During the 2011 EFORT Congress in Copenhagen, many interesting topics relating to tribology in total hip arthroplasty were discussed during a special day devoted entirely to the subject. EFORT decided that, given the wide interest in these discussions, publication of the presentations would be warmly welcomed by all fellow professionals who were unable to attend. This book is the result. It provides detailed information on currently used articulating materials and their wear performance. Clinical outcomes are discussed, and important new frontiers are carefully considered.