This study includes the design and testing of a program that creates quadric-based geometric models of the trabecular region, designed specifically for use with the 2005 version of the Monte Carlo radiation transport code PENELOPE. Our model was tested, by comparison with published data, in two aspects: the distributions of path lengths throughout the geometry and absorbed fraction values from the monoenergetic emission of electrons from within our geometry. In both comparisons, our results show a close agreement with published methods.