Suturing | Wound Closure Techniques

What is Suturing?

Suturing is the art and science of approximating wound edges using needle and thread to facilitate healing by primary intention. It is the most common method of wound closure in surgery.

Key Objectives:

Hemostasis — stop bleeding
Wound edge eversion & approximation
Minimize dead space
Support tissue during healing
Optimal cosmetic outcome

Wound Healing Phases

Hemostasis (0–48 hrs)

Platelet plug → fibrin clot → vasoconstriction

Inflammation (1–6 days)

Neutrophils → Macrophages → debridement & cytokine release

Proliferation (4–21 days)

Fibroblasts → Collagen deposition → Angiogenesis → Granulation tissue

Remodeling (21 days – 1 year)

Type III → Type I collagen. Max tensile strength ~80% of original at ~12 weeks

Halsted's Principles of Surgery

1. Gentle handling of tissues

2. Meticulous hemostasis

3. Preservation of blood supply

4. Aseptic technique

5. No tension on tissues

6. Accurate tissue apposition

7. Obliteration of dead space

Absorbable Sutures

Broken down by enzymatic degradation (natural) or hydrolysis (synthetic). No removal needed.

Non-Absorbable Sutures

Permanent. Must be removed or remain indefinitely (e.g., deep fascial closure).

Suture Size Guide (USP)

Size	Diameter (mm)	Common Use
6-0	0.07	Face, eyelids, microsurgery
5-0	0.1	Face, hand, pediatric
4-0	0.15	Skin (extremities), subcuticular
3-0	0.2	Skin, scalp, trunk
2-0	0.3	Deep tissue, fascia
0	0.35	Fascia, abdominal wall
1, 2	0.4–0.5	Ortho, large vessel, sternum

Rule: More zeros = thinner suture. "5-0" is thinner than "3-0".

Surgical Knot Tying

A good knot is secure, flat (low profile), and uses the minimum throws necessary. An insecure knot is the #1 cause of wound dehiscence from suturing error.

Square Knot

Most reliable. Two throws in opposite directions (right-over-left, then left-over-right). Minimum 3 throws for synthetics.

Surgeon's Knot

Double throw first. Extra friction in first throw prevents slippage while second throw secures. Ideal for vessel ligation & under-tension closures.

Granny Knot ⚠️

AVOID! Throws in the same direction. Slips easily and unties. This is the most common beginner mistake.

Throws Required by Material

Material	Min Throws	Reason
Silk	3	High friction coefficient
Nylon (Ethilon)	4–5	Memory, low friction
Polypropylene (Prolene)	5–6	Very low friction, high memory
PDS / Monocryl	4	Monofilament, moderate friction

Surgical Suturing