title: Intraoperative diagnosis of syndesmosis injuries in external rotation ankle fractures.
abstract: OBJECTIVE
  This study was designed to compare intraoperative fluoroscopic stress testing, static radiographs, and biomechanical criteria for the diagnosis of distal tibiofibular syndesmotic instability associated with external rotation type ankle fractures.
  
  
  METHODS
  Prospective, consecutive series.
  
  
  METHODS
  Academic level 1 trauma center.
  
  
  METHODS
  Thirty-eight skeletally mature patients with unstable unilateral external rotation ankle fractures were prospectively recruited.
  
  
  METHODS
  Before surgery, the treating surgeon detailed the operative treatment plan, including need for syndesmotic fixation. In pronation-external rotation injuries, biomechanical criteria were applied to predict syndesmotic instability. Ankles were examined using intraoperative fluoroscopic external rotation stress tests. The contralateral uninjured limb was used as a control. A 7.2-Nm force was applied for the external rotation stress examination. Stress testing was performed after lateral malleolar fixation and repeated after medial and syndesmotic fixation.
  
  
  METHODS
  The incidence of syndesmotic instability was determined based on radiographic clear space measurements and compared with previously published criteria.
  
  
  RESULTS
  Intraoperative fluoroscopy detected unpredicted syndesmotic instability in 37% of ankles. In supination-external rotation (OTA 44B) injuries, unpredicted syndesmosis instability was found in 10 of 30 patients (33%). In pronation-external rotation injuries (OTA 44C), 4 of 7 patients (57%) were associated with syndesmosis disruption not predicted by biomechanical criteria. In bimalleolar fractures, syndesmosis fixation improved stability compared with rigid bimalleolar fixation alone (P < 0.01).
  
  
  CONCLUSIONS
  Preoperative radiographs and biomechanical criteria are unable to routinely predict the presence or absence of syndesmosis instability. Rigid bimalleolar fixation was frequently not sufficient to stabilize syndesmotic disruption. Intraoperative stress fluoroscopy is a valuable tool for detection of unstable syndesmotic injuries.
authors.affiliation: London Health Sciences Center, University of Western Ontario, Division of Orthopaedic Surgery, London, Ontario, Canada N6A 4G5.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Jenkinson
authors.forename: David W
authors.initials: DW
authors.lastname: Sanders
authors.forename: Mark D
authors.initials: MD
authors.lastname: Macleod
authors.forename: Andrea
authors.initials: A
authors.lastname: Domonkos
authors.forename: Jeanette
authors.initials: J
authors.lastname: Lydestadt
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016512:Ankle Injuries / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D050723:Fractures, Bone / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D008023:Ligaments, Articular / Q000293:injuries* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010808:Physical Examination / Q000379:methods; D011379:Prognosis; D011859:Radiography; D015203:Reproducibility of Results; D012399:Rotation; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods