In Vitro Biomechanical Testing of the Tube Knot.

ObjectiveTo compare in vitro biomechanical properties of the tube knot (TB) to a crimp clamp (CC) system, and square knot (SQ) using 3 monofilament materials. Study DesignIn vitro biomechanical study. Sample PopulationSuture loops (n=20 per material/knot construct). MethodsMonotonic tensile loading (300 mm/min single pull to failure) was performed on knots tied using 3 knots (TB, 5-throw SQ, and CC system) with each of 3 materials (40# Securos (R) nylon, #2 polypropylene, and #2 nylon). Ultimate tensile strength, elongation, and stiffness were measured and compared by sequential 1- and 2-way ANOVA. ResultsUltimate tensile strength was greatest with 40# nylon CC (meanSD, 293.6 +/- 26.2 N), followed by TB (289.8 +/- 9.2 N) and SQ (252.2 +/- 8.5 N) with no significant difference between CC and TB. TB with #2 polypropylene (158.1 +/- 7.4 N) and #2 nylon (126.3 +/- 5.5 N) had significantly greater tensile strength than SQ with #2 polypropylene (143.6 +/- 5.3 N) and #2 nylon (110.7 +/- 6.2 N). Elongation at failure was significantly greater in 40# nylon TB (25.3 +/- 3.2 mm) and SQ (10.8 +/- 1.6 mm) compared to CC (5.3 +/- 1.0 mm). Both material and knotting method had an effect on ultimate tensile strength, elongation at failure, and stiffness, based on 2-way ANOVA. ConclusionUltimate tensile strength of TB was equivalent to that of CC; however, elongation at failure was greatest for TB, which may be of concern for clinical applications.