Surgical stapling instrument with jaw clamping mechanism

A surgical stapling instrument suitable for performing a gastrointestinal anastomosis is provided. The stapling instrument incorporates a jaw clamping mechanism which applies clamping forces to its jaw members to resist the forces exerted on the anvil and staple cartridge carrying portions of the jaw members when the staples are formed. Preferably, the stapling instrument includes a pair of elongate jaw members, one of which supports a staple cartridge adapted to receive at least two laterally spaced longitudinal rows of staples, and the other provided with an anvil adapted to form the staples. A pusher bar and knife blade assembly is slidable longitudinally relative to the jaw members to sequentially drive the staples from the cartridge and form the staples against the anvil to produce a pair of laterally spaced rows in the tissue. The pusher bar and knife blade assembly includes a knife blade for cutting the tissue along a line between the longitudinal staple rows. A latching mechanism is provided for latching the jaw members together at an intermediate position therealong adjacent to the staple cartridge and the anvil. In addition, a cam mechanism is provided for urging the jaw members apart at a position remote from the latching mechanism to resist the forces exerted on the staple cartridge and anvil when the pusher bar and knife blade assembly is actuated to staple and cut the tissue gripped between the jaw members.

FIELD OF INVENTION 
The present invention relates to a surgical stapling instrument and, more 
particularly, to a gastrointestinal anastomotic stapling instrument for 
producing one or more rows of staples which is adapted to resist the 
forces exerted on its jaw members when the staples are formed. 
Specifically, this invention relates to a linear anastomotic stapling 
instrument including a jaw clamping mechanism which applies clamping 
forces to its elongate jaw members to resist the forces exerted on the 
anvil and staple cartridge carrying portions of the jaw members when the 
staples are formed to permit uniform staple heights to be produced. 
BACKGROUND AND PRIOR ART 
In recent years, there has been an increasing tendency for surgeons to use 
stapling instruments to suture body organs and tissues such as lung, 
esophagus, stomach, duodenum and other body organs in the intestinal 
tract. The use of an appropriate stapling instrument in most instances 
performs a better job in less time and simplifies previously difficult 
surgical procedures such as gastrointestinal anastomoses. 
In the prior art, the early linear two and four row cutting staplers were 
permanent instruments into which the staples were individually hand 
loaded. These staplers were very expensive, bulky, heavy and difficult to 
load and to clean for each surgical use. An example is disclosed in U.S. 
Pat. No. 3,315,105. An improvement of the permanent type surgical stapler 
was made by providing the basic stapling instrument with a presterilized 
disposable staple loading unit and with an optional knife for dividing the 
tissue simultaneously while forming the rows of staples. An example is 
disclosed in U.S. Pat. No. 3,499,591. However, this improvement mainly 
accomplished the saving of the time previously required to load the 
staples by hand. It was still necessary for the basic instrument to be 
disassembled, cleaned, reassembled and fitted with a new cartridge and 
anvil for each surgical procedure, in addition to the maintenance required 
of the stapling instrument itself. Another problem with this type of 
instrument is the tendency for the jaws to spread apart at the distal end 
after repeated use resulting in a substantial variation in the formed 
staple heights between the proximal and distal ends of the staple rows. 
As hospital costs have continued to increase, it has become necessary to 
eliminate unnecessary work and develop more efficient techniques without 
compromise to the surgical procedure. Consequently, disposable stapling 
instruments of the type disclosed in U.S. Pat. No. 4,429,695 have been 
developed. In the disposable stapling instrument of this patent, an 
actuator and knife blade assembly provides local support to the stapler 
jaws in the region of the knife blade and pusher bar cams. However, this 
stapling instrument does not provide clamping forces simultaneously along 
the entire length of the anvil and staple cartridge carrying portions of 
the stapler jaws to resist the tendency of the jaws to separate when the 
staples are formed. Thus, there is the possibility that rows of 
non-uniform staple heights will be produced. If the tissue is stapled too 
tightly, the blood supply is compromised and the tissue may necrose. If 
stapled too loosely, the tissue may hemorrhage or, in the case of hollow 
organs such as intestine, may also leak. Thus, both too tightly and too 
loosely formed staples can cause serious problems and complications. 
Typically, a linear anastomotic stapling instrument includes a pair of 
cooperating elongate jaw members, each adapted to be inserted into 
internal, tubular body organs to be anastomosed. One of the jaw members 
supports a staple cartridge with at least two laterally spaced rows of 
staples, and the other jaw member supports an anvil with staple-forming 
pockets aligned with the rows of staples in the cartridge. Generally, a 
single pusher bar and knife assembly is slidable longitudinally along the 
jaw members to sequentially eject staples from the cartridge via camming 
surfaces which activate a plurality of staple drivers carried by the 
cartridge and associated with the individual staples to close the staples 
against the anvil and form laterally spaced rows of staples in the tissue 
gripped between the jaw members. A knife blade which trails the pusher 
bars cuts the tissue along a line between the staple rows. Examples of 
such anastomotic stapling instruments are disclosed in U.S. Pat. Nos. 
3,499,591 and 4,429,695. In neither instance is any provision made for 
application of clamping forces simultaneously along the entire portions of 
the jaw members which support the anvil and staple cartridge to resist the 
forces exerted when the staples are formed. 
In the use of stapling instruments of the above type, relatively large 
forces are exerted in clamping the tissue to be fastened between the jaw 
members, ejecting the staples from the staple cartridge, driving the 
staples into the gripped tissue, and forming the staples against the 
anvil. Such forces tend to separate the jaw members vertically and to 
distort the jaw members laterally, with the result that the consistency of 
the formed staple height is diminished, or that the staples may sometimes 
miss the anvil completely. This problem is accentuated in the case of a 
disposable stapling instrument in which relatively lightweight disposable 
materials are used for the manufacture of the jaw members and other 
components. Thus, there is a need for a disposable stapling instrument 
which is capable of accurate alignment of the jaw members while the staple 
forming operation is performed, and which provides adequate support for 
its elongate jaw members to withstand the large forces encountered in the 
operation of the stapling instrument. In addition, there is a need for a 
stapling instrument which produces staple rows of uniform height in the 
tissue gripped between its jaw members. 
SUMMARY OF INVENTION 
The present invention achieves a surgical stapling instrument which 
overcomes the disadvantages of the prior art by incorporating an improved 
jaw clamping mechanism which applies clamping forces to its jaw members to 
resist the forces exerted on the anvil and staple cartridge carrying 
portions of the jaw members during the formation of the staples. 
Preferably, the stapling instrument includes a latching mechanism for 
latching the jaw members together at an intermediate position therealong 
adjacent to the staple and anvil carrying portions of the jaw members. The 
stapling instrument also includes a cam mechanism for urging the jaw 
members apart at a position remote from the latching mechanism to resist 
the forces exerted on the anvil and staple carrying portions of the jaw 
members when the staples are formed. 
In accordance with the invention, a surgical stapling instrument comprises 
first and second cooperating elongate jaw members, one of the jaw members 
including stapling carrying means adapted to receive a plurality of 
staples arranged in at least one row, and the other jaw member including 
anvil means adapted to form the staples, pusher means for driving the 
staples from the staple carrying means into tissue gripped between the jaw 
members and forming the staples against the anvil means to produce at 
least one row of staples in the tissue, knife means for cutting the tissue 
gripped between the jaw members along a line adjacent to the row of 
staples, and jaw clamping means for applying clamping forces to the jaw 
members to resist the forces exerted on the staple carrying means and 
anvil means when the staples are formed. Preferably, the jaw clamping 
means is adapted to apply clamping forces to the jaw members which urge 
the staple carrying means and anvil means together during the formation of 
the staples against the anvil means to produce a uniform staple height. 
In a preferred embodiment, the jaw clamping means includes means for 
latching the jaw members together at an intermediate position therealong 
adjacent to the staple carrying means and the anvil means, and means for 
urging the jaw members apart at a position remote from the latching means 
to resist the forces exerted on the staple carrying means and the anvil 
means when the staples are formed. Preferably, the means for urging the 
jaw members apart comprises cam means mounted on one of the jaw members 
and engageable with the other jaw member for moving the jaw members apart 
to urge the staple carrying means and the anvil means together. The cam 
means comprises a cam member pivotally mounted on one of the jaw members 
at a position remote from the latching means. The cam member is pivotable 
from a first inoperative position to a second operative position to move 
the jaw members apart at the remote position. The cam member includes a 
first lower cam surface for engaging the other jaw member with the cam 
member disposed in its second operative position. At least one of the jaw 
members is flexible to permit portions of the jaw members to bend apart at 
the remote position. When the cam member pivots from its inoperative 
position to its operative position, the portions of the jaw members at the 
remote position bend apart to urge the anvil and staple carrying portions 
of the jaw members together. 
Preferably, the cam means is operable by the pusher means prior to the 
formation of the staples to urge the staple carrying means and anvil means 
together. Actuator means is provided for initially actuating the pusher 
means while the knife means remains stationary to actuate the cam means 
and for subsequently actuating the pusher means and the knife means 
simultaneously to drive the staples into the tissue and to cut the tissue. 
As a result, the initial force required to operate the stapling instrument 
is minimized. In addition, spacer means is mounted on one of the jaw 
members for maintaining a predetermined gap between the staple carrying 
means and the anvil means to produce a uniform staple height when the 
staples are formed. 
The present invention is embodied in a linear gastrointestinal stapling 
instrument provided with first and second elongate jaw members for 
gripping tissue therebetween. A staple cartridge carrying at least two 
laterally spaced longitudinal rows of staples is mounted on a front 
portion of one of the jaw members, and a staple forming anvil is provided 
on a front portion of the other jaw member. A pusher bar and knife blade 
assembly is slidably mounted for longitudinal movement relative to the jaw 
members. The pusher bar and knife blade assembly includes pusher means for 
driving the staples from the staple cartridge into tissue gripped between 
the jaw members and forming the staples against the anvil to produce a 
pair of laterally spaced staple rows in the tissue, and knife means for 
cutting the tissue gripped between the jaw members along a line between 
the staple rows. The stapling instrument includes jaw clamping means for 
urging the front portions of the jaw members together to clamp the staple 
cartridge and the anvil against the tissue gripped between the jaw members 
during the formation of the staples. The jaw clamping means is embodied as 
means for latching the jaw members together at an intermediate position 
therealong adjacent to the staple cartridge and the anvil, and means for 
urging the rear portions of the jaw members apart at a position remote 
from the latching means to urge the front portions of the jaw members 
together to resist the forces exerted on the staple cartridge and the 
anvil when the staples are formed. 
In a preferred embodiment, a cam mechanism is mounted on one of the jaw 
members which is engageable with the other jaw member for moving the rear 
portions of the jaw members apart to urge the staple cartridge and anvil 
together. Preferably, a cam member is pivotally mounted on one of the jaw 
members at a position remote from the latching means. The cam member is 
pivotable from a first inoperative position to a second operative position 
to move the rear portions of the jaw members apart and to urge the front 
portions of the jaw members together. The cam member includes a first 
lower cam surface for engaging the other jaw member with the cam member 
disposed in its first inoperative position and a second higher cam surface 
for engaging the jaw member with the cam member disposed in its second 
operative position. Preferably, the cam member is operable by the pusher 
means to move from its inoperative position to its operative position when 
the pusher means is advanced and to return from its operative position to 
its inoperative position when the pusher means is retracted. At least one 
of the jaw members is flexible to permit its rear portion to bend away 
from the rear portion of the other jaw member and its front portion to 
bend toward the front portion of the other jaw member to urge the staple 
cartridge and anvil together. In addition, spacer means is mounted on one 
of the jaw members for maintaining a predetermined gap between the staple 
cartridge and anvil. 
Preferably, the pusher bar and knife assembly includes a pusher block 
slidably mounted for longitudinal movement along one of the jaw members 
and provided with a pair of staple pusher bars adapted to slide into the 
staple cartridge, and a knife block slidably mounted for longitudinal 
movement along one of the jaw members and provided with a knife blade 
adapted to slide into the staple cartridge between the staple pusher bars. 
The cam mechanism is operable by the pusher block prior to the formation 
of the staples to urge the staple cartridge and anvil together. Actuator 
means is provided for initially advancing the pusher block toward the 
staple cartridge while the knife block remains stationary to actuate the 
cam mechanism and to initially move the pusher bars into the staple 
cartridge and for subsequently advancing the knife block toward the staple 
cartridge upon engagement by the pusher block to move the pusher bars and 
knife blade simultaneously into the staple cartridge. In the preferred 
embodiment, the cam mechanism is actuated by the pusher block prior to 
engagement of the pusher block with the knife block to reduce the force 
initially required to operate the stapling instrument. Preferably, the 
knife block is adapted to slidably receive the pusher bars to permit the 
pusher block to initially slide relative to the knife block when the 
pusher block is advanced to actuate the cam mechanism and when the pusher 
block is retracted after the staples are formed. The pusher bars are 
adapted to engage the knife block as the pusher block is retracted to 
withdraw the knife blade from the staple cartridge. 
The invention provides an improved linear gastrointestinal anastomotic 
stapling instrument which advantageously incorporates a cam mechanism for 
urging the staple cartridge and anvil together during the formation of the 
staples. These additional clamping forces resist the forces exerted on the 
staple cartridge and anvil when the staples are formed which would 
otherwise tend to spread the staple cartridge and anvil apart and result 
in the forming of closed staples of non-uniform height. In addition, the 
actuation of the cam mechanism by a two-stage pusher bar and knife blade 
assembly minimizes the initial force required to actuate the stapling 
instrument.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 2, the present invention is embodied in a linear 
anastomotic stapling instrument, generally 20, comprising an upper 
elongated anvil carrying jaw member 22 and a lower elongated staple 
cartridge carrying jaw member 24. Upper anvil carrying jaw member 22 is 
supported by a handle 26 with a front portion of the jaw member extending 
forwardly therefrom. Lower staple cartridge carrying jaw member 24 is 
supported by a handle 28 with a front portion of the jaw member extending 
forwardly therefrom. As shown in FIG. 3, upper handle 26 and lower handle 
28 are suitably shaped to form a hand grip to facilitate the handling and 
operation of the stapling instrument by a surgeon. An enlarged front 
protrusion 27 and a small rear protrusion 29 are provided on each handle 
for this purpose. Preferably, handles 26 and 28 are made of plastic of 
other lightweight material, while jaw members 22 and 24 are made of 
stainless steel or other similar material. 
As shown in FIG. 5, upper jaw member 22 comprises a one-piece elongated 
channel-shaped frame including a pair of opposed, elongated side walls 30 
connected by a top wall 31. Upper handle 26 includes a pair of depending 
ears 32 located inside the upper handle adjacent to its front end. Upper 
jaw member 22 includes a slot 34 (FIG. 4) formed at an intermediate 
position along its top wall 31 through which depending ears 32 project 
downward. A latch pin 36 extends through circular holes formed in side 
walls 30 of upper jaw member 22 and through circular holes formed in 
depending ears 32 to pivotally connect the upper jaw member to upper 
handle 26. 
Referring to FIG. 5, the front portion of upper jaw member 22 is provided 
with a pair of elongated inwardly extending flanges 38 which define an 
anvil 40 of the stapling instrument. Flanges 38 are separated by a central 
longitudinal slot 42 which extends along the entire length of anvil 40. At 
the proximal end of central slot 42, the flanges 38 are provided with 
inwardly sloped guide surfaces 41. Each flange 38 is also provided with 
two longitudinal rows of uniformly spaced staple-forming pockets 44. 
Referring to FIGS. 4 and 5, a tapered anvil tip 46 is mounted at the front 
of anvil carrying jaw member 22 to facilitate the insertion of the jaw 
member into hollow, tubular body organs. Anvil tip 46 includes an 
elongated body 48 (FIG. 4) which is inserted through the longitudinal 
passageway above anvil 40 defined by side walls 30 and flanges 38 of the 
upper jaw member. This elongated body 48 extends between depending ears 32 
above latch pin 36 and includes an enlarged rear portion 50 located behind 
ears 32 to hold anvil tip 46 in place on upper jaw member 22. 
Referring to FIGS. 2 and 6, lower cartridge carrying jaw member 24 
comprises a one-piece elongated channel-shaped frame including a pair of 
opposed, elongated side walls 52 connected by a bottom wall 53. Along the 
rearward portion of lower jaw member 24, a pair of spaced, elongated 
upstanding side flanges 54 (FIG. 2) extend upward from its opposed side 
walls 52. As shown in FIGS. 5 and 6, the width of lower jaw member 24 
between its side flanges 54 is greater than the width of upper jaw member 
22 between its side walls 30 to permit the rear portion of the upper jaw 
member to be received between side flanges 54 of the lower jaw member when 
the stapling instrument is assembled for operation. As shown in FIG. 2, 
each side flange 54 of lower jaw member 24 includes a vertical notch 56 
located in alignment with latch pin 36 on upper jaw member 22. When upper 
jaw member 22 and lower jaw member 24 are assembled, the opposite ends of 
latch pin 36 are received in notches 56. 
As shown in FIGS. 2 and 6, lower jaw member 24 supports a staple cartridge 
60 which is adapted to receive a plurality of surgical staples 61 (FIG. 
18) arranged in at least two laterally spaced longitudinal rows. Staple 
cartridge 60 is mounted at the front portion of lower jaw member 24 
between its side walls 52. Staple cartridge 60 is divided longitudinally 
by a central, elongated slot 62 (FIG. 6) which extends from the proximal 
end of the cartridge toward its distal end. Preferably, a plurality of 
staple openings 64 formed in staple cartridge 60 is arranged in two pairs 
of laterally spaced rows, with each pair of rows disposed on opposite 
sides of central longitudinal slot 62. A plurality of surgical staples 61 
(FIG. 18) are mounted within openings 64 of cartridge 60. As shown in FIG. 
6, the staple openings 64 in adjacent rows are staggered to provide more 
effective stapling of the tissue when the instrument is operated. 
Referring to FIGS. 15 and 16, staple cartridge 60 includes a pair of 
longitudinal slots 66 located on opposite sides of elongated central slot 
62 and disposed between the staggered rows of openings 64 on each side of 
the central slot. Each longitudinal slot 66 extends from the proximal end 
of cartridge 60 towards its distal end. 
As shown in FIG. 17, a plurality of staple drivers 65 is slidably mounted 
in staple openings 64 for actuating the staples 61 which are loaded into 
staple cartridge 60. Referring to FIG. 6, each staple driver 65 is 
designed to simultaneously actuate two staples 61 located in the adjacent 
rows provided in staple cartridge 60. Thus, a first set of staple drivers 
65 is provided for actuating the staples 61 in the staggered rows located 
on one side of central longitudinal slot 62, and a second set of staple 
drivers 65 is provided for actuating the staples 61 in the pair of 
adjacent rows located on the other side of central longitudinal slot 62. 
As shown in FIGS. 2 and 3, the front or distal end of staple cartridge 60 
includes a tapered tip 68 to facilitate the insertion of lower jaw member 
24 into a hollow, tubular body organ. Immediately behind its tapered tip 
68, staple cartridge 60 is provided with a pair of rearwardly extending 
protrusions 70 (one shown in FIG. 14) which are received in corresponding 
notches provided in side walls 52 of lower jaw member 24. At the rear of 
staple cartridge 60, a pair of depending arms 72 extends downwardly from 
the cartridge. Each arm 72 is notched to provide a side opening 74. When 
cartridge 60 is assembled on lower jaw member 24, its protrusions 70 are 
received in corresponding notches provided at the front ends of side walls 
52 and its depending arms 72 extend downwardly through an opening 76 (FIG. 
4) formed in bottom wall 53 of jaw member 24. Lower jaw member 24 includes 
a pair of depending ears 78 (FIG. 19) extending downwardly from its side 
walls 52 on opposite sides of opening 76. A pivot pin 80 extends through 
holes formed in depending ears 78 of lower jaw member 24 and through side 
openings 74 of depending arms 72 on staple cartridge 60 to fasten the 
staple cartridge to the lower jaw member. 
Referring to FIG. 2, the stapling instrument 20 includes a latching 
mechanism, generally 90, for latching upper jaw member 22 and lower jaw 
member 24 together at an intermediate position along the jaw members. 
Preferably, jaw members 22 and 24 are latched together at a position 
adjacent to the proximal ends of anvil 40 and staple cartridge 60. In the 
preferred embodiment, latching mechanism 90 comprises a latch arm 92 (FIG. 
2) pivotally connected to lower jaw member 24 via pivot pin 80 (FIG. 4). 
Latch arm 92 is channel-shaped in configuration and includes a pair of 
opposed, elongated side walls 94 (FIG. 6) which are spaced apart by a 
distance sufficient to span side walls 52 of lower jaw member 24. Each 
side wall 94 of latch arm 92 includes an upwardly and forwardly extending 
hook member 96 provided with a forwardly facing slot 98 for receiving 
latch pin 36. A shroud 100 is mounted on the lower surface of latch arm 
92. When latch arm 92 is closed, as shown in FIG. 3, shroud 100 is aligned 
with the bottom of lower handle 28 to facilitate the handling and 
operation of stapling instrument 20 by the surgeon. Preferably, shroud 100 
is made of plastic or other lightweight material, while latch arm 92 is 
made of stainless steel. As shown in FIG. 7, shroud 100 includes elongated 
flanges 102 and 104 extending outwardly from its opposite sides which 
serve as fingergrips to enable latch arm 92 to be pivoted downward from 
its latched to its unlatched position. When latch arm 92 is moved to its 
closed or latched position, the surfaces of slots 98 of hook members 96 
cooperate with latch pin 36, acting as an over-center latch to maintain 
latch arm 92 in its latched position. 
Referring to FIGS. 6 and 10, the preferred embodiment of stapling 
instrument 20 includes an improved pusher bar and knife blade assembly, 
generally 110, which is slidably mounted for longitudinal movement 
relative to upper and lower jaw members 22 and 24, respectively, for 
driving staples 61 from staple cartridge 60 into tissue gripped between 
the jaw members, forming staples 61 against anvil 40, and cutting the 
tissue along a line between the rows of staples formed in the tissue. 
Pusher bar and knife blade assembly 110 includes a pusher block 112 (FIG. 
6) which is slidably received within the lower channel-shaped jaw member 
24 between its upstanding side flanges 54. As shown in FIG. 11, pusher 
block 112 is attached to an actuator knob 114 by a flange 116 which 
includes a laterally projecting finger 118 provided with a longitudinally 
extending notch 119 on its top surface. Finger 118 is snap-fitted into a 
lateral slot 120 formed in pusher block 112 to locate notch 119 underneath 
a longitudinal locking bar 121 to secure pusher block 112 and actuator 
knob 114 together. Flange 116 of actuator knob 114 extends through and 
rides along an elongated slot 122 (FIG. 2) formed in one side flange 54 of 
lower jaw member 24. 
The pusher bar and knife blade assembly 110 includes a pair of staple 
pusher bars 124 (FIG. 10) projecting forwardly from pusher block 112 and 
slidably received in elongated slots 66 (FIG. 16) of staple cartridge 60. 
Pusher block 112 is provided with a pair of vertical slots 126 (FIG. 11) 
in which pusher bars 124 are secured. As shown in FIG. 10, the front end 
of each staple pusher bar 124 is provided with a wedge-shaped tip 128 
which defines an inclined cam surface 130 for engaging staple drivers 65 
as pusher bars 124 are advanced into staple cartridge 60. As shown in FIG. 
21, each staple driver 65 is provided with a sloped surface 132 oriented 
at the same angle as cam surface 130 of each staple pusher bar 124 to 
provide a flat, sliding contact between the surfaces. 
Referring to FIGS. 6 and 10, the pusher bar and knife blade assembly 110 
includes a knife block 134 which is slidably mounted for longitudinal 
movement along lower jaw member 24 between its upstanding side flanges 54. 
Knife block 134 includes a knife support bar 136 which extends forwardly 
into central longitudinal slot 62 of staple cartridge 60. An inclined 
knife blade 138 provided with a beveled cutting edge 140 is located at the 
front end of knife support bar 136. The beveled cutting edge of knife 
blade 138 is oriented at an angle relative to elongate jaw members 22 and 
24 and is slidably received in central longitudinal slot 62 of staple 
cartridge 60. 
In the preferred embodiment of stapling instrument 20, knife block 134 
includes a pair of longitudinal slots 135 (FIG. 20) extending therethrough 
which slidably receive staple pusher bars 124 to permit pusher block 112 
to slide relative to the knife block. Accordingly, when pusher block 112 
is advanced toward staple cartridge 60 by actuator knob 114, staple pusher 
bars 124 slide through knife block 134 which remains stationary until the 
pusher block moves into engagement with the knife block. After knife block 
134 is engaged by pusher block 112, the knife block and pusher block 
advance simultaneously toward staple cartridge 60. As shown in FIG. 18, 
knife blade 138 is advanced through staple cartridge 60 along with staple 
pusher bars 124, forming staples 61 in the tissue gripped between the jaw 
members and cutting the tissue between the staple rows. Thereafter, when 
actuator knob 114 is retracted, pusher block 112 initially slides staple 
pusher bars 124 backward through knife block 134 which remains stationary. 
Each staple pusher bar 124 includes an offset portion 142 which moves into 
engagement with knife block 134 after staple pusher bars 124 are withdrawn 
by a predetermined distance. With offset portions 142 of staple pusher 
bars 124 engaging knife block 134, pusher block 112 and knife block 134 
are simultaneously retracted by actuator knob 114 to return pusher bars 
124 and knife blade 138 to the start position. 
In accordance with the invention, stapling instrument 20 is provided with 
jaw clamping means for applying clamping forces to the jaw members to urge 
staple cartridge 60 and anvil 40 together during the formation of staples 
61. The jaw clamping means includes means for urging the jaw members apart 
at a position remote from the latching mechanism to resist the forces 
exerted on staple cartridge 60 and anvil 40 when staples 61 are formed. In 
the preferred embodiment, a cam means is mounted on one of the jaw members 
and engageable with the other jaw member for moving said jaw members apart 
at the remote position to urge staple cartridge 60 and anvil 40 together. 
Preferably, a cam member is pivotally mounted on one of the jaw members at 
a position remote from the latching mechanism. The cam member is pivotable 
from a first inoperative position to a second operative position to move 
the remote ends of the jaw members apart. The cam member is operable by 
pusher block 112 of pusher bar and knife blade assembly 110 to move to its 
operative position when the pusher block is advanced and to return to its 
inoperative position when the pusher block is retracted. 
In the preferred embodiment of the stapling instrument 20, a cam mechanism, 
generally 150, is located adjacent to the rear end of lower jaw member 24, 
as shown in FIG. 4. Cam mechanism 150 includes a cam member 152 pivotally 
mounted on a transverse pivot pin 154 extending between upstanding side 
flanges 54 of lower jaw member 24. Cam member 152 includes a first lower 
cam surface 156 for engaging top wall 31 of upper jaw member 22 with cam 
152 in its first inoperative position (FIG. 12) and a second higher cam 
surface 158 for engaging the top wall 31 of upper jaw member 22 with cam 
152 disposed in its second operative position (FIG. 13). First cam surface 
156 is arranged to maintain upper and lower jaw members substantially 
parallel with cam 152 in its inoperative position. Second cam surface 158 
is arranged to raise the rear end of upper jaw member 22 by approximately 
0.125 inch (3.2 mm) when cam 152 pivots from its inoperative position to 
its operative position. In addition, upper jaw member 22 is sufficiently 
flexible to permit the rear portion of upper jaw member 22 to bend upward 
away from lower jaw member 24 when cam member 152 is moved from its 
inoperative position to its operative position. 
As shown in FIG. 4, cam member 152 includes a radially extending notch 160 
which divides the cam into a large front finger 162 and a small rear 
finger 164. Front cam finger 162 includes a flat, rearwardly facing 
surface 165, and rear cam finger 164 includes a sloped, forwardly facing 
surface 166. With cam 152 in its inoperative position, front cam finger 
162 and rear cam finger 164 extend downwardly through an elongated slot 
168 formed in bottom wall 53 of lower jaw member 24. 
In the preferred embodiment, cam member 152 is operable by pusher block 112 
to move from its inoperative position to its operative position when the 
pusher block is advanced. As shown in FIG. 11, pusher block 112 includes a 
pair of rearwardly extending arms 170 which are spaced apart to define a 
gap 172 therebetween. The rear ends of arms 170 are connected by a cam 
actuator pin 174 which extends across gap 172. Referring to FIGS. 4 and 
11, with cam member 152 disposed in its inoperative position, front cam 
finger 162 extends through gap 172 between arms 170 of pusher block 112, 
while cam actuator pin 174 is received in notch 160 between front finger 
162 and rear finger 164 of the cam member. 
As shown in FIG. 12, with cam member 152 disposed in its first inoperative 
position, top wall 31 of upper jaw member 22 rests on first cam surface 
156 of the cam member. With cam member 152 in its inoperative position, 
top wall 31 of upper jaw member 22 is substantially parallel to bottom 
wall 53 of lower jaw member 24. In addition, pusher block 112 is located 
in its start position spaced rearwardly from knife block 134. When pusher 
block 112 is advanced, as indicated by arrow 182 (FIG. 13), cam actuator 
pin 174 engages rear surface 165 of front cam finger 162 to rotate cam 
member 152 in a counter-clockwise direction, as indicated by arrow 184, to 
pivot the cam member to its second operative position and move its second 
cam surface 158 into engagement with top wall 31 of upper jaw member 22. 
With cam member 152 pivoted to its operative position, the top wall 31 of 
upper jaw member 22 is bent upwardly, as indicated by arrow 186, away from 
bottom wall 53 of lower jaw member 24. The cam member applies forces to 
upper jaw member 22 and lower jaw member 24 which bend the rear portions 
of the jaw members apart. As a result of the bending the rear portions of 
upper jaw member 22 and lower jaw member 24 apart, additional clamping 
forces are applied to the front portions of upper jaw member 22 and lower 
jaw member 24 to clamp anvil 40 and staple cartridge 60 against the tissue 
gripped between the jaw members. Thus, anvil 40 and staple cartridge 60 
are urged together to resist the forces exerted on the anvil and staple 
cartridge when pusher bar and knife blade assembly 110 is advanced to form 
staples 61 and cut the tissue. 
Referring to FIG. 13, when pusher block 112 is retracted after staples 61 
are formed, cam actuator pin 174 engages sloped surface 166 of rear cam 
finger 164 to pivot cam member 152 in a clockwise direction. As cam 
actuator pin 174 moves along sloped surface 166 into notch 160, cam member 
152 pivots in a clockwise direction and returns to its first inoperative 
position (FIG. 12) with its first cam surface 156 in engagement with top 
wall 31 of upper jaw member 22. As a result, the forces exerted on the 
rear portions of upper jaw member 22 and lower jaw member 24 by cam 152 
are released and top wall 31 of upper jaw member 22 returns to a 
substantially parallel relationship with bottom wall 53 of lower jaw 
member 24. Similarly, the clamping forces applied to the front portions of 
jaw members 22 and 24 are released to unclamp anvil 40 and staple 
cartridge 60. 
The preferred embodiment of stapling instrument 20 includes spacer means 
mounted on one of the jaw members for maintaining a predetermined gap 
between staple cartridge 60 and anvil 40 of the stapling instrument. 
Referring to FIGS. 4 and 6, this spacer means is embodied as a spacer pin 
190 mounted adjacent to the distal end of staple cartridge 60. Spacer pin 
190 extends vertically upward from bottom wall 53 of lower jaw member 24 
through staple cartridge 60 and projects upwardly from the top of the 
staple cartridge by a predetermined distance. As shown in FIG. 5, one 
flange 38 of anvil 40 includes a flange section 192 adjacent to its distal 
end for engaging spacer pin 190. With the stapling instrument assembled 
for operation (FIG. 4), spacer pin 190 engages flange section 192 to 
maintain a predetermined gap between anvil 40 and staple cartridge 60. 
In the operation of stapling instrument 20, the tissue to be stapled and 
cut must be initially placed between jaw members 22 and 24 and clamped by 
the jaw members. Thus, handles 26 and 28 are unlatched by pivotal movement 
of latch arm 92 downward to its unlatched position (FIG. 2). As a result, 
the opposite ends of latch pin 36 are disengaged from slots 98 formed in 
hook members 96 of latching arm 92. Thereafter, upper and lower jaw 
members 22 and 24 can be separated by disengaging latch pin 36 from slots 
56 formed in side flanges 54 of the lower jaw member. 
Next, the tissue to be stapled and cut is placed on jaw members 22 and 24. 
For example, as shown in FIG. 17, a piece of tubular, intestinal tissue 
may be slipped onto the front portion of each jaw member. After the tissue 
is placed on the jaw member, stapling instrument 20 is reassembled. The 
reassembly can be accomplished by aligning latch pin 36 with vertical 
slots 56 formed in upstanding side flanges 54 of lower jaw member 24. 
Thereafter, side flanges 54 of lower jaw member 24 are positioned inside 
upper handle 26, spanning side walls 30 of upper jaw member 22, while the 
opposite ends of latch pin 36 are inserted into vertical slots 56. 
Finally, latch arm 92 is pivoted upward to its latched position (FIG. 3) 
with its cover 100 flush with the bottom of lower handle 28. As a result, 
hook members 92 are pivoted over latch pin 36 and slots 98 receive the 
opposite ends of the latch pin. Thus, upper jaw member 22 and lower jaw 
member 24 are latched together at an intermediate position therealong 
adjacent to anvil 40 and staple cartridge 60. In addition, spacer pin 190 
engages flange section 192 of anvil 40 through the body tissue to maintain 
a predetermined gap between anvil 40 and staple cartridge 60. 
After the tissue is clamped between the jaw members, stapling instrument 20 
is fired by advancing actuator knob 114 to actuate the pusher bar and 
knife blade assembly 110. Initially, in the actuation of cam mechanism 
150, pusher block 112 and pusher bars 124 (FIG. 4) are advanced, while 
knife block 134 remains stationary. Since only pusher block 112 and its 
pusher bars 124 are advanced to actuate cam member 152, the initial force 
required to operate stapling instrument 20 is minimized. 
Referring to FIG. 12, during the initial advance of pusher block 112, 
pusher bars 124 slide through knife block 134 and the wedge-shaped tips 
128 of the pusher bars begin to advance through slots 66 of staple 
cartridge 60. As pusher block 112 advances toward knife block 134, its cam 
actuator pin 174 engages rear surface 165 of front cam finger 162 to pivot 
cam 152 counter-clockwise, as indicated by arrow 184 of FIG. 13, to move 
the second cam surface 158 of the cam member into engagement with top wall 
31 of upper jaw member 22. Cam member 152 applies forces to upper jaw 
member 22 and lower jaw member 24 which bend the rear portions of the jaw 
members apart. As a result, the rear end of top wall 31 of upper jaw 
member 22 is bent upward by approximately 0.125 inch (3.2 mm) relative to 
the rear end of bottom wall 53 of lower jaw member 24. The bending of the 
rear ends of jaw members 22 and 24 apart results in additional clamping 
forces on the front portions of the jaw members to clamp anvil 40 and 
staple cartridge 60 against the tissue gripped between the jaw members. 
These additional clamping forces tend to resist the forces exerted on 
anvil 40 and staple cartridge 60, while the tissue is cut and staples 61 
are formed against anvil 40, to maintain the desired spacing between anvil 
40 and staple cartridge 60 to produce formed staples 61 which are 
substantially uniform in height. 
Referring to FIG. 13, after cam mechanism 150 is actuated, pusher block 112 
subsequently engages knife block 134 to begin the longitudinal movement of 
knife block 134 toward staple cartridge 60. Preferably, the initial 
spacing between pusher block 112 and knife block 134 is arranged such that 
pusher block 112 engages knife block 134 slightly before cam member 152 
arrives at its operative position. Alternatively, the initial spacing 
between pusher block 112 and knife block 134 can be arranged such that 
pusher block 112 initially engages knife block 134 after the movement of 
cam member 152 to its operative position is completed. When pusher block 
112 engages knife block 134, the advance of knife blade 138 along central 
longitudinal slots 42 and 62 of anvil 40 and staple cartridge 60, 
respectively, is initiated. Thereafter, staple pusher bars 124 and knife 
blade 138 are advanced simultaneously to staple and cut the tissue gripped 
between anvil 40 and staple cartridge 60. 
As pusher block 112 is advanced, staple pusher bars 124 are moved 
longitudinally along slots 66 provided in staple cartridge 60. The two 
wedge-like cam surfaces 130 of staple pusher bars 124 move through slots 
66 into engagement with the sloped surfaces of staple drivers 65 to 
sequentially drive staples 61 from cartridge 60 and to form staples 61 
into B-shaped configuration against anvil flanges 38. The cam surfaces 130 
are located at the same distance from pusher block 112 to simultaneously 
actuate staple drivers 65 located on opposite sides of central 
longitudinal slot 62. At the same time, knife block 134 is advanced to 
move knife blade 138 through central longitudinal slot 42 of anvil 40 and 
through central longitudinal slot 62 of staple cartridge 60 to cut the 
tissue gripped between the jaw members. The additional clamping forces 
applied to the front portions of upper jaw member 22 and lower jaw member 
24 via cam mechanism 150 tend to resist the forces exerted on anvil 40 and 
staple cartridge 60 when staples 61 are formed. 
After pusher block 112 is fully advanced to form all of the staples in 
cartridge 60, the pusher block is retracted toward its start position by 
retraction of actuator knob 114. Initially, only pusher block 112 moves 
backward from staple cartridge 60 because staple pusher bars 124 slide 
through knife block 134 which remains stationary. When offset portions 142 
of staple pusher bars 124 engage the front of knife block 134, the knife 
block is moved backward from staple cartridge 60 along with pusher block 
112. As a result, staple pusher bars 124 and knife blade 138 are 
simultaneously retracted from staple cartridge 60 and anvil 40. 
As pusher block 112 returns toward its start position, cam actuator pin 174 
engages sloped surface 166 of rear cam finger 164 to pivot cam member 152 
in a clockwise direction toward its inoperative position. Cam actuator pin 
174 moves along sloped surface 166 into slot 160 between cam fingers 162 
and 164 to return cam member 152 to its inoperative position. As a result, 
second cam surface 158 of cam member 152 is disengaged from the top wall 
of upper jaw member 22 and rear end of top wall 31 of upper jaw member 22 
moves downward into engagement with first cam surface 156. At the same 
time, front cam finger 162 pivots downward into gap 172 between fingers 
170 on pusher block 112, and both cam fingers 162 and 164 pivot downward 
into slot 168 formed in bottom wall 53 of lower jaw member 24. Thereafter, 
with cam member 152 in its inoperative position, latching arm 92 can be 
pivoted downward, as shown in FIG. 2, to permit upper jaw member 22 and 
lower jaw member 24 to be disassembled. At this point, the cut and stapled 
tissue can be removed from the jaw members. 
The invention in its broader aspects is not limited to the specific details 
shown and described, and modifications may be made in the structure of the 
linear anastomosis stapling instrument disclosed without departing from 
the principles of the present invention.