Chronic low back pain is common and a leading cause of disability. Weight loss can potentially prevent the need for knee replacement surgery in people with knee osteoarthritis. Being overweight or obese is known to increase your chances for developing osteoarthritis and it makes symptoms even worse for people who already have it. A sudden knee injury can tear the meniscus, a C-shaped piece of cartilage between the thighbone and shinbone. Meniscal tears also may occur simply as a result of aging because the cartilage can become brittle over time (called degenerative meniscal tears).