CA1080073A

CA1080073A - Sutures with reduced diameter at suture tip

Info

Publication number: CA1080073A
Application number: CA240,000A
Authority: CA
Inventors: Jonathan F. Greenberg; Robert T. Quade
Original assignee: Ethicon SAS
Current assignee: Johnson and Johnson Medical SAS
Priority date: 1974-11-20
Filing date: 1975-11-19
Publication date: 1980-06-24
Also published as: GB1521999A; IT1052313B; DE2552098A1; US3926194A; DE2552098C2

Abstract

ABSTRACT OF THE DISCLOSURE
A needle-suture combination is provided in which the suture has at its tip within a recess at the blunt end of the needle and extending to a segment adjacent the attach-ment of the suture to the needle, a cross-sectional area and a cross-sectional amount of suture material less than the cross-sectional area and the cross-sectional amount of suture material in the remainder of its length. In one embodiment, the invention provides a weakened segment which permits a surgeon to separate the needle from the suture by a sharp tug. In another embodiment the invention also permits the use of needles having substantially the same external diameter as the suture attached thereto so that the suture in the sewn tissue substantially plugs the needle hole.

Description

~080073 ETH-395 ~.' 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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1080~73 : ~;
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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~os~073 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 , . . 1: , ., ~ .

~08~073 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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. ". ~ ~ ., . ~ . . . . . ... ....... .

. ETH-395 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.
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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 ~ ~ .
where r i~ the density o~ the suture materlal in grams per cubic centimeter.
The ~uture ~ensity of mult~filament ~tructures :~`
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. `-~ ' -~80073 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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108al073 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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11~151~)073 ',.,: :.' '.
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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ILO~)0~73 Examples ~ to 12 '' ~ ' 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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ETH-395 7 . ':
108(~73 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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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A needle-suture combination comprising a needle having a sharp end and a blunt end with an axial opening extending into said blunt end, and a suture, one end of which is positioned within said needle opening and secured therein whereby said suture is attached to said needle, characterized in that a segment of said suture at the end attached to said needle is reduced in cross-sectional area and mass as com-pared to the cross-sectional area and mass of the remainder of said suture.

2. A needle-suture combination of claim 1 wherein said suture comprises a monofilament.

3. A needle suture combination of claim 1 wherein said suture comprises a multifilament suture which is unified at said suture end and which has fewer fibers at said suture end than in the remainder of said suture.

4. A needle-suture combination of claim 3 wherein said suture end is unified by resin impregnation.

5. The needle suture combination of claim 1 wherein said suture comprises a synthetic polymeric material selected from the group consisting of nylon, polyester, and polypropylene.

6. The needle-suture combination of claim 1 wherein said suture comprises a polyester selected from the group consisting of polyethylene terephthalate and homopolymers and copolymers of glycolide and lactide.

7. The needle-suture combination of claim 1 wherein said suture comprises a material selected from the group consisting of collagen, silk, cotton, and linen.

8. A needle-suture combination of claim 7 wherein said collagenous material is catgut.

9. A needle-suture combination of claim 7 wherein said collagenous material is extruded collagen.

10. A needle-suture combination of claim 1 wherein said suture is rupturable adjacent its junction to the needle by a straight pull at a force between about 3 ounces and about 26 ounces.

11. The needle-suture combination of claim 1 wherein said recess is a drilled hole.

12. The needle-suture combination of claim 1 wherein said recess is a closed channel.

13. The needle-suture combination of claim 1 wherein said cross-sectional area (in square inches) at said reduced portion is equivalent to in which P is the desired rupture load, ranging from 0.2 to 1.6 pounds D is the suture density of the suture, T is the tensile strength of the suture material in pounds per square inch, and K is a constant.

14. The needle-suture combination of claim 13 wherein said suture comprises a monofilament and said suture density is unity.

15. The needle-suture combination of claim 13 wherein said suture comprises a braided suture and said suture density is between about .70 and about .95 percent.

16. A needle-suture combination of claim 13 wherein the suture material is catgut, D is unity, and K
is a constant having a value of about 1.3.

17. me needle-suture combination of claim 1 wherein the suture diameter beyond said tip of reduced cross-sectional area has a diameter at least 85 percent as great as the needle diameter but no greater than the needle diameter.