The goal of the present study is to investigate if one of the two dorsal operative procedures (rod-rotation versus translation technique) leads to a better radiographic correction of idiopathic adolescent thoracic scoliosis after operative treatment.

The operative technique in scoliosis surgery introduced by Cotrel and Dubousset attempts to achieve an improvement of the sagittal profile and a derotation of the vertebrae, in addition to a correction of the main curvature of the scoliotic spine by rotation of the convex-side rod (rod-rotation). The technique of segmental correction was described by Luque. Correction of the scoliosis is performed after fixation of each vertebral body with wire cerclages, followed by segmental correction of the deformed spine. The Universal Spinal System was introduced and an operating technique was developed to take advantage of the principle of segmental correction of scoliosis (translation technique).

The radiographic outcomes in two groups comprising a total of 69 adolescent patients treated for idiopathic thoracic scoliosis with dorsal instrumentation by the use of a unified implantation system (Universal Spinal System) were compared retrospectively by an independent observer. In 30 patients an intraoperative correction of the scoliosis was performed by translation technique (translation group) and in 39 patients the correction was achieved by Cotrel-Dubousset instrumentation (rod-rotation group). The mean follow-up interval was 40 months with a minimum of 12 months. The preoperative radiographic measurements of the scoliotic spines showed no significant differences between the two groups.

In both patient groups, the thoracic primary curve, lumbar secondary curve, and apical rotation of the thoracic curve were improved by the operation. The thoracic primary curve was corrected from 50 6° to 24 7° (p< 0.01) in the translation group and from 54 11° to 22 11° (p< 0.01) in the rod-rotation group. The extent of the correction of the thoracic curve was significantly greater in the rod-rotation group than in the translation group (59% versus 52% correction; p< 0.01). Thoracic apical rotation was corrected from 21 ± 9° to 16 ± 10° (p< 0.01) in the rod-rotation group and from 19 ± 9° to 17 ± 7° (p< 0.05) in the translation group. Lumbar apical rotation and the sagittal profile were unchanged in both groups.

Based on the results of this study with a small number of patients, the ability of the translation technique to correct the thoracic major curvature seems to be less than that of the rod-rotation technique. No differences are to be expected in the correction of the lumbar minor curvature or of the rotation of the thoracic apex. Neither procedure is expected to influence the sagittal profile or lumbar rotation.