Knee replacement procedures are surgeries that remove part or all of a damaged or diseased knee joint, replacing it with a prosthetic, or artificial, joint. These procedures are the most common form of joint replacement surgery and are performed in approximately 600,000 patients every year in the United States. So why do so many people need knee replacement? Here we'll look into what conditions commonly lead to knee replacement surgery and a number of facts and statistics about these procedures that may be helpful to those considering a means of treatment.