Sutures

Question 1

Define a suture

Answer 1

A suture is a strand of material used to tie (ligate) blood vessels and to sew (approximate) tissues together.

Question 2

Characteristics of Sutures

Answer 2

Memory – inherent ability to return to or maintain its original gross shape.

Knot strength – amount of force necessary to cause a knot to slip.

Elasticity – measure of ability to regain original form & length after deformation

Tensile strength – measure of ability to resist deformation & breakage.

Breaking strength – limit of tensile strength @ which suture failure occurs.

Capillarity – extent to which absorbed fluid is transferred along suture.

Plasticity – measure of ability to deform without breaking & to maintain new form after relief of deforming force.

Pliability – ease of handling & ability to adjust tension/secure knots.

Question 2

What are the Ideal Qualities of a suture?

Answer 2

1. It should not shrink in the tissues.
2. It should have and maintain adequate tensile strength until its purpose is served.
3. It should stimulate minimal tissue reaction.
4. It should not create a situation suitable for bacterial growth.
5. It should be non-electrolytic, non-capillary non-allergenic, non-carcinogenic and non-thrombogenic in vascular surgery.
6. It should be inexpensive and easily sterilised.
7. The material should handle comfortably and naturally by the surgeon and a knot should hold securely without fraying or cutting.
8. No effect on wound tensile strength

Question 3

Classification of sutures

Answer 3

• Absorbable/Non-absorbable.
• Natural/Synthetic
• Mono/Multifilament

Question 3

What are absorbable sutures?

Answer 3

A sterile strand prepared from collagen derived from healthy mammals or a synthetic polymer. It can be treated to modify its resistance to absorption. It can be coated with a suitable antimicrobial or coloured by a colour additive as approved by FDA.

Question 3

What are the types of absorbable sutures ?

Answer 3

Natural collagen
Synthetic

Question 4

Examples of natural collagen sutures:

Answer 4

Surgical gut
Collagen sutures
Biological absorbable sutures

Question 4

What is a surgical gut suture, what are the types and how long does it last?

Answer 4

Derived from submucosa of sheep intestine or serosa of beef intestine. It could be plain or chromic when treated with chromium salt. After 28 days chromic catgut loses 60% of its tensile strength while plain loses it between 7-14 days.

Question 4

What are collagen sutures?

Answer 4

Its extracted from a homogenous dispersion of pure collagen fibres from flexor tendons of beef.

Question 4

What are Biological absorbable sutures?

Answer 4

Its of historical interest e.g. preserved skin, fascia lata strips, cadaveric dura mater, and kangaroo tendon.

Question 4

What are the types of synthetic absorbable suture?
And how long does it take for each to be absorbed?

Answer 4

1. Polyglycolic (dexon) and polyglactic acid; They are homopolymers of glycolide and copolymer lactide respectively. Absorption is complete within 4 months (120 days )
2. Polyglactin 910 (vicryl); B-copolymer of lactide and glycolide absorbed within 90 days. Dexon looses tensile strength more rapidly than vicryl but absorbed more slowly.
3. Poly Dioxanone Synthetic (PDS) smooth sutures; It’s monofilament with total absorption at 180 days thus providing longer wound support.

Maxon (polyglyconate) artificial monofilament; polymer of glycolic acid and trimethylene carbonate, available undyed or coloured green to enhance visibility. Suture absorption starts at 60 days and completes by 6months (180 days).

Question 4

What are examples of NATURAL NON-ABSORBABLE SUTURES?

Answer 4

1. Surgical silk; Derived from raw silk spun by the silk worm larva in construction of its cocoon. Its processed to remove waxes and gums, twisted or braided together to form a suture strand. Its treated to render it serum-proof.

Looses its tensile strength after 1 year and never found after 2 years. It is dyed black for easy visibility in tissues. Unlike cotton it looses its tensile strength on exposure to moisture.

2. Dermal suture; Twisted silk fibres encased in a non absorbable coating of tanned gelatin or other protein substance.
3. Virgin silk; Consist of several natural silk filaments drawn and twisted together to form a fragile strand.
4. Surgical cotton; It gains tensile strength when wet.
5. Linen; Cellulose material made from twisted long staple flax fibres.
6. Horsehair and human hair: Have been used for plastic and nerve repair.

Question 4

What are NON-ABSORBABLE SUTURES?

Answer 4

These are strands of material that effectively resist enzymatic digestion in living tissue.

It could be mono- or multifilament of metal or organic fibres rendered into a strand by spinning, twisting or braiding.

It could be naturally coloured or dyed with FDA approved dye stuff.

It may be coated or uncoated, treated or untreated for capillarity designated Type A or Type B.

Question 5

What are examples of SYNTHETIC NON-ABSORBABLE SUTURES?

Answer 5

Surgical stainless steel wire; Made from soft annealed iron alloy formula( with nickel, chromium and molybdenum) presenting optimum metal purity, strength, flexibility, uniformity and compatibility with stainless steel implants and prosthesis.
Its disadvantages are difficult handling, late fragmentation and the possibility of cutting tissues.

Nylon (ethilon); Polyamide polymer derived by chemical synthesis. It has a high tensile strength and moderate tissue reaction. It degrades in-vitro at 15% per year (monofilament).

Polyester fibre (Mersilene: Ethiflex); Polymer of terephthalic acid and glycoethylene (multifilament braided).

Polypropylene

Dacron, Teflon and orlon.

Question 6

What are the dimensions of sutures?

Answer 6

British pharmacopoeia system : 10/0 – 5

Metric system : Suture diameter varies from 0.02 – 0.8mm which corresponds to 0.2 – 0.8(mm x 10) on metric system.

Question 7

What is the anatomy of a needle and types of each part?

Answer 7

Point - tip to max cross section of body
Types: Cutting, Round bodied, Taper

Body - majority of needle length Types: straight, Half Curved, Compound curved.

Swage - suture attachment end Types: Channel, Drill, Non swage (traumatic)

Question 8

What type of suture needle would you require for a:
1) Ureter/bowel repair
2) Skin/fascia repair

Answer 8

1) round-body suture
2) cutting

Question 9

What are the Principles of suturing
(what is Jenken’s rule)

Answer 9

1. Curved needle should enter the skin so that its tip is perpendicular to skin
2. Take a large wound in 2 bites
3. Jenken’s rule ; 0.5cm from wound edge for both entry and exit and 1cm between each stitch (zone of lysis), length of the suture should be4x the wound length
4. Stitch should not be too loose or too tight (being too tight can cause ischemia and necrosis)
5. Deep wound closure should be in more than one layer
6. For long wounds better to start with a central suture; divide wound into 2 & possibly 2 further sutures half way on each side
7. If there is tension better to close from alt. ends
8. Symmetry in distance b/w stitches
   All stitch should be of similar tension
   Knot should be placed on one side

Question 10

What are the uses of a suture?

Answer 10

Ligate
Wound closure
Transfix
Stay suture
Repair
Follow thru
Purse string
Retraction
Tagging of tissues following hand injury, resection

Question 10

What are the complications of sutures?

Answer 10

Tissue rxn
Keloid
Hypertrophic scar
Implantation cyst
Wound infection
Stitch abscess, sinus & marks

Question 10

What are the current trends?

Answer 10

• Tissue Clips e.g. Michel clips
• Adhesive tapes e.g. opsite, Tegaderm & Bioclusive, steristrips
• Tissue glue e.g. cyanoacrylate & fibrin
• Staples