(i) Why do total hip replacements fail?

Total hip replacement (THR) is one of the most commonly performed elective orthopaedic procedures in the UK and is also recognised to be the single most successful operative intervention in modern medicine. Total hip replacements are increasingly used in younger and more active patients. With increasing demand, a clear understanding of how THRs fail is critical in order for us to minimise future complications and optimise our interventions. For the purpose of this article, failing THRs are defined by the need for revision surgery. Revision THR procedures are associated with increased complications including high perioperative mortality and morbidity, as well as financial costs to patients and the National Healthcare Service. Many factors influence the success of primary THRs; these include: 1) Patient factors; 2) Surgical technique; and 3) Implant factors. We discuss current concepts in optimising these features with the aim of prolonging THR survivorship and patient satisfaction.