title: Reliability of classification systems for intertrochanteric fractures of the proximal femur in experienced orthopaedic surgeons.
abstract: BACKGROUND
  The aim of this study was to determine the reliability of currently used classification systems for intertrochanteric fractures of the proximal femur, and to determine the reliability of these systems in experienced orthopaedic surgeons.
  
  
  METHODS
  Forty intertrochanteric fractures of the proximal femur were classified independently by five experienced observers using the AO, Evans, Kyle, and Boyd classification systems on two separate occasions 3 months apart. The interobserver and intraobserver variation was assessed using kappa statistics.
  
  
  RESULTS
  The level of agreement for classification into AO groups was almost perfect or substantial, and higher than other classification systems. When the fractures were further classified using the AO classification with subgroups, reliability became worse.
  
  
  CONCLUSIONS
  The current study suggests that the AO classification system with groups can be used more reliably to measure intertrochanteric fractures of the proximal femur than Evans, Kyle, and Boyd classification systems. However, the reliability of the AO classification with subgroups is not satisfactory.
authors.affiliation: Xinhua Hospital, Shanghai Second Medical University, Orthopaedic Surgery, 1665 Kongjiang Road, Shanghai 200092, China.
authors.forename: Wen-Jie
authors.initials: WJ
authors.lastname: Jin
authors.forename: Li-Yang
authors.initials: LY
authors.lastname: Dai
authors.forename: Yi-Min
authors.initials: YM
authors.lastname: Cui
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhou
authors.forename: Lei-Sheng
authors.initials: LS
authors.lastname: Jiang
authors.forename: Hua
authors.initials: H
authors.lastname: Lu
mesh_terms: D005270:Femur Head / Q000293:injuries*; D006620:Hip Fractures / Q000145:classification*; D006801:Humans; D015588:Observer Variation; D009985:Orthopedics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity