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SURGICAL KNOTS

Knots

  • Defined as an intentional complication in cordage which may be useful or decorative

  • Key skill for all surgeons to produce strong well-tied knots in an efficient manner

    • Used in suturing, ligation of tubular structures, securing drains, etc​

    • Easily hundreds of knots required in every surgical procedure​​

  • General principles:​

    • The completed knot must be firm, so that slipping is virtually impossible

    • The knot must be as small as possible to prevent an excessive amount of tissue reaction when absorbable sutures are used, or to minimize foreign body reaction to nonabsorbable sutures. Ends should be cut as short as possible.

    • In tying any knot, friction between strands ("sawing") must be avoided as this can weaken the integrity of the suture.

    • Care should be taken to avoid damage to the suture material when handling. Avoid the crushing or crimping application of surgical instruments, such as needleholders and forceps, to the strand except when grasping the free end of the suture during an instrument tie

    • Excessive tension applied by the surgeon will cause breaking of the suture and may cut tissue. Practice in avoiding excessive tension leads to successful use of finer gauge materials.

    • Sutures used for approximation should not be tied too tightly, because this may contribute to tissue strangulation.

    • The surgeon should not hesitate to change stance or position in relation to the patient in order to place a knot securely and flat

Knots

One-handed reef knot

  • Consists of two throws, the coming down and going throw, performed alternately

  • Coming down throw:

    • Pick up the short end between the thumb and ring finger​

    • Turn the hand palm upwards so that the thread passes downwards over your straightened index and middle fingers

    • Separate thumb and ring finger from the middle and index fingers

    • With right hand, hold the long end of the thread and pass it over the left middle and index fingers, creating a loop in the thread

    • Flex the left middle finger under the short end and then straighten the finger so that the short end is on the back of the middle finger, and grip the short end between the middle and index fingers

    • The thread can now be grasped between the middle and index fingers, and released by the left ring finger and thumb and drawn through the loop with the middle and index fingers

    • Carefully lay the knot square and is snugged down, ensuring not to let go of the suture with either hand

    • The hands have crossed in the process

  • Going up throw:

    • From where you left off, grasp the short end in the left hand between the thumb and index finger​

    • Keep the left hand palm upwards so that the short end is passing upwards over your fingers towards the thumb and index finger, and now separate them from the remaining fingers

    • The right hand comes down towards you and stays there

    • Catch the end of the short thread on the back of the left middle finger by flexing it and straighten it so that the thread can be gripped between the left middle and ring fingers

    • Release the thread from the left thumb and index finger, and pull the short end through the loop

    • Lay it down carefully so that the going up short end goes on up and the hands have crossed

    • Snug it down to see the typical figure of eight of a reef knot

The surgeon's knot

  • To increase the friction in the first throw, tie a double throw first, followed by a single throw

  • Standard method:

    • Begin in the same way as the coming down throw of the single-handed knot with your left hand, but hold the long end that is in your right hand as if about to perform a going up throw

    • Separate the left middle and ring fingers

    • Form a loop by moving the right hand away over the left middle and ring fingers so that the left index and middle fingers pass through the loop as usual

    • Then pass the right middle, ring and little fingers through the same loop with the palm upwards above the left index finger

    • Bend both middle fingers under their respective ends for the thread and then straighten them so that the thread is on the back of each middle finger

    • Draw the short end through the loop towards the left using the left index and middle fingers, and at the same time take the long end through the loop towards the right using the middle and ring fingers of the right hand

    • Ensure the throw lies correctly by moving the left short end towards and the right long end away from you

    • Snug the knot down, then perform the standard going up throw

    • This method cannot be performed if there is an instrument in the right hand and be careful if there is a needle on the long end

  • Single-handed surgeon's knot

    • Start off the same way as for a simple coming down throw​

    • Take the short end between left thumb and ring and little fingers, and have it coming down over the left middle and index fingers

    • Hold it over the wound and separate the left ring and index fingers from the other two

    • Hold the long thread in your right hand and pass it up over the left middle and index fingers twice to make two loops

    • Bend the left middle finger, grip the short end between the index and middle fingers and pull the thread through both loops at once

    • Snug the knot down, then perform the standard going up throw

One-handed reef knot
The surgeon's knot

The instrument tie

  • Reef knot:

    • Place the instrument (usually a needle holder) over the thread, with the short end farthest away from you

    • Loop the long end of the thread up and around the instrument

    • Grasp the short end of the thread within the jaws of the instrument

    • Complete the first throw by pulling the short end down towards you and crossing your hands

    • Place the instrument over the thread again, with the short end closest to you and form a loop over the instrument

    • Grasp the short end within the jaws of the instrument

    • Pull through and cross the hands again

  • Surgeons knot:

    • Start as for a simple reef knot, but form a double loop in the first throw​

    • This is followed by a standard single-loop second throw

The instrumet tie

Tying at depth

  • With haemostat (artery clip), pass the thread around the structure that requires ligation

  • If performing the coming down throw first, make the throw above the cavity with your left hand and lead it down into the pot with your left index finger

  • Snug the throw by applying tension with the right hand vertically upwards and the left index finger vertically downwards

  • Then do the going up throw outside the cavity and lead the throw down into the pot with your right index finger

  • Complete the knot with another coming down throw

  • Surgeon's knot is commonly employed when tying at depth to avoid loosening of the first throw

Tying at depth
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