title: Can a modified anterior external fixator provide posterior compression of AP compression type III pelvic injuries?
abstract: BACKGROUND
  Current anterior fixators can close a disrupted anterior pelvic ring. However, these anterior constructs cannot create posterior compressive forces across the sacroiliac joint. We explored whether a modified fixator could create such forces.
  
  
  OBJECTIVE
  We determined whether (1) an anterior external fixator with a second anterior articulation (X-frame) would provide posterior pelvic compression and (2) full pin insertion would deliver higher posterior compressive forces than half pin insertion.
  
  
  METHODS
  We simulated AP compression Type III instability with plastic pelvis models and tested the following conditions: (1) single-pin supraacetabular external fixator (SAEF) using half pin insertion (60 mm); (2) SAEF using full pin insertion (120 mm); (3) modified fixator with X-frame using half pin insertion; (4) modified fixator using full pin insertion; and (5) C-clamp. Standardized fracture compression in the anterior and posterior compartment was performed as in previous studies by Gardner. A force-sensitive sensor was placed in the symphysis and posterior pelvic ring before fracture reduction and the fractures were reduced. The symphyseal and sacroiliac compression loads of each application were measured.
  
  
  RESULTS
  The SAEF exerted mean compressions of 13 N and 14 N to the posterior pelvic ring using half and full pin insertions, respectively. The modified fixator had mean posterior compressions of 174 N and 222 N with half and full pin insertions, respectively. C-clamp application exerted a mean posterior load of 407 N.
  
  
  CONCLUSIONS
  Posterior compression on the pelvis was improved using an X-frame as an anterior fixation device in a synthetic pelvic fracture model.
  
  
  CONCLUSIONS
  This additive device may improve the initial anterior and posterior stability in the acute management of unstable and life-threatening pelvic ring injuries.
authors.affiliation: Department of Orthopaedics/Trauma, RWTH Aachen University Hospital, Aachen, Germany.
authors.forename: Richard Martin
authors.initials: RM
authors.lastname: Sellei
authors.forename: Peter
authors.initials: P
authors.lastname: Schandelmaier
authors.forename: Philipp
authors.initials: P
authors.lastname: Kobbe
authors.forename: Matthias
authors.initials: M
authors.lastname: Knobe
authors.forename: Hans-Christoph
authors.initials: HC
authors.lastname: Pape
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D016267:External Fixators; D005592:Fracture Fixation / Q000295:instrumentation* / Q000379:methods; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D008953:Models, Anatomic; D010384:Pelvic Bones / Q000293:injuries*; D010388:Pelvis / Q000293:injuries / Q000601:surgery*; D012446:Sacroiliac Joint / Q000293:injuries / Q000601:surgery