Polyethylene is the material that makes up the tibial and patellar components of a knee implant. Polyethylene is important because it enables the articulation, or joint, of the implant components.On the tibia, the polyethylene sits on a metal platform and acts as the cushion between the tibia and femur. Polyethylene wear is one of the most common reasons for revision surgery. ConforMIS knee replacement systems are designed to reduce the risk of polyethylene wear: Engineered for low contact stress throughout the range of motion The latest proven material technology for stronger and more durable polyethylene inserts