Trunk rotation in scoliosis. The influence of curve type and direction in 150 children.

We compared the angle of trunk rotation (ATR) from scoliometer readings with Cobb angle measurements of the lateral deviation of the spine in 150 children referred to hospital for evaluation of scoliosis. The mean Cobb angle in thoracic curves was 16 degrees. In thoracolumbar curves 17 degrees and in lumbar curves 20 degrees. In thoracic curves and in right convex curves no patient with a Cobb angle of 25 degrees or more had an ATR below 9 degrees. In thoracolumbar and lumbar and in left convex curves, 7 degrees ATR was occasionally associated with scoliosis of 25 degrees or more. The correlation coefficient between the ATR and Cobb angle in right convex curves was 0.65 compared to 0.57 in left convex curves. We conclude that a criterion of > 7 degrees ATR for thoracic or right convex curves and one of > 6 degrees ATR for thoracolumbar and lumbar or left convex curves seem adequate for identification of patients with Cobb angles of 25 degrees or more, which reduces the need for spinal radiography and follow-up outside the school screening programs.