Types of Suturing: How to Choose the Right Suture Technique

September 18, 2024

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Most surgical or traumatic wounds need to be closed to facilitate healing. The most common method for this suturing, although staples and surgical glues are used. Suturing involves repairing the skin and deeper tissues (such as subcutaneous tissue and fascia) to support proper healing.

It provides benefits like lower rates of wound separation (dehiscence) and greater tensile strength compared to other closure methods.

Surgical suturing is known as sewing together two structures or tissues using suture threaded on a needle. It can be known as under following headings:

Surgical Needles
Suture Materials
Suturing Techniques

Surgical Needles

These are sharp pointed instruments used for guiding the thread for suturing or passing a ligature around a vessel.

Parts of a needle are tip, body and eye.

Classification of needle basis on its eye

Eyeless needles have suture swaged to it the blunt end of the needle; it causes less trauma. It is more costly and can be used only once. Used for face, blood vessels, etc.
Surgical eye needles are made of high-quality stainless steel. Surgical eye needles with a double spring eye and with a regular eye.

Based on needle shape

Straight needle
Curved needle: ¼ circle, 3/8 circle, half circle, 5/8 circle.
Straight needle used for suturing superficial tissues without using needle holder.
Curved needles traverse the tissues with circular movement, help in working in depth.
Confined operative sites, greater curvature needles are required.

Based on needle edge

A round body needle with rounded tip that separates the tissue fibres rather than cutting them. Used for suturing in soft tissues.
The cutting needle has two opposing cutting edges on outside and 3rd edge on inside curve of the needle. Point looks triangular in cross-section. Used for suturing tough tissues.
The reverse cutting needle has triangular edge like cutting needle. Two opposing cutting edges are on the inside and third edge on outside curve of the needle. Improves strength of needle and increases its resistance to bending in tough tissues.
Taper cut needle has reverse cutting tip limited to the point of the needle which then tapers out to merge smoothly into round cross-section. It combines the initial penetration of reverse cutting with minimized trauma of round body needle. Used for cardiovascular surgery.

Classification of Suture Materials

1. Absorbable: Suture are digested by tissue enzyme and removed by phagocytosis. There are two types.

Natural	Synthetic Materials
Catgut	Polyglactin (Vicryl), poliglecaprone (Monocryl)
Fascia lata	Polyglycolic acid (Dexon-S)
Kangaroo tendon	Polydioxanone (PDS)
Beef tendon

2. Nonabsorbable: Suture remain in the body

Natural	Synthetic	Metals
Silk	Polyamide	Stainless steel
Cotton	Polyester	Silver wire
Linen	Polypropylene	Titanium

Suture material may be monofilament (prolene) or polyfilament (silk). The polyfilament suture may be twisted or braided.

The advantage of monofilament suture is that is does not allow bacteria to lodgement but in polyfilament suture has good knotting property, the drawback is that it allows bacteria to lodge in its fibres.

Principles for Selecting Sutures

Slow healing tissues should be sutures with nonabsorbable sutures like skin/fascia.
Healing tissues should be sutures with absorbable sutures like muscles/intestines.
Cosmetic effect is important use monofilament, non-absorbable sutures of small size. It has minimal tissue reaction, but on the other hand absorbable sutures obtain severe tissue reaction or scar formation.
Use monofilament absorbable in presence of infection, it prevents bacterial lodgement.
Healing is delayed in malnourishment, use of nonabsorbable suture to keep tissue in approximation for longer period.
Always use absorbable sutures for anastomosis of ducts, because in such a situation nonabsorbable sutures meets secretions and will act as a nidus for precipitation of salts leading to stone formation.

Characteristics of Ideal Suture Material

Uniform tensile strength and diameter.
Adequate tensile strength till tissue healing is complete.
Produce secure knots without slipping and cutting.
Minimum tissue reaction.
Allow bacterial lodgement.
Should be nonallergic.
Should be less expensive and freely available.

Properties of Absorbable Sutures

Suture	Source	Tensile Strength	Tissue Reaction	Remarks
Catgut	Collagen from submucosa of sheep’s or cow’s intestine	7-10 days	Moderate	Used in rapidly healing tissues like subcutaneous fat
Chromic Catgut	Catgut treated with 20% chromic acid	3-4 weeks	Moderate	Used in slow healing and infected tissues, ligation of vessels
Polyglactin (vicryl)	Synthetic copolymer of lactide & glycotide	60% at 2 weeks	Minimal	Excellent tissue handling can be used in infected tissues. Less tissue reaction. Used in gut anastomosis, ligation of pedicles (thyroid vessels)
Polydioxanone (PDS)	Synthetic (Polyester Polymer)	70% at 2 weeks, 50% at 4 weeks, absorbed by hydrolysis at 180 days	Minimal	High tensile strength, relatively inert. It glides through tissues due to smooth surface. It is monofilament, so there is a minimal chance of infection. It requires multiple knots for security, it has high cost.
Polyglycaprone (Monocryl)	Synthetic copolymer of glycolite & caproladone	60% at 7 days, 30% at 2 weeks, absorption by hydrolysis at 90-120 days	Minimal	High initial tensile strength, relatively inert, not affected by infection, smooth surface, high cost and require multiple knots. Used for gut anastomosis.

Properties of Non-absorbable Sutures

Suture	Source	Tensile Strength	Tissue Reaction	Remarks
Silk	Silkworm	6 months	Moderate to high	Easy handling & knotting doesn’t become limp or brittle. Avoid infected tissues. Used in skin sutures, vessel ligation, gut anastomosis
Cotton	Vegetable origin	50% at 6 months	Minimal	Easy knotting and handling, cheap and freely available. Avoid infected tissues. Used for skin suturing and vessel ligation.
Stainless Steel Wire	Alloy of iron, nickel and chromium	Infinite	Minimal	Used for interdental wiring in fracture mandible, bone suture in fracture patella. Poor handling, knot may break, skin discomfort.
Polypropylene (prolene)	Synthetic polymer of polypropylene	Infinite	Minimal	Resists infection because it is monofilament. Very smooth and glides through tissues. Prolonged tensile strength even in infected areas. Multiple knots required due to poor knotting. Useful in vascular surgery because it is less thrombogenic.
Nylon	Synthetic polyamide polymer	15-20% loss per year	Minimal	Less irritant, cheap, knot is slippery. Infection rate is high due to cervices in braided nylon. Used for skin sutures, tendon repair.

Different types of Surgical Knots

1. Reef Knot

Commonly used knot with advantage that is does not slip.
Draw the ends in the right direction to keep the knot square, while tying the knot.

Fig1: Method of Tying Reef Knot with Left Hand

2. Granny Knot

Knot that’s often tied by mistake instead of a square knot.
Considered inferior to the square knot and insecure, it can slip suddenly.

3. Surgeon’s Knot

Tissues are approximated forcefully, there is tension on the suture.
Likely to slip after the first knot is tied.
The first twist is doubled so that it does not slip.
Useful if thicker type of suture material is used or suture material is slippery.

Alternatives to Types of Sutures

1. Skin Adhesive Strips

Sterile self-adhesive tapes give cosmetic results due to minimum scarring.
Applied on clean wounds without any tension and give minimum scarring.
Transparent adhesive films (Tegaderm, Opsite), with additional advantage allowing inspection of wound and protect it from risk of infection.

2. Tissue Glue

Solution of n-butyl-2-cyanoacrylate monomer.
To apply tissue glue, the laceration should be dry, and the glue should be squeezed from the container tube into the wound.
Keep the wound edges together and hold for 1 minute, wait till the glue dries up.
Glue forms a firm adhesive bond at the site of wound.
Useful in closing facial lacerations in uncooperative children since it avoids local anaesthesia injections.

3. Skin Clips

Applied on approximated wound edges with a skin stapler.
Clips do not penetrate the full thickness of wound edges.
Minimum cross marks with very neat scar and decreased chances of wound infection risk.
More expensive and require special instrument for clip removal.

4. Subcuticular Stitch

Known as continuous suture, where the needle enter & exits from epidermis with plane of the skin.
Stitches are used to close superficial skin edges and typically offer the best cosmetic outcome.

Multiple Choice Questions (MCQs)

Q1. Which of the following is a non-absorbable suture?

A. Polypropylene
B. Vicryl
C. Catgut
D. Polydioxanone

Ans. A. Polypropylene

Q2. Surgically used suture material polydioxanone is:

A. A non-absorbable and remains encapsulated
B. Undergoes hydrolysis and complete absorption
C. Undergoes phagocytosis and enzymatic degradation
D. Is specifically used for heart valves of synthetic grafts

Ans. B. Undergoes hydrolysis and complete absorption