1. GENERAL CHARACTERISTICS OF SUTURES
Katsan Katgüt San. Tic. A.Ş
1571 sokak No:22 Çınarlı/İZMİR- TÜRKİYE
Tel: +90(232)
Fax: +90(232)
TRAINING PRESENTATION NO 3: EG3/REV00/130616

2. Suture material is used to keep the wound together during healing process and to provide necessary support. Surgery technique, blood circulation, mechanical stress, suture material, stretching technique, radiotherapy, infection and systemic effects are the main factors in the healing process.
Main characteristics to be considered in the selection of suture material;
Tensile strength
Ease of passage through tissue
Knot security
Drag of tissue by suture
Short and long term reaction of tissue
Handling, ease of use of suture and packing property ensuring suture getting out of package with minimum memory.

3. Factors impacting suture selection of operator;
Field of specialism,
Clinical tissue regeneration experiences,
Surgery experience,
Knowledge gained on healing process of tissue,
Knowledge on biological and physical characteristics of various suture materials,
Patient factors (age, weight, general health status, existence of infection)

4. There are two main sections to mention about sutures in surgery: Needles and Sutures
Characteristics expected from an ideal needle are:
High sharpness
Minimal trauma on the tissue
Stability of form
Resistance against corrosion
Smooth surface
Resistant to stripping
Hard enough not to bend, flexible enough to bend without breaking

5. Surgical needles are made out of stainless steel; they ensure high resistance against corrosion.
They have at least 12% chromium in their content as all real stainless steel needles. This provides a thin chromium oxide layer at the surface that protects against oxygen. Resistance against bending and breaking is ensured by adding high amount of nickel.

6. PAY ATTENTION TO FOLLOWING ISSUES WHILE USING SURGICAL NEEDLES
Eyed needle passes through tissue with more space, increases trauma because of tissue traction. Atraumatic needles causes much less tissue trauma.
Composition of the wire, physical characteristics, diameter, design of the needle, shape of the needle point, manufacturing process, needle surface are important factors to provide needle sharpness.
Sharpness of the sharp-pointed needles should be increased by electro honing (electronic grinding), slenderizing the configuration of needle point and angles, and coating with silicone. When the needle is processed electronically, surface is smoothed out and points of the needle are sharpened.

7. The following features should be considered in the use surgical needles;
Needle holder should contact with the needle from one point externally and two points internally,
Needle holder should be placed one third distance from the queue,
Silicone covered needles pass through tissue easily,
Round needle can be used in all types of tissues except skin,
Shaping feature should be minimal,
Needle should be resistant against torsion and deformation, should not break.

8. Characteristics expected from an ideal suture;
1. Elasticity:
It’s a term describing elongation of suture material by means of pulling method then returning to its original length when left free, in short its flexibility. Elasticity is a preferred characteristic in sutures.
Because after implanting the suture to the wound, suture is expected to keep two parts of scar together in suitable position by elongating without stressing, cutting tissues due to edema developed in the scar and then, upon retraction of wound after re-absorption of edema to return to original length.

9. 2. Plasticity:
Plasticity is a term defined as the capacity of a suture to retain its length and strength after stretching.
Sutures with high plasticity do not hinder circulation on the tissue by elongating without stressing or cutting tissues due to developing edema on the wound. However, elongated suture upon retraction of wound after re-absorption of edema cannot ensure correct approximation of wound edges.

10. 3. Memory:
It is a term defining incapability of suture to change shape easily.
Sutures with strong memory tend to return their former, packing form when they are removed from their packing, during and after manipulation.
This is because of their rigidity.

11. 4. Friction Surface: It defines slipperiness of suture.
Suture surface should be smooth and uniform.
However, very slippery and smooth sutures are not preferred due to their unsecure knotting.
Uneven surface of sutures is a desired characteristic for knot security.
Disadvantages of these types of sutures are their leading trauma while passing through tissue and to thrombosis by scratching vein surface.
Such disadvantages are tried to be eliminated by coating such sutures with materials such as silicone.
Multifilament sutures have larger friction surfaces compared to monofilament sutures and they cause more trauma while passing through tissues.

12. Suture materials are generally “coated” for facilitating the usage, especially for decreasing the tissue damage while passing through needle track, and increasing the knot security during knot tying.
Although non-absorbable wax, paraffin wax, silicon, polytetraflouroethylene are conventional coating materials, new coating materials are still in a search especially for absorbable sutures.
The reason is that, coating materials of the absorbable sutures should also be the absorbable but conventional coating materials are not available for the absorbable sutures.

13. Coating materials of the absorbable sutures may be in the form of soluble or insoluble in water.
Water-insoluble materials can remain longer period of the time, dissolved by hydrolysis and produces chemical compounds closer to active ingredient of the suture. (for instance, polyglactin 370 and polycaprolate).
Coatings are used more frequently in multifilament sutures, generally monofilaments don’t require coating.
Although coating of the suture materials facilitates the easy passage from the tissue and usage features, they reduce knot security.

14. 5. Tensile Strength:
It defines the force needed to break the suture. Tensile strength of the suture reduces after implantation.
Tensile strength is related with the diameter of suture and tensile strength increases as the diameter of suture increases.
Tensile strength loss and absorption rate are not the same concepts. Tensile strength of the suture should not exceed the tensile strength of the tissue. Tensile strength of the suture should be as much as tension of the tissues. Thin and low tension sutures should not be used in wounds for high tension tissues.

16. There should be made a distinction between dissolution rate and tensile strength of the suture material.
Dissolution rate and tensile strength loss rate are not the terms interchangeable.
Although dissolution rate is important for suture complications emerged in late phase, when we think the primary aim of the suture which is tissue approximation at recovery period, tensile strength loss rate is more important for surgeons.

17. Knotted suture has 2/3 tensile strength of the knotless suture.
Weakest point of suture is knot. Therefore tensile strength of sutures are measured in knotted condition.
Knotted suture has 2/3 tensile strength of unknotted suture. Each applied knot reduces tensile strength of suture by 30-40% and causes to leave more foreign substance on the tissue.
Volume of the knots is important for the inflammation, not the number of knots.
Square knot than sliding knot, monofilament knot than multifilament knot has less volume.
In an improper stitch, sewing surface would be completely deformed. Diameter differences can be seen through the suturing line, pilling can be seen, surface integrity can be lost. Filaments can be separated from the surface during knotting.

18. Note: Basic Knot Knowledge
Classical Knot;
Surgical suturing is making a loop that holds tissue together and formation of appropriate knot configuration that prevents untying.

19. Note: Basic Knot Knowledge
Knot pattern which legs and loop follow diametrically is named as Granny Knot.

20. Note: Basic Knot Knowledge
Sliding Knot;
As different from classical knot, it’s a knot that occurs from a loop can slide over the constant leg. Again, as different from the classical knot, equal tension is not exerted on both legs. It’s a technique preferred for tying deep tissues which manipulation with the hand is hard.

21. 6. Capillarity:
It defines wicking of fluids by the suture and transmission of fluid wicked throughout the suture.
Sutures with capillarity property carry the serum and bacteria in the region of implantation they have absorbed throughout the suture.
Generally, capillarity of multifilament sutures are higher than monofilament ones.
Sutures with capillarity characteristic used on skin allow passage of microorganisms between external medium and internal medium and lead contamination.
Capillarity characteristics of sutures are minimized by coating with materials such as silicone, Teflon or resin.

22. Multifilament sutures should be avoided in wound with contamination probability; monofilament or absorbable sutures should be used. Monofilament subcuticular sutures with minimum size should be used for wounds where cosmetic results are of importance.
Monofilament (nylon, polypropylene, PVDF) subcuticular sutures with as far as small sizes should be preferred for wounds where cosmetic results are important.
Absorbable sutures should be used in biliary and urinary systems which provides suitable environment for calculus formation.
Reaction formed by used material in the tissue is also important. Stainless steel causes least tissue reactions while chromium catgut causes tissue reaction most.
Suture materials causes reaction can be ordered from less to much as follows; polypropylene, polydioxanone, polyglycolic acid, PGLA, polyester, polyamide, silk, plain catgut.
Retention sutures are used in the cases that primary suture is under risk.

23. Usage Characteristics:
It defines usage quality comprehensively. It includes all physical characteristics of suture such as handling, knot security, friction coefficient and memory.

24. COMPARISON OF MONOFILAMENT/MULTIFILAMENT SUTURES
Monofilament (single bunch-fibrous) sutures are resistant to infection.
High memory,
Less reaction formation,
Slippery,
Difficult to use,
Lost 50% of tensile strength when held with instruments.
Multifilament (multi bunch- fibrous) sutures are soft and provide ease of use.
Resistant to wear.
High tensile strength, flexibility, elasticity and knot security.
But they absorb liquid because of their high capillarity and that may cause to infection.
Tissue passages are hard and induces high tissue damage. Causes to reaction formation.

25. CONSIDERATIONS IN THE SELECTION OF SUTURES
Main purpose in the selection of suture is not to damage the tissue during operation. Sharp dissection is less traumatic than blunt dissection. Approximation of wound edges preventing stress accelerates healing. Don’t prefer distorted knots to tie and don’t tie sutures tightly.
There is no excellent stitch but most suitable suture.
According to researches, it’s determined that only 25% of the surgeons are be able to tie knots properly.
Correct knot tying directly influences knot security, but knot tying techniques are generally not known well.
In a conducted research, tying square knot is requested from gynecologists which are mostly clinical chiefs. But most of the gynecologists have tied sliding knot instead of square knot. Incorrect knot tying may cause serious complications such as incisional hernia, dehiscence.

26. As a result of a clinical study conducted with 19 hospital and 699 surgeons in USA, it’s determined that suture preference is made according to subjective criteria and habits rather than scientific criteria.
At the conclusion section of the study, importance of the suture preference based on scientific criteria is emphasized.
This criteria can be listed as ; Tensile strength,
Ease of passage through tissue,
Knot security,
Drag of tissue by suture,
Short and long term reactions of tissue,
Handling properties,
Ease of use of use of suture,
Packing property ensuring suture getting out of package with minimum memory.

28. THANKS…