title: Diagnostic Accuracy of 2-Dimensional Computed Tomography for Articular Involvement and Fracture Pattern of Posterior Malleolar Fractures.
abstract: Up to 44% of ankle fractures have involvement of the posterior tibial margin. Fracture size and morphology are important factors to guide treatment of these fragments, but reliability of plain radiography in estimating size is low. The aim of the current study was to evaluate the accuracy of 2-dimensional computed tomography (2DCT) in the assessment of posterior malleolar fractures. Additionally, the diagnostic accuracy of 2DCT and its value in preoperative planning was evaluated.
  
  
  
  Thirty-one patients with 31 ankle fractures including a posterior malleolar fragment were selected. Preoperative CT scans were analyzed by 50 observers from 23 countries. Quantitative 3-dimensional CT (Q3DCT) reconstructions were used as a reference standard.
  
  
  
  Articular involvement of the posterior fragment was overestimated on 2DCT by factors 1.6, 1.4, and 2.2 for Haraguchi types I, II, and III, respectively. Interobserver agreement on operative management ("to fix, or not to fix?") was substantial (κ = 0.69) for Haraguchi type I fractures, fair (κ = 0.23) for type II fractures, and poor (κ = 0.09) for type III fractures. 2DCT images led to a change in treatment of the posterior malleolus in 23% of all fractures. Surgeons would operatively treat type I fractures in 63%, type II fractures in 67%, and type III fractures in 22%.
  
  
  
  Surgeons overestimated true articular involvement of posterior malleolar fractures on 2DCT scans. 2DCT showed some additional value in estimating the involved articular surface when compared to plain radiographs; however, this seemed not yet sufficient to accurately read the fractures. Analysis of the CT images showed a significant influence on choice of treatment in 23% with a shift toward operative treatment in 12% of cases compared to evaluating plain lateral radiographs alone.
  
  
  
  Level III, comparative study.
authors.affiliation: Department of Orthopaedic Surgery, Academic Medical Center, Amsterdam, the Netherlands dtmeijer@gmail.com.
authors.forename: Diederik T
authors.initials: DT
authors.lastname: Meijer
authors.affiliation: Trauma Unit, Department of Surgery, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Robert-Jan O
authors.initials: RJ
authors.lastname: de Muinck Keizer
authors.affiliation: University of Amsterdam Orthopaedic Residency Program (PGY5) and Postdoc Research Fellow, Orthotrauma Research Center Amsterdam, the Netherlands.
authors.forename: Job N
authors.initials: JN
authors.lastname: Doornberg
authors.affiliation: Department of Orthopaedic Surgery, Slotervaart Hospital, Amsterdam, the Netherlands.
authors.forename: Inger N
authors.initials: IN
authors.lastname: Sierevelt
authors.affiliation: University of Amsterdam Orthopaedic Residency Program (PGY5) and Postdoc Research Fellow, Orthotrauma Research Center Amsterdam, the Netherlands.
authors.forename: Sjoerd A
authors.initials: SA
authors.lastname: Stufkens
authors.affiliation: Department of Orthopaedic Surgery, Academic Medical Center, Amsterdam, Academic Center for Evidence based Sports medicine (ACES), Amsterdam Collaboration for Health and Safety in Sports (ACHSS), Amsterdam, the Netherlands.
authors.forename: Gino M M J
authors.initials: GM
authors.lastname: Kerkhoffs
authors.affiliation: Academic Medical Center, Amsterdam, Amsterdam, the Netherlands.
authors.forename: C Niek
authors.initials: CN
authors.lastname: van Dijk
mesh_terms: D064386:Ankle Fractures / Q000145:classification / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D015588:Observer Variation; D011300:Preoperative Care; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
keywords: Haraguchi classification; computed tomography; posterior malleolar fracture; quantitative 3-dimensional CT