Tissue Approximation Techniques in Laparoscopic Surgery - Dr. R.K. Mishra

Laparoscopic Tissue Approximation Techniques

Knots are used since the time of primitive man for trapping animals and making weapons. Today’s laparoscopic knots are basically a modification of knots used by Seamen, Fishermen, Weavers, or Hangmen. In much of the literature on laparoscopic surgery, the learning curve for performing the technique is described as steep. In fact, laparoscopy is more than a new technique; it is a completely different way of operating as far as tissue approximation is concerned. The visualization is different, the instruments are different, and the tactile aspects are very different. Laparoscopic suturing and knotting is a skill that requires a great deal of practice: “As a young surgeon in training, you sit up all night, night after night, tying knots over and over and over again until you become perfect”.

There are many ways of laparoscopic tissue approximation but most commonly used one are:

•    Laparoscopic extracorporeal and intracorporeal knots
•    Surgical glues which act as a tissue adhesive
•    Laparoscopic clips
•    Laparoscopic staplers
•    Laser welding.

Laparoscopic Suturing and Knotting

It is important to remember that knot is either exactly right or is hopelessly wrong, and never nearly right.

There are three steps of knot tying:

1.    Configuration (Tying)
2.    Shaping (Drawing)
3.    Securing (Locking or snuggling).

Choice of Suture Material

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 nonallergenic nature
•    Resistance to infection
•    Smooth passage through tissue
•    Absorbability, when desirable.

Surgeons should choose sutures that they are comfortable with, and that is suited to the intended application. This choice should be based on the duration of tensile strength. For internal sutures, the least number of knots should be used, to ensure knot security and avoid an excessive knot burden and consequent foreign body reaction.

Types of Sutures

Sutures traditionally have been classified into natural (i.e. naturally occurring), and synthetic (man-made). The use of natural sutures is declining, for a number of reasons like tissue reaction, infection, weak knots. Examples of natural sutures include catgut and silk. The suture material is also classified into absorbable and nonabsorbable.

Absorbable Sutures

The natural absorbable (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 absorbable are broken down by hydrolyzation. They generally have a longer half-life, less tissue reaction, and a more consistent breakdown rate. The synthetic absorbable, polyglycolic acid (Dexon® ) or polyglactin 910 (Vicryl®), have decreased tissue reaction compared to the natural absorbable. Knot security is fair and can be used for extracorporeal knotting.
Polyglactin 910 (Vicryl) keeps 75 percent of its tensile strength for about 2 weeks and 50 percent by 3 weeks. The coated sutures decrease the drag through tissue, so it is easier to use, but there are variable rates of absorption. Polyglactin is good suture material for intracorporeal suturing.

Poliglecaprone 25 (Monocryl®) is a monofilament product that has an 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 anastomosis, gynecologic work, and small vessel ligation, and epithelial approximation. This material can be used for both extra and intracorporeal suturing.
The delayed absorbable monofilament sutures such as polydioxanone (PDS®) and polyglycolide (Maxon®), used for abdominal wound closure have good tensile strength and low tissue reaction, but the knots are not as strong. PDS is considered as the ideal material for extracorporeal knotting by many surgeons and gynecologists.

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, anastomosis, fascial closures, heart surgery, and orthopedics. Panacryl® is a braided synthetic absorbable suture. It has good tensile strength, low tissue reaction, and fairly good knot security. It maintains 60 percent of its tensile strength at 6 months. It may be a good substitute for a non-absorbable suture because it has complete absorption in 2½ 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.

Nonabsorbable Sutures

The natural nonabsorbable, 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. The role of this material in laparoscopic surgery is very limited and can be used if the other materials are not available.

Suture Size

The narrower the suture, the lower is its tensile strength. Narrower sutures cause less scarring. In addition, a narrower suture will harbor fewer bacteria. Surgeons should use the smallest suture that they are comfortable with and that will give optimal security of wound closure, with minimal wound tension. Usually, 2/0 or 3/0 is used in most of the minimal access surgical procedures, with the exception of the fallopian tube, where 6/0 may be preferred.

Knots

The knot is the most important part of the suture closure in vivo, the knot is the determining factor in suture strength in 95 percent of sutures tested. Complex knots have twice the security of simple knots. However, the 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 percent.

Laparoscopic Needle

In general surgery, needles are either straight or curved. With increasing proficiency, the curved needle can also be used but in laparoscopic surgery, the most intuitive needle is endoski needle. Endoski has the advantage of both straight and curved needle.

Endoski Needle

The distal end is a tapered half circle and the proximal shaft of the needle is straight. The shaft of the needle is 1.5 times the length of the curved portion of endoski needle. In our day to day practice, we can convert half circled needle into endoski shaped by making proximal half of the needle straight.

Endoski needle
  Endoski needle

Laparoscopic Suture Material

Although it is a personal preference and varies surgeon to surgeon considering a handicap of laparoscopic setting following is recommended.

•    For extracorporeal suturing of small tubular structure like cystic duct and small blood vessels: dry chromic catgut.
•    For extracorporeal suturing of thick tubular structure like the appendix and large blood vessels: PDS.
•    For intracorporeal continuous or interrupted suturing: Vicryl.
•    For intracorporeal interrupted suturing in the repair of hernia, Fundoplication, and rectopexy: Dacron (polyester) or silk.

Types of Laparoscopic Surgical Knots

•    Extracorporeal (Tied outside the body and then slipped inside using a push rod)
–    Roeder's knot
–    Meltzer's knot
–    Tayside knot.

•    Intracorporeal (tied with the help of needle holder within the body cavity)
–    Square knot
–    Surgeons knot
–    Tumble square knot
–    Dundee jamming knot
–    Aberdeen termination.

A long length of the ligature is required (90 cm) for extracorporeal suturing. It must be long enough to have the knot pusher threaded on to it, to be passed into the abdomen, around the structure to be ligated, and to be brought out again and still have sufficient length for the surgeon to tie his/her knot effectively. The type of extracorporeal knot chosen to complete the loop depends on the clinical situation and the material used.
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