Osteoarthritis primarily affects the joints, particularly those that bear weight, such as the knees, hips, and spine. This degenerative condition leads to the breakdown of cartilage and can cause pain, stiffness, and decreased mobility. It is commonly associated with aging but can also result from joint injuries, obesity, and repetitive stress on joints. Individuals experiencing osteoarthritis often have difficulty with daily activities and may seek various treatments, including physical therapy and lifestyle modifications, to manage symptoms and improve joint function.