Is osteoarthritis a disease involving only cartilage or other articular tissues?

Osteoarthritis (OA) is a progressive and disabling disease resulting from a combination of risk factors, including advancing age, genetics, trauma, knee malalignment, increased biomechanical loading of joints through obesity, augmented bone density and an imbalance in physiological processes resulting in catabolic cascades on a molecular level. This review will highlight the involvement early in the disease process of not only the cartilage but also the synovial membrane and subchondral bone and the pathophysiological mechanisms of each of these tissues that lead to joint degeneration. We will summarize the current pathological mechanisms that occur in the abovementioned articular tissues, and briefly discuss their interconnections during OA.