Knot tying is an important skill for any surgical or procedure-oriented rotation. We will briefly review some of the basics of knot tying in this article. For a playlist of videos you can watch on knot tying, visit our YouTube page!
Ways to tie a knot:
Two-handed tie. This is the basic starting point. Using both hands to tie a surgical knot helps you learn and understand how to tie strong square Important features to pay attention to are: laying the first throw all the way down to the tissue before starting the next throw, holding equal tension on both strands, and passing the free strand through each loop in alternating directions with each successive throw.
One-handed tie. This is a more advanced way of tying knots and can also be more efficient. One hand will constantly hold one strand, while the other hand will be used to form all of the alternating loops and throws. The same important features should be paid attention to.
Instrument tie. You will most often be doing the instrument tie when you are the one suturing. You will hold one strand with your non-instrumented hand, loop the strand around your held instrument, and then grab the free strand with your instrument before pulling both strands tight. Remember to alternate directions with each throw in order to make square knots (see below).
General Principles of Knots
Knot Security vs. Loop Security
You want your knot to stay tight and not unravel. The knot will stay tight with more friction between the strands – this is referred to as knot security. You maximize friction by tying square knots with each throw (i.e., alternating directions with each throw) and pulling tight, equal tension after each throw. Then, with each successive throw, make sure you lay the knot down as close to the tissue (or previous throw) as possible with as little twisting of the suture as possible. In this way, you maximize loop security to prevent unraveling.
One way of preventing slippage while tying the first throw is by passing the suture through the first loop twice before locking (i.e., tightening) it – this is referred to as a surgeon’s knot. This is generally used when tying under tension to prevent slippage of that first throw. The disadvantage of using a surgeon’s knot is it uses excess suture material in the wound.
Square Knot vs. Slip Knot
As stated earlier, the square knot is done by alternating the direction of each successive throw and maximizes friction. Additionally, by laying down each throw squarely, the minimum amount of suture material is used for the knot. A square knot done well will only require four (alternating) throws to achieve optimal tightness.
When two, or more, successive throws are done in the same direction, there is less friction - resulting in a slip knot. This enables you to further tighten, or slip the knot tighter, but the knot can also more easily unravel or loosen on its own. A slip knot should always be completed with four square throws to keep optimal knot security.
Ways to improve your knot tying
Practice is the only way to improve your knot tying. One can easily practice often in your free time, using sutures, shoelaces, ropes, or anything available with strands.
Always concentrate on holding each strand firmly with equal tension, but don’t overpull.
Often, one finds that when alternating directions with the one-hand tie (or the two-hand tie), there is one direction that is manually harder to throw than the other direction. Understand your weakness and be sure to concentrate more on that direction.
Don’t try to tie as fast as an Attending Surgeon. Speed comes with repetition. Practice on your proficiency, and your speed will naturally improve.
Do you remember first learning how to tie your shoelaces as a child? By now as an adult, you can probably tie your laces without thinking too much about it. By understanding these principles of knot tying, you have a better foundation on how to practice your manual skills. As your proficiency improves, you will be able to tie knots during procedures without thinking too much.