Classification of Spinal Deformities Using a Parametric Torsion Estimator

  • Jesse Shen
  • Stefan Parent
  • Samuel KadouryEmail author
Conference paper
Part of the Lecture Notes in Computational Vision and Biomechanics book series (LNCVB, volume 17)


Adolescent idiopathic scoliosis (AIS) is a 3D deformity of the spine. However, the most widely accepted and used classification systems still rely on the 2D aspects of X-rays. Yet, a 3D classification of AIS remains elusive as there is no widely accepted 3D parameter in the clinical practice. The goal of this work is to propose a true 3D parameter that quantifies the torsion in thoracic AIS and automatically classifies patients in appropriate 3D sub-groups based on their diagnostic biplanar X-rays. First, an image-based approach anchored on prior statistical distributions is used to reconstruct the spine in 3D from biplanar X-rays. Geometric torsion measuring the twisting effect of the spine is then estimated using a novel technique that approximates local arc-lengths with parametric curve fitting at the neutral vertebra in the thoracolumbar/lumbar segment. We evaluated the method with a case series analysis of 255 patients with thoracic spine deformations recruited at our institution. The torsion index was evaluated in the thoracolumbar/lumbar junction in 3 sub-groups stratified by their lumbar modifier. An improvement in torsion estimation stability (\(\mathrm{mm }^{-1}\)) was observed in comparison to a previous approach. An automatic classification based on torsion indices identified two groups: one with high torsion values (\(2.81\,\mathrm{mm }^{-1}\)) and one with low torsion values (\(0.60\,\mathrm{mm }^{-1}\)), showing the existence of two sub-groups of 3D deformations stemming from the same 2Dclass.


Adolescent Idiopathic Scoliosis Cobb Angle Spinal Curve Apical Vertebra Scoliotic Spine 
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Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  1. 1.CHU Sainte-Justine Research CenterMontréalCanada
  2. 2.CHU Sainte-Justine Research Center, Department of SurgeryUniversité de MontréalMontréalCanada
  3. 3.CHU Sainte-Justine Research Center, MEDICALÉcole Polytechnique de MontréalMontréalCanada

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