The most common cause of knee pain and disability is arthritis.
Osteoarthritis is most common in people over 50 years of age, and in people with a family history of arthritis. In osteoarthritis, the articular cartilage which is cushioning the bones wears away. Eventually the bones will rub against each other causing pain and stiffness.
Everyday activities are being limited due to stiffness and pain. The pain is continuous while resting, at night and during the day. There is little relief from the pain from anti-inflammatory drugs or other treatments such as physical therapy.
Most people who have knee replacement surgery experience a reduction in the amount of pain they are having daily. The majority of patients are able to return to their previous activities with much less pain than before surgery.
The knee is a hinge joint which allows motion at the point where the thigh meets the lower leg. During a total knee replacement, the damaged cartilage and bone will be removed and the new metal and plastic joint surfaces will be placed.