|Beitragstitel||What is the best surgical knot for high-strength suture material? A biomechanical study|
Background: Almost every surgery requires the use of surgical knots. Double-stranded looped configuration may be advantageous due to fewer free suture ends and machanical properties. The objective was to compare novel looped to conventional knot configurations.
Methods: In an in vitro biomechanical study, 12 different knots were repeatedly (five times each) tested with a distraction material testing machine with a constant displacement speed (0.2 millimeters/second [mm/s]). The knots were the conventional half hitch, square knot with secured ends, eight-sling-eight with secured ends, Nicky’s knot, Nice knot, racking hitch, cow hitch (Larks head), clove hitch, altered (arthroscopic version) cow hitch with four knots, altered clove hitch with four knots, altered cow hitch with five knots, altered clove hitch with five knots. Afterward, the cow hitch, its arthroscopic version, and conventional half hitches were investigated on bovine tendon. Braided polyblend non-bioresorbable suture material was used. Knot security (stiffness) at assumed clinical failure (≥3mm displacement) was the primary outcome. Size and loop security (maximal tension) was the secondary outcome. A power analysis was done based on pre-test results. Oneway ANOVA and post hoc tests with Bonferroni correction was used to compare groups. Statistical significance was assumed for p-values <0.05.
Results: Compared to one and a half- and single-stranded knots, double-stranded looped knots were up to three times stronger. The stiffest knot was the cow hitch (mean 184.7 [95% confidence interval 172.0-197.4] Newton [N]/ mm) (p<0.001), tailed by the Nice knot (168.6 [154.0-183.2] N/mm). Coventional half hitches were less stiff (65.4 [52.9-77.9] N/mm). These findings remained in tendons (81.8 [77.1-86.4] and 40.4 [32.0-48.8] N/mm, p<0.001). Half hitches (9.5mm3) were larger than cow hitches (7.6mm3) and Nice knots (6.1mm3). Cow hitches had higher loop security than half hitches (157.6 [119.6-195.6]N and 85.0 [56.9-113.2]N, p<0.001).
Conclusions: Double double-stranded surgical knots with a loop on one side are mechanically stiffer (stronger), smaller, and keep applied tension better than conventional knots. The cow hitch and Nice knot seem to be the knots with the best performance, while being simple to tie.
[Note: This abstract has also been submitted to the 18th EFORT Congress 2017, Vienna, Austria.]