Biomechanical comparison of three different types of C7 fixation techniques: Lateral mass screw, transpedicular screw, and intralaminar screw

Jae Taek Hong, Takigawa Tomoyuki, Ranjith Udayakumar, Alejandro A.Espinoza Orías, Nozomu Inoue, Howard S. An

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Study Design. In vitro biomechanical comparison of 3 C7 posterior fixation methods. Objective. To investigate the posterior cervical construct stability afforded by this novel C7 intralaminar screw with lateral mass and transpedicular screw. Summary of Background Data. The intralaminar screw method is recently introduced and used in C7 fixation. However, no biomechanical comparisons of the C7 intralaminar screw with lateral mass screw or transpedicular screw technique have been performed. Methods. Ten fresh frozen human cadaveric C6-C7 motion segments were tested before and after 3 different types of C7 screw fixation (lateral mass screw, intralaminar screw and pedicle screw). After the kinematic study was completed, the pull out strength test for each type of C7 screw was performed. Results. To compare 3 C7 fixation techniques, normalized range of motion (ROM) of each type of screw was analyzed relative to the intact state. There were no significant differences between 3 types of C7 screws in terms of mean ROM in flexion/extension. The mean lateral bending ROM of C7 intralaminar screw construct (30.5% ± 9.2%) was significantly larger than C7 pedicle screw construct (19.2% ± 6.9%, P < 0.05). The mean axial rotation of C7 lateral mass construct (52.0% ± 27.1%) was significantly larger than C7 pedicle screw construct (38.7% ± 23.8%, P < 0.05). The pull-out strength of lateral mass screw was significantly weaker than other 2 types of C7 screw (intralaminar and pedicle screw). However there was no significant pull-out strength difference between the C7 intralaminar and C7 pedicle screw techniques. Conclusion. This study demonstrates that the pedicle screw fixation is the strongest instrumentation method for C7 fixation. However, if C7 pedicle fixation is unfavorable, in case that vertebral artery course through the C7 transverse foramen or C7 pedicle is not large enough to insert screw, the C7 laminar screw can be an alternative fixation point with similar limitation of motion except in lateral bending.

Original languageEnglish
Pages (from-to)393-398
Number of pages6
JournalSpine
Volume36
Issue number5
DOIs
Publication statusPublished - Mar 1 2011
Externally publishedYes

Keywords

  • biomechanics
  • cervical
  • intralaminar screw
  • lateral mass screw
  • pedicle screw
  • pullout testing
  • range of motion

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Clinical Neurology

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