title: Biomechanical comparison of locked versus non-locked symphyseal plating of unstable pelvic ring injuries.
abstract: OBJECTIVE
  Locked symphyseal plates are utilized to provide higher levels of construct stiffness than non-locked plates. The current biomechanical study was performed to compare stiffness at the pubic symphysis between locked and non-locked plating systems.
  
  
  METHODS
  Synthetic models were utilized to represent injury to the pelvis and symphyseal plating combined with a sacro-iliac screw. Seven models were evaluated with plates and locking screws, and seven were evaluated with non-locking screws. Single limb stance was simulated, with all models loaded for 1000 cycles with 350 N applied at the sacrum. Two pairs of markers crossing the symphysis were tracked with a video-based tracking system. A coordinate system was developed to quantify motion between the pairs in three directions: medial-lateral gap, anterior-posterior shear translation, and superior-inferior shear translation. Significant differences between the plating systems were identified with t tests (p < 0.05).
  
  
  RESULTS
  Anterior-posterior shear translation varied significantly between the two plating systems. From cycles 100 to 1000, average shear translation for the non-locked and locked systems was ~0.7 and 0.3 mm, respectively, at the markers closest to the plate and 2.2 and 1.4 mm, respectively, at the markers further from the plate. Motion in the other two directions did not differ significantly between locked and non-locked models.
  
  
  CONCLUSIONS
  Locked symphyseal plating systems can provide better stability than non-locked systems for anterior-posterior shear translation. More stability could potentially reduce the risk of failure of the plate or screws.
authors.affiliation: Department of Orthopaedic Surgery, Cleveland Clinic Akron General, Akron, OH, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Godinsky
authors.affiliation: Department of Orthopaedic Surgery, Cleveland Clinic Akron General, Akron, OH, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Vrabec
authors.affiliation: Department of Research, Cleveland Clinic Akron General, 1 Akron General Ave, Akron, OH, 44307, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Guseila
authors.affiliation: Department of Research, Cleveland Clinic Akron General, 1 Akron General Ave, Akron, OH, 44307, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Filipkowski
authors.affiliation: Department of Research, Cleveland Clinic Akron General, 1 Akron General Ave, Akron, OH, 44307, USA. john.elias@akrongeneral.org.
authors.forename: J J
authors.identifier: http://orcid.org/0000-0002-9298-2915
authors.initials: JJ
authors.lastname: Elias
mesh_terms: D001696:Biomechanical Phenomena; D001860:Bone Plates; D005593:Fracture Fixation, Internal; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D008953:Models, Anatomic; D011631:Pubic Symphysis / Q000293:injuries* / Q000601:surgery
keywords: Biomechanics; Locked plating; Pelvis; Symphyseal plating