Near-Infrared Spectroscopy Enables Arthroscopic Histologic Grading of Human Knee Articular Cartilage

Ultraviolet-Visible-Near Infrared Spectroscopy May Aid in the Qualitative Assessment of Early-Stage Cartilage Degradation

Purpose

To assess the potential of ultraviolet-visible near-infrared spectroscopy to provide quantitative information on the cartilage surface at early osteoarthritis.

Methods

We used a similar source and optical path to a standard arthroscope and constraining input to the range available to a standard detector/camera, further capturing and analyzing spectral information quantitatively in terms of specific electronic absorbance bands and scattering from the cartilage surface, with a focus on the early stages of degradation.

Results

The ratio of the 320-nm and longer than 500-nm absorbances produced a distinct change from the normal to diseased states. The slopes between the wavelengths of 600 and 980 nm may show the transition of the single fibril to fibril bundles that occurs during early stages disease.

Conclusions

Ultraviolet-visible near-infrared spectroscopy has good potential for use in integrated arthroscopic assessment.

Clinical Relevance

This raises the possibility of advancing arthroscopy from a qualitative to a quantitative tool, without requiring modification of either the radiation (the light source and path) or instrumentation (the arthroscope itself) delivered to the patient, thus allowing a low-cost yet potentially high-value technology.

Diffuse reflectance spectroscopy of the cartilage tissue in the fourth optical window

Studies of the optical properties of biological tissues in the infrared range have demonstrated significant potential for diagnostic tasks. One of the insufficiently explored ranges for diagnostic problems at the moment is the fourth transparency window, or short wavelength infrared region II (SWIR II). A Cr²⁺:ZnSe laser with tuning capability in the range from 2.1 to 2.4 µm was developed to explore the possibilities in this region. The capability of diffuse reflectance spectroscopy to analyze water and collagen content in biosamples was investigated using the optical gelatin phantoms and the cartilage tissue samples during their drying process. It was demonstrated that decomposition components of the optical density spectra correlated with the partial content of the collagen and water in the samples. The present study indicates the possibility of using this spectral range for the development of diagnostic methods, in particular, for observation of the changes in the content of cartilage tissue components in degenerative diseases such as osteoarthritis.