Document WO 2004/061721 shows prior art in the field of the invention. That document describes the creation of a digital model of a patient, that is customized both in geometrical terms and in mechanical terms, for subsequent use in a method of simulating operating strategy, so that prior to an operation, the predictable result can be visualized, thus giving the surgeon the means to assess the effects of a surgical act on the final equilibrium of the patient and on the internal stresses both in the implant and in the anatomical structures.
In the step of constructing the model of the subject, there exists a stage of creating a three-dimensional model as a function of calibrated radiographs of the subject, i.e. radiographs compared with a known point of reference, or a tomographic image of the subject, or any other datum suitable for three-dimensionally reconstituting a customized set of bones. This stage is finished by allocating various general mechanical characteristics to the geometrical reconstitution, which characteristics result from known models forming a kind of standard database applicable to all reconstructed geometries.
The above-mentioned document proposes a method of customizing the mechanical characteristics of the model that is already geometrically customized.
Based on a series of clinical tests carried out on the patient by the surgeon, real geometries are acquired (e.g. by radiography) and the observed displacements relative to a normal posture are interpreted to deduce therefrom mathematical functions governing the behavior of the joint spaces (intervertebral bodies) that satisfy the acquired geometries and do so for each connection between two adjacent vertebrae. That method of proceeding quickly comes up against computation blocks or unsolvable situations because for a vertebral column, there are 17 successive connections between pairs of vertebral bodies to be treated.