A biomechanical comparison between cortical bone trajectory fixation and pedicle screw fixation.
OBJECTIVE
There have been several reports on the pullout strength of cortical bone trajectory (CBT) screws, but only one study has reviewed the stability of functional spine units using the CBT method. The purpose of this study was to compare vertebral stability after CBT fixation with that after pedicle screw (PS) fixation.


METHODS
In this study, 20 lumbar spine (L5-6) specimens were assigned to two groups: the CBT model group that underwent CBT screw fixation (n = 10) and the PS model group that underwent pedicle screw fixation (n = 10). Using a six-axis material testing machine, bend and rotation tests were conducted on each model. The angular displacement from the time of no load to the time of maximum torque was defined as range of motion (ROM), and then, the mean ROM in the bend and rotation tests and the mean rate of relative change of ROM in both the bend and rotation tests were compared between the CBT and PS groups.


RESULTS
There were no significant differences between the CBT and PS groups with regard to the mean ROMs and the mean rate of relative change of ROMs in both the bend and rotation tests.


CONCLUSIONS
Intervertebral stability after CBT fixation was similar to that after PS fixation.
Department of Mechanical Engineering, Mie University, Tsu City, Mie, Japan.
Hiroki
H
Oshino
Department of Spinal Surgery and Medical Engineering, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu City, Mie, 514-8507, Japan.
Toshihiko
T
Sakakibara
Department of Mechanical Engineering, Mie University, Tsu City, Mie, Japan.
Tadashi
T
Inaba
Department of Mechanical Engineering, Mie University, Tsu City, Mie, Japan.
Takamasa
T
Yoshikawa
Community-University Research Cooperation Center, Mie University, Tsu City, Mie, Japan.
Takaya
T
Kato
Department of Spinal Surgery and Medical Engineering, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu City, Mie, 514-8507, Japan. ykasai@clin.medic.mie-u.ac.jp.
Yuichi
Y
Kasai
D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology*; D003670:Deer; D008159:Lumbar Vertebrae / Q000473:pathology / Q000601:surgery*; D008297:Male; D008422:Materials Testing / Q000379:methods / Q000592:standards*; D065289:Pedicle Screws / Q000592:standards*; D016059:Range of Motion, Articular / Q000502:physiology