Osteoarthritis year 2012 in review: biology.

This review focuses on recent findings in pathobiology of osteoarthritis (OA). The progress in this field will be illustrated based on three questions; 1. What factors maintain or alter the articular chondrocyte phenotype? 2. What is the role of inflammation in OA? 3. Is there a role for aging-related genes in OA? Recent findings make it more and more obvious that OA is not a single tissue disease, but that development and progression of OA is the resulted of an integrated complex of local and systemic factors that contribute to the pathobiology of this widespread disease.