What is the knee joint? The knee joint consists of the lower leg bone called the tibia or thin bone, the thigh bone called the femur, and the patella, which is flat and garden-shaped. The ends of the bones that make up the joint are covered by a smooth layer called cartilage. Normal cartilage can have almost smooth and painless movement. However, when the cartilage is damaged or becomes diseased due to arthritis, the joint can become stiff and painful. What is an artificial knee joint An artificial knee joint, also known as a knee prosthesis, is made according to the structure, shape and function of the human knee joint. It is surgically implanted to replace a damaged knee joint and restore normal knee function. The artificial knee joint generally consists of two or three parts: a metal femoral component, a hard plastic tibial pad that fits snugly, and a metal tibial buttress component. A malleable bone cement is used to encase the knee prosthesis in the bone. Why do I need a knee replacement? The number one disease requiring knee replacement is arthritis. Arthritis is a disease that causes changes in the structure of the joint. There are different types: 1. degenerative changes (osteoarthritis) 2. hypersensitive reactive arthritis (rheumatoid arthritis) 3. septic arthritis (due to infection) 4. secondary arthritis (gout, hemophilia) inversion deformity of the knee joint 5. traumatic arthritis (joint damage so severe that it cannot be repaired) The result of these diseases is usually pain and limited movement. As the disease progresses, more cartilage is involved, which leads to more destruction of the knee joint. Eventually a knee replacement is needed to resolve the pain and restore function to the knee joint. A number of possible laboratory tests as well as x-rays may reveal this joint pathology. Knee replacement surgery should be considered if other treatments fail to relieve the pain and movement disorders that occur. A patient with arthritis will have the damaged bone and cartilage of the knee removed under anesthesia and replaced with a metal or plastic surface prosthesis to restore motion and function to the knee joint. Optimal age for surgery The age range of indications for surgery has been relaxed as the artificial joint is subjected to more mechanical wear and tear and surgical techniques have improved. Many older patients, as well as many younger patients, are considered candidates for prosthetic joint surgery.