Towards a better laparoscopic knot: using knot quality scores to evaluate three laparoscopic knot-tying techniques

In the past, knot-tying techniques have been evaluated and compared, but there has been a scarcity of objective scoring systems in these comparison studies. Using an objective scoring system, we aimed to compare 3 types of knots: intracorporeal flat-square knots, intracorporeal slip-square knots, and extracorporeal square-knots for their Knot Quality Scores (KQS) and their rates of slippage.

Three surgeons tied 100 knots in the 3 knot categories. The knots tied were evenly distributed amongst the 3 surgeons with each surgeon contributing at least 30 knots. These knots were tied in a nonrandomized fashion. Forces were measured using a tensiometer and an objective scoring system, the Knot Quality Score (KQS), which is used to compare the knot's strength and rates of slippage.

Median KQS scores of the 3 groups were not all the same. The median KQS and variance for the extracorporeal square knot group was 0.32 and 0.0079, respectively. For the intracorporeal slip-square knot group, the median KQS and variance was 0.28 and 0.00017, respectively. Lastly, for the intracorporeal flat-square knot group, the median KQS and variance was 0.33 and 0.0075, respectively. Follow-up analysis revealed that the KQS medians (0.32 versus 0.28) of the extracorporeal square-knots and intracorporeal slip-square knot groups were significantly different (P<0.0001). The medians of the intracorporeal slip-knot and intracorporeal flat-square knot groups (0.28 versus 0.33) were also statistically significantly different (P<0.0001). There was no statistically significant difference in KQS scores between extracorporeal square-knots and intracorporeal flat-square knots.

Extracorporeal square-knots and intracorporeal flat-square knots can tolerate better distraction forces and thus have higher median KQS scores compared with intracorporeal slip-square knots.