Microindentation test for assessing the mechanical properties of cartilaginous tissues

Mechanical properties of the fresh control, frozen, and vitrified cartilaginous (cartilage and meniscus) samples were measured by microindentation. Indentation depth, elastic modulus, and indentation yield strength were obtained from the microindentation loading curves. Indentation deformation behavior was studied using Hertz contact model. The stress distribution of cartilaginous tissues under indentation loading was analyzed by finite element technique. It was found that fresh tissue shows the lowest indentation depth and the highest elastic modulus and indentation yield strength, followed by vitrified and frozen tissues. The vitrified tissue shows slightly lower but comparable mechanical properties with control tissue. The vitrification technique used in this study can preserve live cells with superior mechanical properties that make it an ideal technique for use in orthopedic and other biomedical applications. The microindentation tests and corresponding analysis methods used in this study offer a simple way to evaluate the mechanical properties of cartilaginous tissues. It suits small sample sizes and it may be used for other biological tissues.