Running sutures anchored with square knots are unreliable

Background: A previous study showed that running polypropylene sutures anchored with square knots retain only 75% of their strength compared with half hitches. The aim of this study was to investigate whether anchor knot geometry similarly affects the tensile strength of other types of sutures used in continuous closures.

Methods: Monofilament and multifilament sutures (all 3-0) were anchored with either square knots or half hitches to 1 tensionometer post, and the running ends were secured to the other. The force required to break the running suture and the site of suture failure were recorded.

Results: The running sutures anchored with square knots retained only 50% to 84% of the strength of the identical sutures secured with half hitches (P < .001).

Conclusions: A running suture anchored with half hitches is stronger and safer in comparison with the same suture anchored with square knots. This study provokes a fundamental reconsideration of the use of square knots to anchor running sutures.