Strength of Damaged Suture: An In Vitro Study

Purpose: To determine the mechanical properties of damaged suture. Methods: Undamaged and damaged sutures were tested by a single pull to failure. Sutures were damaged with a razor blade incorporated into a custom-designed jig. Sutures were tested to failure by straight pull and by pulling at 180° through a suture anchor eyelet. The friction of sutures through anchors was also tested. Results: For the straight line pull test, undamaged FiberWire (Arthrex, Naples, FL) had the highest load to failure (LTF) and ultimate tensile strength (UTS) of all sutures tested. Undamaged Orthocord (Mitek, Somerville, NJ) ranked second in both properties. Uncut polydioxanone (PDS) suture (Ethicon, Somerville, NJ) had a higher LTF and a comparable UTS with respect to Tevdek (Deknatel, Mansfield, MA) and Ethibond (Ethicon). For cut sutures, FiberWire and Orthocord had a significantly higher LTF and UTS than the other sutures tested. Suture stiffness was not significantly affected when the suture was cut. For the suture anchor test, FiberWire and Orthocord had the highest LTF, whether undamaged or damaged. When cut, PDS had the greatest loss of LTF and UTS during both tests. Conclusions: The newer polyethylene core sutures (FiberWire and Orthocord) have superior mechanical properties compared with other sutures. Their superior properties are maintained even when cut. Although uncut PDS had equivalent or superior strength compared with Ethibond and Tevdek, once cut, PDS suture was weakened significantly more compared with all other sutures tested. Clinical Relevance: The mechanical properties of damaged suture are important to all surgeons who use suture arthroscopically.