The primary cause of osteoarthritis is the gradual wear and tear of cartilage, which is the protective tissue at the ends of bones. This degeneration can be exacerbated by factors such as age, joint injuries, and obesity, which add stress to weight-bearing joints. Genetic predispositions and certain occupations may also contribute to the development of osteoarthritis. As cartilage deteriorates, bones may rub against each other, causing pain, stiffness, and decreased mobility. Maintaining a healthy weight and active lifestyle can help mitigate some of these risks.