title: Can stress radiography of the knee help characterize posterolateral corner injury?
abstract: BACKGROUND
  Conventional MRI is limited for characterizing the posterolateral corner of the knee due to the region's anatomic variability and complexity; further, MRI is a static study and cannot demonstrate pathologic laxity. Stress radiography may provide additional information about instability.
  
  
  OBJECTIVE
  We therefore (1) correlated varus stress radiography with MRI findings, (2) compared opening in patients who underwent surgical posterolateral corner stabilization versus those who did not, and (3) determined whether stress radiography findings could supplement MRI for making treatment decisions.
  
  
  METHODS
  We retrospectively studied 26 patients (27 knee injuries) and correlated lateral compartment opening on varus stress radiography with severity of posterolateral corner injury on MRI. We compared radiographic findings in 18 patients with complete injuries who underwent posterolateral corner stabilization with five who did not.
  
  
  RESULTS
  A complete posterolateral corner injury on MRI was associated with an average of 18.6 mm (10.0-36.5 mm) of varus opening versus 12.8 mm (7.5-17.0 mm) in partial injuries. Opening in operative cases that underwent stabilization was 16.5 mm (11.0-36.5 mm) versus 11.0 mm (7.5-13.5 mm) for those that did not. Ten of 15 partial injuries underwent stabilization, for which the varus opening was 13.6 mm (11.0-17.0 mm). Average varus opening in partial injuries that did not undergo stabilization was 11.0 mm (7.5-13.5 mm).
  
  
  CONCLUSIONS
  Varus stress radiography correlated to MRI findings for posterolateral corner injury. The injuries we treated with reconstruction were associated with increased varus opening. In patients with partial posterolateral corner injury on MRI, we used degree of opening on varus stress radiography to aid the decision for stabilization.
  
  
  METHODS
  Level IV, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, PO Box 800159, Charlottesville, VA 22908, USA.
authors.forename: F Winston
authors.initials: FW
authors.lastname: Gwathmey
authors.forename: Marc A
authors.initials: MA
authors.lastname: Tompkins
authors.forename: Cree M
authors.initials: CM
authors.lastname: Gaskin
authors.forename: Mark D
authors.initials: MD
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007717:Knee / Q000000981:diagnostic imaging*; D007718:Knee Injuries / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D055815:Young Adult