Approximately 800,000 hip operations are performed annually in Europe. In 56% of these operations, the components, in particular the cup, are not aligned correctly; this misalignment alters the biomechanics of the system, such that excessive wear of the cup occurs. The subsequent reduction in implant lifespan will affect ~450,000 European citizens, an average of 30,000 per year. In financial terms, the annual cost to European healthcare institutes is in the region of €426m euros, in addition to the increased likelihood of re-revision and associated aftercare costs.There are two types of navigation system currently on the market: (1) Image based which uses CT data to generate 3D preoperative images, and (2) Image-free systems which rely on kinematic data or point-clouds acquired intra-operatively to generate a 3D reconstruction that can be explored during the operation on a computer screen. Both systems have demonstrated improved accuracy over manual surgery. However, current systems entail a large initial cost (~€250K) with high maintenance costs; in addition, most systems take an extra 15 minutes to setup, using valuable theatre time.The D2Eye project will develop a simple to use, low cost, fully mobile guidance system with reduced set up time. The guidance system will allow the surgeon to position the cup accurately allowing for optimum range of movement and as a result will prevent premature failure of the implant normally associated with misalignment. This will be done using a series of electronic orientation units built in to the surgical instruments which will give their position in free space. The information from the units will be projected in front of the surgeon’s eye in real time, allowing them to identify the correct cup implantation position; such a system will enable implant lifetimes to be extended beyond the current average 15 year lifespan, significantly reducing the burden on the healthcare system.