In order to understand what a total knee replacement is, it is necessary to understand how a healthy knee
works. The knee is the largest joint in the body. It is classified as a hinge joint and works very much like a common hinge. Your knee is made up of three bones: the femur (thigh bone), the tibia (lower leg bone), and the patella (knee cap). Your knee joint connects the femur to the tibia, and on top of this rests the patella. The patella protects the knee joint and slides in a groove found in your femur when you bend your knee. The muscles around the knee are responsible for supporting and moving your knee. It is extremely important to rebuild and strengthen these muscles before and after surgery.
Unfortunately, as a result of years of working, arthritis, or trauma, a knee can become painful and less functional. Spurs (small pieces of bone) may deposit in the knee and arthritis may wear away the protective lining between the bones causing a painful condition. Conditions that can lead to an unhealthy or painful knee include:
- Rheumatoid arthritis—A chronic disease affecting primarily the lining of the joint resulting in destruction and deformity. The cause of rheumatoid arthritis is unknown.
- Osteoarthritis—Affects the joint surfaces of weight-bearing joints. Although the exact cause is unknown, it is believed to be caused by abnormal wear and tear to the joint surfaces. Other factors that may contribute to osteoarthritis include age, sex, heredity, and obesity. You may eventually lose movement, strength, and function of your knee.
You and your surgeon may make the decision to have your knee replaced with an artificial joint. An artificial knee will function very much like your original knee. Generally speaking, your surgeon will replace the bottom part of the femur and the top of the tibia. In most cases, your surgeon will also decide that your patella needs to be replaced.
Ask your surgeon if you have specific questions about your surgery or the implants used to replace your knee.