A spinal rod includes a rod tube formed of a biocompatible material, a spring rod formed of a biocompatible material and having a spring rod portion disposed in the rod tube, the spring rod portion axially movable within the rod tube whereby application of an axial force on the spring rod portion creates axial movement of the spring rod relative to the rod tube causing the spring rod and the rod tube to flex and arch, and a spacer ring radially disposed between the rod tube and the spring rod.
