This ETN is timely as it is a response to the highly significant economic and patient issues relating to early failure in metal-on-metal total hip and resurfacing replacements . The media have defined this as a significant public health issue, for instance, the BBC reported Metal-on-Metal hip replacements ‘high failure rate’ , but substantial issues persist with very recent reports of inadequate devices e.g. The Implant Files and FDA guidance [3, 4, 5]. This is a truly European problem with, for instance, new devices manufactured in the UK being first implanted, unsuccessfully, in Belgium, Germany and the Netherlands [6, 7]. The scientific and clinical communities are acutely aware of these detrimental issues and are partaking in a debate which focuses on alternative materials and designs for replacement systems. Furthermore these problems have brought growing concerns from regulatory authorities on how to effectively test new devices, pre-clinically, as the current spate of failures appear not to have been recognised with current standard tests [8, 9]. Learn more about the current state of joint implant research here.