下颈椎经关节螺钉植入深度的侧位X线片评价

目的 运用侧位x线片评价下颈椎经关节螺钉植入深度的安伞性.方法 采用6具新鲜颈椎标本(C1～T1),每具标本均在直视下植入下颈椎经关节螺钉(每侧4枚螺钉:C3,4、C4,5、C5,6、C6,7各1枚),分别在植入螺钉尖端穿出最后一层皮质0、2、4、6 mm时摄标准侧位x线片,将侧位X线片上椎体垂直等分为四部分,定义为1～4区,并定义椎体后缘之后相当宽度的区域为前1区.每次植入时记录螺钉尖端在X线侧位片的位置,以综合评价螺钉植入的安全性.结果 在C3,4和C4,5螺钉尖端穿出最后一层皮质0 mm时,87.5％在1区,穿出2 mm时,54.2％在1区.当螺钉尖端穿出4 mm时,75.O％在2区,穿出6mm时58.3％在3区.在C5,6和C6,7,穿出0mm时75.0％位于前1区,穿出2mm时,54.2％位于前1区;穿出4 mm时83.3％位于1区,穿出6mm时,50.0％位于2区.结论 侧位X线片町用于评价下颈椎经关节螺钉植入深度的安全性.在侧位X线片上,理想的螺钉尖端位置为C3,4和C4,5应位于1区,而在Cs,6和C6.7应位于前1区.

Lateral radiological evaluation of transarticular screw placement in the lower cervical spine

Objective To assess the value of lateral radiographs in determining the safe or hazardPUS locations of the tips of screws used in transartieular screw fixation in the lower cervical spine.Methods Six cervical spines were removed from embalmed cadavers.Four transartieular screws were placed into the lower cervieal spine at C3,4 to C6,7 both both sides for each specimen.Four screw placements under direct visualization,including placement of the screw tip staying the ventral cortex,2 mm,4 mm and 6 Bin overpenetration of the ventral cortex,were performed on each specimen.Following each placement,a lateral radiograph was taken.Each vertebral body was divided vertically into four equal zones with Zone I being most posterior,and another equal zone posterior to the posterior border of the vertebral body was defined as PreZone I.The numbers of screw tips seen in each zone were quantified for each placement.Results At C3,4 and C4,5,87.5%of the screws without perforating the ventral codex and 54.2%screws over-penetrating 2mm were found in Zone I;75.0%of the screws 0ver-penetrating the ventral cortex for 4 mm were located in Zone Ⅱ;58.3%screws over-penetrating for 6mm were noted in Zone Ⅲ.At C5,6 and C6,7,75.0%of the screws without perforating the ventral cortex and 54.2%screws over-penetrating 2mm were found in preZone I:83.3%of the screws over-penetrating the ventral cortex for 4mm were located in Zone I:50.0% screws over-penetrating for 6 mm were noted in ZoneⅡ.Conclusion Lateral radiographs may be valuable in evaluation of transartieular screw placement in the Iower cervical spine.Ideal screw tip positions on lateral radiograph for transarticular screw may be in Zone I at C3,4 and C4,5,in pre-Zone I at C5,6 and C6,7.