Anterior universal spine system for adolescent idiopathic scoliosis: a follow-up study using scoliometer, real-time ultrasound and radiographs

Abstract

Nine patients with AIS treated surgically with anterior USS instrumentation were examined by several methods pre-operatively and at each of 8 weeks, 1 year and 2 years after surgery (mean age 14.6 years, girls 7, boys 2, thoracolumbar 7, lumbar 1, thoracic 1, left 7, right 2). The methods used were (1) Scoliometer to measure angle of trunk inclinations (ATIs) in the standing forward bending position at each of 10 levels and converted to 18 levels by a computer program, (2) real-time ultrasound in the prone position of laminal rotations at each of 1 8 levels from TI-SI, and (3) anteroposterior radiographs in the standing erect position measured for each of Cobb angle, segmental vertebral rotation (Perdriolle) and segmental vertebral translation from the Ti-Si line (horizontal translation of each vertebral centroid from the T1-S1 line). The findings were plotted graphically and segmentally for each of Scoliometer ATJs, ultrasound laminal rotations, and radiographic vertebral rotations and translations. Findings. Graphical representation of the data shows that the improvement brought about by surgery is most clearly and consistently evident for segmental vertebral translation. The statistical analysis shows that the radiological parameters (Cobb angle, apical vertebral rotation and apical vertebral translation) and ultrasound spinal (laminal) rotation do not change detectably in follow-up. The Scoliometer ATI findings show an increase from 4 degrees (at 8 weeks) to 7 degrees (at 2 years) which is statistically significant. The evidence from this small sample of patients is consistent with the view that the compared with posterior USS, anterior USS surgery for AIS results in (1) similar initial rib hump correction, and (2) less rib hump reassertion during follow-up. More data are needed to evaluate these views.