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.
The other advantage of this durable flexibility is the realistic sensation of "resistance", bringing to mind the efforts that are necesary to distract or reorient a spine with all the tissues around.