The knee is a simple hinge-type joint that is responsible for bending and extending the lower leg. This joint allows us to carry out everyday functions such as walking and running, in addition to high-level activities such as kicking, jumping and swimming. Arthritis in the knee is common because of the years of weight-bearing stress and strain placed on it. According to the American Academy of Orthopedic Surgeons (AAOS), 581,000 knee replacements are performed each year in the U.S due to trauma or severe arthritis. Parts of the knee include the femur, tibia and patella bones.
Femur
The femur is known as your upper leg, or thighbone. This is the largest bone in your body and forms the upper portion of your knee joint. According to eOrthopod.com, the end of the femur meets the top of the tibia (shinbone) to form the knee. The bottom portion of the femur has two round knobs called femoral condyles. These condyles meet the top surface of the tibia, and work together to create the hinge movement of the knee. Your femoral condyles commonly become arthritic over years of wear and tear. In a knee replacement, this portion of the knee will be removed and replaced with artificial femoral condyles.
Tibia
The tibia is the lower leg, or the shinbone. The top of the tibia meets the bottom of the femur to form the knee joint. The top of the tibia is called the tibial plateau and meets with the femoral condyles to create a hinge movement of the knee joint. The inner half of the tibial plateau is called the medial tibial plateau and the outside half is called the lateral tibial plateau. Similar to the femoral condyles, arthritis can affect the tibial plateau as well. During knee replacement surgery, this part of the tibial will be removed and replaced with an artificial tibial plateau.
Patella
The patella, or kneecap, provides protection from anterior trauma to the knee joint. In addition, the patella helps to guide the quadriceps (thigh muscle) tendon to the tibia. The patella also moves during leg extension in a groove called the patellofemoral groove. Arthritis can also affect the patella and cause pain during leg extension. This bone may or may not be replaced during knee replacement surgery, depending on the health of the bone.
