Biomechanical and Biological Properties of Stereolithography-Based 3D-Printed Zirconia Interference Screws for Anterior Cruciate Ligament Reconstruction

For effective anterior cruciate ligament (ACL) reconstruction, an interference screw (IFS) is employed to force transplantation of the ligament into the bone tunnel. In this study, IFSs were successfully designed and prepared, and the top tooth width, thread depth, and drive structure were parameterized with a forming accuracy of 80.0 ± 21.1 μm using SLA–3D printing technology. To improve the initial stability of ACL reconstruction, a biomechanical model was established, and the results were optimized through insertion torque and tensile testing. Consequently, the IFS with the top tooth width of 0.4 mm, thread depth of 0.8 mm, and hexagon drive, matching with the Φ8 mm bone tunnel, exhibits the best mechanical properties (maximum insertion torque of 1.064 ± 0.117 N·m, ultimate load of 446.126 ± 37.632 N, stiffness of 66.33 ± 27.48 N/mm). Additionally, the ZrO2/PDA/RGD/Zn2+ bioactive coating was found to significantly improve the surface bioactivity of zirconia IFS. In conclusion, this study has significant implications for ACL reconstruction.