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Surgical Suture Patent
 

Surgical suture and method for preparation thereof

Surgical suture abstract

The invention relates to a surgical suture comprising a copolymer as an essential component, the copolymer consisting of lactic acid (lactide) and .epsilon.-caprolacton as repeating unit, wherein shrinkage ratio of said surgical suture is 5% or less after heat treatment at 60.degree. C. for 20 hours and method for production thereof.

Surgical suture claims

We claim:

1. A surgical suture comprising a copolymer of lactic acid or lactide and .epsilon.-caprolacton in an amount sufficient to reduce the shrinkage ratio of said surgical suture to 5% or less when treated at 60.degree. C. for 20 hours.

2. The surgical suture according to claim 1 wherein molecular weight of said suture determined by GPC ranges from about 100000 to 250000.

3. The surgical suture according to claim 1 wherein a mole percentage of said lactic acid or lactide is about 99.9-50 mole % and the mole percentage of said .epsilon.-caprolacton is about 0.1-50 mole %, based on the total moles of said lactic acid or lactide and said .epsilon.-caprolacton.

4. The surgical suture according to claim 1 wherein tensile strength of said suture is at least 2.5 g/d.

5. The surgical suture according to claim 1 wherein knot-pull strength of said suture is at least 2.0 g/d.

6. The surgical suture according to claim 1 wherein elongation at break of said suture is 50.+-.10%.

7. The surgical suture according to claim 1 wherein knot-pull elongation at break of said suture is 45.+-.10%.

8. The surgical suture according to claim 1 wherein said suture is in the form of a monofilament.

9. The surgical suture according to claim 1 wherein said suture is in the form of a multifilament.

10. A method for producing a surgical suture, comprising the steps of:

(i) melt-spinning a copolymer of lactic acid or lactide and .epsilon.-caprolacton; and

(ii) drawing the melt-spun copolymer of step (i) in hot water.

11. The method for producing surgical suture according to claim 10 further comprising the step of:

(iii) redrawing the copolymer drawn in step (ii).

12. The method for producing a surgical suture according to claim 11 wherein said redrawing step (iii) is carried out at 90.degree.-140.degree. C. under draw ratio of 1.2-2.5.

13. The method for producing a surgical suture according to claim 11 further comprising the step of:

(iv) heating the redrawn copolymer of step (iii).

14. The method for producing a surgical suture according to claim 13 wherein said heat treatment step (iv) is carried out at 90.degree.-130.degree. C. for 0.2-24 hours.

15. The method for producing a surgical suture according to claim 13 comprising the step of:

(v) relaxing the resulting copolymer of step (iv).

16. The method for producing a surgical suture according to claim 15 wherein said relaxation treatment step (v) is carried out at 60.degree.-110.degree. C. for 0.2-20 hours.

17. The method for producing a surgical suture according to claim 10 wherein said drawing step (ii) in hot water is carried out at 60.degree.-90.degree. C. at a draw ratio of 8-12.

18. A method for suturing an open wound of a patient, comprising the steps of suturing said open wound using a surgical suture comprising a copolymer of lactic acid or lactide and .epsilon.-caprolacton in an amount sufficient to reduce the shrinkage ratio of said surgical suture to 5% or less when treated at 60.degree. C. for 20 hours; and knotting said suture.

Surgical suture description

FIELD OF THE INVENTION

The present invention relates to a surgical suture and a method for preparing the suture.

BACKGROUND OF THE INVENTION

A polymer of lactic acid (lactide), and a copolymer of lactic acid (lactide) and the other biodegradable monomer are hydrolyzed in vivo and absorbed. These polymers are applied to biomaterials as follows. For example, biodegradable polymers are utilized as microsphere for DDS; anti-adhesive material in the form of film; a guide tube for regeneration of peripheral nerve; and a surgical suture. In particular, several bioabsorbable surgical sutures made of glycolic acid homopolymer or copolymer chiefly consisting of glycolic acid are on the market. Because of stiffness of polylactic acid (polylactide), polyglycolic acid and like bioabsorbable materials, however, said bioabsorbable materials are difficult to use as a monofilament. Therefore, the bioabsorbable materials are used as braided multifilament to impart flexibility to the material.

However, a suture prepared by braiding a number of multifilament has disadvantages of complicated manufacturing process, higher risk of microorganism infection, etc.

Production of suture consisting of monofilament has been tried in a variety of ways so as to solve said problems and cut costs. Such sutures consisting of monofilament are inferior in workability such as flexibility and ease of knot formation, as well as strength required as suture.

Because melt spinning is not suitable for copolymer of lactic acid (lactide), wet spinning of copolymer of lactic acid (lactide) is tried after dissolving copolymer of lactic acid (lactide) in an organic solvent (Japanese Unexamined Patent Publication 64-56055).

However, complete removal of solvent from monofilament suture produced by wet spinning is very difficult. The suture is inferior in uniformity due to existence of solvent within the suture. Specifically, such suture is likely to be infected by bacteria due to ease of concave and convex formation. Such suture is also likely to be broken due to slip-resistant characteristics during knot formation. In addition, the suture has low breaking strength and requires a large amount of agent for coagulating bath.

It is an object of the invention to provide a monofilament suture for medical use with improved economy and performance.

It is another object of the invention to provide a multifilament suture with improved productivity.

It is another object of the invention to provide a method for producing monofilament suture made of copolymer containing lactic acid (lactide) with outstanding flexibility and smooth handling as well as required strength.


Packaging for surgical suture material
Packaging for surgical suture material

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