Use of Nanoindentation to Determine Biphasic Material Properties of Articular Cartilage

Nanoindentation (NI) has been used with increasing frequency to characterize the mechanical properties of biological tissues. However, the majority of prior studies in this area have focused on hard tissues such as bone, enamel, and dentin [1]. For soft, hydrated tissues and biomaterials, methods of analyzing the force-displacement curves to obtain meaningful information on viscoelastic material properties are still under development. In particular, methods for using NI to quantify the biphasic material properties (aggregate modulus H_A, permeability k, Poisson’s ratio ν) of tissues such as articular cartilage have not been established. Such methods could be applied in studies using small animal models to investigate biological and biomechanical mechanisms of articular cartilage degeneration and repair. The overall goal of this study was to develop the use of NI for characterization of the mechanical properties of soft, hydrated materials.