Note: Descriptions are shown in the official language in which they were submitted.
58~
sackground of the invention
This invention relates to needle-suture combina-
tions and par-ticularly to a combination of a surgical needle
with a fluid swellable suture in which the force necessary
to separate the needle from the suture remains within an
acceptable range regardless of the moisture content of the
suture.
In many surgical procedures, surgeons use a tech-
nique which employs a non-needled suture and an eyed needle.
The needle is threaded by the nurse and the surgeon takes
one pass through the tissue using a needleholder. He slips
the needle off the suture, returns the needle to the nurse,
and is ready for another threaded needle from the nurse. ;
An assistant follows behind and ties the suture. -~Surgeons find that this technique is more simple
than using a needled item and cutting the suture with a
scissors after each pass. However, the time required for
threading results in a significant waste of expensive
operating room time. i~-~
The security of attachment of eyeless needles to
absorbable surgical sutures or to non-absorbable surgical -~
sutures is prescribed in the U.S. Pharmaco~oeia, Vol. XVIII
at Page 944 (also se~ U.S. Pharmacopoeia, Vol. XVII, page 919).
It has be2n the practice of suture manufacturers in the United
States and abroad to securely attach the suture to the needle ~~by swaging or with an adhesive so that the minimum pull-out
standard recited in the U.S. Pharmacopoeia is met or exceeded.
- 2 -
.,. . ~ . - .- -. . - -
581
To avoid the problems discussed above it has been
found useful to use needle-suture combinations in which the
needle and the suture are readily separable from each other
by a sharp tug. Several methods have been devised for pre-
paring needle-suture combinations in which the pull-out
values, or the force required for separating the needle from
the suture by a straight pull, is within a controlled range.
One approach to this problem is described in ~- ;
co-assigned U.S. Patent ~o. 3,890,975 issued June 24, 1975.
This approach involves inserting into a drilled hole in the
blunt end of the needle one end of the suture which has been
sized with a resin and is smaller in diameter than the re-
mainder of the suture and then swaging the needle at its
blunt end to provide a controlled degree of compression to
the end of the suture within the hole. This approach is
particularly directed to needle-suture combinations wherein
the suture is of large size, i.e., size 4-0 and larger
(diameter greater than 7.0 mils), and produces average pull-
out values of 3 to 26 ounces, indicating that it ta~es a
straight pull o~ a magnitude within that range to separate
the needle from the suture. ~-
An~ther approach to the problem is described in
co-assigned U.S. Patent ~o. 3,875,946 issued April 8, 1975. -
In this approach sufficient tension is applied to the suture
in a swaged needle-suture co~ination to move the suture
. ~ .
''; '
.~ '
~V~
relative to the needle recess and the tension is released
when the force drops to the range desired for the pull-out
value, the range varying for different si~es of suture~ This
approach is applicable to a broad range of suture sizes,
including sizes as small as 8-0.
The methods described above assure pull-out values
within a desirable range at the time of manufacture in needle-
suture combinations of various kinds employing various kinds
of suture materials. With suture materials that are relatively -~
stable dimensionally under storage conditions, the suture will
retain a pull-out value within the desirable range until the `
time of use in the operating room.
With certain fluid swellable sutures, however,
particularly collagenous sutures whether natural collagen
strands, called "gut", or extruded collagen, there i9 ,
considerable variation in the volume of the suture with vary-
ing moisture content therein-and therefore a needle-suture com- `~-~
bination may have substantially different pull-out values at
different moisture contents. The problem is particularly
acute with respect to needle-suture combinations utilizing
collagenous sutures which are packaged and stored in hermeti- `-
cally sealed envelopes containing a tubing fluid (e~g., 90% ~-
volume isopropyl alcohol in water) to maintain the suture in a
pliable state. If the needle-suture combination is manufac~
tured to have a suitable pull-out value when the colla~enous
material is in dry state, it will have too high a pull-out
value after the collagenous material has soaked in the
aqueous alcohol and absorbed water therefrom to expand with-
in the swaged junction. Conversely, if the needle-suture com-
bination is manufactured to have a suitable pull-out value when the
,~,
;8:~ ~
collagenous ma-terial is swelled with water, it will have
too low a pull-out value and may not hold together at
all if it is allowed to stand aft:er removal ~rom the a~ueous
alcohol and the collagenous material starts to dry out.
Summary of the Invention
In accordance with the present invention, there
is provided in a needle-suture combination comprising a
needle with a sharp end and a blunt end and a fluid- ;
swellable suture inserted at one end into a recess in said
blunt end and held therein by swaging, the improvement which
comprises dime~sioning said recess to provide in the swaged
portion of said recess a cross-sectional area equivalent to
from about 150% to about 250% of the cross-sectional area ~
of the suture end therein when said suture is in a non- `
swollen state.
In a preferred embodiment, the recess is a drilled `
hole or preclosed channel and the needle-suture combination ;~-~
is made in a controlled manner with a dry collagenous suture ~;
to provide, while the collagenous material is still dry, a
pull-out value within a desired range and preferably from
a~out 3 ounces to about 26 ounces. For the sake of convenience, `~
the remainder o~ this specification is directed to collagenous - `
fibers which are water-swellable and represent the suture
material of greatest interest with respect to this invention.
It is understood however, that any suture material subject
to swelling in fluid media is included within the scope of
this invention.
;58~ : `
One method of producing needle-suture combinations
with controlled pull-out values utilizes swaging to a control-
led degree of compression on the suture and is described in ;~
the above-mentioned U.S. Patent No~ 3,890,975.
Another method utilizes partial withdrawal of the
suture from the swaged portion until the force required for ~;
continuing the withdrawal drops to a desired value. This
method is described in the above-mentioned U.S. Patent ~o. ~ `
3,875,946.
It is to be understood that the method of this
invention reduces, rather than eliminates, changes in pull- '?'
out values for collagenous sutures with change in moisture `~
content, but that some change in pull-out values is still
to be expected with variations in moisture content. In- ;
creasing moisture content and consequent swelling of the
collagenous material may produce either higher or lower
pull-out values depending on whether there is a predominance
of factors tending to increase pull-out values or a pre-
dominance of factors tending to decrease pull-out values.
As the moisture content of the collagenous material
increases and the suture swells in a cross-sectional area,
there will be an increase in the area of tight engagement
between the suture surface and the inner surface of the
hole in the needle and there will also be some increase
in the pressure at these surfaces despite the provision
for expansion space, as provided in this invention. Both
of these factors tend to increase the pull-out values.
- 6 -
s~
On the other hand, the collagenous material in
a swollen state is weaker and more easily deformed than
collagenous material in a dry state, and this Eactor
tends to decrease the pull-out values.
The net change in pull-out ~alues of the needle~
suture combinations of this invention upon the swelling of
the collagenous material is dependent upon the amount of ~ -
space allowed within the suture hole for the collagenous
suture to swell into and the degree of swelling. '! ' '
Brief Description of the Drawin~s
The invention will become more readily apparent
upon consideration of the following detailed description
when taken in connection with the accompanying drawings
wherein:
FIG. 1 is an enlarged fragmentary perspective ;~
view of the needle-suture com~bination of the invention at
the juncture of the needle and the suture' ~ -
FIG. 2 is a further enlarged cross-sectional
view at plane 2-2 of FIG. 1, showing the needle-suture `
combination of this invention at the time o~ manufacture
and
FIG. 3 is a cross-sectional view similar to
FIG. 2 but after the collagenous suture has swelled. -
Detailed DescriPtion
As may be seen in FIG. 1, needle 11 has a blunt
end 12 containing hole 13 into which one end of suture 14
is inserted, after which flat swaging produces flattened ; ~ ;
portions 15 of the needle which causes deformation of the
portion of the suture within the hole as shown in FIG. 2. ~;
' ~
- 7 -
.:
S~
FIG. 2 shows that spaces 16 o~ controlled size ~-
are present within flattened hole 13 at opposite sides of
suture 14. In accordance with this invention, the total
area within the flattened portion of hole 13, including :.;
the cross-sectional area o~ the dry suture 14 at that point
and the cross-sectional area o both spaces 16 is from
about 150% to about 250% of the cross-sectional area of
suture 14 at that point.
Upon the moistening of the collagenous suture,
it expands in width and occupies at least a portion of
spaces 16, as shown in FIG. 3 and, to the extent that
spaces 16 are available to take up the swelled volume
of the suture, added pressure between the suture tip and :
the inner surfaces of the wall that would otherwise be .
produced by the swelling, is held to a minimum. ;
Examples 1 to 7
A series of natural gut sutures, ranging in size
from 3-0 to 2 ~diameters 0.011" to 0.023") were inserted
in a dry state into holes of various sizes in a series of
needles and pull-out values were determined in both the
dry and wet states. The holes were flattened circles shaped
as shown in FIGS. 2 and 3 and the cross-sectional areas .
were calculated on the assumption that the flattened circle
was made up of two semicircles of diameter equivalent to ~;
the flattened height of the hole with a rectangle between `
them having a width (flat width) equal to the distance
between the centers of the semicircles. The results were as
shown in TABLE I. .. :~
65F~ H-385
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O --I ~ O U~ ~ ~ ~ 1~ ~rS ,
o~ o~ oc~ ot- o~ 0
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7 ~t U~ o t~l~ N U~
N O ~r) o oo ~J O ~ 01~ 0 0
.. .. . .. .. ..
O ~ O ~ O ~U~
~1~ o ~ ~ N ~) OJ ~ ~ ~ .
0~ 0 OC~I 0~0 O~o oC ~ . .
.. .. . .. .. .. ,,~
In ',. .:: .
8~ U~ u~
O C~J O Q~ O O . '
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,
o ~ ~ ~o o~ o~ o cu
l 8'5)~)O~ ~IC~ N O
H (~) O CU O O O O~ O~ O t-- ;
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o ~1 ~ _I cr o ~D~ ~ ~CO ~';;"
Q Q! ~ :`~
OCU 0~ 0~ 03 c~ O~ ::
.. .. .. .. .. ..
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O U'~ O N O N 0~0 O~ O ~l
.. .. .. .. .. ..
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o ~ o U~ o~
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oj cU
.. .. ..
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ol a~ o ~ c~ ~
O N CU~ o~ 0 N ~1 ,~
,Q
o cu o u~8 ,1 ~
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10~58~L
As may be seen from the foregoing data when the
cros3-sectional area in the swaged portion of the needle
recess is only slightly larger than th~ cross-sectional
area of the sutures in a dry state (e.g., in the size 2
suture in the first column where the former is only 114%
of the latter3 the pull-out values for the wet sutures are
much higher than those for the dry sutures. Conversely,
when the cross-sectional area in the swaged portion oE the ~ -
needle recess is far greater than the cross-sectional area
of the sutures in a dry state (e.g., at 305% as in the 3-0
suture in the fourth column) the pull-out values for the
wet sutures are much lower than the pull-out values for the
dry sutures. In the remaining examples in which the cross-
sectional area in the swaged portion of the recess is between
about 150% and about 250% of the cross-sectional area of the
sutures in a dry state, the pull-out values of the dry
sutures and of the wet sutures are of about the same order
of magnitude. - `
The invention has been described with respect to ~ ~
., .
preferred embodiments but other embodiments and modifications
will be apparent to those skilled in the art.
. ,.',
-- 11 --
.. ~ , - ~ : , ... - ,. . . ::
