title: Analysis of PITFL injuries in rotationally unstable ankle fractures.
abstract: BACKGROUND
  Reduction and stabilization of the syndesmosis in unstable ankle fractures is important for ankle mortise congruity and restoration of normal tibiotalar contact forces. Of the syndesmotic ligaments, the posterior inferior tibiofibular ligament (PITFL) provides the most strength for maintaining syndesmotic stability, and previous work has demonstrated the significance of restoring PITFL function when it remains attached to a posterior malleolus fracture fragment. However, little is known regarding the nature of a PITFL injury in the absence of a posterior malleolus fracture. The goal of this study was to describe the PITFL injury pattern based on magnetic resonance imaging (MRI) and intraoperative observation.
  
  
  METHODS
  A prospective database of all operatively treated ankle fractures by a single surgeon was used to identify all supination-external rotation (SER) types III and IV ankle fracture patients with complete preoperative orthogonal ankle radiographs and MRI. All patients with a posterior malleolus fracture were excluded. Using a combination of preoperative imaging and intraoperative findings, we analyzed the nature of injuries to the PITFL. In total, 185 SER III and IV operatively treated ankle fractures with complete imaging were initially identified.
  
  
  RESULTS
  Analysis of the preoperative imaging and operative reports revealed 34% (63/185) had a posterior malleolus fracture and were excluded. From the remaining 122 ankle fractures, the PITFL was delaminated from the posterior malleolus in 97% (119/122) of cases. A smaller proportion (3%; 3/122) had an intrasubstance PITFL rupture.
  
  
  CONCLUSIONS
  Accurate and stable syndesmotic reduction is a significant component of restoring the ankle mortise after unstable ankle fractures. In our large cohort of rotationally unstable ankle fractures without posterior malleolus fractures, we found that most PITFL injuries occur as a delamination off the posterior malleolus. This predictable PITFL injury pattern may be used to guide new methods for stabilizing the syndesmosis in these patients.
  
  
  METHODS
  Level IV, case series.
authors.affiliation: Orthopaedic Trauma Service, Hospital for Special Surgery, New York, NY, USA warners@hss.edu.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Warner
authors.affiliation: Orthopaedic Trauma Service, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Garner
authors.affiliation: Orthopaedic Trauma Service, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Schottel
authors.affiliation: Orthopaedic Trauma Service, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Hinds
authors.affiliation: Weill Cornell Medical College, New York Presbyterian Hospital, New York, NY, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Loftus
authors.affiliation: Orthopaedic Trauma Service, Hospital for Special Surgery, New York, NY, USA Weill Cornell Medical College, New York Presbyterian Hospital, New York, NY, USA.
authors.forename: Dean G
authors.initials: DG
authors.lastname: Lorich
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016512:Ankle Injuries / Q000175:diagnosis / Q000601:surgery*; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000379:methods*; D050723:Fractures, Bone / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D015601:Injury Severity Score; D004204:Joint Dislocations / Q000175:diagnosis / Q000601:surgery; D007593:Joint Instability / Q000517:prevention & control; D017844:Lateral Ligament, Ankle / Q000293:injuries*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D064847:Multimodal Imaging / Q000379:methods*; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000502:physiology; D020127:Recovery of Function; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome; D055815:Young Adult
keywords: MRI; PITFL; ankle fracture; supination external rotation