Influence of structure and composition on dynamic viscoelastic property of cartilaginous tissue: Criteria for classification between hyaline cartilage and fibrocartilage based on mechanical function

Recently, many types of methodologies have been developed to regenerate articular cartilage. It is important to assess whether the reconstructed cartilaginous tissue has the appropriate mechanical functions to qualify as hyaline (articular) cartilage. In some cases, the reconstructed tissue may become fibrocartilage and not hyaline cartilage. In this study, we determined the dynamic viscoelastic properties of these two types of cartilage by using compression and shear tests, respectively. Hyaline cartilage specimens were harvested from the articular surface of bovine knee joints and fibrocartilage specimens were harvested from the meniscus tissue of the same. The results of this study revealed that the compressive energy dissipation of hyaline cartilage showed a strong dependence on testing frequency at low frequencies, while that of fibrocartilage did not. Therefore, the compressive energy dissipation that is indicated by the loss tangent could become the criterion for the in vitro assessment of the mechanical function of regenerated cartilage.