUM>) sold by Ethicon Endo-Surgery, Inc. of Cincinnati, Ohio. A suitable transducer is disclosed in co-pending U. patent application filed on October <NUM>, <NUM>, serial no. [ ] (Attorney Docket # END5747USNP1), entitled MEDICAL ULTRASOUND SYSTEM AND HANDPIECE AND METHODS FOR MAKING AND TUNING.

Ultrasonic transducer <NUM>, and an ultrasonic waveguide <NUM> together provide an acoustic assembly of the present surgical system <NUM>, with the acoustic assembly providing ultrasonic energy for surgical procedures when powered by generator <NUM>. The acoustic assembly of surgical instrument <NUM> generally includes a first acoustic portion and a second acoustic portion. In the present embodiment, the first acoustic portion comprises the ultrasonically active portions of ultrasonic transducer <NUM>, and the second acoustic portion comprises the ultrasonically active portions of transmission assembly <NUM>. Further, in the present embodiment, the distal end of the first acoustic portion is operatively coupled to the proximal end of the second acoustic portion by, for example, a threaded connection.

The ultrasonic surgical instrument <NUM> includes amulti-piece handle assembly <NUM> adapted to isolate the operator from the vibrations of the acoustic assembly contained within transducer <NUM>. The handle assembly <NUM> can be shaped to be held by a user in a conventional manner, but it is contemplated that the present ultrasonic surgical instrument <NUM> principally be grasped and manipulated in a scissor-like arrangement provided by a handle assembly of the instrument, as will be described. While multi-piece handle assembly <NUM> is illustrated, the handle assembly <NUM> may comprise a single or unitary component. The proximal end of the ultrasonic surgical instrument <NUM> receives and is fitted to the distal end of the ultrasonic transducer <NUM> by insertion of the transducer into the handle assembly <NUM>. The ultrasonic surgical instrument <NUM> may be attached to and removed from the ultrasonic transducer <NUM> as a unit. The ultrasonic surgical instrument <NUM> may include a handle assembly <NUM>, comprising mating housing portions <NUM> and <NUM> and an ultrasonic transmission assembly <NUM>. The elongated transmission assembly <NUM> of the ultrasonic surgical instrument <NUM> extends orthogonally from the instrument handle assembly <NUM>.

The handle assembly <NUM> may be constructed from a durable plastic, such as polycarbonate or a liquid crystal polymer. It is also contemplated that the handle assembly <NUM> may alternatively be made from a variety of materials including other plastics, ceramics or metals. Traditional unfilled thermoplastics, however, have a thermal conductivity of only about <NUM> W/m°K (Watt/ meter-°Kelvin). In order to improve heat dissipation from the instrument, the handle assembly may be constructed from heat conducting thermoplastics, such as high heat resistant resins liquid crystal polymer (LCP), Polyphenylene Sulfide (PPS), Polyetheretherketone (PEEK) and Polysulfone having thermal conductivity in the range of <NUM>-<NUM> W/m°K. PEEK resin is a thermoplastics filled with aluminum nitride or boron nitride, which are not electrically conductive. The thermally conductive resin helps to manage the heat within smaller instruments.

The transmission assembly <NUM> includes a waveguide <NUM> and a blade <NUM>. It will be noted that, in some applications, the transmission assembly is sometimes referred to as a "blade assembly". The waveguide <NUM>, which is adapted to transmit ultrasonic energy from transducer <NUM> to the tip of blade <NUM> may be flexible, semi-flexible or rigid. The waveguide <NUM> may also be configured to amplify the mechanical vibrations transmitted through the waveguide <NUM> to the blade <NUM> as is well known in the art. The waveguide <NUM> may further have features to control the gain of the longitudinal vibration along the waveguide <NUM> and features to tune the waveguide <NUM> to the resonant frequency of the system. In particular, waveguide <NUM> may have any suitable cross-sectional dimension. For example, the waveguide <NUM> may have a substantially uniform cross-section or the waveguide <NUM> may be tapered at various sections or may be tapered along its entire length.

Ultrasonic waveguide <NUM> may, for example, have a length substantially equal to an integral number of one-half system wavelengths (nλ/<NUM>). The ultrasonic waveguide <NUM> and blade <NUM> 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-6AI-4V), aluminum alloys, sapphire, stainless steel or any other acoustically compatible material.

Ultrasonic waveguide <NUM> may further include at least one radial hole or aperture <NUM> extending therethrough, substantially perpendicular to the longitudinal axis of the waveguide <NUM>. The aperture <NUM>, which may be positioned at a node, is configured to receive a connector pin <NUM>, discussed below, which connects the waveguide <NUM>, to the handle assembly <NUM>.

Blade <NUM> may be integral with the waveguide <NUM> and formed as a single unit. In an alternate expression of the current embodiment, blade <NUM> may be connected by a threaded connection, a welded joint, or other coupling mechanisms. The distal end of the blade <NUM> is disposed near an anti-node <NUM> in order to tune the acoustic assembly to a preferred resonant frequency fo when the acoustic assembly is not loaded by tissue. When ultrasonic transducer <NUM> is energized, the distal end of blade <NUM> or blade tip 79a is configured to move substantially longitudinally (along the x axis) in the range of, for example, approximately <NUM> to <NUM> microns peak-to-peak, and preferably in the range of about <NUM> to about <NUM> microns at a predetermined vibrational frequency fo of, for example, <NUM>,<NUM>. Blade tip 79a also preferably vibrates in the y axis at about <NUM> to about <NUM> percent of the motion in the x axis.

The blade tip 79a provides a functional asymmetry or curved portion for improved visibility at the blade tip so that a surgeon can verify that the blade <NUM> 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 <NUM> 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.

Blade tip 79a is commonly referred to as a functional asymmetry. That is, the blade (functionally, the blade provides a multitude of tissue effects) lies outside the longitudinal axis of waveguide <NUM> (that is, asymmetrical with the longitudinal axis), and accordingly creates an imbalance in the ultrasonic waveguide. If the imbalance is not corrected, then undesirable heat, noise, and compromised tissue effect occur.

It is possible to minimize unwanted tip excursion in the y and z axes, and therefore maximize efficiency with improved tissue effect, by providing one or more balance asymmetries or balancing features proximal to the blade functional asymmetry.

Referring now to <FIG>, transmission assembly <NUM> includes one or more balancing features placed at blade <NUM>, at a position proximal and/or distal to the distal most node <NUM>. In addition, the balancing features at the waveguide <NUM> are shaped to balance the two orthogonal modes in the y and z axes, separately. The size and shape and location of the balance features allow flexibility to reduce stress at the blade <NUM>, make the active length longer and separately balance the two orthogonal modes.

<FIG> show a single balance cut <NUM> at the waveguide <NUM> distal to node <NUM>. In this embodiment balance cut <NUM> has side walls perpendicular to the longitudinal axis of waveguide <NUM> and the bottom cut is parallel to the longitudinal axis of waveguide <NUM>. In this embodiment the high stresses experienced during operation are localized at the balancing cut <NUM>, which is away from the more sensitive curved region at the blade <NUM>.

<FIG> shows two balancing features <NUM> and 82a, one distal and one proximal to the node <NUM>. Adding second balance cut 82a, proximal to node <NUM> further eliminates the orthogonal bending modes thereby providing a more pure longitudinal motion (x direction) and removing the overlapping bending modes (y and z direction). Accordingly, the blade <NUM> is better balanced and has a longer active length.

<FIG> shows two balancing features 82c and 82a, distal and proximal to the node <NUM>. An angled bottom cut at balance feature 82c allows individual balancing of the bending mode in the z direction.

<FIG> show two balancing features <NUM> and 82d, distal and proximal to the node <NUM>. The side walls of balance feature 82d are angled with respect to each other in the x-z plane and provide for individual balancing of the bending mode in the y direction. The angled side walls define an included angle ? of between <NUM>° and about <NUM>°, preferably between about <NUM>° and about <NUM>°, and more preferably between about <NUM>° and about <NUM>°. The weight removed at each balance feature is a function of multiple parameters including the radius of curvature at blade tip 79a and the desired level of removal of the overlapping bending modes in the y and z direction. In an illustrative example, the balance cut <NUM> represents a weight reduction of about <NUM> (<NUM>) to about <NUM> (<NUM> oz. ), and most preferably about <NUM> (<NUM> oz). The balance cut 82d represents a weight reduction of about <NUM> (<NUM>) to about <NUM> (<NUM> oz. ), and most preferably about <NUM> (<NUM> oz).

<FIG> shows one balance cut 82e in the curved blade region in addition to balance feature <NUM>, distal to node <NUM>. Balance cut 82e allows for balancing as well as improved acoustic performance as a result of wide frequency separation of transverse modes from the fundamental frequency, which is the longitudinal mode frequency.

As would be apparent to one skilled in the art, any combination of balance cuts <NUM> through 82e are possible to provide balancing of a waveguide and curved blade.

<FIG> shows that the profile produced by the balancing cut features of <FIG> produces a <NUM> longer active length along the longitudinal displacement direction than is available from an LCS-C5 ultrasonic clamp coagulator, sold by Ethicon Endo-Surgery, Inc. (where the y axis is representative of the ratio between the displacement anywhere along blade tip 79a and the displacement at the most distal end of blade tip 79a). A longer active length is desirable for cutting and coagulating large vessels, for example, <NUM>-<NUM> vessels.

<FIG> shows that the profile produced by the balancing features of <FIG> produces a <NUM> longer active length (along the vector sum of displacements in the x, y and z directions) than is available from an LCS-C5 ultrasonic clamp coagulator, which is desirable for cutting and coagulating large vessels, for example, <NUM>-<NUM> vessels.

Referring back to <FIG> and <FIG> an outer tubular member or outer shroud <NUM> attaches to the most proximal end of handle assembly <NUM>. Attached to the distal end of the outer shroud <NUM> is a distal shroud <NUM>. Both the outer shroud <NUM> and distal shroud <NUM> may attach via a snap fit, press fit, glue or other mechanical means. Extending distally from the distal shroud <NUM> is the end-effector <NUM>, which comprises the blade <NUM> and clamp member <NUM>, also commonly referred to as a jaw, in combination with one or more tissue pads <NUM>. A seal <NUM> may be provided at the distal-most node <NUM>, nearest the end-effector <NUM>, to abate passage of tissue, blood, and other material in the region between the waveguide <NUM> and the distal shroud <NUM>. Seal <NUM> may be of any known construction, such as an o-ring or silicon overmolded at node <NUM>.

Referring now to <FIG> and <FIG>, blade <NUM> is curved along with the associated clamp member <NUM>. This is illustrative only, and blade <NUM> and a corresponding clamp member <NUM> may be of any shape as is known to the skilled artisan. One benefit of the disclosure, however, is the ability to perform finer, more delicate surgical procedures. It is also multifunctional and able to dissect tissue as well as coagulate and transect.

The ability to finely dissect is enabled primarily by the tapering of the end effector <NUM>. The end effector is tapered in two planes, which mimics typical hemostats. This allows the user to create windows in the tissue and then spread the tissue apart more easily. The blade <NUM> and clamp member <NUM> are tapered in both the x and z directions from the proximal end to the distal end. The pad <NUM> is only tapered in the Z direction. That is, the clamp pad <NUM> has a constant thickness, but the width of the clamp pad <NUM> at the distal end is less than the width at the proximal end. Accordingly, the surface area of section A is greater than the surface area of section B.

In addition to the taper, the radius at the distal end of the blade <NUM> and clamp member <NUM> also promotes fine dissection. The radius at the tip of the clamp member <NUM> is approximately <NUM> (<NUM> inches), and the blade radius is approximately <NUM> (<NUM> inches).

With specific reference to <FIG>, blade <NUM> is defined by an inside radius R1 and an outside radius R2 measured at a distance D1 from the longitudinal axis. The dimensions R1, R2 and D1 are selected in combination with the balance cuts previously discussed. In one embodiment R1 is from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches) and most preferably about <NUM> (<NUM> inches); R2 is from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches) and most preferably about <NUM> (<NUM> inches); and <NUM> is from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches) and most preferably about <NUM> (<NUM> inches).

<FIG> further illustrate a second expression of the blade <NUM>. illustrated is a radius cut <NUM> in blade <NUM> to provide two back cutting edges <NUM> and 92a. As will be appreciated by the skilled artisan, radius cut <NUM> also provides a balance asymmetry within the functional symmetry to help balance the orthogonal modes. The back cutting edges <NUM> and 92a are positioned opposite the clamp pad <NUM> (<FIG>) to allow the surgeon to perform tissue cutting procedures without the assistance of the clamp pad <NUM>. Preferably, the radius cut is distal to the most distal tip of blade <NUM> to allow for a blunt radius tip for tissue dissection as discussed above. In one example of the second expression of blade <NUM>, a radius cut R3 is swept across an angle F measured at a distance D2 from the longitudinal axis and starting a distance <NUM> from the distal tip of blade <NUM>. In one embodiment R3 is from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches) and most preferably about <NUM> (<NUM> inches); angle F is from about <NUM>°to about <NUM>° and most preferably about <NUM>°; <NUM> is about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches) and most preferably about <NUM> (<NUM> inches); and <NUM> is from about <NUM> (<NUM> inches) to about <NUM> (<NUM> inches) and most preferably about <NUM> (<NUM> inches).

In a third expression of blade <NUM>, <FIG> illustrates a taper defined by angle O relative to an axis parallel to the longitudinal axis of waveguide <NUM> from the proximal end of blade <NUM> to the distal end of blade <NUM>. In one embodiment the taper may be on the blade surface that contacts tissue pad <NUM> (<FIG>). Alternatively, the taper may be the defined by the opposite surface comprising radius cut <NUM>. Referring to <FIG>, angle O ranges from about <NUM>° to about <NUM>°, and preferably from about <NUM>° to about <NUM>°.

Referring back to <FIG>, waveguide <NUM> is positioned within cavity <NUM> of handle assembly <NUM>. In order to properly locate the waveguide <NUM> both axially and radially, pin <NUM> extends through opening <NUM> of waveguide <NUM> (located at a node) and engages channel <NUM> (formed by the mating of housing portions <NUM> and <NUM>). Preferably pin <NUM> is made of any compatible metal, such as stainless steel or titanium or a durable plastic, such as polycarbonate or a liquid crystal polymer. In a first expression of one embodiment, pin <NUM> is partially coated with an elasto-meric material <NUM>, such as silicon for that portion <NUM> of pin <NUM> that extends through waveguide <NUM> and uncoated for that portion of pin <NUM> that engages members <NUM> and <NUM>. The silicone provides insulation from the vibrating blade throughout the. length of hole <NUM>. This enables high efficiency operation whereby minimal overheating is generated and maximum ultrasonic output power is available at the blade tip for cutting and coagulation. The lack of insulation allows pin <NUM> to be held firmly within handle assembly <NUM> due to the lack of insulation, which would provide deformation and movement if pin <NUM> were completely coated with an insulating material.

Referring now to <FIG> and <FIG> a first expression of clamp member <NUM> has a shaped slot <NUM> for accepting one or more tissue pads. This configuration prevents mis-loading of the tissue pads and assures that the appropriate pad is loaded at the correct location within clamp member <NUM>. For example clamp member <NUM> may comprise a T-shaped slot <NUM> to accept a T-shaped flange <NUM> of clamp pad <NUM>. Two mechanical stops <NUM> and 59a, when depressed, engage the proximal end of clamp pad <NUM> to secure the clamp pad within clamp member <NUM>. As would be appreciated by those skilled in the art, flanges and corresponding slots may have alternate shapes and sizes to secure the clamp pads to the clamp arm. The illustrated flange configurations shown are exemplary only and accommodate the particular clamp pad material of one embodiment, but the particular size and shape of the flange may vary, including, but not limited to, flanges of the same size and shape. For unitary tissue pads, the flange may be of one configuration. Further, other tab stops are possible and may include any of the multiple methods of mechanically attaching the clamp pads to the clamp arm, such as rivets, glue, press fit or any other fastening means well know to the artisan.

Referring to <FIG>, in a first expression of an alternate embodiment, clamp pad <NUM> consists of a first tissue pad 58b and a second pad portion 58a, which may be an insert within pad 58b. Tissue pad 58b may comprise a tissue engaging surface having saw tooth-like teeth and proximal portion 58a may have a smoother surface relative to pad 58b. The advantage of two separate components 58a and 58b is that each pad may be constructed from different materials. For example, having a two-piece tissue pad allows the use of a very lubricious material at the distal end that is not particularly resistant to high temperatures compared to a very high temperature material at the proximal end that is not particularly lubricious because the proximal end is an area of lower amplitude. Such a configuration matches the tissue pad materials to the amplitude of the blade <NUM>.

In a second expression of an alternate embodiment of the present disclosure, clamp pad 58b is formed from TEFLON® or any other suitable low-friction material. Clamp pad 58a is formed from a base material and at least one filler material, which is a different material from the base material. The surface of proximal clamp pad 58a may be smoother than distal clamp pad 58b, or proximal clamp pad 58a may also have a similar type saw-tooth configuration. Several benefits and advantages are obtained from one or more of the expressions of the disclosure.

Having a tissue pad with a base material and at-least-one filler material allows the base material and the at-least-one filler material to be chosen with a different hardness, stiffness, lubricity, dynamic coefficient of friction, heat transfer coefficient, abradability, heat deflection temperature, glass transition temperature and/or melt temperature to improve the wearability of the tissue pad, which is important when high clamping forces are employed because tissue pads wear faster at higher clamping forces than at lower clamping forces. In experiments, a <NUM>% graphite-filled polytetrafluoroethylene tissue pad showed substantially the same wear with a <NUM> (<NUM> pound) clamping force as a <NUM>% polytetrafluoroethylene tissue pad showed with a <NUM> (<NUM> pound) clamping force. Having a flexible clamping arm and/or a flexible tissue pad should also improve the wearability of the tissue pad due to the ability of the flexible member to more evenly distribute the load across the entire surface of the tissue pad. Further benefits and expressions of this embodiment are disclosed in <CIT> and commonly assigned to the assignee of the present application.

In a third expression of an alternate embodiment, a tissue pad with a base material and at least two filler materials allows the base material and the at-least-two filler materials to be chosen with a different hardness, stiffness, lubricity, dynamic coefficient of friction, heat transfer coefficient, abradability, heat deflection temperature, and/or melt temperature to improve the wearability of the tissue pad, which is important when high clamping forces are employed because tissue pads wear faster at higher clamping forces than at lower clamping forces. In experiments, a <NUM>% graphite-filled, <NUM>% PTFE-filled polyimide tissue pad showed substantially the same or better wear with a <NUM> (<NUM> pound) clamping force as a <NUM>% polytetrafluoroethylene tissue pad showed with a <NUM> (<NUM> pound) clamping force. The advantage of a <NUM>% graphite- filled, <NUM>% PTFE-filled polyimide tissue pad is increased heat resistance, which improves the overall wear resistance of the tissue pad. This polyimide- composite clamp pad has a useful heat resistance up about <NUM>°F to about <NUM>°F, as compared to a useful heat resistance up to about <NUM>°F of a PTFE clamp pad. Alternatively, other materials are also useful for a portion of the tissue pad, such as ceramics, metals, glasses and graphite.

<FIG> disclose a first expression of an embodiment of attaching a two part clamp pad 58a-b to a clamp member <NUM>. In <FIG>, at least two slots 57a and 57b are shaped to accept two correspondingly shaped flanges 55a and <NUM>'. In this example, T-slot 57a accepts a corresponding T-flange 55a of clamp pad 58a, and wedge-shaped slot <NUM>' accepts a corresponding wedge-shaped flange <NUM>' of clamp pad 58b.

<FIG> illustrate a second expression of attaching a clamp pad 58c to a clamp arm 56c. Clamp pad 58c comprises one or more protrusions <NUM> for insertion into one or more corresponding apertures <NUM> in clamp arm 56c. If a second or more clamp pad(s) 58d is also used in accordance with the previous discussion, then clamp pad 58c further comprises corresponding aperture <NUM> for accepting one or more clamp pad(s) 58d. Clamp arm 56c has corresponding aperture(s) <NUM> for accepting protrusions <NUM>, as well as a corresponding cavity <NUM> for accepting the one or more clamp pad 58d. <FIG> illustrates the components assembled together prior to staking. Clamp pad 58d fits inside the aperture <NUM> and cavity <NUM>, and pad 58c is aligned with clamp arm 56c so that protrusions <NUM> align with chamfered aperture <NUM>. Protrusions <NUM> have additional height beyond the top surface of clamp arm 56c to provide additional material to fill the chamfered volume during staking. Heat is applied to protrusions <NUM> above the clamp arm 56c; the protrusions deform and take the shape of the chamfered volume.

<FIG> illustrate a third expression of attaching a clamp pad 58d to a clamp arm 56d. In addition to a T-shaped flange <NUM>, clamp pad 58d further comprises a hook-like protrusion or clip <NUM> for attaching to a corresponding opening <NUM> at the distal tip of clamp arm 56d. In this expression, the distal tip of clamp arm 56d is open and the clamp pad 58d is inserted from the distal to proximal direction until the hook clip engages opening <NUM>. Hook clip <NUM> may be biased closed so when clip <NUM> engages opening <NUM>, clip <NUM> applies compressive forces against opening <NUM>.

A first expression for a method for inserting a clamp pad on a clamp arm includes a) inserting a first clamp pad having a first width dimension greater than a second width dimension and having a first-shaped flange into a clamp arm having a slot that accepts the first-shaped flange; and b) engaging a pad stop to secure the clamp pad within the clamp arm. In a second expression of the method, the clamp pad consists of a second clamp pad fabricated from a base material and at least one filler material, which is a different material from the base material. The second clamp pad may have a second-shaped flange for engaging a second-shaped slot on the clamp arm. The tissue surfaces of the clamp pads may be smooth or have tissue gripping features, such as a saw-tooth configuration.

A first expression for a method for replacing clamp pads would include the steps of: a) disengaging a pad stop; b) removing a first clamp pad from the clamp arm; c) removing a second clamp pad from the clamp arm, wherein at least one of the first or second clamp pads has a first width dimension greater than a second width dimension; d) inserting third and fourth clamp pads into the clamp arm wherein at least one of the third or fourth clamp pads has a first width dimension greater than a second width dimension ; and e) engaging a pad stop to secure the third and fourth clamp pads within the clamp arm. In a second expression of this method one of the third and fourth clamp pads may be fabricated from a polymeric material such as TEFLON, and the other clamp pad may be fabricated from a base material and at least one filler material, which is a different material from the base material. The tissue surfaces of the clamp pads may be smooth or have tissue gripping features, such as a saw-tooth configuration.

Referring to <FIG>, a clamp arm <NUM> is configured for use with the present ultrasonic surgical instrument <NUM> and for cooperative action with blade <NUM> and clamp member <NUM>. The clamp arm <NUM> is rotatably mounted to the distal end of outer shroud <NUM>, detailed below, and connectably attaches at the distal end of thumb ring or actuation member <NUM>. Clamp pad <NUM> mounts on the clamp member <NUM> for cooperation with blade <NUM>, with rotational movement of the clamp arm <NUM> positioning the clamp pad in substantially parallel relationship to, and in contact with, blade79, thereby defining a tissue treatment region. By this construction, tissue is grasped between clamp pad <NUM> and blade <NUM>. Pivotal movement of the clamp member <NUM> with respect to blade <NUM> is affected by the provision of a pair of camming members on the clamp arm <NUM> that interface with the outer shroud <NUM>. The outer shroud <NUM> is grounded to handle <NUM>.

A first expression of clamp arm <NUM> comprises jaw-carrying member 60a and mating member 60b. Jaw-carrying member 60a includes two camming members 94a and 94b for mating with two corresponding camming slots 95a and 95b located outer shroud <NUM>. Mating member 60b includes two camming members 96a and 96b for mating with two corresponding camming slots 97a and 97b located outer shroud <NUM>. Corresponding camming members 94a/94b and 96a/96b (and corresponding camming slots 95a/95b and 97a/97b) may align along common axes perpendicular to the longitudinal axis of waveguide <NUM> or camming members may be offset to facilitate the assembly process. Members 60a and 60b fixedly attach to each other as shown in <FIG> to form clamp arm <NUM> via press fit or snap fit. Other attaching methods are available as is known to those skilled in the art, such as welding, glue, screwing, etc. Once assembled, clamp arm <NUM> defines an opening <NUM> for receiving outer shroud <NUM> and the interlocking of the respective cam members and cam slots. Alternatively, members 60a and 60b may be assembly around outer shroud <NUM> and all three elements mated together in one operation. One benefit of the cam open and closure mechanism is that it can provide both a rotational motion and linear motion of the clamp arm <NUM> and clamp member <NUM> thereby providing better control of the pressure profile between clamp pad <NUM> and blade <NUM>.

In a second expression of clamp arm <NUM>, the camming members may be replaced with spherical elements that interface with cam slots. Alternatively camming members may be replaced with spherical depressions for receiving ball bearings that interface with the cam slots. Other camming mechanism would be useful as is well known to the skilled artisan.

With solid camming members and corresponding slots, the force delivered between the clamp pad <NUM> and blade <NUM> is directly related to the force that the user applies at the thumb ring <NUM> and finger ring <NUM>. In a third expression of clamp arm <NUM>, a force limiting element <NUM>, such as an elastomer or coil or leaf spring, may be inserted within one or more cam slots and provide a force limit to the coaptation force seen at the end effector <NUM>. Preferably, the spring constant of an elastomer or spring ranges from <NUM>-<NUM>/m (<NUM>-<NUM> Ib.

Outer shroud <NUM>, distal shroud <NUM> and clamp arm <NUM> may be constructed from any number of biocompatible materials, such as titanium, stainless steel or plastics. Preferably, however, these elements are constructed of either <NUM> or <NUM> T6 aluminum. The aluminum provides a large benefit in terms of heat dissipation. Devices of the prior art have sheaths and clamp arms made of stainless steel. Typical values for thermal conductivity for aluminum are around <NUM> W/m K. The values for stainless steel are around <NUM> W/m K. Thus, aluminum has approximately <NUM> times greater capability to transmit heat through the same amount of volume.

The inventors have found through testing of similar inputs (clamp force and blade displacement), the device of the present disclosure operates approximately <NUM> °F lower in temperature than instruments of the prior art. The aluminum components more effectively draw the heat away from the pad and the blade, thus keeping the end effector cooler than other prior art instruments. Referring now to <FIG>, <FIG> and <FIG> housing <NUM> includes a proximal end, a distal end, and a cavity <NUM> extending longitudinally therein. Cavity <NUM> is configured to accept a switch assembly <NUM> and the transducer assembly <NUM>. In one expression of the current embodiment, the distal end of transducer <NUM> threadedly attaches to the proximal end of transmission rod <NUM>. The distal end of transducer <NUM> also interfaces with switch assembly <NUM> to provide the surgeon with finger-activated controls on surgical instrument <NUM>.

Transducer <NUM> includes a first conductive ring <NUM> and a second conductive ring <NUM> which are securely disposed within the transducer body <NUM> as is described in co-pending application serial no. [ ] (Attorney docket no. END5747USNP2).

Switch assembly <NUM> comprises a pushbutton assembly <NUM>, a flex circuit assembly <NUM>, a switch housing <NUM>, a first pin conductor <NUM> and a second pin conductor <NUM>. Switch housing <NUM> is saddle-shaped and is supported within handle assembly <NUM> by way of corresponding supporting mounts on switch housing <NUM> and housing portions <NUM> and <NUM>. Housing <NUM> defines a first receiving area <NUM> for a dome switch, and a second receiving area <NUM> for a dome switch.

With particular reference now to <FIG>, pins <NUM> and <NUM> are electrically connected to dome switch <NUM> and <NUM> via conductors <NUM> and <NUM>, respectively, at one end and to the distal end of transducer <NUM> at a second end. Pins <NUM> and <NUM> each have a spring-loaded tip <NUM> and <NUM> that interface with transducer <NUM> as shown in <FIG>. Each end <NUM> and <NUM> have a <NUM> (<NUM> inch) working travel to allow for'manufacturing tolerances associated with the stackup of the assembled parts. Slidably attached to housing <NUM> are two triggers <NUM> and <NUM>, each comprising first and second halves 320a, 320a and 322a, 322b, respectively. Shown in Fig. <NUM> is trigger <NUM>, which comprises ridges 321a and band contact surface <NUM> (made up of mating surfaces 323a and 323b). When assembled, triggers <NUM> and <NUM> slidably attach to housing <NUM> and contact surfaces <NUM> and <NUM> mechanically engage dome switches <NUM> and <NUM>, respectively. Ridges <NUM> and <NUM> provide interface between the user and triggers <NUM> and <NUM>. Ridges <NUM> and <NUM> are designed to provide as much surface area for the user to depress in order to activate the instrument.

In a second expression of switch assembly <NUM> elastomeric connectors having copper traces etched onto the elastomer press fit into switch housing <NUM> to provide the electrical interconnect between transducer <NUM> and flex circuit <NUM>. One end of the elastomer connectors electrically engage dome swithches <NUM> and <NUM> via conductors <NUM> and <NUM>. The other end of the elastomer connectors slidably interface with conductors <NUM> and <NUM> of transducer <NUM>. Compression of the elastomer connectors allow a working travel of up to <NUM>% of the total height of the elastomer connectors to allow for manufacturing tolerances associated with the stackup of the assembled parts.

A flex circuit <NUM> provides for the electro-mechanical interface between pushbuttons <NUM> and <NUM> and the generator <NUM> via transducer <NUM>. Flex circuit comprises two dome switches <NUM> and <NUM> that are mechanically actuated by depressing pushbuttons <NUM> or <NUM> axially in the x direction. Dome switches <NUM> and <NUM> are electrical contact switches, that when depressed provide an electrical signal to generator <NUM> as shown by the electrical wiring schematic of <FIG>. Flex circuit <NUM> also comprises two diodes within a diode package <NUM> and conductors, <NUM> and <NUM> as is known to those in the art, that connect to pins <NUM> and <NUM>, respectively, which in turn provide electrical contact to ring conductors <NUM> and <NUM>, which in turn are connected to conductors in cable <NUM> that connect to generator <NUM>.

Flex circuit <NUM> generally sits within a channel <NUM> of switch assembly <NUM> so that dome switches <NUM> and <NUM> interface with the corresponding backing surfaces <NUM> and <NUM>. Backing surfaces provide a firm support for the dome switches during operation, discussed below. Dome switches <NUM> and <NUM> may be fixedly attached to backing surfaces <NUM> and <NUM> by any convenient method, such as, an adhesive.

As is readily apparent, by depressing pushbuttons <NUM> and <NUM> the corresponding contact surfaces <NUM> and <NUM> depress against corresponding dome switches <NUM> and <NUM> to activate the circuit illustrated in <FIG>. When the surgeon depresses <NUM> pushbutton, the generator will respond with a certain energy level, such as a maximum ("max") power setting; when the surgeon depresses pushbutton <NUM>, the generator will respond with a certain energy level, such as a minimum ("min") power setting, which conforms to accepted industry practice for pushbutton location and the corresponding power setting.

Referring now to <FIG>, the pushbutton axial actuation reduces stress on the surgeon's fingers and allows the fingers to actuate force in a more ergonomic position preventing stresses at the hands and wrists. The switch movement also allows comfortable button activation in less than optimal hand positions, which surgeons often encounter throughout a typical procedure.

At the proximal end of each access ring <NUM> and <NUM> are protrusions <NUM> and <NUM>, respectively, that allow the surgeon to rest his or her pinky finger for added control and comfort. This also allows the surgeon to use the pinky when clamping on tissue, thereby reducing the force on the other fingers. Each access ring <NUM> and <NUM> includes a soft-touch surface on the interior and exterior surfaces whether by inserting fingers into the access rings or palming the access rings. This feature allows a greater number of hand sizes to comfortably use the device.

Referring to <FIG>, access rings <NUM> and <NUM> define a length L. Perferably, the center of gravity of the surgical instrument <NUM> in combination with the transducer <NUM> is positioned within length L, more preferably within length L1, and most preferably within length L2. This position of the center of gravity allows the instrument to balance within the surgeon's hand to provide more precise control of the instrument and eliminate hand fatigue during procedures.

Referring now to <FIG> and <FIG>, a two-piece torque wrench <NUM> is shown. The torque wrench includes a hand wrench <NUM> and an adaptor <NUM>. In one embodiment, hand wrench <NUM> is provided with cantilever arms <NUM> disposed in an annular fashion about the centerline of hand wrench <NUM>. Cantilever arms <NUM> include teeth 501a disposed, in one embodiment, in an inward perpendicular fashion in relation to cantilever arms <NUM>. Teeth 501a, in one embodiment of the current disclosure, are disposed with a cam ramp 501b at a <NUM>° angle with respect to the perpendicular angle between arm <NUM> and teeth 501a. Lumen <NUM> extends the entire length of hand wrench <NUM> for accepting adaptor <NUM>.

Adaptor <NUM> has a longitudinal shaft <NUM> with cantilevered tabs <NUM> at its distal end. At the proximal end of shaft <NUM> are spline gears <NUM> projecting in a perpendicular fashion along the outer circumference of shaft <NUM>. Spline gears <NUM> include cam ramps 556a disposed at an angle from about <NUM>° to about <NUM>° with respect to the perpendicular angle between the outer circumference of shaft <NUM> and spline gears <NUM>. Shaft <NUM> further defines a lateral opening (not shown) proximal to spline gears <NUM> for accepting curved blade <NUM>, discussed below. Adaptor further includes an interface <NUM> rigidly connected to shaft <NUM> and defining an opening for rigidly engaging the distal end of instrument <NUM>. Optionally, a skirt <NUM> surrounds spline gears <NUM> to prevent glove snags due to moving parts and forms a cavity <NUM>.

In assembly, torque wrench opening <NUM> is aligned with shaft <NUM> and guided along substantially the entire length of shaft <NUM> until the tabs <NUM> flex inward and capture shoulder <NUM> (not shown) at the distal end of hand wrench <NUM>. Hand wrench lip <NUM> engages the distal end of optional skirt <NUM> allowing cantilever teeth 501a to slidably engage spline gears <NUM>. Cam ramp 501b slidably engages retainer cam ramps 29b. The torque wrench assembly <NUM> slidably engages the distal end of instrument <NUM> and is held rigidly in place. Flat surfaces 560b and 560a of interface <NUM> mate with flat surfaces 565b (<FIG>) and 565a (not shown) at the distal end of activation member <NUM> (clamp arm <NUM>) and rail <NUM> slidably engaging slot <NUM> on clamp arm <NUM> and distra shroud <NUM> and outer shroud <NUM> all provide structural support to maintain adapter <NUM> firmly engaged with instrument <NUM>.

Clockwise annular motion or torque is imparted to hand wrench <NUM> through paddles <NUM>. The torque is transmitted through arms <NUM> and teeth 501a to gears <NUM>, which in turn transmit the torque to the waveguide <NUM> via clamp arm assembly <NUM> via outer shroud <NUM> via insulated pin <NUM>. When a user imparts <NUM>-<NUM> (<NUM>-<NUM> Ibs. ) of torque, the ramps 501b and <NUM> cause the arms <NUM> to move or flex away from the centerline of wrench <NUM> ensuring that the user does not over-tighten the waveguide <NUM> onto transducer <NUM>. When a counter- clockwise torque is applied to wrench <NUM> via paddles <NUM>, the perpendicular flat sides of teeth 501a and <NUM> abut allowing a user to impart a torque to the interface between the waveguide <NUM> and transducer <NUM> in proportion to the force applied to the paddles facilitating removal of the instrument <NUM> from the transducer <NUM>. The torque wrench <NUM> may be constructed from a durable plastic, such as polycarbonate or a liquid crystal polymer. It is also contemplated that the wrench <NUM> may alternatively be made from a variety of materials including other plastics, ceramics or metals.

In another embodiment (not shown), the paddles and cantilever arm assembly may be separate components attached by mechanical means or chemical means such as adhesives or glue.

Claim 1:
An ultrasonic surgical instrument (<NUM>) comprising:
a scissor grip handle assembly (<NUM>), wherein the scissor grip handle assembly comprises:
a thumb ring (<NUM>);
a finger ring (<NUM>); and
a housing (<NUM>, <NUM>) defining a longitudinal axis and having a cavity (<NUM>) extending longitudinally therein, the cavity (<NUM>) for accepting a transducer (<NUM>), wherein the finger ring (<NUM>) is fixedly attached to the housing (<NUM>, <NUM>);
a shroud (<NUM>) attached to the distal-most end of the housing (<NUM>, <NUM>);
a clamp arm (<NUM>) connectably attached at the distal end of the thumb ring and rotatably mounted to the distal end of the shroud (<NUM>);
a first switch (<NUM>) positioned on the housing and slidably attached thereto for actuation by one or more fingers of a user in a direction parallel to the longitudinal axis and further electrically connectable to a generator (<NUM>) for providing an electrical signal to the generator for controlling a first level of ultrasonic energy delivered by the transducer.