Osteoarthritis involves the progressive degeneration of the cartilage surface, which leads to joint pain and dysfunction. Arthroscopy is the standard procedure for monitoring cartilage degeneration in situ. However, this evaluation depends on the surgeon's subjective interpretation, and therefore may lack reliability. Full-field optical coherence tomography (FFOCT) is a promising technique that could enable micrometer scale cartilage evaluation in situ.
A preliminary study was carried out by the Grenoble-Alpes University Hospital in collaboration with TIMC-IMAG laboratory and LLTech to evaluate the ability of the FFOCT microscope commercialized by LLTech to evaluate cartilage quality. FFOCT images were acquired and matching histology sections were prepared for 33 ex vivo cartilage samples. A strong and significant correlation was found between the histology and FFOCT evaluation of the cartilage quality, both qualitatively and quantitatively.
In order to use FFOCT for the evaluation of cartilage quality at the micrometer scale in situ, LLTech has developed an endomicroscope version of the FFOCT microscope. When held in contact with the tissue to image, the FFOCT rigid endomicroscope acquires a micron resolution virtual optical slice at a depth of 20 microns below the surface, showing the tissue architecture at this depth in an 'en face' view of 1 mm diameter.
This FFOCT endomicroscope has been assessed through images that have been acquired of fresh ex vivo human cartilage samples using both the microscope and endomicroscope. Chondrocytes have been identified in both the microscope and endomicroscope images. Furthermore, a localization environment is under development by the TIMC-IMAG laboratory in order to be able to track the movement of the endomicroscope such that multiple endomicroscope images can be mosaicked together.