Abstract
Joint cartilage thickness has been estimated using spatially resolved steady-state reflectance spectroscopy noninvasively
and in-real time. The system consists of a miniature UV-VIS spectrometer, a halogen tungsten light source, and an
optical fiber probe with six 400 um diameter fibers. The first fiber was used to deliver the light to the cartilage and the
other five were used to detect back-reflected diffused light. Distances from the detector fibers to the source fiber were
0.8 mm, 1.6 mm, 2.4 mm, 3.2 mm and 4 mm. Spectra of back-reflected diffused light were taken on 40 bovine patella
cartilages. The samples were grouped into four; the first group was the control group with undamaged cartilages, in the
2nd, 3rd and 4th groups cartilage thickness was reduced approximately 25%, 50% and 100%, respectively. A correlation
between cartilage thicknesses and hemoglobin absorption of light in the wavelength range of 500 nm- 600 nm for source-detector
pairs was found. The proposed system with an optical fiber probe less than 4 mm in diameter has the potential
for cartilage thickness assessment through an arthroscopy channel in real-time without damaging the cartilage.
