Knot security, loop security, and elongation of braided polyblend sutures used for arthroscopic knots

In the study described here, we evaluated load to failure and cyclic loading elongation of different braided polyblend sutures under different sliding knot configurations. Four braided polyblend sutures (FiberWire, Herculine, Orthocord, Ultrabraid) were tied with 5 sliding arthroscopic knots (Static surgeon, Weston, Roeder, Nicky, Tennessee slider) with a series of 3 reversing half-hitches on alternating posts (RHAPs). Each knot was tied around a 30-mm circumference post to ensure a consistent loop circumference. Loop security was measured as load to failure (load at 3-mm cross-head displacement or suture breakage) and loop elongation at a frequency of 1 Hz from 6 N to 30 N for 1000 cycles. Twenty knots were tied for each possible combination of knots and sutures, 10 for load to failure and 10 for cyclic loading test. For any given knot type, tying with Ultrabraid suture material resulted in maximum performance in the maximum load-to-failure test. Conversely, tying with Orthocord resulted in a significantly lower maximum load to failure, with the exception of the Surgeon knot. The Weston knot with 3 RHAPs using Ultrabraid provided the highest load to failure(mean, 346 N; SD, 24 N). All knots elongated less than 0.45 mm at the 1000th cycle and experienced higher suture slippage at initial cyclic loading (50th cycles). At higher cycles, FiberWire and Orthocord demonstrated less than half of the suture slippage of Herculine and Ultrabraid (5x10(-5) vs 11x10(-5) mm/cycle). Different braided polyblend sutures provide different knot and loop security for a given type of sliding knot. All knots in this study appear to be durable with respect to resistance to loosening under cyclic loading conditions. The Weston knot with 3 RHAPs using Ultrabraid provided the best loop and knot security. Our study results help further our understanding of the biomechanics of knot and loop security differences for different braided polyblend sutures.