Core Surgical Skills ...

Indications

Some surgeons opt to place a surgeon's knot when wound edges are not well apposed. Under these circumstances, mild wound tension causes the first throw of the intended knot to pull apart before it is locked in with a second square throw. The additional friction created from the double suture pass of a surgeon's knot helps to keep the stitch at the appropriate intrinsic suture tension until the second throw locks the knot in place. Otherwise, if tension causes unwanted tissue loosening after the first throw is placed, and the second throw locks the knot in place, the stitch might be too loose to allow apposition of the edges. When this occurs, the stitch must be replaced.

Precautions

Surgeon's knots take slightly longer to tie than conventional square knots. More importantly, the knots are larger, which can increase suture-induced inflammation and separate tissue planes. Therefore, surgeon’s knots should not be used routinely and are not recommended when tissue edges are tension-free and remain in apposition after the first square throw is completed.

A surgeon's knot is also contraindicated when tying chromic catgut suture, because increased friction between the double-wrapped strands tends to fray and significantly weaken the suture material and the knot.

In general, it is advisable to avoid a surgeon's knot during pedicle ligation, because the only practical method to determine if a ligature is tight on a thick pedicle (such as a fat filled ovarian pedicle where the suture becomes buried as it is tightened and the knot is no longer exposed) is to "feel" that there is no more "give" in the suture when tensioning the strands, indicating that the first throw is sufficiently tight. However, when a surgeon's throw is used on a pedicle, as the throw is being "snugged down", the friction in the double twisted throw might "lock" the throw prematurely, and it might "feel" as if it is tightly applied when, in fact, it is not. This is particularly true when using multifilament suture material. This problem can lead to fatal hemorrhage after surgery.

Special Considerations

Notice that when a surgeon’s double twist throw is completed and the second square throw is tightened, the first throw bunches up, and the enclosed suture loop becomes tighter than the original formed loop. In other words, the intrinsic suture tension increases when the second throw is fully tightened. This tightening is not from the first throw slipping down, but rather from the "bunching up" of the double twist on the first throw. It is important to keep this in mind when using a surgeon's knot, particularly during skin suturing when the skin edges are under some tension. To address this problem, the surgeon must intentionally pull the surgeon's throw down incompletely, anticipating that the second throw will pull the tissue closer together (further tightening the intrinsic suture tension) as the double twisted throw tightens the loop during tensioning of the second throw. Otherwise, the surgeon will unintentionally create skin stitches with excessive intrinsic suture tension.