Selective ventral derotation spondylodesis in idiopathic thoracic scoliosis: A prospective study

Aim: Radiometric curve analysis of instrumented primary and spontaneous secondary curve correction after anterior correction and fusion of idiopathic thoracic scoliosis. Method: Sixty-four patients with idiopathic thoracic scoliosis were prospectively evaluated. All patients were operated either with the Zielke-VDS or with a primary stable double rod instrumentation with selective fusion of the thoracic curve from end-to end-vertebra. Follow-up averaged 29 months (24-52 months). Results: The Cobb angle of the primary curve averaged 63.2degrees preoperatively and was corrected to 21.4degrees postoperatively with an average loss of correction of 5.3degrees (58% final curve correction). Apical thoracic vertebral rotation was corrected by 48%. The secondary lumbar curve measured 38.2degrees preoperatively (72% correction on the bending films) and was spontaneously corrected by 57% to 16.4degrees without significant loss of correction in the final follow-up. Apical vertebral rotation averaged 11.3degrees in the lumbar curve and was corrected spontaneously by 24% to 8.6degrees without significant loss of correction. Lumbar apex vertebra deviation showed no significant reduction. There was no case of lumbar curve decompensation in either frontal or sagittal plane. Implant related complications were observed in 7 patients (rod breakage), but no pseudarthrosis occurred. There were no neurological complications noted. Conclusion: Selective anterior correction and fusion in idiopathic thoracic scoliosis enables a satisfactory correction of both primary and, lumbar secondary curves. The advantage of selective anterior correction and fusion of thoracic scoliosis is the short fusion length, better derotation and satisfactory correction of the secondary lumbar curve. The disadvantages of single threaded rod techniques in terms of lack of primary stability and a kyphogenic effect have been eliminated by the development of a primary stable, small size double rod instrumentation.