Objectives
Despite more than a century of dedicated research, the etiology and pathogenesis of AIS remain unclear. By definition, 'idiopathic' implies an unknown cause. Nevertheless, many abnormalities concomitant to AIS have been described, often with the suggestion that these abnormalities are related to etio-pathogenesis. Insight in the concomitant abnormalities may assist in improving the understanding of the etiological pathways of AIS. For understanding of the etiology of adolescent idiopathic scoliosis (AIS), this systematic review gives as complete an overview as possible of abnormalities that have been implicated to be concomitant with AIS.