Surgically Adjust Tibial Tunnel in Anatomical Anterior Cruciate Ligament Single-Bundle Reconstruction: A Time-Zero Biomechanical Study In Vitro

Abstract

Abstract Background The anatomical positioning of the graft during anterior cruciate ligament reconstruction is of great significance for restoring normal knee kinematics and preventing early joint degeneration.The first attempt to place a guide wire in the center of the tibial footprint may be mispositioned. Therefore, its adjustment is important to achieve the anatomical positioning of the graft in the tibial footprints. Our research aims to test the time-zero biomechanical properties in adjusting inaccurate guide pins to the center of the tibial footprint in anatomical anterior cruciate ligament single-bundle reconstruction. Methods Porcine tibias and bovine extensor tendons were used to simulate a transtibial ACL reconstruction in vitro. Load-to failure testing was carried out in 4 groups: the Control group (n = 8): the guide pin was drilled at the center of the ACL footprint. Group I (n = 8): the guide pin was drilled 1 mm away from the center of the ACL footprint. Group II (n = 8): the guide pin was drilled 2 mm away from the center of the ACL footprint. Group III (n = 8): the guide pin was drilled 3 mm away. In the experiment groups, a small tunnel with a 4.5-mm reamer is made and the guide pin is shifted to the center of the footprint. All the reamed tibias were scanned by CT to measure the area of the tunnel in the footprint, and the load-elongation curve, tensile stiffness (in newtons per millimeter), ultimate load (in newtons), yield load (in newtons), energy absorbed to failure (in joules), and failure mode were recorded after the grafts were fixed by interference screws. Results All graft-tibia complexes failed because the grafts slipped past the interference screws. Regarding the tensile stiffness, ultimate load, yield load, energy absorbed to failure, twisting force, and tunnel exit area, ANOVA showed no significant differences among the groups (P > 0.05). No significant differences in biomechanical properties were found between groups (P > 0.05). Conclusions Surgical adjustment of the guide pin to the center of the tibial footprint may has no influence in time-zero biomechanical properties in anatomical anterior cruciate ligament single-bundle reconstruction.