How are knots tied to secure suture placement?

Updated: Mar 05, 2020
  • Author: Desiree Ratner, MD; Chief Editor: Dirk M Elston, MD  more...
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Answer

Once the suture is satisfactorily placed, it must be secured with a knot. [42] The instrument tie is used most commonly in cutaneous surgery. The square knot is traditionally used.

First, the tip of the needle holder is rotated clockwise around the long end of the suture for two complete turns (see the image below). The tip of the needle holder is used to grasp the short end of the suture. The short end of the suture is pulled through the loops of the long end by crossing the hands, so that the two ends of the suture are on opposite sides of the suture line. The needle holder is rotated counterclockwise once around the long end of the suture. The short end is then grasped with the needle holder tip and pulled through the loop again.

Knot tying. Knot tying.

The suture should be tightened sufficiently to approximate the wound edges without constricting the tissue. Sometimes, leaving a small loop of suture after the second throw is helpful. This reserve loop allows the stitch to expand slightly and is helpful in preventing the strangulation of tissue because the tension exerted on the suture increases with increased wound edema. Depending on the surgeon’s preference, one or two additional throws may be added.

Properly squaring successive ties is important. In other words, each tie must be laid down perfectly parallel to the previous tie. This procedure is important in preventing the creation of a granny knot, which tends to slip and is inherently weaker than a properly squared knot. When the desired number of throws is completed, the suture material may be cut (if interrupted stitches are used), or the next suture may be placed.


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