Tensile strength of a surgeon’s or a square knot

Abstract

Objective—To test the integrity of surgeon’s knots and flat square knots using four different suture materials. Study Design—Chromic catgut, polyglactin 910, silk, and polydioxanone sutures were tied in the two types of knot configurations. For all sutures, a 0-gauge United States Pharmacopeia suture was used. Knots were tied by a single investigator (JB). Suture was soaked in 0.9 % sodium chloride for 60 seconds and subsequently transferred to a tensiometer where the tails were cut to 3 mm length. We compared the knots, measuring knot strength using a tensiometer until the sutures broke or untied. Results—A total of 119 knots were tied. We found no difference in mean tension at failure between a surgeon’s knot (79.7 Newtons) and a flat square knot (82.9 Newtons). Using a Chisquare test, we did not find a statistically significant difference in the likelihood of knots coming untied between surgeon’s knots (29%) and flat square knots (38%). Conclusions—Under laboratory conditions, surgeon’s knots and flat square knots did not differ in tension at failure or likelihood of untying.