Suture materials

Quick review of basic suture materials, needles and techniques for medical students and surgery residents

1. Dr Amruta Unawane (General Surgery) Suture materials

2. Definition Suture material – Artificial fibers used to hold traumatized tissue together till natural scarring and healing takes place

3. Goals of Suturing Apposition of wound edges To provide adequate tensile strength Maintain hemostasis Aid in wound healing Prevent wound infection Reduce scarring and achieve asthetically appropriate wounds

4. Ideal suture material Universally applicable to all types of tissue Easy to handle- No kinks, coiling, twisting Inert – Does not generate tissue reaction Strong – High tensile strength Frictionless – causing less tissue trauma Secure for tying reliable knots (non –slip) Able to be sterilized without composition changes Resists bacterial growth In certain areas, absorbability should be possible NON ALLERGIC, NON CARCINIGENIC NON ELECTROLYTIC COST EFFECTIVE

5. Characteristics of suture material Tensile Strength Force required to break when pulling two ends apart Depends on type of suture Thickness of suture Purpose for which being used Knot strength Force required for a knot to slip – considered when ligating arteries Memory Tendency to return to original shape (untied) Tendency to stay in one position

6. Plasticity – Ability to expand when stretched and not return to its original length (Loosens with edema) Elasticity – Ability to return to its original length after stretching, helpful in odematous tissue. Fluid absorption & capillary action: The tendency for the suture to absorb water and facilitate infection Breaking Strength Rate (BSR): Approximate days after placement when 50 % of breaking strength remains.

7. Suture Needle Made of either stainless steel or carbon steel Parts Tip/point Body/shaft Eye/swaged end

8. Needle Properties Sharp enough to penetrate tissue with minima resistance Rigid enough to resist bending or breaking Sterile and corrosion resistant to prevent infections Stays stable in the grasp of needle holder Ductility – Needle’s resistance to breaking under a given amount of bending

9. Technical specifications Needle Length 6mm, 8mm, 12mm, 18mm, 22mm, 30mm, 35mm, 40mm, 50mm Cross Section- round, cutting, reverse cutting, tapercut , micro-point spatula curved Needle Curvature Straight, ½ circle, ½ circle double, 1/4 th circle, 1/4 th circle double, 3/8 th circle, 3/8 th circle double, 5/8 th circle, loop round

10. Curvature of surgical needles Curved needles allow predictable turnout from tissue and require less space for maneuvering

11. Needle curve specifications

12. Cross section of needles

13. Eye (Swage) 3 categories Closed eye – typical household sewing needle type French (Split or spring eye) Having slit from inside the eye to the end of the needle with ridges that catch and hold the suture in place Swaged (Eyeless) - Permanently attached to suture strand by the manufacturer

14. Principle for selecting needle type

15. Classification of Suture Materials According to absorbability Absorbable Non absorbable According to material Natural Synthetic According to structure Monofilament Polyfilament / braided

16. Monofilament Polyfilament Single strand of material Less traumatic Slips easily- more knots needed Resists bacterial harbouring Has more memory Contains several strands Greater tensile strength More flexibility and pliability Knot security May harbour bacteria Mono Vs Polyfilament

17. Monofilament Polyfilament

18. Question to ask when you see suture material -- Is it natural or synthetic? Is it absorbable or non absorbable ? Is it mono filament or polyfilament ?

19. Absorbable Sutures Natural and absorbable sutures elicit more inflammatory reaction than non absorbable and synthetic sutures

20. Absorbable sutures are broken down by Proteolysis ( Eg Catgut) Hydrolysis ( Ex Vicryl , Dexon )

21. Catgut Absorbable, Natural, Monofilament Made from submucosa of sheep intestinal tissue (collagen) Plain catgut is destroyed in about a week Chromic acid delays hydrolysis and keeps it in tissue longer (2-3weeks) High tissue reactivity Uses – Tubal ligation, episiotomy suturing, oral mucosa suturing

22. VICRYL ( polygalactin , braided) Absorbable, synthetic, braided Low elasticity Tensile strength – 65% @ 14 days - 40% @ 21 days - 10 % @ 35 days Absorption complete by 70 days

23. Polydiaxone (PDS) Absorbable, synthetic, monofilament Tensile strength – 70% @14 days - 50 % @ 21 days -14 % @ 56 days Completely absorbed @ 180 days Other types of absorbable synthetic sutures Polyglycolic acid ( Dexon ), Polygloconate ( Maxon ), Glycomer ( Biosyn )

24. Non Absorbable sutures Natural Synthetic Monofilament Braided Monofilament Braided Stainless steel Silk, Linen Nylon Prolone (Polypropylene) Polyester

25. Silk Natural, non absorbable, polyfilament Has significant tissue reaction and inflammation. Handling and knot tying is very secure Lowest tensile strength Weaker when wet

26. Nylon Non absorbable, synthetic, monofilament Inert, no tissue reaction Significant memory – prone to knotting Surgilon , Ethilon , Dermalon

27. Polypropylene Non absorbable, synthetic, nonofilament Inert High Plasticity – Expands to prevent strangulation but loosens when edema subsides Slips easily – requires extra knots Used for wound closure Prolone , Surgilene , Surgipro

28. Color coding