A Posterior Dynamic Stabilization (PDS) device that regulates physiologic spinal elongation and compression. Regulation of elongation and compression are critical requirements of Posterior Dynamic Stabilization devices. Elongation and compression of the device allow the pedicles to travel naturally as the spine flexes and extends. This interpedicular travel preserves a more natural center of rotation unlike some conventional PDS devices that simply allow bending. The device incorporates two components: 1) a spring that allows elongation/compression, and 2) a polymer core component that serves to increase the stiffness of the device in shear, bending, and tension, and also prevents soft tissue ingrowth.