A biomechanical comparison of anterior cruciate ligament suspensory fixation devices in a porcine cadaver model.

Abstract

Suspensory fixation use during anterior cruciate ligament reconstruction has increased due to ease of use and high pullout strength. We hypothesize that there are no significant differences in biomechanical performance among four types of suspensory fixation devices: Stryker VersiTomic G-Lok, Smith & Nephew Endobutton, Biomet ToggleLoc, and Arthrex RetroButton. Forty fresh frozen porcine femurs and flexor digitorum profundus tendons were obtained. Each tendon graft was sized to 8.5mm or 9.0mm. Ten of each device were used to fix the grafts in the femur at the 2 o'clock (left) or 10 o'clock (right) position. The graft-femur complex was secured to a servohydraulic test machine in line with the femoral tunnel. The graft was cyclically loaded from 50 to 250 N for 1000 cycles at 1 Hz then loaded to failure at 20mm/min. Actuator load and displacement were recorded. Data were analyzed with multiple one-way ANOVA and Tukey HSD post-hoc tests. Bonferroni correction was applied resulting in P ≤ 0.005 considered statistically significant for ANOVA, P ≤ 0.05 for Tukey. There were no significant differences in cyclic displacement among any of the groups (P=0.43). The only significant difference in failure properties is the Endobutton exhibited at least 50% greater displacement at failure than the other three devices. Suspensory femoral soft tissue fixation devices are biomechanically similar with respect to failure load but differ in failure displacement. However, there was no significant difference in displacement after cyclic loading. All four fixation devices should withstand the forces associated with daily activities without failure.