Note: Descriptions are shown in the official language in which they were submitted.
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TRACK GUIDED END EFFECTOR ASSEMBLY
TECHNICAL FIELD
This invention relates to endoscopic surgical
instruments. More particularly, this invention relates to
an endoscopic forceps having a rack and pinion actuator
handle and a track guided end effector assembly.
BACKGROUND ART
Endoscopic forceps are well known in the art. These
instruments typically include a tube member and a control
member extending through the tube member. The proximal end
of the control member is typically coupled to an actuator
handle which imparts reciprocal movement to the control
member relative to the tube member. The distal end of the
tube member is typically coupled to a clevis and a pair of
forceps end effectors are pivotally mounted in the clevis.
The distal end of the control member is coupled to the end
effectors and reciprocal movement of the control member
relative to the tube member causes the end effectors to
pivot relative to the clevis and thereby open or close
relative to each other. The tube member and the control
member may be either rigid or flexible and the length of
these members will vary, depending on the application, from
several inches to several feet.
Several different kinds of actuator mechanisms are
known for use with endoscopic forceps, including a handle-
lever gripping member arrangement, and a thumb ring-spool
type device. The handle-lever arrangement includes a
stationary handle and a movable lever which is pivotally
coupled to the stationary handle. The stationary handle has
a distal finger ring and the movable lever has a proximal
thumb ring. The stationary handle is coupled to the tube
member and the movable lever is coupled to the control
member. Typically, the handle-lever mechanism is held like
a pair of scissors. Squeezing the thumb ring towards the
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finger ring pulls the control member in a proximal direction
which usually results in closing the end effectors. The
thumb ring-spool devices usually include a central slotted
shaft having a proximal thumb ring, where the displaceable
spool is slidable along the shaft and has a cross member
which passes through the slot in the shaft. The tube member
is coupled to the shaft and the control member is coupled to
the cross member of the spool. The thumb ring-spool device
is held like a hypodermic syringe. Squeezing the spool
towards the thumb ring usually results in closing the end
effectors.
Various designs for the clevis and end effectors are
also known, although the clevis is most often a U-shaped
member having an axle pin on which a pair of end effectors
is pivotally mounted. The end effectors may be cutters or
grippers. In the case of biopsy forceps, the end effectors
are typically formed to be cuplike for holding a tissue
sample which is cut or torn by the forceps.
There are many concerns in the design and manufacture
of endoscopic forceps and these concerns are often related
to the competing interests of strength versus cost of
manufacture. The materials used in most endoscopic
instruments include stainless steel and aluminum. More
recently, in disposable instruments, plastic and bronze have
been used. Manufacturing processes include molding, casting
and extrusion. Typically, the end effectors are the most
difficult part of the endoscopic instrument to manufacture
because of their small size and because they must be strong.
In cutting and biopsy instruments, the coupling of the end
effectors to the clevis, the clevis to the tube member, and
the end effectors to the control member raise additional
strength considerations since the amount of force required
to cut and/or obtain a biopsy tissue sample is relatively
high. In addition, clogging of the clevis and the tube is
always a consideration since various fluids and tissues may
enter the clevis space and hamper operation of the forceps.
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While the handle actuator is usually easy to
manufacture, due in part to its relatively large size
compared to the end effectors and the clevis, there are
several considerations which must be addressed regarding the
actuator handle. Among these considerations are smooth
action, tactile feedback, and linear motion. These
considerations are also often related to the clevis and end
effector assembly insofar as the end effectors should move
positively and smoothly in response to the movement of the
actuator handle and the actuator handle should provide
tactile feedback in response to the action of the end
effectors. The amount of movement of the handle actuator
needed to open and close the end effectors is also an
important consideration.
DISCLOSURE OF INVENTION
It is therefore an object of the invention to provide
an endoscopic forceps which has enhanced strength but is
inexpensive to manufacture.
It is also an object of the invention to provide an
endoscopic forceps having an actuator handle which imparts
true linear motion to the control member.
It is another object of the invention to provide an
endoscopic forceps having an actuator handle which transmits
positive tactile feedback to the user.
It is a further object of the invention to provide an
endoscopic forceps having an actuator handle which allows
rotation of the forceps.
Another object of the invention is to provide an end
effector assembly which has enhanced strength but is
inexpensive to manufacture.
A further object of the invention is to provide end
effectors which have enhanced strength but are inexpensive
to manufacture.
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Even another object of the invention is to provide a
clevislike coupling device which has enhanced strength but
is inexpensive to manufacture.
It is still another object of the invention to provide
a clevis which resists clogging by tissues and fluids.
It is also an object of the invention to provide a
clevis and end effectors in which the rate at which the end
effectors open and close relative to a given movement of the
actuator can be preselected.
Yet another object of the invention to provide a clevis
and end effectors in which the closing force of the end
effectors can be enhanced for cutting end effectors or
reduced for grasping end effectors.
In accord with these objects which will be discussed in
detail below, the endoscopic forceps of the present
invention includes a tube member and a control member
extending through the tube member. The proximal ends of the
control member and the tube member are coupled to an
actuator mechanism which imparts reciprocal movement to the
control member relative to the tube member. The actuator
mechanism according to the invention includes a handle part
having a stepped throughbore with a relatively small
diameter at the distal end and relatively large diameter at
the proximal end. The large diameter portion of the
throughbore has a lower slot opening and a cylindrical rack
member is slidably disposed in the large diameter portion of
the throughbore. A lever is pivotally coupled to the
stationary handle and is provided with a toothed upper
pinion which enters the slot in the large diameter portion
of the throughbore and engages the rack member. The
proximal end of the tube member is coupled to the distal
small diameter portion of the throughbore and the proximal
end of the control member is coupled to the distal end of
the rack member.
According to a preferred aspect of the invention, the
rack member is provided with a distal bore and a radial set
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screw which enters the distal bore. The control member is
preferably a push rod or wire which is coupled to the rack
member by inserting the proximal end of the push rod into
the distal bore of the rack member and tightening the set
S screw. In a rotational embodiment, a rotational ferrule is
coupled to the tube member and can be rotated relative to
the handle. When the ferrule is rotated, the tube member,
end effectors, push rod or wire, and rack member all rotate,
with the cylindrical rack member rotating in the toothed
pinion. In a non-rotational embodiment, the distal small
diameter portion of the throughbore in the handle is
preferably provided with a radial slot which extends to the
exterior of the handle. The tube member is preferably a
coil which is coupled to the handle by inserting the
proximal end of the coil into the small diameter portion of
the throughbore in the handle and inserting a staple into
the radial slot such that the staple engages turns of the
coil or a slot in the tube but permits free movement of the
push rod or wire.
The distal end of the tube member is coupled to a
clevis and a pair of end effectors are engaged by the clevis
and coupled to the distal end of the control member. For
purposes herein, the term "clevis" is to be understood
broadly as the structural apparatus which holds or guides
the end effectors, regardless of its shape and structure,
and is not to be defined in a limited manner to be limited
to U-shaped devices. The clevis according to the invention
is a cylindrical plastic or metal member formed from two
substantially identical halves. Each half of the clevis has
a proximal semi-cylindrical opening, and a distally
extending longitudinal groove which bends outward from the
longitudinal axis at the distal end of the clevis half and
forms a track for guiding movement of a respective end
effector. A portion of the clevis half has a sleeve-
receiving waist of slightly reduced outer diameter.According to one embodiment, the clevis is provided with a
WO96/02193 2 1 9 q 7 7 5 PCT~S95/08911
deformation-permitting side cut-out, and a tube engaging
bump located on an inner surface of the proximal semi-
cylindrical opening between the side cut-out and the
distally extending longitudinal groove. The two halves of
the clevis are assembled by joining the halves over the
distal end of the tube member and sliding a substantially
rigid sleeve over the waists of the halves. The sleeve is
able to assume its position over the waists due to the
deformation-permitting side cut-outs which radially yield as
the sleeve is forced over collars on the clevis halves.
When assembled in this manner, the tube engaging bump
deforms into the tube member, thereby holding the tube
member in place in the clevis. According to another
embodiment, the clevis is provided with a reduced diameter
proximal portion over which a sleeve which connects the coil
to the clevis can be crimped or otherwise attached.
Regardless of the mechanism for attaching the clevis to the
tube or coil, the distal end of the assembled clevis
presents a substantially flat circular surface except for
distal ends of the two oppositely directed outwardly bending
longitudinal grooves; each of which present a small,
substantially rectangular opening on the distal base of the
clevis and a small, substantially rectangular radial opening
adjacent to and contiguous with the base opening.
The end effectors according to the invention are
preferably identical and each has a proximal tang which is
offset from the longitudinal axis of the end effector and
which curves through the plane of the working surface of the
end effector. The tang of each end effector is received by
a respective longitudinal groove of the clevis and the end
of each tang is coupled to the distal end of the control
member. When the control member is moved distally through
the tube member, the tangs of the end effectors are guided
in their distal movement by the inner surfaces of the
grooves in the clevis and the working surfaces of the end
effectors are moved apart from each other. When the control
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member is moved proximally through the tube member, the
tangs of the end effectors are guided in their proximal
movement by the grooves in the clevis and the working
surfaces of the end effectors are moved towards each other.
S The curvature and/or the angle of the bends in the tangs
and/or the clevis grooves determine how fast the end
effectors open and close relative to a given movement of the
control member. Since the only opening of the clevis is
through the grooves and since these grooves are occupied by
the end effector tangs, the clevis is substantially sealed
from clogging by fluids or tissues.
According to preferred aspects of the invention, the
distal end of the push rod is provided with a hooked bend
and the tangs of the end effectors are provided with holes
which are engaged by the hooked end of the push rod. The
clevis is preferably provided with slots along a portion of
the longitudinal grooves for receiving the sides of the
hooked end of the push rod. The clevis is preferably molded
30% carbon fiber filled nylon and the groove arrangement
provides smooth operation and high strength.
Attachment of the clevis and end effectors to the
distal ends of the coil and push rod is preferably
accomplished by first inserting the push rod through the
tube or coil and placing the clevis sleeve over the distal
end of the tube or coil. The tangs of the end effectors are
then coupled to the end of the push rod, and the halves of
the clevis are placed around the end effectors so that the
tangs of the end effectors engage the grooves in the clevis.
Where the clevis includes tube engaging bumps, the placement
of the clevis will cause the bumps to engage the tube or
coil. The sleeve is then slid over the clevis halves.
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.
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WO96/02193 PCT~S95/08911
BRIEF DESCRIPTION OF DRAWINGS
Figure l is a broken side elevation view in partial
section of a rack and pinion actuator handle according to
the invention coupled to a coil and push rod and a track
guided end effector assembly according to the invention;
Figure la is a view similar to Figure l of a second
embodiment of an actuator handle according to the invention;
Figure 2 is an enlarged cross sectional view along line
2-2 of Figure l;
Figure 3 is an enlarged side elevation view of a clevis
half according to the invention;
Figure 4 is a top view of the clevis half of Figure 3;
Figure 5 is a proximal end view of the clevis half of
Figure 3;
Figure 6 is a distal end view of the clevis half of
Figure 3;
Figure 7 is an enlarged transparent side elevation view
of two clevis halves held together with a sleeve according
to the invention;
Figure 8 is a top view of the clevis halves of Figure
7;
Figure 9 is a proximal end view of the clevis halves of
Figure 7;
Figure l0 is a distal end view of the clevis halves of
Figure 7;
Figure ll is an enlarged top view of a first embodiment
of an end effector according to the invention;
Figure 12 is a side elevation view of the end effector
of Figure ll;
Figure 13 is an enlarged top view of a second
embodiment of an end effector according to the invention;
Figure 14 is a side elevation view of the end effector
of Figure 13;
Figure 15 is an enlarged transparent side elevation
view of the clevis of the invention coupled to the distal
end of a coil and two end effectors mounted in the clevis
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_
and coupled to the distal end of a push rod, with the end
effectors in the open position;
Figure 16 is a view similar to Figure 15, but with the
end effectors in the closed position;
Figure 17 is an enlarged transparent top view of the
clevis of the invention coupled to the distal end of a coil
and two end effectors mounted in the clevis and coupled to
the distal end of a push rod, with the end effectors in the
closed position;
Figure 18 is an enlarged side elevation view in partial
section of a second embodiment of the clevis of the
invention coupled to the distal end of a coil;
Figure 19 is an enlarged exploded top view in partial
section of the clevis of Figure 18; and
Figure 20 is an enlarged exploded side elevation view
in partial section of the clevis of Figure 18.
BEST MODES FOR CARRYING OUT THE INVENTION
Referring now to Figures 1 and 2, an endoscopic forceps
10 according to the invention includes a flexible coil 12
having a lumen 14 and a push rod or wire 16 extending
through the lumen 14 of the coil 12. A proximal actuator
mechanism 18 is coupled to the proximal ends of the coil 12
and the push rod 16 for imparting reciprocal movement to the
push rod relative to the coil. A distal end effector
assembly 20 is coupled to the distal ends of the coil 12 and
the push rod 16 and is responsive to reciprocal movement to
the push rod relative to the coil.
The actuator mechanism 18, according to the invention,
includes a stationary handle 22 and a movable lever 24. The
stationary handle 22 has a lower finger ring 26 and an upper
stepped through bore 28. The stepped throughbore 28 has a
larger diameter proximal portion 30 and a smaller diameter
distal portion 32. The larger diameter portion 30 is
provided with a lower slot opening 31 and the smaller
diameter portion 32 is provided with a radial slot 33 which
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WO96/02193 PCT~S95108911
extends to the exterior of the stationary handle 22. A
cylindrical rack member 34 is slidably disposed in the
larger diameter portion 30. The rack member 34 has a
cylindrical shaft 36 and a plurality of cogs 38 spaced apart
by defining grooves 37. The distal end of the rack member
34 is provided with a longitudinal bore 40 for receiving the
rod or wire(s) 16, and a radial bore for accommodating a
radial set screw 42 which enters the longitudinal bore 40
for holding the rod or wire(s) therein. The proximal end of
the rack member 34 is preferably provided with an electrical
connector such as a banana clip 44 for connection to a
source of cautery current (not shown).
The movable lever 24 of the actuator mechanism 18 has a
lower thumb ring 46 and an upper pinion 48. The movable
lever 24 is coupled to the stationary handle 22 by a pivot
axle 50 and is arranged so that the upper pinion 48 enters
the larger diameter portion 34 of the throughbore 28 through
the lower slot opening 31. The upper pinion 48 is curved
with a radius "r" extending from the pivot axle 50 to the
closest groove 37 and has a plurality of spaced apart teeth
52. The teeth 52 engage the spaces (grooves) 37 between the
cogs 38 on the rack member 34 as seen in Figure 1. From the
foregoing, those skilled in the art will appreciate when the
movable lever 24 is rotated about the pivot axle 50, the
pinion 48 imparts a true linear reciprocal motion to the
rack member 34.
The actuator mechanism 18 is coupled to the tube or
coil 12 and push rod or wire(s) 16 by first inserting the
proximal end of the push rod or wire(s) 16 into the bore 40
of the rack member 34 and tightening the set screw 42. The
proximal end of the tube or coil 12 is then inserted into
the smaller diameter portion 32 of the throughbore 28 past
the radial slot 33. A staple 54 (or any substantially U-
shaped member) is inserted into the slot 33 until it engages
the coil or tube 14, with the legs of the staple embedding
into the handle. According to one embodiment of the
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invention, where a coil is utilized, the legs of the staple
extend between turns of the coil (as seen in Figure 2) and
prevent the coil from being pulled out of the handle.
According to another embodiment of the invention, the cross
piece of the staple is located such that it extends between
turns of the coil to prevent the coil from being pulled out
of the handle. If desired, the legs may be similarly
arranged. Regardlessj care must be taken to avoid impeding
movement of the push rod or wire 16 through the coil 12.
According to yet another embodiment of the invention,
instead of providing a radial slot 33, two holes are
provided for the legs of the staple, which are placed to
between turns of the coil so as to prevent the coil from
being pulled out of the handle. When the staple legs are
embedded into the handle, the staple cross piece can be
flattened or rounded against the external surface of the
handle.
Figure la shows a second embodiment of the actuator
mechanism 118 which is similar in many respects to the
actuator mechanism 18 of Figure 1. In Figure la, similar
features of the actuator mechanism 118 have reference
numerals which are similar to those used with reference to
the actuator mechanism 18, but increased by one hundred. In
the second embodiment seen in Fig. la, the actuator
mechanism 118 is provided with radial groove 133 in lieu of
a staple slot 33. A rotational ferrule 154 is also provided
and is bonded or otherwise attached to the coil or tube 12.
Alternatively, a proximal portion of the coil or tube 12 is
insert molded in the ferrule 154. The ferrule 154 is
provided with a groove engaging radially inward projection
156 which engages and rides in the radial groove 133. The
ferrule is preferably made from resilient plastic and is
press fit over the actuator 118 so that the projection 156
snaps into the groove 133. The ferrule 154 is thus
rotatable relative to the actuator 118. As will be
appreciated by those skilled in the art, rotation of the
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WO96/02193 PCT~S95/08911
ferrule 154 relative to the actuator mechanism 118 will
effect a rotation of the coil 12 and thereby effect rotation
of the end effector assembly 20 (Figure 1). Rotation of the
end effector assembly will result in a rotation of the push
rod or wires 16. The rotation of the push rod or wires 16
will result in a rotation of the rack member 134 inside the
large diameter proximal portion 130 of the throughbore 128
with the preferably rounded cogs 138 rotating in the teeth
152 of the pinion 148. It will therefore be recognized that
the rack and pinion arrangement according to the invention
allows for easy rotation of the coil and push rod relative
to the actuator mechanism. The ferrule shown in Figure la
is merely exemplary. Other ferrules which may be applied to
the actuator mechanism are disclosed in co-assigned U.S.
Patents Nos. 5,176,702; 5,174,300; and 5,293,878, the
disclosures of which are hereby incorporated herein by
reference in their entireties. If desired, the groove 133
and the projection 156 may be provided with bumps and
indents (not shown) so that rotation of the ferrule is
stepped.
The end effector assembly 20, according to the
invention, includes a clevis 56 and a pair of preferably
identical end effectors 58, 59 which are seen in detail in
Figures 4 through 10. In one embodiment, the clevis 56 is
formed from two substantially identical clevis halves 60
(62) which are joined together with a stainless steel sleeve
64 as seen best in Figures 8 through 10 and described in
more detail below. Each clevis half, for example 60
(Figures 3 through 6), is a molded plastic semi-cylindrical
member. (For simplicity, only clevis half 60 is described
and referenced with numerals, since both clevis halves 60
and 62 are substantially identical.) A semi-cylindrical
opening 66 is provided at the proximal end of the clevis
half 60. A deformation-permitting side cut-out 68 is
provided in the side wall of the opening 66 and a coil
engaging bump 67 is provided in the side wall distal of the
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WO96/02193 PCT~S9S/08911
cut-out 68. A longitudinal groove 70 extends from the
distal end of the opening 66 towards the distal end of the
clevis half 60 and bends away from the longitudinal axis of
the clevis half at the distal end of the clevis half. The
groove 70 is defined by two sidewalls 72, 74 which are
substantially parallel near the opening 66 and which bend at
different rates near the distal end of the clevis half 60.
As seen best in Figure 3, the upper sidewall 72 bends
smoothly in a shallow arc 76 toward the top of the clevis
half and ends before the distal end of the clevis half 60.
The lower sidewall 74 bends up more rapidly at 78 and ends
at the distal end of the clevis half 60 with a curved
downward dip 78a. The slot 70 thereby exits the clevis half
60 through two substantially rectangular openings 80, 82.
Other than the opening 80, the distal end of the clevis half
60 is a solid semicircular surface as seen best in Figures 6
and 10. A longitudinal slot 86 is preferably provided
within the groove 70 for reasons which will be described
below. In the preferred embodiment, the outer surface of
the clevis half 60 is a substantially smooth semi- cylinder
except for a ramped proximal collar 88 and a distal collar
90 defininq a central sleevereceiving waist 92. The
proximal collar 88 is preferably provided with a conical
taper or ramp 89 to aid in the reception of the sleeve 64 as
described below. The stainless steel sleeve 64 is seated on
the waist 92 between the collars (protrusions) 88 and 90
when the clevis is assembled as shown in Figures 7 and 8.
One of the pair of identical end effectors 58 designed
for use with the clevis 56 is shown in Figures 11 and 12.
(For simplicity, only end effector 58 will be described and
referenced with numerals since both end effectors 58 and 59
are identical.) End effector 58 is a biopsy forceps end
effector and has a substantially oblate hemispherical cup
portion 96 which may be provided with a relatively sharp lip
98. A proximal tang 100 is offset from the longitudinal
axis of the cup 96 and extends substantially parallel to the
21 94775
Wo96tO2193 PCT~S95/08911
longitudinal axis of the cup 96. The proximal end of the
tang 100 is provided with a hole 102 for coupling with the
push rod as will be described in detail below. As seen best
in Figure 12, the tang 100 is shaped like a pan handle and
rises above the plane in which the lip 98 lies. A
relatively shallow curved surface 104 with a rounded notch
104a is provided on one edge of the tang and a slightly
steeper curved surface 106 is provided on an opposite edge
of the tang 100. As will be appreciated from the discussion
below, the tang is a particularly important aspect of the
end effector 58, while the cup 96 may be replaced with
virtually any type of end effector element such as a gripper
296 as shown in Figures 13 and 14, a scissors (not shown), a
serrated biopsy cup ~not shown), etc. The end effector 258
shown in Figures 13 and 14 is substantially paddle shaped
with a grooved working surface 298 for gripping. The tang
200, however, is virtually identical to the tang 100
described above having similarly curved edge 204 with
rounded notch 204a and curved edge 206.
Figure 15 through 17 illustrate how the preferred
embodiment of the clevis 56 and the end effectors 58 (59)
are assembled, how they are coupled to the coil 12 and the
push rod 16, and how they operate in response to the
actuation handle. Turning to Figure 17, it will be seen
that the distal end of the push rod 16 is bent to form a
hook 116 which engages the holes 102 in the tangs 100 of the
end effectors 58 (59). It will also be seen that the
longitudinal slots 86 in the clevis halves 60 (62) provide a
space for the hook 116 as well as a guiding track for the
push rod 16 as it is moved to the distal position shown in
Figure 15 and the proximal position shown in Figures 16 and
17.
As mentioned briefly above, the end effector assembly
20 is assembled by first inserting the push rod 16 into the
lumen 14 of the coil 12 (before the coil and push rod are
coupled to the handle as described above with reference to
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WO96/02193 PCT~S95108911
Figures 1 and 2). The clevis sleeve 64 is placed
temporarily over the distal end of the coil 12 and the two
end effectors 58, 59 are attached to the hook 116 at the
distal end of the push rod 16 as shown best in Figures 16
and 17. Next, the clevis halves 60, 62 are placed over the
tangs 100 of the end effectors so that respective tangs
reside in respective grooves 70 and the hook 116 resides in
the slots 86 and the proximal semi-cylindrical openings 66
embrace the distal end of the coil 12. In this state, the
bumps 67 press against the turns of the coil 12. The sleeve
64 is then moved off the distal end of the coil 12 and over
the conical tapers 89 of the proximal collars 88 of the
clevis halves 60, 62. As the sleeve rides up the ramps, the
proximal collars 88, due to the cut-outs 68, bend slightly
radially inward, so that the sleeve can be forced over and
past the collars 88. The sleeve 64 is then slid onto the
waist 92 of the clevis where it is secured between the
proximal and distal collars 88 and 90 (collars 88 having
resumed an unstressed position) and holds the two clevis
halves 60, 62 together with the end effectors 58, 59 between
them. As the clevis 56 and the end effectors 58, 59 are
assembled as described, the bumps 67 on the inside surface
of the clevis are deformed between coil loops by the radial
inward pressing of them against the coil. This deformation
prevents the coil from being pulled out of the clevis. Of
course, if desired, other means such as welding, cementing,
etc., can also be utilized to hold the coil in the clevis.
In fact, where the endoscopic apparatus utilizes a
laparoscopic type tube instead of a coil "tube", a different
mechanism for holding the tube in the clevis is typically
required.
Operation of the end effector assembly is best
understood with reference to Figures 15 and 16. When the
end effectors 58, 59 are in the open position as shown in
Figure 15, the push rod 16 is in the distal position.
Squeezing the lever 24 of the actuator handle 18 (Figure 1),
WO96/02193 2 1 9 ~ 7 7 ~ PCT~S95/08911
16
moves the push rod 16 in the proximal direction. The distal
hook 116 on the push rod 16 pulls the tangs 100 of the end
effectors 58, 59 by virtue of its attachment through the
holes 102 in the tangs 100. As the hook 116 moves
proximally in the slots 86, the curved surface 106 on the
tangs 100 engages the curved surfaces 76 of the sidewalls 72
of the grooves 70 in the respective clevis halves 60, 62.
The engagement of these surfaces causes the end effectors to
close to the position shown in Figure 16. It will
appreciated that the curvature of the surfaces 76, 106 will
not only determine the rate at which the end effectors
close, i.e., how much movement of the push rod 16 is needed
to move the end effectors from the open to the closed
position, but the rate of change in the rate at which the
end effectors close. For example, by properly arranging the
curvatures of the surfaces 76, 106, the end effectors can be
arranged with constant linear movement of the push rod to
accelerate, decelerate, or vary speeds in their closing
motion.
When the end effectors 58, 59 are in the closed
position as shown in Figure 16, they are opened by moving
the thumb ring 46 away from the finger ring 26 on the handle
18 (Figure 1) which moves the push rod 16 in the distal
direction. As the push rod 16 is moved in the distal
direction, the distal hook 116 moves in the slots 86 and
pushes the tangs 110 of the end effectors 58, 59 by virtue
of its attachment to the holes 102 in the tangs 100. As the
tangs 100 are pushed in the distal direction, the curved
surfaces 104 on the tangs 100 engage the surfaces 78 on the
sidewalls 74 of the grooves 70 in the respective clevis
halves 60, 62. The engagement of these surfaces causes the
end effectors 58, 59 to open to the position shown in Figure
15. It will be appreciated again that the curvature of the
surfaces 78, 104 will determine not only the rate at which
the end effectors open, but the acceleration or
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WO96/02193 PCT~S95/08911
deceleration, or speed change in the opening of the end
effectors.
From the foregoing, those skilled in the art will
appreciate that the curvature of the surfaces of the tangs
of the end effectors and of the internal clevis grooves (76,
78, 104, and 106) may be chosen to provide for different
rates and change of rates of opening and closing of the end
effectors or they may be chosen to provide that the end
effectors open and close at the same rates. It will also be
appreciated that the rates and change of rates of opening
and closing may be chosen to accommodate different types of
end effectors. For example, it may be desirable for biopsy
forceps to close quickly when taking a sample and open
slowly so that the sample is not easily lost. In addition,
in the quick closing of the biopsy forceps, in order to
provide additional force it may be desirable for the end
effectors to accelerate as they approach the closed
position.
Figures 18 through 20 show a second embodiment of a
clevis 156. The second embodiment of the clevis 156 is
substantially the same as the embodiment described above
with respect to the curved surfaces which interact with the
tangs of the end effectors. However, the clevis 156 is
different from the clevis 56 in the way that it attaches to
the distal end of the coil 12. The clevis 156 is shorter
than the clevis 56 and has a relatively small diameter
proximal part 192 which has substantially the same outer
diameter as the outer diameter of the coil 12. A stainless
steel tube 164 is used to couple the clevis 156 to the coil
12 as shown in Figure 18. The tube 154 fits over the distal
end of the coil 12 and over the proximal part 192 of the
clevis 156 and is coupled to both by either welding,
crimping, gluing, or other suitable means. It will be
appreciated that the distal portion 160 of the clevis has an
outer diameter which is substantially the same as the outer
diameter of the tube 164 after it is crimped. The tube 164
WO96/02193 2 1 q 4 7 7 5 PCT~S95108911
therefore forms a relatively smooth outer surface with the
distal portion 160 of the clevis 156. In order to
facilitate and/or enhance the coupling of the tube 164 with
the coil 12, a distal portion 12a of the coil 12 may be
ground slightly as shown in Figures 19 and 20 so that a
greater surface area of the coil is presented to the tube
164 for attachment.
There has been described and illustrated an endoscopic
forceps having a rack and pinion actuation handle and a
track guided end effector assembly. 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 tube members and control members have
been disclosed, it will be appreciated that other tube and
control members could be utilized. Also, while two specific
end effectors have been shown, it will be recognized that
other types of end effectors could be used with similar
results obtained. Moreover, while particular configurations
have been disclosed in reference to the coupling of the coil
and push rod to the actuator handle and to the clevis and
end effectors, it will be appreciated that other
configurations could be used as well. Furthermore, while
the clevis has been disclosed as being made of two
substantially identical plastic parts and held together with
a sleeve, it will be understood that different materials and
connecting means can achieve the same or similar function as
disclosed herein, and the clevis halves need not be
identical. In addition, while the invention was described
substantially in terms of an endoscopic instrument with a
coiled "tube" as is typical for a biopsy forceps device, it
will be appreciated that the rack and pinion handle can be
used with any type of endoscopic instrument, including
instruments utilizing push rods, wires, laparoscopic type
tubes, and different types of end effectors and end effector
2 i 9~775
WO96/02193 PCT~S95/08911
19
assemblies, including single acting instruments. Likewise,
the end effector arrangement which opens and closes at
desired rates and accelerations or decelerations, can be
used in conjunction with other types of endoscopic
instruments, including instruments having different types of
handle arrangements, and instruments utilizing push rods,
wires, laparoscopic type tubes, as well as single acting
instruments, scissors, etc. The end effectors need not be
identical and need not open and close at the same rates or
with the same force. 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.
