Osteoarthritis is a common articular cartilage degenerative disease and the main cause is mechanical instability. The mechanical instability can reduce the number of chondrocytes and destroy extracellular matrix through direct injury, inducing cell apoptosis, and stimulating the production of inflammatory factors, leading to decrease of matrix type II collagen and proteoglycan and degeneration of cartilage. Long-term cartilage degeneration can result in osteoarthritis. Therefore, understanding how mechanical instability leads to the incidence of osteoarthritis can better improve the course of osteoarthritis from the perspective of mechanics.