What is the Best Surgeon's Knot? Evaluation of the Security of the Different Laparoscopic Knot Combinations

To investigate the security of various knot combinations in laparoscopic surgery.

Prospective nonrandomized trial (Canadian Task Force classification II).

Storz Training Centre, Sao Paulo, Brazil.

Different knot combinations (n = 2000) were performed in a laparoscopic trainer. Dry or wet 2.0 polyglycolic acid or dry 2-0 poliglecaprone 25 was used. The tails were cut at 10 mm, and the loops were tested in a dynamometer. The primary endpoints were the forces at which the knot combination opened or at which the suture broke. Resulting tail lengths were measured.

Surprisingly, the combination of a 2-throw half knot (H2) and a symmetric 1-throw half knot (H1s) (a surgical flat knot) opened at <1 Newton (N) in 2.5% of tests and at <10 N in 5% of tests. This occasional opening at low forces persisted after 1 or 2 additional H1s knots. A sequence of an H2 or a 3-throw half knot (H3) followed by a H2, either symmetric or asymmetric (H2H2 or H3H2), resulted in 100% secure knots that never opened at forces below 30 N. Other safe combinations were H2H1s followed by 2 blocking half hitches, and a sequence of 5 half hitches with 3 blocking sequences.

A traditional surgical knot (H2H1s) occasionally opens with little force and thus is potentially dangerous. Safe knots are H2H2 and H3H2 combinations, a sequence of 5 half hitches with 3 blocking sequences, and H2H1s together with 2 blocking half hitches.