摘要
目的：评价X线片判断颈椎椎弓根螺钉植入孔道的准确性。
材料和方法：正常干燥C3~C7人尸体骨，共8个。正常人尸体颈椎标本C3~C7共8具，保持椎体连续性。直径2.5mm的钻头72枚。用HITACHIDHF-155H X线机，日本产。干燥及连续性颈椎标本随机编号。我们采用王东来法[12]以颈椎关节突背面中点为原点建立平面直角坐标系，进针点为Ｃ3~Ｃ6在外上象限的中点，Ｃ7在Ｙ轴上，上关节面下缘略下方；进针方向为Ｃ3~Ｃ6与矢状线呈40°~50°，Ｃ7与矢状线呈30°~40°夹角，平行相应节段椎体上终板。将2.5mm钻头安装在手摇钻上，沿椎弓根轴线钻入椎弓根，然后向内、外偏斜分别穿破内、外侧椎弓根皮质，以上均不穿破椎体前方皮质，依次完成各椎体。将钻头分别插入随机选择三种位置（穿破内或外侧椎弓根皮质，位于椎弓根内），中的一种，左侧钻头尾部缠绕钢丝，放置在固定椎体夹具上。摄片后，拔出钻头再分别插入每个椎弓根余下的二个位置，以保证每侧椎弓根的三个孔道均插入过。在上述的二个位置再分别摄正、侧位片及双斜位45°X线片。这样每个椎弓根的三个孔道都有正、侧、双斜位45°X线片。每次插入并摄片之前，操作者记录下穿入孔道的位置，此记录作为判断读片正误的金标准。请6名医生，分成2组。一组为从事临床工作15年以上的高年资骨科医生3名；另一组为从事临床工作不足5年的低年资骨科医生3名。将X线片随机任意排列。每位医生独立读片，将判定结果与金标准做比较，选用敏感性、特异性、阳性预测值和准确性，作为确定检测
方法效果的评价指标。应用方差分析对双斜位45°X线片和正、斜位片、单纯斜位45°X线片和医生的年资而得出的准确性的差异进行比较。所有统计计算应用SAS软件包完成。
结果：无论高、低年资医生，还是干燥和连续性椎体，在判断穿破内、外侧皮质和位于椎弓根内时，双斜位45°X线片结合的敏感性、特异性、阳性预测值及准确性均高于正、斜位片及单纯斜位45°X线片，均有显著性差异（P<0.05）。
讨论：颈椎椎弓根螺钉内固定技术远未普及。其临床应用受到限制的主要原因不仅是该技术有潜在的神经、血管损伤的风险大，而是目前临床上尚没有既简单，方便又能准确的检测术中螺钉位置的方法。我们采用术中X线影像定位的方法判断椎弓根螺钉植入的准确性，采用钻头作为定位针，是因为钻头上的螺纹所标示的位点不会因钻头的倾斜而改变。在斜位X线片上，利用钻头上的螺纹来确定椎弓根狭部的那一点，通过这一点与椎弓根椭圆形影的关系来判断植入准确性。
无论是高、低年资医生，无论是内、中、外侧，双斜位45°X线片结合的敏感性、特异性及阳性预测值及准确性均高于正、斜位X线及单纯斜位45°X线片。而椎弓根内侧皮质邻近脊髓，外侧皮质邻近椎动脉、神经根，因此，内、外侧皮质受破坏就可能伤及这些组织，造成严重后果。由于双斜位45°X线片结合判断的准确性高，我们可以及时判断出来。减少手术的并发症的发
生。
因为根据解剖测量结果，Ｃ3~Ｃ7椎弓根的外展角度平均分别42°、45°、42°、38°、36°左右[11]。而钻头只有在椎弓根内，且与双斜位45°X线角度一致时在斜位片上位于椎弓根椭圆型影中央。但是，投照的射线束很少与定位针的纵轴平行，使定位针在斜位X线片的影像呈一条线，而不是落在椎弓根内或椎弓根外。所以判定的准确性没有双斜位45°X线片结合的准确性高的原因。又由于在斜位X线片上，钻头难以分辨螺纹，这样就观察钻头是否突破椭圆型影来判断，所以比单纯斜位45°X线片判定的准确性高的原因。在正位X线片上椎弓根峡部内、外侧重叠, 峡部的椭圆形影显示不清。又由于我们破坏了椎弓根的内侧皮质和外侧皮质，椎弓根椭圆形影更加显示不清，所以正、斜位X线片判定的准确性没有双斜位45°X线片结合的准确性高的原因。
在斜位X线片上，例如：左前斜位，左侧钻头位于椎弓根之内，而在右前斜位片上钻头明显突破椎弓根的椭圆形影，位于外侧。因此，在临床中我们强调要将左、右斜位片结合起来。
通过本实验我们总结出穿破椎弓根外侧皮质90.48%是钻头和另一侧前端和尾端方向一致，而穿破椎弓根内侧皮质100%是钻头和另一侧方向交叉。这样在临床中判断螺钉位置有一定的参考价值。但是，并不是钻头方向一致和方向交叉均穿破椎弓根外、内
侧皮质，位于椎弓根正中钻头方向不确定。在本实验中，熟练掌握椎弓根影像学知识可以准确、快速判定螺钉位置，缩短手术时间，减少术中感染机会。
结论：X线片较准确地判断出椎弓根螺钉的位置，双斜位45°X线片结合优于正、斜位X线片和单纯斜位45°X线片。所以在术中只要摄双斜位45°X线片就能准确地判定出椎弓根螺钉的位置。此方法简单，易于判断，而且又节省了手术时间，同时价格也便宜，又是一种非常经济的方法。
Objective: To assess the accuracy of cervical pedicle screw placement by x-ray film in A-P,45°oblique view, bilateral 45°oblique view.
Material and methods: 8 dry natural cervical centrums of cadaver, 8 cadavers’ cervical centrums (C3-C7), keep the continuity .72 aiguilles with 2.5 mm diameter , HITACHIDHF-155H X-ray emitter made in Japan.8 dry natural C3-C7 of cadaver and 8 cadavers’ cervical centrums were numbered by random.We used Wang Donglai’s method which as origin as the midpoint of posterior cervical vertebra’ arthral tuber to set up the reference frame. The point of placing the screw was select at the midpoint of superior outer quadrant. At C7, we choose the point of placing the screw on the Y axis, superior joint facet. The angle at C3-C6 is 40°-50 °at sagittal plane, at C7 is 30°-40°, paralleling to the endplate. Put the 2.5mm aiguille on the brace and bit, get into the pedicle along the axis, and drill the inner and outer cortex respectively. All of them didn’t destroy the anterior cortex of vertebra. Put the aiguille into the one of the hole random. The left aiguille was twisted with steel wire, and fixed on the a homemade clamp, took the A-P,45°oblique films. When take the films, we used a protractor in order to make the endplate plumb the horizon. When took the A-P, lateral and bilateral 45°oblique films,
we made an angle between the maker and horizon. After took a photo, we pulled the aiguille out, then put it into other holes in order to ensure each pole was inserted with the aiguille, took the radiograph. Before took the radiograph, we had noted the golden criterion. Ask 6 doctors divided into 2 groups. One is made up of 3 high-grade doctors who worked about 15 years. The other is made up of 3 low-grade doctors who worked under 5 years. Put the radiograph random, and asked the doctor read the radiograph lonely, judged the position of the screw, then filled the table. We contrasted the result with the golden criterion, used the sensitivity, different, positive predict result and accuracy as the guild line. Then we contrasted the result made by two groups with analysis of variance (ANOVA). All those data was calculated by SAS statistic software.
Result: Not only high-grade doctors, but also low-grade doctors, not only dry cervical centrums but also continual cervical centrums, when doctors assessed whether the inner or outer cortex was destroyed, there is significant difference between A-P, 45°oblique view, and bilateral 45°oblique view at sensitivity, different, positive predict result and accuracy. Anterior is higher than posterior. (P<0.05)
Discussion: The use of cervical pedicle screw fixation in clinical was reported inside and outside, but no popularization. The major reason is not only the potential danger of nerve and vein, but also there isn’t a simple, convenient and veracious method to assess the
screw’s position. We use the aiguille as the localizer because the location on the aiguille will not change when the aiguille inclined. We made certain point at the aiguille which through the pedicle isthmus. Through judge the relationship between the point and the elliptoid shadow, we presume the accuracy of the cervical screw.
Not only high-grade doctors, but also low-grade doctors, the accuracy was higher through A-P film and single 45°oblique view when justify whether the inner or outer cortex was destroyed ,or in the pedicle. Because the inner cortex is closed to spine cord and outer cortex is closed to artery and nerve root, when outer or inner cortex is destroyed, these tissue may be injured and serve result. Once we find the inner or outer is gone wrong, because the higher accuracy, we can judge and change the direction of the localizer in time, avoid positioning the screw into the wrong way. These maybe avoid the complication of the operation.
Because according the result of anatomy measured, the pedicle of C3-C7s’ abducent angles is about 42°,45°,42°,38°,36°.When the aiguille in the pedicle and parallel to the
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