U.S. patent application number 09/972594 was filed with the patent office on 2004-12-30 for directionally biased staple and anvil assembly for forming the staple.
Invention is credited to Bayer, Hanspeter R., Cunningham, Scott, Racenet, David C..
Application Number | 20040267310 09/972594 |
Document ID | / |
Family ID | 24784415 |
Filed Date | 2004-12-30 |
United States Patent
Application |
20040267310 |
Kind Code |
A1 |
Racenet, David C. ; et
al. |
December 30, 2004 |
Directionally biased staple and anvil assembly for forming the
staple
Abstract
In accordance with the present disclosure a directionally biased
staple is provided for use in all types of surgical staplers having
anvil structure against which the staple is formed. The
directionally biased staple may be constructed in a wide variety of
cross-sectional configurations including rectangular, elliptical,
trapezoidal, etc. All of the configurations are distinguished by
having a bending region requiring more force to twist or malform
the staple than is required to properly form the staple.
Preferably, these staples have Moment of Inertia Ratios on the
order of between about 1.1 to about 3.0. The staple preferably
corresponds in other respects to conventional formed staples, i.e.
having at least a pair of leg members interconnected by a crown
portion wherein the leg members are formed by direct contact with
the anvil. An anvil assembly is also provided for minimizing the
malformation of staples.
Inventors: |
Racenet, David C.;
(Litchfield, CT) ; Bayer, Hanspeter R.; (Meriden,
CT) ; Cunningham, Scott; (Cheshire, CT) |
Correspondence
Address: |
Chief Patent Counsel
United States Surgical
Division of Tyco Healthcare Group LP
150 Glover Avenue
Norwalk
CT
06856
US
|
Family ID: |
24784415 |
Appl. No.: |
09/972594 |
Filed: |
October 5, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09972594 |
Oct 5, 2001 |
|
|
|
09693379 |
Oct 20, 2000 |
|
|
|
Current U.S.
Class: |
606/219 ;
227/175.1 |
Current CPC
Class: |
A61B 17/0682 20130101;
A61B 2017/07264 20130101; A61B 17/115 20130101; A61B 17/072
20130101; A61B 17/07207 20130101; A61B 2017/320052 20130101; A61B
17/0686 20130101; A61B 17/0684 20130101; A61B 17/068 20130101; A61B
17/0644 20130101 |
Class at
Publication: |
606/219 ;
227/175.1 |
International
Class: |
A61D 001/00; A61B
017/08; A61B 017/04; A61B 017/10 |
Claims
What is claimed is:
1. An anvil assembly comprising: an anvil plate having a tissue
contact surface defining a plane and a plurality of anvil pockets
formed therein, each of the anvil pockets having a central
longitudinal axis and including first and second staple forming
cups, each of the first and second staple forming cups having an
outside portion and an inside portion, the inside portion of the
first and second staple forming cups being positioned in close
relation to each other on the central longitudinal axis of the
anvil pocket, the outside portion of the first and second staple
forming cups being positioned in spaced relation to each other on
the central longitudinal axis of the anvil pocket, each of the
first and second cups being defined by sidewalls and an elongated
base surface extending along the central longitudinal axis of the
anvil pocket, wherein the sidewalls of each of the first and second
cups form an acute angle with respect to the plane defined by the
tissue contact surface of the anvil plate at the outside portion of
the cup and become progressively more perpendicular towards the
inside portion of the cup such that the first and second cups are
substantially vertical through at least a portion of the inside
portion of the cup.
2. An anvil assembly according to claim 1, wherein the elongated
base surface is linear along an axis perpendicular to the
longitudinal axis of the anvil pocket.
3. An anvil assembly according to claim 1, wherein the sidewalls
defining the inside portion of each cup are substantially
perpendicular to the plane defined by the tissue contact surface of
the anvil plate such that a substantially vertical trap is formed
in a central portion of each of the anvil pockets.
4. An anvil assembly according to claim 3, further including a
channeling surface formed about at least a portion of each of the
staple forming cups.
5. An anvil assembly according to claim 3, wherein the elongated
base surface is concavely curved along the longitudinal axis of the
anvil pocket.
6. An anvil assembly according to claim 5, wherein the concavely
curved elongated base surface has a radius of curvature r, and the
length of the substantially vertical trap is from about 0.5 r to
about 2 r.
7. An anvil assembly according to claim 6, wherein the length of
the substantially vertical trap is about r.
8. An anvil assembly according to claim 7, wherein the length of
the substantially vertical trap is from about 0.030" to about 0.100
inch.
9. An anvil assembly according to claim 8, wherein the length of
the substantially vertical trap is about 0.050 inch.
10. An anvil assembly according to claim 3, wherein the
substantially vertical trap extends along the entirety of the
length of the inside portion of the staple forming cup.
11. An anvil assembly according to claim 10, wherein the
substantially vertical trap starts in the central portion of the
staple forming cup.
12. An anvil assembly according to claim 11, wherein the
substantially vertical trap starts before the central portion of
the staple forming cup.
Description
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 09/693,379 which was filed on Oct. 20, 2000
and is incorporated herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] This invention relates to formable surgical fasteners and,
more particularly, to directionally biased formable staples for use
in surgical staplers having anvil pockets for forming the staples.
This invention also relates to anvil assemblies including anvil
pockets for use with surgical staplers.
[0004] 2. Background of Related Art
[0005] Surgical stapling instruments have become critical to many
life saving surgical procedures. Surgical staples are usually
mechanically inserted into tissue with surgical stapling
instruments such as those known as anastomosis devices, including
gastrointestinal anastomosis devices and transverse anastomosis
devices. In such devices, the staples are loaded in one or more
elongated rows into a cartridge. A mechanism for pushing, or
driving the stapler is actuated to drive the staples through two or
more sections of tissue toward a deforming anvil. At the conclusion
of the driving operation, the legs of each staple are
conventionally clamped or bent, by the anvil, to a closed
configuration to complete the suture and join the tissue sections
together. Gastrointestinal anastomosis-type devices drive and bend
the staples aligned in a row sequentially in rapid sequence, while
transverse anastomosis-type devices drive and bend all staples
simultaneously. See, e.g. U.S. Pat. Nos. 4,520,817 and 4,383,634.
Circular anastomosis-type devices simultaneously apply annular rows
of staples to tissue. See, e.g. U.S. Pat. No. 4,304,236.
[0006] One type of conventional staple 20, shown in FIGS. 1-3, used
with both gastrointestinal anastomosis and transverse
anastomosis-type surgical stapling devices is made of stainless
steel or titanium. The undeformed staple 20 (FIG. 1) is generally
U-shaped and includes a back span 22 and two legs 24 depending
substantially perpendicularly from the back span. Each leg 24 has a
sharp chiseled end point 26 for piercing body organs or tissue. The
chisel point also creates torque in the staple, allowing it to
form. The staple penetrates the tissue from one side to engage an
anvil spaced apart and located at an opposing side of the tissue.
The staple is bent by having the legs engage and follow an anvil 25
to form a B-shaped closed staple 28 as shown in FIG. 2. In this
closed configuration tissue is compressed between the legs and
backspan of the staple.
[0007] Because of their substantially circular cross-section (FIG.
3), these conventional staples require approximately the same
amount of force to form the staple into its final shape as is
required to twist or malform it.
[0008] For example, referring back to FIG. 3, a conventional round
cross section staple has a moment of inertia in the x forming
dimension (I.sub.x) given by the equation:
I.sub.x=1/4.sub.--r.sup.4
[0009] Its moment of inertia in the y twisting dimension (I.sub.y)
is given by the same equation:
I.sub.y=1/4.sub.--r.sup.4
[0010] Using a round wire stock of uniform 0.009 in diameter
(r=0.0045), 1 I x = I y = 1 / 4 _ ( .0045 ) 4 = 3.22 .times. 10 -
10 in 4
[0011] The Moment of Inertia Ratio, given by the equation:
[0012] is I.sub.y/I.sub.x 2 3.22 .times. 10 - 10 in 4 3.22 .times.
10 - 10 in 4 = 1
[0013] In order to insure accurate and consistent formation of
these conventional staples, considerable research and development
has been conducted in the areas of forming and driving structures.
For example, anvils have been developed with specific coatings
and/or structure, see, e.g. U.S. Pat. Nos. 5,173,133 and 5,480,089.
Also, staple cartridges have been configured with driver structure
to balance forces encountered during staple formation. See,
commonly assigned U.S. Pat. No. 4,978,049 to Green. Thus, to
control and insure consistent staple formation without twisting or
deformation, extremely strict manufacturing tolerances have been
implemented.
[0014] Other types of staples for different types of instruments
are also found in the prior art. Some have non-circular
cross-section. FIGS. 4, 4A and 4B illustrate by way of example a
staple of this type marketed by United States Surgical of Norwalk,
Conn. for use with its MULTIFIRE ENDO HERNIA and ENDO UNIVERSAL 65
staplers. The anvil in these staplers, as shown in FIGS. 4C and 4D,
is adjacent the backspan of the staple as tissue is approached from
only one side. Unlike the staples described above which are formed
by contact of the staple legs with anvil pockets, these staple legs
are bent around an anvil abutting the backspan. This staple has a
side portion H with a height dimension greater than the dimension
of the base portion B (i.e. 0.020 in vs. 0.015 in.).
[0015] The Moment of Inertia Ratio is given by the equation: 3
Moment of Inertia Ratio = Iy Ix = Moment of Inertia Twisting Axis
Moment of Inertia A bout Forming Axis
[0016] where I.sub.x=({fraction (1/12)})bh.sup.3 and
I.sub.y=({fraction (1/12)})hb.sup.3, with h=0.020 in. and b=0.015
in.
[0017] Thus, I.sub.x=({fraction
(1/12)})(0.015)(0.020).sup.3=1.0.times.10.- sup.-8 in.sup.4,
and
[0018] I.sub.y=({fraction
(1/12)})(0.020)(0.015).sup.3=6.0.times.10.sup.-9 in.sup.4.
[0019] Accordingly, 4 Moment of Inertia Ratio = 6.01 .times. 10 - 9
in 4 1.10 .times. 10 - 8 in 4 = .60 / 1 = .60
[0020] This staple is specifically configured to accommodate
twisting during staple formation to permit the legs of the staple
to cross as shown in FIG. 4E. Thus, it is engineered so the force
to form the staple is slightly greater than the force to malform or
twist the staple. The forming is accomplished by bending the staple
legs around an anvil positioned adjacent the inner surface 32 of
the backspan 34.
[0021] U.S. Pat. No. 5,366,479 describes a hernia staple with
adjacent anvil having a height of 0.38 mm and a thickness of 0.51
mm. This staple is formed the same way as in FIGS. 4C and 4D. The
moment of inertia ratio of this staple in accordance with the
foregoing formula is as follows: 5 I x = ( 1 / 12 ) ( .51 ) ( .38 )
3 = 2.33 .times. 10 - 3 I y = ( 1 / 12 ) ( .38 ) ( .51 ) 3 = 4.2
.times. 10 - 3 Moment of Inertia Ratio = 4.2 .times. 10 - 3 2.33
.times. 10 - 3 = 1.8
[0022] This staple for use as described would actually result in
greater force to produce the desired shape. In fact, the staple
legs would likely contact each other before crossing over into
their crossed configuration.
[0023] Thus, it is apparent that this type of hernia staple, i.e.
where the anvil is adjacent the backspan as the tissue is
approached from only one side, is quite different than the staple
of the present invention, e.g. the B-shaped staple, wherein the
legs penetrate through the tissue to contact anvil pockets. These
anvil pockets direct the staple legs to form the staple into a
closed configuration. Thus staple configuration and considerations
of twisting, bending and staple formation of these hernia staples
are inapplicable to these considerations for anvil pocket directed
staples, such as the B-shaped staples.
[0024] It would therefore be desirable to provide a staple
configuration for a staple designed to penetrate tissue and contact
an anvil pocket on the opposing side of tissue, which, in
complement with conventional cartridge and anvil technology,
enhances correct staple formation while reducing
twisting/malformation caused by misalignment or unusual tissue
while minimizing reliance on strict manufacturing tolerances. It
would also be desirable to provide an anvil assembly which would
minimize staple malformations by misalignment or twisting during
formation of the staple.
SUMMARY
[0025] In accordance with the present disclosure a directionally
biased staple is provided for use in surgical staplers having anvil
structure spaced from the cartridge and having anvil pockets
against which the staple is formed as the legs are forced into
contact with the anvil. The directionally biased staple may be
constructed in a wide variety of cross-sectional configurations
including rectangular, elliptical, trapezoidal, etc. All of the
configurations are distinguished by having a bending region
requiring more force to twist or malform the staple than is
required to properly form the staple. Preferably, these staples
have Moment of Inertia Ratios on the order of between about 1.1 to
about 3.0. The staple preferably corresponds in other respects to
conventionally formed staples, i.e. having at least a pair of leg
members interconnected by a crown portion wherein the leg members
come into contact with and are formed by the anvil.
[0026] An anvil assembly is also provided which includes a tissue
engaging surface and a plurality of staple pockets formed therein
and configured to improve the formation of a staple during
formation of the staple. Each staple pocket includes a pair of
staple forming cups and a channeling surface positioned at least
partially about each cup. Each cup includes an inside portion and
an outside portion. The inside portion of each cup is positioned
adjacent the inside portion of the other cup. Each cup includes a
sidewall which defines an angle with respect to the tissue engaging
surface which approaches perpendicular in a direction moving from
the outside of the cup portion towards the inside portion of the
cup. The sidewall defining at least the inside portion of each cup
is substantially perpendicular to the tissue engaging surface of
the anvil assembly such that each staple forming pocket defines a
substantially vertical trap for minimizing misalignment and
malformation of a staple.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Various preferred embodiments are described herein with
reference to the drawings, wherein:
[0028] FIG. 1 is a side view of a conventional staple as known in
the art;
[0029] FIG. 2A is a side view of the staple of FIG. 1 formed into a
"B" configuration;
[0030] FIGS. 2B, 2C and 2D illustrate the staple of FIG. 2 being
formed as the legs, after penetrating tissue, come into contact
with the anvil pockets;
[0031] FIG. 3 is a cross-sectional view of the staple of FIG. 1
taken along line 3-3;
[0032] FIG. 4 is a perspective view of a conventional rectangular
cross-section staple as known in the art which is formed around an
anvil contacted by the backspan;
[0033] FIG. 4A is a side view of the staple of FIG. 4.
[0034] FIG. 4B is a cross-sectional view of the staple of FIG. 4
taken along line 4B-4B;
[0035] FIGS. 4C, 4D and 4E illustrate the staple of FIG. 4 being
formed as the legs are bent by the pusher and the backspan is held
against the anvil;
[0036] FIG. 5 is a side view of a directionally biased staple in
accordance with the present disclosure;
[0037] FIG. 6 is a perspective view of the staple of FIG. 5;
[0038] FIG. 7 is a top view of the staple of FIG. 5;
[0039] FIG. 8 is a cross-sectional view of the staple of FIG. 5
taken along line 8-8;
[0040] FIG. 9A is a side view of the staple of FIG. 5 after it has
been deformed to a "B" configuration;
[0041] FIG. 9B is an end view showing the coplanarity of the AB@
sections of the staple of FIG. 9A;
[0042] FIGS. 10A B 10F are side views showing staple formation of
the staple of FIG. 5 as the staple penetrates tissue and the legs
come into contact with the anvil pockets;
[0043] FIG. 11A graphically illustrates the comparison of the mean
twist (in inches) vs the offset of the conventional staple of FIG.
1 and the novel staple of FIG. 5.
[0044] FIG. 11B graphically illustrates the comparison of the mean
twist (in %) vs the offset of the conventional staple of FIG. 1 and
the novel staple of FIG. 5;
[0045] FIG. 12A is a cross-sectional view of another embodiment of
a directionally biased staple in accordance with the present
disclosure;
[0046] FIG. 12B is a cross-sectional view of another embodiment of
a directionally biased staple in accordance with the present
disclosure;
[0047] FIG. 12C is a cross-sectional view of another embodiment of
a directionally biased staple in accordance with the present
disclosure;
[0048] FIG. 13 is a cross-sectional view of another embodiment of a
directionally biased staple in accordance with the present
disclosure;
[0049] FIG. 14 is a cross-sectional view of another embodiment of a
directionally biased staple in accordance with the present
disclosure;
[0050] FIG. 15 is a perspective view of an endoscopic
gastrointestinal anastomosis-type device for firing the staple of
FIG. 5;
[0051] FIGS. 16-16C are enlarged views showing the staple formation
by the anvil pockets of the instrument of FIG. 15;
[0052] FIG. 17 is a perspective view of a gastrointestinal
anastomosis-type device for firing the staple of FIG. 5;
[0053] FIG. 18 is a perspective view of a transverse
anastomosis-type device for firing the staple of FIG. 5;
[0054] FIG. 18A is an enlarged view of the staple forming anvil and
a portion of the disposable loading unit of the device of FIG.
18;
[0055] FIGS. 18B and 18C are enlarged views showing the staple
formation by the anvil pockets of the instrument of FIG. 18A;
[0056] FIG. 19 is a perspective view of a circular anastomosis-type
device for firing the staple of FIG. 5;
[0057] FIG. 19A is an enlarged view of the staple forming anvil and
a portion of the disposable loading unit of the device of FIG.
19;
[0058] FIGS. 19B and 19C are enlarged views showing the staple
formation by the anvil pockets of the instrument of FIG. 19A;
[0059] FIG. 20 is a perspective view of another embodiment of a
directionally biased staple in accordance with the present
disclosure;
[0060] FIG. 21 is a cross-sectional view taken along section lines
21-21 of FIG. 20;
[0061] FIG. 22 is a front elevational view of the directionally
biased staple shown in FIG. 20 after the staple has been deformed
to the B-shaped configuration;
[0062] FIG. 23 is a side elevational view from the direction of
lines 23-23 of FIG. 22;
[0063] FIG. 24 is a perspective view of an anvil adapted for
attachment to an endoscopic gastrointestinal anastomosis-type
device;
[0064] FIG. 25 is an enlarged view of the indicated area of detail
shown in FIG. 24;
[0065] FIG. 26 is a top partial cutaway view of the anvil shown in
FIG. 24;
[0066] FIG. 27 is a cross-sectional view taken along section lines
27-27 of FIG. 26;
[0067] FIG. 28 is a cross-sectional view taken along section lines
28-28 of FIG. 26;
[0068] FIG. 29 is another enlarged top view of a portion of the
anvil assembly shown in FIG. 25;
[0069] FIG. 29a is a cross-sectional view taken along section lines
29a-29a of FIG. 29;
[0070] FIG. 29b is a cross-sectional view taken along section lines
29b-29b of FIG. 29;
[0071] FIG. 29c is a cross-sectional view taken along section lines
29c-29c of FIG. 29;
[0072] FIG. 29d is a cross-sectional view taken along section lines
29d-29d of FIG. 29;
[0073] FIG. 29e is a cross-sectional view taken along section lines
29e-29e of FIG. 29;
[0074] FIG. 29f is a cross-sectional view taken along section lines
29f-29f of FIG. 29; and
[0075] FIG. 30 is a graph illustrating force vs. deformation of a
staple being formed in a pocket of the anvil shown in FIG. 24.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0076] Preferred embodiments of the presently disclosed
directionally biased staple will now be described in detail with
reference to the drawings, in which like reference numerals
designate identical or corresponding elements in each of the
several views.
[0077] A directionally biased staple 50 in accordance with one
embodiment of the present disclosure is illustrated in FIGS. 5-9.
Referring specifically to FIGS. 5-7, staple 50 has a U-shaped
configuration and includes a pair of substantially parallel legs 52
connected by a crown portion 54 with a bending region 55
therebetween. The legs are shown perpendicular to the backspan and
are substantially straight along their length. Tissue penetrating
portions 56 are preferably formed adjacent a distal end of legs 52.
These penetrating portions 56 may be of any known configuration
which facilitates entry of the legs 52 into tissue to be stapled.
As shown in FIG. 5, the tissue penetrating portions 56 are
preferably formed in a chisel shape with points 58 adjacent inner
facing sides of legs 52.
[0078] In this embodiment, the cross section is preferably formed
in a substantially rectangular configuration as shown in FIG. 8
with x designating the major base dimension (b) and y designating
the minor height dimension (h) of the crown portion of the staple
when positioned in an inverted-U configuration as shown in FIG. 5.
As used herein, the staple is intended to be formed about the x
dimension (x axis). Thus, as illustrated in FIGS. 10A-10F staple 50
is formed downward relative to the page.
[0079] This cross-sectional configuration may be achieved by any
known method including extrusion, rolling, coining, etc.
Preferably, this configuration is accomplished by flat rolling
round wire stock on opposing sides. In the fabrication process, the
stock can be pre-rolled by the wire manufacturer or may be round
wire stock which is rolled into the desired cross-sectional
configuration by the staple manufacturer.
[0080] I.sub.y of the cross-sectional configuration of the novel
staple illustrated in FIG. 5 is given by the equation:
I.sub.y=({fraction (1/12)})(b).sup.3(h)
[0081] For a base dimension b=0.010 in and a height dimension
h=0.008 in,
I.sub.y=({fraction (1/12)})(0.010).sup.3(0.008)
I.sub.y=6.67.times.10.sup.-10 in.sup.4
[0082] I.sub.x is given by the equation:
I.sub.x=({fraction (1/12)})(b)(h).sup.3
I.sub.x=({fraction (1/12)})(0.010)(0.008).sup.3
I.sub.x=4.26.times.10.sup.-10 in.sup.4
[0083] The Moment of Inertia ratio (I.sub.y/I.sub.x) is thus 6 6.67
.times. 10 - 10 in 4 4.26 .times. 10 - 10 in 4 = 1.57
[0084] Similarly, for a base dimension b=0.012 in and a height
dimension h=0.008 in, I.sub.x=1.0.times.10.sup.-9 in.sup.4 and
I.sub.y=5.12.times.10.sup.-10 in.sup.4, yielding a Moment of
Inertia ratio of 1.95.
[0085] Given that I.sub.y defines the dimension corresponding to
proper formation of the staple when fired and I.sub.x defines the
dimension corresponding to twisting and/or malformation, it is
readily apparent that the directionally biased configurations
provide a "functionally similar" forming force as a conventional
round staple while requiring up to twice as much force to twist or
malform when compared to conventional staples. This novel staple
provides a substantial improvement over conventional staples.
[0086] Table 1 below sets forth by way of example Moment of Inertia
Ratios for a variety of sizes and types of novel directionally
biased staples for use in surgical staplers. Clearly staples of
other dimensions are contemplated so long as they have the novel
moment of inertia ratio described herein.
1 I.sub.y/I.sub.x Moment of Staple Height Base Inertia Size (in.)
(in.) I.sub.y I.sub.x Ratio 3.5 mm. .007 .010 5.83 .times.
10.sup.-10 2.86 .times. 10.sup.-10 _2.04/1 Titanim 3.5 mm. .007
.0115 8.87 .times. 10.sup.-10 3.29 .times. 10.sup.-10 _2.70/1
Stainless Steel 3.8 mm. .007 .010 5.83 .times. 10.sup.-10 2.86
.times. 10.sup.-10 _2.04/1 Stainless Steel 4.8 mm. .009 .014 2.00
.times. 10.sup.-9 8.51 .times. 10.sup.-10 _2.35/1 Titanim 4.8 mm.
.007 .0115 8.87 .times. 10.sup.-10 3.29 .times. 10.sup.-10 _2.70/1
Titanim
[0087] Further, as illustrated below, for comparable size staples,
the novel staple configuration provides increased resistance to
twist without changing firing forces.
[0088] For example, twisting stress _b is defined by the equation:
7 _b = M c Iy
[0089] with moment M kept constant at M=1 lb$in.
[0090] For a conventional round 0.009 in. diameter staple: M=1
lb$in; c=0.0045 in; and I.sub.x=I.sub.y=3.22.times.10.sup.-10
in.sup.4, so 8 _b = ( 1.01 b in ) ( .0045 in ) 3.22 .times. 10 - 10
in 4 _b = 13 , 975 ksi
[0091] For the directionally biased staple of FIG. 8 having b=0.010
in and h=0.008 in: M=1.0 lb$in; c=0.005 in; and
I.sub.y=6.67.times.10.sup.-10 in.sup.4. 9 _b = ( 1.01 b in ) ( .005
in ) 6.67 .times. 10 - 10 in 4 _b = 7 , 496 ksi
[0092] Thus, not only is this embodiment of the novel staple more
resistant to twisting and/or malformation, e.g. .sub.--14,000 ksi
for the conventional staple vs. .sub.--7,500 ksi for the novel
staple, it also maintains minimal firing forces. The directionally
biased staple is effectively desensitized against the effects of
misalignment during staple formation while, at the same time
maintaining a minimal firing force. This directionally intelligent
design can reduce malformations caused by misalignment or twisting
as well as reduce the need for very sensitive manufacturing
tolerances for anvils and anvil forming cups, cartridges, etc.
[0093] The benefits of the novel staple can also be appreciated by
reference to the graphs of FIGS. 11A and 11B. Since staples are
forced through thick tissue and the staple cartridge and anvil can
flex as tissue is compressed and can move slightly relative to
another, this affects the point of contact between the staple leg
points and the anvil. For example, if the anvil moves slightly out
of alignment, the staple legs will contact a different point of the
anvil which can affect uniform formation of the staple.
Additionally, due to manufacturing tolerances, the staple points
may not contact the anvil in the exact optimal location. Although
such staple formation is clinically satisfactory and effective, the
novel staple of the present application provides for more uniform
formation of the row of staples and accommodates for manufacturing
tolerances as it is more resistant to twisting. That is, the staple
will have the tendency to bend in the direction of the thinner
dimension which is desired since in this case the thinner dimension
defines the desired bending direction. By relaxing manufacturing
tolerances, the cost of manufacturing is reduced as well.
[0094] As shown in FIG. 11A, the prior art round staple, since the
height and width are the same, can twist in different directions if
there is misalignment between the staple and anvil. Thus the
direction of twisting cannot be controlled. In contrast, the Moment
of Inertia ratio of the novel staple of the present invention
results in reduced twisting. Note that not only is there more
twisting initially with the prior art staple, but as the offset
increases, the amount of twisting in the current staple is greater
at any degree of offset. The percentage of twist is defined as x/d
x 100% wherein x is the distance between the centerline of the
staple and d is the diameter (or width) of the staple.
[0095] FIGS. 12-14 illustrate alternate directionally biased
cross-sectional configurations in accordance with the disclosure.
These cross-sectional configurations all have aspect ratios in the
range of about 1.1 to about 3.0 wherein the x axis designates the
major base dimension (b) and the y-axis designates the minor height
dimension (h) in each of these cross-sections.
[0096] FIGS. 15-19 disclose by way of example several types of
surgical staplers which can utilize the novel directionally biased
staples. Other types of surgical staplers are also
contemplated.
[0097] FIG. 15 illustrates a known endoscopic sequential stapler
100 including an anvil 110 and a staple cartridge 102 having novel
directionally biased staples 50 loaded into the staple cartridge
102 thereof. Referring to FIGS. 16-16C, with anvil 110 and staple
cartridge 102 in an open position (FIG. 16), tissue 120 is
positioned between anvil 110 and cartridge 102 (FIG. 16A). Anvil
110 is now pivoted in the direction indicated by arrow "A" towards
cartridge 102 (FIG. 16B) in a known manner to compress tissue 120
between anvil 110 and staple cartridge 102. Thereafter, staples 50
are ejected from staple cartridge 102 into pockets 122 formed on
anvil 110. Pockets 122 deform staples 50 into a substantially
B-shaped configuration (FIG. 16C). Anvil 110 can now be pivoted to
the open position to permit tissue 120 to be removed from stapler
100.
[0098] FIG. 17 illustrates a known open type sequential stapler 150
including an anvil 152 and a staple cartridge 154 having novel
directionally biased staples loaded therein. Ejection of staples
from stapler occurs in a manner similar to that disclosed in FIGS.
16-16C and will not be discussed in further detail herein.
[0099] FIG. 18 illustrates a known transverse type surgical stapler
200 including an anvil 210 and a staple cartridge 202 having novel
directionally biased staples 50 loaded into the staple cartridge
202. Referring to FIGS. 18A-18C, with anvil 210 and staple
cartridge 202 in an open position, tissue 220 is positioned
therebetween (FIG. 18A). Anvil 210 is now moved in the direction
indicated by arrow "B" to an approximated position towards
cartridge 202 (FIG. 18B) in a known manner to compress tissue 220
between anvil 210 and staple cartridge 202. Thereafter, staples 50
are ejected from staple cartridge 202 into pockets 222 formed on
anvil 210. Pockets 222 deform staples 50 into a substantially
B-shaped configuration (FIG. 18C). Anvil 210 can now be moved to
the open position to permit tissue 220 to be removed from stapler
200.
[0100] FIG. 19 illustrates a circular stapler 300 including an
anvil 310 and a staple cartridge 302 having the novel directionally
biased staples 50 loaded in the staple cartridge 302. Referring to
FIGS. 19A-19C, with anvil 310 and staple cartridge 302 in an open
position, tissue 320 is positioned therebetween (FIG. 19A). Anvil
310 is now moved towards cartridge 302 in a known manner to
compress tissue 320 between anvil 310 and staple cartridge 302
(FIG. 19B). Thereafter, staples 50 are ejected from staple
cartridge 302 into pockets 322 formed on anvil 310. Pockets 322
deform staples 50 into a substantially B-shaped configuration (FIG.
19C). Anvil 110 can now be moved to the open position to permit
tissue 320 to be removed from stapler 300.
[0101] FIGS. 20-23 illustrate another preferred embodiment of the
presently disclosed directionally biased staple shown generally as
400. Directionally biased staple 400 includes a crown portion 410
and a pair of outwardly angled legs 412 with a bending region 414.
Legs 412 define an angle about 5" to about 15" with crown portion
410. Preferably, legs 412 define an angle of about 9" with respect
to crown portion 410. Alternately, other angle orientations are
envisioned. The angle of legs 412 function to retain the staple
within staple receiving slots of a staple cartridge prior to use,
i.e., legs 412 frictionally engage the slot walls of a staple
cartridge to retain the staple within a cartridge slot. Tissue
penetrating portions 416 are formed at the distal end of legs 412
and preferably have a chisel shape with points 418 adjacent inner
facing sides of legs 412. Referring to FIG. 21, staple 400 has a
cross-section having flat top and bottom surfaces 420 and 422 and
semi-circular side surfaces 424 and 426. Preferably, this
cross-section is achieved by rolling top and bottom surfaces of
wire stock. Alternately, other methods including extrusion and
coining may be used to form staple 400. Using the appropriate
formulas, the Moment of Inertia ratio of staple 400 is
approximately 2. Alternately, the dimensions of staple 400 may be
varied in a manner to achieve a Moment of Inertia ratio within the
preferred range of about 1.1 to about 3. FIGS. 22 and 23 illustrate
staple 400 in the formed state wherein staple 400 assumes a
B-shaped configuration.
[0102] There are various methods of manufacturing the surgical
staple. For example, the method could include the steps of flat
rolling the wire stock to form at least one flat surface thereon
and cutting a length of round wire stock to a predetermined length
corresponding to a desired length of a finished staple or extruding
the stock with a flat surface. The stock is bent into a form having
a backspan and a pair of legs wherein the staple has an aspect
ratio of between about 1.1 to about 3.0.
[0103] FIGS. 24-28 illustrate an anvil 500 which is configured for
attachment to a transverse-type surgical stapler such as shown in
FIG. 18. Anvil 500 includes a plurality of staple pockets 510
formed in the surface of the anvil. Each staple pocket 510 includes
first and second staple forming cups 512 and 514 and a channeling
surface 516 disposed around each of the staple forming cups. An
anvil including such a staple forming pocket has been disclosed in
U.S. Pat. No. 5,480,089 filed Aug. 19, 1994, the entirety of which
is incorporated herein by reference. Anvil 500, including staple
forming cups 512 and 514 and channeling surface 516 can be adapted
for use with any of the surgical stapling devices described in the
specification above including endoscopic gastrointestinal
anastomosis-type devices (FIG. 15), gastrointestinal
anastomosis-type devices (FIG. 17), transverse anastomosis-type
devices (FIG. 18) and circular anastomosis-type devices (FIG. 19).
U.S. patent application Ser. No. 09/687,815, filed Oct. 13, 2000,
discloses a transverse anastomosis-type device including such an
anvil assembly. This application is incorporated herein in its
entirety by reference.
[0104] FIGS. 29-29f illustrate in greater detail anvil assembly 500
shown in FIGS. 24-28. Anvil assembly 500 includes an anvil plate
508 defining a tissue contact surface 502 and having a plurality of
staple pockets 510 formed in surface 502 of the anvil plate 508. As
discussed above, each staple pocket 510 includes first and second
staple forming cups 512 and 514 and a channeling surface 516 formed
about at least a portion (preferably the majority) of each of the
staple forming cups 512 and 514. Each staple forming cup 512 and
514 is defined by sidewalls 520 and an elongated base surface 518.
As shown in FIG. 29a each staple forming cup 512, 514 includes an
outside portion O, a central portion C, and an inside portion I.
Outside portion O extends from the outer extent of the forming cup
(shown in FIG. 30f) to central portion C of the forming cup at and
about the deepest portion of the forming cup (see the ends of lead
lines of reference numbers 512 and 514 in FIG. 28). Inside portion
I of each forming cup extends from central portion C of the forming
cup to the highest operative staple leg or tip engaging point at or
near apex 515 of each pocket 510 (See FIG. 29a). Base surface 518
extends axially from adjacent the outer extent of the outside
portions of each of the staple forming cups 512 and 514, as shown
in FIG. 29f, through the central and inside portions of each of the
staple forming cups 512 and 514 and terminates at or near the apex
515 of pocket 510 (e.g., see FIG. 29a).
[0105] Elongated base surface 518 is substantially linear, i.e.,
substantially flat (herein understood to include flat), along its
transverse axis and is concavely or curved along its longitudinal
axis. The substantially linear surface preferably corresponds to
the shape of the points of a staple to be formed thereagainst.
Since the preferred staple has substantially linear tips (See
staple 400 in FIGS. 20-22), the preferred base surface for such a
staple is substantially linear. This provides line-to-line contact
between the flat surfaces of the staple tips and the substantially
linear base surface. By providing a base surface having a shape
that corresponds to the shape of the staple point, friction is
reduced and galling of the staple tip during staple formation is
minimized. The shape of base surface 518 may be altered to conform
to the shape of the staple points of different staples, which may
be rounded, triangular, etc.
[0106] In the preferred embodiment shown, sidewalls 520, which
partly define staple forming cups 512 and 514, are angular as they
extend from the lower portion of the channeling surface to base
surface 518. Side walls 520 gradually become progressively more
vertical (or perpendicular in relation to tissue contact surface
502) along elongated base surface 518 starting from the outer
extent of outside portion O of cups 512 and 514 where sidewalls 520
are widely angular [relative to tissue contact surface 502 or to
the vertical axis VA of the pocket (FIG. 30f)] towards and through
central portion C and inside portion I of cups 512 and 514.
Preferably, the central and inside portions of cups 512 and 514 are
defined by substantially vertical (herein understood to include
vertical) sidewalls 520, such that a substantially vertical trap
522 is formed at least in the central and inside portions of each
staple forming cup. The substantially vertical trap can start at
any suitable location along the longitudinal axis of staple forming
cup 512, 514 (FIG. 30). While it is preferred that the trap begin
in outside portion O of the staple forming cup before or when the
first peak force occurs (FIG. 30), properly formed staples in
accordance with the invention can also be obtained when the
substantially vertical trap starts in the central or inside portion
of the staple forming cup. Briefly, substantially vertical trap 522
functions to align and accurately form staples therein. The
substantially vertical trap can be of any suitable length depending
on, for example, the dimensions and configuration of the particular
staple and staple forming cup, and the desired configuration of the
finished staple. The length of substantially vertical trap 522 is
preferably between about 0.5r and about 2r, where r is the radius
of curvature of each pocket, and more preferably, the length of the
vertical trap is about r. A preferred radius r is from about 0.030
inch to about 0.100 inch, more preferably about 0.050 inch, herein
understood to include 0.054 inch.
[0107] Referring to FIG. 30, as a staple is formed against an
anvil, the force applied to the staple typically will increase as
the staple moves into the staple pocket until the force is
sufficient to buckle or plastically deform the staple. This peak
force applied to the staple is schematically illustrated in the
graph shown in FIG. 30 by the letter AX@ and typically occurs first
when the tips of the legs of a staple engage base surface 518 in
the outside portion of cups 512 and 514, where the legs begin to
plastically deform. The first peak force typically occurs when the
tips of the staple legs strike base surface 518 and move
approximately between the positions shown in FIGS. 10B and 10C. A
second peak force identified by the letter AY@ in the graph shown
in FIG. 30 is applied to the staple to bend the staple legs
upwardly. The second peak force Y typically occurs when a portion
of the legs of the staple is positioned in engagement with base
surface 518, also in outside portion O, of cups 512 and 514
approximately between the positions shown in FIGS. 10D and 10E.
Staple pockets 510 of anvil assembly 500 are preferably configured
as a trough that preferably gradually funnels and directs movement
of the staple tips and legs of a staple being formed into the
substantially vertical trap at least by the time peak forces X and
Y are reached. The substantially vertical trap captures the tips
and the legs of the staples within and along the trap, preferably
including during the peak loads of staple formation. Capturing the
tip and legs of a staple herein means that at least a portion,
preferably the base portion, of the sidewalls of the substantially
vertical trap of the staple forming cup closely confines the staple
tips and legs in a slip fit relationship to minimize lateral or
transverse movement of the tips and legs and positively direct the
staple through the substantially vertical trap portion of the
staple forming cup. By doing so, malformation by misalignment or
twisting of the staple is minimized or eliminated.
[0108] FIGS. 29b-29f show that side walls 520 with base surface 518
form a trough that gradually funnels the tips and legs of a staple
from outside portion O of cups 512 and 514 into a substantially
vertical trap in the outside, central and inside portions O, C and
I, respectively, of the cups, and terminates at or near apex 515 of
cups 512 and 514.
[0109] FIG. 29f shows that the outside portion O of staple forming
cup 514 is widely angled relative to tissue forming surface 502 or
vertical axis VA to provide a large target area to receive the tips
of the staple legs as they are fired into anvil pocket 510.
[0110] FIG. 29e, also taken through outside portion O of forming
cup 514, shows that sidewalls 520 are at a sharper angle relative
to vertical axis VA to more closely guide the staple tips and legs
along forming cup 514.
[0111] FIG. 29d shows that the sidewalls 520 along inside portion
I, although at an angle of about 8.degree., are substantially
vertical relative to vertical axis VA. In FIGS. 29c and 29b, the
sidewalls are shown as vertical. Ideally and most preferably a
major portion of sidewalls 520 of the substantially vertical traps
are actually vertical. It is to be understood that in attempting to
obtain a vertical sidewall, whether the sidewalls are actually
vertical or are substantially vertical may depend on how the anvil
pockets are formed. Preferably, for economic reasons and ease of
manufacture, the anvil is formed from a thin sheet of metal and the
pockets are stamped therein. Since there is some spring back, i.e.,
elastic deformation, during cup formation by stamping, the
sidewalls of the cups will in some instances actually be
substantially vertical. If the anvil is cast or machined, the
sidewall typically truly will be vertical. Thus, in accordance with
the invention, the object is to provide a trough that funnels and
guides the staple tips and legs into an elongated substantially
vertical trap that traps or captures and positively directs the
staple tips and the legs within and along the substantially
vertical trap in its path to or near the apex as the staple is
formed. While it is preferred that the sidewalls of the staple
forming cups that lead to the substantially vertical trap be
angular, such is not essential. Such sidewalls and/or upper
portions of the sidewalls along the substantially vertical trap can
be arcuate (520', FIG. 29g) or otherwise shaped, so long as enough
of the height of the or a lower portion, e.g., "L", of the
sidewalls of the substantially vertical trap are substantially
vertical in order to trap the staple in accordance with the
invention. It is contemplated that "enough of the height of the or
a lower portion of the sidewall" means that the height is at least
about 1/2of the thickness or diameter of the particular staple
being formed. It is contemplated that substantially vertical
sidewalls are those that are less than about 20.degree. relative to
the vertical axis, preferably less than about 15.degree. and more
preferably less than about 10.degree..
[0112] While the parameters of the start, length, configuration and
end of the vertical trap and the substantially vertical disposition
of the sidewalls has been attempted to be explained, it is
understood that these parameters can vary depending on various
factors, for example, the starting staple configuration and its
dimensions and desired final shape, so long as the principle of
capturing the tips and legs of a staple in a substantially vertical
trap is present or employed to capture and positively and direct
the movement and direction of the staple to optimize proper staple
formation.
[0113] The employment of substantially vertical traps in staple
forming cups, especially those having a substantially linear base
surface is especially advantageous for use in connection with the
directionally biased staples disclosed herein, particularly those
having substantially linear tips. This combination is particularly
effective in compensating for variations in the staple
manufacturing and forming systems to minimize the occurrence of
malformed staples, including those malformed because of variations
in the density of the tissue to be stapled, in staple shape,
geometry, or material, and in the configuration of the staple tips,
e.g., uneven angular or rounded.
[0114] Although specific embodiments of the present disclosure have
been described above in detail, it will be understood that this
description is merely for purposes of illustration. Various
modifications of and equivalent structures corresponding to the
disclosed aspects of the preferred embodiment in addition to those
described above may be made by those skilled in the art without
departing from the spirit of the present disclosure which is
defined in the following claims, the scope of which is to be
accorded the broadest interpretation so as to encompass such
modifications and equivalent structures.
* * * * *