Mineralized tissues at the osteochondral junction in healthy and osteoarthritic joints : advanced microimaging and mechanical studies

Osteoarthritis (OA) is the most common joint disease that causes disability in the adult population. Recent evidence suggests that OA is not a single disease, but a group of diseases that manifest in different clinical phenotypes. The current treatments for OA are limited to nonsteroidal anti-inflammatory drugs, with joint arthroplasty being the only available treatment option at late stages. Although the OA-related changes in articular cartilage and subchondral bone have been extensively studied, the changes in the junction between them remain under-explored.
This study investigated the biochemical composition, mineral crystal structure, the micromechanical and structural properties of the mineralized tissues (i.e., calcified cartilage and subchondral bone plate) at the osteochondral (bone-cartilage) junction in healthy and osteoarthritic knee joints in vitro. Several microimaging modalities were applied to assess tissue-specific biochemical composition, mineral crystal thickness, and microstructure across the junction.
This dissertation provides compelling evidence of compositional, structural, and mechanical alterations in both the calcified cartilage and subchondral bone plate at the osteochondral junction during OA development. In many cases, the changes in calcified cartilage and the underlying bone are different and some of these changes were found to occur at very early stages of degeneration. Thus, this doctoral dissertation proposes that mineralized tissues at the osteochondral junction should be considered separately as vital targets for elucidating the etiology and pathogenesis of OA.