Spinal mobility and posture in adolescent idiopathic scoliosis at three stages of curve magnitude.

Spinal posture and mobility were studied in 71 girls with progressive adolescent idiopathic thoracic scoliosis. Measurements were carried out by inclinometers and a compass in three planes; sagittal, frontal, and horizontal. The patients were divided into three groups according to the curve magnitude. Group 1 had curves smaller than 25 degrees, group 2 had curves between 25 and 35 degrees, and group 3 had curves greater than 35 degrees. The positional inclines of sacrum, upper lumbar and upper thoracic areas became more vertical as the curve size increased resulting in smaller lumbar lordosis and thoracic kyphosis. In the thoracic spine flexion and bending to the right was smaller in group 3 than in the other groups. Rotations in both clockwise and counterclockwise directions decreased as the curve size increased. In the lumbar spine only bending to the left decreased significantly with the curve size increase. All thoracic and lumbar movements except lumbar rotations had a general tendency to stiffening as the curve size increased. Of the mobility measurements thoracic rotation most clearly decreased with increased curves, which together with straightening of the spine can be important features in the pathomechanism of a progressive idiopathic thoracic curve.