How to tie dangerous surgical knots – easily. Can we avoid this?

Abstract

E H Drabble**, S Spanopoulou*, E. Sioka*, E Politaki*, I K Paraskeva*, E Palla*, L Stockley***, D Zacharoulis* (* University of Thessaly, Greece, **Clinical lead BSS course RCS England, Consultant Surgeon, University of Plymouth Hospitals NHS Trust***University of Plymouth, England) (Data statement: 'Technical appendix, statistical code, and dataset available from the Univrersity of Plymouth Data repositry Corresponding author: Eric Drabble, c/o 42 Skylark Rise, Plymouth PL6 7SN, Devon, UK ericdrabble@live.com +44 7533 186772 Abstract Objective: Secure knots are essential. Previous publications have concentrated on security of different knot types, but could individual technique be important? Determine whether the technique of formation of each layer of a surgical knot is important to the security of the knot formed. Design study: Prospective analysis of technique on knot security Materials and methods: Senior and resident surgeons, and medical students, tied knots with three techniques, using four study materials, 2/0 polyglactin 910 (vicryl), 3/0 polydioxanone (PDS), 4/0 poliglecaprone 25 (monocryl) and 1 nylon (Ethilon); a standard flat reef knot (FRK), knots tied under tension (TK), and knots laid without appropriate hand crossing (NHCK). Each knot technique was performed reproducibly, and security determined by distraction with increasing force, till each material broke, or the knot separated completely. Results: 20% of flat reef knots (FRK) tied with all suture materials slipped; all knots tied with the other two techniques, with all materials, slipped, TK (100%) and NHCK (100%). The quantitative degree of slip, was significantly less for FRK (mean 6.3% 95%CI 2.2-10.4%) than for TK (mean 312% 95%CI 280.0-344.0%) and NHCK (mean 113.0% 95%CI 94.3-131.0%). The mean lengths of suture in loops held within knots, tied under tension (TK mean 17.0mm 95%CI 16.3-17.7mm), and tied without appropriate hand crossing (NHCK mean 16.3mm 95%CI 15.9-16.7mm) were significantly lower than for flat reef knots (FRK mean 25.1mm 95%CI 24.2-26.0mm). The first two types of knot may have tightened more than anticipated, in comparison to flat reef knots, with potential undue tissue tension. Conclusion: Meticulous technique of knot tying, is essential for secure knots, appropriate tissue tension, and the security of anastomoses and haemostasis effected