Security Comparison of Various Surgical Knots Using Nylon Suture

ABSTRACT OBJECTIVE To evaluate the strengths of various surgical knot techniques, including square knot, surgeon’s knot, granny knot, and random knot with the same three throws. METHODS The authors tested each of the four knot techniques using four different gauges of nylon (polyamide Ethicon): 4-0, 5-0, 6-0, and 7-0. Each knot type was tested 20 times per nylon gauge, for a total of 320 knots tested. The authors used a static pull machine to measure elongation at yield and maximal force to break. RESULTS A comparison of elongation at yield revealed that the surgeon’s knot was superior to the square knot, granny knot, and random knots across all gauges of nylons. Further, a comparison of maximal force to break revealed that the surgeon’s knot was superior to the square knot, granny knot, and random knots when using 4-0, 5-0, and 6-0 nylon but not when using 7-0 nylon. CONCLUSIONS The surgeon’s knot was the strongest, and random knot was the weakest when the authors used nylon 4-0, 5-0, and 6-0. While handling fine suture materials such as 7-0 nylon, knot failure appears to be unrelated to the knot technique used. This study provides not only fundamental guidance for tying surgical knots using nylon, but also a rational basis for an adequately strong knot choice in various fields of surgery.