Biomechanical Evaluation of Modified Ti6Al4V Ligament Anchors with Varied Expansion Directions for Anterior Cruciate Ligament Reconstruction

Expansion-type anchors have been developed as an alternative to conventional fixation devices, such as screw-type and button-type anchors, for anterior cruciate ligament (ACL) reconstruction. Here, we present novel expansion-type anchors that minimize damage to both bone tissue and the transplanted ligament during surgery, potentially leading to improved postoperative outcomes for patients. The biomechanical performance of two different expansion-type ACL anchors, the 2 expansion directions type anchor (2EDA) and the 4 expansion directions type anchor (4EDA), was evaluated through finite element analysis. The required force for complete retraction, as well as the stress distribution of the device during the retraction and expansion procedures, was precisely evaluated. Subsequently, we assessed displacement distance and the applied maximum force on bone models under conditions of vertical and oblique force application. The results revealed that both 2EDA and 4EDA for ACL reconstruction have clinical potential, providing sufficient fixation ability under a maximum loading force of 500 N. In this study, we confirmed that ACL reconstruction using the modified expansion-type anchors is a promising approach to enhancing artificial ligament fixation and reducing the risk of postoperative complications. Notably, both 2EDA and 4EDA anchors demonstrated clinical potential, while the 2EDA exhibited improved performance in terms of displacement distance, applied stress, and stress distribution within the bone tunnel.