title: Two and three-dimensional computed tomography for the classification and management of distal humeral fractures. Evaluation of reliability and diagnostic accuracy.
abstract: BACKGROUND
  Complex fractures of the distal part of the humerus can be difficult to characterize on plain radiographs and two-dimensional computed tomography scans. We tested the hypothesis that three-dimensional reconstructions of computed tomography scans improve the reliability and accuracy of fracture characterization, classification, and treatment decisions.
  
  
  METHODS
  Five independent observers evaluated thirty consecutive intra-articular fractures of the distal part of the humerus for the presence of five fracture characteristics: a fracture line in the coronal plane; articular comminution; metaphyseal comminution; the presence of separate, entirely articular fragments; and impaction of the articular surface. Fractures were also classified according to the AO/ASIF Comprehensive Classification of Fractures and the classification system of Mehne and Matta. Two rounds of evaluation were performed and then compared. Initially, a combination of plain radiographs and two-dimensional computed tomography scans (2D) were evaluated, and then, two weeks later, a combination of radiographs, two-dimensional computed tomography scans, and three-dimensional reconstructions of computed tomography scans (3D) were assessed.
  
  
  RESULTS
  Three-dimensional computed tomography improved both the intraobserver and the interobserver reliability of the AO classification system and the Mehne and Matta classification system. Three-dimensional computed tomography reconstructions also improved the intraobserver agreement for all fracture characteristics, from moderate (average kappa [kappa2D] = 0.554) to substantial agreement (kappa3D = 0.793). The addition of three-dimensional images had limited influence on the interobserver reliability and diagnostic characteristics (sensitivity, specificity, and accuracy) for the recognition of specific fracture characteristics. Three-dimensional computed tomography images improved intraobserver agreement (kappa2D = 0.62 compared with kappa3D = 0.75) but not interobserver agreement (kappa2D = 0.24 compared with kappa3D = 0.28) for treatment decisions.
  
  
  CONCLUSIONS
  Three-dimensional reconstructions improve the reliability, but not the accuracy, of fracture classification and characterization. The influence of three-dimensional computed tomography was much more notable for intraobserver comparisons than for interobserver comparisons, suggesting that different observers see different things in the scans-most likely a reflection of the training, knowledge, and experience of the observer with regard to these relatively uncommon and complex injuries.
authors.affiliation: Massachusetts General Hospital, Yawkey Center, Suite 2100, 55 Fruit Street, Boston, MA 02116, U SA.
authors.forename: Job
authors.initials: J
authors.lastname: Doornberg
authors.forename: Anneluuk
authors.initials: A
authors.lastname: Lindenhovius
authors.forename: Peter
authors.initials: P
authors.lastname: Kloen
authors.forename: C Niek
authors.initials: CN
authors.lastname: van Dijk
authors.forename: David
authors.initials: D
authors.lastname: Zurakowski
authors.forename: David
authors.initials: D
authors.lastname: Ring
mesh_terms: D000328:Adult; D006801:Humans; D006810:Humeral Fractures / Q000145:classification* / Q000000981:diagnostic imaging*; D021621:Imaging, Three-Dimensional; D015588:Observer Variation; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000706:statistics & numerical data