Knot Tying: Two-handed Tie

 

The two-handed tie is the fundamental skill of all of general surgery. While many trainees gravitate to the one-handed tie due to increased speed, the two-handed tie allows much better control of tension across the knot. It is also much easier to tie a square knot using two hands, which increases knot security.

The goal of knot tying is “approximation not strangulation.” In other words, the knot should be tightly enough such that the knot will not slip and that tissue is brought together snugly, but not so tight that the tissue is rendered ischemic which can lead to wound breakdown. Remember that tissue will likely continue to swell after the wound is closed.

When practicing knot-tying, it is helpful to start by using rope or string, and then work towards larger sutures and eventually smaller sutures. Once you have reached automaticity you should be able to reliably tie a square knot without slippage and without looking at your hands. At this point you should practice while wearing gloves, tying in a narrow cavity, and/or tying under increased tension.

Notes on Square knot vs Granny knot:

Square knots are inherently more secure than granny knots (or sliding knots). Square knots fail by breakage due to limitations in the strength of the suture, while granny knots are more likely to fail due to slippage or unravelling. Some surgeons choose to use slip knots or granny knots intentionally in certain circumstances, but you should make this decision intentionally based on the amount of tension across the knot and the relative importance of knot security. When tying a granny knot intentionally, it can be helpful to add additional throws to the knot to compensate for increased slippage.

Two-handed Square Knot:

Common Errors:

Granny knot:

Failure to Cross

Inadequate tension:

Surgeon’s Knot

The Surgeon’s Knot is a variation of the square knot, where the initial throw is brought through the loop twice instead of once. This increases friction of the 1st throw and resists the wound pulling apart while the knot is being tied. This is often helpful when the wound is on some tension, and many surgeons routinely perform a surgeon’s knot in most clinical scenarios.

Surgeon’s Knot Common Error:

Self Assessment

 

Expert Assessment: