Knot Security- How is it Affected by Suture Technique, Material, Size, and Number of Throws?

PURPOSE

To measure knot security in relation to different surgical knotting techniques, suture materials, suture sizes, and number of throws commonly used in oral and maxillofacial surgery.

MATERIALS AND METHODS

Three surgical tying techniques were tested: square, surgeon's, and sliding knots. Suture materials included chromic gut, nylon, silk, and Vicryl (polyglycolic acid). Suture diameter sizes 3-0, 4-0, and 5-0 were tested. Ten trials were undertaken for each combination of material, size, and technique using 2, 3, 4, 5, and 6 throws (ties). Suture materials were presoaked in 0.9% saline solution for 15 minutes to simulate the environment of the oral cavity. A standard knot-tying force for each throw was applied to each combination. Knot security satisfaction was set from pilot experimental trials at less than 1.8-mm slippage from the center of the knot while testing. The dichotomous outcome of knot slippage (stable or unstable) was analyzed using logistic regression analysis and odds ratios with Tukey-adjusted 95% confidence intervals.

RESULTS

Knot security depended on suture technique, material, and number of throws but did not depend on suture size. In general, 4 throws were required for surgeon's and square knots, whereas 5 throws were required for sliding knots. After 5 throws, tying an additional throw did not contribute to knot security. Surgeon's knots were stronger than square knots and sliding knots (P < .0001 and P < .0001). Square knots were stronger than sliding knots (P = .01). Vicryl had the greatest knot security, followed by chromic gut, nylon, and silk.

CONCLUSION

This study showed that knot security depends on suture material, tying technique, and number of throws, but is independent of suture size. Surgeon's knot security was greater than that for square and sliding knots when using sutures commonly used in the oral cavity. Vicryl had the greatest knot security and silk had the least. For surgeon's and square knots, at least 4 throws were generally indicated to achieve knot security; for sliding knots, at least 5 throws were generally indicated. Knot security did not increase after 5 throws and 2 throws are never indicated.