Flat square knots: are 3 throws enough?

Abstract

The objective of the study was to determine the integrity of flat square knots. Three sutures were used in both 0 and 2-0 suture gauges: poliglecaprone 25 (Monocryl), polyglactin 910 (Vicryl), and silk. For each, flat square knots were tied with either 3 or 5 throws. Knots were tested to failure. The major outcome measured was the proportion of 3 throw knots untying, compared with that of 5 throw knots. There were high rates of untying for the poliglecaprone 25 and for the polyglactin 910 with both suture gauges when tied with only 3 throws. The failure rate decreased significantly when the throws were increased. There was no statistical benefit to increasing the number of throws for silk. Knot failure is decreased by increasing the number of throws for poliglecaprone 25 and polyglactin 910. However, there is no advantage to increasing the number of throws from 3 to 5 for silk.