title: Ulnar variance as a predictor of persistent instability following Galeazzi fracture-dislocations.
abstract: BACKGROUND
  We investigated the radiographic parameters that may predict distal radial ulnar joint (DRUJ) instability in surgically treated radial shaft fractures. In our clinical experience, there are no previously reported radiographic parameters that are universally predictive of DRUJ instability following radial shaft fracture.
  
  
  METHODS
  Fifty consecutive patients, ages 20-79 years, with unilateral radial shaft fractures and possible associated DRUJ injury were retrospectively identified over a 5-year period. Distance from radial carpal joint (RCJ) to fracture proportional to radial shaft length, ulnar variance, and ulnar styloid fractures were correlated with DRUJ instability after surgical treatment.
  
  
  RESULTS
  Twenty patients had persistent DRUJ incongruence/instability following fracture fixation. As a proportion of radial length, the distance from the RCJ to the fracture line did not significantly differ between those with persistent DRUJ instability and those without (p = 0.34). The average initial ulnar variance was 5.5 mm (range 2-12 mm, SD = 3.2) in patients with DRUJ instability and 3.8 mm (range 0-11 mm, SD = 3.5) in patients without. Only 4/20 patients (20%) with DRUJ instability had normal ulnar variance (-2 to +2 mm) versus 15/30 (50%) patients without (p = 0.041).
  
  
  CONCLUSIONS
  In the setting of a radial shaft fracture, ulnar variance greater or less than 2 mm was associated with a greater likelihood of DRUJ incongruence/instability following fracture fixation.
authors.affiliation: NYU Hospital for Joint Diseases, 301 East 17th Street Suite 1402, New York, NY, 10003, USA.
authors.forename: Richelle
authors.initials: R
authors.lastname: Takemoto
authors.forename: Michelle
authors.initials: M
authors.lastname: Sugi
authors.forename: Igor
authors.initials: I
authors.lastname: Immerman
authors.forename: Nirmal
authors.initials: N
authors.lastname: Tejwani
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Egol
mesh_terms: D000328:Adult; D000368:Aged; D018483:Diaphyses / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery; D005260:Female; D005592:Fracture Fixation / Q000009:adverse effects*; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000209:etiology*; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011859:Radiography; D011884:Radius / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery; D012189:Retrospective Studies; D014457:Ulna / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery; D014458:Ulna Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D014955:Wrist Joint / Q000000981:diagnostic imaging*; D055815:Young Adult