Surgical fastener exhibiting improved hemostasis

A surgical fastener comprising a fastener member and a retainer member is disclosed. The fastener provides improved hemostasis and, desirably, is of a resinous material that is absorbable in the body. The fastener member has prongs which extend substantially perpendicularly from a base to interlock with apertures in the retainer member. The base and the retainer member are substantially equal in length, and each prong extends from a point on the base spaced inward from its respective end of the base. The fasteners are preferably applied by apparatus including a pusher associated with each fastener member and having a particular structural relationship to the associated fastener member.

BACKGROUND OF THE INVENTION 
This invention relates to surgical fasteners (e.g., staples), and more 
particularly to a fastener comprising a fastener member and a retainer 
member and exhibiting improved hemostasis. 
Surgical fastening devices allow a surgeon to fasten body tissue by 
applying surgical fasteners. The fasteners may be applied singly in 
succession or a number may be applied simultaneously. Surgical fasteners 
are often made of metals such as tantalum and stainless steel, which are 
inert. Fasteners of magnesium, which fasteners are gradually absorbed by 
the body, are also known. 
Non-metallic fasteners are also known and may be preferable to metal 
fasteners in some procedures. For example, non-metallic fasteners can be 
made X-ray transparent so that they do not scatter X-rays and therefore do 
not degrade the quality of radiographs as may happen when metal fasteners 
are used. 
On the other hand, objects of non-metallic resinous materials are usually 
too resilient (i.e., elastic) to hold deformed shapes (assuming plastic 
flow does not occur). (As used herein, the term "resinous materials" means 
non-metallic materials, such as natural or synthetic polymers and resins, 
including protein-based materials, which are relatively flexible and 
elastic, and which may or may not be absorbable in the body.) The greater 
elasticity of resinous materials generally makes it impossible to directly 
substitute such materials for the metal in conventional surgical 
fasteners. 
To overcome this problem, resinous surgical fasteners may be made of two 
parts: a fastener member and a retainer member. The legs or prongs of the 
fastener member are driven through one side of the tissue to be fastened 
and the retainer member interlocks with the prongs of the fastener member 
on the other side of the tissue to hold the entire fastener structure in 
place. One such fastener structure and apparatus for applying it are 
disclosed in Green U.S. Pat. No. 4,402,445, issued Sept. 6, 1983, which is 
hereby incorporated by reference in its entirety. 
A frequent goal in fastening tissue is achieving hemostasis along the 
fastener line. Hemostasis is achieved by exerting pressure on the tissue 
from both sides. If metal staples are used, that pressure (hereinafter 
referred to as "hemostatic pressure") is exerted by and between the base 
of the staple on one side of the tissue and the crimped legs on the other 
side of the tissue. In typical crimped metal staples no part of the staple 
extends beyond the ends of the base. Therefore, a second staple can be 
applied very close to the first staple, so that the bases of the two 
staples are in a line. In that case the gap between staples can be quite 
small so that hemostatic pressure is applied uniformly along the entire 
staple line. 
In contrast, when two-part resinous fasteners are used, hemostatic pressure 
is exerted by and between the retainer member and the base of the fastener 
member. In known two-part resinous fasteners the prongs of the fastener 
member extend from the ends of the base. The retainer member is typically 
longer than the distance between the prongs and therefore must extend 
beyond the fastener member base. Accordingly, the bases of adjacent 
fastener members lying in a line are separated by at least the sum of the 
distances by which adjacent retainer members extend beyond the associated 
fastener member bases. Thus, there are gaps between adjacent fastener 
members. Full hemostatic pressure is not exerted on the tissue in these 
gaps. 
One way to make up for the above-mentioned gaps in a line of resinous 
fasteners is to apply the fasteners in two parallel rows, with a linear 
offset between the rows so that the gaps in one row are opposite the bases 
of the fastener members of the other row. However, this doubles the number 
of fasteners that are required and increases the area of tissue affected 
by the fasteners. 
Another typical characteristic of resinous materials is that they are not 
as strong as metals. Surgical fasteners of resinous materials may 
therefore tend to deform during application to tissue. In particular, the 
fastener member prongs may tend to splay or spread apart as the prongs are 
forced through the tissue. One way to overcome this tendency is to provide 
a metal guide pin adjacent each prong to help the prong penetrate the 
tissue without deformation. After the fasteners have been applied, the 
guide pins are withdrawn from the tissue. This guide pin structure has the 
disadvantage that it increases the complexity and cost of the apparatus 
for applying the fasteners. 
SUMMARY OF THE INVENTION 
In accordance with this invention, a surgical fastener that exerts 
hemostasic pressure along its entire length and cooperates with the 
applying apparatus to minimize splaying of the prongs is provided. The 
surgical fastener comprises a fastener member and a retainer member and is 
applied to tissue in a row in which the lengths of the fasteners are in a 
line and in which adjacent fasteners are nearly touching each other. 
The fastener member comprises (1) a base and (2) a pair of substantially 
parallel prongs extending substantially perpendicularly from the base in 
substantially the same direction, each prong being spaced inward from its 
respective end of the base. Preferably, the base is the same length as the 
retainer member. Also preferably, the prongs are substantially equidistant 
from the transverse centerline of the base. 
A fastener-applying apparatus for use with the fastener of this invention 
contains a number of pusher members corresponding to the number of 
fasteners to be fired. A plurality of retainer members and a corresponding 
number of fastener members are positioned within the apparatus. The pusher 
members force the fastener members through tissue into engagement with the 
retainer members by pushing the bases of the fastener members. The length 
of each pusher member parallel to the longitudinal axis of the associated 
fastener member base is substantially equal to the length of the 
associated fastener member base, and each pusher member exerts pressure 
along substantially the entire length of each fastener member base. 
The present invention finds its greatest use with surgical fasteners of 
resinous materials, although the invention may be used with fasteners of 
other materials that have separate fastener and retainer members. A 
preferred resinous material, which is absorbable in the body, is disclosed 
in copending, commonly-assigned Kaplan et al. U.S. patent application Ser. 
No. 436,056, filed Oct. 22, 1982, now U.S. Pat. No. 4,523,591 hereby 
incorporated by reference in its entirety. 
Thus, the present invention provides a surgical fastener that exerts 
hemostatic pressure along its entire length and cooperates with 
fastener-applying apparatus to reduce splaying of the prongs of the 
fastener while the fastener is being applied to tissue.

DETAILED DESCRIPTION OF THE INVENTION 
Surgical fastener 100 in FIG. 1 includes retainer member 104 and fastener 
member 101, which has two prongs 102 depending from base 105. Prongs 102 
are driven through tissue to engage apertures 103, whose sidewalls are 
indicated by dashed lines 103a, in retainer member 104. Both members may 
be made from a resinous material which may or may not be absorbable in the 
body. 
When fastener 100 is applied to tissue, full hemostatic pressure may not be 
exerted in the areas represented by arrows 106 and 107. This can be seen 
more clearly in FIG. 2, which shows two fasteners 100 applied to tissue 
layers 201 and 202. Full hemostatic pressure is exerted along area 203, 
but such pressure may not be exerted in area 204, which includes adjacent 
areas 106 and 107. As a result, there is a gap 205 through which body 
fluids (e.g., blood, plasma) may seep. 
Thus, when using fasteners 100, two offset rows 301 and 302 of fasteners 
are customarily used (see FIG. 3). Because of offset 303 between rows 301 
and 302, each area 204 in one row is opposite an area 203 in the other 
row. Seepage of fluids through any gaps 205 in one row is arrested at 
corresponding areas 203 in the other row. 
The present invention reduces or eliminates the need for a second row of 
fasteners to provide total hemostasis. Fastener 400 according to the 
present invention is shown in FIG. 4. Preferred fastener member 401 can be 
described as "pi-shaped" because of its resemblance to the Greek letter 
pi. Base 402 of fastener member 401 has extensions 403 and 404, which 
extend over areas 106 and 107. The retainer member and the base of the 
fastener member have substantially the same length; the sum of the lengths 
of extensions 403 and 404 is substantially equal to the sum of the lengths 
of areas 106 and 07 of FIG. 1. Thus, hemostatic pressure is exerted 
between extensions 403 and 404 and the corresponding portions of retainer 
member 104 extending beyond each aperture 103. By applying fasteners 400 
close together in a line, total hemostasis can be provided with only a 
single row of fasteners. 
This is illustrated in FIG. 5. There full hemostatic pressure is exerted in 
area 501 as well as in areas 203. That is in contrast to the previously 
known fasteners, as seen in FIG. 2, where full hemostatic pressure may not 
be exerted in area 204. 
Returning to FIG. 4, apertures 103 are usually located symmetrically along 
the length of retainer member 104 so that areas 106 and 107 are 
substantially equal in length. Extensions 403 and 404 of base 402 of 
fastener member 401 are therefore preferably also substantially equal in 
length, with prongs 102 substantially equidistant from transverse 
centerline 405 of base 402. However, these conditions are not necessary. 
It is only necessary that the lengths of the fastener and retainer members 
be substantially the same. That will provide the desired total hemostasis. 
The fasteners shown in FIG. 5 are shown with small gaps between adjacent 
fasteners. These gaps are shown because it is usually necessary to have 
some structure in the fastener-applying apparatus (not shown) to separate 
the channels through which the individual fastener members are guided 
towards the tissue. During application of the fasteners the tissue is 
generally compressed by the fastener-applying apparatus, thereby 
stretching the tissue. When the fastener-applying apparatus is removed 
from the tissue, the tissue tends to resume its former shape. That brings 
the fasteners in the tissue closer together so that they are touching or 
nearly touching. It is desirable that adjacent fasteners in the tissue be 
nearly touching to provide full hemostasis, although there should 
preferably be some gap because it is also desirable that the fastener line 
be somewhat flexible on the tissue. (As used herein, "nearly touching" 
means touching or separated by a gap of between 0 mm and about 0.5 mm.) 
FIGS. 6 and 7 show the beneficial effect of extensions 403 and 404, in 
combination with fastener-applying pushers 701 (which are longer, parallel 
to the longitudinal axis of the fastener member base, than would otherwise 
be employed), in counteracting the tendency of prongs 102 to splay. FIG. 6 
shows known fastener member 101 as it is about to pierce tissue 201 under 
the downward urging of pusher 601 in known fastener-applying apparatus 
(not otherwise shown). FIG. 7 shows fastener member 401 of this invention 
in the same position. In accordance with the present invention, pusher 701 
is longer, in the direction parallel to the base of the fastener member, 
than pusher member 601 for fasteners of comparable size. In particular, 
pusher member 701 is preferably substantially equal in length in the 
above-identified direction to base 402 of fastener member 401, including 
extensions 403 and 404. As a consequence, pusher member 701 contacts 
fastener member 401 along the entire length of base 402. Pusher member 701 
should not be measurably longer in that direction than base 402; 
otherwise, it would prevent adjacent fastener members from being applied 
to the tissue as close together as possible, which is necessary to provide 
hemostasis. In other respects the fastener-applying apparatus may be 
conventional, as exemplified by the above-identified Green patent, 
although the present invention may facilitate the provision of 
fastener-applying apparatus as shown in that patent without the metal 
guide pins. 
During the application of resinous fasteners, because both the tissue and 
fastener member are non-rigid, prongs 102 may tend to bend inward or 
outward. If prongs 102 try to bend inward, the base of either fastener 
member 101 or 401 bows upward as indicated at 602 in FIGS. 6 and 7. Such 
upward bowing is prevented by the presence of pusher 601 or pusher 701 in 
either device. 
If prongs 102 splay or spread apart, the base of either fastener member 101 
or 401 bows downward. As shown in FIG. 6, with known fastener member 101 
base 105 is not prevented from bowing downward as indicated at 603. In 
contrast, for fastener member 401 of this invention, if base 402 tries to 
bow downward, extensions 403 and 404 try to bend upward, as shown in FIG. 
7 at 702 and 703. However, upward movement of extensions 403 and 404 is 
resisted by pusher 701, which is as long as base 402 and exerts pressure 
along the entire length of base 402. Thus, the combination of longer 
pusher 701 and extensions 403 and 404 reduces the tendency of prongs 102 
of the new fastener to splay. 
One skilled in the art will recognize that the inventive principles 
disclosed herein can be practiced in other than the embodiments described, 
and the invention is not limited by those embodiments but only by the 
claims which follow.