枢椎椎弓根螺钉进钉点的解剖定位研究

目的研究枢椎下关节突与枢椎椎弓根的位置关系,建立以枢椎下关节突为解剖标志的枢椎椎弓根螺钉进钉定位技术。方法取50套成人干燥枢椎标本,测量枢椎椎弓根的内、外缘和枢椎下关节突的内缘、中点、外缘分别与正中矢状线的垂直距离,以及枢椎椎弓根的宽度与高度。通过分析测量值间的关系,建立枢椎椎弓根螺钉的进钉定位技术。结果枢椎下关节突内缘在枢椎椎弓根内缘的外侧(3.67±0.41)mm处,枢椎下关节突中点在枢椎椎弓根外缘的外侧(1.15±0.44)mm处。建立了两种以枢椎下关节突为标志的进钉点定位方法,进钉点A位于枢椎下关节突内上象限,即中心点内、上各2mm处;进钉点B位于经枢椎下关节突内缘的纵垂线与枢椎下关节突中上1/4水平线的交点。结论枢椎下关节突与枢椎椎弓根间存在较恒定的解剖位置关系,枢椎下关节突可作为术中判断枢椎椎弓根位置和确定枢椎椎弓根螺钉进钉点的简易解剖学标志。

Anatomic evaluation the entry point of C2 pedicle screw

OBJECTIVE: To study the relevant position of C(2) pedicle to C(2) inferior articular process, set up a technique of C(2) pedicle screw placement with the inferior articular process of axis as an anatomic landmark. METHODS: Fifty C(2) bone specimens were used to measure the distance from the sagittal midline to the medial border, the midpoint and the lateral border of C(2) inferior articular process or C(2) pedicle; the width and the height of the C(2) pedicle were also evaluated. The anatomic relation between the measurements data of C(2) pedicle and that of C(2) inferior articular process were analyzed, and the technique of C(2) pedicle screw fixation was established. RESULTS: The medial border of C(2) inferior articular process was averaged (3.67 +/- 0.41) mm lateral to that of C(2) pedicle, and the midpoint C(2) inferior articular process was averaged (1.15 +/- 0.44) mm lateral to the lateral border of C(2) pedicle, respectively. Using the C(2) inferior articular process as landmark, two techniques was established for C(2) pedicle screw placement. The entry point of method A was located in 2 mm medial and superior to the central point of C(2) inferior articular process; the entry point of method B was at the crossing point of the medial border C(2) inferior articular process with the superior quarter of C(2) inferior articular process. CONCLUSIONS: There is a steady anatomic relation between C(2) pedicle and C(2) inferior articular process, the C(2) inferior articular process could be as a convenient key anatomic landmark to determine the location of C(2) pedicle and the position of C(2) pedicle screw entry point.