|Osteoarthritis (OA) of the knee joint is a common cause of disability, especially among the elderly population where it is the most prevalent co morbidity to result in functional disability. Primary OA of the knee is, by definition an idiopathic disease that occurs without any known initiating factor. Current evidence would suggest there is a hereditary predisposition to OA of the knee. However, this would seem to be multifactorial and the development of OA in the knee may depend upon multiple genetic factors, not only of those relating to cartilage degeneration but also of those relating to the morphology of the knee joint, both of which seem to be influenced by similar genes. These genes that affect the joint structure may be expressed in cartilage, meniscus, tendons, fat pads or any other joint tissue, and consequently may be involved in the development of OA of the knee. Knowledge of the genes that affect the initiation and/or progression of knee OA are important for development of new treatment options at an early stage of the disease preventing future physical disability.