The knee joint, as well as other joints in the body, are essentially hinges where two bones meet at a point where they can move with respect to one another. Each bone is covered with a material called articular or hyaline cartilage. This cartilage provides an extremely low friction surface that is incredibly durable. People can live active lifestyles for many decades before this articular cartilage show signs of wear. Knee replacement, or knee arthroplasty, is a procedure to resurface a knee when the articular cartilage is no longer functioning properly. In most cases, the articular cartilage is worn away from arthritis. In some cases, when only part of the knee is worn out, a partial knee replacement can be performed.
Modern knee replacement have been performed since 1968. Since that time, we have learned a great deal about the mechanics of the human knee and have incorporated this knowledge into designing better implants. Advances in material engineering has allowed manufactures to produce implants that wear less and last longer.
Knee replacements are frequently performed as a day procedure or short hospital stay. The procedure is performed the day of admission and therapy is started either the day of surgery or the day after. Some people go to a rehabilitation center after discharge from the hospital while others go directly home. After surgery the person will need to do exercises to gain motion and strength in their knee. When at home, it is important to elevate your leg when recumbent. The person's ability to perform daily activities gradually increases on a weekly basis. Many people return to their jobs between 6 and 12 weeks after surgery.