Sutures: definition

Classification of sutures

1. By absorption: absorbable or non-absorbable
2. By filament structure: monofilament or multifilament/braided
3. By origin: natural or synthetic
4. By size: for example 2-0, 3-0, 4-0, 5-0
5. By needle type: taper, cutting, reverse-cutting, etc.
6. By technique: interrupted, continuous, mattress, subcuticular, and others.

1. Absorbable sutures

Main uses

• Subcutaneous tissue and deep dermis
• Mucosa, such as oral or vaginal mucosa
• Bowel and urinary tract
• Fascia, when a delayed-absorbable material is selected
• Internal ligation of small vessels
• Skin closure in selected patients, particularly children or patients unlikely to return for removal

Types of absorbable sutures

Important points

• Absorption does not mean that the suture remains strong until it disappears. Tensile strength commonly declines earlier.
• Natural gut is degraded mainly by enzymatic processes and may produce a more variable inflammatory reaction.
• Synthetic absorbable materials are mainly degraded by hydrolysis and tend to have more predictable strength loss.
• For low-tension intradermal closure, poliglecaprone is commonly suitable. For high-tension or slow-healing tissues, a longer-lasting material such as polydioxanone may be selected.
  Roberts and Hedges’ Clinical Procedures in Emergency, p. 41-4.

2. Non-absorbable sutures

Main uses

• Superficial skin closure
• Tendon repair
• Vascular surgery
• Hernia repair and fixation
• Retention sutures
• Areas under sustained tension

Types of non-absorbable sutures

3. Monofilament versus multifilament sutures

Monofilament

Advantages

• Less tissue drag
• Lower capillarity, so less potential bacterial wicking
• Less tissue reaction
• Preferred where infection risk is a concern

Disadvantages

• More difficult to handle
• Greater package memory, so it may curl
• Lower knot security, so extra throws may be required
• Can be damaged if crushed with instruments

Multifilament or braided

Advantages

• Flexible and easy to handle
• Better knot security
• Less memory

Disadvantages

• Greater tissue drag
• Interstices may permit capillary movement of fluid and bacteria
• May be less suitable in infected or contaminated wounds

4. Natural versus synthetic sutures

Natural

• Gut: absorbable, collagen-derived
• Silk: non-absorbable braided natural fibre
• Cotton/linen: rarely used now
• Stainless steel: metallic

Synthetic

• Polyglactin 910
• Polyglycolic acid
• Poliglecaprone
• Polydioxanone
• Nylon
• Polypropylene
• Polyester
• Polybutester

5. Suture size

• More zeros = finer, smaller-diameter suture
• Example: 6-0 is finer than 5-0, and 5-0 is finer than 4-0.
• A 2-0 suture is thicker and stronger than a 4-0 suture.

General principle

Typical examples

6. Suture needles

1. Point: enters tissue
2. Body: held by the needle holder
3. Swage: attached end that joins needle to the suture

Common needle points

Needle curvature

• Straight needles: accessible superficial tissue
• 1/4-circle: skin and ophthalmic work
• 3/8-circle: common for skin and superficial wounds
• 1/2-circle: deeper tissues and abdominal cavity
• 5/8-circle: deep, confined spaces such as pelvis

7. Types of suturing techniques

A. Simple interrupted suture

• Precise wound-edge alignment
• One failed stitch does not open the entire wound
• Useful for irregular, contaminated, or high-tension wounds

• Time-consuming
• More knots and more foreign material in the wound

B. Simple continuous or running suture

• Fast
• Even distribution of tension
• Uses less material

• If the suture breaks, a longer length of wound can loosen
• Less precise adjustment at individual points

C. Running locked suture

• Haemostatic closure, for example scalp wounds.

• Excessive tension can impair blood supply and cause tissue strangulation.

D. Vertical mattress suture

• Everted wound edges
• High-tension wounds
• Areas where accurate dermal approximation is needed

• Can cause ischaemia or “railroad track” scarring if tied too tightly or left too long.

E. Horizontal mattress suture

• Fragile skin
• Tension distribution
• Haemostasis

• May compromise blood flow if overly tight.

F. Deep dermal or buried dermal suture

• Reduces tension on skin edges
• Eliminates dead space
• Improves cosmetic alignment
• Supports a subsequent superficial closure

G. Subcuticular or intradermal running suture

• Clean, low-tension wounds
• Cosmetic closures
• Usually covered with adhesive strips or dressing

• Not ideal for infected, irregular, or high-tension wounds.

H. Figure-of-eight suture

• Haemostasis
• Closing small defects
• Securing tissue in selected operative situations

I. Purse-string suture

• Closure around a circular opening
• Securing drains or catheters
• Certain gastrointestinal or stoma-related procedures

Principles of proper suturing

• Obtain meticulous haemostasis and remove devitalised tissue before closure.
• Handle tissue gently to preserve blood supply.
• Approximate edges without excessive tension.
• Evert skin edges slightly, because scars tend to flatten during healing.
• Place deep absorbable sutures when needed to reduce surface tension and eliminate dead space.
• Do not overtighten sutures. Blanching, indentation, or tissue strangulation suggests excessive tension.
• Choose monofilament material when contamination or infection risk is significant.
• Use the smallest suitable suture diameter.
• Remove external sutures at the appropriate time, based on anatomical site and wound healing.

Stapler suture versus thread suture

• Stapler closure / skin staples: metal clips applied with a surgical stapler.
• Thread sutures: conventional surgical threads placed with a needle and tied as stitches.

1. Stapler closure

Advantages

• Very quick, especially for long wounds
• Simple to apply
• Useful in emergency and operating-room settings
• Avoids a needle-stick injury to the clinician
• Provides reasonable wound-edge eversion in straight wounds

Common uses

• Scalp lacerations
• Long linear surgical incisions
• Some abdominal, orthopaedic, and traumatic wounds
• Wounds where rapid closure is more important than fine cosmetic precision

Limitations and disadvantages

• Not appropriate when wound edges are irregular, crushed, jagged, or poorly aligned.
• Does not close deeper tissue layers. Deep tissue may still need absorbable thread sutures.
• Less suitable for face, fingers, feet, joints, or cosmetically sensitive areas.
• Can produce cross-hatch or “railroad track” marks if left too long.
• May be painful during removal.
• Staples should not be used on the foot because they can be uncomfortable during walking.
  Tintinalli’s Emergency Medicine: A Comprehensive Study, Wound Closure.

2. Thread sutures

Types of thread sutures

A. Absorbable thread

• Plain gut
• Chromic gut
• Polyglactin 910
• Poliglecaprone
• Polydioxanone

B. Non-absorbable thread

• Nylon
• Polypropylene
• Silk
• Polyester

Advantages

• Best method for precise edge-to-edge approximation
• Can be used in superficial and deep layers
• Suitable for irregular-shaped wounds
• Better choice for face and cosmetically important areas
• Individual interrupted stitches allow one stitch to fail without opening the whole wound
• Many material, size, and needle choices are available

Disadvantages

• Slower than stapling
• Requires more skill
• Needle-stick risk to the clinician
• More tissue handling and more knots
• Poor technique or excessive tension can cause infection, ischaemia, scarring, or wound-edge necrosis

When to choose which?

Prefer staples when:

• Wound is long, linear, and straight
• Rapid skin closure is needed
• Location is the scalp or selected surgical incision
• Fine cosmetic alignment is not the main concern

Prefer thread sutures when:

• Wound is irregular or under uneven tension
• Precise alignment is required
• The wound involves the face, lip border, eyelid, hand, or joints
• Deep layers require closure
• The wound needs a cosmetic repair

Classification of wound-closure materials/devices

1. Sutures (threads)
   • Absorbable
   • Non-absorbable
   • Monofilament or braided
   • Natural or synthetic
2. Staples
   • Skin staples: usually non-absorbable stainless-steel clips, removed after healing.
   • Internal surgical staples: may be titanium or absorbable polymer staples, used by surgical staplers for bowel, lung, or vascular procedures.
3. Other closure methods
   • Tissue adhesive/glue
   • Adhesive strips
   • Clips
   • Mesh or specialized closure devices

Stapler is not a thread suture. It is a mechanical method of wound closure. Skin staples are usually non-absorbable metallic staples used for rapid closure of long, straight skin wounds. Some internal stapling devices use absorbable polymer staples.

Wound closure methods
│
├── Sutures (thread sutures)
│   ├── Absorbable
│   └── Non-absorbable
│
├── Mechanical closure
│   ├── Staples / stapler
│   ├── Clips
│   └── Skin-closure devices
│
└── Adhesive closure
    ├── Tissue glue
    └── Adhesive strips

Comparison of sutures, staples, tissue glue, and adhesive strips

1. Sutures

Advantages

• Most versatile closure method
• Allows precise approximation of irregular wound edges
• Can close deep layers such as dermis, subcutaneous tissue, fascia, tendon, bowel, or vessels
• Best for wounds under tension and wounds requiring good cosmetic alignment
• Absorbable thread can be buried, reducing tension on the skin surface

Disadvantages

• Takes longer
• Requires technical skill and local anaesthesia in most skin wounds
• Needle-stick risk to healthcare workers
• Tight or delayed removal of skin sutures may produce stitch marks

Best examples

• Deep lacerations
• Facial wounds
• Jagged wounds
• Wounds crossing joints
• Wounds with dead space
• High-tension wounds

2. Staples

Advantages

• Very rapid for long wounds
• Strong external skin closure
• Useful for long, straight wounds, especially scalp lacerations and selected surgical incisions
• Less needle handling by the operator

Disadvantages

• Close skin only, not deep tissue
• Less precise than sutures
• Can be uncomfortable while in place and during removal
• May leave staple-track scars if retained too long
• Not appropriate for face, irregular wounds, or wounds requiring exact edge alignment

Best examples

• Long linear scalp wounds
• Selected straight surgical incisions
• Situations needing rapid skin closure

3. Tissue glue

Advantages

• Fast and painless
• Usually no needle and no suture removal
• No stitch marks
• Good cosmetic result in appropriate wounds
• Useful in children and anxious patients
• Avoids needlestick injury

Disadvantages

• Lower early tensile strength than sutures
• Cannot close deep tissue or eliminate dead space
• Not suitable for actively bleeding wounds because the glue will not adhere well
• Can break down early if exposed to moisture, friction, or tension
• More expensive than adhesive strips in many settings

Best examples

• Small, clean, straight, superficial facial wounds
• Low-tension trunk wounds
• Selected scalp lacerations
• Children who may not tolerate needle suturing or subsequent removal

Avoid tissue glue in

• Wounds under tension or across mobile joints
• Deep wounds needing layered closure
• Contaminated, infected, crushed, or bite wounds
• Jagged wounds
• Mucosal surfaces and moist areas
• Areas with dense hair unless a suitable hair-apposition technique is used

4. Adhesive strips

Advantages

• Simplest, painless, and inexpensive option
• No needle, local anaesthesia, or removal procedure usually needed
• Lowest tissue reactivity
• Can reinforce a sutured, stapled, or glued wound after closure
• Useful for children and minor superficial wounds

Disadvantages

• Weakest form of closure
• Easily loosens with sweat, water, body hair, oily skin, movement, or tension
• Cannot close deep wounds
• Poor option for bleeding, irregular, gaping, contaminated, or high-tension wounds

Best examples

• Small, clean, dry, straight wounds
• Very low-tension facial lacerations
• Reinforcement after removal of sutures or staples
• Closure of superficial skin tears in frail skin, when suitable

Quick selection guide

• Sutures = strongest and most precise
• Staples = fastest for long straight wounds
• Glue = painless for clean low-tension wounds
• Strips = cheapest and simplest for very low-tension wounds