BIPOLAR ENDOSCOPIC SURGICAL SCISSOR INSTRUMENT

Abstract: Endoscopic bipolar scissor blades (26, 28) are provided and include a pair of metallic electrically conductive blades each having a cutting edge (26a, 28a) and an adjacent shearing surface (26f, 28f), where at least one of the blades is partially covered with an electrically insulating ceramic material (29). The partial ceramic covering covers substantially the entire cutting edge of the blade and a relatively small portion of its shearing surface adjacent to the cutting edge. If desired, a larger angled portion (29b, 28f) of the shearing surface may be covered. The ceramic covering is applied by either masking the portion of the blade which is not to be covered and by spraying the masked blade with a ceramic, or by bonding a thin ceramic member to the blade. In another embodiment of the invention, a scissor blade (126, 128) is provided with an insert receiving channel groove (128g) on a portion of its shearing surface adjacent to its cutting edge. A ceramic insert (129) having a groove engaging tongue portion (129c) is inserted into the channel groove (128g) and forms a ceramic cutting edge on the metallic blade. An endoscopic bipolar cautery scissors instrument (10) which utilizes the partially covered blades of the invention is also described.

Description: BIPOLAR ENDOSCOPIC SURGICAL SCISSOR INSTRUMENT TECHNICAL FIELD 1. Field of the Invention The invention relates to endoscopic surgical instruments. More particularly, the invention relates to endoscopic surgical scissors having scissor blades made out of a combination of conductive and non-conductive materials. The invention has particular use with respect to bipolar endoscopic cautery. For purposes herein, the term "endoscopic instruments" is to be understood in its broadest sense to include laparoscopic, arthroscopic, and neurological instruments, as well as instruments which are inserted through an endoscope. 2. State of the Art Endoscopic surgery is widely practiced throughout the world today and its acceptance is growing rapidly. In general, endoscopic/laparoscopic surgery involves one or more incisions made by trocars where trocar tubes are left in place so that endoscopic surgical tools may be inserted through the tubes. A camera, magnifying lens, or other optical instrument is often inserted through one trocar tube, while a cutter, dissector, or other surgical instrument is inserted through the same or another trocar tube for purposes of manipulating and/or cutting the internal organ. Sometimes it is desirable to have several trocar tubes in place at once in order to receive several surgical instruments. In this manner, organ or tissue may be grasped with one surgical instrument, and simultaneously may be cut with another surgical instrument; all under view of the surgeon via the optical instrument in place in the trocar tube. Various types of endoscopic surgical instruments are known in the art. These instruments generally comprise a slender tube containing a push rod which is axially movable within the tube by means of a handle or trigger-like actuating means. An end effector is provided at the distal end of the tube and is coupled to the push rod by means of a clevis so that axial movement of the push rod is translated to rotational or pivotal movement of the end effector. End effectors may take the form of scissors, grippers, cutting jaws, forceps, and the like. Because of their very small size and the requirements of strength and/or sharpness, end effectors are difficult to manufacture and are typically formed of forged stainless steel. As such, they form an expensive portion of the endoscopic instrument. Modern endoscopic procedures often involve the use of electrocautery, as the control of bleeding by coagulation during surgery is critical both in terms of limiting loss of blood and in permitting a clear viewing of the surgical site. As used herein, cautery, electrocautery, and coagulation are used interchangeably. Several types of electrocautery devices for use in endoscopic surgery are described in the prior art. Monopolar electrosurgical instruments employ the instrument as an electrode, with a large electrode plate beneath and in contact with the patient serving as the second electrode. High frequency voltage spikes are passed through the instrument to the electrode (i.e., end effector) of the endoscopic instrument to cause an arcing between the instrument and the proximate tissue of the patient. The current thereby generated continues through the patient to the large electrode plate beneath the patient. Monopolar cautery has the disadvantage that the current flows completely through the patient. Because control of the current path through the body is not possible, damage can occur to tissue both near and at some distance from the surgical site. In addition, it is has been observed that monopolar cautery can result in excessive tissue damage due to the arcing between the end effector and the tissue. In order to overcome the problems associated with monopolar cautery instruments, bipolar instruments have been introduced. In bipolar electrosurgical instruments, two electrodes which are closely spaced together are utilized to contact the tissue. Typically, one end effector acts as the first electrode, and the other end effector acts as the second electrode, with the end effectors being electrically isolated from each other and each having a separate current path back through to the handle of the instrument. Thus, in a bipolar instrument, the current flow is from one end effector electrode, through the tissue to be cauterized, to the other end effector electrode. U.S. Patent #3,651,811 to Hildebrandt describes a bipolar electrosurgical scissors having opposing cutting blades forming active electrodes. The described scissors enables a surgeon to sequentially coagulate the blood vessels contained in the tissue and then to mechanically sever the tissue with the scissor blades. In particular, with the described bipolar electrosurgical scissors, the surgeon must first grasp the tissue with the scissor blades, energize the electrodes to cause hemostasis, de-energize the electrodes, and then close the scissor blades to sever the tissue mechanically. The scissors are then repositioned for another cut accomplished in the same manner. With the bipolar electrosurgical scissors of Hildebrandt, the surgeon cannot maintain the electrodes in a continuously energized state because the power supply would be shorted out and/or the blades damaged if the blades are permitted to contact each other while energized. The disadvantages of the bipolar scissors of Hildebrandt are overcome by the disclosure in U.S. Patent Nos. 5,324,289 and 5,330,471 to Eggers. In its preferred embodiment, the bipolar electrosurgical scissors of Eggers comprise a pair of metal scissor blades which are provided with an electrically insulating material interposed between the shearing surfaces of the blades so that when the scissor blades are closed, the metal of one blade never touches the metal of the other blade; i.e., the insulating material provides the cutting edge and the shearing surface. With the arrangement provided by Eggers, a cautery current will pass from the top back edge of the bottom metal blade through the tissue which is to be cut and to the bottom back edge of the top metal blade directly in advance of the cutting action. As the scissors are gradually closed, the hemostasis preferentially occurs at a location just in advance of the cutting point which itself moves distally along the insulated cutting edges of the blades in order to sever the he ostatically heated tissue. With this arrangement, the scissors may be maintained in a continuously energized state while performing the cutting. The Eggers patent describes various alternative embodiments of the bipolar scissors, including the use of metal blades with only one blade being insulated on its shearing surface, and the use of insulating blades with back surfaces coated with metal. Eggers teaches insulating the entire cutting edge and shearing surface of at least one blade. DISCLOSURE OF INVENTION It is therefore an object of the invention to provide an endoscopic bipolar scissors in which may be maintained in an energized state continuously throughout a cutting procedure. It is also an object of the invention to provide an endoscopic scissor blade for use in an endoscopic bipolar scissors which includes an insulating portion which constitutes only a portion of the shearing surface of the blade. It is another object of the invention to provide an endoscopic scissor blade having an insulating portion and which is inexpensive to manufacture. In accord with these objects which will be discussed in detail below, the endoscopic bipolar scissor blades of the present invention include a pair of metallic electrically conductive blades each having a cutting edge and an adjacent shearing surface. At least one of the blades is partially covered with an electrically insulating ceramic material which is preferably located along substantially the entire cutting edge of the blade and a relatively small portion of its shearing surface adjacent to the cutting edge. In an alternate embodiment of the invention, the ceramic covering constitutes a relatively larger portion of the shearing surface of the blade, but still not the entire shearing surface. The ceramic covering is preferably applied by masking the portion of the blade which is not to be covered and by spraying the masked blade with a ceramic vapor. The ceramic covering may also be formed by bonding a relatively thin piece of ceramic material to the shearing surface of the blade. Alternatively, at least one of the blades is provided with an insert receiving channel groove on a portion of its shearing surface adjacent to its cutting edge. A ceramic insert having a groove engaging tongue portion which is inserted into the channel groove of the scissor blade is used to form a ceramic cutting edge on the metallic blade. The scissor blades of the invention may be either curved or straight. Because the scissor blades are intended for use as part of an endoscopic instrument, each blade is preferably provided with a first hole which receives an axle or clevis pin around which the blades rotate. In addition, each blade is preferably provided with a pin or protrusion extending from a proximal or base portion of the blade. The pins are provided to receive links which couple the blades to an actuator mechanism. In use, as the scissor blades are moved relative to each other from the open to the closed position, the portions of their respective shearing surfaces which lie proximal of the distally moving point of engagement of the respective cutting edges are bowed apart from each other. The endoscopic bipolar cautery scissors instrument which utilizes the blades of the invention is substantially as is described in copending application U.S. Serial No. 08/284,793, the complete disclosure of which is hereby incorporated by reference herein, and utilizes a push rod assembly with two conductive push rods which are stabilized and insulated relative to each other. The distal ends of the push rods are coupled to the scissor blades by links. The proximal ends of the push rods extend through a handle and lever of the scissors instrument and present electrical cautery pins onto which a standard bipolar cautery plug can be mated. Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a broken, partially transparent, partially sectional, side elevation view of an endoscopic bipolar scissors according to the invention; Figure 2 is an enlarged side elevation view of a first non-insulated scissor blade according to the invention; Figure 2a is a top view of the scissor blade of Figure 2; Figure 2b is an enlarged sectional view taken along line 2b-2b in Figure 2; Figure 3 is an enlarged side elevation view of a second insulated scissor blade according to the invention; Figure 3a is a top view of the scissor blade of Figure 3; Figure 3b is an enlarged sectional view taken along line 3b-3b in Figure 3 illustrating a first embodiment of the scissor blade of Figure 3; Figure 3c is a view similar to Figure 3b illustrating a second embodiment of the scissor blade of Figure 3; Figure 3d is a view similar to Figure 3 illustrating a third embodiment of the scissor blade of Figure 3; Figure 3e is an enlarged sectional view taken along line 3e-3e in Figure 4; Figure 4 is an enlarged transparent side view elevation view of the scissor blades of Figures 2 and 3 in an open position representing an early stage of a cutting operation; Figure 4a is an enlarged sectional view taken along line 4a-4a in Figure 4; Figure 5 is an enlarged transparent side elevation view of the scissor blades of Figures 2 and 3 in a closed position representing the final stage of a cutting operation; and Figure 6 is an enlarged top view of the scissor blades of Figures 2 and 3 in a closed position representing the final stage of a cutting operation. MODE FOR CARRYING OUT THE INVENTION Referring now to Figure 1, an endoscopic bipolar scissors instrument 10 includes a proximal handle 12 with a manual lever actuator 14 pivotally coupled to the handle by a pivot pin 15. A hollow tube 16 is rotatably coupled to the handle 12 and is preferably rotatable about its longitudinal axis relative to the handle 12 through the use of a ferrule 18 such as described in detail in previously incorporated copending application Serial Number 08/284,793. A push rod assembly 20 extends through the hollow tube 16 and is coupled at its proximal end 22 to the manual lever actuator 14 as described in more detail in copending application Serial Number 08/284,793. The distal end of the tube 16 has an integral clevis 24 within which a pair of scissor blades 26, 28 are mounted on an axle screw 30. The distal end 23 of the push rod assembly 20 is coupled to the scissor blades 26, 28 so that reciprocal movement of the push rod assembly 20 relative to the tube 16 opens and closes the scissor blades 26, 28. It will be appreciated that the reciprocal movement of the push rod assembly 20 relative to the tube 16 is effected by movement of the manual lever actuator 14 relative to the handle 12. The clevis 24 and the axle screw 30 are both provided with insulation as described in copending application Serial Number 08/284,793 so that the scissor blades 26, 28 are electrically insulated from each other at their coupling to the clevis. The presently preferred embodiment of the push rod assembly 20 includes a pair of stainless steel rods 32, 34 which are molded into a proximal collar 36 and captured in a distal collar 46. The proximal collar has a radial groove 40 in its distal portion and an increased diameter proximal portion 37 which carries a pair of electrical coupling pins 39, 41 which are electrically coupled to the rods 32, 34 respectively. As shown, the pins 39, 41 are spaced farther apart from each other than the rods 32, 34 so as to accommodate a standard cautery connector. The rods 32, 34 are covered with insulating high density polyethylene (HDPE) tubes along substantially their entire length between the proximal and distal collars 36, 46. A plurality of spaced apart polypropylene cylinders 50 are molded about the rods between the proximal collar 36 and the distal collar 46. These cylinders stabilize the rods against helical twisting when the tube 16 is rotated. By being discontinuous, the cylinders 50 prevent the push rod assembly from warping. Turning now to Figures 2, 2a, and 2b, a first, non- insulated, electrically conductive scissor blade 26 according to the invention is shown with a curved distal portion 26a, a lower proximal tang 26b, and a mounting hole 26c therebetween. A connecting lug 26d extends orthogonally outward from the surface of the tang 26b in a first direction. The distal portion 26a includes an lower cutting edge 26e and an inner surface 26f (also called the shearing surface). As seen in Figures 3, 3a, and 3b, a second, partially insulated, electrically conductive scissor blade 28 according to the invention is configured similarly to the first scissor blade and has a curved distal portion 28a, an upper proximal tang 28b, and a mounting hole 28c therebetween. A connecting lug 28d extends orthogonally from the surface of the tang 28b in a second direction which is opposite to the first direction mentioned above. The distal portion 28a- includes an upper edge 28e and an inner surface or face 28f. The scissor blades 26, 28 may be made from a cobalt superaHoy such as cobalt chrome, or from stainless steel. According to a first embodiment of the invention, the upper edge 28e and a portion of the inner surface 28f of the blade 28 is covered with an electrically non-conductive ceramic 29. The ceramic covering defines the cutting edge 29a which is spaced apart from the upper edge 28e of the blade 28 and also defines a portion 29b of the shearing or inner surface 28f of the blade 28. The ceramic covering 29 may be applied by any known means. It is presently preferred, however, that a lower portion of the inner surface 28f of the blade 28 be masked and that the ceramic 29 be sprayed onto the upper portion of the inner surface 28f and the upper edge 28e of the blade 28. Alternatively, the ceramic covering 29 may be provided as a relatively thin ceramic member which is bonded to the blade. It should be appreciated that while the surface 29b of the ceramic 29 is shown to lie in a different plane than the remainder of the shearing or inner surface 28f, the upper portion of the blade could be machined or otherwise formed so that upon application of the ceramic portion 29, the surfaces 29b and 28f lie in substantially the same plane. According to a second embodiment of the invention, which is shown in Figure 3c, a scissor blade 128 is provided which is substantially the same as scissor blade 28 except for a tongue receiving groove 128g which extends along the inner surface 128f of the blade. An electrically non- conductive ceramic insert 129 is provided with a groove engaging tongue 129c and is inserted into the groove 128g of the blade 128. The insert 129 defines the cutting edge 129a of the blade 128 and also defines an upper portion 129b of the shearing surface 128f of the blade 128. The tongue receiving groove 128g may be provided by machining the blade 128 or may be molded into the blade 128 during casting of the blade. The ceramic insert 129 is cast or molded with an integral groove engaging tongue 129c which is kept in place in the groove 128g by an adhesive (not shown) , a friction fit, or any other desired mechanism. Again, it will be appreciated that the upper portion of the blade could be machined or otherwise formed so that upon application of the ceramic portion 129, the surfaces 129b and 128f lie in substantially the same plane. According to a third embodiment of the invention, which is shown in Figures 3d and 3e, a scissor blade 228 is provided which is substantially the same as the blade 28 and is partially coated with an electrically non-conductive ceramic 229. The only significant difference between this embodiment and the first embodiment is that in the first embodiment, only a relatively small portion of the inner surface of the blade was coated with ceramic insulator, while in this embodiment a relatively larger portion of the inner surface 228f (although not the entire face) of the blade is coated. The ceramic coating 229 is applied to define the cutting edge 229a of the blade 228 and to define part 229b of the shearing surface 228f of the blade. Each of the embodiments of the invention operates in substantially the same manner which is illustrated in Figures 4-6. In Figure 4, the scissor blades 26, 28 are shown in a first open position representing the start of a cutting procedure. It will be appreciated that the only point of contact P between the blades 26 and 28 is where their respective cutting edges 26e, 29a meet. However, because edge 29a is ceramic and substantially non- conductive, no short circuit can develop between the metal blades. As the blades are moved from the open position of Fig. 4 to the closed position of Figures 5 and 6, the point P moves distally along the cutting edges. Because the blades are resilient enough to flex, the blades 26, 28 will flex at all points proximal of point P and remain spaced apart from each other at all points proximal of point P (as seen in Fig. 6) . Thus, it is appreciated that the ceramic coating 29 (or ceramic insert 129, or coating 229) constitutes the cutting edge of one blade and prevents the non-insulated portion of the shearing surface 28f from contacting the shearing surface 26f of the other blade. As mentioned above, the proximal portions 26b, 26d and 28b, 28d of the blades are insulated from each other by insulation in the clevis 30 (Figure 1) . Thus, when the blades are energized with a bipolar current, the current path between the blades is from the shearing surface 26f of the non- insulated blade 26 to the upper edge 28e of the insulated blade 28 behind the ceramic insulator 29b. As these respective portions of the blades are never in contact, the preferential current path is only completed when tissue is interposed between the blades. Therefore, the preferential current path between the blades moves distally with the point of contact P to cauterize tissue just before it is cut by the blades. The only difference between the operation of the embodiments relates to what happens to tissue which remains interposed between the shearing surfaces 26f, 28f proximal of the shearing point P. In the embodiments of Figs. 3b and 3c, such interposed tissue will also be cauterized, while in the embodiment of Fig. 3d, the interposed tissue is less likely to be cauterized due to the arrangement of the insulating surface 229. However, at all times, and in all embodiments, the ceramic coating or insert prevents the blades from short circuiting the cautery current. There have been described and illustrated herein several embodiments of a bipolar endoscopic surgical scissor blade having a partial ceramic surface and an instrument incorporating such blades. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that th invention be as broad in scope as the art will allow and that the specification be read likewise. Thus, while particular electrically insulating and electrically conductive materials have been disclosed, it will be appreciated that other materials could be utilized. Also, while a particular endoscopic instrument incorporating the blades has been shown, it will be recognized that other types of types of endoscopic instruments could be used with the partially coated blades to obtain similar results. Moreover, while particular configurations have been disclosed in reference to the location and size of the insulating coating or insert, it will be appreciated that other configurations could be used as well so long as the insulative material effectively interposes the inner surfaces of the blades during a cutting procedure. Furthermore, while the scissor blades according to the invention have been disclosed as having one partially insulated blade and one non-insulated blade, it will be understood that two partially insulated blades can achieve the same or similar function as disclosed herein. Likewise, it will be appreciated that, if desired, the ceramic coating, bonded member, or insert can be further coated wit a metal coating or layer as discussed in copending U.S. Serial No. 08/354,992, to provide a metal on metal cutting action, provided the added metal coating is insulated by th ceramic from the other metal portion of the blade. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as so claimed.

Claims: BIPOLAR ENDOSCOPIC SURGICAL SCISSOR INSTRUMENT CLAIMS 1. A bipolar electrosurgical instrument (10) for cutting and coagulating tissue comprising: a) first and second electrically conductive blade members (26,28) each blade defining a shearing surface (26f, 28f) and a cutting edge (26a, 28a); b) means for pivotally joining (30, 26c, 28c) said first and second blade members together with their respective shearing surfaces facing one another; c) means (20) coupled to at least one of said first and second blade members for imparting a scissors-like movement relative to the other of said first and second blade members; and d) means (39, 41) for applying a voltage between the metal blade supports of said first and second blade members, wherein at least one of said first and second electrically conductive blade members (26, 28) is provided with an electrically non-conductive portion (29e, 29, 129c, 229e) which extends along substantially all of its cutting edge (29, 129, 229) and an adjacent portion of its shearing surface, but not all of its shearing surface. 2. A bipolar electrosurgical instrument (10) according to claim 1, wherein: said shearing surfaces of said first and second electrically conductive blade members (26, 28) and said blade members are curved. 3. A bipolar electrosurgical instrument (10) according to claim 1, wherein: said electrically non-conductive portion is a ceramic coating (29) . 4. A bipolar electrosurgical instrument according to claim 1, wherein: said electrically non-conductive portion is a ceramic member (29) which is bonded to said at least one of said first and second electrically conductive blade members (26, 28) . 5. A bipolar electrosurgical instrument (10) according to claim 1, wherein: said insulating portion is a ceramic insert (129) . 6. A bipolar electrosurgical instrument (10) according to claim 5, wherein: said ceramic insert (129) has a groove engaging tongue (129c) and said at least one of said first and second electrically conductive blade members has a tongue engaging groove (128g) which engages and is engaged by said groove engaging tongue. 7. A bipolar electrosurgical instrument (10) according to claim 1, wherein: said electrically conductive blade members (26, 28) are formed from a cobalt superalloy or from stainless steel. 8. An endoscopic scissor blade (26, 28) for use in a bipolar endoscopic instrument (10) , said blade comprising: an electrically conductive blade member (26, 28) defining a cutting edge (26e, 28e) and a shearing surface (26f, 28f) ; a layer of electrically non-conductive material (29) affixed to said electrically conductive blade member along substantially all of said cutting edge and a portion of said shearing surface, but not all of said shearing surface. 9. An endoscopic scissor blade (26, 28) according to claim 8, wherein: said electrically conductive blade member includes means (39, 41) for coupling said electrically conductive blade member to a source of voltage. 10. An endoscopic scissor blade (26, 28) according to claim 9, wherein: said electrically conductive blade member includes means (30, 26c, 28c) for pivotally mounting said electrically conductive blade member and means for coupling said electrically conductive blade member to a means for imparting a pivotal movement to said electrically conductive blade member. 11. An endoscopic scissor blade (26, 28) according to claim 9, wherein: said shearing surface is curved. 12. An endoscopic scissor blade (26, 28) according to claim 11, wherein: said layer of electrically non-conductive material is a ceramic coating. 13. An endoscopic scissor blade (26, 28) according to claim 11, wherein: said layer of electrically non-conductive material is a ceramic member (29) which is bonded to said scissor blade. 14. An endoscopic scissor blade (26, 28) according to claim 9, wherein: said layer of electrically non-conductive material is a ceramic insert (129) . 15. An endoscopic scissor blade (26, 28) according to claim 14, wherein: said ceramic insert (129) has a groove engaging tongue (129c) and said electrically conductive blade member has a tongue engaging groove (128g) which engages and is engaged by said groove engaging tongue. 16. An endoscopic scissor blade (26, 28) according to claim 10, wherein: said electrically conductive blade member (26, 28) is formed from a cobalt superalloy or stainless steel.

Inventors: SLATER CHARLES R, SLATER, CHARLES, R.
Applicants: SLATER CHARLES R, SYMBIOSIS CORP, SLATER, CHARLES, R., SYMBIOSIS CORPORATION
Application year: 1996
Main classification: A61B17
IPC codes: A61B18