Three-dimensional Effects of Bracing in Adolescent Idiopathic Scoliosis
Condition: Adolescent Idiopathic Scoliosis
MeSH terms: Scoliosis
Study type: Observational

Summary: 
      This study intends to investigate the three dimensional (3D) effect of bracing on the
      adolescent idiopathic scoliosis (AIS). In particular, it will look at the relationship
      between frontal deformity correction and changes in the sagittal profile and apical vertebral
      rotation (AVR) during bracing. The investigators hypothesise that if the thoracic frontal
      deformity can be controlled with bracing, there will be spontaneous correction of the
      sagittal plane and rotation deformity through coupling.
    

Detailed description: 
      Scoliosis is a 3D deformity of the spine with curvatures occurring in three planes.

      The efficacy of bracing in correcting the frontal deformity is now well-accepted after the
      Bracing in Adolescent Idiopathic Scoliosis Trial (BRAIST). Restoration of the sagittal
      alignment is one of the fundamental goals in scoliosis treatment. The investigators have
      previously demonstrated on fulcrum bending radiographs that there is coupling between the
      frontal deformity, thoracic kyphosis and apical vertebral derotation. The investigators'
      findings suggest that there may be natural coupling of the frontal and sagittal deformities
      towards "self-normalisation" during correction of the curves. The effect of bracing on the
      sagittal alignment and 3D deformity in scoliosis is currently not well-understood. If there
      is a tendency for the natural curve behaviour to return towards a more normal sagittal
      alignment, then bracing may exert a similar effect on the 3D profile. Understanding how the
      3D deformity is affected by bracing allows further insight into curve progression and brace
      effectiveness.

      Few studies in the literature have addressed the sagittal profile and 3D correction by
      bracing. Of those, the findings were based on vertebral reconstructions obtained from
      CT-scan, finite element analysis modelling, or studying the changes in the rib cage rotation.
      However, the investigators propose to measure the 3D profile using the modern EOS ® system,
      which allows biplanar radiography and 3D calculations and a more accurate measurement of
      vertebral wedging.
    

Intervention name(s): EOS X-rays
Intervention type(s): Radiation
Intervention description(s): Full length, orthogonal anteroposterior and lateral X-rays will be taken simultaneously in a standardised standing position, with arms folded anteriorly in 45 degrees . All radiographs will include C7 proximally and the femoral heads distally. 3D reconstruction of the spine can be performed. X-rays will be repeated after the brace is applied, and at intervals of no fewer than 6 months until the brace is weaned off, or if surgical intervention is required. Coronal, sagittal and axial parameters will be calculated from the reconstruction. 3D vertebral wedging will be calculated in the posterofrontal, sagittal and diagonal planes at the apex, 3 superior and 3 inferior vertebrae, as described by Scherrer et al. Changes in the pre- and post-bracing and follow-up parameters can be calculated.
Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The study will be conducted in the Department of Orthopaedics and Traumatology, The
        University of Hong Kong.
      
Keywords: AIS