Applied Anatomical Study On Technique Of Pedicle Screw Placement In C6 And C7

With the development of transport,the arrival of an aging society.Cervical spine injury and the incidence of cervical disease rising in recent years. In the treatment of these injuries,using the process of fixation,it was found that cervical pedicle screw fixation has its unique advantages in the application of the treatment more and more widely,such as cervical spine fracture,dislocation, inflammation,cancer,spinal deformity and instability.Biomechanical experiments have also confirmed that cervical pedicle screw fixation provided its high strength,good dimensional fixed effects and postoperative recovery.Therefore,in the reconstruction of stability of the three columns of spinal,it have wider applications than other fixation methods.Cervical pedicle is smaller than thoracolumbar pedicle,with large variation, and all the adjacent structures and organs are vital.The adjacent structures upper and lower are cervical nerve roots,the inner adjacent structures are epidural sinus, spinal cord,the anterolateral are vertebral arteries and veins.causing injuries to these structures can lead to serious consequences.So there is high accuracy requirements in screw placement.Although computer-aided three-dimensional navigation system improved the accuracy of pedicle screws,but it still has about 10% error rate.But its high price limits the wide application.The current method of pedicle screws remains bare-handed fixation,but this method still has some in screw placement errors.In recent years,with the deepening of the study,surgery of cervical spine Developed rapidly.Scholars have done a lot about methods for bare-handed fixation of pedicle screws,including entry points,screw direction and depth. anatomical landmarks in most of these methods are sagittal plane and horizontal plane。However,in clinical application,these anatomical locations are generally not intuitive,and it is difficult to detect postural changes of patients in surgery, sometimes disease damage to the vertebral body and its adjacent vertebral body,so vertebral anatomic changes occur,all the above make the surgeon less clear about accurate location of pedicle screws.Application of these methods has been less accurate.This not only reduces the success rate of surgery,increased surgical risk,but also brought great suffering to patients.Therefore,to find a simple,safe,effective and applicable methods for cervical pedicle screw fixation is of great significance.Objective:Through anatomical measurement on the corresponding structure of C6,C7 pedicle,further defined the structure of the pedicle,and provide a theoretical basis for pedicle screw placement in lower cervical spine.With the ombination of measurement results and the actual clinical encounters,for example,practical difficulties in pedicle screws placement,more risks and complications,we propose a new method for cervical pedicle placement,which is more simple,more secure, easier to master.Method:After taking 15 adult cervical specimens soaked in formalin, regardless of gender, age, rule out the deformity and damage.In which C6,C7 30 vertebrae,30 pairs of pedicle, respectively,30 pairs of pedicle screw insertion.1): Definition of Isthmus:area enclosed by the lower edge of aprocessus articularis superior,the upper edge of processus articularis inferior,the root of processus transversus, medial edge of aprocessus articularis superior and processus articularis inferior.2) Method of insertion:posterior isthmus and posterolateral isthmus intersect at a vertical line,through midpoint of processus transversus is a horizontal line,the point which the vertical line and the horizontal line intersect is the piont to place screw.Parallel to the upper endplate and through the narrowest point we insert screw under direct vision.So screws all screws were located in the pedicle.Cut the vertebrae horizontally through axial line of screws both sides, measure the follow issues with vernier caliper and conimeter:Pedicle width,Pedicle height, full length of Screw channel,angulation of screw axis and posterolateral isthmus at horizontal plane(E),angulation of screw axis and posterior Isthmus at vertical plane (F).SPSS13.0 statistical package was used for data analysis.Result:(1)Pedicle width(PW): C60.05).FSC was no significant difference between C6, C7(P>0.05).(2)Using Hierarchical cluster process of cluster analysis, The results showed that two types of E angle tends to.they are E1,E2 .The calculation of E1,E2 and F angle was no difference in C6, C7, merge statistical data. The calculation of were E1(89.61±1.24)°,E2(59.71±1.10)°,F (75.86±1.12)°. After t test,we can not believe there is difference between E1 and 90°,and difference between E2 and 60°.According to statistical results we know that at horizontal plane screw axis and posterolateral Isthmus intersect at 90 or 60 degrees.at vertical plane screw axis and posterior Isthmus intersect at (75.86±1.12)°.(3)the average of FSC is (30.83±0.91) mm.Conclusions:Isthmus as the reference point of the structure to set screw.It has advantages such as constant presence, the variation is small, and easy to reveal. posterior Isthmus and posterolateral Isthmus Intersect at a vertical line, through midpoint of processus transversus is a horizontal line,the point which the vertical line and the horizontal line Intersect is the piont to place screw. Make the angulation of screw axis and posterolateral Isthmus at horizontal plane 60°or 90°,and the angulation of screw axis and posterior Isthmus at vertical plane(75.86±1.12)°.This method is simple, safe and effective.