OS7-2-6 Application of near infrared spectroscopy to determination of water content in articular cartilage

Abstract

This paper deals with an application of the near infrared (NIR) spectroscopy to quantitative measurement of the water content in human articular cartilage under compressive loading and unloading. Indentation test on human articular cartilage, and the subsequent measurement of the NIR absorbance at the wave length of 1.46 μm have been performed. Difference in time dependent recovery of the NIR absorbance between the normal and degenerated articular cartilage were investigated. The degenerated articular cartilage showed relatively high Mankin (MK) score, an index of cartilage degeneration, and the rapid recovery of the NIR absorbance, while low MK score and slow recovery of the NIR absorbance were observed in the normal articular cartilage. The relations between the NIR absorbance and water content, the NIR absorbance and thickness, and the NIR absorbance and water content per unit thickness were established. The cartilage showed no correlation between the NIR absorbance and water content, but showed the NIR absorbance was in proportion to water content per unit cartilage thickness. Linear relation between thickness and the NIR absorbance was found as well. From these results, water content in human articular cartilage was able to be formulated as a function of the NIR absorbance. It is concluded that non-destructive, low-invasive and quantitative estimation of water content in human articular cartilage can be performed using the NIR spectroscopy.