In a fixation system for controlling the alignment of adjacent vertebra after spinal surgery, aligned fixation rods are held in a mount on each of such vertebra, with their juxtaposed ends received in a sleeve between the mounts. At least one of the rods is movable in the sleeve relative to the other to allow controlled movement of adjacent vertebra. In some embodiments, the sleeve can itself be held in a mount installed on one of such vertebra with the aligned fixation rods being capable of relative movement therein. The system allows the spine to grow without the need for further surgery.
