Surgical knots have a wide variety of uses in surgery and knot tying is an essential skill for every surgeon to know and to be competent in.
A completed knot should be firm, such that slipping of the knot is nearly impossible. However, excessive tension applied through a knot can cause damage to both the suture and the tissue, which can lead to poor wound healing and tissue necrosis. Each knot should be as small as possible, as to reduce any foreign body reactions.
In this article, we shall look at the two major techniques for knot tying – the single handed tie and the tie at depth.
Single Handed Knot Tie
The square surgeons knot is the most reliable and well-known for nearly all suture materials.
Procedure
- Start with the short thread facing upwards and the long thread facing downwards
- Pick up the end of the short thread with the L thumb and ring finger, with the remainder of the thread passing over the L index and middle fingers. Pick up the end of the long thread with the R thumb and index finger
- Bring up the long thread with the R hand, to align next to the short thread
- Using the L middle finger, whilst still holding the end between L thumb and ring finger, pass the short thread under and then over the long thread
- Pull the R hand upwards and the L hand downwards, allowing the knot to rest in position; adjust the tension of the knot as necessary
- Come back upwards with the short thread, by holding the end with the L thumb and index finger. Pick up the long thread with the R thumb and index finger and bring downwards, to align next to the short thread
- Repeat the same manoeuvre as before, passing the short thread under and over the long thread
- Pull the L hand upwards and the R hand downwards, allowing the knot to rest in position; adjust the tension of the knot as necessary
- Repeat the same manoeuvre as before with the short thread facing upwards and the long thread facing downwards
- Adjust the final tension of the knot as necessary
Tying at Depth
Tying at depth is used for knot tying deep within a body cavity. It is essential the knot is tied firmly to avoid slipping, whilst upwards pressure is avoided to prevent tearing of the tissue.
Procedure
- Start with the short thread facing upwards and the long thread facing downwards
- Outside of the cavity, pick up the end of the short thread with the L thumb and ring finger, with the remainder of the thread passing over the L index and middle fingers. Pick up the end of the long thread with the R thumb and index finger
- Bring up the long thread with the R hand, to align next to the short thread
- Using the L middle finger, whilst still holding the end between L thumb and ring finger, pass the short thread under and then over the long thread
- Pull the R hand upwards and the L hand downwards
- Whilst holding tension in the long thread with the R hand outside the cavity, push the knot down with the L index finger past where the knot is needed to lie inside the cavity
- Come back upwards with the short thread, by holding the end with the L thumb and index finger. Pick up the long thread with the R thumb and index finger and bring downwards, to align next to the short thread
- Repeat the same manoeuvre as before, passing the short thread under and over the long thread
- Pull the R hand upwards and the L hand downwards
- Whilst holding tension in the long thread with the R hand outside the cavity, push the knot down with the L index finger past where the knot is needed to lie inside the cavity
- Repeat the same manoeuvre as before with the short thread facing upwards and the long thread facing downwards
- Adjust the final tension of the knot as necessary, by pushing past the knot.