A surgical implant for fixation of the human spinal column in the treatment of scoliosis, particular in very young children. The device comprises a pair of elongate bars which are rigidly connected together to form a generally rectangular appliance, and wherein the lower portion of the device is slidably connected to the upper portion so that the device is capable of extension and contraction in the longitudinal direction. In the particular embodiment disclosed, the lower fixation element is formed as a pair of sleeves connected together by a cross member with the free end portions of the bars slidably received within the sleeves thereby permitting the aforementioned longitudinal extension. The device is implanted on the posterior side of the spinal column with the bars and sleeves wired to individual vertebrae to thereby stabilize the spinal column and prevent it from reassuming the prior scoliotic curve. The fact the the device is extensible in the longitudinal direction permits the device to extend with the growth of the spine thereby preventing trunk shortening, which is a problem with other appliances used for treatment of scoliosis.