Mechanical Design of an Auxiliary Fixation Technique to Make Single Bundle Graft for ACL Reconstruction

Abstract

Purpose: The present study, introduced and mechanically tested an alternative method for graft preparation for ACL reconstruction surgery. The designed method aimed to offer a replacement for conventional suturing which reduces the chance of graft rupture and gradually increases the fixation strength. Methods: to validate the study a set of experiments was performed. Five bovine tendon samples were harvested and trimmed into identical sizes. Samples were passed through two endo buttons and looped in a manner that both ends share a common surface. Two custom straps were later applied around the graft. A three-stage mechanical test was performed, acyclical preload of 10 to 50 N, 10 cycles, and 0.1 Hz. Themajor pullout test with a cyclical load of 50 to 200 N, 1Hz for 200 cycles, and a pull out force with a loading rate of 20 mm/min determining the ultimate strength of the fixation. Results: No failure occurred on the overall structure during the cyclic stages. Also, no failure associated with tendon tissue damage was recorded. All samples experienced a fixation failure during the final pull-out test. The mean values for ultimate strength, cyclicelongation, and Average cyclic Stiffness were 287.66 ±11.84 N, 2.08 ± 0.15 mm, and 14.52 ± 1.09 kN/mm respectively. Conclusions: The results indicate that using the proposed strapping method not only reduces any chance of tendon tearing but also presents acceptable major mechanical properties in comparison with the conventional suturing method. The study showed that the new design was mechanically sound.