A system and method for ameliorating spinal column anomalies, such as scoliosis, includes bone screws which are to be implanted in the pedicle region(s) of individual to-be-derotated vertebrae and in vertebrae to which balancing forces must be applied as the spinal column is manipulated en mass to achieve an over-all correction of the condition. A pedicle screw cluster derotation tool simultaneously engages multiple pedicle screws and transmits manipulative forces to multiple vertebrae to effect a whole-spine correction. Pre-contoured spinal rods are engaged post-derotation to secure the correction.