title: Inter and intra-observer agreement evaluation of the AO and the Tronzo classification systems of fractures of the trochanteric area.
abstract: BACKGROUND
  We performed an agreement study of the AO and the Tronzo classifications of fractures of the trochanteric area to determine if they allow communication among practitioners with different levels of expertise.
  
  
  METHODS
  Complete radiographs of 70 patients with trochanteric fractures were classified by nine evaluators (three hip sub-specialists, three orthopaedic surgery residents and three medical interns) using the AO and the Tronzo classifications. After a six-week interval, all cases were presented in a random sequence for repeat evaluation. The Kappa coefficient (k) was used to determine inter- and intra-observer agreement.
  
  
  RESULTS
  Inter-observer: considering the main AO fracture types, the agreement was moderate for sub-specialists (k = 0.60 [0.50-0.70]), residents (k = 0.58 [0.48-0.69]) and medical interns (k = 0.56 [0.45-0.69]). Using AO sub-types, all groups achieved fair agreement (sub-specialists: k = 0.31 [0.25-0.38]; residents: k = 0.32 [0.26-0.38]; medical interns: k = 0.30 [0.24-0.36]). For the Tronzo classification, sub-specialists (k = 0.56 [0.48-0.65]) and residents (k = 0.47 [0.39-0.55]) obtained moderate agreement; medical interns reached fair agreement (k = 0.33 [0.25-0.41]). Intra-observer: considering the main AO fracture types, sub-specialists (k = 0.79 [0.69-0.89]), residents (k = 0.71 [0.60-0.81]) and medical interns (k = 0.70 [0.59-0.82]) obtained substantial agreement. Considering AO sub-types, sub-specialists (k = 0.50 [0.45-0.56]) and medical interns (k = 0.54 [0.48-0.69]) achieved moderate agreement; residents (k = 0.39 [0.33-0.45]) achieved fair agreement. Using the Tronzo classification, all groups obtained substantial agreement (sub-specialists: k = 0.66 [0.58-0.74]; residents: k = 0.63 [0.55-0.71]; medical interns: k = 0.68 [0.60-0.76]).
  
  
  CONCLUSIONS
  The AO classification allows an adequate communication when considering the main fracture types; the agreement within sub-types is not satisfactory. The Tronzo classification does not allow reliable communication between medical professionals.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Pontificia Universidad Catolica de Chile, Marcoleta 352, Santiago, Chile. Electronic address: jurrutia@med.puc.cl.
authors.forename: Julio
authors.initials: J
authors.lastname: Urrutia
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Pontificia Universidad Catolica de Chile, Marcoleta 352, Santiago, Chile.
authors.forename: Tomas
authors.initials: T
authors.lastname: Zamora
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Pontificia Universidad Catolica de Chile, Marcoleta 352, Santiago, Chile.
authors.forename: Pablo
authors.initials: P
authors.lastname: Besa
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Pontificia Universidad Catolica de Chile, Marcoleta 352, Santiago, Chile.
authors.forename: Maximiliano
authors.initials: M
authors.lastname: Zamora
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Pontificia Universidad Catolica de Chile, Marcoleta 352, Santiago, Chile.
authors.forename: Daniel
authors.initials: D
authors.lastname: Schweitzer
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Pontificia Universidad Catolica de Chile, Marcoleta 352, Santiago, Chile.
authors.forename: Ianiv
authors.initials: I
authors.lastname: Klaber
mesh_terms: D005269:Femur / Q000000981:diagnostic imaging*; D006620:Hip Fractures / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D021621:Imaging, Three-Dimensional; D015588:Observer Variation; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D015599:Trauma Severity Indices
keywords: Agreement study; Trochanteric area fracture classification; Trochanteric fractures of the proximal femur