title: Functional classification of patients with idiopathic scoliosis assessed by the Quantec system: a discriminant functional analysis to determine patient curve magnitude.
abstract: METHODS
  A stepwise discriminant analysis was used to define a spinal deformity score based on three-dimensional measurements by the Quantec spinal image system (raster stereophotograph).
  
  
  OBJECTIVE
  To provide functional classification of spinal deformity in patients with mild idiopathic scoliosis without using radiographs.
  
  
  BACKGROUND
  Most studies classify the degree of spinal deformity in terms of coronal plane radiograph without analyzing transverse rotation. To the authors' knowledge, no studies investigating classification of spinal deformity in idiopathic scoliosis using Quantec system measurements have been documented.
  
  
  METHODS
  In this study, 129 patients with a single curve and 119 patients with a double curve were divided into three groups according to Cobb angle: Group 1 (less than 10 degrees ), Group 2 (10-20 degrees ), and Group 3 (greater than 20 degrees ).
  
  
  RESULTS
  The patients were assigned to the group with the highest scores after application of a stepwise discriminant analysis. The accuracy of the classification system by functional scores for the patients with a single curve was 85% for Group 1, 63.5% for Group 2, and 71.7% for Group 3. The accuracy of classification by functional scores for the patients with a double curve was 87.1% for Group 2 and 76.1% for Group 3.
  
  
  CONCLUSIONS
  The back surface image study is a method for providing a quantitative assessment of mild spinal deformity, allowing evaluation of patients by integrated three-dimensional parameters with no reference to radiographs.
authors.affiliation: Department of Orthopaedic Surgery, Medical College of Wisconsin, Milwaukee, USA.
authors.forename: X C
authors.initials: XC
authors.lastname: Liu
authors.forename: J G
authors.initials: JG
authors.lastname: Thometz
authors.forename: R M
authors.initials: RM
authors.lastname: Lyon
authors.forename: J
authors.initials: J
authors.lastname: Klein
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004185:Disability Evaluation; D016002:Discriminant Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D012600:Scoliosis / Q000145:classification* / Q000503:physiopathology*; D013131:Spine / Q000503:physiopathology