Biomechanical spinal growth modulation and progressive adolescent scoliosis – a test of the 'vicious cycle' pathogenetic hypothesis: Summary of an electronic focus group debate of the IBSE

In the absence of any generally accepted scientific theory for the etiology of idiopathic scoliosis, treatment remains pragmatic with a very incomplete scientific basis. The International Federated Body on Scoliosis Etiology (IBSE) [1] introduced the Electronic Focus Group (EFG) as a means of increasing debate of knowledge on important topics. The text for this debate was written by Dr Ian Stokes who addresses the concept of mechanical modulation of vertebral body growth in the pathogenesis of progressive adolescent scoliosis generally attributed to the Hueter-Volkmann or Delpech effect [1-25] in which constant pathologic strong pressure inhibits endochondral longitudinal growth while reduced compression accelerates growth [2-4]; pressure exerted eccentrically causes an active change in the direction of growth [2,5-7]. Brace treatment is based on this effect although the efficacy of bracing continues to be debated and questioned [26-39] while exercises are not even considered by many clinicians. Guidelines for the conservative management of scoliosis by physical therapy, intensive rehabilitation and brace treatment have been published recently [37,38]; on evidence-based medicine [40,41] bracing and exercises gave a grade of evidence C (level of evidence IV)[37] (i.e. expert committee reports or opinions and/or clinical experience of respected authorities indicating that directly applicable clinical studies of good quality are absent). Since it is generally recognized that multi-level arthrodesis of the spine is not a desirable outcome, currently there is renewed interest in modifying vertebral growth by early surgical interventions [42-44] including stapling and, in young children, fusionless scoliosis surgery [45] which is being evaluated experimentally in animals [46-48].The mechanical modulation of vertebral growth in the presumed asymmetrically loaded spine with scoliosis was described by Stokes as a 'vicious cycle' and interpreted by his vicious cycle hypothesi