title: Agreement of olecranon fractures before and after the exposure to four classification systems.
abstract: BACKGROUND
  Although classification systems of olecranon fractures are important to help choose the best treatment and to predict prognosis, their degree of observer agreement is poorly investigated. The objective of this study was to investigate the intraobserver and interobserver reliability of currently used classification systems for olecranon fractures. Our hypothesis is that the Colton classification presents an acceptable agreement because it is simpler to use; on the other hand, considering the AO classification's complexity, we expect it to reach a lower level of agreement.
  
  
  METHODS
  Radiographic images of elbow joint fractures were classified according to Colton, AO, Mayo, and Schatzker classification systems. The raters were 8 orthopedic surgeons split into 2 groups with 4 participants each, one with specialists in upper extremity surgery and the other with orthopedic surgeons without a specific focus on upper extremity surgery. This first procedure was the pretest training, aimed at calibrating participants' judgment. Image classification was conducted after all training was completed. After 30 days from the initial rating session, the test was conducted once again following the exact same procedures.
  
  
  RESULTS
  The Colton classification has substantial intraobserver and interobserver agreement for specialists and nonspecialists. The Schatzker classification revealed a fair agreement for both specialists and nonspecialists. A fair concordance was also found for the Mayo classification. The AO classification demonstrated a moderate rate of agreement for specialists, whereas nonspecialists presented slight intraobserver agreement.
  
  
  CONCLUSIONS
  No classification system is widely accepted because it can be affected by interobserver variability, which can raise questions about its use in a research as well as in a clinical context.
authors.affiliation: Orthopedics and Traumatology Institute (IOT), Joinville, SC, Brazil.
authors.forename: Cesar A
authors.initials: CA
authors.lastname: Benetton
authors.affiliation: Orthopedics and Traumatology Institute (IOT), Joinville, SC, Brazil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Cesa
authors.affiliation: Orthopedics and Traumatology Institute (IOT), Joinville, SC, Brazil.
authors.forename: Gabriel
authors.initials: G
authors.lastname: El-Kouba Junior
authors.affiliation: Orthopedics and Traumatology Institute (IOT), Joinville, SC, Brazil. Electronic address: apbonilauri@gmail.com.
authors.forename: Ana Paula B
authors.initials: AP
authors.lastname: Ferreira
authors.affiliation: Medicine Department, Faculdade Inga, Maringá, PR, Brazil.
authors.forename: João Ricardo N
authors.initials: JR
authors.lastname: Vissoci
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, NC, USA.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Pietrobon
mesh_terms: D002983:Clinical Competence; D006801:Humans; D057072:Intra-Articular Fractures / Q000145:classification* / Q000000981:diagnostic imaging; D015588:Observer Variation; D056740:Olecranon Process / Q000000981:diagnostic imaging / Q000293:injuries*; D011859:Radiography; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014458:Ulna Fractures / Q000145:classification* / Q000000981:diagnostic imaging
keywords: AO classification; Colton classification; Inter/intraobserver; Mayo classification; Schatzker classification; agreement; olecranon fracture