Design Consideration for ACL Implants based on Mechanical Loading

This study aims to understand and estimate the forces while the anterior cruciate ligament (ACL) is subjected to loading during stair negotiation. 9 healthy subjects were recruited and asked to negotiate stairs while their motion was captured. An OpenSim model was developed to estimate the ACL length from kinematic data. The forces were estimated using a force/displacement relationship. The peak ACL force was 0.416±0.089 N/BW and was recorded at full extension of the knee while the participants were descending stairs. The forces experienced by the right and left ACL of women were highly significant compared to ACL forces in men and the ACL forces in old people were significantly higher than in younger people. These forces will be used as boundary conditions in a novel finite element model (FEM) to estimate tensile and shear stress levels in the ACL to gain design information to create a tissue engineered ACL implant. The CIRP-Biomanufacturing conference promotes the exchange of knowledge on biodesign and biofabrication in order to develop novel medical devices for improving quality of life. This work is relevant to the conference since it contributes to a better understanding of the mechanical behavior of ACL throughout its range of motion and it is the starting point for the design and manufacture of new ACL implants.