title: Preoperative classification assessment reliability and influence on the length of intertrochanteric fracture operations.
abstract: OBJECTIVE
  The accuracy of intertrochanteric fracture classification is important; indeed, the patient outcomes are dependent on their classification. The aim of this study was to use the AO classification system to evaluate the variation in classification between X-ray and computed tomography (CT)/3D CT images. Then, differences in the length of surgery were evaluated based on two examinations.
  
  
  METHODS
  Intertrochanteric fractures were reviewed and surgeons were interviewed. The rates of correct discrimination and misclassification (overestimates and underestimates) probabilities were determined. The impact of misclassification on length of surgery was also evaluated.
  
  
  RESULTS
  In total, 370 patents and four surgeons were included in the study. All patients had X-ray images and 210 patients had CT/3D CT images. Of them, 214 and 156 patients were treated by intramedullary and extramedullary fixation systems, respectively. The mean length of surgery was 62.1 ± 17.7 min. The overall rate of correct discrimination was 83.8 % and in the classification of A1, A2 and A3 were 80.0, 85.7 and 82.4 %, respectively. The rate of misclassification showed no significant difference between stable and unstable fractures (21.3 vs 13.1 %, P = 0.173). The overall rates of overestimates and underestimates were significantly different (5 vs 11.25 %, P = 0.041). Subtracting the rate of overestimates from underestimates had a positive correlation with prolonged surgery and showed a significant difference with intramedullary fixation (P < 0.001).
  
  
  CONCLUSIONS
  Classification based on the AO system was good in terms of consistency. CT/3D CT examination was more reliable and more helpful for preoperative assessment, especially for performance of an intramedullary fixation.
authors.affiliation: Orthopedic Department, The First Affiliated Hospital of Harbin Medical University, Harbin Medical University, Harbin, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Shen
authors.forename: FangKe
authors.initials: F
authors.lastname: Hu
authors.forename: LiHai
authors.initials: L
authors.lastname: Zhang
authors.forename: PeiFu
authors.initials: P
authors.lastname: Tang
authors.forename: ZhengGang
authors.initials: Z
authors.lastname: Bi
mesh_terms: D016267:External Fixators; D005594:Fracture Fixation, Intramedullary / Q000379:methods*; D006620:Hip Fractures / Q000145:classification* / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D061646:Operative Time; D011300:Preoperative Care; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome