Total ankle replacement removes and then replaces both sides of the ankle joint with specially designed artificial parts, called prostheses. The tibial prosthesis consists of a polyethylene (medical grade plastic) and titanium base plate tray that is inserted into the tibia and fibula, giving the implant a wide base for support. The upper portion of the talus, the bone that moves up and down, is replaced with a component made of cobalt chromium alloy, a metal commonly used in joint replacement prostheses.

One type of ankle prosthesis is made by Depuy Orthopaedics, Inc. of Warsaw, Indiana. The Agility? Total Ankle System design is based on numerous research studies of the structure and mechanics of the ankle joint.

Each artificial ankle prosthesis is made up of two parts:

• The tibial component is the metal portion of the artificial joint that replaces the socket of the ankle (the top portion).
• The talus component replaces the top of the talus. The talus is the first bone of the foot and sits in the mortise of the ankle.

The talus component is made of metal. The tibial component is usually made up of two parts, a metal tray that is attached directly to the bone and a plastic cup that provides the bearing surface. The plastic used is very tough and very slick.

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