Comparing the tensile strength of square and reversing half-hitch alternating post knots

Square knots are the gold standard in hand-tie wound closure, but are difficult to reproduce in deep cavities, inadvertently resulting in slipknots. The reversing half-hitch alternating post (RHAP) knot has been suggested as an alternative owing to its nonslip nature and reproducibility in limited spaces. We explored whether the RHAP knot is noninferior to the square knot by assessing tensile strength.

We conducted 10 trials for each baseline and knot configuration, using 3-0 silk and 3-0 polyglactin 910 sutures. We compared tensile strength between knot configurations at the point of knot failure between slippage and breakage.

Maximal failure strength (mean ± SD) in square knots was reached with 4-throw in both silk (30 ± 1.5 N) and polyglactin 910 (39 ± 12 N). For RHAP knots, maximal failure strength was reached at 5-throw for both silk (31 ± 1.5 N) and polyglactin 910 (41 ± 13 N). In both sutures, there were no strength differences between 3-throw square and 4-throw RHAP, between 4-throw square and 5-throw RHAP, or between 5-throw square and 6-throw RHAP knots. Polyglactin 910 sutures, in all knot configurations, were more prone to slippage than silk sutures (p < 0.001).

The difference in mean tensile strength could be attributed to the proportion of knot slippage versus breakage, which is material-dependent. Future studies can re-evaluate findings in monofilament sutures and objectively assess the reproducibility of square and RHAP knots in deep cavities. Our results indicate that RHAP knots composed of 1 extra throw provide equivalent strength to square knots and may be an alternative when performing hand-ties in limited cavities with either silk or polyglactin 910 sutures.