Note: Descriptions are shown in the official language in which they were submitted.
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r BIPOLAR ENDOSCOPIC SURGICAL SCISSOR INSTRUMENT
TECHNICAL FIELD
l. 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
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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.
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In order to overcomè the problems associated with
monopolar cautery instruments, bipolar instruments have been
introduced. In bipolar electrosurgical instruments, two
electrodes which are closely spacecl 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 wou]d 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
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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 hemostatically 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
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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.
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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 utiliz,es 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;
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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
. 30 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
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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
- 5 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
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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 2~d 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 superalloy 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
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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 metalblades. As the blades are moved from the open position of
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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
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12
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 the
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 with
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 the
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.
