To hold a wound together in good apposition until such time as the natural healing process is sufficiently well established to make the support from the suture material unnecessary and redundant.

Contents at a Glance

  1. Sutures
  2. Needles
  3. Anatomy of a Needle
  4. Needle Points
  5. Needle Features

Suture Characteristics

Sutures

Introduction

Sutures, or stitches, are materials used to close a wound. They are used in an attempt to improve and speed healing. Pulling the edges of a wound together and stitching help in healing process. Sutures are used to close cuts from injuries or surgery. They are commonly used on the skin, internal tissues, organs, and blood vessels.

Purposes:
- approximating tissues
- ligating blood vessels
- transfixing

Needles

Suture needles

a) Curvature: Straight needle, Curved 2/8 of circle, Curved 3/8 of circle (preferred needle in most cases), Curved 4/8 of circle, Curved 5/8 of circle

b) Needle Tip: Tapered (used in vascular sutures), Conventional cutting needle, Reverse cutting needle (preferred in most cases)

Anatomy of a Needle

Suture needles

POINT

This portion of the needle extends from the tip to the maximum cross-section of the body.

BODY

This part of the needle incorporates most of the needle length. The body of the needle is important for interaction with the needle holder and the ability to transmit the penetrating force to the point. The needle factors that affect this interaction include needle diameter and radius, body geometry, and stainless steel alloy. These components determine the needle-bending moment, ultimate moment, surgical-yield moment, and needle ductility.

SWAGE

The suture attachment end creates a single, continuous unit of suture and needle. The swage may be designed to permit easy release of the needle and suture material (pop-off).

- Channel swage: A needle is created with a channel into which the suture is introduced, and the channel is crimped over the suture to secure it into place. The diameter of the channel swage is greater than the diameter of the needle body.
- Drill swage: Material is removed from the needle end (sometimes with a laser), and the needle is crimped over the suture. The diameter of the drill swage is less than the diameter of the needle body.
- Nonswaged: Alternatively, the suture may be passed through an eye, similar to that found in a sewing needle. In a closed-eye configuration, the shape may be round, oblong, or square. In a French (split or spring) eye, a slit is in the end of the needle with ridges that catch and hold the suture in place.
Several disadvantages are associated with the use of a nonswaged needle. Tissue passage of a double strand of suture leads to more tissue trauma. In a swaged needle, the suture is less likely to become unthreaded prematurely. Also, decreased handling helps maintain suture integrity. Swaged sutures are not subject to suture fraying or damage due to sharp corners in the eye of eyed needles.

COATING

The needle may be coated with silicone to permit easier tissue passage. The coating helps reduce the force needed to make initial tissue penetration and the frictional forces as the body of the needle passes through the tissue.

Needle Points

Suture needles

 

a) Taper: This type of needle penetrates and passes through tissues by stretching without cutting. A sharp tip at the point flattens to an oval/rectangular shape. The sharpness is determined by taper ratio (8-12:1) and tip angle (20-35°). The needle is sharper if it has a higher taper ratio and lower tip angle. The taper-point needle is used for easily penetrated tissues (eg, subcutaneous layers, dura, peritoneum, abdominal viscera) and minimizes potential tearing of fascia. Sharp gradually tapered needles guarantees easy penetration in every bite. Available in heavy diameter too!

b) Conventional: This type of needle has 3 cutting edges (triangular cross-section that changes to a flattened body). The third cutting edge is on the inner, concave curvature (surface-seeking). It had 3 sidesAccurately sharpened, easily cuts through dense, thick & irregular tissues

c) Reverse Cutting: The third cutting edge is on the outer convex curvature of the needle (depth-seeking). These needles are stronger than conventional cutting needles and have a reduced risk of cutting out tissue. The needles are designed for tissue that is tough to penetrate (eg, skin, tendon sheaths, oral mucosa). Reverse-cutting needles are also beneficial in cosmetic and ophthalmic surgery, causing minimal trauma. It had accurately sharpened 3 sides, easily cuts through dense, thick & difficult to penetrate tissues.

d) Taper Cutting: Designed to cut through dense & tough tissues without damaging the surrounding tissues with easy passage.

e) Blunt: This type of needle dissects friable tissue rather than cuts it. The point is rounded and blunt, ideal for suturing the liver and kidneys. Blunt nosed to dissect friable tissues

Needle Features

Suture needles

- suture needle made from special stainless steel alloy. Malleable & ductile needle-provides high resistance to bending & breaking.

- all suture needles are drilled end, giving least tissue trauma as the suture & needles are seamlessly fused.

- needles finished in an inert atmosphere give smooth mirror finish for easy passge through tissues

- ribbed suture needle for better grip in needle holder, adds to penetration power

- precisely drilled needle offers high suture-needles hold strength & trouble free suturing

- sharp gradually tapered needle profile quarantees easy penetration in every bite

- special geometry of sharpened triangular sides of cutting needles along with sharpened tip penetrates through tissue with ease

- range of types of needles include round body (tapered point), taper cutting, cutting, reverse cutting, blunt & trocar point

Suture Characteristics

Sutures

a) Tensile Strength: Related to suture size. Related to weight required to break a suture
b) Knot strength: Force required for a knot to slip
c) Configuration: Monofilament (less risk of infection), Braided multifilament (easier to handle and tie)
d) Elasticity: Degree suture stretches and return to original length
e) Memory or suture stiffness: High memory: Suture stiff, difficult handling, unties
f) Tissue reactivity (inflammatory response to suture): Reaction peaks in first 2 to 7 days

Choice of suture

Types of Sutures

Depends on:
1. Properties of suture material
2. Absorption rate
3. Handling characteristics and knotting properties
4. Size of suture
5. Type of needle

Suture types

Types of sutures

 

A. Natural and synthetic
- Natural: catgut and silk
- Synthetic: Polyglactin 910, Polyglycolic acid, Polydioxanone (PDS), Polypropylene, Polyester, Polyamide, Linen

B. Absorbable and Non-absorbable
- Absorbable:
a) Advantages: Broken down by body and no foreign body left
b) Disadvantages: Time of wound support
b) Ex. catgut, Polyglactin 910, Polyglycolic acid, Polydioxanone (PDS)

- Non-absorbable:
a) Advantages: Permanent wound support
b) Disadvantages: foreign body left, suture sinus and suture extrusion
c) silk, Nylon, Polypropylene, Polyester, Polyamide, Linen

C. Monofilament and Braided
- Monofilament
a) Advantages: Smooth surface, low friction, less drag, less tissue trauma, less tissue infection, no capillarity
b) Disadvantages: handling and knotting and stretch ability and bending - pliability
c) Ex. Polyglactin 910, Catgut, Glyconate, Polydioxanone (PDS), Polypropylene, Polyamide

- Braided
a) Advantages: Better strength, soft and pliable and good handling
b) Disadvantages: Capillary action, tissue trauma, tissue drag, tissue cutting and harboring bacteria
c) Ex. Polyglactin 910, Polyglycolic acid, Polyester, Silk

Absorbable Suture

 

Types of sutures

 

Polyglactin 910 - synthetic
- Brand name: Vicryl
- Structure: Braided and monfilament
- Colour: violet or undyed
- Tensile strength: retention of 65% knot tensile strength after 14 days; 40% at 21 days; 10% at 35 days
- Absorption reaction: hydrolysis & low inflammatory tissue response
- Mass absorption: complete mass absorption in 60 to 90 days
- Common application: gastrointestinal, O&G, ophthalmic, orthopedics, urology surgeries, skin closure (intra/subcutaneous)

Polyglycolic acid (coated with glyconate) - synthetic
- Brand name: Safil@Violet
- Structure: Braided
- Colour: violet or undyed
- Tensile strength: retention of 50% knot tensile strength after 18 days
- Absorption reaction: hydrolysis & low inflammatory tissue response
- Mass absorption: complete mass absorption in 60 to 90 days
- Common application: gastrointestinal, O&G, ophthalmic, orthopedics, urology surgeries, skin closure (intra/subcutaneous), neurosurgery and ligature

Polyglycolic acid (coated with magnesium stearate) - synthetic
- Brand name: Safil@Quick
- Structure: Braided
- Colour: green or undyed
- Tensile strength: retention of 50% knot tensile strength after 7 days
- Absorption reaction: hydrolysis & low inflammatory tissue response
- Mass absorption: complete mass absorption in around 42 days
- Common application: O&G (episiotomy), ophthalmic (conjunctival suturing), oral mucosa, pediatrics, skin closure (intra/subcutaneous) and ligature. *When 10 days of soft tissue approximation is sufficient.

Natural gut (purified collagen 98% from bovine serosa or ovine intestinal submucosal fibrous layer) - natural
- Brand name: Catgut (Plain and Chromic) *The chromic gut contains a chromic salt solution to delay absorption
- Structure: monofilament
- Colour: natural brown
- Tensile strength: retention of 50% knot tensile strength after 6 days (plain catgut); after14 days (chromic catgut)
- Absorption reaction: proteolysis & high inflammatory tissue response
- Mass absorption: complete mass absorption in 60 (plain) to 90 (chromic) days
- Common application: gastrointestinal, O&G and orthopedics,

Glyconate (uncoated)
- Brand name: Monosyn
- Structure: monofilament
- Colour: violet or undyed
- Tensile strength: retention of 50% knot tensile strength after 14 days
- Mass absorption: complete mass absorption in 60 to 90 days
- Common application: gastrointestinal, O&G, urology, plastic and reconstructive surgeries, skin closure (intra/subcutaneous) and ligature

Polydioxanone (uncoated)
- Brand name: Monoplus
- Structure: monofilament
- Colour: violet
- Tensile strength: retention of 50% knot tensile strength after 28-35 days
- Mass absorption: complete mass absorption in 180 to 210 days
- Common application: abdominal wall closure, orthopedics and pediatric cadiovascular surgery

 

Non-absorbable Suture

 

Types of sutures

 

Polypropylene (uncoated) - synthetic
- Brand name: Premilene
- Structure: monofilament
- Colour: blur
- Mass absorption: non-absorbable
- Common application: vascular, cardiac, plastic and reconstructive, skin closure, neurosurgery, microsurgery, gastrointestinal surgeries

Polyester (coatedwith silicone) - synthetic
- Brand name: PremiCron
- Structure: braided
- Colour: green or white
- Mass absorption: non-absorbable
- Common application: cardiac and orthopedics

Polyamide (uncoated) - synthetic
- Brand name: Dafilon
- Structure: monofilament
- Colour: blue, black or undyed
- Tensile strength: permanent
- Mass absorption: degrades at a rate of 15-20% peryear
- Common application: plastic and reconstructive, skin closure, neurosurgery, microsurgery, ophthalmic surgeries

Silk (Natural silk filaments coated with wax and silicone/uncoated) - synthetic
- Brand name: Silkam (coated) and Virgin silk (uncoated)
- Structure: Braided (Slikam) and Twisted (Virgin Silk)
- Colour: black (Silkam) and blue (Virgin Silk)
- Tensile strength: gradual loss over time (about one year)
- Mass absorption: non-absobable
- Common application: general, skin closure, oral surgeries, neurosurgery and ligature

Stainless steel alloy (uncoated) - synthetic
- Brand name: Steelex
- Structure: twisted and monofilament
- Colour: metallic
- Tensile strength: permanent
- Mass absorption: non-absorbable
- Common application: orthopedics

Linen (coated with silicone and polyvinyl solution) - synthetic
- Brand name: Linatrix
- Structure: twisted
- Colour: natural white
- Tensile strength: retention of 50% initial tensile strengthafter 6 months. After 2 years, 30-40% of initial tensile strength
- Mass absorption: very long term absorption
- Common application: gastrointestinal surgery and ligature

 

Suture Size

a) General
- Superficial facial lesions: 6-0 nylon
- Other superficial skin lesions: Low skin tension areas: 5-0 nylon, Higher skin tension areas: 4-0 nylon

b) Annotation for suture size indications below
- Skin: Superficial monofilament Nonabsorbable Suture
- Deep: Dermal Absorbable Sutures

c) Size O: Largest suture

d) Size 2-O

e) Size 3-O
- Skin: Foot
- Deep: Chest, Abdomen, Back

f) Size 4-O
- Skin: Scalp, Chest, Abdomen, Foot, Extremity
- Deep: Scalp, Extremity, Foot

g) Size 5-O
- Skin: Scalp, Brow, Oral, Chest, Abdomen, Hand, Penis
- Deep: Brow, Nose, Lip, Face, Hand

h) Size 6-O: Skin: Ear, Lid, Brow, Nose, Lip, Face, Penis

i) Size 7-O: Smallest Suture: Skin: Eyelid, Lip, Face

Suture indications by location

Usage

 

a) Scalp, Torso (chest, back, abdomen), Extremities
- Superficial Nonabsorbable Suture: 4-O or 5-O
- Deep Absorbable Suture: 3-O or 4-O

b) Face, Eyebrow, Nose, Lip
- Superficial Nonabsorbable Suture: 6-O
- Deep Absorbable Suture: 5-O

c) Ear, Eyelid
- Superficial Nonabsorbable Suture: 6-O

d) Hand
- Superficial Nonabsorbable Suture: 5-O
- Deep Absorbable Suture: 5-O

e) Foot or sole
- Superficial Nonabsorbable Suture: 3-O or 4-O
- Deep Absorbable Suture: 4-O

f) Penis
- Superficial Nonabsorbable Suture: 5-O or 6-O

Suture removal timing

Scalp: 6-8 days
Face, Eyelid, Eyebrow, Nose, Lip: 3-5 days. Follow with papertape or steristrips
Ear: 10-14 days
Chest and abdomen: 8-10 days
Back: 12-14 days
Extremities: 12-14 days
Hand: 10-14 days
Foot and sole: 12-14 days
Penis: 8-10 days
Condition delaying wound healing: 14 to 21 days
- Chronic Corticosteroid use
- Diabetes Mellitus

Common errors of suture use

1. Too many throws. Increases foreign body size. Causes stitch abscesses
2. Intra-cuticular rather than subcuticular sutures causing hypertrophic scars
3. Holding monofilament sutures with instruments reduces tensile strength by over 50%
4. Holding butt of needle causes needle and suture br