Total knee replacement is one of the most common orthopedic procedures performed in the United States. The most common indication for total knee replacement is osteoarthritis. Clinical signs of knee osteoarthritis include pain with walking, difficulty ranging the knee, knee instability, varus deformity, bony enlargement, extension lag, and flexion contracture. Radiologic evidence for osteoarthritis of the knee includes the presence of osteophytes, joint space narrowing, subchondral sclerosis, subchondral cysts, and malalignment.