Health budget cuts in developed countries have stressed the importance of the valued physician's activity's representation. Therefore, good codification standards have been necessary. Automated translation from information given directly by the physician is our chosen approach. Through conceptual modeling of nomenclatures used in the domain of Orthopedic Surgery in France, the authors show the feasibility, the advantages and the problems encountered using this kind of modeling with Orthonav, an original knowledge base built for codification of patients' records.