颈椎椎弓根螺钉瞄准器的研制与实验

目的探讨在颈椎椎弓根螺钉内固定中使用瞄准器的准确性与可行性.方法8具颈椎标本,经CT平扫测量C3～C7各椎弓根轴线的内偏角度及在关节突上的投射点,X线双斜位片测量椎弓根轴线的头/尾偏角度及在关节突上的投射点.将标本分为两组,用2.8 mm×30 mm的螺钉置入,第1组用手工按定位点及角度直接置入,第2组采用自行研制的可三维调节角度并可术中矫正的颈椎椎弓根螺钉瞄准器置入螺钉.结果第1组C3～C7共40枚螺钉,13枚螺钉位于椎弓根内,9枚穿破椎弓根,但未侵犯临近结构,18枚有脊髓、神经根或椎动脉损伤;第2组C3～C7共40枚螺钉,36枚位于椎弓根内,4枚穿破椎弓根,但未侵犯临近结构.两组比较差异具有显著性(P＜0.01).结论在颈椎椎弓根螺钉的置钉过程中使用瞄准器有利于提高置钉的准确性,可进入临床使用.

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). CONCLUSION: In the cervical spine, transpedicular fixation using an aiming device can improve the accuracy and safety during operation.