Ideal suture characteristics
The choice of suture material influences wound healing. Ideal suture characteristics include;
- good knot security
- adequate tensile strength
- flexibility and ease of handling
- inertness and non-allergenic nature
- resistance to infection
- smooth passage through tissue
- absorbability, when desirable
Surgeons should choose sutures that they are comfortable with, and that are suited to the intended application specially in laparoscopy because we dont have tactile feedback. This choice should be based on the duration of tensile strength. For internal sutures, the least number of knots as possible should be used to avoid foreign body volume overload, to ensure knot security and to avoid an excessive knot burden and consequent foreign body reaction.
Type of suture
Sutures traditionally have been classified into natural (ie naturally occurring), and synthetic (man made). The use of natural sutures is declining, for a number of reasons. Examples of natural sutures include catgut and silk. Suture material is also classified into absorbable and non-absorbable.
Absorbable sutures
The natural absorbables (catgut) tend to have unpredictable rates of absorption and tissue reaction. For the most part, these sutures have short half-lives, so they are not good for wound closure where strength is desirable. Their use is being discontinued.
The synthetic absorbables are broken down by hydrolyzation. They generally have a longer half-life, less tissue reaction, and a more consistent breakdown rate. The synthetic absorbables, polyglycolic acid (Dexon®) or polyglactin 910 (Vicryl®), have decreased tissue reaction compared to the natural absorbables. Knot security is fair. Polyglactin 910 (Vicryl) keeps 75% of its tensile strength for about 2 weeks and 50% by 3 weeks. The coated sutures decrease the drag through tissue, so it is easier to use, but there are variable rates of absorption.
Poliglecaprone 25 (Monocryl®) is a monofilament product that has easy passage through tissue, good handling, and is inert. It keeps tensile strength for only a week, but stays in the wound for almost 4 months. It is good for anastomoses, gynecologic work, and small vessel ligation and epithelial approximation.
The delayed absorbable monofilament sutures such as polydioxanone (PDS®) and polyglyconate (Maxon®), used for abdominal wound closure have good tensile strength and low tissue reaction, but the knots are not as strong. Polydioxanone (PDS) is also good for contaminated fields because it has a low affinity for bacteria. It is good for general use, tissue approximation, biliary work, anastomoses, fascial closures, heart surgery, and orthopaedics. Panacryl® is a braided synthetic absorbable suture. It has good tensile strength, low tissue reaction, and fairly good knot security. It maintains 60% of its tensile strength at 6 months. It may be a good substitute for a nonabsorbable suture because it has complete absorption in 2� years. It is good for fascial closures, closing tissues under tension, and it might have a role in the compromised patient where you presume there is going to be inadequate or delayed wound healing. Non-absorbable sutures
The natural nonabsorbables, cotton and silk, should be relegated to the past. Even though they have good knot security, and are easy to tie, they provoke a lot of tissue reaction.
Synthetic nonabsorbable sutures in common use include nylon, polyester and stainless steel.
Suture Size The narrower the suture, the lower its tensile strength. Narrower sutures cause less scarring. In addition a narrower suture will harbour fewer bactreria.
Surgeons should use the smallest suture that they are comfortable with and that will give optimal security of wound closure, with minimal wound tension.
For skin closure, 2/0 to 6/0 may be used depending on the anatomical site of the wound. For facial wounds, a fine suture is required, and it should be removed early. Layered closure may be required. Usually, 2/0 or 3/0 is used elsewhere, with the exception of the hand, where 4/0 may be preferred.
Needle
Detachable or integral
Curved or straight
Cutting or atraumatic Knots The knot is the most important part of the suture closure n vivo, the knot is the determining factor in suture strength in 95% of sutures tested. Complex knots have twice the security of simple knots.
However, increasing complexity of the knot simply leads to the suture strength being the weak link. The size of the knot is also important. If you use the same suture and increase from 3 to 5 throws, the foreign body volume is increased by 50%.
Suturing techniques
Interupted
Simple
Vertical mattress
Donati
Figure of eight
Continuous
Simple
Vertical mattress
Locking
Subcuticular Whichever method is selected, the principle is to achieve secure water tight wound closure, without tension.
Laparoscopic suturing
why surgeons are reluctant to knot?
- Time taking
- Lack of confidence
- Interrupted practice
- Improper selection of knot type
- Improper techniques of knotting
- Difficult hand eye coordination
- Long cylindrical instruments
- Two dimensional vision
- Poor ergonomics
Types of Laparoscopic knot
- Extracorporeal
- Roeder's knot
- Meltzer's knot
- Tayside knot
- Tumble Square knot
- Intracorporeal
- Surgeons knot
- Square knot
- Tumble Square Knot
- Dundee jamming knot
- Aberdeen termination
Suture Material
- For small tubular structure & small blood vessels dry chromic catgut
- For Intracorporeal continuous or interrupted suturing Vicryl
- For Interrupted suturing in the repair of hernia, Fundoplication & rectopexy Dacron (polyester) or silk.
Syaeges of Knot tying
- Configuration (Tying)
- Shaping (Drawing)
- Securing (Locking or snuggling)
Patient information
We should tell the patient what type of suture has been used, and if it requires removal over external wound, when this should be done. Remember that absorbable suture material outwith the tissues, will not be absorbed!
Summary
It is important to remember that knot is either exactly right or is hopelessly wrong, It is never nearly right.
