Quality evaluation in the field of Augmented Surgery is strategic for public health policies. It implies to be able to effectively perform evaluation of Quality in term of Expected Medical Benefit (EMB). The notion of EMB is complex and not standardized in this field. To define and to evaluate EMB, it is necessary to discover the knowledge on the domain targeted by the device and to structure it. This paper presents first parts of this work. Focused on navigated knee surgery, it led us to obtain two main results: the identification of a new criterion for evaluating EMB obtained thanks to the formalization of a new kind of metadata. These encouraging results seem to offer new perspectives for the evaluation of devices from the field of augmented surgery.