Problems with diagnosing early stadia of scoliosis due to discrepancies between ATR and the Cobb angle

Abstract

Background This research analysed discrepancies between the angle of trunk rotation (ATR) and the Cobb angle, in order to study if the commonly used 7° cut-off threshold for ATR helps diagnose scoliosis. In early stadia of scoliosis in children, ATR and the Cobb angle often disagree, increasing the risk of a false diagnosis: while the former does not suggest scoliosis, the latter does. Methods The study analysed ATR clinical parameters and the Cobb angle in the X-ray pictures of 117 (23 boys and 94 girls, aged 6–17 years) children who had not yet started treatment and whose X-ray pictures showed the Cobb angle of at least 10°, indicating idiopathic scoliosis. The degrees of lumbar lordosis and thoracic kyphosis were measured using the Saunders inclinometer, and back asymmetry was measured with Adam’s forward bend test using the Bunnell scoliometer. In the X-ray pictures, the curvature angle was plotted according to the Cobb method. The patients were stratified based on their age, and their ATRs and Cobb angles were compared. Results Although all the children had the Cobb angle over 10°, in 69 out of 117 (59%), ATR was below 7%. So, using the 7° cut-off threshold rule, scoliosis would not be diagnosed in those children. This shows that the two tests often disagree, suggesting that the 7° cut-off threshold or ATR is ineffective in diagnosing scoliosis. Conclusions To improve the method for diagnosing scoliosis based on ATR, consideration should be given to lowering the 7° ATR cut-off threshold.