A Dynamic, Self-Tensioning Suture Contracts in Saline to Counteract Changes in Loop Length From Cyclic Loading

Purpose: To compare the biomechanical performance of a suture with proposed dynamic self-tensioning properties with that of commonly used high-tensile sutures by evaluating suture loop length changes, responses to cyclic loading, and failure testing with intermittent saline soaks.

Methods: Six knots each of 4 different sutures were studied: 3 high-tensile sutures (ORTHOCORD, FiberWire, and ETHIBOND), and a dynamically self-tensioning suture (DYNACORD). After we measured loop length, knots were soaked in 37°C saline for 24 hours. Loop lengths were remeasured and tensile testing was performed. Cyclic elongation, first-cycle excursion, and elongation amplitude were recorded. Knots were then resoaked and retested. Finally, knots were pulled to failure, and peak load and stiffness were measured. Values were compared using nonparametric statistical tests.

Results: DYNACORD loop length decreased by 27% after the first soak (P = .002), whereas the other sutures demonstrated no length change (P > .05). Although DYNACORD loop length increased during cyclic load testing (P = .009), it was still significantly reduced after the second saline soak compared with its initial length (P = .002), whereas all other suture loops had elongated. ETHIBOND (P = .004) and ORTHOCORD (P = .002) had significantly less cyclic elongation from cycle I to cycle II testing compared with the other sutures. ETHIBOND had the lowest peak load at failure (P = .002). FiberWire had the greatest stiffness (P = .006).

Conclusions: Compared with other suture types, the self-tensioning suture showed dynamic properties, demonstrating a decrease in loop length when soaked in a saline bath. This length was maintained after a second soak despite increased loop length during interval cyclic loading.

Clinical relevance: Knot and loop security are of paramount importance to arthroscopic soft-tissue procedures. The ability for a suture to self-tension has implications for how it may interact with tissues in vivo to increase construct stability after arthroscopic soft tissue repair procedures.