Biomechanical Strength of All-Inside ACL Reconstruction Grafts Using Side-to-Side and Backup Fixation

Abstract

Background: The all-inside anterior cruciate ligament reconstruction (ACLR) procedure uses a single hamstring tendon folded twice and secured to itself to form a 4-stranded graft. There are several possible configurations for preparing the graft. Purpose: To investigate the biomechanical properties of a new graft preparation technique in comparison with 2 commonly used configurations. Study Design: Controlled laboratory study. Methods: Five porcine flexor tendons were prepared into the test graft configuration: side-to-side fixation with a backup fixation at the button loop (graft M). The test configuration was compared with the results of a previous study that included grafts with simple interrupted sutures (graft A; n = 5) and end-to-end fixation (graft C; n = 5). All grafts were subjected to the same mechanical testing protocol to determine the mean failure load, stiffness, rate of elongation, and total elongation during both cyclic loading and pull to failure. Differences between groups were evaluated. Results: Graft A had a significantly lower failure load (637 ± 99 N) compared with graft M (883 ± 66 N; P =.002) and graft C (846 ± 26 N; P =.002). Graft A also had significantly lower stiffness (166 ± 12 N/mm) compared with graft M (215 ± 8 N/mm; P