A Biomechanical Comparison of Six Suture Configurations for Soft Tissue–Based Graft Traction and Fixation

Abstract

The purpose of this study was to compare 6 different graft fixation techniques to determine the preparation speed, fixation security, biomechanical strength, and resultant tissue trauma. Methods: Six different techniques (10 samples each): #2 OrthoCord Krackow stitch, #2 FiberWire Krackow stitch, SpeedTrap, WhipKnot, Loop-in-loop stitch were created in the distal 3 cm of 9 cm bovine flexor tendons. The proximal 3 cm tendon segment was clamped in a testing machine and the distal suture ends secured by pneumatic grips. 3 preload cycles (10N-100N) and 50N static load was followed by 500 cycles (50N-200N) and then loaded to failure. Graft preparation times, 100 and 500 cycle displacement, maximum failure load, stiffness, and failure mode were recorded. Results: Representative graft preparation times were: OrthoCord Krackow (247s), FiberWire Krackow (401s), FiberLoop (177s), SpeedTrap (42s), WhipKnot (39s), Loopin-loop (45s). No WhipKnots survived cyclic loading. 100 cycle displacements were: OrthoCord Krackow (11.5 AE 3.9 mm), FiberWire Krackow (8.9 AE 1.2 mm), FiberLoop (14.2 AE 6.1 mm), SpeedTrap (8.8 AE 2.5 mm), Loop-in-loop (10.4 AE 2.9 mm). FiberLoop displaced significantly more than all others (P ¼ .016). Maximum failure loads were: OrthoCord Krackow (364 AE 24N), FiberWire Krackow (375 AE 45N), FiberLoop (413 AE 95N), SpeedTrap (437 AE 65N), WhipKnot (153 AE 42N), Loop-in-loop (329 AE 112N). The most common failure mode was suture breaking. FiberWire containing constructs (Krackow and FiberLoop) shredded or cut through ("cheese wiring") prior to failure in a majority. Conclusions: SpeedTrap, WhipKnot and Loop-in-loop were quickest to create (under 1 minute). The Krackow, SpeedTrap, WhipKnot, and Loop-in-Loop did not damage the tendon during cyclic loading. SpeedTrap and Krackow had the least displacement. FiberLoop displaced more than all other groups (P ¼ .016). No WhipKnot completed cyclic loading. The SpeedTrap (437N) and FiberLoop (413N) had the highest ultimate strength. Clinical Relevance: While the SpeedTrap and FiberLoop are the strongest techniques, the FiberLoop shreds the tendon, displaced the most, and took longer to create. Based on these results, the SpeedTrap demonstrates the best overall performance.

The Biomechanical Properties of a High-Tensile Strength Tape for Tendon Graft Fixation Using the Krackow Configuration

“…The parameters in the biomechanical testing protocol were in accordance to previous studies. 1,4,9,[15][16][17][18][19][20][21] All specimens were initially pretensioned to 100 N at a rate of 100 mm/min for 3 cycles and then preloaded to 50 N for 1 minute. After that, each specimen was cyclically loaded between 50 and 200 N with a cross-head speed of 200 mm/min for 200 cycles.…”

“…[1][2][3][4] In past decades, various suture techniques have been addressed for tendon graft fixation 1,[3][4][5][6][7][8] ; among these techniques, the Krackow suture 6 remains the most popular because it provides superior biomechanical properties. [9][10][11] In addition to the suture technique, the type of suture material may also affect the fixation strength of a suture-tendon construct. 12 Gnandt et al 12 compared the biomechanical properties of a high-tensile strength tape and a high-tensile strength suture in tendon graft fixation.…”

“… 1 , 2 , 3 , 4 In past decades, various suture techniques have been addressed for tendon graft fixation 1 , 3 , 4 , 5 , 6 , 7 , 8 ; among these techniques, the Krackow suture 6 remains the most popular because it provides superior biomechanical properties. 9 , 10 , 11 …”

Editorial Commentary: Stronger and Faster Suture Configuration—But Is It Better? Challenges of Surgical Innovation in the Modern Era

“…Barber et al 3 have successfully tested the new against the tried and true. I wonder if there may be an era when future orthopaedic surgeons routinely fix suture to grafts only with rapid, needleless techniques.…”

Does using high-tensile strength tape improve the fixation strength in tendon graft fixation with needleless suture wrapping techniques compared to a suture?

“…[2][3][4][5] Among these techniques, the Krackow suture technique 3 is especially popular due to its superior biomechanical properties. [6][7][8] However, it is worth noting that passing sutures through tendons is time-consuming 9 and will possibly cause tendon damage; additionally, potential risk of needlestick injury is also a concern.…”