1. A device for aiding the selection of a compressive restraint orthosis made of elastic or inelastic material and for evaluating a therapeutic effect upon venous return of the orthosis, and adaptation of the orthosis to morphological characteristic of a limb for which the orthosis is intended, the device comprising means for establishing a first file of data representative of the morphological characteristics of the limb, means for establishing a second file of data representative of the dimensional and rheological characteristics of the orthosis, restraint pressure mapping calculation means adapted to determine, on the basis of the data of the first and second files, restraint pressure values to be exerted by the orthosis at a surface of the limb at a corresponding plurality of predetermined points, means for numerically simulating action of the restraint on hemodynamics of the venous return, adapted to (i) receive as input restraint pressures computed by the mapping calculation means and (ii) deliver values of blood flow rate and/or intravenous pressure at a plurality of points of a numerical model representative of a sural venous network of a limb, and means for presenting the values of blood flow rate and/or intravenous pressure determined by the numerically simulating means, whereby the device evaluates depth-wise therapeutic effect produced by the orthosis upon the venous return.