title: Biomechanical comparison of transpedicular versus intralaminar C2 fixation in C2-C6 subaxial constructs.
abstract: METHODS
  Biomechanical study.
  
  
  OBJECTIVE
  To compare the relative rigidity of C2 transpedicular versus intralaminar fixation with and without offset connectors in C2-C6 subaxial constructs.
  
  
  BACKGROUND
  Insufficient biomechanical data exists on C2 laminar fixation in subaxial constructs, and no study has considered C2-C6 subaxial constructs or the use of offset connectors.
  
  
  METHODS
  Six fresh-frozen cadaveric cervical spines underwent rigidity testing in the intact condition and after a destabilizing C3-C6 laminectomy. Specimens were instrumented with 20 mm pedicle and 20 mm intralaminar screws at C2, and with 14 mm lateral mass screws from C3-C6. In random order, three conditions (C2 pedicle screws, C2 laminar screws, and C2 laminar screws with offset connectors) were tested in flexion-extension, axial rotation, and lateral bending.
  
  
  RESULTS
  Laminar screws in C2-C6 constructs were equivalent to transpedicular fixation in flexion-extension (P = 0.985), were significantly more rigid than pedicle screws in axial rotation (P = 0.002), and were significantly less rigid than pedicle screws in lateral bending (P = 0.002). Laminar screw constructs were more rigid than the intact condition in all planes.
authors.affiliation: Department of Orthopaedic Surgery, George Washington University, Washington, District of Columbia, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Benke
authors.forename: Joseph R
authors.initials: JR
authors.lastname: O'Brien
authors.forename: Alexander W L
authors.initials: AW
authors.lastname: Turner
authors.forename: Warren D
authors.initials: WD
authors.lastname: Yu
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011859:Radiography; D016059:Range of Motion, Articular; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*