Using half-hitch knots to uncouple surgical knot security and loop tautness.

BACKGROUND

Most surgeons tie half-hitch knots, but many are unfamiliar with the principles underlying their security leading to insecure knots. When presented with evidence regarding tying technique and knot security, we note a proclivity among surgeons towards resistance to change with rationalizations such as concerns regarding tissue strangulation with increasing knot security. We hypothesize that this concern is unfounded. The aim of this study was to identify whether the impact of loop tautness on knot security is mediated through the configuration of the knot.

METHODS

Six-throw knots were tied with 0 silk. The loop of the knot encompassed two brass rings and a piece of latex hose. Four knot types were tied and tested: non-taut and taut single post knots (SxSxSxSxSxS in Dinsmore notation), and non-taut and taut alternating post knots (SxSxS#S#S#S in Dinsmore notation). The latex hose was then removed from the loop and the brass rings were distracted on a tensiometer to assess knot security. The main outcome for the study was knot security, including maximum force resisted by each knot type to 1 and 2 mm slippage and ultimate failure defined by slippage to unraveling or breakage of the suture. Differences of means were tested with 2-sided t-test.

RESULTS

By 1 mm slippage, the tautly tied alternating post knots were more secure than the single post knots, and the non-taut single post knots were less secure than all other configurations. By 2 mm slippage, the tautly tied alternating post knots were more secure than all other configurations and the non-taut alternating post knots were more secure than the tautly tied and non-taut single post knots. By ultimate failure, the tautly tied and non-taut alternating post knots were comparable and both more secure than both single post knots.

CONCLUSIONS

Surgeons can utilize single and alternating post throws to independently confer knot security and loop tautness and thereby tie the knot needed under a given set of circumstances.