Osteoarthritis (OA), the most common form of arthritis, is characterized by degradation and loss of articular cartilage, hypertrophic bone changes with osteophyte formation, subchondral bone remodeling, and inflammation of the synovial membrane. This disease can be triggered by endogenous predisposing factors (e.g., age, gender, high body mass index, genetics) and external factors (e.g., trauma). OA engenders pain and disability, which could result in joint replacement. Currently, treatment only relieves symptoms. However, important advances have been made in understanding its pathological processes, and promising disease-modifying OA drugs (DMOADs) are being developed that will slow the progression of the disease and improve its outcome.