Ceazon Edwards, MD, Kristina Shaffer, MD, Amy Somerset, MD, Rose Callahan, MS, Kathryn Ziegler, MD. Beaumont Health System
Introduction: Knot security is the ability of knots to resist slippage as force is applied, and the optimal number of throws to ensure a secure knot improves efficiency and outcome. The literature on the accepted number of throws per type of suture material has been largely anecdotal, often referring to 3 throws for silk, 4 for polyglactin 910 (Vicryl), five for polydioxanone(PDS), and six for polyproprolene (Prolene). We report a pilot knot-tying study of four suture types to determine optimal numbers of throws.
Materials and Methods: Four senior general surgery residents (PGY-5 and above) and four attending surgeons participated. Participants viewed a standardized instructional video and a one-handed knot-tying tutorial. They were instructed to tie one-handed knots, beginning each knot with two throws in the same direction, and square the third and subsequent throws in the opposite direction. Each surgeon tied 64 knots, using differenttypes of 2-0 suture material: silk, polyglactin, polydioxanone, and polyproprolene. Suture types were evaluated using 3, 4, 5,or 6 throws. The participants were randomized to both suture type and order of throw numbers. The knots were then tested on the F.A.S.T knot tester (Sawbones, Vashon Island, WA) for slippage (insecure knot) or breakage (secure knot). Generalized estimating equation (GEE) analysis was used to determine optimal throw number.
Results: 512 knots were individually tested on the knot tester for slippage and recorded as % slipped (see table). The percentage of slipped knots varied by participant and ranged from 5% to 67%. Generalized estimating equation analysis suggested that the only significant variable when determining knot security was number of throws (p=0.02), not suture type or participant training level. The optimal number of throws for 2-0 silk, polydioxanone, and polypropylene was five, whereas six throws was optimal for polyglactin.
Conclusion: Knot security is dependent on the number of throws placed, and these optimal numbers were higher in our study than the commonly accepted number of throws.
| Type | Throws | % Slipped |
| Silk | 3 | 59 |
| 4 | 38 | |
| 5 | 22 | |
| 6 | 25 | |
| Vicryl | 3 | 81 |
| 4 | 63 | |
| 5 | 41 | |
| 6 | 38 | |
| PDS | 3 | 53 |
| 4 | 34 | |
| 5 | 22 | |
| 6 | 31 | |
| Prolene | 3 | 47 |
| 4 | 38 | |
| 5 | 9 | |
| 6 | 19 |
Presented at the SAGES 2017 Annual Meeting in Houston, TX.
Abstract ID: 88470
Program Number: P326
Presentation Session: iPoster Session (Non CME)
Presentation Type: Poster