Sutures, sutures materials and suturing patterns

General veterinary surgery

1. Sutures, Suture materials and suturing patterns Prepared by Ganga Prasad Yadav MVSc ( Vety . Surgery and radiology)

2. Sutures A suture is a thread used for uniting wound edges. Suture material is used for a number of purposes during surgery: Closure of tissues. Ligation of blood vessels. Anchoring of drains and tubes. Atraumatic tissue manipulation with stay sutures. Selection criteria for suture : type of suture material and suture pattern depends on Physical and biological properties of sutures Condition of wound Healing characters of tissues Tensile strength of the tissue

3. Suture holding power of tissues Depends on kind of tissue, its density, direction in which sutures are applied and distance between sutures. Among soft tissues, skin and fascia have maximum suture holding power while fat has minimum. Distance between sutures: For large animals: 1.5 cm; For small animal: 0.75 cm

4. Properties/qualities of suture materials Tensile strength: the ability of a suture material to withstand breakage on stretching it. Functional strength: the strength that it maintains in tissues when used as a suture. Non-capillarity Non-reactivity Should be tolerated by tissues. Flexibility and elasticity Easy to handle Knotable Uniformity Absorbality Smooth surface Economical and readily available

5. Packaging of suture material

6. Types of Suture Materials  Nonabsorbable  Sutures- Nonabsorbable sutures are not dissolved by the body and therefore must be removed.  They are less scarring than absorbable sutures if removed in a timely manner and are primarily suited for use on the skin. Examples: Nylon ( Ethilon ) and Polypropylene ( Prolene ). Absorbable Sutures- Absorbable tissues are dissolved by the body's tissues and therefore do not need to be removed.  They are best suited for use under the skin as they produce a pronounced scar if used externally.  They can also be used if there is concern a patient may not return for suture removal.  Examples: Polyglecaprone ( Monocryl ), Polyglactin-910 ( Vicryl ), Polyglycolic acid ( Dexon ), Gut and Chronic Gut. Braided Sutures- Braided sutures are comprised of several small strands twisted together.  They can be easier to tie than nonbraided sutures however the tiny gaps between suture strands can harbor bacteria increasing risk of infection. Nonbraided Sutures- Nonbraided sutures, also known as monofilament, are made of single strand.  These types of sutures are typically used in skin closure and in wounds where there is risk of infection.

7. Characteristics of suture used in veterinary practice

8. Classification of suture materials Absorbable suture materials: are organic, biodegradable and eliminated from body after a variable period of time through phagocytosis by macrophages or by enzymatic reaction. Absorbable natural suture materials Cat gut: Origin: submucosa of sheep small intestine and serosal layer of bovine small intestine. Composed of formaldehyde treated collagen fibers. Multifilament and have capillary action. Sterilization: by ionizing radiation and ethylene oxide. Preservatives: 85% ethyl alcohol. Cannot be autoclaved (protein get denatured). Absorption time: can be delayed by treatment with chromic acid, iodine, tannin, formalin.

9. Plain catgut has absorption time 10 days and have high tissue reaction. Can be used for parietal peritoneum and vessels Absorption of cat gut is by breaking the molecular bonds by acid hydrolysis and collagenolysis and digestion and absorption by proteolytic enzymes Knot security: poor Advantages Adequate functional strength Easy to handle Gets absorbed. Does not cause strangulation of tissues Disadvantages : Costly, gets absorbed in infection or protein deficiency.

10. II. Collagen Multifilament, absorbable suture material, derived from bovine flexor tendon. Treated with formaldehyde or chromic acid to prolong absorption time. Less tissue reaction than chromic catgut. Gets absorbed within 60 days. III. Kangaroo tendon: Obtained from tail of Kangaroo Has high tensile strength. Used in slow healing tissues or tissues which Require greater strength. Example: Joint capsule and Hernia.

11. IV. Fascia lata : Obtained from bovine fascia lata . V. Cargile membrane: Obtained from bovine caecum . VI. Amniotic membrane: Obtained from amniotic membrane of fetus and is used to repair gap in body tissues.

12. Absorbable synthetic suture materials Polyglycolic acid ( Dexon ): synthetic, non- collagenous , braided, multifilament polymer of glycolic acid. Have less tissue reaction. Absorption by hydrolysis. Polyglactin 910 ( Vicryl ): Braided, synthetic, multifilament material composed of glycolic and lactic acid in a ratio of 9:1. Absorption by hydrolysis. Excellent strength, easy to handle, stable in contaminated wounds and have minimum tissue reaction. Vicryl Rapide : polyglactin 910 that loses its tensile streng more rapid. It has approximately 2/3 rd of tensile strength of polyglactin 910 and losses all tensile strength at 10-14 days.

13. 3. Polydioxanone (PDS II): Synthetic , monofilament More flexible than PGA and Polyglactin . Sterilized by ethylene oxide. Absorbed by hydrolysis. Minimum tissue reaction and good knot security. 4. Polyglyconate : synthetic, monofilament, copolymer of glycolic acid and trimethylene carbonate. Its properties are similar to polydioxanone .

14. Non-absorbable suture materials Resists biodegradation and maintain tensile strength for much longer time, get encapsulated with fibrous tissue (when used inside body). Organic or Natural: Silk: natural fibre obtained from cocoon of the silkworm. Available as a twisted or braided, multifilament suture material and may be coated with beeswax or silicone to reduce tissue drag and capillarity. Although classified as non-absorbable, absorbed by proteolysis and often undetectable in wound by 2 years. Advantages: cheap, readily available, autoclavable , have high knot security. Disadvantages: high tissue reaction (bind with γ -globulin to induce inflammation); in contaminated wound, increases bacterial proliferation by holding blood.

15. 2. Cotton: less irritating, stable to sterilization and has high knot security. Has high capillary reaction. 3. Umbilical tape: ¼ cm wide cotton tape sutures, used to tie umbilical cord of young one, vulvar sutures (vagina/uterus prolapses ) and abdominal hernias. 4. Linen: braided material obtained from vegetable fibres . Good knot security but poor handling characteristics.

16. Synthetic non-absorbable sutures Nylon (Polyamide): mono or multifilament, synthesized from polymerization of hexamethylenediamine and adipic acid. Advantages: Inert, minimum tissue reaction, cheap. Disadvantages: cut sharp ends, can cause trauma if used in serosa ; poor knot security. 2. Vetafil (polymerized caprolactum ): twisted, multifilament, polyamide suture of nylon family and has high tensile strength.

17. 3. Polyester: braided, multifilament; plain or coated with Teflon, silicon or polybutylate . 4. Polypropylene ( surgilene ): multifilament, polymer of propylene. 5. Polypropylene ( prolene / surgilene ): synthetic monofilament composed of polymerized propylene and sterilized by ethylene oxide and maintains tensile strength for upto 2 years. 6. Nylon mesh: used in large ventral hernia. Metallic sutures Stainless steel Tantalum Aluminum Vitallium Silver Surgical staples: Can be absorbable ( lactomer ) or non-absorbable (stainless steel). Pin sutures Wire mesh Fig: Nylon mesh

18. Ligature: Cord or thread used to tie the blood vessels to control bleeding. Most secure method to control hemorrhage. Ligation decreases the chance of slippage of knots. Transfixation ligature: Indicated for larger arteries to prevent the ligature from slipping off the vessel end

19. Suturing Techniques Basic principles for suturing All sutures should be approximated well with least trauma. Tissues should be handled gently. As far as possible small size suture material and needle should be used. Stitches should be placed a li ttle away from incision edges without including large tissue mass. Tight placed sutures are prone to high tension and ischemia. Proper obliteration of the dead spaces should be ensured. Knots should be simple, secure and placed on one side of the incision to avoid interference in healing.

20. Suture patterns Broadly classified into interrupted and continuous suture patterns. These are further classified into six categories: Apposition sutures Inversion sutures Eversion sutures Purse-string sutures Relaxation/Tension sutures Miscellaneous sutures

21. Apposition sutures wound edges are apposition in manner. Used on skin and muscles. Simple continuous Simple interrupted Continuous lock-stitch (ford interlocking) Subcuticular Cross mattress or Interrupted cruciate

22. Inversion suture Edges of wound are inverted. Used in hollow organs like intestine, uterus, stomach etc. to prevent leakage. Examples Lambert suture: Suture passes through serous and muscular layers but not the mucosal layer. Needle bites are at right angles/perpendicular to suture line. Jobert’s suture: Same like Lambert suture but it penetrates mucosal also. Cushing suture: Similar to Lambert except that bite is parallel to incision line. Connel suture: Same as Cushing but needle penetrates all layers including mucosa.

23. Eversion sutures Edges of wound is everted . Examples Horizontal mattress suture Vertical mattress suture

24. Purse-string suture Used to reduce the opening and to invert the lumen of hollow organ. Also used to constrict opening after rectal prolapse and to secure catheters or thoracotomy tubes. Buhner suture: a type of purse-string suture used to treat vaginal prolapse .

25. Relaxation/Tension suture Horizontal or vertical mattress sutures. Overlapping (Vest over pant) suture: Applied on hernial ring where one side of the tissue overlaps on other side. Combination of Lambert and horizontal mattress sutures.

26. Miscellaneous sutures 1.Tendon suture: to counteract muscle-tendon pull and minimize adhesions so as to restore original tensile strength. Bunnels Technique Bunnel’s Mayer technique Locking loop suture pattern Far-near near-far suture technique Three-loop pulley

27. 2.Staple suture: compression suture requires for obliteration of space. Example: used in Ear hematoma.

28. 3. Stay or Retention suture: Used to retain gauze in wound to protect suture line or retain urinary catheter in place.

29. Time of removal suture Face- 5 to 7 days Neck- 7 days Body and upper extremity- 10 to 14 days Lower extremity- 14-21 days Ear hematoma – 21 days

30. Suture needles Ideal suture needle should be: Of high quality stainless steel Of the smallest diameter possible Stable in the grasp of needle holder Capable of allowing passage of suture material with minimal trauma Sharp enough to pass through tissue with minimal resistance Sterile Resistant to corrosion Strong enough to resist deformation during normal working conditions

31. Parts of needle : attachment end (eye), body and point. Eye of the needle : 1. Closed eye 2. French eye 3. atraumatic eye (swaged suture) Shape of needle : a range of different needle shapes is available: Curved needle: Used in deep wounds with restricted access. Straight needle: Passed through the tissues with the hands rather than using instruments. Example: Used in Aural hematoma. Half-curved needle J- shaped needle Needle point: different types of needle point available Round bodied needle: Friable tissue (Kidney, Liver) Cutting needle: Tough tissues (skin, sternum) Reverse cutting needle: Tendon, subcuticular suture Side cutting needle: Eye surgery

32. Surgical knots Surgical knots are the knots used to bind suture materials together while binding tissue in surgery. Types of surgical knots: Square knot/reef knot: commonly used surgical knot and consists of one throw superimposed by another in the reverse direction. Granny knot/slip knot: consists of two throws, one superimposed by another but not in reverse direction, so, there is more chances of slipping of knot.

33. 3. Surgeon’s knot: first loop is made by taking two turns of one of the suture ends against the other, and second loop is similar to that of a square knot. 4. Double surgeon’s knot: it is actually a surgeon’s knot plus square knot. It is recommended when using suture materials likely to slip.