Knee Replacement Knee replacement is a kind of arthroplasty. Arthroplasty literally means “the surgical repair of a joint, ” and it involves the surgical reconstruction and replacement of degenerated joints, using artificial body parts, or prosthetics. When the articular cartilage of the knee becomes damaged or worn, it becomes painful and the knee is hard to move. Instead of sliding over each other, the bones rub and crush together. With a prosthesis, the patient will feel less pain, and the knee will move properly.