Suture Tape Augmentation Improves the Biomechanical Performance of Bone-Patellar Tendon-Bone Grafts Used for Anterior Cruciate Ligament Reconstruction

Abstract

The purpose of this study was to investigate the time-zero biomechanical properties (stiffness, displacement, and load at failure) of bone-patellar tendon-bone (BTB) grafts used for anterior cruciate ligament (ACL) reconstruction with and without suture tape augmentation as a means to determine the potential clinical benefit of this technique. Eight juvenile porcine knees underwent ACL reconstruction with a human cadaveric BTB graft (control). These were compared to 8 juvenile porcine knees that underwent ACL reconstruction with a BTB graft augmented with suture tape. All knees underwent biomechanical testing utilizing a dynamic tensile testing machine. Cyclic loading between 50-250N was performed for 500 cycles at 1 Hz to simulate invivo ACL loads during the early rehabilitation phase. The grafts were displaced during load-at-failure tensile testing at 20 mm/min. Differences in graft displacement, stiffness, and load at failure for the control and suture tape augmented groups were compared with the Student t-test with a significance level of P < .05. There was no difference in graft displacement between the 2 groups. A 104% higher postcyclic stiffness was noted in the augmented group compared to the controls (augmentation: 261 ± 76 N/mm versus control 128 ± 28 N/mm, P= .002). The mean ultimate load at failure was 57% higher in the augmented group compared to controls (744 ± 219 N vs postcyclic 473 ± 169 N, respectively [P= .015]). There was no difference in mode of failure between the control knees and those augmented with suture tape, with approximately half failing from pull off of the tendon from the bone plug and half with pull out of the bone plug from the tunnel. Independent suture tape augmentation of a BTB ACL reconstruction grafts was associated with a 104% increase in graft stiffness and a 57% increase in load at failure compared to nonaugmented BTB grafts. Invivo suture tape augmentation of a BTB ACL reconstruction increases graft construct strength and stiffness, which may reduce graft failure in the clinical setting.