Sutures are sterile surgical strands or threads used to sew damaged body tissues together after an injury and repair lacerations. Once the sutures are satisfactorily placed, they must be secured with knots, which should be tightened sufficiently to approximate the wound edges without constricting the tissues or impeding blood flow.
That said, a completed knot should be firm so that it doesn’t slip. At the same time, it is worth noting that excessive tension applied through a suture knot can damage the tissue being sewed and the suture itself, potentially causing the wound to heal poorly or lead to tissue necrosis. This shows how vital suture knots are when it comes to the overall wound healing process.
In this regard, this post will discuss surgical knotting techniques and commonly used knots.
Surgical knots used in suturing
The method used to tie suture knots is fundamental when it comes to a good suturing technique. Here are the various types of knots used for different wounds.
- Square or reef knot: The square knot is the traditionally preferred knot for sewing wounds. It is formed by wrapping the suture around the needle holder once in the opposite direction between ties. Although you can tie this square knot with one hand, a two-hand square knot is recommended for most surgical works. For better firmness, use three throws.
- Surgeon or friction knot: This is a completed tension knot formed by two throws of suture around the needle holder on the initial ties and one throw on the second tie but in the opposite direction. It is best for tying synthetic absorbable nylon, polyester, and polyester fiber sutures.
- Granny knot: Granny knot is constructed by laying at least two throws on top of each other but in the same direction. Because this type of tie tends to slip when subjected to increasing pressure, surgeons usually add a third tie in the opposite direction to square it and make it firmer.
When tying suture knots, it is imperative to properly square successive throws so that the completed knots do not slip. You can achieve this by reversing the loops in successive throws so that each throw is independently and perfectly laid down parallel to the previous one. That’s why the granny knot is not recommended; it is characterized by two ties (throws) in the same direction.
Techniques for tying knots
- Single-handed technique
As the name suggests, this technique involves typing the square knot using one hand. It is recommended when sewing tissues that require little or absolutely no tension.
- Two-handed technique
Using two hands is considered the easiest and most reliable when it comes to handling and using most suture materials. As for knotting, it is a no-brainer that two hands can make a former knot than one hand.
The technique is as simple as using both hands to complete throws. Although it is used to tie most suture materials, always remember that excessive tension can hamper blood flow and constrain involved tissues.
- Tying at depth
This is a technique used to tie knots deep with a body cavity. The operator performs the suture while avoiding upward tension that might tear the tissues.
- Instrument tie
This technique is handy mainly when both ends of the suture material are short.