title: Evaluation of a Three-Dimensional Reconstruction Method of the Rib Cage of Mild Scoliotic Patients.
abstract: METHODS
  Validation study.
  
  
  OBJECTIVE
  To evaluate a method of 3-dimensional (3D) reconstruction of the rib cage in a population of scoliotic patients.
  
  
  BACKGROUND
  Evaluation of the thoracic cage clinical parameters would be helpful in the management of spinal deformities.
  
  
  METHODS
  Biplanar X-rays were performed using the EOS system and the rib cage was reconstructed using a previously developed semi-automated method. Thoracic parameters were calculated from the 3D reconstructions: volume, frontal and sagittal diameters, 3D spinal penetration index (SPI), thoracic index, and rib hump. To test accuracy, the authors constructed biplanar projections from 3 computed tomography scans and then used these projected X-rays as material for stereoradiographic reconstructions. The models were then compared with volumetric objects reconstructed from these 3 computed tomography scans. To test intra-observer and interobserver reproducibility, 22 chests (mean Cobb angle, 28° [range, 17° to 45°]) were reconstructed twice by 3 operators. The 95% confidence interval was calculated for the study parameters.
  
  
  RESULTS
  The mean signed point to surface distance was -1.6 mm. Interobserver reproducibility was 9 mm for maximum anteroposterior and lateral diameters, <0.8% for SPI, 5° for rib hump, .02 for thoracic index, and 450 cm3for volume.
  
  
  CONCLUSIONS
  The results of the reproducibility study were satisfactory. The 95% confidence interval was <6% for the transverse diameters and <10% for volume and SPI. The reported method of 3D reconstruction of the rib cage provides accurate and reproducible determinations of the investigated thoracic parameters in scoliotic patients.
authors.affiliation: Laboratoire de Biomécanique, Arts et Métiers, ParisTech, 151 Boulevard de l'Hôpital, 75013 Paris, France; Pediatric Orthopedic Department, Grenoble University Hospital, Joseph Fourier University, BP 217 38043 Grenoble Cedex 9, France. Electronic address: aurelien.courvoisier@gmail.com.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Courvoisier
authors.affiliation: Laboratoire de Biomécanique, Arts et Métiers, ParisTech, 151 Boulevard de l'Hôpital, 75013 Paris, France.
authors.forename: Brice
authors.initials: B
authors.lastname: Ilharreborde
authors.affiliation: Laboratoire de Biomécanique, Arts et Métiers, ParisTech, 151 Boulevard de l'Hôpital, 75013 Paris, France.
authors.forename: Barbara
authors.initials: B
authors.lastname: Constantinou
authors.affiliation: Laboratoire de Biomécanique, Arts et Métiers, ParisTech, 151 Boulevard de l'Hôpital, 75013 Paris, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Aubert
authors.affiliation: Pediatric Orthopedic Department, Trousseau Hospital, Paris 6 University, 12 Rue Arnold Netter, 75012 Paris, France.
authors.forename: Raphael
authors.initials: R
authors.lastname: Vialle
authors.affiliation: Laboratoire de Biomécanique, Arts et Métiers, ParisTech, 151 Boulevard de l'Hôpital, 75013 Paris, France.
authors.forename: Wafa
authors.initials: W
authors.lastname: Skalli
keywords: 3D; Rib cage; Scoliosis; Stereoradiography; Volume