Mathematical models of biologic structures such as the knee, spine, and hand provide opportunities to better understand complex interactions and to simulate treatment outcomes. Accurate estimates of the material properties of biologic soft tissues are critical to the fidelity of biomechanical models. Biologic soft tissues have a nonlinear mechanical behavior characterized by an exponential toe region, described with σ = A(eBε −1) followed by a linear elastic region [1]. This has been used to describe the stress-strain properties of many soft tissues [2–4]. Using these traditional models, the two curves are independently fit to a separate set of data points. Thus, it is possible that the two portions of the modeled stress-strain curves do not necessarily exhibit both C0 and C1 continuity, and would not accurately represent a real material.
