MEMS Seminar - PEARSALL LECTURE: Full-Field Methods for Characterizing the Non-Linear Anisotropic Response of the Anterior Cruciate Ligament of the Knee

The Anterior cruciate ligament, or ACL, of the knee is a soft tissue structure comprised of two main bundles of hierarchical collagenous structures. As with all soft tissue, the ACL is extremely difficult to mechanically test, and determining its non-linear, anisotropic mechanical response has remained elusive. Yet, obtaining the mechanical properties of the ACL is exceedingly clinically relevant to the design of better replacement grafts for torn ACLs or to prevent ACL tears in the first place. This talk will focus on our recent efforts to characterize the ACL response utilizing full-field displacement measurement techniques that offer more accurate, repeatable, and comprehensive experimental data than traditional testing methods. We've pioneered full-volume characterization techniques that provide much needed insight into the inaccuracies associated with many current experimental protocols and also the shortcomings of some popular constitutive models in capturing the full 3D response of the ACL. I will describe how we use these data to develop an ACL constitutive model for implementation into computational models of the knee during regular gait and under impact loading simulations. Accurate computational models of the knee such as ours may one day be used to guide clinical practice to intervene to prevent an ACL injury or to determine the best course of action to repair an injury.