Trunk asymmetry and screening for scoliosis: a longitudinal cohort study of pubertal schoolchildren.

A cohort of children was followed-up annually from an average age of 10.8-13.8 years to assess various measures of trunk asymmetry for their predictive value in the screening of scoliosis. Of 1060 children, 855 (80.7%) participated in the final examination. Trunk asymmetry was measured by the forward bending test and moiré topography. A posteroanterior standing radiograph of the spine was taken of those 250 (29.2%) children who had a trunk hump > or = 8 mm. Only 8.3% of the children were found to be symmetric (hump 0-2 mm) in the forward bending test: 65.5% had a hump of 3-7 mm and 26.2% had a hump > or = 8 mm at 13.8 years. Also, moiré fringe asymmetry proved to be common (prevalence of asymmetry > 1 fringe 47.3%), but its correlations with rib hump (r = 0.16) and Cobb angle (r = 0.12) were low. At the final examination, the prevalence of scoliosis (Cobb angle > or = 10 degrees) was 9.2%. Two girls (0.2%) needed brace treatment. The forward bending test is preferable to moiré topography in screening for scoliosis, and a hump size of 6 mm at an average age of 10.8 years is the nearest to optimal as a screening threshold.