经口咽前路寰枢椎复位钢板螺钉固定强度的生物力学评价

目的对经口咽前路寰枢椎复位内固定钢板(transoralpharyngeal atlantoaxial reduction plate,TARP)进行固定螺钉拔出力实验,评估TARP系统枢椎前路椎弓根和关节突下螺钉固定的生物力学强度。方法 6例C1、C2椎体新鲜标本左右双侧均行螺钉固定,寰椎螺钉固定于侧块,枢椎螺钉分别采用椎体、前路椎弓根及关节突下固定,在生物力学实验机上通过传感器测定TARP系统寰椎和枢椎固定螺钉的最大拔出力、钉道长度,并进行统计学分析。结果寰椎(546.45±85.07)N与枢椎前路椎弓根螺钉(593.14±97.77)N的最大拔出力之间无显著性差异,枢椎前路椎弓根螺钉拔出力明显强于枢椎椎体和关节突下螺钉,枢椎关节突下螺钉(469.94±73.32)N拔出力明显强于枢椎椎体螺钉(395.15±75.07)N。结论 TARP系统枢椎螺钉固定采用前路椎弓根及关节突下固定优于枢椎椎体固定,固定安全可靠。

Biomechanic evaluation of screw pull-out strength on the axis of anterior transoralpharyngeal atlantoaxial reduction plate

Objective　To evaluate the transoral screw pull-out srength on C2 of transoralpharyngeal atlantoaxial reduction plate (TARP).　Methods　Six fresh spine specimens involving C1 and C2 (12 sides) were designed to compare screw pull-out strength  of C1 and C2. C1 screw was implanted into the lateral mass, while C2 screw was separately implanted into pedicle, vertebrae and articular process, and then the pull-out strength was tested and compared.　Results　There were no statistical difference of the screw pull-out strength between C1 lateral mass screw（546.45±85.07 N）and C2 pedicle screw（593.14±97.77 N），however, C1 lateral mass screw was stronger than C2 vertebrae screw and C2 screw underneath the articular process. The pull-out strength of C2 articular process screw（469.94±73.32N）was stronger than that of C2 vertebrae screw（395.15±75.07 N）. Conclusions: Experimentally, screw fixation transoral approach to C2 pedicle and C2 articular process of TARP is strong and safe.