Biomechanical, histologic, and molecular characteristics of graft-tunnel healing in a murine modified ACL reconstruction model

The study introduced a metal-free, reproducible, and reliable mouse model for anterior cruciate ligament reconstruction (ACLR) to better understand the molecular mechanisms of graft-tunnel healing. Using 150 C57BL/6 mice divided into five groups, the research employed micro-computed tomography, biomechanical, histological, and immunohistochemical analyses. Results showed non-significant increases in bone volume and density during healing, with biomechanical tests indicating reduced load-to-failure forces and stiffness in modified ACLR groups compared to intact ACLs. Histological analysis revealed fibrovascular tissue formation and direct junctions between tendon grafts and tunnels. Immunohistochemical results highlighted changes in the expression of key molecules in Ihh signaling during healing. The study validated the mouse model's potential for investigating molecular mechanisms and exploring strategies to enhance tendon-to-bone integration.