Anvil for Surgical Staplers

1. Field of the Invention

The present invention relates to surgical instruments for applying rows of fasteners to body tissue, and more particularly to anvil members employed in such instruments.

2. Background of the Art.

Surgical fastener applying instruments used for applying parallel rows of fasteners to body tissue are well known in the art and are commonly used for transecting or reconnecting body tissue such as intestinal, gastric, or lung tissue. The fasteners can be in the form of staples which are closed by crimping the staple legs, or two part fasteners which are closed by locking together a fastener portion with a retainer portion.

Surgical staple applying instruments are illustrated and described, for example, in U.S. Pat. Nos. 4,633,861; 4,633,874; 4,863,088; 3,079,606; 3,490,675; 3,499,591; and 4,429,695. Generally, such staplers include a forked distal end. The body tissue to be operated upon is held securely between two forks of the instrument and the staples are sequentially applied to the tissue.

One fork comprises staple holding and pushing means. Usually, at least two parallel rows of staples are held in slots oriented transversely to the longitudinal axis of the instrument. Pusher elements are located behind the staples. When a camming bar is moved longitudinally by a drive member the pusher elements are driven through the slots, thereby pushing the staples out into the body tissue. The other fork comprises an anvil, i.e., staple closing means. The legs of the staple penetrate the body tissue and enter staple closing depressions in the anvil where they are crimped.

The surgical fasteners must be properly closed to insure that the body tissue is securely fastened, otherwise bleeding or other complications can occur from poor hemostasis of the fastened tissue. Proper closure of the fasteners requires precise alignment of the two forks of the instrument so that the fasteners are precisely aligned with the closing means. However, bending or deflection of the anvil can occur when the two forks are clamped together with body tissue in between, and this bending can cause misalignment of the staples and the staple closing depressions. Deflection can also occur as a result of vertical forces applied to the anvil during contact by the fasteners. More deflection occurs at the distal end of the anvil. The longer the anvil the greater is the tendency to bend. Hence, one way of dealing with bending is to limit the length of the anvil. But in many applications it is desirable to use a longer anvil, which would be able to lay down longer rows of staples.

Another way of reducing bending is to make the anvil stronger. Anvils are presently fabricated by cold working sheet stainless steel of about 0.05 inches to about 0.075 inches in thickness into the desired shape. Stronger anvils can be made by increasing the thickness of the steel. However, this presents disadvantages insofar as the weight and cost of the anvil, as well as the difficulty of working thicker steel, are increased. Using an alternative, harder material of construction can increase the rigidity of the anvil, but possibly at the expense of sacrificing desirable properties of the stainless steel. Therefore, the need exists to fabricate an anvil which is stronger and more resistant to bending while avoiding the disadvantages just mentioned.

Provided herein is an anvil member for use in apparatus for applying a plurality of surgical fasteners to body tissue. The apparatus includes fastener holder means for carrying a plurality of surgical fasteners in at least two parallel rows, and means responsive to user applied force and movable generally along the longitudinal axis of the apparatus for driving said fasteners from said fastener holder means into a fastener closing surface of the elongated anvil member. The rows of fasteners are aligned with the longitudinal axis of the apparatus and the fasteners are sequentially driven from said fastener holder in a direction transverse to the longitudinal axis of the apparatus by a longitudinally moving cam bar. The anvil is an elongated member including at least one each of lengthwise extending first and second walls generally defining mutually transverse respective planes and each having a distal portion and a proximal portion, the distal portion of said first wall including means for closing the surgical fasteners, and said second wall having at least one elongated indentation extending lengthwise thereon.

A complementary feature to prevent flexing of the anvil when the apparatus is closed onto body tissue includes a deflection preventing member projecting laterally from the proximal portion of the anvil.

FIG. 1 is an exploded perspective view of the fasteners applying apparatus of the present invention.

FIG. 2 is an elevational view of a portion of the cartridge assembly.

FIG. 3 is an exploded perspective view of the anvil tip.

FIG. 4 is a perspective view of the anvil member of the present invention.

FIG. 5 is a sectional view of the anvil member illustrating the deflection preventing member.

A surgical stapler employing the anvil of the present invention is generally of similar construction to the surgical stapler disclosed in U.S. Pat. No. 5,014,899, which is herein incorporated by reference in its entirety.

Referring to FIG. 1, the surgical stapling apparatus 100 of the present invention comprises a first frame 110 including cartridge support 114 which has a distal projection 111 for holding a cartridge assembly, a finger rest 151, a stationary handle 152, locking bar 153, a side plate 112, and a notch 113 in the side plate 112. A cylindrical crosspiece 115 extends laterally across first frame in proximity to the proximal end of the apparatus. A second frame 120 has a pair of hinge plates 121 for hingedly connecting to the first frame 110, a pivotable handle 150, a finger rest 151, and a distal projection 122 comprising an anvil assembly 200. Hinge plates 121 apply leverage force to locking bar 153 to secure the frames 110 and 120 together for assembly. The anvil assembly 200 is formed of a plate with indentations or depressions 230 as shown more clearly in FIG. 4, for crimping the legs of metal staples. Alternatively, the anvil assembly may include means for holding rows of retainer portions of two-part surgical fasteners to facilitate mutual engagement of the fastener and retainer portions of the two-part fasteners. Tip 124 allows distal projection 122 to be more easily positioned in body tissue. The resilient deflectable arm 125 is preferably attached to tip 124. Deflectable arm 125 may be formed integral with the tip 124, or it may be in the form of a separate attachment.

The apparatus 100 and its longitudinally extending parts may be conceptually divided along their length into three portions: a distal portion 160 which extends distally beyond the handle member 150 and 152, a middle portion 161 in the vicinity of hinge plates 121 and locking bar 153 where the leverage forces are applied during assembly of the apparatus, and a proximal portion 162 generally proximal to the finger rests 15 1.

Actuating assembly 130 for driving the surgical fasteners is a replaceable insert which includes a pusher assembly having a thrust knob 131, cam bars 132, and knife blade 133. The actuating assembly or insert 130 further includes a stationary carder 134 for holding cartridge assembly 135. Tip 137 at the distal end of the cartridge assembly facilitates positioning body tissue for fastening. Referring also to FIG. 2, cartridge assembly 135 includes pusher members 136 for pushing surgical fasteners out from their respective slots and into contact with the anvil for closure. Cam bars 132 and knife 133 are mounted at their proximal ends to cam bar retainer 138, which is connected to the thrust knob 131 and which provides a means for transferring manually applied force from the thrust knob 131 to the cam bars 132.

In operation the insert 130 is loaded into the first frame 110, and the instrument is then assembled such that the body tissue to be operated upon is located between the cartridge assembly 135 and the anvil 200. The knife 133 is positioned such that it can simultaneously move along slot 240 (see FIG. 4) in the anvil 200 and slot 141 (FIG. 1) in the cartridge assembly. The instrument is then fired by the surgeon's pressing forward (i.e., distally) on the thrust knob 131.

Referring again to FIG. 2, the cam bars 132 and knife 133 are then moved distally and longitudinally along the instrument in the direction indicated by arrow A. The knife 133 creates an incision in the body tissue (not shown) by means of its distal cutting edge 133a, and the cam bars 132 drive the fastener pushers 136 in a direction indicated by arrow B, which is transverse to that of the longitudinal axis of the instrument. The pushers 136, in turn, drive the fasteners 140 out of their slots 139 and into the depressions 230 in the anvil plate for crimping, thereby fastening the tissue on both sides of the incision. When the operation is completed the used replaceable insert 130 can be disposed, and a new one installed in the apparatus.

FIG. 3 illustrates the anvil tip 124 having prongs 124a and detents 124b on the outer sides of the prongs. The detents 124b are for engaging side slots 250 (See FIG. 4) in the anvil 200.

Referring to FIG. 4, anvil 200 is preferably fabricated from 305 stainless steel sheet of from about 0.068 to about 0.072 inches in thickness. Wall 265 defines a planar tissue contacting surface and contains fastener closing means which can be staple closing depressions 230, as shown, or means for releasably holding the retainer portions of two-part surgical fasteners. Walls 264 are side walls which intersect with wall 265 to define ridges 266 (See FIG. 5), and which define planes transverse to the plane of wall 265. The anvil 200 includes a longitudinal indentation 260 extending along at least one, and preferably both, of the sides 264 adjacent to the tissue contacting surface 265 containing the staple closing depressions 230. The indentation 260 increases the strength of the anvil to reduce deflection during clamping of the body tissue between the anvil jaw and the staple jaw and during firing of the fasteners. The indentation 260 is illustratively centered on each side wall 264.

By way of example, the anvil 200 can have a length L-1 of from about 10.30 to about 10.50 inches, a height H-1 of about 0.35 to about 0.36 inches, and a width W-1 of from about 3.5 to about 3.6 inches. The elongated indentation 260 can have a length L-3 of preferably from 85% to 90% of the length L-1 of the anvil, i.e., from about 9.1 to 9.2 inches. Alternatively, the indentation can extend the entire length of the anvil. The depth D (FIG. 5) of the indentation 260 is preferably from about 0.020 inches to about 0.030 inches. The height H-2 is preferably from about 0.085 to 0.09 about inches. The length L-2 of the rows of staple forming depressions can be up to about from 3.0 to 3.5 inches. These dimensions axe illustrative and represent the size of but one embodiment of the present invention. Anvils of other dimensions are within the scope of the present invention.

The proximal end 270 of the anvil includes upright portions 271 including notch 272 for receiving crosspiece 115 in the first frame 110 to facilitate properly aligned engagement of the first and second frames when assembled.

The anvil 200 of the present invention further includes a deflection preventing member 280 located in the proximal portion 162 of the anvil. Deflection preventing member 280 has an upper abutment surface 281 and projects laterally beyond the side of the anvil. In one embodiment, the member 280 can extend a distance W-2 of about 0.065 inches to about 0.075 inches. The abutment surface 281 optionally can be flush with the tissue contacting surface 265. A notch 282 is located next to the deflection preventing member 280.

Referring to FIGS. 1, 4 and 5, the cartridge support 114 includes an upraised side plate 112 having a notch 113 for cooperatively engaging the deflection preventing member 280. When the apparatus is assembled for use, the abutment surface 281 abuts the bottom of notch 113 thereby preventing flexing of the anvil 200. The deflection preventing member is illustratively located about 3.5 inches from the proximal end 270 of the anvil, which is about midway between the middle portion 161 of the anvil and the proximal end 270.

When the instrument is closed by assembling the frames 120 and 110, and pivoting handle 150 down to secure the hinge plates 121 to the locking bar 153, the deflecting member 280 contacts the bottom edge of notch 113 and acts as a stop. This prevents bending of the proximal portion of the anvil 280, and thereby allowing a greater clamping force to be exerted at the distal end. Additionally, by functioning as a stop in the proximal portion of the anvil, the clamping leverage forces developed by the hinge plates and locking bar 153 are to a greater degree directed to the distal portion of the apparatus where the tissue is clamped, because the proximal portion of the anvil is prevented from flexing. Thus, the present invention encompasses both means for preventing bending of the anvil and for increasing clamping forces on the tissue.

While the above description contains many specifics, these specifics should not be construed as limitations of the scope of the invention, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art will envision many other possible variations that are within the scope and spirit of the invention as defined by the claims appended hereto.