A knee replacement operation involves exposing the knee joint using an incision over the front of the kneecap. Muscles are then split and dissected.
Once the knee joint has been exposed the cruciate ligaments are divided. Using a saw, damaged portions of the bone ends are removed and the overall alignment of the knee joint is adjusted. Implants are then fixed to the bone ends using cement polymethyl methacrylate, a glassy synthetic resin obtained by polymerising methyl methacrylate. A cobalt chrome cap is placed over the thigh bone and a plastic plate is fixed to the shin bone. The under the surface of the kneecap is replaced with a plastic button.
There are no strings or ties between the shin bone implant and thigh bone implant. Stability depends on muscle tone and collateral ligaments along the side of the knee joint.