Knee replacement surgery, also known as knee arthroplasty, is a medical procedure to replace the damaged or worn-out surfaces of the knee joint with artificial components, called prostheses. This surgery is primarily performed to relieve severe pain and restore mobility in patients suffering from conditions like osteoarthritis, rheumatoid arthritis, or post-traumatic arthritis. Depending on the condition, it can involve total or partial replacement of the knee joint. The procedure is usually recommended when non-surgical treatments such as medications, physical therapy, or lifestyle changes fail to provide relief.