title: Incidence and fracture morphology of posterolateral fragments in lateral and bicondylar tibial plateau fractures.
abstract: OBJECTIVE
  This study aimed to evaluate the incidence and morphologic features of posterolateral fragments in lateral and bicondylar tibial plateau fractures.
  
  
  METHODS
  This study used retrospective chart and computed tomography (CT) reviews.
  
  
  METHODS
  The study was conducted in a university hospital.
  
  
  METHODS
  All patients in whom lateral and bicondylar tibial plateau fractures had been diagnosed from May 2005 to December 2011 were reviewed.
  
  
  METHODS
  Two hundred seventy-eight OTA type B and type C tibial plateau fractures were identified using a retrospective chart review. Of the 197 patients who underwent CTs before surgery, 7 CTs were excluded because they had no sagittal or axial view, and the remaining 190 cases were enrolled to determine the incidence and morphologic characteristics of posterolateral fragments. The parameters for the morphologic evaluation included the lateral major articular fracture angle, posterior major articular fracture angle, diagonal distance, lateral anteroposterior distance (LAPD), posterior horizontal distances, posterior cortical height, sagittal fracture angle, and articular surface area. The displacement of posterolateral fragment was measured on axial image and classified as none, minor, or major by a gap of 5 mm.
  
  
  RESULTS
  The incidence of posterolateral fragments included 84 cases (44.2%). Based on the OTA fracture classification system, 37 type B (35.9%) and 47 type C (54%) posterolateral fragments were identified. The mean lateral major articular fracture angle was 12.69 degrees (range, -56.02 to 72.44 degrees), and the mean posterior major articular fracture angle was 19.13 degrees (range, -39.47 to 61.10 degrees). The average diagonal distance was 32.75 mm (range, 15.03-59.14 mm). The LAPD averaged 10.22 mm (range, -11.18 to 31.17 mm), and the mean posterior horizontal distance was 22.93 mm (range, 4.1 to 49.95 mm). The average posterior cortical height was 31.12 mm (range, 10.84-63.93 mm), and the average sagittal fracture angle was 78.48 degrees (range, 41.69-105.12 degrees). The mean articular surface area was 522.18 mm2 (14.5%) of the total tibial articular surface.
  
  
  CONCLUSIONS
  Posterolateral fragments are not uncommon in lateral and bicondylar tibial plateaus. This fragment has an inverted conical shape that is in a vertically oriented pattern and occupied nearly one-third of the surface area of the lateral tibial plateau. The preoperative CT measurement, especially for the LAPD, can be used for determining the best fixation strategy for the posterolateral fragment.
  
  
  METHODS
  Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
authors: *Orthopaedic Surgery, National Medical Center, Seoul, Korea; †Orthopaedic Trauma Division, Trauma Center, Gachon University Gil Hospital, Incheon, Korea; and ‡Department of Orthopaedic Surgery, Kyungpook National University Hospital, Daegu, Korea.
authors: Hoon-Sang
authors: HS
authors: Sohn
authors: Yong-Cheol
authors: YC
authors: Yoon
authors: Jae-Woo
authors: JW
authors: Cho
authors: Won-Tae
authors: WT
authors: Cho
authors: Chang-Wug
authors: CW
authors: Oh
authors: Jong-Keon
authors: JK
authors: Oh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013978:Tibial Fractures / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000601:surgery; D014057:Tomography, X-Ray Computed