Treatment of failures related to articulation material in THA.  A comprehensive algorithm of surgical options and open questions. 
Total hip arthroplasty is considered one of the greatest advances in health care of the last century.  More than one million THAs are estimated to be performed annually and an increasing number of revisions are expected in the future.  Osteolysis and loosening are still the main reasons for failure, justifying the use of low-wear bearings. The aim of this paper is to describe the mode of failure of the different couplings (polyethylene, cross-linked PE, metal, ceramic) and the options of treatment considering the various scenarios that the surgeon has to face nowadays in the case of failure related to articulation material.  A comprehensive algorithm of treatment strategies is proposed based on the best current evidence and on the authors' experience. Periodical follow-up, indications for early revision, selection of proper surgical techniques and tribology are suggested.  Nowadays, few rules are strongly recommended: trying to avoid any metal in case of failure of metal-on-metal; to avoid metal in fracture of ceramic; never to mix metals or ceramics from different manufactures.  We aim to address a great number of open questions.  There is still need for further research and evidences in this essential field of orthopaedic surgery.