title: Acute knee trauma: analysis of multidetector computed tomography findings and comparison with conventional radiography.
abstract: OBJECTIVE
  To evaluate the multidetector computed tomography (MDCT) findings of acute knee trauma and to compare radiography with MDCT in patients referred to a level 1 trauma center.
  
  
  METHODS
  During a 5-year period, a total of 415 MDCT examinations were performed on 409 patients with acute knee trauma to reveal complex fracture anatomy or rule out a fracture. MDCT and primary radiographs were re-evaluated with respect to fracture location and trauma mechanism. Tibial plateau fractures were further analyzed depending on anatomical location: anterior-medial, anterior-lateral, posterior-lateral, and posterior-medial regions. Maximal depression of the tibial articular surface was measured. Findings on the primary knee radiographs were compared with MDCT findings.
  
  
  RESULTS
  Of the 409 patients, 356 (87%) had a knee fracture. A total of 451 fractures were found in all anatomic regions: distal femur (n=49), proximal tibia (n=307), patella (n=23), and proximal fibula (n=72). Primary radiographs were available in 316 (76%) cases. Of these, 225 (71%) had MDCT in order to reveal the fracture anatomy better, and 91 (29%) had a subsequent MDCT after negative plain radiographs. Overall sensitivity of radiography was 83%, while negative predictive value was 49%. On radiography, tibial plateau articular depression was underestimated in all regions except when the fracture consisted of the whole half of the anterior or posterior plateau. The three main injury mechanisms were traffic accident, a simple fall, and sport. In 49 cases (15%), primary radiographs were suboptimal due to positioning.
  
  
  CONCLUSIONS
  In severely injured patients, diagnostically sufficient radiographs are difficult to obtain, and therefore a negative radiograph is not reliable in ruling out a fracture. In these patients, MDCT is a fast and accurate examination and is also recommended in patients with tibial plateau fractures or complex knee injuries in order to evaluate the fracture adequately.
authors.affiliation: Helsinki Medical Imaging Center, Department of Radiology, Helsinki University Central Hospital, Toolo Trauma Center, Helsinki, Finland. antti.mustonen@hus.fi
authors.forename: A O T
authors.initials: AO
authors.lastname: Mustonen
authors.forename: S K
authors.initials: SK
authors.lastname: Koskinen
authors.forename: M J
authors.initials: MJ
authors.lastname: Kiuru
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging; D005360:Fibula / Q000000981:diagnostic imaging / Q000293:injuries; D050723:Fractures, Bone / Q000000981:diagnostic imaging; D006801:Humans; D007718:Knee Injuries / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010329:Patella / Q000000981:diagnostic imaging / Q000293:injuries; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013978:Tibial Fractures / Q000000981:diagnostic imaging; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed