title: 3D Model Analysis of Ankle Flexion on Anatomic Reduction of a Syndesmotic Injury.
abstract: BACKGROUND
  The effect of ankle positioning during suture-button fixation for syndesmosis repair on range of motion (ROM) and anatomic reduction has yet to be investigated. The purpose of this cadaveric study was to compare the effects of 3 different ankle positions during suture-button repair on volumetric reduction of the syndesmosis, fibular displacement, and ROM of the ankle using 3-dimensional computed tomography (CT) analysis. The null hypothesis was that ankle position during fixation would not affect syndesmotic volume restoration, fibular displacement, or ROM.
  
  
  METHODS
  Twelve matched pair (n = 24) human cadaveric specimens were used for this study. Prior to syndesmotic sectioning, ROM assessment and CT scans were performed. Following sectioning of the syndesmosis, specimens were repaired in plantarflexion, dorsiflexion, or neutral, and simulated postrepair ROM evaluations and CT scans were repeated. Least squares mean differences between repair groups and the preinjury state were compared by analysis of variance and Tukey's method.
  
  
  RESULTS
  There were no significant differences between repair groups for volumetric reduction ( P = .917), fibular displacement (anterior-posterior, P = .805; medial-lateral, P = .949), or dorsiflexion capacity ( P = .249). Among all specimens, compared with the preinjury state, there was a significant mean ± SD volume reduction of 337 ± 400 mm3and medial displacement of 1.9 ± 1.5 mm.
  
  
  CONCLUSIONS
  This study failed to reject the null hypothesis and demonstrated that ankle flexion at the time of syndesmotic fixation with a suture-button construct had no significant in vitro effect on volume changes, fibular displacement, or dorsiflexion capacity. However, in comparison to the preinjured state, suture-button repair resulted in significant overcompression with respect to syndesmosis volume and medial displacement of the fibula.
  
  
  CONCLUSIONS
  Ankle position at the time of syndesmotic fixation did not affect overall ankle ROM when using a suture-button construct; however, overcompression was observed in all positions. The clinical impact of syndesmotic overcompression remains largely unknown.
authors.affiliation: 1 Steadman Philippon Research Institute, Vail, CO, USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Schon
authors.affiliation: 1 Steadman Philippon Research Institute, Vail, CO, USA.
authors.forename: Jacob D
authors.initials: JD
authors.lastname: Mikula
authors.affiliation: 1 Steadman Philippon Research Institute, Vail, CO, USA.|2 The Steadman Clinic, Vail, CO, USA.
authors.forename: Jonathon D
authors.initials: JD
authors.lastname: Backus
authors.affiliation: 1 Steadman Philippon Research Institute, Vail, CO, USA.
authors.forename: Melanie B
authors.initials: MB
authors.lastname: Venderley
authors.affiliation: 1 Steadman Philippon Research Institute, Vail, CO, USA.
authors.forename: Grant J
authors.initials: GJ
authors.lastname: Dornan
authors.affiliation: 1 Steadman Philippon Research Institute, Vail, CO, USA.|2 The Steadman Clinic, Vail, CO, USA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: LaPrade
authors.affiliation: 1 Steadman Philippon Research Institute, Vail, CO, USA.|2 The Steadman Clinic, Vail, CO, USA.
authors.forename: Thomas O
authors.initials: TO
authors.lastname: Clanton
mesh_terms: D016512:Ankle Injuries / Q000503:physiopathology / Q000601:surgery*; D000843:Ankle Joint / Q000503:physiopathology / Q000601:surgery*; D005360:Fibula / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D016059:Range of Motion, Articular / Q000502:physiology*; D013536:Suture Techniques; D014057:Tomography, X-Ray Computed
keywords: Computed tomography; TightRope; suture-button; syndesmosis; tibiofibular