title: Anatomy and classification of the posterior tibial fragment in ankle fractures.
abstract: BACKGROUND
  The aim of this study was to analyze the pathoanatomy of the posterior fragment on the basis of a comprehensive CT examination, including 3D reconstructions, in a large patient cohort.
  
  
  METHODS
  One hundred and forty one consecutive individuals with an ankle fracture or fracture-dislocation of types Weber B or Weber C and evidence of a posterior tibial fragment in standard radiographs were included in the study. The mean patient age was 49 years (range 19-83 years). The exclusion criteria were patients below 18 years of age, inability to provide written consent, fractures of the tibial pilon, posttraumatic arthritis and pre-existing deformities. In all patients, post-injury radiographs were obtained in anteroposterior, mortise and lateral views. All patients underwent CT scanning in transverse, sagittal and frontal planes. 3D CT reconstruction was performed in 91 patients.
  
  
  RESULTS
  We were able to classify 137 cases into one of the following four types with constant pathoanatomic features: type 1: extraincisural fragment with an intact fibular notch, type 2: posterolateral fragment extending into the fibular notch, type 3: posteromedial two-part fragment involving the medial malleolus, type 4: large posterolateral triangular fragment. In the 4 cases it was not possible to classify the type of the posterior tibial fragment. These were collectively termed type 5 (irregular, osteoporotic fragments).
  
  
  CONCLUSIONS
  It is impossible to assess the shape and size of the posterior malleolar fragment, involvement of the fibular notch, or the medial malleolus, on the basis of plain radiographs. The system that we propose for classification of fractures of the posterior malleolus is based on CT examination and takes into account the size, shape and location of the fragment, stability of the tibio-talar joint and the integrity of the fibular notch. It may be a useful indication for surgery and defining the most useful approach to these injuries.
authors.affiliation: Department of Orthopaedic Trauma, First Faculty of Medicine, Central Military Hospital, Charles University, U Vojenské nemocnice 1200, 169 02, Prague 6, Czech Republic, bartonicek.jan@seznam.cz.
authors.forename: Jan
authors.initials: J
authors.lastname: Bartoníček
authors.forename: Stefan
authors.initials: S
authors.lastname: Rammelt
authors.forename: Karel
authors.initials: K
authors.lastname: Kostlivý
authors.forename: Václav
authors.initials: V
authors.lastname: Vaněček
authors.forename: Daniel
authors.initials: D
authors.lastname: Klika
authors.forename: Ivo
authors.initials: I
authors.lastname: Trešl
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D064386:Ankle Fractures / Q000145:classification* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D013639:Tarsal Bones / Q000033:anatomy & histology*; D013977:Tibia / Q000033:anatomy & histology*; D013978:Tibial Fractures / Q000145:classification* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult