Wear and osteolysis are still the most important potential problems in total hip and knee arthroplasty. Although technology in arthroplasty has been improved dramatically during the past decade, the clinical data relating to some implants reveal that many concerns remain. During the “Tribology Day� within the scientific programme of the 2013 EFORT Congress in Istanbul, the main topics included these concerns as well as the benefits of the materials most commonly used in total hip and knee arthroplasty. This book includes the presentations delivered on the day and covers a range of interesting issues regarding metal, ceramic, and polyethylene articulations. It provides information on the current concepts relating to tribology in total hip arthroplasty and offers a critical outlook on possible improvements in total knee arthroplasty.