The invention relates to a method for simulating the behaviour of an articulated bone part assembly, in particular the spine of a subject, that comprises: the step of building a three-dimensional geometric model of the assembly from specific data on the subject in a reference position; the step of mechanically customising the geometric model by particularising at least some articulated linking areas of the bone parts; wherein the mechanical customisation step comprises: a customisation phase of the critical link areas, or junction areas, of the bone parts; a phase for acquiring data concerning the articulated bone part assembly of the subject during at least one clinical test of the posture in a position different from the reference position or of movement from said position; and a phase for characterising the mechanical parameters of said junction areas in order to obtain the reproduction by the model of the data acquired during the above-mentioned clinical test.