I Teoman BENLI, Serdar AKALIN, Mehmet CITAK, Mert TUZUNER, Mahmut KIS, E Faruk MUMCU


Vertebral rotation in the axial plane is thought to be the primary deformity in the pathogenesis of idiopathic scoliosis. In this study 62 patients with idiopathic scoliosis treated by Cotrel-Dubousset Instrumentation at the 1st Orthopaedics and Traumatology Clinic of Ankara Social Security Hospital from December 1988 to June 1991 were evaluated. Preoperative and postoperative rotation degrees of the apical, intermediate and end-neutral vertebrae of the patients were measured by computed tomography. The maximum amount of correction at the apical vertebra was obtained in King Type III curves in which a derotation manoeuvre had been permormed and RAsag, RAmI and RAdev angles were corrected by 24.8 ± 16.9%, 25.8 ± 18.4% and 26.5 ± 20.8% respectively. This group was followed by King Type IV and Type II curves. Derotational effect was minimal in the lumbar region in King Type I and Type II curves. The highest amount of derotation occurred in the apical vertebrae followed by the intermediate vertebrae and was almost zero at the end vertebrae. It was concluded that the derotational force affected mainly the scoliotic curve and was not carried segmentally to the distal or proximal parts of the vertebral column and did not cause decompensation.