In recent years the 'Tribology Day' has become a recognized highlight of the EFORT Congress, and at the 2012 Congress in Berlin an entire day was once again devoted to tribology in total hip arthroplasty. EFORT decided that, given the wide interest in tribology, publication of the presentations would be warmly welcomed by fellow professionals who were unable to attend. The resulting book includes all presentations delivered on the day and covers a range of interesting topics. Up-to-date information is provided on the various articulating materials, and all the articulations recently used in total hip arthroplasty are discussed, with provision of clinical data. The book will be of interest not only to experienced surgeons but also to trainees and residents who wish to extend their knowledge of total hip arthroplasty._