title: Proximal humeral fracture classification systems revisited.
abstract: OBJECTIVE
  This study evaluated several classification systems and expert surgeons' anatomic understanding of these complex injuries based on a consecutive series of patients. We hypothesized that current proximal humeral fracture classification systems, regardless of imaging methods, are not sufficiently reliable to aid clinical management of these injuries.
  
  
  METHODS
  Complex fractures in 96 consecutive patients were investigated by generation of rapid sequence prototyping models from computed tomography Digital Imaging and Communications in Medicine (DICOM) imaging data. Four independent senior observers were asked to classify each model using 4 classification systems: Neer, AO, Codman-Hertel, and a prototype classification system by Resch. Interobserver and intraobserver κ coefficient values were calculated for the overall classification system and for selected classification items.
  
  
  RESULTS
  The κ coefficient values for the interobserver reliability were 0.33 for Neer, 0.11 for AO, 0.44 for Codman-Hertel, and 0.15 for Resch. Interobserver reliability κ coefficient values were 0.32 for the number of fragments and 0.30 for the anatomic segment involved using the Neer system, 0.30 for the AO type (A, B, C), and 0.53, 0.48, and 0.08 for the Resch impaction/distraction, varus/valgus and flexion/extension subgroups, respectively. Three-part fractures showed low reliability for the Neer and AO systems.
  
  
  CONCLUSIONS
  Currently available evidence suggests fracture classifications in use have poor intra- and inter-observer reliability despite the modality of imaging used thus making treating these injuries difficult as weak as affecting scientific research as well. This study was undertaken to evaluate the reliability of several systems using rapid sequence prototype models.
  
  
  CONCLUSIONS
  Overall interobserver κ values represented slight to moderate agreement. The most reliable interobserver scores were found with the Codman-Hertel classification, followed by elements of Resch's trial system. The AO system had the lowest values. The higher interobserver reliability values for the Codman-Hertel system showed that is the only comprehensive fracture description studied, whereas the novel classification by Resch showed clear definition in respect to varus/valgus and impaction/distraction angulation.
authors.affiliation: Division of Surgery Oncology Reproductive Medicine and Anaesthetics, Imperial College London, UK. a.majed@imperial.ac.uk
authors.forename: Addie
authors.initials: A
authors.lastname: Majed
authors.forename: Iain
authors.initials: I
authors.lastname: Macleod
authors.forename: Anthony M J
authors.initials: AM
authors.lastname: Bull
authors.forename: Karol
authors.initials: K
authors.lastname: Zyto
authors.forename: Herbert
authors.initials: H
authors.lastname: Resch
authors.forename: Ralph
authors.initials: R
authors.lastname: Hertel
authors.forename: Peter
authors.initials: P
authors.lastname: Reilly
authors.forename: Roger J H
authors.initials: RJ
authors.lastname: Emery
mesh_terms: D006801:Humans; D007091:Image Processing, Computer-Assisted; D015588:Observer Variation; D015203:Reproducibility of Results; D012784:Shoulder Fractures / Q000145:classification* / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed