In all the production domains, we usually notice a difference between the user's idea and the designer's proposition product. This variable difference often depends of the design process methodology used by the company. Nowadays, more and more surgical interventions are carried out in Minimally Invasive Surgery, to make the post-operative constraints less painful for the patient. New surgical tools are designed after informal discussions between surgeons and designers. Medical terms, often used by surgeons and employed to explain their needs, don't allow for an instantaneous understanding by designers. Unfortunately, this relation causes a dysfunction in the definition cycle of the product. Our aim is to modify the design process for better understandings and more complementarities between surgeons and designers. For that we have the objective to propose a design methodology which takes the user into account more effectively in the process design. After introducing the "Participatory Design" and the "Scenario-Based Design" methodologies, we will develop a surgeon-centred method-design proposition. Then, we will organise some needs expression scenarios and creativity scenarios to test some surgical tool design solutions.