Osteoarthritis (OA), also known as degenerative arthritis or degenerative joint disease is a group of mechanical abnormalities that involves degradation of the joint, including the articular cartilage and the subchondral bone. The symptoms can include joint pain, tenderness, stiffness, locking, and sometimes liquid diffusion in the hinge region. A variety of causes, hereditary, developmental, metabolic and mechanical can lead to the loss of cartilage. When bone surfaces are not sufficiently protected due to the loss of cartilage, bone may be exposed and destroyed. As a result of reduced mobility due to pain, regional muscles may atrophy and ligaments may become more lax. Treatment generally involves a combination of exercise, change of lifestyle and use of analgesics.