CA1066581A

CA1066581A - Manufacture of controlled release fluid swellable sutures

Info

Publication number: CA1066581A
Application number: CA239,822A
Authority: CA
Inventors: Diann J. Walldorf
Original assignee: Ethicon SAS
Current assignee: Johnson and Johnson Medical SAS
Priority date: 1974-11-18
Filing date: 1975-11-27
Publication date: 1979-11-20
Also published as: DE2551737A1; US3924630A; FR2290877A1; IT1052197B; GB1518550A

Abstract

ABSTRACT OF THE DISCLOSURE

A system is provided for preserving controlled-release properties in a needle-suture combination in which a fluid-swellable suture is held by swaging in a recess in the blunt end of a needle. A controlled excess cross-sectional area is provided within the swaged portion of the needle recess to permit swelling of the suture end without excessive change in pressure in the areas where the suture end is pressed by the swaged inner walls of the recess.

Description

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 -.,. . ~ . - .- -. . - -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.

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. ~;
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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. .. :~

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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.

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Claims

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

1. 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 dimensioning 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.

2. A needle-suture combination of claim 1 wherein said suture comprises a water-swellable collagen selected from the group consisting of natural collagen and extruded collagen.

3. A needle-suture combination of claim 2 wherein said combinations are hermetically sealed in a package containing an aqueous alcohol solution.

4. A needle-suture combination of claim 3 wherein said solution comprises about 90% by volume of isopropyl alcohol and about 10% by volume of water.

5. A needle-suture combination of claim 2 wherein the diameter of the dry suture is from about 0.2 to about 0.6 millimeters.

6. A needle-suture combination of claim 1 wherein the suture pull-out value is from about 3 ounces to about 26 ounces when the suture is in a non-swollen state.

7. A needle-suture combination of claim 1 wherein the suture pull-out value is from about 3 ounces to about 26 ounces when the suture is in a swollen state.

8. A needle-suture combination of claim 1 wherein said suture end is compressed within said swaged recess to from about 64% to about 91% of its original dry state diameter.

9. The needle-suture combination of claim 1 wherein said recess is a drilled hole or a closed channel.

10. In a method for making a needle-suture combination in which a needle having a sharp end and a blunt end is attached at its blunt end to a suture comprising a fluid swellable material by the insertion of one tip of said suture into a recess in said blunt end followed by the swaging of said blunt end and the distortion of said recess to bring at least a portion of the inner surface of said recess into tight engagement with said suture tip, the improvement comprising dimensioning said recess to provide after swaging a cross-sectional area in the swaged portion thereof equivalent to from about 150% to about 250% of the cross-sectional area of said suture tip when said suture is in a dry state.

11. A method of claim 10 wherein said swaging is flat swaging.

12. A method of claim 10 wherein said suture comprises a collagenous material.