Biomechanical Effects of Loop Thickness in ACL Graft: A Simulation Study

A cortical suspension device that combines a loop and a button is used widely for anterior cruciate ligament reconstruction surgery. Although various biomechanical studies using these devices have been conducted, relatively few have explored the biomechanics of the wire-graft contact region depending on the thickness of the loop wire. In this study, the effects of loop thickness on the graft contact region were tested, and the recommended loop thickness was analyzed by constructing a simulation model to reflect this effect. Five groups of specimens were prepared by combining 50 porcine tendons and loop wires with thicknesses ranging from 1.5 to 3.5 mm at 0.5-mm intervals, and the elongation and hardness changes in the contact region were measured and recorded. In addition, the maximum stress on the graft was analyzed by a computer simulation model based on the biomechanical test results. Statistically significant elongation and contact hardening occurred in the thin loop wires ≤ 3.0 mm. In addition, larger amounts of contact stress were found for loops with a thickness ≤ 2.5 mm. In consideration of elongation and contact stress, loops with a thickness ≥ 3.0 mm are recommended for ACL reconstruction.