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Published on: May 19, 2014
Minimum number of throws needed for knot security
Tyler M Muffly1, Nathan Kow, Imran Iqbal
1Center for Urogynecology and Reconstructive Pelvic Surgery, Obstetrics, Gynecology and Women's Health Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA. tylermuffly@hotmail.com
Objective:
The purpose of the study was to determine the optimal number of throws to ensure knot security.
Study Design:
Knots were tied with 3, 4, 5, or 6 square throws with 0-gauge coated polyester, polydioxanone, polypropylene, and polyglactin 910. The suture was soaked in 0.9% sodium chloride and subsequently transferred to a tensiometer and broken.
Results:
A total of 225 knots were tied. Regardless of the suture type, tension at failure for knots with 4 throws, 5 throws, and 6 throws was higher than tension at failure of knots with only 3 throws (p < 0.05 for each). We found no difference in the tensile strength between knots with 4, 5, or 6 throws (p > 0.05 for each). Knots with 4 throws were significantly more likely to come untied than knots with 5 or 6 throws (p < 0.01).
Conclusions:
Under laboratory conditions, the ideal knot has 5 throws to maximize tensile strength and rate of untying. This finding does not seem to vary by type of suture material.
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