Secure vascular pedicle ligation is a fundamental skill required for surgeons to safely perform a vast number of invasive procedures.1 Despite the increasing availability of vessel-sealing devices able to consistently achieve hemostasis for surgeries such as ovariectomy,2 castration, and splenectomy,3 the importance of being able to properly secure hemostatic knots cannot be understated. Currently, vascular pedicle ligation remains the most commonly performed hemostatic technique used in a general practice setting where, because of cost limitations, vessel-sealing devices may not be practical.4 Hemorrhage has been reported as a cause of death in dogs undergoing ovariohysterectomy,5 splenectomy,6 liver lobectomy,7 and limb amputation.8 The reported incidence of intraoperative bleeding following ovariohysterectomy at various teaching hospitals ranges from 4% to 9%,9–11 but an incident rate as high as 79% has been reported for dogs weighing > 22.7 kg.10 A greater frequency of intraoperative bleeding in this subset of dogs could be explained by latent bleeding attributable to a lack of securing and maintaining a tight first throw as subsequent square knot overthrows are placed.1,4 After large pedicles are compressed with the first throw, expansion of the crushed tissue can unintentionally loosen the first throw before the second throw of a square knot locks the first throw in place.1 This can produce a loose pedicle ligature that can allow substantial postoperative hemorrhage. It is imperative that the first throw remains tight when ligating a pedicle until subsequent throws are placed to secure the knot. In recent in vitro studies1,4 of knots tied with monofilament and multifilament suture material on a variety of vascular pedicle models, it was shown that a single surgeon's throw is not reliable as a first throw on large vascular pedicles. Compared with other friction knots, the first throws of surgeon's knots have been shown to loosen and readily leak at pressures well below physiologic arterial pressure.1,4
In the human and veterinary medical literature,12–16 there is no consensus on which type of suture material is best used for pedicle ligation. Some investigators have found that monofilament suture may perform better than multifilament suture,12 whereas others have reported the opposite result.13,14 The use of various types of suture material has theoretical advantages and disadvantages, with multifilament suture having greater pliability but also more tissue drag and higher capillarity that may lead to an increased risk of bacterial colonization of the suture.15 On the other hand, because of their greater memory and lower coefficient of friction, monofilament sutures may compromise knot security, especially when a large gauge is chosen.16
The purpose of the study reported here was to compare the in vitro security of 4 different friction knots used as a first throw in the creation of a ligature with a variety of monofilament and multifilament suture types. We hypothesized that there would be a significant difference in knot security achieved with the 4 friction knots, but that knot security would not differ among suture types for each knot investigated.
Sutures for the study were donated by Covidien. Funding sources had no involvement in the study design, data analysis and interpretation, or writing and publication of the manuscript.
The authors thank Dr. Maxime Lorange for technical assistance.
Ashley modification of the Miller knot
CRE Single-Use Fixed Wire Balloon Dilator, Boston Scientific, Natick, Mass.
Top Fin silicone airline tubing, PetSmart Inc, Phoenix, Ariz.
Maxon, Covidien, Mansfield, Mass.
PDS II, Ethicon, Cincinnati, Ohio.
Monocryl, Ethicon, Cincinnati, Ohio.
Biosyn, Covidien, Mansfield, Mass.
Sofsilk, Covidien, Mansfield, Mass.
Polysorb, Covidien, Mansfield, Mass.
Vicryl, Ethicon, Cincinnati, Ohio.
REI Compact Digital Scale, REI, Sumner, Wash.
Pump 22, Harvard Apparatus, Holliston, Mass.
Mikro-Tip catheter pressure transducer, Millar Inc, Houston, Tex.
CardioSOFT Pro, Sonometrics Corp, London, ON, Canada.
SAS, version 9.4, SAS Institute Inc, Cary, NC.
1. Leitch BJ, Bray JP, Kim NJ, et al. Pedicle ligation in ovariohysterectomy: an in vitro study of ligation techniques. J Small Anim Pract 2012;53:592–598.
2. Schwarzkopf I, Van Goethem B, Vandekerckhove PM, et al. Vessel sealing versus suture ligation for canine ovarian pedicle haemostasis: a randomised clinical trial. Vet Rec 2015;176:125.
3. Monarski CJ, Jaffe MH, Kass PH. Decreased surgical time with a vessel sealing device versus a surgical stapler in performance of canine splenectomy. J Am Anim Hosp Assoc 2014;50:42–45.
4. Hazenfield KM, Smeak DD. In vitro holding security of six friction knots used as a first throw in the creation of a vascular ligation. J Am Vet Med Assoc 2014;245:571–577.
6. Richter M. Spleen. In: Tobias KM, Johnston SA, eds. Small animal veterinary surgery. Vol 2. St Louis: Saunders-Elsevier, 2012;1351.
7. Mayhew PD, Weiss C. Liver and biliary system. In: Tobias KM, Johnston SA, eds. Small animal veterinary surgery. Vol 2. St Louis: Saunders-Elsevier, 2012;1607.
8. Seguin B, Weigle JP. Amputations. In: Tobias KM, Johnston SA, eds. Small animal veterinary surgery. St Louis: Saunders-Elsevier, 2012;1036.
9. Burrow R, Batchelor D, Cripps P. Complications observed during and after ovariohysterectomy of 142 bitches at a veterinary teaching hospital. Vet Rec 2005;157:829–833.
11. Berzon JL. Complications of elective ovariohysterectomies in the dog and cat at a teaching institution: clinical review of 853 cases. Vet Surg 1979;8:89–91.
12. Gandini M, Giusto G, Comino F, et al. Parallel alternating sliding knots are effective for ligation of mesenteric arteries during resection and anastomosis of the equine jejunum. BMC Vet Res 2014;10(suppl 1):S10.
13. Silver E, Wu R, Grady J, et al. Knot security—how is it affected by suture technique, material, size, and number of throws? J Oral Maxillofac Surg 2016;74:1304–1312.
14. Trimbos JB, Van Rijssel EJ, Klopper PJ. Performance of sliding knots in monofilament and multifilament suture material. Obstet Gynecol 1986;68:425–430.
15. Schmeidt C. Suture material, tissue staplers, ligation devices, and closure methods. In: Tobias KM, Johnston SA, eds. Small animal veterinary surgery. Vol 1. 2nd ed. St Louis: Saunders-Elsevier, 2018;688–731.
16. Huber DJ, Egger EL, James SP. The effect of knotting method on the structural properties of large diameter nonabsorbable monofilament sutures. Vet Surg 1999;28:260–267.
17. Haskins SC. Monitoring anesthetized patients. In: Grimm KA, Lamont LA, Tranquilli WJ, et al, eds. Veterinary anesthesia and analgesia: the fifth edition of Lumb and Jones. Ames, Iowa: Wiley, 2015;86–113.
18. Müller DA, Snedeker JG, Meyer DC. Two-month longitudinal study of mechanical properties of absorbable sutures used in orthopedic surgery. J Orthop Surg Res 2016;11:111.
19. Avoine X, Lussier B, Brailovski V, et al. Evaluation of the effect of 4 types of knots on the mechanical properties of 4 types of suture material used in small animal practice. Can J Vet Res 2016;80:162–170.
20. Giusto G, Comino F, Vercelli C, et al. Evaluation of various hemostatic knot configurations performed by veterinary students. J Am Vet Med Assoc 2018;253:219–224.
21. Schaaf O, Glyde M, Day RE. In vitro comparison of secure Aberdeen and square knots with plasma- and fat-coated polydioxanone. Vet Surg 2010;39:553–560.
22. Field EJ, Hebert S, Friend EJ, et al. A survey of current practices and influences on the choice of suture material, pattern and size used in commonly performed procedures in UK small animal veterinary practice. Vet Rec Open 2017;4:e000189.
23. Kummerle JM. Suture material and patterns, tissue adhesives, staples, and ligating clips. In: Auer J, Stick J, eds. Equine surgery. 4th ed. St Louis: Elsevier, 2012;181–202.