title: Which posterior instrumentation is better for two-level anterior lumbar interbody fusion: translaminar facet screw or pedicle screw?
abstract: OBJECTIVE
  To determine whether translaminar facet screws can provide stability equivalent to pedicle screws and whether the two posterior instrumentations have the same influence on the adjacent segments in two-level anterior lumbar interbody fusion.
  
  
  METHODS
  In a biomechanical study conducted, we used 12 fresh human lumbar spines and tested an intact spine with a stand-alone two-level anterior lumbar interbody fusion and anterior fusion augmented with pedicle screws or translaminar facet screws, under 400 N compressive preloads and 7.5 N m moments in flexion, extension, axial rotation and lateral bending, and measured the stiffness of the operated level, range of motion and intradiscal pressure at the adjacent levels.
  
  
  RESULTS
  We found a significant increase in the stiffness of the segments operated, range of motion and intradiscal pressure at the adjacent superior segment in the stand-alone two-level anterior lumbar interbody fusion during flexion, axial rotation and lateral bending, but a decrease in extension, when compared with the intact spine. The stiffness of operated segments, range of motion and intradiscal pressure in the adjacent segment are significantly higher in the two-level anterior lumbar interbody fusion augmented with posterior instrumentation than in the stand-alone two-level anterior lumbar interbody fusion. There was no significant difference between the two augmented constructs except that, at the adjacent superior segment, the intradiscal pressure was more in the construction augmented with a pedicle screw than with a translaminar facet screw in flexion.
  
  
  CONCLUSIONS
  Translaminar facet screws can provide stability equivalent to pedicle screws, but their influence on the adjacent segments is relatively lower; therefore, we suggest that translaminar facet screws be the choice in the optimal posterior instrumentation in a two-level anterior lumbar interbody fusion.
authors.affiliation: Department of Spine Surgery, The People's Hospital of Xingtai, Xingtai 054001, China.
authors.forename: Yingnuo
authors.initials: Y
authors.lastname: Hou
authors.forename: Yong
authors.initials: Y
authors.lastname: Shen
authors.forename: Zhongpo
authors.initials: Z
authors.lastname: Liu
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Nie
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D013123:Spinal Fusion / Q000295:instrumentation*