Thanks to their flexible elastomer support, those spines can be used for distraction and cage placement, or, in the case of the RDEP & SDEP (see the "Scoliosis Model/Deviated spine" section), correction of deformities with screws and rods.
Be careful: the spines cannot be removed from their elastomer support. This indivisibility ensures a better stability during workshops, and a great longevity, as the elastomer will come back to its initial position once you have finished to work on it, allowing you to restart the same demonstration again and again.