title: Arthroscopic Evaluation of Syndesmotic Instability in a Cadaveric Model.
abstract: BACKGROUND
  Ankle fractures are among the most common lower extremity injuries. Proper care requires evaluation for syndesmotic ligament disruption. Ankle arthroscopy has been proposed as an intraoperative tool that can evaluate stability. Our focus was to evaluate the amount of displacement produced in the coronal, sagittal, and transverse planes visualized through ankle arthroscopy in a cadaveric model.
  
  
  METHODS
  Seven below-knee specimens were mounted in a traction tower. Four groups were evaluated: no ligamentous disruption; anterior inferior tibiofibular ligament and interosseous ligament disruption; above plus anterior talofibular ligament and calcaneofibular ligament disruption; and posterior inferior tibiofibular ligament and transverse ligament disruption. Force was applied and measured using a digital scale. The amount of displacement of the fibula in relation to the center of the incisura was measured under arthroscopic evaluation using a calibrated probe.
  
  
  RESULTS
  An intact syndesmosis and lateral ankle ligaments provided multiplanar stability. In group 2, syndesmosis diastasis was appreciated in the transverse-external rotation plane with as little as 6 lb of force. In group 3, a greater amount of displacement was appreciated with less force. Multiplane instability was visible in every specimen with as little as 2 lb of force. Group 4 specimens were completely disrupted and so grossly unstable that testing was impossible.
  
  
  CONCLUSIONS
  Ankle arthroscopy has the potential to evaluate even partial disruption of the syndesmotic ligament complex. Instability in the sagittal and transverse planes was encountered early in the spectrum of disruption. Traditional evaluation methods have poor sensitivity for instability in these planes.
  
  
  CONCLUSIONS
  Arthroscopic evaluation of subtle displacement in multiple planes may assist the surgeon in understanding the extent of the syndesmotic injury. Further studies are necessary to determine to what extent instability requires fixation as well as the role for arthroscopy in assessing anatomic reduction of the syndesmosis after fixation is performed.
authors.affiliation: OhioHealth Doctors Hospital, Columbus, OH, USA.
authors.forename: B Collier
authors.initials: BC
authors.lastname: Watson
authors.affiliation: Orthopedic Foot and Ankle Department, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Lucas
authors.affiliation: Front Range Orthopaedics, Colorado Springs, CO, USA.
authors.forename: G Alex
authors.initials: GA
authors.lastname: Simpson
authors.affiliation: Orthopedic Foot and Ankle Center, Westerville, OH, USA ofacresearch@orthofootankle.com.
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Berlet
authors.affiliation: Orthopedic Foot and Ankle Center, Westerville, OH, USA.
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Hyer
mesh_terms: D016512:Ankle Injuries / Q000503:physiopathology* / Q000601:surgery; D001182:Arthroscopy; D002102:Cadaver; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology* / Q000601:surgery; D008023:Ligaments, Articular / Q000293:injuries*; D013314:Stress, Mechanical
keywords: arthroscopy; instability; syndesmosis; tibiofibular