 Osteoarthritis is the leading cause of chronic disability in the United States.1 It affects about 8 million people in the United Kingdom and nearly 27 million people in the United States, most of whom are over the age of 45. A number of studies have shown that there is a greater prevalence of the disease between siblings and especially identical twins, indicating a hereditary basis 2. Up to 60 of OA cases are thought to result from genetic factors. Other factors causing OA are congenital disorders of joints, diabetes, inflammatory diseases and all chronic forms of arthritis. In addition, injury to joints as a result of an accident, septic arthritis, Marfan syndrome, obesity, ligamentous deterioration or instability may also be factors. 