Abstract: Growing rod systems and methods for correcting spinal deformities include at least one growing rod assembly and at least one fluid delivery assembly. Each growing rod assembly includes a fluid actuator that is operable to extend first and second rod segments in opposite directions along the spine. The fluid actuator can be provided by, for example, a piston-cylinder actuator. Each fluid delivery assembly includes a fluid pump operably connectable to a fluid line, which in turn is connected to the fluid actuator. In one embodiment, the fluid actuator is of a linear design. In another embodiment, two linear or curvilinear fluid actuators are provided back-to-back and connected by a connecting rod that mounts to the mid-spine and is contourable. In another embodiment, the fluid actuator is of a curvilinear design to generally conform the normal spine. And in another embodiment, the fluid actuator includes a fluid-over-fluid shock absorber.