C6、C7椎弓根置钉的应用解剖学研究

Applied anatomical study on pedicle screw placement in C6 and C7

目的:通过对C6、C7椎弓根的解剖学测量,设计一种以"峡部"为参考的C6、C7椎弓根置钉的方法。方法:15具经福尔马林浸泡的成人颈椎标本,不分性别、年龄,排除畸形及破坏。取C6、C7共30个椎体。先测量椎弓根宽度(PW)、椎弓根高度(PH)。将C6、C7侧块中的一部分定义为"峡部",即过上关节突下缘最低点、下关节突上缘最高点的水平线与过上关节突内外侧缘的垂线所围成区域。过上关节突内外侧缘之间划两条垂线,将"峡部"分为3等份,中份为"峡部"的后侧面,外份为"峡部"的后外侧面。取过横突根部中点的水平线与过"峡部"中外1/3垂线的交点为螺钉的进钉点。选择3.5mm直径及合适长度的螺钉,直视下沿椎弓根中轴线方向置入,使螺钉中轴线与椎弓根中轴线重合,螺钉前端穿出椎体或上终板。沿椎弓根中轴线的水平面锯开标本,可看到螺钉处在椎弓根中轴线上。螺钉在水平面上与"峡部"的后外侧面形成的角为横向角(E角);螺钉在矢状面上与"峡部"后侧面形成的角为纵向角(F角)。测量椎弓根钉道全长(FSC)。对数据进行t检验及类聚分析。结果:各指标同一节段左右侧数据比较无统计学差异(P>0.05),故将同节段左右侧数据合并后进行统计分析。C6的PW为6.12±0.78mm,PH为7.48±0.81mm;C7的PW为6.85±0.73mm,PH为8.03±0.38mm;PW与PH均为C6<C7(P<0.05),同一节段PW<PH(P<0.05)。利用聚类分析中的Hierarchical cluster过程对数据进行聚类分析,结果显示E角趋向于两类,即E1和E2。C6的E1角、E2角、F角及FSC与C7比较均无统计学差异(P>0.05),将同一指标C6与C7数据合并统计结果为FSC 30.83±0.91mm,E1角89.61°±1.24°,E2角59.71°±1.10°,F角75.86°±1.12°。结论:在C6、C7以过横突根部中点的水平线与过"峡部"中外1/3垂线的交点为螺钉的进钉点,沿椎弓根中轴线方向,在水平面上按照E角、在矢状面上按照F角进钉,行椎弓根置钉具有可行性。

Objectives： To investigate pedicle screw placement in C6 and C7, and to design C6 and C7 pedicle placement based on the isthmus as anatomic mark. Methods： 15 adult cervical specimens were used regardless of gender or age. No deformity or damage to the specimen was noted. Only the C6 and C7 specimens were used. Pedicle width（PW） and pedicle height（PH） were measured. The area below the lower edge of the superior articular process, above the upper edge of the inferior articular process, and between the medial and lateral edges of the superior articular process of the same cervical segment was defined as the isthmus respectively. The isthmus was divided into three equal parts, and two vertical lines were drawn, with the medial third as the posterior plane of the isthmus and lateral third as the posterolateral plane of the isthmus. The entry point was chosen as the intersection of the horizontal line through the midpoint of the transverse process root and the vertical line through the posterolateral plane and the posterior plane of the isthmus. The screw with a diameter of 3.5mm and suitable length was inserted to ensure the end of screw to reach the cortical bone. The axis of screws was consistent with the axis of pedicle. The angle formed by the axis of cervical pedicle screw on the horizontal plane to the posterolateral plane of isthmus was defined as the trans- verse angle of the inserted screw （E）. The angle formed by the axis of cervical pedicle screw on the sagittal plane to the posterior plane of isthmus was defined as the vertical angle of the inserted screw （F）. The two angles and the full length of pedicle screw channel（FSC） were measured. Results： There was no statistical significance as for the measurement between left side and right side at the same segment （P〉0.05）, therefore the bilateral data were combined. PW and PH of C6 was 6.12±0.78mm and 7.48±0.81mm respectively. PW and PH of C7 was 6.85±0.73mm and 8.03±0.38mm respectively. C6＇s PW and PH were less than C7＇s （P〈 0.05）, while at the same segment PW was less than PH（P〈0.05）. Using Hierarchical cluster analysis, the resuits showed that E angle tended to be two kinds as E1 and E2. The El, E2, F angle, and FSC between C6 and C7 were not significantly different （P〉0.05）, the data of the same index in C6 and C7 were combined, and FSC was 30.83±0.91mm, E1 angle was 89.61°±1.24°, E2 was 59.71°±1.10°, F angle was 75.86°±1.12°. Conclusions： The intersection of the horizontal line through the midpoint of the transverse process root and the vertical line through the mediolateral third of the isthmus can be used as the entry point for pedicle screw placement, and the screw channel should be along the pedicle axis and referenced to the E and F angle. This method is practical and reliable.