Osteoarthritis (OA), also known as degenerative joint disease or hyperostosis, is the most common cause of knee arthritis. Pain, dyskinesia and disability induced by osteoarthritis impact severely on the subject's health and quality of life. Knee osteoarthritis is very common in the elderly population. As life expectancy has increased, the incidence of osteoarthritis rose significantly during the 20th century. For people over 60 years of age, approximately 50% show signs of osteoarthritis on x-rays, among which 35% -50% show clinical signs. For people over the age of 75, 80% had osteoarthritis symptoms.