Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
  • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
  • A61B18/14—Probes or electrodes therefor
  • A61B18/1442—Probes having pivoting end effectors, e.g. forceps
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
  • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
  • A61B18/14—Probes or electrodes therefor
  • A61B18/1402—Probes for open surgery

Definitions

• Electrosurgery involves the application of electrical energy to tissues. Water is evaporated from tissues during electrosurgery, and with proper control of the intensity, frequency and duration of the applied energy, a surgeon can either coagulate or cut tissues.
• a number of expired patents disclose electrocautery forceps having a pair of U-shaped jaws and a cutting wire which i ⁇ advanced between the arms of the jaws to cut tissue clamped between them.
• a purely mechanical shielded cutting blade is employed, in conjunction with bipolar coagu ⁇ lating jaws. Both the blade and the jaws are independently movable along the axis of the tool; each is retracted by a spring, so that the jaws are normally closed.
• An object of the invention is to provide a small-diameter tool which can grasp and coagulate tissues, and then cut them while the grasp is maintained.
• Another object of the invention is to enable a surgeon to move coagulating jaws and an associated cutting blade indepen ⁇ dently, without having to worry about interference between the blade and the jaws.
• a further object is to enable a surgeon to rotate the jaws about the axis of the tool.
• a reduced- diameter grasping, coagulating and cutting forceps including a handgrip-shaped housing with a protruding barrel, a pair of electrocautery jaws which are closed by interference with the mouth of the barrel when the jaws are retracted, and an independently movable blade disposed between the jaws.
• the jaws are opened by squeezing a trigger to advance them, and the blade is advanced by pressing a lever with the thumb.
• Figure 1 is a view of a grasping, cutting and coagulating forceps, partially sectioned on a vertical plane substantially bisecting the device, showing the handle of the forceps and a rear portion of a barrel;
• Figure 2 is an oblique view of the tool shown in Fig. 1, with a smaller diameter barrel;
• Figure 3 is a sectional view, taken from the side, of the front portion of the barrel and jaws protruding therefrom, with the cutting blade in its advanced position;
• Figure 4 is a top sectional view thereof, but with the blade retracted
• Figure 5 is a perspective view of the distal end of the forceps;
• Figure 6 is a sectional view taken on the line 6-6 in Figure 4;
• Figure 7 is a perspective view of a modified molded plastic jaw assembly, with a blade between the jaws;
• Figures 8 and 9 are isometric views of the distal end of the forceps, showing the modified jaws opened and closed, respectively;
• Figure 10 is a detail of a metal electrode
• Figure 11 shows the electrode molded into a jaw subassembly
• Figures 12 and 13 show two such subassemblies being prepared for a final molding step to connect them together;
• Figure 14 shows the final jaw assembly
• Figure 17 is a sectional view of the forceps, looking in the distal direction, showing a thumb wheel and rotary electrical joint;
• Figure 18 is a ⁇ ide view of the elements shown in Figure 17;
• Figure 20 is a sectional view, like Figure 17, of a second embodiment of the invention.
• Figure 21 is a ⁇ ide view of the element ⁇ ⁇ hown in Figure 18.
• proximal means toward the end of the forceps closer to the handle; “distal” connotes the end from which the jaws extend.
• a grasping and cutting forceps embodying the invention includes a molded plastic housing 10 (Fig. 1) having a down ⁇ wardly extending handle 12.
• a pre ⁇ ently preferred material for the hou ⁇ ing i ⁇ produced by Mon ⁇ anto under the trademark Lu ⁇ tran ABS.
• the housing is formed in sub ⁇ tantially ⁇ ymmet- rical halves joined on a vertical plane of symmetry "V".
• a tubular barrel 14 protrudes from the forward end of the housing, where it i ⁇ retained between the halves by the combination of a fitting 16 secured to the rear of the barrel and a corresponding annular groove 18 in the housing.
• the ite ⁇ running coaxially through the barrel 14 are flattened, stiff stainle ⁇ ⁇ teel wire ⁇ which are flattened to form elongate tine ⁇ 21 capable of substantial bending. They are connected at their forward or distal ends (Fig. 4) to respective jaws 22,24, and can move along the axis of the barrel to advance and retract the jaws.
• the rearward (proximal) ends of the tines 21 (Fig. 2) are clamped within a compression fitting 27 which in turn i ⁇ connected by mean ⁇ of a metal tube 20 to a clevi ⁇ 28 confined within vertically extending ⁇ lot ⁇ 30 at the upper end of spaced arms of an actuating lever 32.
• the lever is supported within the housing by a pin 34 (Fig. 1), whose ends are supported by the housing.
• the lever is concealed, except for a trigger portion 36 that extends through a slot 38 at the forward side of the handle.
• the coagulating jaws 22, 24 extend beyond the barrel mouth 70 a variable distance, depending on the trigger pressure and the thickne ⁇ s and nature of any tissues captured between the jaws.
• Maximum jaw ⁇ troke i ⁇ about 0.25 inch (6.25 mm) .
• Each jaw i ⁇ cut from ⁇ tainless steel stock by electric discharge machining, so that it has a "U" shape when viewed vertically, as in Figure 4, and is rather flat when viewed from the side.
• the arms of the jaw ⁇ are ⁇ haped so as to form what appear ⁇ , when viewed from the side in Figure 3 as a bulge comprising proximal diverging segment ⁇ 66 and distal converging segments 68.
• the bulge i ⁇ larger than the barrel diameter, so that the diverging segments act as camming surface ⁇ again ⁇ t the internally beveled mouth 70 of the barrel when the jaw ⁇ are retracted.
• the jaws and their supporting tines are entirely covered (except for the jaws' tips, their serrated mating surfaces, and the tines' proximal ends) with a dielectric thermosetting polymeric re ⁇ in material 72 which prevents electrical contact between the tines and the barrel.
• the material is sprayed on as a liquid, while the tips and serrated surfaces are protec ⁇ ted from the spray by masking. Heat is then applied to set the resin.
• a preferred polymer for the coating is polyurethane having a tensile strength of about 10,000 psi and a dielectric strength of about 5600 volts per mil, applied to achieve a final thickness of 3 - 10 mils.
• the tines are kept separate, within the barrel, by at least one plastic spacer 90 (Fig. 6) having a cylindrical envelope.
• the outside diameter of the spacer is slightly less than the inside diameter of the barrel, to permit the spacer to slide fore and aft as the device is operated, while preventing unacceptable levels of inflation gas leakage past the spacer.
• Two diametrally opposed recesses 92 are formed in the spacer, each extending parallel to the length of the barrel, and each having a cros ⁇ -section like that of the tines.
• the tips 94 at either end of each reces ⁇ are spaced closer than the tine width, so that during assembly, the tines snap into the reces ⁇ es.
• the presently preferred material for the spacer is an ABS sold under the trademark Lustran 248; however, other material ⁇ may prove suitable.
• Flexible conductors 76 are electrically connected to the proximal ends of the jaw wires, by means of the compres ⁇ ion fitting 27 mentioned above.
• the fitting consists of two coaxial components, the inner one of which spaces the tines apart and is insert molded onto a grooved tube which support ⁇ the push rod 26.
• the external component surrounds the internal component and has holes receiving set screws which press the conductors against the respective tines.
• These conductors shown diagrammatically, pass down through the handle and out the bottom to suitable connectors (not shown) which may be plugged into a power supply 78 controlled by a foot switch 80.
• a cutting blade 62 (Figs. 3 - 5) is affixed to the distal end of the push rod 26.
• the blade is oriented perpendicular to the jaws, so that it is positioned in the gaps between the arms of each "U", with the cutting edge of the blade extending vertically.
• the blade is substantially rectangular, having a sharp, square cutting edge at its forward end, and a width providing a close sliding fit within the barrel.
• the rear 5 edge of the blade is rigidly affixed to the forward end of the blade push rod by welding or brazing, for example.
• the rod's diameter is substantially greater than the blade thickness.
• the cutting edge is about even with the front end of the barrel when the blade is in its o normal rest position (retracted). In this position, the blade is shielded by both the barrel and the jaw tips 65 to help prevent accidental cuts.
• the blade's maximum stroke is about 0.60 inch (15 mm) when the jaws are fully extended, but less when the jaws are retracted. s
• both the jaws and the blade can be indepen ⁇ dently reciprocated by the surgeon. But, were the blade to be extended so far as to contact the looped end of the jaws, not only would be the blade edge be dulled, but also the blade would short the electrical path between the jaws. Thus, it is o important to prevent overextension of the blade, and yet to maximize the stroke of the blade when the jaws are not retrac ⁇ ted fully.
• forward blade motion is controlled by a stop whose position is a function of jaw s extension.
• the stop is in the form of a pin 82 protruding from the actuating lever 32, through a slot 84 in the housing 10.
• the flattened rear surface on the pin is engaged by the forward side of the thumb lever just before o the blade contacts the jaw tips, regardless of jaw position. Inasmuch as the pin is above the trigger pivot, it moves in the same direction as (but less rapidly than) the jaws. The further forward the jaws are advanced by squeezing the trigger, the further forward the stop is, allowing the blade 5 to be advanced farther.
• the range of blade move ⁇ ment is reduced substantially when the trigger is released, to protect the blade and prevent unwanted electrical contact.
• tissue is grasped between the jaws by first squeezing the trigger to open the jaws, then advancing the jaws over the tissue and releasing the trigger.
• the tor ⁇ ion spring pulls the jaws back into the mouth of the barrel, whose 5 camming action drives the jaw ⁇ together, clamping the tissue.
• the retracting spring force and jaw geometry are chosen to produce a clamping force in the range of 1 - 3 pounds, which is sufficient, with the jaws described, to produce a maximum pulling force of at least one pound on the o tissues.
• the foot pedal 80 when the surgeon depresses the foot pedal 80, a high frequency voltage is impressed acros ⁇ the jaw ⁇ , to coagulate the ti ⁇ ue ⁇ .
• the foot pedal is relea ⁇ ed, and — while the ti ⁇ sues are ⁇ till held by the jaw ⁇ — the blade i ⁇ advanced, s cutting through the ti ⁇ ue ⁇ , by pre ⁇ ing one of the thumb lever ⁇ forward.
• the tension spring retracts the blade.
• the ti ⁇ ue is released by squeezing the trigger.
• the surgeon also can perform spot coagulation by touching o the uncoated tips of the jaws to tissues.
• Figure 7 show ⁇ a modification in which the jaw ⁇ are formed of a molded pla ⁇ tic, rather than metal.
• the pla ⁇ tic jaws 122, 124 have serrated mating inner surface ⁇ 164, each 5 comprising about ten teeth having a pitch of about .076 inch (1.8 mm).
• the oblique faces of the teeth are at about 45° to the length of the jaws, and the teeth are arranged so that they mesh when the jaws clo ⁇ e about a horizontal plane "H".
• the jaws 5 On their outer surfaces, proximal to the teeth, the jaws 5 have enlargements 166. Even when the jaws are closed, the distance spanned by the enlargements is greater than the barrel diameter, so that the proximal, diverging ramp surfaces 168 of the enlargements act a ⁇ camming surfaces against the internally beveled mouth 170 of the barrel. A camming action drives the jaws together when they are retracted (Fig. 9).
• Metal electrodes 172, 174 each preformed from stainle ⁇ wires having a rectangular cro ⁇ -section into substantially a "U" shape, are molded into the jaws 122, 124.
• Each electrode has a distal portion which pas ⁇ e ⁇ around the teeth at the jaw tip ⁇ 165, with it ⁇ sides exposed to permit the surgeon to coagulate small bleeders without having to grasp them.
• the proximal ends of the electrodes are embedded within the plastic; intermediate portions of the electrode ⁇ , offset inward from the di ⁇ tal portion ⁇ , extend through ⁇ lots formed in the first few jaw teeth.
• the proximal ends of the electrodes are molded within the cylindrical plastic plug 121, which electrically insulates the wires from one another, as well as from the barrel.
• the plug has a close sliding fit within the barrel, so that it func ⁇ tions as a dynamic seal to prevent loss of inflation gas from the surgical site.
• the presently preferred material for the plug and jaw as ⁇ embly i ⁇ Hoech ⁇ t Celane ⁇ e's Vectra LCP (a liquid crystal co-polyester amide); however, other materials may prove suitable, including General Electric's Ultem ( poly- etherimide resin). General Electric's Lexan (a polycarbonate), and Monsanto's Lustran SAN (a ⁇ tyrene-acrylonitrile) .
• each electrode protrude ⁇ from the proximal end of the plug; the two ends are spaced and shaped to fit within a standard female connector installed at the end of the conductors which pas ⁇ through the hou ⁇ ing.
• the jaw assembly i ⁇ described as "integral" in that it cannot be disa ⁇ embled, and it ⁇ part ⁇ are integrated by molding. However, the a ⁇ embly may be produced in several steps, illustrated in Figures 10 - 14.
• Figure 10 shows one metal electrode 172, ready for insertion molding into a sub- assembly (Fig. 11) comprising one jaw, the embedded electrode, and half of the plug. One end of the electrode protrudes from the proximal end of the plug half.
• Figure 12 show ⁇ two sub- assemblies 190 being placed together over the end of the tube 20. Note the flats 192 at the end of the tube, which engage within corresponding 194 flats molded in the subassemblies.
• Figure 13 shows a ring 196 being installed to hold the plug s halves together, and a cap 198 for holding the jaw tips together, as material is molded around the plug halves to form the finished assembly shown in Figure 14.
• Figure 15 illustrates a modified form of the invention, where the blade is wholly enclosed by the jaws, to better io shield the blade and thus prevent accidents.
• a clear plastic such as a ⁇ Lexan for thi ⁇ application.
• the jaw ⁇ can be rotated or turned within the barrel.
• the jaw actuating tube 20 passes through an electrical joint including a rotor 286 in which the tube 20 is secured by adhesives, molding, or an interference fit.
• the rotor has opposed flats 288, visible in Figure 16, which engage corresponding flat ⁇ on the interior ⁇ urface of the zo thumb wheel 290, and prevent relative rotation.
• Thi ⁇ spline connection might take other forms. In any event, there is a sliding fit between the rotor 286 and the thumb wheel 290, so that the rotor can move fore and aft as the jaws are actuated and released, without requiring like movement of the thumb
• the thumb wheel is prevented from moving substantially in the axial direction, because it protrudes laterally through two slot ⁇ 292 in the forcep ⁇ body, one on either ⁇ ide.
• the slots are just wide enough to permit free movement of the thumb wheel. so
• Each electrode is borne against by a bras ⁇ contact or bru ⁇ h 300 having a ⁇ pring bias forcing
• Each bru ⁇ h is heat- staked to the inside surface of the body at 302.
• the brushes are in turn electrically connected to the electric wires 304 which pas ⁇ out through the bottom of the handle to a power supply, as mentioned previously.
• the thumb wheel, slip rings and brushes function together as a rotary joint to permit unlimited jaw rotation.
• the slip rings 296, 298 are concentric members of different diameter, formed with coplanar annular contact surfaces, facing rearward. That is, the exposed contact surface of each ring is in a plane perpendicular to the axis of the tool.
• the slip rings 396, 398 are not coplanar, being offset in the axial direction, and their contact surfaces are cylindrical; that is, the outer circumference of each ring is its contact surface, and the brushes bear inward against the respective rings. Manufacturing considerations have led us to make these rings different diameters, but it is conceivable that they might be identical.
• the periphery of the thumb wheel 290 is irregular, having the general shape of a star whose eight rounded points 306 provide added traction and feel.
• the preferred drag provided by the thumb wheel and electrical contacts i ⁇ about 0.3 inch-pound (3.3 gram-meter).
• detents may be ridges or depre ⁇ ion ⁇ formed right in the ⁇ lip ring ⁇ , if de ⁇ ired.

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Cited By (24)

Citations (6)

• 1996
  • 1996-08-07 AU AU67690/96A patent/AU6769096A/en not_active Abandoned
  • 1996-08-07 WO PCT/US1996/012919 patent/WO1997005829A1/en active Application Filing

Patent Citations (7)

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