What is the Delivered Medical Benefit of a device expected to improve the results of a surgical procedure? Could the answer to this question inspire the choice of the information displayed to the surgeon and the design of the interface that will enable him or her to make the best possible use of this information during the surgical procedure? On this basis, would it be possible to detect in real time a discrepancy between a procedure and “good surgical practice”? Computer Assisted Medical Interventions (CAMI) devices begin to significantly be used in the operating theaters, which allows to envisage an original way of answering these questions.