The joint surface is covered by smooth articular cartilage that allows near frictionless movement, shock absorption, and pain-free movement. The cartilage can wear out with age, activity or trauma, leading to osteoarthritis. Other cause may include inflammatory causes such as rheumatoid arthritis or infection -septic arthritis. When the cartilage deteriorates, it becomes rough or disappears entirely leaving the bone surfaces to rub against one another, causing the pain people associate with having arthritis. As the disease advances, the condition can become extremely painful and debilitating affecting quality of life , night sleep and walking distance. When non-surgical methods fail to control pain and improve joint function, a Total or partial knee replacement maybe recommended.