Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BIPOLAR ENDOSCOPIC SURGICAL SCISSOR BLADES AND INSTRUMENT
INCORPORATING THE SAME
BACKGROUND OF THE INVENTION
.
1. Field of the Invention
The present invention relates generally to endoscopic
surgical instruments. More particularly, the invention relates
to an endoscopic surgical instrument having end effectors 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 and to
include laparoscopic, arthroscopic, and neurological instruments,
as well as instruments which are inserted through an endoscope,
although it is not limited thereto.
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. One type of instrument generally comprises 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
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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, or are cast from
bronze or from a superalloy.
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 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
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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.
Various endoscopic instruments with cautery capability are
known in the art. Several hemostatic bipolar electrosurgical
scissors have also been described. 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.$. 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
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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.
The disadvantage of scissor blades which have non-conductive
cutting edges and shearing surfaces is that they are difficult to
operate. The non-conductive surfaces are relatively non-
lubricous and do not have the smooth operation and feel of a
metal on metal cutting/shearing action. Parent application
Serial Number 08/429,596 discloses scissor blades comprised of an
electrically conductive electrode, an electrically insulating
material, and a coating of titanium dioxide, chromium dioxide, or
zirconium dioxide, where the coating provides a lubricious
surface which simulates a metal on metal feel. In one
embodiment, the electrode layer is a metal blade which is
typically constructed from stainless steel, while the insulating
layer is an alumina ceramic which is deposited, bonded, or
otherwise fixed on the metal blade, and a titanium dioxide
coating is deposited, bonded, or otherwise fixed onto the ceramic
and provides the cutting edge and shearing surface. In another
embodiment, the electrode layer of the scissor blades is a metal
blade, and the titanium dioxide is mixed with the alumina ceramic
and then applied directly to the conductive electrode. In this
preferred embodiment, the ratio by weight of alumina ceramic to
titanium dioxide is 87/13, although the ratio can range from
75/25 to 95/5 and still provide the desired insulation and
lubricity. In a third embodiment of the invention, the
insulating layer is a ceramic support, with the electrode layer
and the titanium dioxide shearing surface layer being deposited,
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bonded, or otherwise fixed to opposite sides of the ceramic
support. In all embodiments, since the coated cutting edges and
preferably at least a portion of the shearing surfaces are
insulated from the electrodes, no short circuit can form between
the electrodes even though the cutting edge and shearing surface
of each scissor blade are in contact with the cutting edge and
shearing surface of the other scissor blade.
In the prior art, as well as in the parent application
hereto, a cross sectional profile of an endoscopic scissor blade
generally defines an included angle of between 60-90~ at the
cutting edge. This may be seen in the prior art Figures of 1 and
la where the blades 26, 28 have an included angle n of
approximately 70~ at their cutting edges 26b, 28b. It is
generally believed in the art that the cutting edge of a surgical
scissor blade, and in particular an endosurgical scissor blade,
must be defined by an angle of no more than 90~ in order to
achieve effective cutting.
U.S. Patent Number 4,709,480 to Takigawa et al. disclosed a
scissors for use in horticulture and for industrial purposes.
Prior art Figure lb shows a cross section of the scissors which
has one metallic cutting blade 11 and one ceramic cutting blade
12. Takigawa et al. teaches that if the cutting edge of a
ceramic cutting blade is defined by an acute included angle, the
ceramic is likely to be damaged. The inventors herein have
confirmed that this is also true in the case of endoscopic
scissors. According to Takigawa et al., the damage to the
ceramic blade is most likely to be caused by the blades
interfering with each other as the bow in the scissor blade
causes their respective cutting edges to press against each other
at a single moving point of contact as the blades are closed.
The solution proposed by Takigawa et al. is to locate the cutting
edge of the ceramic blade away from the shearing surface so that
it never touches the cutting edge of the metallic blade. Thus,
the cutting edge of the ceramic blade disclosed by Takigawa et
al., as shown in prior art Figure lb, is defined by an adjacent
side 16 which forms an obtuse angle n 2 with the shearing surface
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15 and a beveled side 17. While Takigawa et al. does not
specifically disclose what angle is formed by the adjacent side
16 and the beveled side 17 (i.e. the included angle of the
cutting edge), it appears to be close to 90~. The scissors
proposed by Takigawa et al. may have utility in horticulture and
in some industrial applications. However, they are unsuitable
for surgical procedures. As those skilled in the art will
appreciate from prior art Figure lb, when the scissors are used
to cut article "c", the cutting edge of the metallic blade 11
will attempt to sever the article along a virtual plane A-B.
Since the cutting edge of the ceramic blade 12 is not located in
the plane A-B, it will pull the article c up and away from the
plane A-B. Thus, depending on the nature of the article c, it
may be torn apart rather than cut. Scissors of this design would
certainly tear, rather than sever, human tissue.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an
endoscopic scissor blade which includes a ceramic coating which
is resistant to chipping.
It is another object of the invention to provide a pair of
scissor blades for a bipolar cauterizing surgical scissors which
have shearing surfaces that are insulated from cautery surfaces.
It is also an object of the invention to provide a pair of
scissor blades for a bipolar cauterizing surgical scissors which
provide the smooth operation and feel of a metal on metal
cutting/shearing action, and which cut well.
In accord with the objects of the invention, a pair of
bipolar endoscopic scissor blades is provided in which at least
one scissor blade is coated with an electrically non-conductive
ceramic from its cutting edge along at least a contiguous portion
of its shearing surface, with the cutting edge of the coated
blade defining an obtuse angle. The obtuse angle of the cutting
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edge is preferably more than 95~ and less than 140~, and more
preferably between approximately 110~ and 120~.
The blades according to the invention may be configured in
several different ways with regard to the number of layers and
types of material used, the extent of the ceramic coating, and
whether one or both blades are configured in an identical manner.
In a first embodiment, a scissor blade having a partial ceramic
coating is used in conjunction with an uncoated metallic scissor
blade having an acute angle cutting edge. In a second embodiment
of the invention, two substantially identically configured
ceramic coated blades are shown, both having obtuse angle cutting
edges. Other embodiments of the invention include blades having
fully coated shearing surfaces and blades which are laminates of
several different materials. It has been discovered by the
inventors herein that the blades according to the invention
having cutting edges defined by obtuse angles cut well and
provide a good cutting feel to the practitioner. As the angle of
the cutting edge is increased above 90~, the integrity of the
ceramic at the cutting edge is enhanced. Clearly, if the angle
is too large, no cutting will be effected. It has been
discovered by the inventors herein that an angle approximately
95-140~ works well and that a presently preferred angle is
between approximately 110~ and 120~.
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 THE DRAWINGS
r
Figure 1 is an enlarged cross sectional view of prior art
endoscopic scissor blades;
Figure la is a further enlarged portion of Figure 1 showing
the point of contact and the included angles of the cutting edges
of the prior art scissor blades;
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Figure lb is a view similar to Figure 1 of prior art=
horticultural scissor blades;
Figure 2 is a broken side elevation view in partial section
of an endoscopic bipolar scissors instrument;
Figure 3 is an enlarged side elevation view of a pair of
scissor blades incorporating a ceramic coating on one of the
blades;
Figure 4 is an enlarged cross sectional view taken at 4-4 of
Fig. 3 and showing a first embodiment of the invention;
Figure 4a is a view similar to Figure la and showing the
included angles of the blades of the first embodiment of the
invention;
Figure 5 is a view similar to Figure 4 of a second
embodiment of the invention;
Figure 5a is a view similar to Figure 4a of the second
embodiment of the invention;
Figure 6 is a view similar to Figure 5 of a third embodiment
of the invention;
Figure 7 is a view similar to Figure 6 of a fourth
embodiment of the invention;
Figures 8a through 8c are enlarged sectional views
illustrating a presently preferred method of making the scissor
blades of the invention; and
Figure 9 is a view similar to Figure 6 illustrating a
presently preferred embodiment of the invention.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 2 shows the endoscopic bipolar cautery scissors
instrument 10, utilized in the parent application and the related
applications incorporated by reference herein above in which the
end effectors of the present invention find use. The 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 stainless steel 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, 128 are mounted on an axle
screw 30. The distal end 23 of the push rod assembly 20 is
coupled to the scissor blades 26, 128 so that reciprocal movement
of the push rod assembly 20 relative to the tube 16 opens and
closes the scissor blades 26, 128. 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 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 which are
electrically coupled to the rods 32, 34. As shown, the pins 39
are spaced farther apart from each other than the rods 32, 34 so
as to accommodate a standard cautery connector. While the
proximal collar shown has a male connector, a female connector
may be used instead. The rods 32, 34 are covered with an
insulating double lumen polypropylene tube 50 along substantially
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their entire length between the proximal and distal collars 36,
46. The double lumen tube 50 may be discontinuous at a point
inside the tube 16 to provide a rubber air flow seal (not shown)
on the rods 32, 34. According to a presently preferred
embodiment, the distal collar 46 is made from a single ceramic
piece. The electrically conductive rods 32, 34 exit the distal
collar 46 through opposite sides at substantially right angles.
The distal ends of the rods 32, 34 are mechanically and
electrically coupled to the respective blades 26, 128 by
respective electrically conductive links 99.
As shown in Figure 3 the first scissor blade 26 has a distal
portion 26a, a lower proximal tang 26c, and a mounting hole 26d
therebetween. A connecting lug 26e extends orthogonally outward
from the surface of the tang 26c in a first direction. The
distal portion 26a includes a lower cutting edge 26b and an inner
surface 26f (also called the shearing surface). The opposed
second scissor blade 128 is configured similarly to the first
scissor blade and has a distal portion 128a, an upper proximal
tang 128c, and a mounting hole 128d therebetween. A connecting
lug (not shown) extends orthogonally from the surface of the tang
128c in a second direction which is opposite to the first
direction mentioned above. The distal portion 128a includes an
upper cutting edge 128b (defining an obtuse angle as discussed
below) and an inner surface 128f. According to the parent
application and the present invention, at least one of the
scissor blades 26, 128 (in this case blade 128) is coated with an
electrically non-conductive ceramic 128g from its cutting edge
128b along at least a contiguous portion of its shearing surface
128f.
Turning now to Figures 4 and 4a, details of the cutting
edges of a first embodiment of bipolar scissor blades according
to the invention are seen. The conventional metal blade 26 has a
shearing surface 26f and a cutting edge 26b which is defined by
an included angle n of approximately 60~-90~. The scissor blade
128 has a shearing surface 128f which is partially coated with a
ceramic material 128g adjacent to its cutting edge 128b. The
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11
cutting edge 128b of the blade 128 is defined by an obtuse angle
~ which is preferably more than 95~ and less than 140~, and more
preferably between approximately 110~ and 120~. When used in a
bipolar endosurgical instrument such as the one shown in Figure
1, the blades 26, 128 provide the smooth operation and feel of a
metal on metal cutting/shearing action. The ceramic coating 128g
on the blade 128 insures that the shearing surfaces 26f, 128f of
the blades are electrically insulated from each other so that
cautery current my be constantly supplied throughout a cutting
procedure. The included obtuse angle of the cutting edge 128b of
the blade 128 prevents the ceramic coating 128f from chipping at
the cutting edge 128b. Despite the fact that the cutting edge of
the coated blade 128 is defined by an obtuse angle, the scissors
cut very well.
According to a second embodiment of the invention shown in
Figures 5 and 5a, a pair of bipolar scissor blades according to
the invention includes two partially ceramic coated metal blades
126 and 128. In this embodiment, the blade 126 is configured
substantially the same as the blade 128 described above. When
used in a bipolar endosurgical instrument such as the one shown
in Figure 1, the blades 126, 128 provide the smooth operation and
feel of a metal on metal cutting/shearing action. The ceramic
coatings 126g, 128g on the blades 126, 128 insure that the
shearing surfaces 126f, 128f of the blades are electrically
insulated from each other so that cautery current my be
constantly supplied throughout a cutting procedure. The included
obtuse angles of the cutting edges 126b, 128b of the blades 126,
128 prevents the ceramic coatings 126f, 128f from chipping at the
cutting edges 126b, 128b. Despite the fact that the cutting
edges are defined by obtuse angles, the scissors cut very well.
According to a third embodiment of the invention shown in
Figure 6, a pair of bipolar scissor blades according to the
invention includes metal blades 226 and 228. In this embodiment,
both blades 226 and 228 have a shearing surface 226f, 228f which
is substantially completely coated with a ceramic material 226g,
228g and a cutting edge 226b, 228b which is defined by an obtuse
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angle. When used in a bipolar endosurgical instrument such as
the one shown in Figure 1, the blades 226, 228 provide the smooth
operation and feel of a metal on metal cutting/shearing action.
The ceramic coatings 226g, 228g on the blades 226, 228 insure
that the shearing surfaces 226f, 228f of the blades are
electrically insulated from each other so that cautery current
may be constantly supplied throughout a cutting procedure. The
included obtuse angles of the cutting edges 226b, 228b of the
blades 226, 228 prevents the ceramic coatings 226f, 228f from
chipping at the cutting edges 226b, 228b. Despite the fact that
the cutting edges are defined by obtuse angles, the scissors cut
very well.
From the foregoing, it will be appreciated either of the
scissor blades 128, 228 may be used with any of the blades 26,
126, 226. Moreover, although not shown, the non-coated blade 26
may be provided with a 90~ or obtuse angle cutting edge if
desired to impart symmetry to the scissor blades and/or to reduce
the cost of manufacture by casting both blades in the same die.
As described in the parent application, bipolar scissor
blades may be made of a laminate of several conductive and non-
conductive materials. Figure 7 shows an example of two scissor
blades 326, 328 which are each composite laminates of conductive
and non-conductive material. Typically, the shearing surface
326f, 328f of the blades will be a ceramic material in order to
provide the metal-on-metal feel taught by the parent application.
The middle portion 326r, 328r of the laminate may be either
conductive or non-conductive and the outer portion 326q, 328q of
the laminate may be either conductive or non-conductive provided
that at least one of the middle portion and the outer portion is
conductive. In accord with the invention, the blades having
ceramic coated shearing surfaces are provided with cutting edges
defined by an obtuse angle.
A presently preferred method of making the scissor blades
according to the invention is illustrated in Figures 8a - 8c and
9. A metallic scissor blade 428 having an acute angle cutting
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edge 428a, as shown in Figure 8a, is obtained. A ceramic coating
428g is applied to the shearing surface 428f of the blade as
shown in Figure 8b. The blade 428 and the coating 428g are then
ground along a line "G" as shown in Figure 8c to form an obtuse
angle cutting edge 428b as shown in Figure 9. A second all-metal
scissor blade 426 having an acute angle cutting edge 426a is also
obtained, and the two scissor blades 426, 428 are arranged as
shown in Figure 9 so that cutting takes place at the point where
there respective cutting edges 426a, 428b meet. The former
cutting edge 428a of the ceramic coated blade is rendered
sufficiently dull and is spaced far enough apart from the cutting
edge 428b so that no cutting or tearing is effected by the former
cutting edge 428a. If desired, to further insure that cutting
occurs only at edges 426a and 428b, the metal edge 428a may be
rounded in a further grinding step.
There have been described and illustrated herein several
embodiments of bipolar endoscopic surgical scissor blades and an
instrument incorporating them. 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
conductive and non-conductive materials have been disclosed, it
will be appreciated that other materials could be utilized.
Also, while blades of specific shape and ~lmension have been
shown, it will be recognized that blades having different shapes
and ~lmensions could be used with similar results obtained.
While means for pivotally joining the blades has been shown as an
axle screw with a nut, other pivotal joining means could be used.
For example, a clevis with an integral axle pin, or a snap-in
axle pin, or a riveted axle pin could all be used. While means
for supplying each blade with a voltage has been shown as a
bipolar push rod, it will be appreciated that other means such as
a bipolar clevis and bipolar hollow tube could be used.
Individual shielded electrical conductors within the hollow tube
could also be used for this purpose. In addition, while the
electrical coupling of the conductive portion of each blade has
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14
been shown as the proximal connecting lug which connects to a
link, it will be appreciated that an electrical coupling could be
made through a two piece bipolar clevis axle. Also, while the
means for imparting scissor-like movement to the blades has been
shown as a push rod, a pull wire or other reciprocating
arrangement might be used as well. In addition, while the means
for coupling the scissor blades to the push rod has been shown as
an orthogonal lug, it will be understood that other means such as
a connecting hole could be used while achieving substantially the
same results. Moreover, while particular methods have been
disclosed in reference to laminating conductive and non-
conductive layers, it will be appreciated that other methods
could be used as well. Also, it will be appreciated that
provision of an obtuse angle cutting edge on a scissor blade
having a ceramic coating on its shearing surface may be applied
to many different types of scissor blades and the scissor blades
described herein are to be considered exemplary rather than
limiting. 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.
