Note: Descriptions are shown in the official language in which they were submitted.
WO 95129638 ~ ~ PCTIUS95/04661
1
SURGICAL STAPLER WITH MECHANISMS FOR
REDUCING THE FIRING FORCE
Technical Field
The present invention relates generally to surgical stapling
instruments used in open and/or laparoscopic surgical procedures and more
particularly to the type of surgical stapling instruments used for
substantially
sequentially applying linear parallel rows of staggered staples through
compressed
tissue.
to
Bacl~round
Surgical stapling instruments used for substantially sequentially
applying parallel, linear rows of staggered staples through compressed living
tissue are well known in the art, and are commonly used for closure of tissue
or
15 organs prior to transection or resection, and for occlusion of organs in
thoracic
and abdominal plasty procedures. Surgical staplers of this type may be used
during an open surgical procedure where an incision is made to provide access
to
the surgical site, or during a laparoscopic surgical procedure where tissue
stapling
is accomplished through a generally cylindrical access tube.
20 Surgical staplers which substantially sequentially fire staples
typically comprise a staple housing for enclosing the staples prior to their
formation, a pusher having a cam surface, and staple drivers substantially
adjacent
each staple. As used herein, when it is said that a surgical stapler
"substantially
sequentially" fires the staples in a linear row, it is meant that the stapler
completes
25 the application of some staples in a row before the application of other
staples in
the row, as opposed to a stapler which generally simultaneously fires all of
the
staples in a row. In a stapler which "generally simultaneously" fires staples,
during at least a portion of the movement of its firing mechanism, all of the
staples
are in motion relative to the staple housing. The circular stapler disclosed
in U.S.
3o Patent No. 4,754,909 generally simultaneously fires a circular array of
staples, and
the stapler described in EPO Application No. 514 139 to Solyntjes et al.
generally
simultaneously fires a plurality of linear, parallel rows of staggered
staples.
w0 95/29638 PCT/US95/04661
i , Y s
t '..
In a stapler which substantially sequentially fires staples in a linear
row, the firing mechanism typically comprises a pusher, staple drivers
generally
adjacent staples in a staple housing and an anvil. The pusher is movable
relative
to the staple housing in a firing direction. On its leading edge, the pusher
has a
caroming surface situated at an acute, included angle with the firing
direction.
The staple drivers have cam follower surfaces for engaging the caroming
surface
to move the staple drivers in a staple formation or staple driving direction
which is
typically perpendicular to the firing direction. Movement of the staple
drivers in
the staple formation direction ejects the staples from the staple housing and
l0 presses the ejected staples against specially shaped surfaces on the anvil
to
engage, form and close the staples in tissue between the staple housing and
anvil.
In an unformed condition, staples used in a sequentially fired
stapler typically comprise a backspan and a pair of legs projecting from the
backspan that each include a sharp tissue penetrating surface. During
formation
15 of an individual staple, the tips first pass through tissue and then engage
the
specially shaped surface of the anvil. The force required to initially buckle
or
bend the staple legs when they engage the anvil is relatively greater than the
force
required to pierce tissue.
When properly formed, the staples assume a substantially "B"
2o shaped configuration. Improperly or only partially formed staples may
result in a
variety of adverse consequences for a patient, such as inadequate hemostasis,
excessive bleeding or a weakened staple line which could result in dehiscence
of
the anastomosis or leakage.
In the present context, the phrase, "formation force" pertains to
25 - the force required to apply a staple. The phrase "initial maximum
formation
force" refers to the initial maximum force encountered during formation of a
staple which corresponds to the initial buckling or bending of the legs.
During the
formation of staple loops, a second maximum formation force is encountered
that
is also substantially greater than the force required to penetrate the tissue.
The
30 second maximum formation force may be greater than the initial maximum
formation force. The second maximum formation force corresponds to the
formation of the legs into loops after the buckling of the legs, but before
the legs
WO 95129638 PCT/1J595/04661
engage each other or the backspan, or before the final formation of the legs
into
loops.
It is also believed that a third maximum formation force may be
encountered during the final formation of the staple. The third maximum
formation force is believed to correspond to staple legs engaging either each
other
or the backspan, or to the increasing bending forces encountered by the
buckling
of the staple legs on an ever shortening effective beam length. The third
maximum formation force is also relatively greater than the maximum force
required to pierce tissue. Graphs of the firing force versus pusher
displacement
are found in U.S. Patent No.'s 3,494,533 and 4,767,044, but these graphs do
not
illustrate the third maximum formation force that was discovered by applicants
and mentioned above.
Figure 42 is a graph of the formation force curve in pounds versus
the pusher stroke in inches for a prior art titanium staple which was slightly
overcrimped in simulated thin tissue. The staple was a staple designed
generally
for use in a stapler as shown in EPO Application No. 514 139 to Solyntjes et
al.
Each of the first, second and third maximum formation forces are referenced as
#1, #2 and #3.
The prior art is replete with mechanisms designed to reduce the
overall formation force experienced by the surgeon in firing all of the rows
of
staples in the stapler. For example, U.S. Patent No. 3,499,591 illustrates a
stapler
with pusher devices staggered so that peak forces for staples are not
simultaneously encountered. European Patent Application No. 545029 discloses
further attempts to reduce the operative effort.
A general analysis of the relationship between the pusher, pusher
driver and anvil reveals that by reducing the angle between the caroming
surface
of the pusher and the firing direction (or conversely, increasing the angle
between
the caroming surface of the pusher and the staple driving direction), the
force
encountered by the surgeon may be reduced. U.S. Patent No.'s 3,079,606 to
3o Bobrov et al. and 3,315,863 to O'Dea illustrate sequentially fired staplers
with
pushers having caroming surfaces at small included angles with the firing
direction. The illustrated angles appear to be less than about twenty (20)
degrees.
W O 95/29638
PCTIUS95/04661
~. a,_ ~' ~,.".:
A distal or nose portion for the staple housing is required to house
the distal portion of the pusher while the proximal portion of the pusher
completes the firing of the distalmost staple in a staple row. When the pusher
caroming surface forms a shallow angle with the firing direction, the distal
or nose
portion of the staple housing is relatively lengthy. Such staplers encounter
problems when used in a surgical procedure which requires the stapler to
staple
tissue in a remote position which is not readily accessible to a surgeon, as
such
staplers require relatively lengthy distal end portions (or "noses") of the
staple
housing to accommodate the small angled pusher. Examples of such procedures
l0 include deep pelvic or thoracic cavity procedures where space is a limiting
factor.
The distal end portion of a stapler may limit the access of the
stapler to the tissue to be stapled. For example, tissue such as bone or
adjacent
blood vessels may prevent proper placement of such a stapler on tissue. A
stapler
with a lengthy distal end portion is also believed to be di~cult to maneuver
in
cramped or tight spaces at least in part due to the lengthy distal end
portion.
These problems are only exacerbated when the sequentially fired
stapler comprises a laparoscopic stapler, as the surgeon's access to the
tissue to
be stapled is even further restricted due to the access tube. It is
particularly
important in laparoscopic surgery to provide a cartridge as small as possible
in
order to maximize the maneuvering room between the distal end of the access
tube and the tissue to be stapled.
U.S. Patent No. 4,596,351 to Fedotov et al. discloses a stapler
having a pusher with a curvilinear caroming surface. The angle between the
curvilinear caroming surface of the pusher of Fedotov et al. and the firing
direction constantly changes rendering it difficult to accurately predict the
effective angle encountered during the various stages of staple formation.
It is also noted that the pushers of the GIA - 60 surgical stapler
(generally available from U.S. Surgical Corporation) appear to comprise first
and
second linear ramming surfaces, but do not include a third linear camroing
3o surface. This stapler is generally designed for use in laparoscopic
surgery.
Other approaches to the problem of reducing the firing force
encountered by a surgeon comprise surgical staplers that are manually fired
but
include a) a mechanism for providing a mechanical advantage, or b) a powered
W O 95129638
PCT/US95I04661
instrument which utilizes stored energy (such as gas stored in a cylinder).
Staplers with mechanical advantage comprise the 3 cm Endostapler known as the
Endo GIA-30, available from U.S. Surgical Corporation ofNorwalk, Connecticut
and the 6 cm Endostapler known as the Endopath Linear Cutter 60 available from
Ethicon, Inc. of Somerville, New Jersey. However, these types of staplers are
expensive to manufacture, complex and do not provide a surgeon with direct
feedback as to how the position of the firing lever travel relates to the
length of
tissue that has been stapled (and optionally cut).
Another approach to the problem of reducing the firing force
to experienced by a surgeon is shown in U.S. Patent No.'s 5,083,695 and
5,141,144.
Figure 18 illustrates a problem overcome by these types of staplers. The
stapler 5
illustrated in Figure 18 comprises a stapler substantially as shown in U. S.
Patent
No. 4,863,088. With that stapler 5, the surgeon must push with enough force to
overcome not only the firing force of the staples and fiictional drag of the
pushers
i5 and drivers, but also the frictional side or binding load created by
pressing on the
knob 6 at a location spaced from the axis 4 of the firing rod ii. The binding
load is
shown in Figure 18 as the moment MF and is described by the following
equation:
MF FF H where:
FF firing force (pounds); and
2o H off center height (the distance between the point where the
force FF is applied on the knob 6 and the axis 4 in Figure 18).
Notably, since the knob 6 is mounted on the side of the stapler 5,
when a surgeon presses on the knob 6 in a convenient manner, a moment is
created about the firing rod 11. If the moment is large enough, it may even
cause
25 the pushers to engage the staple housing increasing the friction
encountered by
the firing assembly of the device. Thus, it can be seen that the moment may
increase the firing force encountered by a surgeon.
The staplers shown in U.S. Patent No.'s 5,083,695 and 5,141,144
have a firing handle body capable of being fired by simultaneously pressing on
3o both sides of a firing button. The firing button may be located on both
sides of
the stapler to assist in eliminating any appreciable moment M,.. However, in
order
to fire the stapler in this manner, surgeons will use both hands. The surgeon
should also push equally on both sides of the firing button to avoid a
resultant
2I~~t~~
WO 95/29638 PCTIUS95/04661
(c
moment on the firing rod. Such.a technique is inconvenient during a
laparoscopic
i ,~, ;~
surgical procedure where fyp'ically only one of the surgeon's hands is
available for
firing the stapler.
Another firing force issue arises when the surgical stapler is
designed to apply six parallel rows of .staples as opposed to the typical
stapler
which applies only four rows of staples. For example, in laparoscopic surgery
where hemostasis and air leakage of lung tissue are particularly important, it
may
be desirable to add the fifth and sixth rows of staples.
Figure 16 schematically illustrates a prior art, six row staple
pattern applied by the laparoscopic GIA stapler available from U. S. Surgical
of
Norwalk, Connecticut. However, if substantially parallel pushers are used to
apply that arrangement of staples, first 2, then 4, then 2, then 4 staples are
applied. This may lead to a "chatter" problem or a "bumpy" feel to the
instrument
as peak firing forces fluctuate considerably. Assuming the pushers of the
stapler
are not staggered, it also requires the surgeon to exert a formation force
sufficient
to simultaneously form four staples.
I?isclosure ofthe Invention _.
The present invention provides a surgical stapler instrument for
2o applying linear parallel rows of staples through compressed living tissue.
The
surgical stapler comprises a handle portion having surfaces adapted to be
manually grasped by a surgeon; a cartridge retention portion and an anvil
retention portion. An approximation means mounts the cartridge and anvil
retention portions for relative movement between a closed position in which
the
- anvil and cartridge retention portions are in closely spaced relationship
for
clamping tissue to be stapled therebetween and an open position in which the
anvil
and cartridge retention portions are spaced farther from each other than in
the
closed position. The anvil retention portion includes an anvil with a
plurality of
specially shaped surfaces.
The cartridge retention portion has a staple housing for enclosing a
plurality of staples in substantially parallel, linear rows. Each of the
staples have a
backspan and a pair of legs projecting from the backspan. The legs buckle
during
WO 95129638 2 i 8 5 I ~ 9: PCT/US95/04661
7
formation of the staples into their desired "B" shape. The staple housing has
staple drivers adjacent staples. The cartridge retention portion includes a
plurality
of pushers each having at least three linear ramming surfaces. The pushers may
comprise a portion of the staple housing or alternatively the stapler itself.
The staple housing has a plurality of longitudinally extending
pusher slots for receiving the pushers to afford movement of the pushers in a
firing direction between prefired and fired positions, and a plurality of
driver
channels for receiving the staple drivers to afford movement of the staple
drivers
in a staple driving direction between pre-eject and ejected positions.
to Each of the staple drivers has a cam follower surface for engaging
the linear ramming surfaces of a pusher to move the staple driver from the pre-
eject toward the ejected position to substantially sequentially eject the
staples
from the staple housing and press the ejected staples against the specially
shaped
surfaces of the anvil to engage, form and close staples in tissue clamped
between
15 the staple housing and the anvil.
According to one aspect of the present invention, the three linear
caroming surfaces of the pushers comprise a) a first ramming surface for
engaging
a staple driver during initial tissue penetration of a staple; b) a second
ramming
surface for engaging a staple driver during initial buckling of the legs of a
staple;
2o and c) a third ramming surface for engaging a staple driver after the legs
of a
staple have been initially buckled and during the closing of the staple in
tissue.
The first caroming surface forms a first included angle with the staple
driving
direction. The second ramming surface forms a second included angle with the
staple driving direction that is greater than the first included angle. The
third
25 ramming surface forms a third included angle with the staple driving
direction that
is different than the first and second included angles.
According to another aspect of the present invention, the proximal
portion of a stapler comprises first and second sides, top and bottom
portions, a
firing handle channel extending between the sides to define a space between
the
30 top and bottom portions, and finger engagement surfaces that are sized and
shaped to be engaged by the fingers of a stapler firing hand of a surgeon. The
stapler further includes a firing handle mounted in the firing handle channel
for
movement in the firing direction between.prefired and fired positions. The
firing
WO 95129638 - PCTIUS95104661
B'
handle has digit engagement surfaces dimensioned and shaped to be receive a
digit
such as the thumb of the firing hand of a surgeon,
The firing handle channel is'.'sized and shaped to afford passage of
at least one digit of the surgeon's hand from one of the first and second
sides,
through the space, to the other of the first and second sides to afford manual
grasping of the firing handle. This feature of the stapler provides an
ambidextrous
quality in that the stapler is conveniently fired by both left and right
handed
surgeons.
The stapler includes a firing rod between the firing handle and the
1o pushers. The firing rod has proximal and distal portions for transmitting a
firing
force from the firing handle to the pushers to move the pushers in the firing
direction. The proximal portion of the firing rod defines a proximal portion
firing
axis substantially parallel to the firing direction.
The firing handle and proximal portion of the firing rod are
15 constructed and arranged to afford transmission of a force directly along
the
proximal portion firing axis so that the proximal portion of the firing rod
may
remain substantially free of a moment caused by the surgeon pressing on the
firing
handle to move the firing handle from the pre-fired toward the fired position.
The features of the staplers described above may be utilized in any
2o stapler which fires a plurality of parallel rows (2, 3, 4, 5 etc.) of
staples in
compressed tissue. According to another aspect of the present invention, the
stapler comprises the cartridge retention portion having a staple housing for
enclosing six rows of staples in substantially parallel, linear rows. The six
rows
are spaced laterally across the staple housing such that any line drawn
laterally
25 across the staple line crosses at least three staples.
In another embodiment of a six row surgical stapler, the stapler
comprises the cartridge retention portion having a staple housing for
enclosing six
adjacent rows of staples in substantially parallel, linear rows. The distance
between adjacent staples in the same row defines a staple pitch. In this
3o embodiment the six rows are spaced such that each row is longitudinally
offset
from all of the other rows. Preferably, the staples in each of the rows are
longitudinally offset at least 1/6 of the pitch P from any staple in any of
the other
WO 95129638 ~ ~ g 51~ ~ PCTlUS95104661
9
rows. More preferably, one of the rows is longitudinally offset 1/3 of the
pitch
from each of the adjacent rows.
In another aspect of a surgical stapler for firing six parallel rows of
staples in compressed tissue, the stapler comprises six rows of staples that
are
separated into a first set of three parallel linear rows and a second set of
three
parallel linear rows by a centerline or knife travel line. Each of the three
parallel
linear rows of staples in the first set are spaced such that it is
longitudinally offset
from the other two rows of staples in the first set. Similarly, each of the
three
parallel linear rows of staples in the second set are spaced such that it is
to longitudinally offset from the other two rows of staples in the second set.
Preferably, in this embodiment, at least one of the rows of staples in the
first set is
longitudinally aligned traps the pushers in the distal end portion of the
staple
housing.
As mentioned above, the trapping means comprises at least one of
the pushers having a hook surface, the staple housing including a trap surface
in
substantially the distal end portion of the staple housing for receiving the
hook
surface of the pusher when the pusher is in the fired position, and biasing
means
for biasing the pusher vertically away from the tissue to be stapled so that
the
hook surface of the pusher is biased toward the trap surface of the housing.
2o Optionally, the stapler may include means mounting the knife for
vertical movement between an extended position with the knife projecting
vertically beyond the tissue engagement surface of the staple housing and a
retracted position with the knife spaced fivther from the anvil than in the
extended
position. In this embodiment, the knife includes a bearing surface, the staple
housing has a guide channel having a cutting motion portion for receiving the
bearing surface of the knife as the knife moves between the prefired and fired
positions, and the guide channel has an abutment portion situated
approximately
perpendicular to the cutting motion portion of the guide channel for abuting
the
bearing surface of the knife to restrict longitudinal movement of the knife
from the
fired toward the pre-fired position. Biasing means are present for vertically
biasing the knife from the extended toward the retracted position.
In another preferred embodiment, the stapler includes a one-way
coupling between the firing rod, pushers and knife which affords reciprocal
WO 95/29638 r~ ~ g PCTIUS95I04661
!U
movement of portions of the firing rod between prefired and fired positions
but
which only affords movement of tie pushers and knife from the prefired toward
the fired position. This embodiment provides a tactile indication to a surgeon
that
V
the stapler has been fired as the resistance fa movement of the firing
assembly is
different for fired and unfired staple housings.
The features of the present invention may be with one of the rows
of staples in the second set. More preferably, the first set of rows is a
mirror
image of the second set of rows.
Yet another aspect of the present invention comprises a surgical
to stapler having a firing means movable in a firing direction between
prefired and
fired positions to substantially sequentially eject the staples in a row from
the
staple housing and press the ejected staples against the specially shaped
surfaces
of the anvil to engage, form and close staples in tissue clamped between the
staple
housing and the anvil. The stapler includes a firing handle and a firing rod
operatively associated with the firing means for movement between the prefired
and fired positions, and an optional knife for cutting tissue. The stapler has
a
means that is operatively associated with the firing means and mounts the
knife
for movement between a pre-fired position in which the knife is located in the
proximal portion of the staple housing and a fired position in which the knife
is
located in the distal portion of the staple housing. The stapler includes a
novel
trapping means for trapping the knife in-the distal end portion of the staple
housing in the fired position and for restricting return movement of the knife
from
the fired toward the prefired position once the firing means has been moved
from
the prefired to the fired position. Preferably, the trapping means includes an
z5 interference member for physically blocking return movement of the pushers
from
the fired to the prefired position.
Preferably, the firing means comprises: a) staple drivers adjacent
staples, and a plurality of pushers each having a caroming surface, b) the
staple
housing having a plurality of longitudinally extending pusher slots adapted to
receive the pushers to afford movement of the pushers in the firing direction,
and
c) a plurality of driver channels for receiving the staple drivers to afford
movement of the staple drivers in a staple driving direction between preeject
and
ejected positions. In this embodiment the trapping means utilized in surgical
W0 95129638 PCTIUS95104661
staplers used in either open or laparosc pic surgical procedures. Some of the
aspects of the present invention are particularly useful in staplers utilized
in
laparoscopic surgical procedures.
Brief Description of the Drawing
The present invention will be further described with reference to
the accompanying drawing wherein like reference numerals refer to like parts
in
the several views, and wherein:
Figure 1 is a side view of a first embodiment of surgical stapling
1o instrument according the present invention showing the cartridge and anvil
of the
stapler in an open position, with middle portions of the stapler omitted to
emphasize details of proximal and distal portions of the stapler, and with the
distal
portion of the stapler enlarged relative to the proximal portion to illustrate
details
of the distal portion;
15 Figure 2 is a side view of the surgical stapling instrument of Figure
1 showing the cartridge and anvil of the stapler in a partially closed
position, and
with the distal portion of the stapler enlarged relative to the proximal
portion to
emphasize details of the distal portion;
Figure 3 is a side view of the surgical stapling instrument of Figure
20 1 showing the cartridge and anvil of the stapler in a closed position, and
with the
distal portion of the stapler enlarged relative to the proximal portion to
emphasize
details of the distal portion;
Figure 3A is a side view of the surgical stapling instrument of
Figures 1 through 3 which illustrates the proximal and distal ends at the same
size;
25 Figure 4 is an enlarged detailed view of the stapler of Figure 2
taken generally at the circled portion of Figure 2;
Figure S is a sectional view of the stapler of Figure 4 taken
approximately along lines S-S of Figure 4;
Figure SA is an enlarged perspective view of portions of the
3o stapler of Figure 1 which illustrates a clevis;
Figure 6 is a side view of a second embodiment of surgical stapling
instrument according the present invention showing cartridge and anvil
portions
of the stapler in an open position and with middle portions of the stapler
omitted
WO 95129638 ~ PCTIUS95/04661
92
to emphasize details of proximal and distal portions of the stapler, and with
the
*.
distal portion of the stapler enlaeged >~elative to the proximal portion in
order to
emphasize details;
Figure 7 is a side view of the stapler of Figure 6 with the cartridge
and anvil of the stapler in a closed position;
Figure 8 is a sectional view ofthe stapler ofFigure 7 taken
approximately along lines 8-8 of Figure 7;
Figure 9 is a sectional view of the stapler ofFigure 7 taken
approximately along lines 9-9 of Figure 7;
1o Figure 10 is an enlarged side view of a distal portion of the stapler
of Figure 6;
Figure 11 is an enlarged side view of a distal portion of the stapler
of Figure 7;
Figure 12 is an enlarged side view of the second embodiment of
15 surgical stapler according to the present invention with the cartridge and
anvil in
an emergency open position;
Figures 13 through 15 sequentially illustrate the operation of a
firing mechanism of a stapler according to the present invention wherein:
Figure 13 is a side view of a firing mechanism of a stapler
20 according to the present invention illustrating the positions of a pusher,
staple
driver and staple as the staple initially pierces tissue;
Figure 14 is a side view of a firing mechanism of a stapler
according to the present invention illustrating the positions of a pusher,
staple
driver and staple as the legs of the staple begin to buckle;
25 Figure 15 is a side view of a firing mechanism of a stapler
according to the present invention illustrating the positions of a pusher,
staple
driver and staple as the loops of the staple are forming;
Figure 16 is a schematic view of portions of six parallel rows of
staples in a pattern created by a prior art stapler or optionally a stapler
according
30 to the present invention;
Figure 17 is a schematic view of portions of six parallel rows of
staples in a pattern created by a stapler according to the present invention;
WO 95129638 PCTIUS95/04661
l3
Figure 18 is a perspective view of a prior art surgical stapler which
illustrates a moment created about the firing rod;
Figure 19_ is a side view of a surgical stapler according to the
present invention which illustrates the position of a firing handle in a
prefired
position in hidden lines and in a fired position in solid lines;
Figure 20 is a top view of the surgical stapler of Figure 19;
Figure 21 is a top view of another embodiment of stapler
according to the present invention;
Figures 22 through 27 are side views of the stapler of Figure 21
and sequentially illustrate the positions of a pusher and knife during the
firing of
the stapler wherein:
Figure 22 illustrates the pusher and knife in a prefired position;
Figure 23 illustrates the pusher slightly advanced during an initial
portion of the firing stroke and the knife in the same longitudinal position
as
shown in Figure 22;
Figure 24 illustrates the pusher and knife after they have been
advanced a significant portion of the firing stroke;
Figure 25 illustrates the knife and pusher as they have been
advanced slightly more distally than in Figure 24 with the knife beginning to
2o descend vertically toward the pusher along an abutment surface;
Figure 26 illustrates the pusher advanced slightly beyond its
position in Figure 25 and the knife descended toward the bottom of the
abutment
surface;
Figure 27 illustrates the pusher and knife after they have been
advanced to a distalmost position and after a lockout device has been
actuated;
Figures 28 through 35 are side views of another embodiment of a
stapler according to the present invention and sequentially illustrate the
positions
of a pusher and knife during the firing of the stapler wherein:
Figure 28 illustrates the pusher and knife in a prefired position;
Figure 29 illustrates the pusher slightly advanced during an initial
portion of the firing stroke and the knife after it has vertically ascended a
ramp
surface on the staple housing;
W095129638 ~ PCTIUS95/04661
Figure 30 illustrates tl~e_pttsher and knife after they have been
c,,, _.
advanced a significant portion of the firing stroke;
Figure 31 illustrates the knife and pusher as they have been
advanced slightly more distally than in Figure 30 with the knife beginning to
descend vertically toward the pusher along an abutment surface;
Figure 32 illustrates the pusher advanced slightly beyond its
position in Figure 31 and the knife descended toward the bottom of the
abutment
surface;
Figure 33 illustrates the pusher and knife after they have been
to advanced to a distalmost position and after a lockout device has been
actuated;
Figure 34 is a schematic illustration of portions of a second
embodiment of staple rows according to the present invention which simulates a
top view with the staples rotated about ninety degrees about their backspans
and
with the spacing between the rows exaggerated to illustrate details;
15 Figure 35 is a schematic view of portions of a third embodiment of
staple rows according to the present invention which illustrates six parallel
rows
of staples in a pattern;
Figure 36 is a schematic view of portions of a fourth embodiment
of staple rows according to the present invention which illustrates six
parallel
2o rows of staples in a pattern;
Figure 37 is a schematic side view of an optional firing rod and
knife assembly according to the present invention;
Figure 38 is a schematic illustration ofthe assembly ofFigure 37
taken approximately at detail 3838 ofFigure 37 which illustrates the direction
of
25 movement of the assembly during firing and retraction strokes with arrows;
Figure 39 is a schematic view of a surgical stapler for use in an
open surgical procedure that may include several aspects of the present
invention,
which illustrates the cartridge and anvil of the stapler in a closed position;
Figure 40 is a schematic view of the stapler of Figure 39 which
3o illustrates the cartridge and anvil of the stapler in a closed position;
Figure 41 is a side view of the surgical stapling instrument of
Figures 6 and 7 which illustrates the proximal and distal ends of the stapler
at the
same size;
W0 95129638 PCTIUS95/04661
Figure 42 is a firing force curve for an individual staple through
simulated thin tissue, which illustrates first, second and third maximum
formation
force peaks;
Figure 43 is a side view of a first embodiment of an optional,
unformed staple for use in the stapler according to the present invention;
Figure 43A is a first example of a cross-section taken about the
cross section lines of Figure 43;
Figure 43B is a second example of a cross-section taken about the
cross section lines of Figure 43;
1o Figure 43C is a third example of a cross-section taken about the
cross section lines of Figure 43;
Figure 44 is a side view of the staple of Figure 43 in a formed
condition;
Figure 45 is a side view of a second embodiment of an optional,
15 unformed staple for use in the stapler according to the present invention;
Figure 46 is a side view of the staple of Figure 45 in a formed
condition;
Figure 47 is a side view of a third embodiment of optional formed
staple for use in the stapler according to the present invention;
2o Figure 48 is a top view of the staple of Figure 47;
Figure 49 is a plan view of a dimple of an anvil for forming the
staple of Figure 48;
Figure 50 is a side view of a fourth embodiment of an optional,
unformed staple for use in the stapler according to the present invention;
25 Figure 51 is a side view of the staple of Figure 50 with the staple in
a formed condition; and
Figure 52 is a sectional view ofthe staple ofFigure 51 taken
approximately along lines 52-52 of Figure 51.
30 Detailed Description
Referring now to Figures 1 through 5 of the drawing, there is
shown a first embodiment of surgical stapling instrument according to the
present
WO 95/29638 ~ PCTIU595/04661
invention, generally designated by )reference numeral 10. The surgical stapler
10
is designed to apply staples to compresSe'~.'tissue, preferably during a
laparoscopic
surgical procedure.
The stapler 10 may comprise a single use disposable stapler, a
reusable surgical stapler or a reloadable disposable surgical stapler. As used
in
this application, the phrase "reusable surgical stapler" means a surgical
stapler
which may not only be fired several times on the same patient (with, for
example,
the use of replaceable cartridges or staple housings), but may also be
sterilized
and reused on a different patient. Such a stapler stands in opposition to what
is
to known in the art as a "disposable surgical stapler". While a reloadable
disposable
surgical stapler may be reused several times on the same patient, a disposable
surgical stapler is not meant to be sterilized or used on a plurality of
patients. A
single use disposable stapler is designed to be used (fired) once and disposed
after
that single use.
In general, the stapler 10 comprises a proximal portion including a
handle portion having surfaces 12 adapted to be manually grasped by a surgeon,
and a distal portion including a cartridge retention portion 14 and an anvil
retention portion 16.
The anvil retention portion 16 comprises an anvil having specially
2o shaped surfaces 7 (best seen in Figures 13-I S) the function of which will
be
described in greater detail below. The anvil may comprise a permanent anvil or
a
replaceable anvil. As used in this application, the phrase "replaceable anvil"
means an anvil which may be removed from the stapler by medical personnel, and
then replaced with a different, sterilized or refurbished anvil. A permanent
anvil is
fixedly attached to an anvil retention portion of the stapler and is not
designed to
be replaced during the life of the stapler. An anvil is described in published
Canadian Patent application No. 1,284,551 and Australian patent document No.
589,001. The anvil may be constructed from, for example, a medical grade
stainless steel.
Between the proximal and distal portions, the stapler 10 has a
housing 17 having exterior surface 18 terminating in distal end 19. The
exterior
surface 18 is preferably substantially cylindrical and is sized and shaped to
engage
WO 95129638 PCTIU595/04661
l7
the interior surfaces of an access tube of a trocar assembly. The housing 17
is
elongate and defines a longitudinal axis L (see Figure 3A) for the stapler 10.
Preferably, the housing 17 is rotatable about the longitudinal axis L
of the stapler 10 relative to the proximal portion of the stapler. A collar 59
and
bearing sleeve 57 allow the housing 17 to rotate relative to the proximal
portion
of the stapler 10. The collar 59 may have exterior surfaces such as ribs for
enhancing the manual grasping of the collar by a surgeon.
When the stapler 10 is used during a laparoscopic surgical
procedure, the distal portion of the stapler 10 is threaded through the
interior
1o surfaces of the access tube of a trocar (such as the trocar in U.S. Patent
No.
5,152,754). Preferably, the access tube engagement surface 18 is dimensioned
(sized and shaped) to engage or abut the interior surfaces of the access tube
(not
shown) of a trocar to restrict leakage of fluid from the abdominal cavity of a
patient. Preferably the access tube engagement surface 18 is cylindrical with
an
15 outer diameter slightly less than the inner diameter of the access tube.
The stapler 10 has an approximation means for mounting the
cartridge and anvil retention portions 14 and 16 for relative movement
between:
(1) a closed position (Figure 3) in which the cartridge and anvil retention
portions
are in closely spaced relationship for clamping tissue to be stapled
therebetween
2o and ( . 2) an open position (Figure 1) in which the cartridge and anvil
retention
portions 14 and 16 are spaced farther from each other than in the closed
position.
In the open position, tissue to be stapled may be received between the
cartridge
and anvil retention portions 14 and 16.
Generally, the approximation means comprises three assemblies
25 which are best seen in Figures 4 and 5. The first assembly comprises a
cartridge
frame 22. The cartridge frame 22 preferably has a Unshaped channel adapted to
closely receive exterior surfaces of a staple housing 112 so that the stapler
10 may
comprise a reusable or reloadable disposable stapler.
As discussed above, the housing 17 is rotatable about the
30 longitudinal axis of the stapler 10 relative to the proximal portion of the
stapler
10. However, the cartridge frame 22 is mounted on the stapler so that the
cartridge frame 22 does not move longitudinally or rotate relative to the
housing
17. The cartridge frame 22 has opposite first and second side bearing surfaces
23
WO 95129638 ~ ~ PCTIUS95/04661
and 25 which are laterally spaced abou the longitudinal axis of the stapler 10
(see
Figure SA). A ' . y' t.
The second assembly of the approximation means comprises a
longitudinally movable assembly. The longitudinally movable assembly is
operatively associated with a locking lever 28 that is movable between an open
(Figure I) and a closed position (Figure 3). Pin 29 mounts the locking lever
28 for
pivotal movement relative to the housing 17 about the pin 29. Optionally, the
distal portion of the locking lever 28 may be designed to slightly interfere
with the
collar 59 when the locking lever 28 is in the closed position so that, when
the
to locking lever 28 is in the closed position, the interference resists
rotation of the
housing 17 relative to the proximal portion.
Torsion spring 31 biases the locking lever 28 toward the open
position. Latch 33 engages retention surfaces on release lever 35 to secure
the
locking lever 28 in the closed position against the bias of spring 31. To open
the
stapler 10, a surgeon moves the release lever 35 laterally relative to the
locking
lever 28 to release the latch 33.
Linkage 37 and pins 38 translate the pivotal movement ofthe
locking lever 28 into longitudinal, axial movement of collar 39 (Compare
Figures
I and 3). Bearing ring 41 connects the collar 39 to a control shaft 42 so that
the
2o collar 39 does not move longitudinally relative to the control shaft 42.
The
control shaft 42 and collar 39 are axially reciprocable within and relative to
the
housing 17. However, bearing ring 41 does afford rotational movement of the
collar 39 relative to the control shaft 42 when the proximal portion of the
stapler
is rotated relative to the housing 17.
As best seen in Figure SA, Unshaped clevis 44 fixedly attaches a
pair of transversely spaced guide members 46 (Figures 4 and 5) to the control
shaft 42 so that the guide members 46 do not move relative to the control
shaft
42. The first and second bearing surfaces 23 and 25 of the cartridge frame 22
receive and abut their respective guide members 46 and assist in constraining
the
3o guide members 46 to substantially axial longitudinal movement relative to
the
cartridge frame 22.
The guide members 46 each have a first, proximal control groove
51 and a second, distal control groove 53, the operation of which will be
WO 95f29638 PC1YUS95104661
tq
described in greater detail below. To close the stapler 10, the control shaft
42 is
moved proximally from the position in Figure 1 to the position in Figure 3
substantially linearly and parallel to the axis of the stapler 10. Reversing
the
direction of the control shaft 42 (e.g. distal movement of the shaft 42) opens
the
stapler 10.
The third assembly of the approximation means of the stapler 10
comprises an anvil assembly which includes the anvil retention portion 16. The
anvil assembly includes a proximal portion 55 sandwiched between the guide
members 46 and terminating in proximal end 56. The anvil also has distal end
58.
1o Proximal post 62 and fulcrum post or axle 64 are fixedly attached to and
project
laterally or transversely (relative to the longitudinal axis of the stapler
10) from
spaced positions on the proximal portion 55 of the anvil assembly.
The fulcrum post or axle 64 is sized and shaped to be received in
the distal control grooves 53 of the guide members 46. The fulcrum post 64
i5 affords substantially seesaw motion of the anvil assembly relative to the
distal
control grooves 53 of the guide members 46.
As best seen in Figures 4 and 5, the proximal post 62 projects
through the proximal control grooves 51 of the guide members 46 and is sized
and shaped to be received in limiter slots 66 of the cartridge frame 22.
Unlike the
2o fulcrum post 64 which only projects sufTiciently laterally to be received
in the
control grooves 53, the proximal post 62 projects laterally into opposite
anvil
limiter slots 66 in the cartridge frame 22.
The limiter slots 66 are generally perpendicular to the longitudinal
axis of the stapler 10 which limits the longitudinal movement of the anvil
relative
25 to the housing 17 (and cartridge frame 22). The limiter slots 66 do,
however,
afford movement of the proximal post 62 in a direction generally perpendicular
to
the longitudinal axis (vertically in Figures 1-5) so that the anvil may
substantially
seesaw about fulcrum post 64 relative to second control groove 53.
The shapes of the first and second control grooves 51 and 53 are
3o important to control the motion of the anvil retention portion 16 as it
moves from
an open position (Figure 1) to a partially closed position (Figure 2) and
finally to a
closed position (Figure 3). Figures I through 3 show preferred embodiments of
those shapes. For purposes of this discussion of the preferred embodiment, the
WO 95129638
PCTIUS95104661
ao
anvil may be divided into a leading portion 71 and a trailing portion 73, and
the
positions of the locking lever 128 iri~y be described as sequentially
proceeding from
an open position (Figure 1) to a partially closed position (Figure 2) and then
to a
closed position (Figure 3).
During the movement of the locking lever 28 from the open to the
partially closed position, the proximal post 62 is moved by leading edge
closure
portion 82 of first control groove 51 from a vertically lower position (Figure
1)
toward a vertically higher position (Figure 2) in the limner slot 66. The
leading
edge closure portion 82 causes the anvil to substantially seesaw about the
fulcrum
to post 64 as the fulcrum post 64 is moved by an initial surface 83 of second
control
groove 53. The substantial seesaw movement of the anvil allows the leading
portion 71 of the anvil to move toward the closed position more rapidly than
the
trailing portion 73.
Referring now to Figures 2 and 3, during movement of the locking
15 lever 28 from the partially closed position to the closed position, the
proximal
post 62 is moved by trailing edge closure portion 86 of first control groove
51
from the vertical higher position (Figure 2) to a vertical lower position
(Figure 3)
in the limner slot 66. At approximately the same time, the fulcrum post 64 is
moved by a final motion surface 88 of second control groove 53. During the
2o movement of the locking lever 28 from the partial closed position to the
closed
position, the trailing portion 73 of the anvil closes more rapidly than the
proximal
portion 71. In the preferred embodiment shown, the anvil substantially pivots
about anvil stop 89 during the movement of the lever lock 28 from the partial
closed position to the closed position. This motion resists extrusion of
tissue
z5 from between the cartridge retention and anvil portions 14 and 16 and out
the
distal end of the stapler 10 to beneficially ensure that tissue remains
clamped
between the cartridge retention and anvil portions 14 and 16.
The first and second control slots 51 and 53 also include opening
surfaces 92 for positively moving the anvil from the closed toward the open
3o position. These surfaces allow a surgeon to positively exert force on the
anvil to
move it toward the open position by moving the locking lever 28 from the
closed
to the open position, as opposed, for example to a system that relies solely
on the
bias of a spring to open the stapler. This feature also avoids binding of the
anvil
WO 95129638 ~ PCT/US95I04661
and cartridge portions in the closed position when the stapler 10 is used to
staple
thick or resilient tissue. Optionally, this feature allows the surgeon to use
the
stapler as an active tissue dissector.
The movement of anvil from the open position (Figure 1) toward
the closed position (Figure 3) is referred to as "tip to tail" closure as
initially the
leading portion 71 of the anvil moves toward the closed position more rapidly
than the trailing portion 73, and then the relative speeds of closure of the
leading
and trailing portions 71 and 73 are reversed. Preferably, the leading portion
71
reaches a fully closed position prior to the trailing portion 73. This motion
is
to believed to provide desirable clinical results as the initial closure of
the distal
portion resists extrusion of tissue from between the cartridge retention and
anvil
portions of the stapler.
The stapler 10 also includes means for holding and firing a plurality
of staples. The firing means comprises means for sequentially firing a
plurality of
staples in a plurality of linear rows. Optionally,- the stapler 10 may include
a
blade or knife 110 for cutting tissue between applied rows of staples. Once
the
approximation means is closed, the firing means is used to eject, form and
close
the staples in tissue. An example of a firing means for the stapler 10 may be
seen
in figures 1-5, 13-15 and 21-27.
The cartridge retention portion 14 of the stapler 10 has a staple
housing 112 for enclosing a plurality of staples 114 in substantially
parallel, linear
rows (Figures 16, 17 and 34). Typically, the staple housing 112 is removable
from the cartridge retention portion 14 and replaceable with a replacement
staple
housing 112 rendering the stapler 10 a reusable or reloadable disposable
stapler.
The staple housing 112 may be replaced with a different staple housing so that
the
stapler 10 may be refired. This may be accomplished by including a detent and
detent groove assembly (not shown) on the staple housing 112 and the cartridge
frame 22, and optionally bifurcating the firing assembly which is described in
greater detail below.
A staple 114 has a backspan 115 and a pair of legs 116 projecting
from the backspan 115. As discussed in greater detail above, the legs are
buckled
during formation ofthe staples 114. As an example not intended to be limiting,
WO 95/29638 PCTIUS951046G1
the staple 114 may include a wire diameter of 9.8 or 9.4 mils, and may be
construced from a material such as titanium.
The staple housing 112 also includes a plurality of staple drivers
120 situated adjacent staples 114. The stapler 10 also includes a plurality of
pushers 118 each having at least three linear ramming surfaces 1, 2 and 3. The
pushers 1 I S may be reusable and integral with a firing rod 90 as would be
recognized by one of ordinary skill in the art. Alternatively, the pushers 118
may
be replaced with each different staple housing 112 in a manner discussed below
with reference to Figures 37-38.
1o Reference is now made to Figure 9 with the understanding that,
although Figure 9 is a cross-section of the stapler shown in Figures 6-12, the
cross section is similar to a cross-section that may be taken on the stapler
shown
in Figures 1-5. The staple housing 112 has a plurality of longitudinally
extending
pusher slots 121 adapted to receive the pushers 118 to afford movement of the
15 pushers in a firing direction (the direction of the arrow 119 in Figures 13-
I S)
between prefired (Figure 21) and fired (Figure 27) positions. The staple
housing
112 has a plurality of driver channels 124 for receiving the staple drivers
120 to
afford movement of the staple drivers 120 in a staple driving direction (the
direction of the arrow 126 in Figures 13-IS) between preeject (Figure 13) and
2o ejected (Figure 15) positions.
Each of the staple drivers 120 have a cam follower surface 122 for
engaging the linear catnming surfaces 1, 2 and 3 of pusher 118 to move the
staple
driver 120 from the preeject toward the ejected position to substantially
sequentially eject the staples 114 from the staple housing 112 and press the
25 ejected staples 114 against the specially shaped surfaces 7 of the anvil to
engage,
form and close staples 114 in tissue 8 (Figures 13-IS) clamped between the
staple
housing 112 and the anvil.
The first ramming surface 1 forms a first included angle A,> with
the staple driving direction 126. The second ramming surface 2 forms a second
3o included angle A2 with the staple driving direction 126 that is greater
than the first
included angle Al. The third ramming surface 3 forms a third included angle A3
with the staple driving direction 126 that is different than the first and
second
W095129638 ~ ~ PCT/U595104661
as
included angles 8, and 8~. The included angles (theta 1, 2 and 3; 6,, 82 and
A3)
that the linear caroming surfaces 1, 2 and 3 form with the staple driving
direction
126 operate to reduce the amount of longitudinal projection of the staple
housing
112 beyond the distalmost staple 114 in a row and to reduce the firing force
encountered by a surgeon. The angles (theta 1, 2 and 3; Ai, 62 and 6s) also
operate to reduce the amount that the stapler projects beyond the distal end
19 of
the housing 17.
Figures 13 through 15 sequentially illustrate the forming and
closing of staple 114 in tissue 8. With reference to Figure 13, the positions
of the
to pusher 118, staple driver 120 and staple 114 are shown when the staple 114
is
initially piercing tissue 8. At this point, movement of the pusher 118 in the
firing
direction 119 is translated into movement of the staple driver 120 in the
staple
driving direction 126 by engagement between the first caroming surface I and
the
cam follower surface 122. The force required to pierce the tissue 8 is small
relative to the forces encountered later in the staple forming operation.
Thus, the
angle 6i> may be relatively small in order to reduce the overall length of the
pusher 118 and staple housing 112.
Preferably, the first included angle 9i, is between about forty-five
(45) degrees and about sixty (60) degrees. More preferably, the first included
2o angle is about sixty (60) degrees to reduce the overall length of the
staple housing
112.
Figure 14 illustrates the positions of a pusher 118, staple driver
120 and staple 114 just as the legs 116 of the staple 114 engage the specially
shaped surfaces 7 of the anvil and begin to buckle. At this point, movement of
the
pusher 118 in the firing direction 119 is being translated into movement of
the
staple driver 120 in the staple driving direction 126 by the interaction of
the
second caroming surface 2 and the cam follower surface 122. As discussed
above, an initial maximum formation force is encountered at approximately this
point. As a result, the angle A2 is greater than the angle 91, to reduce the
overall
so resultant firing force experienced by the surgeon. The angle A2 is
preferably
between about seventy-three (73) degrees and about seventy-eight (78) degrees.
It should be noted that a linear caroming surface in this range provides a
~1~5I'~~
WO 95/29638 PCT/US95104661
. .2 y
predictable engagement angle with the staple driver 120 during the time when
the
initial maximum formation force for,aataple is encountered, as opposed to a
,: , : ,. .
curvilinear pusher where the effective engagement angle between the pusher and
staple driver direction is constantly changing. More preferably Az is about
seventy-five (75) degrees.
Figure 15 illustrates the positions of the pusher 118, staple driver
120 and staple 114 as the distal ends of the legs 116 of the staple 114 are
deformed along specially shaped surfaces 7 of the anvil and form loops.
Generally, just after the legs 116 initially buckle, the formation force for
an
l0 individual staple is reduced, but it is nevertheless greater than the force
required
to pierce tissue 8. A second maximum formation force is thereafter encountered
as discussed in the background section of this document.
When the second maximum formation force of the staple 114 is
encountered, movement of the pusher 118 in the firing direction 119 is
translated
i5 into movement of the staple driver 120 in the staple driving direction 126
by the
interaction of the third camming surface 3 and the cam follower surface 122.
The
angle 63 is greater than the angle 81, to reduce the overall firing force
experienced
by the surgeon, but is typically less than the angle 92 so that the overall
length of
the staple housing 112 and pusher I 18 may be reduced. The angle 83 is
preferably
20 between about sixty-seven (67) degrees and about seventy-two (72) degrees.
In a
preferred embodiment, the angle 63 is about sixty-nine (69) degrees.
From the above it can be seen that each linear surface 1, 2, 3 of the
pusher 118 addresses a discrete portion of the staple formation curve (see
Figure
42). For example, the initial linear surface 1 corresponds to the initial
tissue
25 penetration of the staple, the linear surface 2 corresponds to the buckling
of the
staple legs and the third linear surface 3 corresponds to the terminal portion
of the
staple formation operation.
As discussed above, a third maximum formation force may be
encountered subsequent to the positions'of the elements shown in Figure 15.
3o Optionally, the pusher 118 may include a fourth linear camming surface (not
shown) forming an angle 0a, (not shown) that is greater than the angle 93 to
accommodate the third maximum formation force.
W095/29638 ~ PCT/U595104661
a5
The firing assembly also includes a firing handle 94 designed to
reduce the firing force encountered by the surgeon. Reference is now made to
Figures 19 and 20 which schematically illustrates the location of the firing
handle
94 on the stapler 10.
The proximal portion of the stapler 10 has first 95 and second 97
sides, top 96 and bottom 98 portions and proximal 101 and distal 103 ends. A
firing handle channel 104 extends between the sides 95 and 97 and ends 101 and
103 to define a space between the top and bottom portions 96 and 98. At the
distal end 103, the proximal portion of the stapler 10 has finger engagement
1o surfaces 91 that are sized and shaped to be conveniently engaged by the
fingers of
a stapler firing hand of a surgeon.
The firing handle 94 is mounted in the firing handle channel 104
for movement in a firing direction between prefired (Figures 1, 2 and 3 and
Figure
19, dashed lines) and fired positions (Figure 19, solid lines). The firing
handle
15 channel 104 is sized and shaped to afford passage of at least one digit of
the
surgeons's hand (such as the surgeon's thumb) from one of the sides 95 and 97
to
the other of sides 95 and 97. The firing handle 94 has thumb engagement
surfaces
99 dimensioned and shaped to receive the thumb of the firing hand of a surgeon
so that the stapler 10 may be fired in a motion that is similar to the motion
that
2o may be used to eject fluid from a common syringe. The thumb engagement
surfaces 99 are preferably designed so that the stapler 10 may be fired by
either
hand of a surgeon, thereby giving the firing assembly of the stapler 10 an
ambidexterity.
The firing handle 94 is fixedly connected to a firing rod 90 that is
25 situated between the firing handle 94 and the pushers 118. Figures 37 and
38
illustrate an optional one-way adapter 87 (described in greater detail below)
that
transmits the firing force from the firing rod 90 to the pushers 118. The
optional
one-way adapter afl'ords placement of the pushers 118 in the staple housing
112
so that they may be replaced with different staple housings when the stapler
is a
30 reloadable disposable or a reusable stapler. The firing rod 90 transmits a
firing
force from the firing handle 94 to the pushers 118 to move the pushers 118 in
the
firing direction.
WO 95/29638 ~ PCTIUS95104661
A proximal po'ttibn o~the firing rod is illustrated in Figures I-3 and
19-20 by reference character 901. As best seen in Figure 1, when the firing
handle 94 is in the prefired position, at least a portion of the proximal
portion of
the firing rod 901 is located within the firing handle channel 104 and between
the
proximal and distal ends 101 and 103 of the proximal portion of the stapler.'
The
proximal portion of the firing rod 901 defines a proximal portion firing axis
34
illustrated in Figures 19 and 20. The proximal portion firing axis 34 is
substantially parallel to the firing direction 119. It may be seen in Figures
1-3 that
the proximal portion of the firing rod 901 is rotationally connected to the
rest of
1o the firing rod 90 so that when the proximal portion of the stapler 10 is
rotated
relative to the housing 17, the proximal portion of the firing rod 901 may
rotate
relative to the rest of the firing rod 90.
As best seen in Figures 19 and 20, the firing ' handle 94 and
proximal portion of the firing rod 901 are constructed and arranged to afford
transmission ofa force FF directly along the proximal portion firing axis 34.
Since
there is substantially no space between the point of application of the force
F. (the
position where the surgeon places his or her thumb) and the proximal portion
firing axis 34, the proximal portion of the firing rod 901 remains
substantially free
of a moment caused by the surgeon pressing on the firing handle 94 to move the
firing handle from the prefired (Figure 19 dashed lines) to the fired position
(Figure 19 solid lines). This arrangement of structure reduces the fiictional
resistance of the firing assembly by a substantial amount and thus reduces the
resultant force experienced by a surgeon.
The stapler 10 also includes a means for preventing the firing
handle 94 from moving from the prefired position toward the fired position
until
the cartridge and anvil retention portions 14 and 16 are moved from the open
toward the closed position. As best seen in Figures 1-3, the proximal portion
of
the stapler 10 includes a rocker arm pivotally mounted by pin 61 for movement
between a) a blocking position (Figures 1 and 2) which restricts movement of
the
3o firing handle 94 from the prefired toward the fired position, and b) a free
movement position (Figure 3) which affords movement of the firing handle 94
from the prefired toward the fired position. A leaf spring 63 biases the
rocker arm
toward the blocking position.
W O 95/29638 f ' ' PCT/US95/04661
f z~s~~~~
a~
The firing handle 94 has notch surfaces 67 for receiving blocking
surface 68 of the rocker arm when the rocker arm is in the blocking position.
The
rocker arm also includes lever lock abutment surface 65 for engaging surfaces
on
the locking lever 28 when the lever lock is in the closed position (Figure 3).
When the locking lever 28 moves from the partially closed position (Figure 2)
to
the closed position (Figure 3), surfaces on the locking lever 28 engage the
lever
lock abutment surface 65 on the rocker arm and cause the rocker arm to rotate
counterclockwise in Figures 2 and 3 against the bias of spring 63 from the
blocking to the free-movement position. The rocker arm restricts movement of
l0 the firing handle 94 from the prefired toward the fired position unless the
cartridge retention and anvil retention portions are in the closed position.
Optionally, the stapler 10 may include the firing assembly depicted
in Figures 21-27. The staple housing 112 depicted in Figures 21-27 is elongate
to
define a longitudinal axis substantially parallel to the axis L (Figure 3A).
The
staple housing 112 has tissue engagement surface 75, and proximal 76 and
distal
77 end portions. The staple housing 112 also has a plurality of longitudinally
extending pusher slots 121 adapted to receive pushers 118 to afford movement
of
the Pushers 118 in a firing direction between prefired (Figures 21 and 22) and
fired (Figure 27) positions, and a plurality of driver channels 124 for
receiving the
2o staple drivers 120 to afford movement of the staple drivers 120 in the
staple
driving direction 126 between preeject and ejected positions.
The firing rod 90 and firing handle 94 are operatively associated
with the pushers 118 for movement between the prefired and fired positions.
The
stapler 10 optionally has a trapping means for trapping either the knife 110
or
both the knife 110 and pushers 118 in the distal portion 77 (e.g.
substantially
adjacent the distal end of the staple housing 112) of the staple housing 112
in the
fired position. The trapping means also prevents return movement of either the
knife 110 or preferably both the knife 110 and pushers 118 from the fired
(Figure
27) toward the prefired (Figures 21 and 22) position once they have been moved
3o from the prefired to the fired position. The trapping means physically
blocks
movement of either the knife 110 or both the knife 110 and pushers 118 from
the
fired toward the prefired position.
WO 95/29638 PCTIUS95/04661
Generally the elongate stap housing 112 defines a vertical
direction (the direction of the arrow 76 in Figure 22). In Figures 22-27, the
vertical direction is substantially perpendicular to the longitudinal axis of
the
staple housing 112. ~; ;t ..
In the preferred:embodiment, the trapping means comprises at least
one of the pushers 118 (and preferably all four pushers) having an
interference
member, preferably a hook surface 79, and the staple housing 112 having a trap
surface 78 in substantially the distal end portion 77 of the staple housing I
12 for
receiving the hook surface 79 of the pusher I 18 when the pusher 118 is in the
to fired position. The trapping means also preferably includes a biasing
means, such
as an interference fit between the pushers I 18 and the bottom portion of the
staple
housing 112 forming the slot 121, for biasing the pushers 118 vertically away
(downward in Figure 22) from the tissue to be stapled and for biasing the hook
surface 79 of the pusher I 18 into engagement with the trap surface 78 of the
staple housing 112. Alternatively, the biasing means may comprise engagement
between the camming surface of the pusher 118 and ramped surface 69 of the
staple housing 112 which moves the pusher 118 away from the stapled tissue
(see
Figures 26 and 27) so that the hook surface 79 may engage the trap surface 78.
The stapler 10 may optionally include the knife 110 that is
2o mounted for longitudinal movement between prefired (Figure 22) and fired
(Figure 27) positions. The knife I 10 is also mounted for vertical movement
between a) an extended position (Figure 22) with the knife 110 projecting
vertically beyond the tissue engagement surface 75 of the staple housing 112
so
that it may cut tissue between applied rows of staples, and b) a retracted
position
(Figures 26 and 27) with the knife I 10 less exposed than in the extended
position.
Preferably, in the retracted position, at least a substantial portion of the
knife 110
is retracted within the staple housing 112 to reduce the risk of exposure of
medical personnel who handle the spent housing 112.
To accomplish the longitudinal and vertical movement of the knife
110, the knife 110 may include a generally cylindrical bearing surface 48. The
knife is sized and shaped to ride in a guide channel of the staple housing
112. The
guide channel has a cutting motion portion 47 for receiving the bearing
surface 48
as the knife 110 moves between the prefired and fired positions. The guide
WO 95129638 PCTlUS95/04661
channel also has an abutment portion 49 situated approximately perpendicular
to
the cutting motion portion 47 o~'the guide channel.
When the pushers 118 and knife 110 are in the fired position, the
pushers 118 are prevented from moving proximally due to engagement between
the hook surface 79 and trap surface 78. In event that the hook surface 79 is
inadvertently released from trap surface 78, engagement between abutment
portion 49 and the bearing surface 48 of the knife 110 would restrict
longitudinal
(proximal) movement of the knife 110 from the fired toward the prefired
position.
If the knife 110 and pushers 118 are connected to each other as they typically
are,
1o the engagement between abutment portion 49 and the bearing surface 48 of
the
knife 110 also beneficially prevents return movement of the pushers 118.
Preferably, the knife 110 is vertically biased downwardly from the extended
toward the retracted position by a biasing means such as an interference fit
with
surface 47 created during assembly. Once surface 47 is passed, the knife 110
is
moved downwardly in the Figures to the retracted position by the biasing
means.
White the firing rod 90, pushers I 18 and knife may comprise a
unitary monolithic element, the firing rod 90, pushers 118 and knife may
optionally be associated by means of a one-way coupling 87. The one-way
coupling 87 affords reciprocal movement of the firing rod 90 (and firing
handle
94) between prefired and fired positions. When the stapler includes the
trapping
means discussed above,. the pusher I 18 and knife 110 are only movable from
the
prefired to the fired position as the trapping means traps them in the fired
position.
Figures 37 and 38 illustrate one example of the one way coupling
87. During the movement of the firing rod 90 from the prefired toward the
fired
position, the one-way adapter 87 abuts the knife 110 and pusher 118 assemblies
and transmits the firing force to those elements. once the pushers I 18 and
knife
110 reach their distalmost position, the pushers 118 and knife 110 are trapped
in
that position by the trapping means. Because the pushers 118 and knife 110 are
3o trapped, the adapter 87 affords separation of the firing rod 90 from the
pushers
118 and the knife 110 when the firing handle 94 is moved from the fired toward
the prefired position.
CA 02185154 2005-10-14
This one-way coupling 87 affords repeated movement of the firing
handle 94 between the prefired and fired positions. However, the difference in
resistance to the movement of the firing handle 94 operates as a tactile
feedback
to the user signalling that the pushers 118 and/or knife 110 have moved to the
fired position, and that the staple housing 112 is empty and should be
replaced.
The staple housing 112 may optionally include lockout device,50.
The structure and function of a lockout device 50 is described in published
PCT Document NO. WO US 94/03192.
Figures 28 through 33 illustrate portions of another embodiment of
to surgical stapler generally designated by reference character I OA which has
many
parts that are essentially the same as the parts of the stapler I 0 shown in
Figures
21-27 and which have been identified by the same reference numeral to which
the
suffix "All has been added.
Like the stapler shown in Figures 21-27, the stapler 10A has a
staple housing 112A with tissue engagement surface 75A, proximal 76A and
distal 77A end portions and trap surface 78A. The stapler 10A also has a
plurality
of pushers 1 I 8A with hook surfaces 79A. The operation of the pushers 118A is
similar to the operation of the pushers 118 described above.
Like the knife I 10, the knife 1 10A includes a knife bearing surface
48A. Like the staple housing I 12, the staple housing I 12A has a guide
channel
1
with a cutting motion portion 47A and abutment portion 49A with similar
operations. Unlike the stapler 10, in the stapler IOA, the knife 1 IOA is
initially in
a retracted position (Figure 28) which eliminates the need for a protective
cover
and reduces the exposure of the knife 110A. When the knife I 10A is moved from
the prefired toward the fired position, engagement between the journal
surfaces
49A of the knife 11 OA and a camming surface 45 on the staple housing 112A cam
the knife 1 10A from the retracted toward the projecting position.
Referring now to Figure 21, the pushers 118 of the stapler 10 are preferably
substantially aligned longitudinally to reduce the overall length of the
staple
3o housing 112 past the distalmost staple in a row. This arrangement also
reduces
the longitudinal projection of the stapler 10 past the distal end 19 of the
housing
19. Also preferably, the stapler 10 includes four pushers which may be
utilized to
apply either four or six parallel rows of staples. When the stapler 10
includes six
W095129638 ~ , PCTIUS95104661
3I
parallel rows of staples, an additional pair of pushers 118 may be added to
the
stapler or, alternatively, two of the pushers 118 may be required to fire two
adjacent rows of staples. As is well known in the art, this may be
accomplished
by using a plurality of staple drivers each of which are adapted to engage
two,
adjacent staples in adjacent rows of staples.
One example of a staple pattern 125 that may be applied by the
stapler 10 is illustrated in Figure 16 Staple pattern 125 is substantially
symmetrical
about the path 85 of the knife I 10. If a knife 110 is not present in the
stapler 10,
reference character 85 refers to the centerline of the six parallel rows of
staples.
io When the staple pushers 118 are substantially parallel or aligned
relative to the longitudinal axis of the stapler (as shown in Figure 21), a
first,
preferred embodiment of staple pattern 130 for use in the stapler 10 is shown
in
Figure 17. The staple pattern 130 shown in Figure 17 has a proximal end 131
and
a distal end 133. Any line drawn transverse to the longitudinal axis of the
staple
15 pattern between the ends 131 and 133 will cross at least three staples. In
contrast, lines 129 of pattern 125 only intersect two staples.
When the staple pushers 118 are substantially parallel or aligned relative to
the longitudinal axis of the stapler, the staple pattern 130 is preferred to
the staple
pattern 125 as, with the staple pattern 130, the pushers 118 are not required
to
2o simultaneously overcome the initial maximum formation force of more than
three
staples. In contrast, with the staple pattern 125, the initial maximum
formation
force of first two, then four, then two etc. staples are encountered by the
pushers.
This is believed to increase the resultant maximum force encountered by a
surgeon. It is also believed to contribute to an inconsistent firing force
25 experienced by the surgeon as the surgeon fires the staple line.
A second, preferred embodiment of staple pattern for the stapler
is shown in Figure 34 and generally designated 140. That staple pattern has a
proximal end 141 and a distal end 142, and six adjacent rows numbered 151-156.
The staple to staple spacing within each rows is substantially identical and
is
3o defined as the pitch. Each of the rows 151-156 is longitudinally offset
from an
adjacent row by a fraction of the pitch. For example, row one 151 may be
offset
from row two 152 by 1/2 of the pitch. The third row 153 is preferably offset
one
WO 95/29638 ~ ~ ~ PCT/US95104661
half of the offset distance of rows,~one I51 and two 152 (e.g. I/4 of the
pitch).
The staple line 140 is symmbtrical about the centerline or knife travel line
85.
The centerline 85 separates the staple rows I51-156 into a first set
131-153 and a second set 154-156. Each of the rows in the first set 151-153
are
s offset from the other two rows in the first set. Additionally, each of the
rows in
the second set 154-156 are offset from the other two rows in the second set.
However, note that row 151 is not longitudinally offset from row 154. Instead,
rows 151 and 154 are longitudinally aligned. Preferably, the first set of rows
151-
153 is a mirror image of the second set of rows 154-156 about the centerline
85.
1o A third preferred embodiment of staple pattern for the stapler 10 is
shown in Figure 35 and generally designated 140A. That staple pattern has a
proximal end 141A and a distal end 142A, and six adjacent rows numbered 151A-
156A. Each of the rows 151 A-156A is longitudinally offset from all of the
other
rows in the pattern including adjacent rows.
15 The staple to staple spacing within each row ISIA-156A is identical
and is illustrated as P, the staple row pitch. On each half of the cartridge
centerline 85A the two pairs of three rows (151A-153A and 154A-156A) are
longitudinally offset relative to an adjacent row by 1/3 ofthe pitch (1/3 x
P).
Rows 153A and 154A are offset by 1/2 of this amount, or 1/6 of the pitch (1/6
x
ao P).
When the staple pushers 118 are substantially parallel or aligned
relative to the longitudinal axis of the stapler, the staple pattern 140A is
preferred
from a firing force standpoint to the staple pattern 125 because the pushers
118
do not encounter more than one initial maximum formation force at the same
25 time. By separating the occurrences of the maximum formation forces, the
overall
force encountered by the surgeon is reduced and the forces are smoother (more
uniform and constant) than the pattern 125.
The preferred staple row pitch is about 0.156 inches. The
longitudinal offset between rows 1 S 1 A and 152A is preferably about 0.052
inches.
3o Between rows 152A and 153A the preferred offset is about 0.052 inches. The
longitudinal offset between rows 153A and 154A is about 0.026 inches and the
offset between rows 154A and 155A as well as between rows I SSA and 156A is
preferably about 0.052 inches. The distance between backspans in adjacent rows
W0 95J29638 PCTIUS95/04661
33
is preferably about 0.040 inches. The distance between rows 153A and 154A is
preferably about 0.080 inches to provide room for movement of the knife along
axis 85A.
A fourth preferred embodiment of staple rows according to the
present invention is shown in Figure 36. Like the pattern 140A, in the pattern
shown in Figure 36, the staple to staple spacing within each row 151B-156B is
identical and is defined as P, the staple row pitch. The pattern has a pair of
ends
including proximal end 141B and distal end 142B. Also like the pattern 140A,
in
the pattern shown in Figure 36, each of the rows 151B-156B are offset relative
to
to all of the other rows in the pattern.
Assuming that pitch remains constant, Figures 35 and 36 illustrate two of
several combinations of stagger patterns according to the present invention.
Generally speaking, the force considerations between the rows shown in Figures
35 and 36 are similar, but one stagger pattern may have desirable clinical
advantages over another.
Figures 43-48 and 50-52 illustrate optional embodiments of staples
for use with the staplers of the present invention which are believed to
restrict the
amount of the third maximum formation force mentioned in the Background
section of this document. Figure 43 illustrates a first optional embodiment of
staple 300 for use with the staplers according to the present invention which
is
believed to be particularly useful for stapling thin tissue. The staple 300
has a
backspan 301, and legs 302 with tips 303. Unlike prior art tips which are
created
by a blanking operation that occurs at an angle perpendicular to the plane of
the
staple, the tips 303 are formed from a blanking process which is significantly
less
than perpendicular to the plane of the staple. The tips 303 present an edge
contact to the anvil dimple and more importantly to the backspan when it is
crimped over thin tissue. This edge contact affords easy slide off of the
staple top
face from the backspan 301 which reduces the third maximum formation force.
Figures 43A-43C illustrate optional cross-sections which may be
3o coined into the backspan 301. Figure 43A illustrates an oval cross-section
305,
Figure 43B a triangular or offset ramp cross-section 306, and Figure 43
illustrates
an arcuate cross-section 307 with a cam angle surface. These enhancements are
W095/29638 ~, PCT/US95I04661
3
believed to cause the deflecting tip 303 to ove away from the backspan 301 at
a
much lower force than the prior art flattened backspan.
Figures 45 and 46 illustrate a second embodiment of optional staple 310
for use with a stapler according to thin present invention. The staple 310
includes
E.."
a backspan 311 with a groove 315, and legs 312 with tips 313. The groove 316
which is shown in only one of many potential shapes (i.e. square, triangular,
bowed, etc.) provides additional travel for the staple tips 313 in order to
prevent
contact with the backspan 311 even in thin tissue. This groove 316 would also
serve to stabilize the staple 310 as it nests in a molded slot in the driver.
to Figures 47 and 48 illustrate a third embodiment of optional staple
320 for use with the stapler according to the present invention. The staple
320
includes a backspan 321, legs 323 and tips 324. Figure 49 illustrates an anvil
dimple 322 that is fabricated at a slightly offset angle to the staple line
axis. This
combination always forces the staple tips to the same side of the backspan and
helps to reduce the third maximum formation force. Notably, if the sides of
the
anvil dimple shown in Figure 49 are substantially parallel but offset from the
firing
direction, then the anvil dimple may assist in forming the staple shown in
Figure
44.
Figures 50-52 illustrate a fourth embodiment of optional staple 330
for use with the staplers according to the present invention. The staple
includes a
backspan 331 with a lateral displacement 332, and legs 333 with tips 334. This
feature allows the tips 334 of the staple 330 to avoid contact with the
backspan
331 when used with a prior art dimple. Although the amount of offset may be
practically limited by the width of the staple housing staple slot, there may
be
sufficient room to displace the backspan at least one-half of the staple wire
diameter.
Optionally, the stapler 10 may include a flushing channel 9 having
a flush port 3 (Figure 1). If the stapler 10 comprises a reusable stapler
designed
to be sterilized, the flushing port 3 may assist in cleaning and sterilizing
the
3o internal elements of the stapler 10.
Figures 6 through 12 and 41 illustrate portions of another
embodiment of surgical stapler generally designated by reference character 200
which has many parts that are essentially the same as the parts of the stapler
10
W 0 95129638 ~ ~ PCTlUS95104661
shown in Figures 1-5 which have been identified by the same reference numeral
to
which the suffix "B" has been added.
The proximal portion of the stapler 200 is substantially identical to
the proximal portion of the stapler 10 except that the stapler 200 does not
have a
5 torsion spring 31. Like the stapler 10, the stapler 200 has cartridge and
anvil
retention portions 14B and 16B. A significant difference between the staplers
10
and 200 is that the stapler 200 has a different approximation means than the
stapler 10. Like the stapler 10, the approximation means of the stapler 200
comprises three assemblies which are best seen in Figures 8 and 10-12.
1o The first assembly comprises a cartridge fi-ame 22B that is fixedly
mounted relative to the housing 17B in a manner such that the cartridge fisme
22B does not move relative to the housing 17B. Of course, like the stapler 10,
in
the stapler 200, the housing 17B may rotate relative to the proximal portion
ofthe
stapler, but the housing 17B does not move longitudinally or rotate relative
to the
cartridge frame 22B. The cartridge frame 22B has opposite first and second
side
bearing surfaces 23B and 25B which are laterally spaced about the longitudinal
axis of the stapler 200.
The second assembly of the approximation means for the stapler
200 comprises a longitudinal movable assembly. The longitudinal movable
2o assembly is operatively associated with locking lever 28B and control shaft
42B
and is movable between an open position (Figures 6 and 10) and a closed
position
(Figures 7 and 11).
A clevis (similar to the clevis 44 shown in Figure SA) fixedly
attaches a pair of transversely spaced guide members 46B to the control shaft
42B
so that the guide members 46B do not move relative to the control shaft 42B.
The first and second bearing surfaces 23B and 25B of the cartridge frame 22B
receive and abut their respective guide members 46B and assist in constraining
the
guide members 46B to substantially axial longitudinal movement relative to the
housing 17B and cartridge frame 22B.
3o The guide members 46B each have a first, proximal control groove 201
and a second, distal control groove 203. To close the stapler 200, the control
shaft 42B is moved proximally from the position in Figure 6 to the position in
Figure 7 substantially linearly and parallel to the axis of the stapler 200.
WO 95129638 PCTIUS95104661
3~
Reversing the direction of the control shaft 42B (e.g. distal movement of the
shaft
42B) opens the stapler 200.
The third assembly of the approximation means of the stapler 200
comprises an anvil assembly which includes the anvil retention portion 16B.
The
anvil assembly includes a proximal portion 204 sandwiched between guide
,..., .
members 46B and terminating in a proximal 'end. The anvil assembly also has a
distal end. Proximal post 21 I and distal post 212 project laterally or
transversely
from spaced positions on the sides of the proximal portion 204 and are fixedly
attached to the proximal portion of the anvil 204.
1o The proximal post 21 I is sized and shaped to be received in the
substantially longitudinally extending slot 201 of the guide member 46B. The
proximal post 211 aftbrds pivotal movement of the anvil relative to the guide
member 46B. The distal post 212 is sized and shaped to be received in the slot
203. The post 211 is mounted in the anvil and indexed into the cartridge frame
i5 22B. The post 211 restricts longitudinal movement of the anvil relative to
the
housing 17B and cartridge frame 22B.
The stapler 200 includes a torsion spring 220 having first 221 and
second 222 ends. The first end 221 abuts the housing 17B and the second end
abuts the proximal portion 204 of the anvil. The torsion spring 220 biases the
2o anvil toward the open position. Latch 33B engages retention surfaces on
release
lever 35B to secure the locking lever 28B in the closed position against the
bias of
torsion spring 220. Preferably, in the embodiment shown, the spring 220 does
not
communicate with the lever 28B.
The torsion spring 220 provides an indexing location for a disposable
25 cartridge pusher assembly. The torsion spring 220 also provides a detent
for the
cartridge/staple housing as it is inserted. The spring 220 provides a detent
to give
the user a tactile 'click' when cartridge/staple housing has been properly
inserted.
The shapes of the first and second control grooves or slots 201 and
203 control the motion of the anvil retention portion 16B as it moves from an
30 open to a closed position. Preferred shapes of the slots 201 and 203 are
illustrated. The groove 201 extends substantially longitudinally and affords
pivotal movement of the anvil relative to the guide member 46B about post 211.
W 0 95/29638 PCT/US95/04G6 r
~18a~.5~
The groove 203 includes clos ng cam portion 217 which cams the
post 212 (and thus the cartridge retention portion 16B) to the closed position
when the guide members 46B are moved proximally relative to the anvil. The
groove 203 also has positive opening cam portion 227. Figure 12 illustrates
the
anvil retention portion 16B and the cartridge retention portion 14B in an
emergency open position. If for any reason the anvil retention portion 16B and
the cartridge retention portion 14B do not move from the closed toward the
open
position under the bias of torsion spring 220, the positive opening cam
portion
227 may be used to positively cam the anvil retention portion 16B and the
1o cartridge retention portion 14B toward the open position. To use the
positive
opening cam portion 227, the surgeon merely moves the lever lock 28B from the
position in Figure 7 toward the position in Figure 6.
While the staplers 10 and 200 comprise staplers for use in a
laparoscopic surgical procedures, it should be noted that many of the features
and
devices disclosed herein may be used in a stapler designed for use in an open
surgical procedure. Figures 39 and 40 illustrate a stapler 300 for use in an
open
surgical procedure.
The stapler 300 may be substantially identical to the stapler 10, except chat
the relatively long housing portion 17 is replaced by a very short portion and
2o preferably, the stapler 300 would comprise first and second separable parts
(not
shown) which is typical for surgical staplers used in open surgical
procedures.
Like the stapler 10, the stapler 300 includes cartridge and anvil retention
portions
14C and 16C, similar approximation means, a staple housing 1120, firing handle
94C, firing rod 90C, latch 33C and release lever 35C.
The stapler 300 optionally includes a firing assembly generally
identical to the firing assembly illustrated in Figures 1-3, 13-15 and 19-20
and
includes a firing handle 94C, firing rod 90C and the pusher assembly generally
identical to the pusher assembly shown in Figures 13-I S which include pushers
118 with linear cam surfaces 1-3. The stapler 300 may optionally place staples
in
3o any of the patterns illustrated in Figures 17 and 34-36. Additionally, the
stapler
300 may also include the trapping means illustrated in Figures 21-27 and 28-
33.
The materials used to construct the staplers according to the
present invention may comprise any materials suitable for use in surgical
devices.
CA 02185154 2005-10-14
Such materials are widely known to those skilled in the art. Examples of
medical
grade materials include particular grades of stainless steel and plastics.
The present invention has now been described with reference to several
embodiments thereof. It will be apparent to those skilled in the art that many
changes can be made in the embodiment described without departing from the
scope of the present invention. For example, the staplers 10 and 200 may
incorporate the overload ~sei~ or and lockout device as disclosed in U.S.
Patent
_ No. 5,447,265 issued September 5, 1995. Additionally, either the individual
staples andJor the anvil may be coated to reduce the firing forces encountered
l0 by the surgeon. Potential coatings include Teflon, diamond like carbon and
tungsten disulfide (Dicronite). Optionally, the staples may be clad with the
same material as the anvil to reduce any potential cold welding problems.
-38-
