The purpose of this study was to determine the minimum number of throws needed for knot security for square knots using 5 common suture materials and 3 common sizes by in vitro single load to failure biomechanical testing. The hypothesis was that each suture combination studied would share a common minimum of at least 5 throws to guarantee security. Five suture materials (FiberWire [Arthrex, Inc, Naples, Florida], Monosof, Surgipro, Maxon, and Polysorb [Covidien, Mansfield, Massachusetts]) with varying suture sizes (#5, #2, 0, 2-0, and 4-0) were tied in vitro, varying the number of square knot throws (3, 4, 5, and 6). Twenty knots for each combination were statically loaded to failure in tension; whether the knot failed by fracture or slippage and the tensile strength at knot failure was determined. For the tested materials, at least 5 flat square throws should be used to confer knot security based on a binomial proportion score 95% confidence interval (CI) 0.84 to 1.0 or at least 4 throws for a 95% CI of 0.76 to 0.99. FiberWire requires 6 flat square throws per knot for security at either 95% CI level. Unless a surgeon has specific knowledge of experimental evidence that fewer throws are necessary for a specific application, the default should be a minimum of 4 throws, with 5 conferring additional security in most situations, and FiberWire requiring 6 throws.
- 1.Im JN, Kim JK, Kim HK, Lee KY, Park WH. Effect of tying conditions on the knot security of suture materials. J App Polymer Sci. 2008; 109(2):918–922.
10.1002/app.28109Crossref, Google Scholar
- 2.Dinsmore RC. Understanding surgical knot security: a proposal to standardize the literature. J Am Coll Surg. 1995; 180(6):689–699. Medline, Google Scholar
- 3.Lee AC, Fahmy RR, Hanna GB. Objective evidence for optimum knot configuration. World J Surg. 2008; 32(12):2736–2741.
10.1007/s00268-008-9764-9Crossref Medline, Google Scholar
- 4.Schubert DC, Unger JB, Mukherjee D, Perrone JF. Mechanical performance of knots using braided and monofilament absorbable sutures. Am J Obstet Gynecol. 2002; 187(6):1438–1442.
10.1067/mob.2002.129156Crossref Medline, Google Scholar
- 5.Ilahi OA, Younas SA, Ho DM, Noble PC. Security of knots tied with ethibond, fiberwire, orthocord, or ultrabraid [published online ahead of print September 30, 2008]. Am J Sports Med. 2008; 36(12):2407–2414.
10.1177/0363546508323745Crossref Medline, Google Scholar
- 6.Fong ED, Bartlett AS, Malak S, Anderson IA. Tensile strength of surgical knots in abdominal wound closure. ANZ J Surg. 2008; 78(3):164–166.
10.1111/j.1445-2197.2007.04394.xCrossref Medline, Google Scholar
- 7.Trail IA, Powell ES, Noble J. An evaluation of suture materials used in tendon surgery. J Hand Surg Br. 1989; 14(4):422–427.
10.1016/0266-7681(89)90160-5Crossref Medline, Google Scholar
- 8.Rosin E, Robinson GM. Knot security of suture materials. Vet Surg. 1989; 18(4):269–273.
10.1111/j.1532-950X.1989.tb01083.xCrossref Medline, Google Scholar
- 9.Brown RP. Knotting technique and suture materials. Br J Surg. 1992; 79(5):399–400.
10.1002/bjs.1800790507Crossref Medline, Google Scholar
- 10.Ivy JJ, Unger JB, Hurt J, Mukherjee D. The effect of number of throws on knot security with nonidentical sliding knots. Am J Obstet Gynecol. 2004; 191(5):1618–1620.
10.1016/j.ajog.2004.05.029Crossref Medline, Google Scholar
- 11.Van Rijssel EJ, Trimbos JB, Booster MH. Mechanical performance of square knots and sliding knots in surgery: a comparative study. Am J Obstet Gynecol. 1990; 162(1):93–97. Crossref Medline, Google Scholar
- 12.Trimbos JB. Security of various knots commonly used in surgical practice. Obstet Gynecol. 1984; 64(2):274–280. Medline, Google Scholar
- 13.Wüst DM, Jeyer DC, Favre P, Gerber C. Mechanical and handling properties of braided polyblend polyethylene sutures in comparison to braided polyester and monofilament polydioxanone sutures. Arthroscopy. 2006; 22(11):1146–1153.
10.1016/j.arthro.2006.06.013Crossref Medline, Google Scholar
- 14.Tera H, Aberg C. Strength of knots in surgery in relation to type of knot, type of suture material and dimension of suture thread. Acta Chir Scand. 1977; 143(2):75–83. Medline, Google Scholar
- 15.Rodeheaver GT, Beltra KA, Green CW, Biomechanical and clinical performance of a new synthetic monofilament absorbable suture. J Long Term Eff Med Implants. 1996; 6(3–4):181–198. Medline, Google Scholar
- 16.Annunziata CC, Drake DB, Woods JA, Gear AJ, Rodeheaver GT, Edlich RF. Technical consideration in knot construction. Part 1. Continuous percutaneous and dermal suture closure. J Emerg Med. 1997; 15(3):351–356.
10.1016/S0736-4679(97)00021-8Crossref Medline, Google Scholar