title: Overtightening of the syndesmosis revisited and the effect of syndesmotic malreduction on ankle dorsiflexion.
abstract: BACKGROUND
  Ankle syndesmotic injuries are a significant source of morbidity and require anatomic reduction to optimize outcomes. Although a previous study concluded that maximal dorsiflexion during syndesmotic fixation was not required, methodologic weaknesses existed and several studies have demonstrated improved ankle dorsiflexion after removal of syndesmotic screws. The purposes of the current investigation are: (1) To assess the effect of compressive syndesmotic screw fixation on ankle dorsiflexion utilizing a controlled load and instrumentation allowing for precise measurement of motion. (2) To assess the effect of anterior & posterior syndesmotic malreduction after compressive syndesmotic screw fixation on ankle dorsiflexion.
  
  
  METHODS
  Fifteen lower limb cadaveric leg specimens were utilized for the study. Ankle dorsiflexion was measured utilizing a precise micro-sensor system after application of a consistent load in the (1) intact state, (2) after compression fixation with a syndesmotic screw and (3) after anterior & (4) posterior malreduction of the syndesmosis.
  
  
  RESULTS
  Following screw compression of the nondisplaced syndesmosis, dorsiflexion ROM was 99.7±0.87% (mean±standard error) of baseline ankle ROM. Anterior and posterior malreduction of the syndesmosis resulted in dorsiflexion ROM that was 99.1±1.75% and 98.6±1.56% of baseline ankle ROM, respectively. One-way ANOVA was performed showing no statistical significance between groups (p-value=0.88). Two-way ANOVA comparing the groups with respect to both the reduction condition (intact, anatomic reduction, anterior displacement, posterior displacement) and the displacement order (anterior first, posterior first) did not demonstrate a statistically significant effect (p-value=0.99).
  
  
  CONCLUSIONS
  Maximal dorsiflexion of the ankle is not required prior to syndesmotic fixation as no loss of motion was seen with compressive fixation in our cadaver model. Anterior or posterior syndesmotic malreduction following syndesmotic screw fixation had no effect on ankle dorsiflexion. Poor patient outcomes after syndesmotic malreduction may be due to other factors and not loss of dorsiflexion motion.
  
  
  METHODS
  IV.
authors.affiliation: Harvard Combined Orthopaedic Surgery Residency Program, Boston, MA, United States. Electronic address: tagonzalez@partners.org.
authors.forename: Tyler
authors.initials: T
authors.lastname: Gonzalez
authors.affiliation: Center for Advanced Orthopaedic Studies at Beth Israel Deaconess Medical Center - Harvard Medical School, Boston, MA, United States. Electronic address: jegan1@bidmc.harvard.edu.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Egan
authors.affiliation: Beth Israel Deaconess Medical Center, Boston, MA, United States. Electronic address: mghorban@bidmc.harvard.edu.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ghorbanhoseini
authors.affiliation: Harvard Combined Orthopaedic Surgery Residency Program, Boston, MA, United States. Electronic address: MBBLAIS@PARTNERS.ORG.
authors.forename: Micah
authors.initials: M
authors.lastname: Blais
authors.affiliation: Center for Advanced Orthopaedic Studies at Beth Israel Deaconess Medical Center - Harvard Medical School, Boston, MA, United States. Electronic address: alechtig@bidmc.harvard.edu.
authors.forename: Aron
authors.initials: A
authors.lastname: Lechtig
authors.affiliation: The Commonwealth Medical College, Scranton, PA, United States. Electronic address: Bvelasco@tcmc.edu.
authors.forename: Brian
authors.initials: B
authors.lastname: Velasco
authors.affiliation: Harvard Combined Orthopaedic Surgery Residency Program, Boston, MA, United States. Electronic address: anazaria@bidmc.harvard.edu.
authors.forename: Ara
authors.initials: A
authors.lastname: Nazarian
authors.affiliation: Beth Israel Deaconess Medical Center, Boston, MA, United States. Electronic address: jykwon@bidmc.harvard.edu.
authors.forename: John Y
authors.initials: JY
authors.lastname: Kwon
mesh_terms: D016512:Ankle Injuries / Q000601:surgery*; D000843:Ankle Joint / Q000033:anatomy & histology / Q000601:surgery*; D001863:Bone Screws; D001864:Bone Wires; D002102:Cadaver; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D016059:Range of Motion, Articular; D053441:Suture Anchors
keywords: Ankle ROM; Ankle fracture; Biomechanical Study; Cadaveric study; Syndesmotic malreduction; Syndesmotic overtightening; Syndesmotic screw