title: Knot Security- How is it Affected by Suture Technique, Material, Size, and Number of Throws?
abstract: OBJECTIVE
  To measure knot security in relation to different surgical knotting techniques, suture materials, suture sizes, and number of throws commonly used in oral and maxillofacial surgery.
  
  
  METHODS
  Three surgical tying techniques were tested: square, surgeon's, and sliding knots. Suture materials included chromic gut, nylon, silk, and Vicryl (polyglycolic acid). Suture diameter sizes 3-0, 4-0, and 5-0 were tested. Ten trials were undertaken for each combination of material, size, and technique using 2, 3, 4, 5, and 6 throws (ties). Suture materials were presoaked in 0.9% saline solution for 15 minutes to simulate the environment of the oral cavity. A standard knot-tying force for each throw was applied to each combination. Knot security satisfaction was set from pilot experimental trials at less than 1.8-mm slippage from the center of the knot while testing. The dichotomous outcome of knot slippage (stable or unstable) was analyzed using logistic regression analysis and odds ratios with Tukey-adjusted 95% confidence intervals.
  
  
  RESULTS
  Knot security depended on suture technique, material, and number of throws but did not depend on suture size. In general, 4 throws were required for surgeon's and square knots, whereas 5 throws were required for sliding knots. After 5 throws, tying an additional throw did not contribute to knot security. Surgeon's knots were stronger than square knots and sliding knots (P < .0001 and P < .0001). Square knots were stronger than sliding knots (P = .01). Vicryl had the greatest knot security, followed by chromic gut, nylon, and silk.
  
  
  CONCLUSIONS
  This study showed that knot security depends on suture material, tying technique, and number of throws, but is independent of suture size. Surgeon's knot security was greater than that for square and sliding knots when using sutures commonly used in the oral cavity. Vicryl had the greatest knot security and silk had the least. For surgeon's and square knots, at least 4 throws were generally indicated to achieve knot security; for sliding knots, at least 5 throws were generally indicated. Knot security did not increase after 5 throws and 2 throws are never indicated.
authors.affiliation: Student, University of Connecticut School of Dental Medicine, University of Connecticut Health Center, Farmington, CT. Electronic address: silver@student.uchc.edu.
authors.forename: Eric
authors.initials: E
authors.lastname: Silver
authors.affiliation: Research Associate, Biostatistics Center, Connecticut Institute for Clinical and Translational Science, University of Connecticut, Farmington, CT.
authors.forename: Rong
authors.initials: R
authors.lastname: Wu
authors.affiliation: Director, Biostatistics Center, Connecticut Institute for Clinical and Translational Science, University of Connecticut, Farmington, CT.
authors.forename: James
authors.initials: J
authors.lastname: Grady
authors.affiliation: Assistant Professor, Division of Oral and Maxillofacial Surgery, Department of Craniofacial Sciences, University of Connecticut School of Dental Medicine, University of Connecticut Health Center, Farmington, CT.
authors.forename: Liansheng
authors.initials: L
authors.lastname: Song
mesh_terms: D003430:Cross-Sectional Studies; D066298:In Vitro Techniques; D008422:Materials Testing; D019647:Oral Surgical Procedures; D013536:Suture Techniques; D013537:Sutures; D013718:Tensile Strength