Mechanical properties of newly developed loop ligament for connection between the EndoButton and hamstring tendons: comparison with Ethibond sutures and Endobutton tape.

Abstract

A new artificial loop ligament (LL) without mechanical weak points, such as a knot, has been developed to connect the EndoButton and hamstring tendons for anterior or posterior cruciate ligament (CL) reconstruction. This study assessed the mechanical properties of the LL and sutures (No. 5 Ethibond thread, EndoButton tape) and those of the different CL constructs with these materials and fixation devices commonly used in CL reconstruction. The LL had a significantly higher ultimate tensile load (UTL) and stiffness value (p < 0.001) than No. 5 Ethibond thread or EndoButton tape in static and fatigue tests (50--500 N, 1.08 million cycles). The LL-tendons-Leeds-Keio artificial ligament-staple construct complex also had significantly higher UTL and stiffness value than the Ethibond loops or EndoButton tape loop-tendons-Ethibond sutures-postscrew-fixed construct complex. Furthermore, the LL construct complex elongated the least after cyclic loading (50--150 N, 90,000 cycles). These findings suggested that using the LL construct complex might avoid a bungee cord effect and elongation before biological healing between the construct and bony socket. The LL construct complex could be a safe substitute for use during the postoperative period.