Estimating Joint Cartilage Thickness on an Animal Model ex vivo Using Diffuse Reflectance Spectroscopy

A diffuse reflectance visible light spectroscopy method has been developed to estimate bovine cartilage thickness in real time. The system consists of a miniature UV-VIS spectrometer, a halogen tungsten light source, and an optical fiber probe including two 400-μm diameter fibers with a center-to-center separation of 1.2 mm used to acquire the spectra. A total of four patellae were obtained from bovine just after sacrifice. In the study, ten cattle patella cartilage samples were prepared in a cylindrical shape and thinned by a 200-μm step. Spectra were acquired from the 123 cartilage samples. Cartilage samples were divided into training and validation groups. A correlation between the thickness of the cartilage samples and the absorption spectra was obtained using the data of the training group. The relative thickness of the cartilage was estimated with an average error of 15% in the validation group using the correlation. Diffuse reflectance spectroscopy has the potential to estimate the thickness of cartilage lesions during arthroscopic evaluation of knee cartilages.