Primary Proximal ACL Repair: A Biomechanical Evaluation of Different Arthroscopic Suture Configurations

Purpose: Several suture techniques have been described in the past for direct ACL repair with poor healing capacity and a high re-rupture rate. Therefore, we investigated a refixation technique for acute primary proximal ACL repair. The purpose of this study is to compare the biomechanical properties of different suture configurations using a knotless anchor. Methods: In this study, 35 fresh-frozen porcine knees underwent proximal ACL refixation. First, in 10 porcine femora, the biomechanical properties of the knotless anchor, without the ligament attached, were tested. Then, three different suture configurations were evaluated to reattach the remaining ACL. Using a material testing machine, the structural properties were evaluated for cyclic loading followed by loading to failure. Results: The ultimate failure load of the knotless anchor was 198, 76 N +/- 23, 4 N significantly higher than all of the tested ACL suture configurations. Comparing the different configurations, the modified Kessler-Bunnell suture showed significant superior ultimate failure load, with 81, 2 N +/- 15, 6 N compared to the twofold and single sutures (50, 5 N +/- 14 N and 37, 5 +/- 3, 8 N). In cyclic loading, there was no significant difference noted for the different configurations in terms of stiffness and elongation. Conclusions: The results of this in vitro study show that when performing ACL suture using a knotless anchor, a modified Kessler-Bunnell suture provides superior biomechanical properties than a single and a twofold suture. Within this construct, no failure at the bone-anchor interface was seen.