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04 knot tying

Latex model knot tying

02.04 Latex Model Knot tying

Knot tying – simple knot

The advantage of the “simple knot” technique shown is that you do not cross your hands while tightening the knot. This gives you greater control for gentle knot closure.You may want to use this simple knot whenever the access wound is deep or narrow and you have to keep the amplitude of your movements small.


To tie knots we recommend that you switch to a lower magnification, so a longer suture length is visible.
After passing the needle through the tissue on both sides of the cut, grasp the suture close to the needle and pull perpendicular to the cut. To prevent tearing at the tissue entry and exit points of the thread, place the opened needle holder on the tissue to provide a guidance gate for the thread, or place the convex curvature of the opened needle holder on the cut edges. Once the short suture end is close to the cut, secure it with the needle holder to keep it from slipping through while you deposit the needle. Now the needle holder can be replaced with a second forceps for greater ease and precision of handling. Grasp the long suture end with the instrument held in the opposed hand. Now position the tips of your second forceps in the “v” shape between the long and short suture ends. Moving only the instrument holding the thread, wind the thread around the other instrument’s tips two times, to make a double loop. Now your instruments are tied together and move as an entity. Move them to the short end of the thread and pick it up. Gently brush the loop off the forceps tips and over the short suture end. Now close the knot by holding the short end and pulling only the long end. Make sure to pull perfectly perpendicular to the cut. The knot is closed once both cut edges “kiss.” Approximate, do not strangulate them. Once the knot is closed, the short and long end will have switched sides.
Let go of the thread and repeat the procedure in a mirrored fashion, winding the suture around the instrument tips only once, to make a single loop. Finish with a third single loop.
A surgical knot and a half knot are now tied. If you have performed the knots correctly, both suture ends should be roughly perpendicular to the cut and can now be shortened to a safe length. This is long enough to keep the knot from nopening when it is moved, and short enough not to get the suture ends entangled while tying neighboring knots.

 

Knot tying – chopstick knot

The chopstick knot requires more dexterity since your hands are crossed while closing the knot. However, it provides more economy of movement by not having to let go of the long suture end.

Pick up the long end of the suture with either forceps at the margin of the field of sight. Place the tips of the other forceps at the designated position of the knot between the long and short suture ends. Moving only the instrument holding the long end, wind the thread around the other instrument two times, to make a double loop. Now your instruments are tied together and move as a single entity.
Move them to the short end and pick it up. Brush the loop off the instrument tips and over the short end. Now cross your instruments’ tips and close the knot by holding the short end and pulling only the long end. Once the knot is closed and the long and short ends have switched sides, do not let go of the long end.
Proceed with tying two single knots, crossing your hands to tighten each.

 

Knot tying – pitfalls, tips and tricks

Avoid pulling the thread upwards or allowing it to run through the tissue at a too narrow angle, to prevent ripping the tissue.
Do not leave the short suture end too long, otherwise it will be difficult to reach its end to tie a knot.
On the other hand, leaving the short end too short increases the risk of letting it slip through the tissue.
If you grasp too much of the long suture end, it may be hard to form loops.
Do not grasp too little of the long end either. It may be hard to form loops, or to reach the short end.
If you cannot see the suture coming out from between the forceps jaws on the nside of the forceps facing the knot the suture is more likely to slip off of your forceps.
Avoid placing the forceps on which you want to make loops outside the “v”, otherwise you will not tie a secure surgical or half-knot.
Not exchanging the long and short suture ends, also results in a knot that is not tied accurately.
When tightening knots, be careful not to pull too strongly. Remember: “approximate, do not strangulate,” in order to prevent vessel wall damage.
Try not to pull oblique to the suture line when closing knots. You may end up with the cut suture ends projecting into the anastomosis.
A knot with very short suture ends may open when moved. Long suture ends, on the other hand, may get in your way while tying subsequent knots.
If the cut edges are subject to stretch and cannot be approximated by the first knot, first pull on the short end until the cut edges touch, then tighten the knot by bulling on the long end.
You can create this scenario by placing the pins in the latex glove a little further apart.

 

Knot tying – Self-evaluation

Try to perform a series of accurate simple knots. Once your stitches have a symmetric bite, are perpendicular to the cut and parallel to each other, the distances between them are equally large and the knots closed accurately with their suture ends pointing away from the suture line, you can proceed to the next exercise.