Articular cartilage is biphasic material consisting of solid and liquid, and there is difference in permeability between normal articular cartilage and OA articular cartilage. We can measure water content in specimen nondestructively using NIR spectroscopy. Then we applied NIR spectroscopy to nondestructive testing for physical property of articular cartilages. We deal with the two aspects of the detailed relations between recovery of absorbance and degeneration of human cartilage, that is, 1) relation between the degeneration of human articular cartilage and pattern of absorbance with respect to time after removal of indentation load, 2) relation between the degeneration of human articular cartilage graded by Mankin Score and variation of absorbance with time after removal indentation load. In the most of specimens graded as "normal", the absorbance initial decrease and the subsequent increase. In the specimens of "normal", the Mankin Score was able to be related to the time when absorbance had the minimum value. It is concluded that near infrared spectroscopy enables us to capture the increase of permeability with an increase of damage in articular cartilage.
