title: Reliability and Reproducibility of the OTA/AO Classification for Humeral Shaft Fractures.
abstract: OBJECTIVE
  This study aimed to determine interobserver reliability and intraobserver reproducibility of the OTA/AO classification for humeral shaft fractures, and to evaluate differences between fracture types, fracture groups, and surgical specializations.
  
  
  METHODS
  Thirty observers (25 orthopaedic trauma surgeons and 5 general orthopaedic surgeons) independently classified 90 humeral shaft fractures according to the OTA/AO classification. Patients of 16 years and older were included. Periprosthetic, recurrent, and pathological fractures were excluded. Radiographs were provided in random order, and observers were blinded to clinical information. To determine intraobserver agreement, radiographs were reviewed again after 2 months in a different random order. Agreement was assessed using kappa statistics.
  
  
  RESULTS
  Interobserver agreement for the 3 fracture types was moderate (κ = 0.60; 0.59-0.61). It was substantial for type A (κ = 0.77; 0.70-0.84) and moderate for type B (κ = 0.52; 0.46-0.58) and type C fractures (κ = 0.46; 0.42-0.50). Interobserver agreement for the 9 fracture groups was moderate (κ = 0.48; 95% CI, 0.48-0.48). Orthopaedic trauma surgeons had better overall agreement for fracture types, and general orthopaedic surgeons had better overall agreement for fracture groups. Observers classified 64% of fractures identically in both rounds. Intraobserver agreement was substantial for the 3 types (κ = 0.80; 0.77-0.81) and 9 groups (κ = 0.80; 0.77-0.82). Intraobserver agreement showed no differences between surgical disciplines.
  
  
  CONCLUSIONS
  The OTA/AO classification for humeral shaft fractures has a moderate interobserver and substantial intraobserver agreement for fracture types and groups.
authors.affiliation: *Trauma Research Unit, Department of Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands; †Department of Surgery, Maasstad Hospital, Rotterdam, the Netherlands; and ‡Department of Surgery, Albert Schweitzer Hospital, Dordrecht, the Netherlands.
authors.forename: Kiran C
authors.initials: KC
authors.lastname: Mahabier
authors.forename: Esther M M
authors.initials: EM
authors.lastname: Van Lieshout
authors.forename: Boyd C
authors.initials: BC
authors.lastname: Van Der Schaaf
authors.forename: Gert R
authors.initials: GR
authors.lastname: Roukema
authors.forename: Bas J
authors.initials: BJ
authors.lastname: Punt
authors.forename: Michael H J
authors.initials: MH
authors.lastname: Verhofstad
authors.forename: Dennis
authors.initials: D
authors.lastname: Den Hartog
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D006810:Humeral Fractures / Q000145:classification* / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D015588:Observer Variation; D009985:Orthopedics / Q000379:methods / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015599:Trauma Severity Indices; D014194:Traumatology / Q000379:methods / Q000592:standards*; D055815:Young Adult