Surgeons and sutures, and surgery and sutures go together; and there is no suture without knots!
The knots that we apply during the surgical procedures should have the following characteristics:
- The knot should be secure
- The knot should not become loose and slip
- It should be easily applied
- It should stay long
- One should be able to apply the knot with any type of sutures.
These characteristics are met by only one knot—The Reef knot — It is rightly called the secure knot or the square knot.
The knots are required to secure a bleeding point or for approximation of tissues or wound edges. Thus, a reef knot is a universal requirement. Every surgeon should have a good grasp of the technique of correctly applying the knot. This is a very basic requirement because the commonest complication of any surgical procedure is “the slipping of the knot!”
HOW TO APPLY THE REEF KNOT?
This knot can be applied:
- By single hand technique – left or right
- By both hands
- With instrument
- At the depths:
All these can be learnt with a “knot tying board”.
One Hand Technique Using the Left Hand
Place the short end of the thread below the band (bridge) away from you. Pick up the tip of the thread by the left hand holding it with the middle finger and the thumb, while the index finger stretches the thread (Figs 1.1 and 1.2).
The long end of the thread is carried by the right hand to form an “open” loop, i.e. there should be no twist in the loop like a figure of “8” (Fig. 1.3).
If a reef knot is applied with a “figure of 8” (Fig. 1.12) loop, at the last stage of “snugging” the knot, it will never sit tightly because the figure “8” will “untwist.” This leads to an insecure knot and it is sure to slip. This will never happen if the loop is an “open” one.
“Index finger looping stage”
Once the loop is formed, the left index finger passes through the loop under the thread held by the right hand and rides over the the end held by the left hand and pulls it through the loop to be held by the index and the middle fingers (Fig. 1.4).
Now the left hand moves towards the surgeon and the right hand holding the opposite end of the thread, moves away from the surgeon in a horizontal plane; thus one should note the hands cross each other. If the hands do not cross at each throw, it will not result in the reef knot. After the completion of the first throw the knot is snugged down (Fig. 1.5).
“The middle finger looping”
Now the thread carried on the left hand is held at its tip by the index finger and the thumb, while the palm is facing downwards. The right hand now brings the (longer) other end of the thread to form an “open loop”; at this stage the left hand is turned upwards (Fig. 1.6). Now the middle finger passes through the loop below the end held by the right hand and over rides the end held in the left hand to pull it through the loop (Fig.1.7).
As the thread is pulled through the loop, the tip is held between the middle and the ring finger and the left hand carrying it moves away from the surgeon, while the right hand holding the opposite end moves towards the surgeon.
At the end of the movement, the knot is snugged down over the first knot.
One will find a beautiful “Reef knot” – otherwise a square knot resulting (Fig. 1.8). This square knot does not/ will not slip or loosen. The essential feature is the hands should cross each other every time to effectively produce a reef knot.
The above description is about application of the reef knot with the left hand; one can easily transfer the method/ technique to the right hand without any difficulty.
The Surgeon's Knot
The main difference here is that there are two throws at every step, thereby the knot is made more secure. When major blood vessels, pedicles, slippery structures are secured, these knots are very useful, since seldom they slip.
A single throw is first applied either using a one handed or two handed technique. Another throw in the same fashion (Fig. 1.9) is placed and the ends are pulled to tighten the knot.
A fresh throw is placed in the same manner, but not tightened. One more similar throw is fashioned resulting in a double throw as before (Fig. 1.10).
Now the throw is tightened to complete the surgeon's knot (Fig. 1.11).
Here also the hands should cross each other at every step; the thread is held horizontally.
Without the hands crossing, one cannot apply a reef knot.
The surgeon's knot may not look pretty but it is a very secure knot.
Errors while Knotting
- At every step of applying the reef knot, the hands should cross; the mistake done is after the index finger looping, the left hand moves to its original place away from the surgeon.
- Index finger looping and middle finger looping will not help, if the hands do not cross – this will result in a “slip knot”, this will lead to ligature slipping.
- Instead of the open loop, if the loop is a crossed one, it will result in an insecure knot (figure of “8” loop) (Fig. 1.12).
- The long end of the thread is held vertically – even if the finger looping alternates, it results in a “slip knot”
Hence, for proper reef knot:
- Hands should cross at every step.
- The thread should be held horizontally.
- It must be snugged down properly.
- The wastage of suture material is reduced.
- In inconvenient and deeper levels (e.g. cystic duct and artery, pelvic surgery, etc.) this technique is very helpful.
- Always develop the habit of holding the tip of the thread by the tip of the instrument; if the thread is held in the middle by the jaws, it “fractures” the thread and by chance the knot sits at that point of weakness, it is likely to snap; hence this caution.
A straight artery forceps is used for this purpose for ease; one can use a curved forceps also.
After taking the thread around the point of business, e.g. a bleeding point, the long end is looped around the instrument by rotating the instrument in a “clockwise direction” (Fig. 1.13). The tip catches and picks up the tip of the short end and is pulled through the loop to complete the first throw and snugged down (Fig. 1.14).
Now the long end of the thread is looped around the instrument by rotating the instrument in “the anti-clockwise direction and the tip of the short end is picked up by the instrument to be pulled through the loop to complete the second throw.
Here also the hands should cross each other alternatively; only then a square knot results.
Knot Tying At Depth
This type of knot application becomes necessary, while working at the depth, e.g. pelvis, cholecystectomy, etc. One has to be careful in such situations, so that the reef knot is securely applied. The basic feature is, the knot is made outside the wound and is carried down by the right index finger and the left hand tightens the knot; the right index finger pushing the knot down can “feel” the knot getting tightened. The role of the hands can change depending on the situation or the convenience of the surgeon.
- The thread is taken around the object to be ligated, either by the hand or a haemostat.
- The first throw for the reef knot is made outside the wound (Fig. 1.17).
- The knot is pushed down to the depth by the right index finger (Fig. 1.18).
- The left hand holding the other end tenses the strand against the index finger.
- The knot should go to the tissue and not the tissue to the knot. The tissue to be ligated should not move or levered out.
- Repeat another throw at the surface and complete the reef knot (Fig. 1.19).
- This is also snugged down after being pushed by the right index finger.
Two Hand Techniques
One end of the thread is passed around the structure to be tied and held by the left hand in the palm such that the thread passes over the left index finger (Fig. 1.20).
The other end is grasped by the right hand and is carried between the extended left thumb and the index finger (Fig. 1.21). The index finger passed through the loop thus formed to emerge on the left side along with the thumb.
Now the thread carried by the right hand is grasped between the thumb and the index finger of the left hand (Fig. 1.22) and is passed through the loop again (Fig. 1.22).
The emerging thread is held by the right hand (Fig. 1.23) and moves away from the surgeon as the left hand moves towards the surgeon (Fig. 1.24) the result: the first throw is snugged down as a knot.
The thread held by the left hand is passed around the extended thumb (Fig. 1.25) encircling it.
The right hand carries the thread to form a loop, when the left index finger overrides it and goes through the loop. The thread in the right hand is now held by the left index finger and the thumb to carry it through the loop (Figs 1.26 and 1.27). The emerging thread is held by the right hand and moves towards the surgeon as the left hand moves away from the surgeon (Fig. 1.28).
Fig. 1.25: The thumb encircled by the thread held by the left hand and the index overriding the thread of the right hand
As the throw snugged down, a nice looking reef knot results (Fig. 1.28). One should practice these knotting techniques to gain mastery.
Whether one hand or two hand technique is practiced, one can appreciate these methods result in the wastage of suture materials. To reduce this, the same “secure knot” can be applied with an instrument.