[Design and experiment of the pedicle aiming device for the cervical spine].
OBJECTIVE
To probe the accuracy and safety of using an aiming device in the transpedicular fixation of cervical spine.


METHODS
Eight cervical specimens were obtained. We used the computed tomography (CT) to scan C3 to C7, measured the medial angle of the pedicle, and determined the location of the pedicle projecting on the articular process. Then we took the oblique X-ray film, measured the cephalic/caudal angle of the pedicle, and determined the location of the pedicle projecting on the articular process. All the specimens were equally divided into two groups. Screws of 2.8 mm x 30 mm, were used. Specimens in one group were inserted with the transpedicular screw manually, while specimens in the other one inserted with the transpedicular screw using a self-designed aiming device that can be modulate at the three dimensions according to the angles of the pedicles.


RESULTS
The first group totally had 40 screws from C3 to C7. There were 13 screws in the pedicle, 9 violated the walls of the pedicle but not involved the adjunct structure, and 18 injured the important structure such as spinal cord, verteberal artery, or nerve root. In the other group, only 4 screws violated the walls of the pedicle but not involved the adjunct structure, and the others all in the pedicles. The difference was of statistical significance (P < 0.01).


CONCLUSIONS
In the cervical spine, transpedicular fixation using an aiming device can improve the accuracy and safety during operation.
Huang
Dong-sheng
DS
Department of Orthopaedics, the Second Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510120, China. huangdongshen18@hotmail.com
Su
Pei-qiang
PQ
Ma
Ruo-fan
RF
Li
Chun-hai
CH
Peng
Yan
Y
Liu
Shang-li
SL
D000328:Adult; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D006801:Humans; D016268:Internal Fixators; D008297:Male; D009984:Orthopedic Fixation Devices; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D013238:Stereotaxic Techniques; D013813:Therapy, Computer-Assisted; D014057:Tomography, X-Ray Computed