Finite element models provide a valuable tool for studying disease progression, risk of tissue failure, or repair strategies. To date, many models for biological tissues employ hyperelastic material descriptions with material properties that have no direct physical interpretation. This seminar will focus on development, validation, and application of a multi-scale structure-based model developed for the intervertebral disc.

The disc is a fiber-reinforced composite structure. Model development was initiated by calibrating model parameters to mechanical behavior at the sub-tissue scale. Fiber bundles and non-fibrous material were modeled as separate materials using triphasic mixture theory, allowing for direct physical interpretation of the material properties. The resulting parameters were used to create tissue- and joint-level models of the disc and the model-predicted mechanical behavior was compared to experimental data in the literature for model validation. Lastly, the model was uses to assess the impact of complex loading on the relative risk of tissue failure. Specifically, the model was used to predict the risk of disc herniation. Findings from this work highlight significant challenges in replicating clinically relevant disc herniation using commonly applied experimental techniques.