U.S. patent number RE39,841 [Application Number 11/499,818] was granted by the patent office on 2007-09-18 for surgical stapling instrument.
This patent grant is currently assigned to Ethicon Endo-Surgery, Inc.. Invention is credited to Federico Bilotti, Laszlo Csiky, Mark A. Neurohr, Todd P. Omaits.
United States Patent |
RE39,841 |
Bilotti , et al. |
September 18, 2007 |
Surgical stapling instrument
Abstract
A surgical stapling instrument comprises a frame having a body
portion and a handle. A staple fastening assembly is provided in
the distal region of the instrument and includes a cartridge
device, which comprises at least one closed row (10, 12) of
staples, and an anvil. The anvil is movable relative to the
cartridge device and is adapted to cooperate with the cartridge
device for forming the ends of the staples exiting from the
cartridge device. A knife, which has a closed cutting edge, is
contained within the cartridge device and is positioned such that
there is at least one closed row (10, 12) of staples on the outside
of the cutting edge. It can be moved towards the anvil. The line
along which the closed row (10, 12) of staples is arranged has a
stepped shape, leaving a plane perpendicular to the longitudinal
axis of the staple fastening assembly, such that this line has a
larger total length than the projection of this line onto this
plane. This provides a greater flexibility of the anastomotic site
and less tension during instrument removal, alleviating the
incidence of clinical complications.
Inventors: |
Bilotti; Federico (LT,
IT), Neurohr; Mark A. (Newport, KY), Csiky;
Laszlo (Huszar u.6., HU), Omaits; Todd P.
(Liberty Township, OH) |
Assignee: |
Ethicon Endo-Surgery, Inc.
(Cincinnati, OH)
|
Family
ID: |
7707186 |
Appl.
No.: |
11/499,818 |
Filed: |
August 7, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
10287067 |
Nov 4, 2002 |
06978922 |
Dec 27, 2005 |
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Foreign Application Priority Data
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Nov 28, 2001 [DE] |
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101 58 246 |
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Current U.S.
Class: |
227/180.1;
227/176.1; 227/181.1; 227/19 |
Current CPC
Class: |
A61B
17/115 (20130101); A61B 17/1155 (20130101); A61B
17/32 (20130101); A61B 2017/07264 (20130101) |
Current International
Class: |
A61B
17/04 (20060101); A61B 17/10 (20060101) |
Field of
Search: |
;227/181.1,19,180.1,175.1,176.1,177.1,179.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1090592 |
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Apr 2001 |
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EP |
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122539 |
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Jul 1984 |
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RU |
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WO 01/54594 |
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Jan 2000 |
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WO |
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Primary Examiner: Nash; Brian
Attorney, Agent or Firm: Welsh & Flaxman LLC
Claims
What is claimed is:
1. A surgical stapling instrument having a distal end, a proximal
end, and a longitudinal axis therebetween, said instrument
comprising: a flame having a body portion and a handle, a staple
fastening assembly (1) in the distal region of said instrument, the
staple fastening assembly (1) including a cartridge device (2),
said cartridge having a distal surface having a stepped
configuration comprising a series of alternating gaps and
protrusions such that said protrusions are distal to said gaps,
said cartridge device further comprising at least one closed row
(10, 12) of staples disposed along said series of alternating gaps
and protrusions, and an anvil (4) which is movable relative to the
cartridge device (2) and is adapted to cooperate with the cartridge
device (2) for forming the ends of the staples exiting from the
cartridge device (2), a moving device adapted to move the anvil (4)
relative to the cartridge device (2), a staple driving device
adapted to drive the staples out of the cartridge device (2)
towards the anvil (4), a knife, which has a closed cutting edge, is
contained within the cartridge device (2) and is positioned such
that there is at least one closed row (10, 12) of staples on the
outside of the cutting edge, and a knife actuating device adapted
to move the knife towards the anvil (4).
2. Stapling instrument according to claim 1, characterized in that
the anvil (4) has a proximal surface having a stepped configuration
comprising a series of alternating gaps and protrusions which
matches the stepped configuration cartridge, such that said gaps on
said cartridge match said protrusions on said anvil, and said
protrusions on said cartridge match said gaps on said anvil.
3. Stapling instrument according to claim 1, characterized in that
said knife has a stepped shape which matches the stepped
configuration of said distal surface of said cartridge.
4. Stapling instrument according to claim 1, characterized in that
the staple driving device (30) is adapted to drive the staples out
of the cartridge device (2) such that each staple is moved
essentially in parallel to the longitudinal axis of the staple
fastening assembly (1).
5. Stapling instrument according to claim 4, characterized in that
the staple driving device (30) comprises pushers (36, 38, 39) for
driving the staples.
6. Stapling instrument according to claim 5, characterized by at
least two groups of pushers (38, 39) having different lengths.
7. Stapling instrument according to claim 5 or 6, characterized in
that the pushers (36, 38, 39) are integrally combined in a sleeve
structure (30).
8. Stapling instrument according to claim 1, characterized in that
the staple driving device (30) is adapted to drive the staples of a
closed row (10, 12) of staples essentially simultaneously out of
the cartridge device (2).
9. Stapling instrument according to claim 1, characterized by at
least two closed rows (10, 12) of staples, wherein the staples of
adjacent rows (10, 12) are staggered with respect to each
other.
10. Stapling instrument according to claim 1, characterized in that
the anvil (4) comprises a counterpart adapted to accommodate the
cutting edge of the knife.
11. Stapling instrument according to claim 1, characterized in that
the staple fastening assembly (1) is removably mounted in the
distal end region of the body portion.
12. Stapling instrument according to claim 1, characterized in that
the anvil (4) is removable.
13. Stapling instrument according to claim 12, characterized in
that the anvil comprises a shaft fitting onto a peg protruding from
the cartridge device, which peg preferably comprises a mandrel.
14. Stapling instrument according to claim 1, characterized in that
the cartridge device (2) comprises a removable cartridge containing
the staples.
Description
BACKGROUND OF THE INVENTION
The invention relates to a surgical stapling instrument, which can
be used for applying surgical staples or clips to tissue and in
particular for performing an anastomosis.
Generally, in the performance of a surgical anastomotic stapling
operation, two pieces of lumen or tubular tissue, e.g., intestinal
tissue, are attached together by a closed row of staples. In
performing the anastomosis with a surgical stapling instrument, the
two pieces of tubular tissue are clamped together between an anvil
provided with an array of staple forming grooves and a staple
holder or cartridge device provided with a plurality of staple
receiving slots arranged in a closed row or array in which the
staples are received. A staple pusher is advanced to drive the
staples into the tissue and form the staples against the anvil.
Moreover, a circular knife is advanced to cut the excess tissue
clamped between the anvil and the staple holder. As a result, the
donut-shaped section of tissue is severed from each lumen and
remains on the anvil shaft. The tubular tissue joined by the closed
row of staples is unclamped by moving the anvil relative to the
staple holder, usually by advancing the anvil shaft distally to
move the anvil away from the staple holder. The stapling instrument
is removed by pulling the anvil through the opening between the
pieces of tubular tissue attached by the array of staples.
Surgical stapling instruments of this kind are well-known. For
example, U.S. Pat. No. 5,205,459 describes such an instrument in
detail. As usual, the closed row of staples of the instrument
disclosed has a planar, circular shape. U.S. Pat. No. 5,275,322 is
a document showing a basic version of a circular stapling
instrument.
Although the use of the known surgical stapling instruments is very
beneficial and greatly facilitates the performance of an
anastomosis, it involves some problems. Often it is difficult to
retract the instrument from the site of the operation, because it
is difficult to move the anvil through the opening bordered by the
closed row of staples, which is somewhat stiff. Moreover, after the
operation, the incidence of clinical stenosis at the site of the
anastomosis is not rare.
In order to overcome these problems, it is proposed in WO 01/54594
A1 to arrange the closed row of staples in a wavy shape which
leaves a plane perpendicular to the longitudinal axis of the
instrument. In this way, the line along which the staples of the
closed row are arranged has a larger total length than the
projection of this line onto a plane. Consequently, the length of
an anastomosis seam is larger than that of an anastomosis performed
by means of conventional stapling instrument. Because of this
increased length, the anastomotic site can assume a larger diameter
and is more flexible, so that the anvil can be easily moved through
the opening created by the knife, and the surgical stapling
instrument can be retracted at the end of the surgery more easily.
Additionally, the resulting larger anastomosis lumen will alleviate
the incidence of clinical complications. On the other hand, if it
is sufficient that the total length of the closed row of staples is
comparable to that provided by a conventional stapling instrument,
this instrument can be designed in a more compact size such that it
can be easier inserted into a tubular organ and removed
therefrom.
For optimum performance of the stapling instrument disclosed in WO
01/54594 A1, the individual staples are expelled from the cartridge
device in a direction perpendicular to the local slope of the wavy
shape, which generally is not parallel to the longitudinal axis of
the instrument. This requires a more complicated staple drive
mechanism which experiences load components transverse to the
longitudinal axis of the instrument. Moreover, the alignment of the
staple-forming grooves at the anvil to the pointed ends of the
staples exiting from the cartridge device is only correct for a
certain distance between the cartridge device and the anvil, i.e.
for a certain thickness of the tissue clamped between the cartridge
device and the anvil, which results in a loss of variability with
respect to the tissue thickness.
EP 1 090 592 A1 discloses a linear surgical stapler, in which the
anvil has two staple-forming surfaces which are spaced with respect
to each other in the staple expelling direction. In this way, the
anvil is formed with a stiffening rib which generally strengthens
the cantilever design of the linear stapler.
BRIEF SUMMARY OF THE INVENTION
The object of the invention is to provide a surgical stapling
instrument for performing an anastomosis, which has the advantages
of the instrument disclosed in WO 01/54594 A1, but allows for a
simpler design and generally exhibits less restrictions with
respect to tissue thickness.
The surgical stapling instrument according to the invention
comprises a frame having a body portion and a handle as well as a
staple fastening assembly in the distal region of the instrument.
The staple fastening assembly includes a cartridge device which
comprises at least one closed row of staples, and an anvil. The
anvil is movable relative to the cartridge device and is adapted to
cooperate with the cartridge device for forming the ends of the
staples exiting from the cartridge device. A moving device is
adapted to move the anvil relative to the cartridge device. A
staple driving device is adapted to drive the staples out of the
cartridge device towards the anvil. A knife, which has a closed
cutting edge, is contained within the cartridge device and is
positioned such that there is at least one closed row of staples on
the outside of the cutting edge. A knife actuating device is
adapted to move the knife towards the anvil. So far, these features
are known from the prior art, e.g., from U.S. Pat. No.
5,205,459.
According to the invention, the line along which the closed row of
staples is arranged has a stepped shape, leaving (i.e., not being
confined to) a plane perpendicular to the longitudinal axis of the
staple fastening assembly, such that said line has a larger total
length than the projection of said line onto said plane.
Preferably, this projection is circular.
Thus, the line along which the closed row of staples is arranged
has a larger total length than the line defining the planar array
of staples of a conventional prior art surgical stapling instrument
in which the cartridge device has about the same size.
Consequently, similar to the instrument disclosed in WO 01/54594
A1, the length of the anastomosis seam is larger than that of an
anastomosis performed by means of a conventional stapling
instrument. Because of this increased length, the anastomotic site
can assume a larger diameter and is more flexible, so that the
anvil can be easily removed through the opening created by the
knife, and the surgical stapling instrument can be retracted at the
end of the surgery more easily. Additionally, the resulting larger
anastomosis lumen will alleviate the incidence of clinical
complications. On the other hand, if it is sufficient that the
total length of the line along which the closed row of staples is
arranged is comparable to that provided by a conventional stapling
instrument, the invention allows for the use of a smaller
instrument, which generally can be more easily inserted into the
tubular organ and removed therefrom.
So far, the advantages of the surgical stapling instrument
according to the invention are similar to those of the instrument
disclosed in WO 01/54594 A1.
Additional advantages result from the stepped shape of the line
along which the closed row of staples is arranged. In particular,
this allows for a design in which a local flat area, which is
normal to the longitudinal axis of the instrument, is created for
each staple. By applying a simple conventional axial drive
mechanism, the staple driving device can be adapted to drive the
staples out of the cartridge device such that each staple is moved
essentially in parallel to the longitudinal axis of the staple
fastening assembly, which is the optimum direction in view of the
stepped shape of the closed row of staples. Such kind of drive
mechanism avoids undesired transverse loads. Moreover, the pointed
ends of staples exiting from the cartridge device stay aligned to
the staple-forming grooves provided at the anvil, irrespective of
the actual distance between the anvil and the cartridge device or
the thickness of the tissue clamped between the anvil and the
cartridge device. In other words, any anvil deflection or any
staple height adjustability will not adversely effect staple
location. When a simple axial drive mechanism is employed, the
stroke or actuating behaviour of conventional instruments can be
maintained, which is an advantage because surgeons are familiar
with it. Finally, the invention allows for the application of
existing circular stapler platforms, i.e. of existing components
like frame, moving device, and staple driving device, and therefore
saves considerable costs.
Preferably, the anvil has a stepped staple-forming surface which
matches the stepped shape of the line along which the closed row of
staples is arranged.
Whereas it is conceivable that the knife has a conventional
(cylindrical) basic shape with a circular cutting edge, in a
preferred version of the invention the line defining the cutting
edge of the knife has a stepped shape and runs essentially in
parallel to the line along which the closed row of staples is
arranged. In this design, the knife has to be moved by a short
distance only in order to completely cut the tissue clamped between
the cartridge device and the anvil.
In an advantageous version of the invention, the staples of a
closed row of staples are arranged at different positions, measured
along the longitudinal axis of the staple fastening assembly. In
this way, the staples are located at different steps of the stepped
shape of the closed row of staples. Alternatively, or with respect
to another closed row of staples, the staples of a closed row of
staples can be arranged with gaps between adjacent staples, wherein
each gap is defined by a recess in the surface of the cartridge
device, and the anvil has a protrusion fitting into that recess. Or
the staples can be arranged with protrusions between adjacent
staples, wherein each protrusion emerges from the surface of the
cartridge device, and the anvil has a recess for accomodating that
protrusion. A corresponding closed row of staples having both
protrusions and gaps or recesses between different pairs of
adjacent staples is conceiveable as well. Thus, the line along
which such closed rows of staples are arranged has a stepped shape,
since this line also follows the gaps or protrusions, although the
staples themselves may be located all in the same plane.
As already mentioned, in a preferred version of the invention, the
staple driving device is adapted to drive the staples out of the
cartridge device such that each staple is moved essentially in
parallel to the longitudinal axis of the staple fastening assembly.
This allows for a simple, reliable and less expensive design of the
surgical stapling instrument. Preferably, the staple driving
devices comprises pushers for driving the staples. For adjustment
to the stepped shape of the closed row of staples, the pushers can
have different lengths. In an advantageous version, the pushers are
integrally combined in a sleeve structure. Providing pushers of
different lengths allows for a simple design in which the staple
driving device is adapted to drive the staples of a closed row of
staples essentially simultaneously out of the cartridge device.
Such actuating behaviour maintains the stroke of a conventional
stapling instrument.
Preferably, there are at least two closed rows of staples, wherein
the staples of adjacent rows are staggered with respect to each
other. The staggered arrangement of the staples does not contradict
the basic idea of the stepped shape of the closed rows of staples,
which will become evident from the embodiment described below in
more detail. An anastomosis seam containing two rows of staggered
staples is tight and safe.
The anvil can comprise a counterpart adapted to accommodate the
cutting edge of the knife. The counterpart preferably matches the
stepped shape of the anvil and/or the knife. Such counterparts,
which exert a reaction force onto the tissue during the cutting
action and are cut by the knife, are generally known in the prior
art, see, e.g., U.S. Pat. No. 4,289,133.
In an advantageous version of the invention, the staple fastening
assembly is removably mounted in the distal end region of the body
portion. This enables, e.g., the staple fastening assembly to be
exchanged during the surgical operation or to be designed as a
disposable part (whereas the frame including a major part of the
mechanical components is sterilizable and reusable). Moreover, the
cartridge device can comprise a removable cartridge containing the
staples, such that, e.g., an empty cartridge can be replaced by a
fresh one, if required, or the cartridge device can be designed as
a re-usable component. Preferably, the anvil is removable as well,
which is also essential for certain surgical techniques. To this
end, the anvil can comprise a shaft fitting onto a peg protruding
from the cartridge device. The peg preferably comprises a mandrel
which is useful for piercing tissue in certain surgical techniques.
These features are generally known from the prior art surgical
stapling instruments.
The term "staple" is used herein in a very general sense. It
includes metal staples or clips, but also surgical fasteners made
of synthetic material and similar fasteners. Synthetic fasteners
usually have a counterpart (retainer member) held at the anvil. In
this sense, the term "anvil" also has a broad meaning which
includes, in the case of two-part synthetic fasteners, the
anvil-like tool where the retainer members are held, and similar
devices.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, the invention is described in more detail by
means of an embodiment. The drawings show in
FIG. 1 a side view of the staple fastening assembly of an
embodiment of the surgical stapling instrument according to the
invention,
FIG. 2 an isometric view onto an end part which forms the distal
surface of the cartridge device of the staple fastening assembly of
FIG. 1,
FIG. 3 an isometric view of the distal portion of the staple
driving device of the embodiment,
FIG. 4 an isometric view onto the staple-forming surface of the
anvil of the embodiment of the stapling instrument,
FIG. 5 an isometric view onto the staple-forming surface of the
anvil of another embodiment of the stapling instrument.
FIG. 1 is a side view of the staple fastening assembly 1 which
forms the distal portion of a surgical stapling instrument. The
staple fastening assembly 1 includes a cartridge device 2 (which
comprises, in the embodiment, two closed rows of staples) and an
anvil 4. The anvil 4 is mounted at the distal end of a shaft 5 and
can be moved relative to the cartridge device 2, i.e. along the
longitudinal axis of the staple fastening assembly 1, in order to
adjust the size of the gap between the anvil 4 and the cartridge
device 2.
The cartridge device 2 comprises a housing 6 which contains the
staples, a circular knife, as well as components of a moving device
(adapted to move the anvil 4 relative to the cartridge device 2), a
staple driving device (adapted to drive the staples out of the
cartridge device 2 towards the anvil 4), and a knife actuating
device (adapted to move the knife towards the anvil 4). The end
face of the cartridge device 2, i.e. the surface from which the
staples exiting from the cartridge device 2 are expelled towards
the anvil 4, is formed in an end part 7 inserted into the
circumferential wall of the housing 6.
The staple fastening assembly 1 can be removably mounted on a shaft
of the stapling instrument by means of a coupling 8 provided at the
proximal end region of the cartridge device 2. The terms "proximal"
and "distal" relate to the view of the person operating the
stapling instrument.
Generally, the overall design and the mechanical components, drive
mechanisms and safety features of the surgical stapling instrument
are as in a conventional circular stapling instrument; the
three-dimensional shape of the staple lines and some details of the
staple driving device, however, are different, as explained in the
following.
FIG. 2 shows the end part 7 in an isometric view. The distal
surface of the end part 7 comprises slots from which the staples
are expelled towards the anvil 4 when the stapling instrument is
"fired". These slots are arranged in two closed rows, thus defining
a first closed row 10 of staples (the outer one in FIG. 2) and a
second closed row 12 of staples (the inner one in FIG. 2).
Three of these exit slots of the first closed row 10 are designated
by the reference numerals 14, 15, and 16. As shown in FIG. 2, the
exit slots 14, 15, and 16 and all the other exit slots of the first
closed row 10 lie in the same plane, i.e. a plane perpendicular to
the longitudinal axis of the staple fastening assembly 1. Between
the exit slots 14 and 15, there is a gap or recess 18, whereas a
protrusion 19 emerges from the area between the exit slots 15 and
16. This pattern is repeated along the circumference of the first
closed row 10. In this way, the line along which the first closed
row 10 of staples is arranged, i.e. the line around the first
closed row 10 following the surface topography of the end part 7
and descending into the recess 18 and ascending around the
protrusion 19, has a stepped shape. It is this line which defines,
in the area of the first closed row 10, the tissue contact between
the cartridge device 2 and the anvil 4 when the stapling instrument
is operated.
In a similar manner, the line along which the second closed row 12
of staples is arranged has a stepped shape as well. In this case,
however, the exit slots of the staples are located in two different
planes, each perpendicular to the longitudinal axis of the staple
fastening assembly 1. As shown in FIG. 2, exit slots 20 and 22 are
in the same plane which is more distal than the plane of the exit
slots of the first closed row 10. Exit slot 21, which is arranged
between the exit slots 20 and 22, is located in the other plane and
is more proximal than the exit slots of the first closed row 10.
This pattern is repeated along the circumference of the second
closed row 12. In the embodiment, the peaks of the protrusions 19
are in the plane of the exit slots 20 and 22, whereas the grounds
of the recesses 18 are in the plane of exit slot 21. Exit slot 21
and the corresponding exit slots of the second closed row 21 are
radially aligned with the recesses 18. As shown in FIG. 2, the
staples of the first closed row 10 and the staples of the second
closed row 12 are staggered with respect to each other.
In FIG. 2, a staple guide part 24 is located below the distal
surface of the end part 7. The staple guide part 24 comprises guide
slots 26 for guiding the staples of the first closed row 10 and
guide slots 28 for guiding the staples of the second closed row 12.
Each of theses guide slots 26, 28 accommodates one staple, the
pointed ends of the staple facing the corresponding exit slot. The
staple guide part 24 as well as the end part 7 are preferably made
of a medical grade resin by injection moulding and may be
manufactured as one component.
The circular knife, which is not shown in the figures, is guided at
the inner periphery of the end part 7. It is moved in distal
direction when the stapling instrument is actuated, as usual with
conventional circular staplers. In the embodiment, the cutting edge
of the knife has a stepped shape which essentially follows the
stepped shape of the line along which the second closed row 12 of
staples is arranged.
FIG. 3 shows the distal portion 30 of the staple driving device of
the stapling instrument. In the embodiment, this portion is
designed as an integrally moulded sleeve structure. It includes an
actuator shaft 32 distally ending at a base 34 which is reinforced
by means of ribs 35. The proximal end of the actuator shaft 32 is
coupled to an actuating rod inside the shaft of the stapling
instrument when the staple fastening assembly 1 is mounted to the
distal end of this shaft. When the instrument is "fired", i.e. when
an actuating trigger located at the handle of the instrument is
operated, the actuating rod is moved in distal direction, thus
pushing the sleeve structure 30 in distal direction as well.
For each staple, the staple driving device 30 comprises a pusher
protruding in distal direction and parallel to the longitudinal
axis of the staple fastening assembly 1. These pushers are arranged
in two rows, i.e. the outer pushers 36 for the first closed row 10
of staples and the inner pushers 38 and 39 for the second closed
row 12 of staples. In the assembled state of the staple fastening
assembly 1, the pushers 36 are guided in the guide slots 26,
whereas the pushers 38 and 39 are guided in the guide slots 28. As
shown in FIG. 3, all of the pushers 36 have the same length, but
the pushers 39 are shorter than the pushers 38. The end side of
each pusher 36, 38 and 39 abuts at the crown of a staple such that
the staples are expelled from the exit slots of the first closed
row 10 and the second closed row 12 when the instrument is
fired.
The shorter pushers 39 are assigned to exit slot 21 and the
corresponding exit slots of the second closed row 12, whereas the
longer pushers 38 are assigned to the exit slots 20, 22 and the
other exit slots in the more distal plane for the second closed row
12. The length of the pushers 36 is between that of the pushers 38
and 39, corresponding to the location of the exit slots of the
first closed row 10. This design results in an almost simultaneous
exit of all staples from their exit slots when the instrument is
fired.
FIG. 4 is an isometric view onto the proximal surface of the anvil
4, which includes a peripheral rim 40 and an end plate 42. The
proximal end side of the rim 40 is designed as a staple-forming
surface 43. For each staple, the staple-forming surface 43
comprises a pair of staple-forming grooves which form or bend the
pointed ends of the staple when these ends are pushed against the
staple-forming surface 43 upon firing the instrument.
The relief of the staple-forming surface 43 is essentially a
negative of the relief of the end surface of end part 7. Thus, in
the mounted state of the anvil 4, the grooves 44, 45, and 46 match
to the exit slots 14, 15, and 16 of the first closed row 10, and a
protrusion 48 between the grooves 44 and 45 fits into the recess
18, whereas a recess 49 accommodates the protrusion 19 when the
anvil 4 is close to the cartridge device 2. Similarly, the
locations of grooves 50, 51, and 52 match to the positions of the
exit slots 20, 21, and 22 of the second closed row 12.
Generally, the stapling instrument is operated like a conventional
circular stapler. By moving the anvil 4 towards the cartridge
device 2, the tissue ends to be stapled are clamped between the end
surface of end part 7 and the staple-forming surface 43 of the
anvil 4. The tissue follows the stepped shapes of the lines along
which the first closed row 10 and the second closed row 12 of
staples are arranged and is forced by protrusions like the
protrusion 48 or the staple-forming surface 51 on the anvil 4 into
corresponding recesses like the recess 18 or the area of the exit
slot 21, and vice versa. The width of the recesses like recess 49
or recess 18 is somewhat larger than the width of the corresponding
protrusions like protrusion 19 or protrusion 48, such that the
tissue is not squeezed in the protrusion/recess pairs.
When the instrument is fired, the staples of the first closed row
10 and the second closed row 12 are expelled almost simultaneously
from the end surface of the end part 7, penetrate the tissue parts
and are formed at the staple-forming surface 43 of the anvil 4.
Immediately afterwards, the cutting edge of the circular knife,
which is mounted on the staple driving device 30 inside the pushers
38 and 39 of the second closed row 12, cuts the tissue.
After firing, the distance between the anvil 4 and the cartridge
device 2 is somewhat increased in order to release the anastomosis
seam. Because of the stepped structures of the end surface of the
end part 7 and the staple-forming surface 43 of the anvil 4, the
staple lines of the anastomosis seam have a greater length than
comparable staple lines resulting from corresponding smooth
surfaces in a conventional circular stapler of the same outer
diameter. Consequently, retraction of the instrument is easier.
FIG. 5 is an isometric view onto the proximal surface of the anvil
4' of a second embodiment of the surgical stapling instrument. The
anvil 4' is the counterpart of a cartridge device having two closed
raws of staples, in which the designs of the outer closed raw of
staples and of the inner closed raw of staples are reversed with
respect to the cartridge device 2 of the first embodiment. To
facilitate comparison with FIG. 4, in FIG. 5 the same reference
numerals are used as in FIG. 4, but they are primed.
The relief of the staple-forming surface 43' is essentially a
negative of the relief of the end surface of the cartridge device
of the second embodiment. In a corresponding staple driving device,
the lengths of the pushers are adjusted to the locations of the
staples in the cartridge device of the second embodiment. The
cartridge device and the staple driving device of the second
embodiment are not shown in the figures because the details are
evident from a comparison with the first embodiment.
* * * * *