Note: Descriptions are shown in the official language in which they were submitted.
~080073 ETH-395
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ackground o~ the Invention
Thls in~ention relates to needle-suture combi-
nations and partlcularly to a combination of a surgiçal
needle with a ~uture in ~hlch the ~orce neces~ary ~
~eparate the needle from the suture is within an accep~able . -
range for convenlent removal of the needle from the suture
by a ~h~rp tug. . ~ . .
In many surglcal procedure~, sur~eon~ use a .:
technlque whlch employ~ a non-needled ~uture and an
eyed needle. The needle i8 threaded by the nUr~e ~nd
the ~urgeon take3 one pass through the tlssue w ~ng
needleholder. He slip~ the needle off the ~utur~, re~urn~
the needle to the nur~e, and is read~ ~or another threaded
needle from the nursec An assi~tant ~ollows behlnd and
tle~ the suture.
Surgeons rind that this technique i8 more ~ mple
than u~ing a needled 1~em and cuttlng the suture with ~
~ci~sor~ a~ter each p~. However, the time required for
threading results in a ~igni~icant wa t~ o~ expensive
operating room time.
The ~ecurity of attachment of eyeles~ need~
to absorbable surgical sutures or to non-absorbable
~urgical sutures i8 prescribed in the U.S. Pharmaco~oeia
Vol. XVIII at Page 944 (also ~ee yL~-rh~ gs~g~
Vol. XYII~ Page 919). It h~ been thq practice of suture
manufacturers in the United States ~and abroad to securely
attach the ~uture to the needle by swaglng or wlth an
adhesive ~o that the minimum pull-out ~tandard reclted in
.
the U.S. Pharmacopoeia i~ met or exceeded.
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To avoid the problems discussed above it has
been ~ound 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 preparing 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 No. 3,890,975 issued on June 24, 1975.
This approach includes inserting into a drilled hole in the
blunt end of the needle one end o~ a braided suture which
has been sized with a resin and is smaller in apparent dia-
meter than the remainder of the suture and then swaging the
needle at its blunt end to provide a controlled degree o~
compression to the end of the suture within the hole. This
approach is particularly directed to needle-suture combina-
tions 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 takes a straight pull o~ a magnitude within that range to
separate the needle ~rom the suture.
Another approach to the problem is described in
co-assigned U.S. Patent No. 3,875,946 issued on April 8,
1975. In this approach sufficient tension is applied to the
suture in a swaged needle-suture combination to move the su~ure
relative to the needle recess and the tension is released
.
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~L086)073
when the force drops to the ranee deslred for the pull-
out Yalue~ the range varying ~or di~erent sizes of suture.
This ~pproach is applicable to a broad range of suture 8iZ~8
includlng sizes as small as 8-o.
The present invention, in one aspect, provides
another approach to the problem and provides for easy
separation of needles from needle suture combination~ with-
out re~uiring any ma~or change in the manner o~ manu~acture
of the needle-suture comblnations.
There has been another problem ln needle-suture
combinations, unrelated to and independent o~ the problq~
o~ providlng controlled pull-out value~, namely the problem
in cert~in applications, of leakage in sewn tissues ~hrou~h
needle holes made during surgical sewing.
In a typical needle-suture combination in which
the suture ls held within a recess of the blunt end of a
needle, the suture i8 0~ about the same dlametel as tor
somewhat smaller than) the diameter of the recess and is
thus ~maller than the external diameter o~ the needle. In
the surglcal sewing of certain tissues, such &8 blood ves6els
or bladder walls, it is undeslrable to have unfilled or
partial}y unfllled needle holes in the tissue because such
unfilled holes provide paths ~or undesired leakage. In
the case o~ a bladder repair there can be leakage of urine
which can be ha~m~ul in the abdominal cavity and in thç ca~e
o~ blood vessel repair there can be leakage of blood onto ~-
surrounding body -ti~sues.
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This invention, in another aspect, provides a ~:~
means to avoid leaving partially unfilled needle holes in :~
surgically sewn tissue by providing a needle-suture combi- . .
nation in which the extended transverse dimensions of the .
needle and the suture are substantially equal.
Brief Summary of_the Invention .
In accordance with the present invention,. from a
broad aspect, there is provided a needle-suture combination
comprising a needle having a sharp end and a blunt end with
an axial opening extending into the blunt end, and a suture,
.. ....... .
one end of which is positioned within the needle opening
and secured therein whereby the suture is attached to the :.
needle. The needle-suture combination is characterized in
that a segment of the suture at the end attached to the
needle is reduced in cross-sectional area and mass as .
compared to the cross-sectional area and mass of the remain- ~ .
der of the suture. ~.
In the aspect of the invention in which it is .
desired to control the pull-~out values for separating the
needle from the suture, the invention provides a weakened
suture segment adjacent the juncture of the needle and the . ..
suture, which suture segment has a rupture strength which ;
is lower than the rupture strength in other portions of the :.
suture and lower than the force necessary to pull the suture .; .
tip out of the needle recess. The rupture strength in the-.
weakened segment may be controlled to a vaIue which makes. ~.
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the needle separable from the suture by a sharp tug, and
preferably to a value between about 3 and about 26 ounces. .
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In the aspect of the invention in which it is
desired to minimize or eliminate any unfil:Led space in
the needle holes made in tissue during surgical sewing,
the outside dimensions of the needle and the suture may
be controlled so that the diameter of the suture (except
at its tip) is substantially as great as, or somewhat
greater than the maximum lateral dimension of the needle.
The invention is particularly applicable to mono-
filament sutures, although it is also applicable to multi-
filament sutures, e.g., covered, twisted and braided sutures,provided that the suture tips are first unified by resin
impregnation, fusing or other technique. By "unified" it
is meant that the treated portion of the suture is trans-
formed from a collection of loose, individual filamenks to
a single, coherent structure. Such unification is commonly
employed in the art to prevent brooming of cut ends and to
facilitate needle attachment. Reducing the diameter of the
tip of a multifilament suture which is not first unified
will produce an undesirable "brooming" effect in which loose
ends of individual fibers of the suture stick out where
they have been severed adjacent the reduced diameter tip.
As stated above, U.S. Patent No~ 3,890,975
teaches swaging in a drilled needle one end of a braided
suture which is unified by impregnating with a resin and
is smaller in apparent diameter than the remainder of the
suture. The smaller diameter suture end in U.S. Patent No.
3,890,975 is obtained by impregnating the suture tip wi~h a
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resin while the suture is under tension. The unified suture
end thus produced has an apparent diameter somewhat smal~er .
than the remainder of the suture because the fibers of the
.... ..
tip are compacted relative to the remainder of the sukure,
but there are the same number of fibers in the smaller dia-
meter tip as in any other portion of the suture. ~
In contrast, in the embodiment of the presentinvention utilizing a braided or other multifilament suture,
the amount of diameter reduction or actual cross-sectional
area reduction at the suture tip is at least 10 percent of
the cross-sectional of the area of the remainder of the -
suture and there is at least 10 percent less suture material
in the cross-section of the smaller diameter suture end than
in the remainder of the suture. ..
To reduce the diameter, or cross-sectional area
of a suture end for the preparation of the needle-suture . .
combination of this invention, the suture end may be ground ;.
down to the desired diameter and to the desired length of
the cutaway portion. The grinding is carried out by known
techniques and in known equipment, such as in a jeweler's
lathe. or in a grinding machine such as that described in
~ritish Patent No. 1,180,~76 of American Cyanamid Company. ....
Another method of producing a suture end of the
desired redu¢ed diameter which is applicable for monoila- ~ -
ment sutures is to produce a continuous monofilament with ~ ~
spaced segments of reduced diameter, each such segment being ~.
cut to provide two reduced diameker suture ends. A continuous ; ~:
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ilD8~073
~ilament o~ this type may be prepared by providing pulsation
during the extru~lon of the monofilament, or periodic par~lal
slowdown of the r~te of polymer feed to the extrusion ori~ices.
The sutures suitable ~or use in the prepara~ion
of the reduced ~uture tip needle-~uture cambinstion of thi~
invention include mono~ilament and multl~ilament sutures
havlng a unlfied tlp. S~ltable ~uture material~ includç
natural materlals such as collagen (lncluding catgut and
extruded collagen), silk, cotkon ~nd llnen, and synthetic
polymer~, such as nylon, polypropylene and polyester~ h
ae polyethylene terephthalate, and homopolymers and co- :
polymer~ of lactide ~nd glycolide. ~.
When the ~uture tip~ are reduced ln area for
providing easy separabillty Or the need}e ~rom the suture
in accordance with one aspect o~ this invention, it ha~
been round that the remalning strength of the ~uture i8
le~ than would be expected lf the stren~th and cros~
sectlonal areas were dlrectly proporkional. For example, : :
the rupture etrength of 2-0 catgut suture reduced to size
5-0 at the tip segment i~ only about 1~ time~ the rupture
strength th~t would be expected based on the relatl~e
areas o~ the original Buture cross section and the cross
s~ction of the reduced portion o~ the suture tip.
,. ..
Wlth multi~ilament suture~, the ent1re cro~s-
sectional area of the sutùre i8 not made up of suture
materl~l since there i~, o~ necessity, some free sp~ce
b~tween the euture atrands. The proportlon o~ the tot;al . .
cro3s-~ectional area of a suture which i~ occupied by the
suture strands iB called "suture denRity".
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The suture densities o~ multifilament ~tructures are cal-
culated from the volume of the ~ample of the ~uture and
the volume of the ~ber therein in accordance with the
rormula: -
D = F
S ;
in which S is the volume oi the suture, F is the volume
of the ~iber, and D i8 the suture density.
For convenience, it ~B best to determine volumes
in samples at fixed lengths of 9,000 meters, or 9 x 105
centlmeters. This is convenient becau~e ~iber denier is
defined as welght ln grRms per 9,000 meters. At this
length, the volume o~ the suture ln cubic centimeters i~;
d2 (~ x 105)
where d is the diameter of the ~uture in centimeters.
The volume in cublc centimeter6 of the lndividual ~ibers,
F, at the same length would be:
(number o~ strands~ (denier per strand~
or `
denior o~ ~uture
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where r i~ the density o~ the suture materlal in grams per
cubic centimeter.
The ~uture ~ensity of mult~filament ~tructures
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may range ~rom about 0.50 to nearly unlty dependlng on the
compactne~s Or the structure. The suture density o~ braided
~utures ~or ex~mple, generally runs ~rom about 0~70 to about
0.95~ and mo~t usuall~ from ~bout o.80 to about 0.92. `-
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The load at whlch a reduced tip suture will ~upture
mAy be estlmated ~rom the equation:
P = ATD
K
wherein P is the rupture load, im pounds;
~ i~ the tensile strength of the suture
material, in pounds per square inch;
A is the area, in square ~nches, o~ the
reduced diameter portion o~ the suture; ~-
D is the suture density o~ the suture~
belng unity in the case o~ a monofilament; ancl
K 18 a constant ~act~r, empirlcally
determined and representlng the degree of
weakening at the reduced tip portion o~ the
suture over and above the weakening to be
expected ~rom its reduced area.
T~e reduced tip area requlred to obtain a deslred
level ffl rupture strength at a tlp portion o~ a suture may
be calculated ~rom another form of the same equatlon~
A ~ D~
in which A,K,P,D, and T are as de~ined above.
~0 It i8 usually de~ired that the suture be rupturable at its reduced tip portion by a force of ~rom about 3 ounces
to about 26 ounces, or from about 0.2 to about 1.6 pounds;
and these limit-s may be inserted ln the above equati jon as
the limiting values for P. Selecting an average P value
of o.8 pro~ides~;1eeway for differences in indlvldual sutures
and ~or dl~erences in the grindlng of their tlpB and &s~ures
rupture strength~ within the desired range ~or mo~t o~ t~e
reduced tip suture~. The value of K i~ experimentally determined
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for each suture material by compar~ng the ~ctual breaking ~ :
strength of a reduced dlameter ~uture to the ~trength cal- . .
culated on the basie of the tensile strength of the material
and the diameter o~ the reduced ~lp. For lexample, a sample
of chromlc c~tgut 1~ known to hare a tensile strength o~
65,000 psi. A size 5-0 catgut would accordingly be expected ~ :
to have a breaking strength of 1.85 pounds. When the tip
o~ a 2-0 catgut 18 reduced to sl~e 5-0, however, the breaking -
strength i8 determlned to be 1.4 pound~, and avalue for K is
computed as ~ or 1.3. Values o~ K ~or other suture
materials are readily determined in a llke manner.
Brie~ Descr~ tion o~ the Inventlon
The invention will become more readlly app~rent
upon con~ideration o~ the ~ollowing detailed description
when taken in connectlon with the accompanying drawings
wherein: ~`
FIG. l is an enlarged elevation, partly in
cross-section Or the blunt end of a needle and the reduced
diameter end o~ a suture before the suture end i8 inserted
into the recess in the blunt end of the needle;
FI~ 2 ls an enlar~ed elevation, partly in cross-
~ection of the ~uture-needle combination of this inventi~
a~ter the ~uture end of FIG. 1 ha~ been in~erted into the
rece6s ln the blunt end o~ the needle and the blunt end has
been swaged; ~ ~
FIG. 3 i~ an enlarged elevation similar to FIG. 2
but showing rupture o~ the suture near its ~uncture to the
needle after application o~ tension thereto;
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FIG 4 is a tran~verse cross-section o~ the suture
at plane 4-4 o~ FIG l; and :
FIG. 5 is a ~ragmentary elevation of a continuous
filament wlth reduced diameter f.rom which sutures with reduced
diameter end~ can be cut.
As may be seen in FIG~. 1 to 3, needle 11 ha~ a
cylindrical hole 12 in it~ blunt end 13 which may be ~ormed ~:
by drilling or closed channel. Suture 14, ~or most of it~
len~th, has about the ~ame diameter as nqedle 11~ but at :~
~uture end 16, the diameter is redùced to ~it into hole 12.
The length of suture end 16 i8 pre~erably somewhat ~reat~r : ;
than the depth o~ hole 12 80 that there is a segment of ,!
suture end 16 extending beyond the ~uncture o~ the ~leedle 7
and the suture when the euture end i~ ~ully ~nserted into
the hole.
The application o~ cold pressure to the blunt end
o~ the needle ~fter insertion of the ~uture end lnto the
hole produces swaged portion 17 at the blunt end of the
needle and compresses the ~uture within the hole to reduce
1ts transver~e dlmension within the hole somewhat~ a~ shown
in FIGS. 2 and 3. ~-
The application of tension to the needle-suture
combination aiter~it ha6 been u~ed during a surgical proce- .
dure re~ults ln rupture o~ the ~uture in the segment oi re-
duced di~meter ad~acent the needle-suture ~uncture, as shown
.
ln FIG. 3. The cross-sectional area 18 o~ the ~uture at the 1,
n~dle end is smaller than the cross-~ectional area in the Y ~ ;
remainder o~ the suture, a8 shown ln FIG. 4. ; ~ ~.
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ETH-395
11~151~)073
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In FIG. 5, monofilament 21 comprises a series o~
segments 22 having the full deslred suture diameter and a
series of short segments 23 of reduced diameter and cross-
sectional area. Segments 22 are twice the desired ~uture
length becau~e they w~ll be cut in hal~ to make two suture~.
Segments 23 will also be cut, as ~hown at 24 so that each
æhort segment provides two suture ends o~ reduced diameter.
Examples 1 to 8
S~mples o~ size 2-0 catgut suture~, having an
outer diameter of O.016 inches were ground at one end to
the diameter Or a 5-0 suture (o.oo6 inches). The ground
down suture ends were inserted into channel~ in needles
normally u~ed ~or 5-0 suture~ and ~waged. For comparison
purposes the opposlte ends of some of the ~utures (which
were o~ normal dlameter) were inserted into channel~ in
needles normally used ~or 2-0 sutures and swaged. The
sample~ were tested ~or needle separatlon values by pull-
out or breaXing and the results were a3 follows:
S~m~le ~ Reduced Diameter End Original Di~meter Ehd
1 17 oz. 482 gm. 6 l/2 lb. 2.~5 kg.
2 23 oz. 652 8 1/4 lb. 3.74
.
3 24 oz. 680 6 l~.2.72 -~
4 27 oz. 765 5 lb.2.27
20 oz. 567 ~ ~ - -
6 21 oz. 595 - ;~
7 21 oz. 595 ~
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8 - 28 oz. 794 -
Average 23 oz. 652 gm. 6 l/2 lb. 2.~5 ~g.
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Examples ~ to 12
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Samples o~ size 3-0 catgut ~utures, having an
outer diameter of 0.012 inches were ground at one end to
the dlameter of a 5-0 suture (o. oo6 inche~ he ground
down suture ends were inserted into channels in needles
normally used ~or 5-0 sutures and swaged. For ~ompari~on
purposes the opposite end~ of some of the ~uture~ (which
were of normal diameter) were inserted into channel~ in
needles used for 3-0 sutures and swaged. The samples were
tested for needle separation values and the results wqre
a~ ~ollows:
Red,uced D1~meter End Ori ~ ,ter, En~
9 24 oz, 680 gm. 5 lb. 2.27 ~g.
27 oz. 765 4 lb. 1~8~
11 31 oz. 679 5 lb. 2,~7
12 19 oz. 539 -
Average 25 oz. 709 gm. 4 2~3 lb. 2.12 kg,
In tho~e in~tances ln which the invention is
utilized to minimize leakage around the suture through
~ewn tissues, the suture tlp is ground down to a diameter
which will permit its insertion into a needle of approxi- ~;
mately the ~ame~dlameter as the remainder of the ~uture.
In conventlonal commercial production, the suture diameter
is always considerably less than the needle diameter. For
examplo, ~ n~edlë having a di~meter o~ 0.026 inches may be
used with sutures r~nging in size from 5-0 (0.004 inche,s)
to 2-0 (0.016 inches). Thus, even the largest suture avail~ " - ~-
able for thls particular needle has only about 62 percent of
the diameter of the needle.
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In accordance w1th one aspect o~ the present
invention, the tip of a catgut suture (0.016 inch diameter)
may be ground down to the size of a 5-0 suture and then
lnserted into a needle having a diameter of 0.017 so tha~
the suture diameter is about 94 percent that o~ the needle
diameter. In this instance, the suture substantially fills
the needle hole made ln the ~ewn tissue and eliminates, or
substantially elimlnates a leakage therethrough.
In the practice of this embodiment o~ the invlention
suture tips are ground down suf~iciqntly to permit th~ suture
to be lnserted into a needle whose diameter i~ ~uch t~t the
3uture dlameter is at le~5t about 85 percent of the needle
diameter. It i8 preferred that the suture diameter be no
greater than the needle dlameter because otherwioe the
suture would have to enlarge its own hole, result~n~ in the
necesslty to apply more tens$on during sewing than would
otherwise be required and ln increased danger of tearing
delicate tissues.
The lnvention has been described with respect
to preferred emOodiments but other embodiments and modi-
flcatlons wlll be apparent to those skilled ln the ~rt.
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