From one disease to several diseases: a new approach of the pathophysiology of osteoarthritis

Osteoarthritis (OA) is the most common osteoarticular disease associated with excess mortality due to functional disability. Its physiopathology has made great progress in recent years with a thorough knowledge of the role of each joint tissue, beyond the single involvement of cartilage. The role of each tissue (cartilage, synovium and subchondral bone) and their interactions in the mechanisms of joint degradation has been better understood. Three major clinical phenotypes of OA are clinically defined based on its main risk factors: post-traumatic OA, metabolic OA including obesity-related OA and aging-related OA. Another approach is to study the pathophysiology of OA according to these phenotypes, assuming that each phenotype has pathophysiological specificities. Since these tissue lesions or phenotypes can easily be characterized clinically or by modern imaging methods, we can imagine for the future personalized and targeted treatments resulting from these new pathophysiological data.