Correction of a scoliotic curve in a spine comprises the steps of implanting an expanding rod isolated completely under the skin and attached to selected portions of the scoliotic curve of the spine at opposing ends of the rod; and producing a controlled force by means of expansion of the rod over at an extended time period under external control until a desire spinal curve is obtained. An incremental force is generated to stretch the scoliotic curve of the spine between the selected portions where attachment of the rod is defined. The controlled force is provided steadily for at least one month or alternatively 1-3 months. Multiple rods may be employed each associated with a different scoliotic curve of the spine or a different portion of the scoliotic curve.