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

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

DESIGN: Prospective nonrandomized trial (Canadian Task Force classification II).

SETTING: Storz Training Centre, Sao Paulo, Brazil.

INTERVENTION: 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.

MEASUREMENTS AND MAIN RESULTS: 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.

CONCLUSION: 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.