B. Slatnick1, E. Day1, S. Asghar1, V. Y. Dombrovskiy1, T. Davidov1 1Rutgers, Robert Wood Johnson Medical School,General Surgery,New Brunswick, NJ, USA
Introduction:
Surgeon preference dominates choice on number of knots and type of suture material for surgical closures. For abdominal wall closures, #1 Polydioxanone suture (PDS) is recommended due its high tensile strength and absorbable nature. While “square knots” on monofilament suture are anecdotally known to be stronger than sliding knots, this is not well quantified. Furthermore, the optimal number and type of knots with PDS suture for abdominal wall closure is poorly defined. Our previous study shows that addition of one-handed sliding crossed knots with PDS suture decreases knot failure rate in a linear fashion. However, even with 12 knots there was a 10% failure rate. This study seeks to determine the mechanical properties of square knots (or two handed knots) on PDS and define the optimal number of knots required to prevent knot failure.
Methods:
Square crossed knots were tied with 4, 6, or 8 throws using #1 PDS Suture. A single surgeon hand tied a total of 90 samples in randomized order: 30 samples for each group over 2 sessions to prevent fatigue. Using a tensilometer, knots were tested to the point of knot failure—defined as the knot untying before the suture breaks. The peak force in Newtons (N) was recorded at knot failure. We then compared knot failure rates and peak forces between this model and our previous study. Chi squared analysis, t-test, and general linear modeling was used for intergroup comparisons.
Results:
Square knots had decreased knot failure rates compared to one handed sliding crossed knots with the same number of throws. Square knots with 4, 6, and 8 throws had knot failure rates of 90, 0 and 0% respectively. There was no difference in knot failure rates between 4 one handed sliding crossed knots and 4 square knots (P= 0.45); however, with 6 or 8 square knots there were no failures compared to 70% and 43% for one handed sliding crossed knots respectively. At 4 knots, 52 N were required on average for knot failure in the one-handed sliding crossed group vs. 70 N for square knots.
Conclusion:
Square knots are superior to one-handed sliding crossed knots using #1 PDS. Square knots with 6 throws are the optimal number to prevent knot failure.
