Surgical instrument with stamped double-flag jaws

[0051] Referring initially to FIG. 1, an embodiment of an electrosurgical forceps 400 generally includes a housing 412 that supports various actuators thereon for remotely controlling an end effector 414 through an elongated shaft 416. Although this configuration is typically associated with instruments for use in laparoscopic or endoscopic surgical procedures, various aspects of the present disclosure may be practiced with traditional open instruments and in connection with endoluminal procedures as well.

-9CA 02813637 2013-04-23

[0052] The housing 412 is constructed of a left housing half 412a and a right housing half 412b. The left and right designation of the housing halves 412a, 412b refer to the respective directions as perceived by an operator using the forceps 400. The housing halves 412a, 412b may be constructed of sturdy plastic, and may be joined to one another by adhesives, ultrasonic welding or other suitable assembly methods.

[0053] To mechanically control the end effector 414, the housing 412 supports a stationary handle 420, a movable handle 422, a trigger 426 and a rotation knob 428. The movable handle 422 is operable to move the end effector 414 between an open configuration (FIG. 2A) wherein a pair of opposed jaw members 430, 432 are disposed in spaced relation relative to one another, and a closed or clamping configuration (FIG. 2B) wherein the jaw members 430, 432 are closer together. Approximation of the movable handle 422 with the stationary handle 420 serves to move the end effector 414 to the closed configuration and separation of the movable handle 422 from the stationary handle 420 serves to move the end effector 414 to the open configuration. The trigger 426 is operable to extend and retract a knife blade 456 (see FIGS. 2A and 2B) through the end effector 414 when the end effector 414 is in the closed configuration. The rotation knob 428 serves to rotate the elongated shaft 416 and the end effector 414 about a longitudinal axis A-A extending through the forceps.

[0054] To electrically control the end effector 414, the housing 412 supports a switch 436 thereon, which is operable by the user to initiate and terminate the delivery of electrosurgical energy to the end effector 414. The switch 436 is in electrical communication with a source of electrosurgical energy such as electrosurgical generator 440 or a battery (not shown) supported within the housing 412. The generator 440 may include devices such as the LIGASURE® Vessel Sealing Generator and the Force Triad® Generator as sold by Covidien Energy-based

-10CA 02813637 2013-04-23

Devices of Boulder, Colorado. A cable 442 extends between the housing 412 and the generator 440 and may include a connector (not shown) thereon such that the forceps 400 may be selectively coupled and decoupled electrically from the generator 440.

[0055] Referring now to FIGS. 2A - 3, the end effector 414 may be moved from the open configuration (FIG. 2A) wherein tissue (not shown) is received between the jaw members 430, 432, and the closed configuration (FIG. 2B), wherein the tissue is clamped and sealed. Upper jaw member 430 and lower jaw member 432 are mechanically coupled to the elongated shaft 416 about a pivot pin 444. The upper and lower jaw members 430, 432 are electrically coupled to cable 442, and thus to the generator 440 (e.g., via a respective wire extending through the elongated shaft 416) to provide an electrical pathway to a pair of electrically conductive, tissueengaging sealing plates 448, 450 disposed on the lower and upper jaw members 432, 430, respectively. A pair of wire conduits 478a and 478b may be provided to guide wires proximally from the end effector 414. The wire conduits 478a and 478b may be constructed of a plastic tube, and serve to protect wires from sharp edges that may form on surrounding components. The sealing plate 448 of the lower jaw member 432 opposes the sealing plate 450 of the upper jaw member 430, and, in some embodiments, the sealing plates 448 and 450 are electrically coupled to opposite terminals, e.g., positive or active (+) and negative or return (-) terminals associated with the generator 440. Thus, bipolar energy may be provided through the sealing plates 448 and 450. Alternatively, the sealing plates 448 and 450 and/or the end effector 414 may be configured for delivering monopolar energy to the tissue. In a monopolar configuration, the one or both sealing plates 448 and 450 deliver electrosurgical energy from an active terminal, e.g. (+), while a return pad (not shown) is placed generally on a patient and provides a return path to the opposite terminal, e.g. (—), of the generator 440.

-11CA 02813637 2013-04-23

[0056] The jaw members 430, 432 may be pivoted about the pivot pin 444 to move the end effector 414 to the closed configuration of FIG. 2B wherein the sealing plates 448, 450 provide a pressure to tissue grasped therebetween. In some embodiments, to provide an effective seal, a pressure within a range between about 3 kg/cm² to about 16 kg/cm² and, desirably, within a working range of 7 kg/cm² to 13 kg/cm² is applied to the tissue. Also, in the closed configuration, a separation or gap distance “G” may be maintained between the sealing plates 448, 450 by an array of stop members 454 (FIG. 2A) disposed on or adjacent the sealing plates 448, 450. The stop members 454 contact opposing surfaces on the opposing jaw member 430, 432 and prohibit further approximation of the sealing plates 448, 450. In some embodiments, to provide an effective tissue seal, an appropriate gap distance of about 0.001 inches to about 0.010 inches and, desirably, between about 0.002 and about 0.005 inches may be provided. In some embodiments, the stop members 454 are constructed of an electrically non-conductive plastic or other material molded onto the jaw members 430, 432, e.g., by a process such as overmolding or injection molding. In other embodiments, the stop members 454 are constructed of a heat-resistant ceramic deposited onto the jaw members 430, 432. Other methods of controlling gap are contemplated including those described in the commonly assigned patent application entitled GAP CONTROL VIA OVERMOLD TEETH AND HARD STOPS (Application No. 13/835004).

[0057] Electrosurgical energy may be delivered to the tissue through the electrically conductive seal plates 448, 450 to effect a tissue seal. Once a tissue seal is established, a knife blade 456 may be advanced through a knife channel 458 defined in one or both jaw members 430, 432 to transect the sealed tissue. Knife blade 456 is depicted in FIG. 2A as extending from the elongated shaft 416 when the end effector 414 is in an open configuration. In some

-12CA 02813637 2013-04-23 embodiments, a knife lockout is provided to prevent extension of the knife blade 456 into the knife channel 458 when the end effector 414 is in the open configuration, thus preventing accidental or premature transection of tissue and avoiding safety concerns.

[0058] Referring now to FIG. 3 A, the elongated shaft 416 includes various longitudinal components that operatively couple the end effector 414 to the various actuators supported by the housing 412 (FIG. 1). An outer shaft member 460 defines an exterior surface of the elongated shaft 416 and supports movement of other components therethrough as described below. The outer shaft member 460 may be constructed from a flat stock piece of metal. In constructing the outer shaft member 460, a stamping, punching or similar metal-working process may be employed to initially generate a flat blank that includes an appropriate outer profile and any interior openings or features. Thereafter, the necessary bends and curves may be formed by bending the flat blank with a press brake, or other suitable metal-working equipment The outer shaft member 460 may be formed by folding the flat blank into a generally circular profile (or generally rectangular profile) such that two opposing longitudinal edges of the flat blank meet at a longitudinal seam (not explicitly shown). Although the longitudinal seam does not necessarily require joining by a mechanical interlock or any other suitable process, the seam may, in some embodiments, be joined by laser welding (or other suitable process) to form a continuous circular or other geometric (e.g., rectangular) profile. The seam may be generally straight, or alternatively, a box joint, a dovetail joint, or any other suitable interface known in the metalworking arts.

[0059] The outer shaft member 460 defines a clevis 464 at a distal end thereof for receiving the jaw members 430 and 432. Opposing vertical sidewalls 464a and 464b of the outer shaft member 460 include respective bores 466a, 466b extending therethrough to frictionally

-13CA 02813637 2013-04-23 support the pivot pin 444 and maintain an orientation of the pivot pin 444 with respect to the outer shaft member 460. Alternatively or additionally, the pivot pin 444 may be fastened to the outer shaft member 460 by a laser or heat-based welding, adhesives, chemical bonding, or other suitable manufacturing processes.

[0060] At a proximal portion of the outer shaft member 460, various features are provided that serve to couple the outer shaft member 460 to various elements of the housing 412. More specifically, the proximal portion of the outer shaft member 460 includes, in order from distal to proximal, a series of tabs 486 extending therefrom, a washer 499 extending around outer shaft member 460, a pair of opposing longitudinal slots 468a, 468b defined therethrough and provided to allow longitudinal translation of a dowel pin 493 therethrough, and a longitudinal slot 469 extending distally from a proximal end thereof to couple the outer shaft member 460 to the rotation knob 428. The connection established between the outer shaft member 460 and the rotation knob 428 is described below with reference to FIG. 4. As shown in FIGS. 15A - 15D, the series of tabs 486 and the washer 499 serve to aid in securing the proximal portion of the outer shaft member 460 within the housing 412.

[0061] The pivot pin 444 extends through a proximal portion of each of the jaw members 430, 432 to pivotally support the jaw members 430, 432 at the distal end of the outer shaft member 460. With reference to FIG. 8, a proximal portion of each of the jaw members 430, 432 is configured as a “double flag.” The double flag configuration refers to the two laterally spaced parallel flanges or “flags” 430a, 430b and 432a, 432b respectively, extending proximally from a distal portion of the jaw members 430 and 432. A lateral cam slot 430c and a lateral pivot bore 430d extend through each of the flags 430a, 430b of the upper jaw member 430. Similarly, a lateral cam slot 432c and a lateral pivot bore 432d extend through each of the flags 432a, 432b of

-14CA 02813637 2013-04-23 the lower jaw member 432. The pivot bores 430d, 432d receive the pivot pin 444 in a slip-fit relation that permits the jaw members 430, 432 to pivot about the pivot pin 444 to move the end effector 414 between the open and closed configurations (FIGS. 2A and 2B, respectively).

[0062] An inner shaft member 480 is received within the outer shaft member 460 and is configured for longitudinal motion with respect to the outer shaft member 460. A distal knife guide 486 includes sidewalls 482a, 482b and a proximal key slot 487 that supports a key member 494 therethrough. During assembly of electrosurgical forceps 400, the distal knife guide 486 is slid proximally within a distal end of the inner shaft member 480, such that the inner shaft member 480 surrounds a portion of the distal knife guide 486, and opposing lateral sides of the key member 494 align with and fit within opposing longitudinal key slots 495a, 495b defined through the inner shaft member 480 to couple the knife guide 486 to the inner shaft member 480 (FIG. 3B). The inner shaft member 480 includes a pair of opposing longitudinal slots 472a, 472b extending proximally from a distal end of the inner shaft member 480 along a portion of the inner shaft member 480 between the opposing longitudinal key slots 495a, 495b. The longitudinal slots 472a, 472b allow the distal end of the inner shaft member 480 to aid in sliding of the distal knife guide 486 proximally within the inner shaft member 480. Once the key member 494 is aligned with and fit within the longitudinal key slots 495a, 495b, the key member 494 effectively couples the distal knife guide 486 to the inner shaft member 480, as depicted by FIG. 3B.

[0063] The sidewalls 482a, 482b define a longitudinal slot 483 through the distal knife guide 486 that provides lateral support to the knife 402. The knife 402 is substantially surrounded at a distal end thereof by the distal knife guide 486 on four lateral sides and the sidewalls 482a, 482b of the distal knife guide 486 constrain side-to-side lateral motion of the

-15CA 02813637 2013-04-23 knife 402. Thus, the distal knife guide 486 serves to urge the knife 402 into a central position within the elongated shaft 416, thereby ensuring proper alignment of the knife 402 as the knife 402 reciprocates within knife channel 458 (FIG. 2A). The distal knife guide 486 includes features for operatively coupling the inner shaft member 480 to the end effector 414. A proximal portion 488 of the inner shaft member 480 is configured for receipt within the housing 412 (FIG. 1), and includes features for operatively coupling the inner shaft member 480 to the actuators supported thereon, e.g. the movable handle 422.

[0064] The distal knife guide 486 includes a through bore 490 extending through the sidewalls 482a, 482b for receiving the cam pin 492. Distally of the through bore 490, a longitudinal slot 496 is defined through the sidewalls 482a, 482b. The longitudinal slot 496 provides clearance for the pivot pin 444, and thus, permits longitudinal reciprocation of the inner shaft member 480 independent of the pivot pin 444.

[0065] The proximal portion 488 of the inner shaft member 480 includes, in order from distal to proximal, a pair of opposing longitudinal knife slots 488a, 488b extending therethrough, a pair of opposing distal locking slots 481a, 481b extending therethrough, a pair of opposing proximal locking slots 471a, 471b extending therethrough, and a proximal end 491 configured to engage a suitable mechanical interface within the housing 412 to aid in proper support of the inner shaft member 480 within the housing 412 (see FIGS. 12 and 15A - 15D).

[0066] The knife 402 is a generally flat, metal component defining a profile that may be constructed by a stamping process. The knife 402 supports the sharpened knife blade 456 at a distal-most end thereof. The sharp edge of the knife blade 456 may be applied to the distal end of the knife 402 subsequent to the stamping process that forms the profile. For example, various manufacturing techniques may be employed such as grinding, coining, electrochemical etching,

-16CA 02813637 2013-04-23 electropolishing, or other suitable manufacturing processes, for forming sharpened edges. A longitudinal slot 406 is defined within the knife 402 to provide clearance for the pivot pin 444, the cam pin 492, and the key member 494. A proximal through bore 408a extends through a proximal portion 408 of the knife 402 and provides a mechanism for operatively coupling the knife 402 to the trigger 426 via the dowel pin 493. The connection between the knife 402 and the trigger 426 is described in detail below with reference to FIGS. 12, 13, 14A, and 14B.

[0067] Referring now to FIG. 4, the rotation knob 428 includes a passageway 429 defined therethrough for receiving the outer shaft member 460. The passageway 429 has a generally circular profile corresponding to the circular profile of the outer shaft member 460. The passageway 429 includes a longitudinal keying member 414 that is configured to align with and be seated within longitudinal slot 469 (FIG. 3A) of the outer shaft member 460. The keying member 414 projects laterally inward along the length of passageway 429 such that the insertion of the proximal end of the outer shaft member 460 into the passageway 429 of the rotation knob 428 operatively couples the outer shaft member 460 to the rotation knob 428 and, thus, permits longitudinal motion of the inner shaft member 480 therethrough.

[0068] In one embodiment, a cable clearance passageway (not shown) is defined through rotation knob 428 to permit passage of electrical cables or wires that electrically couple the sealing plates 448, 450 to the electrosurgical generator 440 (FIG. 1). Rotational motion imparted to the rotation knob 428 may thus impart rotational motion to each of the components of the elongated shaft 416, and to the end effector 414, which is coupled thereto.

[0069] As shown in FIG. 13, the rotation knob 428 is seated within an interior compartment 434 of the housing 412 and, as shown in FIG. 1, extends laterally outward from opposing sides of the housing 412 (only shown extending laterally outward from housing half

-17CA 02813637 2013-04-23

412b). The interior compartment 434 defines distal and proximal passageways 434a and 434b that permit the passage of the components of the elongated shaft 416 therethrough. The rotational motion of the rotation knob 428 may be limited by a stop boss 430 projecting distally from the rotation knob 428 (FIG. 4). The stop boss 430 is positioned to engage the distal passage 434a of the compartment 434 to restrict rotational motion of the rotation knob 428. For example, in some embodiments, the stop boss 430 may engage the distal passage 434a to restrict rotational motion of the rotation knob 428 to 180 degrees in either direction.

[0070] Referring now to FIG. 5, the end effector 414 is coupled to the distal end of the elongated shaft 416 by the pivot pin 444. The pivot pin 444 is coupled to the sidewalls 464a and 464b of the clevis 464 defined at the distal end of the outer shaft member 460. Thus, the pivot pin 444 represents a longitudinally stationary reference for the longitudinal movements of inner shaft member 480 and the knife 402. Laterally inward of the sidewalls 464a, 464b, the pivot pin 444 extends through the flags 432a, 432b of the lower jaw member 432, the flags 430a and 430b of the upper jaw member 430, the sidewalls 482a, 482b of the knife guide 486, and the knife 402. The jaw members 430, 432 are free to pivot about the pivot pin 444, and the inner shaft member 480 and the knife 402 are free to translate longitudinally around the pivot pin 444.

]0071] Referring now to FIG. 6, the end effector 414 is shown in the open configuration. Since the knife guide 486 is coupled to the cam pin 492, when the inner shaft member 480 is in the distal position, the cam pin 492 is located in a distal position in cam slots 430c and 432c defined through the flags 430a, 430b, 432a, 432b of the jaw members 430,432, respectively.

[0072] The inner shaft member 480 may be drawn proximally relative to the pivot pin 444 to move the end effector 414 to the closed configuration (see FIG. 2B). Since the longitudinal position of the pivot pin 444 is fixed (by the outer shaft member 460, which is

-18CA 02813637 2013-04-23 removed from view in FIG. 6 for clarity), and since the cam slots 430c, 432c are obliquely arranged with respect to the longitudinal axis A-A, proximal retraction of the cam pin 492 through the cam slots 430c, 432c induces the jaw members 430, 432 to pivot toward one another about the pivot pin 444. Conversely, when the end effector 414 is in the closed configuration, longitudinal translation of the inner shaft member 480 in a distal direction induces the jaw members 430, 432 to pivot away from one another toward the open configuration.

[0073] Referring now to FIG. 7, the longitudinal slot 406 in the knife 402 extends around both the pivot pin 444 and the cam pin 492, and thus the pins 444, 492 do not interfere with the reciprocal motion of the knife 402. The pivot pin 444 and cam pin 492 extend through the slot 406 in such a manner as to guide longitudinal motion of the knife 402 as well as constrain vertical motion of the knife 402. The blade 456 at the distal-most end of the knife 402 is centrally aligned by the knife guide 486, as discussed hereinabove. Properly aligned, the blade 456 readily enters the knife channel 458 defined in the jaw members 430, 432.

[0074] Referring now to FIGS. 8 and 9, the lower jaw member 432 is constructed of three major components. These components include a double-flag jaw insert 440, an insulator 442 and the sealing plate 448. The flags 432a, 432b of the jaw member 432 define a proximal portion of the double-flag jaw insert 440, and a generally u-shaped channel 444 extends distally to support the tissue engaging portion of the jaw member 432. The double-flag jaw insert 440 includes various planar surfaces, and may be constructed as a sheet metal component formed by a stamping process. In such a stamping process, the cam slots 432c and pivot holes 432d may be punched into a flat blank, and subsequently the blank may be bent to form the flags 432a, 432b and the u-shaped channel 444.

-19CA 02813637 2013-04-23

[0075] The insulator 442 may be constructed of an electrically insulative plastic such as a polyphthalamide (PPA) (e.g., Amodel®), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), a blend of PC and ABS, nylon, ceramic, etc. The electrically insulative plastic may be overmolded onto the jaw insert 440 in a single-shot injection molding process such that sealing plate 448 is overmolded to the jaw insert 440. Additionally or alternatively, the electrically insulative plastic may be mechanically coupled to the jaw insert 440, e.g., pressed, snapped, glued, etc. Various features may be molded into the insulator 442 that facilitate the attachment of the sealing plate 448 to the insert 440. For example, tabs may be provided that permit a snapfit attachment of the sealing plate 448, or ridges may formed that permit ultrasonic welding of the sealing plate 448 onto the insulator 442. The sealing plate 448 may be constructed of an electrically conductive metal, and may be stamped from a flat sheet stock.

[0076] Referring now to FIG. 10, the flags 430a, 430b of the upper jaw member 430 are depicted schematically in a nestled configuration with respect to the flags 432a, 432b of the lower jaw member 432. The proximal portion of the upper jaw member 430 is narrower than the proximal portion of the lower jaw member 432, and thus, a lateral spacing “S” between the flags 432a, 432b is sufficient to permit the flags 430a and 430b to be positioned therebetween. A pivot axis “Po” extends through an overlapping portion of the flags 430a, 432a, and 430b, 432a such that the upper and lower jaw members 430, 432 may pivot about the common axis “Po ” In the nestled configuration, the proximal portions of the upper and lower jaw members 430, 432 also share a common centerline “CL - 1” that is transverse with respect to the pivot axis “Po·”

[0077] An alternative to the nestled configuration illustrated in FIG. 10 is the offset configuration illustrated schematically in FIG. 11. A proximal portion of double-flag upper jaw member 450 includes flags 450a and 450b. A proximal portion of a double-flag lower jaw

-20CA 02813637 2013-04-23 member 452 includes flags 452a and 452b and exhibits a width that is identical to a width of the proximal portion of the upper jaw member 450. To provide an overlapping portion of the flags 450a, 452a and 450b, 452b such that the jaw members 450, 452 may pivot about the common axis “Po,” one flag 450a of the upper jaw member 450 is positioned on a laterally exterior side of the corresponding flag 452a of the lower jaw member 452, and the other flag 450b of the upper jaw member 450 is positioned on a laterally interior side of the corresponding flag 452b of the lower jaw member 452. In the offset configuration, a centerline “CL - 2” of the proximal portion of the upper jaw member 450 is laterally offset with respect to a centerline “CL - 3” of the lower jaw member 452.

[0078] Referring now to FIG. 12, the connection of the movable handle 422 and the knife trigger 426 to the longitudinally movable components of the elongated shaft 416 is described. The movable handle 422 may be manipulated to impart longitudinal motion to the inner shaft member 480, and the knife trigger 426 may be manipulated to impart longitudinal motion to the knife 402. As discussed above, longitudinal motion of the inner shaft member 480 serves to move the end effector 414 between the open configuration of FIG. 2A and the closed configuration of FIG. 2B, and longitudinal motion of the knife 402 serves to move knife blade 456 through knife channel 458 (FIG. 2A).

[0079] The movable handle 422 is operatively coupled to the inner shaft member 480 by a connection mechanism 476 (FIG. 12). The connection mechanism 476 includes a clevis 478 defined at an upper end of the movable handle 422. The clevis 478 is pivotally supported on the left housing half 412b by a pivot boss 479. A second complementary pivot boss (not shown) is provided on the right housing half 412a to support the clevis 478. Each of two upper flanges 478a and 478b of the clevis 478 extend upwardly about opposing sides of a drive collar 484

-21CA 02813637 2013-04-23 supported on the inner shaft member 480 and include rounded drive surfaces 497a and 497b thereon. Drive surface 497a engages a proximal-facing surface of a distal lock collar 484a and drive surface 497b engages a distal facing surface of a proximal rim 484b of the drive collar 484 (FIG. 13). The distal lock collar 484a engages the opposing distal locking slots 481a, 481b (FIG. 3A) extending through the proximal portion 488 of the inner shaft member 480 to lock-fit the distal lock collar 484a to the inner shaft member 480. Thus, the distal lock collar 484a is prevented from longitudinal motion relative to the inner shaft member 480. Drive surface 497a is arranged along the longitudinal axis A-A such that pivotal motions of the movable handle 422 about the pivot bosses 479 induce corresponding longitudinal motion of the drive collar 484 along the longitudinal axis A-A in the proximal direction. Drive surface 497b is arranged along the longitudinal axis A-A such that pivotal motions of the movable handle 422 about the pivot bosses 479 induce corresponding longitudinal motion of the distal lock collar 484a along the longitudinal axis A-A in the distal direction.

[0080] Referring now to FIG. 13, proximal longitudinal motion may be imparted to the inner shaft member 480 by pushing the proximal rim 484b of the drive collar 484 proximally with the movable handle 422 (FIG. 12) as indicated by arrow D4. The proximal rim 484b engages a spring 489 that is constrained between the proximal rim 484b and a proximal lock collar 415. The proximal lock collar 415 engages the opposing proximal locking slots 471a, 471b (FIG. 3 A) extending through the proximal portion 488 of the inner shaft member 480 to lock-fit the proximal lock collar 415 to the inner shaft member 480. Thus, the proximal lock collar 415 is prevented from longitudinal motion relative to the inner shaft member 480 and serves as a proximal stop against which spring 489 compresses.

-22CA 02813637 2013-04-23

[0081] Distal longitudinal motion is imparted to the inner shaft member 480 by pushing the distal lock collar 484a distally with drive surface 497a of movable handle 422 as indicated by arrow D3 (FIG. 13). Distal longitudinal motion of the distal lock collar 484a induces a corresponding distal motion of the inner shaft member 480 by virtue of the lock-fit coupling of the distal lock collar 484a to the opposing proximal locking slots 471a, 471b extending through the proximal portion 488 of the inner shaft member 480 (FIG. 3A).

[0082] Proximal longitudinal motion of the inner shaft member 480 draws the cam pin 492 proximally to pivot the jaw members 430, 432 toward one another to move the end effector 414 to the closed configuration as described above with reference to FIG. 6. Once the jaw members 430 and 432 are closed, the inner shaft member 480 essentially bottoms out (i.e., further proximal movement of the inner shaft member 480 is prohibited since the jaw members 430, 432 contact one another). Further proximal movement of the movable handle 422 (FIG. 12), however, will continue to move the drive collar 484 proximally. This continued proximal movement of the drive collar 484 further compresses the spring 489 to impart additional force to the inner shaft member 480, which results in additional closure force applied to tissue grasped between the jaw members 430, 432 (see FIG. 2B). The spring 489 also serves to bias the movable handle 422 to an open configuration such that the movable handle 422 is separated from the stationary handle 420.

[0083] Referring again to FIG. 12, the trigger 426 is pivotally supported in the housing 412 about a pivot boss 403 protruding from the trigger 426. The trigger 426 is operatively coupled to the knife 402 by a knife connection mechanism 404 such that pivotal motion of the trigger 426 induces longitudinal motion of the knife 402. The knife connection mechanism 404 includes upper flanges 426a, 426b of the trigger 426 and a knife collar 410.

-23CA 02813637 2013-04-23

[0084] Referring now to FIGS. 13, 14A, and 14B, the knife collar 410 includes a cap member 411 coupled thereto and a pair of integrally formed pin bosses 439a, 439b extending from opposing sides thereof. The knife collar 410 may include indentations or catches defined therein (not shown) that receive corresponding snap-in features (e.g., arms) of the cap member 411. The cap 411 may thus be assembled to the knife collar 410 such that the cap 411 and the knife collar 410 translate together. As shown by FIG. 14B, the coupling of the knife collar 410 to the cap 411 forms an interior circular channel 413 to capture the dowel pin 493 therein such that the dowel pin 493 is supported on opposing ends between the knife collar 410 and the cap 411. The dowel pin 493 extends through the proximal through bore 408a extending through a proximal portion 408 of the knife 402 (FIG. 3A) to operably couple the knife 402 to the knife collar 410. Upon longitudinal motion of the inner shaft member 480, dowel pin 493 translates longitudinally within knife slots 488a, 488b, respectively, of the inner shaft member 480 such that the longitudinal motion of inner shaft member 480 is unimpeded by dowel pin 493. Upon rotation of the elongated shaft 416 and end effector 414 about the longitudinal axis A-A via the rotation knob 428 (FIG. 1), dowel pin 493 freely rotates within the interior circular channel 413 such that the outer and inner shaft members 460 and 480 (removed from view in FIG. 14B for clarity), the knife 402, and the dowel pin 493 rotate within the knife collar 410 about the longitudinal axis A-A. In this way, the knife collar 410 serves as a stationary reference for the rotational movement of the outer shaft member 460, the inner shaft member 480, the knife 402, and the dowel pin 493.

[0085] Referring again to FIG. 12, the upper flanges 426a, 426b of the trigger 426 include respective slots 427a, 427b defined therethrough that are configured to receive the pin bosses 439a, 439b, respectively, of the knife collar 410 such that pivotal motion of the trigger

-24CA 02813637 2013-04-23

426 induces longitudinal motion of the knife collar 410 and, thus, the knife 402 by virtue of the coupling of knife 402 to the knife collar 410 via the dowel pin 493 extending through the through bore 408a. During longitudinal motion of the knife collar 410, dowel pin 493 translates longitudinally within the opposing slots 468a, 468b of the outer shaft member 460 and the slots 488a, 488b of the inner shaft member 480.

[0086] Referring now to FIGS. 13 and 14A, when the trigger 426 is moved to induce motion of the knife collar 410 in order to translate the blade 456 through the knife channel 458, the knife collar 410 translates along the outer shaft member 460 in the direction of arrow A9 to abut a spring 419 such that spring 419 compresses against a distal portion 421 of the interior of the housing 412 (FIG. 12). The spring 419 biases the knife collar 410 in a proximal direction to a proximal position along the outer shaft member 460.

[0087] Referring now to FIGS. 15A, 15B, 15C and 15D, a sequence of motions may be initiated by moving the movable handle 422 to induce motion of the jaw drive mechanism in order to close the jaws 430, 432, and by moving the trigger 426 to induce motion of the knife collar 410 in order to translate the blade 456 through the knife channel 458. Initially, both the moveable handle 422 and the knife trigger 426 are in a distal or un-actuated position as depicted in FIG. 15A. This arrangement of the moveable handle 422 and trigger 426 sustains the end effector 414 in the open configuration (FIG. 2A) wherein the jaw members 430, 432 are substantially spaced from one another, and the knife blade 456 is in a retracted or proximal position with respect to the jaw members 430, 432. The initial distal position of the trigger 422 is actively maintained by the influence of the spring 419 on the knife collar 410. The distal position of the moveable handle 422, however, is only passively maintained, e.g., by internal friction within the jaw actuation mechanism. When both the moveable handle 422 and the knife ' -25CA 02813637 2013-04-23 trigger 426 are in the distal, un-actuated position, pivotal motion of the knife trigger 426 in a proximal direction, i.e., toward the stationary handle 420, is prohibited by interference between the trigger 426 and moveable handle 422. This interference prohibits advancement of the knife blade through the knife channel 458 when the end effector 414 is in the open configuration.

[0088] The movable handle 422 may be moved from the distal position of FIG. 15A to the intermediate position depicted in FIG. 15B to move the jaw members 430, 432 to the closed configuration (FIG. 2B). As the movable handle 422 pivots about the pivot boss 479 in the direction of arrow Ml (FIG. 15B), the drive surface 497b of the movable handle 422 engages the proximal rim 484b of the drive collar 484. The drive collar 484 and the spring 489 are both driven proximally against the proximal lock collar 415 and, thus, the inner shaft member 480 is driven proximally in the direction of arrow M2 (FIG. 15B). As discussed above with reference to FIG. 6, proximal movement of the inner shaft member 480 serves to draw the cam pin 492 proximally though the cam slots 430c, 432c of the jaw members 430, 432, respectively, and thus pivot the jaw members 430, 432 toward one another. As the jaw members 430, 432 engage one another and no further pivotal movement of the jaw members 430,432 may be achieved, the jaw actuation mechanism “bottoms out” and further proximal movement of the cam pin 492 and the inner shaft member 480 is prevented.

[0089] The movable handle 422 may be moved from the intermediate position of FIG. 15B to the actuated or proximal position of FIG 15C to increase the pressure applied by the jaw members 430, 432. As the movable handle 422 pivots further about the pivot boss 479 in the direction of arrow M3 (FIG. 15C), the drive surface 497b presses the proximal rim 484b of the drive collar 484 further distally against the spring 489 in the direction of arrow M4 (FIG. 15C). The spring 489 is compressed against the proximal lock collar 415, and a tensile force is

-26CA 02813637 2013-04-23 transmitted through the inner shaft member 480 to the jaw members 430, 432. The tensile force supplied by the spring 489 ensures that the jaw members 430, 432 apply an appropriate pressure to effect a tissue seal. When the movable handle 422 is in the actuated or proximal position, electrosurgical energy may be selectively supplied to the end effector 414 to generate a tissue seal.

[0090] When the movable handle 422 is in the actuated or proximal position, a t-shaped latch 422a extending proximally from an upper portion of the moveable handle 422 is received in a railway 420a supported within the stationary handle 420. The railway 420a serves to temporarily lock the movable handle 422 in the proximal position against the bias of the spring 489. Thus, the railway 420a permits the maintenance of pressure at the end effector 414 without actively maintaining pressure on the movable handle 422. The flange 422a may be released from the railway 420a by pivoting the movable handle 422 proximally and releasing the movable handle 422 to move under the influence of the spring 489. Operation of the railway 420a is described in greater detail in U.S. Patent Application Serial No. 11/595,194 to Hixson et al., now U.S. Patent No. 7,766,910. In some embodiments (not shown), the latch 422a and the railway 420a may be eliminated to provide an instrument without the temporary locking capability provided by these features.

[0091] When the movable handle 422 is in the actuated or proximal position, the knife trigger 426 may be selectively moved from the distal position of FIG. 15C to the proximal position of FIG 15D to advance the knife blade 456 distally through knife channel 458. The knife trigger 426 may be pivoted in the direction of arrow M5 (FIG. 15D), about pivot boss 403 to advance the flange 426b of the knife trigger 426 distally in the direction of arrow M6 such that the pin boss 439b translates within slot 427b from the position shown in FIGS. 15A - 15C to the

-27CA 02813637 2013-04-23 position shown in FIG. 15D. Although not explicitly shown in FIGS. 15A - 15D, pin boss 439a translates within slot 427a in the same maimer as described above with respect to pin boss 439b and slot 427b. Movement of flanges 426a, 426b draws the knife collar 410 distally, which induces distal longitudinal motion of the knife 402 by virtue of the coupling of knife 402 to the knife collar 410 via the dowel pin 493 extending through the through bore 408a, as described above with reference to FIGS. 3 A and 14B.

[0092] While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as examples of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

[0093] Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.

-28The embodiments of the present invention for which an exclusive property or privilege is claimed are defined as follows: