| Nowadays, with the increase of the high-energy injury, the atlantoaxial instability also increases by a large number. Due to the cervical spinal cord, nerve roots, vertebral artery compression and upper cervical cord stimulation caused by the atlantoaxial instability, the severe patients would be life-threatening, so most of them need immediate surgery to stabilize the cervical spine and remove the oppression, and then the atlantoaxial can be reset and remain stable. However, the upper cervical anatomical structure is complex, which location is very special and surrounded by some important blood vessels, nerves and organs, so the implement of the surgery in this area is not only difficult but also of high risk. At the same time, to some extent, the numbers of posterior transarticular screw fixation is relatively large and of good treatment in clinical use, so it is also considered as the gold standard of the treatment of atlantoaxial instability. However, there is a higher risk of injury of vertebral artery or spinal cord during the procedure of posterior transarticular screw fixation, and it is impossible to do this surgery for some patients if they have got anatomic structural variation defects such as the absent of congenital rear bone or iatrogenic removal. For this reason, there occurs a new effective surgical treatment to cope with the atlantoaxial instability----anterior C1-C2transarticular screw fixation. With the application of this kind of surgery, there is a new option and supplement for those patients who can not implement the posterior transarticular screw fixation such as the part of atlantoaxial rear defect or vertebral artery variations, what’s more, now, there already comes some cases in the clinical fields.Based on our early study of a series of basic research on anterior C1-C2transarticular screw fixation, such as the autopsy measurement science reaserch, biomechanical research, as well as some relative research on imaging studies of this kind of surgery, we form a solid theoretical foundation. On the basis of these solid theoretical foundation and the implement of long-term cervical spine surgery, our hospital had managed to do the anterior C1-C2transarticular screw fixation for21cases atlantoaxial instability from May2000to February2011, and we received a satisfactory effect after the surgery, at the same time, we further tracked, interviewed and analyzed the surgical case. The aim of this article is to analyze the safety of screw trajectory and to evaluate the treatment of the use of three-dimensional CT angiography technology (3D-CTA) measure the actual angle and the length by using the three-dimensional reconstruction measurement software on multi-planar reconstruction image, screw trajectory and vertebral artery, and the accurate distance relationship between screw trajectory and spinal canal, in order to provide the relative theoretical and clinical evidence for the later research of anterior C1-C2transarticular screw fixation.Part one the measurement of the accurate distance relationship between screw trajectory and vertebral artery of anterior C1-C2transarticular screw fixation3D-CTA multi-planeObjective:On the basis three-dimensional CT angiography (3D-CTA) of patients’ after the surgery of anterior C1-C2transarticular screw fixation and multi-planar reconstruction, we analyze the patients’ anatomical structure after the surgery, at the same time, we measure accurately between screw trajectory’s actual range and the exact distance relationship of screw trajectory and spinal canal by using the three-dimensional reconstruction measurement software on multi-planar reconstruction image. So we get an opportunity to analyze the safety of screw trajectory in anterior C1-C2transarticular screw fixation after the surgery and provide a clinical objective evidence of improving the accuracy and security of anterior C1-C2transarticular screw fixation in such kind of surgery in the future.Method:After the treatment of anterior path of atlantoaxial transarticular screw fixation and postoperative X-ray and CTA check for the21cases of atlantoaxial injury and instability patients with the application of AW three-dimensional measurement software to measure the implanted screw length, the lateral angulation angle(the screw trajectory angle between the projection of the screw trajectory in the sagittal plane into the screw point is the lateral angulation angle), the posterior angulation angle(screw trajectory into the anchor point relative coronal plane of projection of the screw channel trajectory between the angle is the posterior angulation angle), the exact distance relationship between different plane screw and vertebral artery and other21indicators. The linear data is accurate to0.1mm and the angle is accurate to0.1°. Then data were analyzed by using SPSS13.0software, the calculated mean±, standard deviation (x±s) and data (x±s) were obtained for the above measured indicators. The same project or plane around both sides of the parameters use a paired test, multiple samples use One-way ANOVA analysis of variance and LSD method to analyze the statistical test significant at alpha=0.05.Result:After the study on the anterior path of atlantoaxial transarticular screw fixation postoperative followed-up and3D-CTA multi-plane measurement, we found this group in all cases the needle point for the scope of the pedicle screw was4mm at the top of the junction between the atlantoaxial anterior arch of the lower edge and the atlantoaxial vertebral of the lateral margin. The needle point is along the lateral atlantoaxial joint central to drill the lateral mass of atlas lateral on the articular surface of cortical bone, implanted3.5mm diameter cancellous screws. The scope of the screw tract is in the sagittal plane, lateral angulation (9°～22°) with an average of17°, posterior angulation (12°～29°) with an average of21°, the screw length (19～30mm) with an average of25mm, diameter3.5mm, no vertebral artery injury. At the same time it was found the minimum distance between the surgical screws and vertebral artery vertebral artery atlas transverse foramen plane was (2.2～8.2mm) with an average of5.21mm. There was no significant difference (P>0.05) for the above data both with left and right sides.Conclusion:In the anterior path of atlantoaxial transarticular screw fixation, the insertion of the guide screw and the screw itself in the inside of the atlas block to reach the atlas transverse foramen plane need to be cautious where the distance between the screw and the vertebral artery is the least. Even so, combined with the screw channel traveling direction, the screw and the vertebral artery remained a quite a long safe distance and the vertebral artery is not easy to be accidentally injured. Studies showed that in the implementation of the surgery cases, the safe range of the screw channel is objective and accurate within which the risk of vertebral artery injury of the anterior path of atlantoaxial transarticular screw fixation is very low.Part two The relationship of exact distance between3D-CTA multi-plane measurement screw tract and spinal of the anterior path of atlantoaxial transarticular screw fixationObjective:On the basis of the anterior path of atlantoaxial transarticular screw fixation in patients with three-dimensional CT angiography (3D-CTA) and multi-plane reconstruction, the anatomical characteristics of the postoperative cases were observed. Simultaneously, the application of three-dimensional reconstruction measuring software in the three-dimensional reconstruction image has accurately measured the actual postoperative screw tract range and exact distance relationship between screw tract and spinal so as to explore whether the anterior path of atlantoaxial transarticular screw fixation is easy to cause spinal cord injury providing the relevant practical foundation for the further improvement of accuracy and safety of the anterior path of atlantoaxial transarticular screw fixation of this type.Method:After the treatment of anterior path of atlantoaxial transarticular screw fixation and postoperative X-ray and CTA check for the21cases of atlantoaxial injury and instability patients with the application of AW three-dimensional measurement software to measure the implanted screw length, the lateral angulation angle(the screw trajectory angle between the projection of the screw trajectory in the sagittal plane into the screw point is the lateral angulation angle), the posterior angulation angle(screw trajectory into the anchor point relative coronal plane of projection of the screw channel trajectory between the angle is the posterior angulation angle), the exact distance relationship between different plane screw and spinal and other19indicators. The linear data is accurate to0.1mm and the angle is accurate to0.1°. Then data were analyzed by using SPSS13.0software, the calculated mean±, standard deviation (x±s) and data (x±s) were obtained for the above measured indicators. The same project or plane around both sides of the parameters use a paired test, multiple samples use One-way ANOVA analysis of variance and LSD method to analyze the statistical test significant at alpha=0.05.Result:After the study on the anterior path of atlantoaxial transarticular screw fixation postoperative followed-up and3D-CTA multi-plane measurement, we found this group in all cases the needle point for the scope of the pedicle screw was4mm at the top of the junction between the atlantoaxial anterior arch of the lower edge and the atlantoaxial vertebral of the lateral margin. The needle point is along the lateral atlantoaxial joint central to drill the lateral mass of atlas lateral on the articular surface of cortical bone, implanted3.5mm diameter cancellous screws. The scope of the screw tract is in the sagittal plane, lateral angulation (9°～22°) with an average of17°, posterior angulation (12°～29°) with an average of21°, the screw length (19～30mm) with an average of25mm, diameter3.5mm, no spinal cord injury. At the same time it was found the minimum distance between the surgical screws and spinal vertebral artery atlas transverse foramen plane was (3.8～13.8mm) with an average of8.0mm. There was no significant difference (P>0.05) for the above data both with left and right sides.Conclusion:In the anterior path of atlantoaxial transarticular screw fixation, the insertion of the guide screw and the screw itself in the side of the atlas block to reach the atlas transverse foramen plane need to be cautious where the distance between the screw and the spinal is the least. Even so, combined with the screw channel traveling direction, the screw and the spinal remained a quite a long safe distance and the spinal cord is not easy to be accidentally injured. Studies showed that in the implementation of the surgery cases, the safe range of the screw channel is objective and accurate within which the risk of spinal cord injury of the anterior path of atlantoaxial transarticular screw fixation is very low.Part three The clinical assessment on the anterior path of atlantoaxial transarticular screw fixationObjective:To further evaluate the feasibility, safety and therapeutic effect of the operation via the treatment of atlantoaxial transarticular screw fixation on atlantoaxial joint instability patients and review patients’cases after the successful operation.Method:From May2000to Februry2011, our hospital has implemented21cases of atlantoaxial transarticular screw fixation for the atlantoaxial injury and instability patients, including15males and6females, aged from20to62years old with the average41years old. Of which14cases were traffic accident,3cases were falling down injury and4cases were wrestling with varying degrees of neck pain, stiffness and limitation of activity.19cases with spinal cord dysfunction injury,1case spinal cord complete injury(Frankel grade:A-level1case,6cases of B,7cases of C,5cases of D and1case of E) and1case of non-spinal cord injury symptom. Fresh injury was19cases and old injury was2cases. After review and follow-up of the patients, we can further evaluate the feasibility, safety and therapeutic effect of atlantoaxial transarticular screw fixation.Results:20cases of all were followed-up from5months to9years with an average of20months. The review after operation showed that all the screws were in a good position with no injury of the vertebral artery or spinal cord, no loosening and breakage for the screws and no pain for the atlantoaxial. The rate of atlantoaxial synostosis was95%. The clinical symptoms after operation were all improved by different degrades and patients all got a good recovery.Conclusion:Studies have shown that as a supplement of the posterior surgery, the anterior path of atlantoaxial transarticular screw fixation does not cause spinal cord and vertebral artery injury with the built-in screw in a safe range, which offers the patients a safe, effective and alternative surgical method. |
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