A mechanical study of ligature security of commercially available pre-tied ligatures versus hand tied ligatures for use in equine laparoscopy.
Authors: Carpenter Elaine M, Hendrickson Dean A, James Susan, Franke Chad, Frisbie David, Trostle Steven, Wilson David
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Hand-Tied Ligatures in Equine Laparoscopic Surgery When performing minimally invasive abdominal surgery in horses, surgeons frequently rely on commercially available pre-tied ligature loops (Endoloops) to secure vessels and ligaments, yet these products carry significant cost implications. Carpenter and colleagues mechanically tested multiple hand-tied knot configurations using different suture materials and sizes to identify whether a cost-effective alternative could match the security of standard square knots, using a materials testing machine to measure load-to-failure across 20 repetitions of each combination. Remarkably, only the 4S modified Roeder knot tied in size 2 polydioxanone approached acceptable security levels, achieving 103 N breaking strength compared with 157 N for square knots; all other hand-tied configurations—including the Brooks knot, standard modified Roeder knot, and Weston knot—proved significantly weaker, generating forces of just 2–18 N. For practitioners seeking to reduce operative costs during laparoscopic procedures, this research supports selective adoption of hand-tied ligatures: specifically, the 4S modified Roeder knot in size 2 polydioxanone offers comparable security to commercial alternatives, though surgeons should recognise that improper technique or alternative knot types risk substantially compromised ligature security with potential clinical consequences. Understanding these mechanical properties allows evidence-based selection of suture techniques without compromising patient safety during minimally invasive procedures.
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Practical Takeaways
- •If using hand-tied ligatures in equine laparoscopy, specifically use the 4S modified Roeder knot with size 2 polydioxanone suture to achieve adequate holding strength
- •Avoid other hand-tied knot configurations as they showed significantly weaker breaking strength and higher failure risk
- •Consider commercially available Endoloop ligatures as the reference standard, but hand-tied alternatives can reduce cost if proper knot technique is used
Key Findings
- •Only the 4S modified Roeder knot with size 2 polydioxanone suture achieved comparable breaking strength (103 N) to square knots (157 N) in mechanical testing
- •All other hand-tied knot configurations tested were significantly weaker than square knots, with breaking strengths ranging from 2-18 N
- •Knot configuration, suture type, and suture size all significantly affected ligature security in laparoscopic slip knots
- •The 4S modified Roeder knot in 2 polydioxanone is a viable alternative to commercially available Endoloop ligatures for equine laparoscopy