Laparoscopic knot strength: a comparison with conventional knots

Objective: To compare the strength of laparoscopic knots with those used at laparotomy. Methods: Three types of laparoscopic knots commonly used (Roeder, extracorporeal sliding square, and intracorporeal two-turn flat square) and three widely used conventional knots (flat square, surgeon's square, and sliding square) were tied using seven suture materials. Each knot was tied five times in random order by a single surgeon in a pelvic training model. Knot strengths were scored by tensiometer readings. A two-way analysis of variance was performed to uncover differences in mean knot strength. Tukey multiple-comparisons test was performed to determine the variability in strength of different knot geometries. Knot strength was measured in newtons. Results: Significant main effects for knot geometry (P < .05) and material (P < .05) as they contribute to differences in knot strength were identified, as well as an interaction for knot geometry with material (P < .05). The laparoscopic Roeder knot was significantly weaker than all other laparoscopic and conventional knots tested. The laparoscopic extracorporeal sliding square knot was significantly weaker than the conventional surgeon's square knot, and the conventional sliding square knot was significantly weaker than the conventional flat square knot and the surgeon's knot. The laparoscopic intracorporeal two-turn flat square knot was as strong as the strongest conventional knot. A significant main effect was discovered for knots with eight throws. Conclusion: When performing laparoscopic procedures that result in significant tension on suture lines, consideration should be given to using the stronger laparoscopic knots, such as the intracorporeal two-turn flat square knot and the extracorporeal sliding square knot, instead of the weaker Roeder knot.