Pre-existent rotation of the normal spine at different ages and its consequences for the scoliotic mechanism.

The normal spine is not a symmetrical structure, as has been appreciated for a long time. The reason why the main thoracic vertebrae in idiopathic scoliosis predominantly rotate to the left at the infantile age and to the right at the adolescent age is unclear. We provided an in-depth analysis of the rotational patterns of the normal growing and adult spine in relation to closure of the neurocentral junctions, organ anatomy and the convexity of the curve in idiopathic scoliosis. We believe that the delicate upright human spino-pelvic balance can be disturbed by a multitude of offenses and consequently an idiopathic scoliosis will develop due to the rotational instability. From our results it can be concluded that once this rotation starts to occur, it will naturally follow the pre-existent rotational patterns that we have demonstrated to exist already in the normal spine.