Viscoelastic Properties of Common Suture Material Used for Rotator Cuff Repair and Arthroscopic Procedures

Purpose: The purpose of this study was to evaluate the viscoelastic properties of 5 suture materials, commonly used in arthroscopic rotator cuff repairs, when subjected to physiological loads. Methods: We evaluated 5 commercially available No. 2 sutures undergoing both creep and cyclic testing in both dry air and phosphate-buffered saline solution (PBS) maintained at 37 degrees C. The selected sutures were MagnumWire (ArthroCare, Austin, TX), Ethibond (Ethicon, Somerville, NJ), FiberWire (Arthrex, Naples, FL), Orthocord (DePuy, Warsaw, IN), and Force Fiber (Tornier, Bloomington, MN). Results: Regarding creep testing, in the PBS test environment, FiberWire showed the greatest stiffness (71.1 +/- 2.1 N/mm), the smallest initial extension at the 60-N load (1.10 +/- 0.04 mm), and the smallest amount of creep (0.57 +/- 0.01 mm). Orthocord showed the smallest amount of relaxed elongation in PBS (0.73 +/- 0.11 mm). Regarding cyclic testing, in the PBS testing environment, Ethibond exhibited the smallest dynamic creep (0.28 +/- 0.02 mm), FiberWire displayed the smallest peak-to-peak displacement (0.17 +/- 0.00 mm), and Orthocord showed the smallest amount of relaxed elongation after cyclic loading (0.63 +/- 0.11 mm). Conclusions: FiberWire consistently displayed more extreme viscoelastic properties-greater stiffness and less extensibility-than the other suture types studied. Orthocord showed the smallest amount of relaxed elongation in both testing environments. Differences in testing environment affect the behavior of each suture type. Testing in physiologically approximating conditions such as PBS maintained at 37 degrees C is warranted.