| BackgroundThe cervicothoracic junction plays a very important role as the transition point of cervical vertebra to thoracic vertebra.The osteonosus in this area usually causes neurological symptoms below the cervical plane,which can directly lead to paraplegia in severe cases.In order to relieve the compression of the spinal cord or nerve root,restore the normal anatomical sequence of the spine,and reconstruct its stability,a robust posterior screw-rod system is usually selected to deal with the injuries of the subaxial cervical spine and cervicothoracic junction,where posterior fixation is often performed to the C7.The lateral mass of the C7 is thin and narrow and has a large articular surface angle,so the lateral mass screw fixation is not stable.In addition,there are few vertebral arteries passing through the foramen of the transverse process of C7,and there is almost no possibility of injuring the vertebral artery.Therefore,pedicle screw for subaxial spine has good three-dimensional stability and pull-out resistance and has become the preferred method to the fixation of C7.Because of the great difference in the anatomy between C7 and C3-6,most of the existing methods of pedicle screw placement for subaxial cervical spine are based on the anatomical landmarks of C3-6,so there is no individual method of pedicle screw placement for C7 at present.Based on a large number of clinical observation and analysis,our group proposed a method of C7 pedicle screw placement through constant anatomical structure,and verified the accuracy of cervical spine specimens.The experimental results show that this method can pass through the central axis of the pedicle without destroying the pedicle cortex.It is simple and easy to operate,but its clinical effect still needs to be verified by surgery.ObjectiveTo evaluate the safety,effectiveness and repeatability of the method of C7 pedicle screw placement proposed by our group,the method was applied in clinical operation on the basis of experimental accuracy.MethodsBased on the observation and analysis of clinical data,a method of screw placement for the C7 pedicle was proposed.In this method,two anatomical landmarks were identified on the posterior lamina of C7,namely point A(the intersection of the edge of C7 lamina and the medial margin of superior articular process),point B(the intersection of the lateral margin of inferior articular process and the medial margin of transverse process).The connecting line between the two points was named as line G.Placing the C7 pedicle screw at the middle and outer 1/3 point of the G-line can pass through the central axis of the pedicle exactly and not easily penetrate the pedicle cortex.Therefore,this point is named L-point,that is,the C7 pedicle screw placement point.To retrospectively analyze the patients who used the pedicle screw placement method for posterior C7 internal fixation.The subaxial cervical spine and internal plants were reconstructed by CT reconstruction technology.The length and diameter of the screw used on the pedicle of C7 were counted.The angle between the horizontal plane of the upper C7 endplate(?)and the sagittal plane of the vertebral body(?)was calculated to determine the position of the screw.Grading(screw completely located in the pedicle cortex is grade 0;screw penetrates the pedicle cortex but not more than 1.5mm in the excess part is grade 1;screw penetrates the pedicle cortex and exceeds 1.5mm in the excess part,but no neurological dysfunction related to screw placement is grade 2;screw penetrates the pedicle cortex beyond 1.5mm and combined with neurological dysfunction related to screw placement is grade 3).Statistics of patients VAS score,JOA score,improvement rate and complications before and after operation were used to evaluate the safety and effectiveness of the C7 pedicle screw placement technology.ResultsA total of 27 patients with C7 pedicle screw fixation were enrolled.18 patients were followed up successfully.Statistical results showed that 35 C7 pedicle screws were used,all of which achieved bone fusion.29 screw placements were grade 0,6 screw placements were grade 1,no grade 2 or 3 screw placement.There was no statistical difference in the length,diameter,? or ?.The VAS scores before,1 week after and 3 months after operation were 3.72±1.78,2.67±1.37,0/1.25 respectively.There was statistical difference in the VAS scores before and 1 week and 3 months after operation(P < 0.05).The JOA scores before,1 week after and 6 months after operation were 7.22±2.53,12.94±1.51 and 15.11±1.28 respectively.The improvement rates of JOA 1 week after and 6 months after operation were(58.25±11.88)% and(80.23±13.49)%.Statistical analysis showed that 6 cases of complications after operation included cerebrospinal fluid leakage,but all of them were caused by the opening of dura due to resection of intradural tumors.No complications related to C7 pedicle screw placement occurred.No complications such as wound hematoma and infection occurred.ConclusionIn this study,the C7 pedicle screw placement technology proposed by our research group was clinically validated.It is believed that the technology is simple,safe,effective and repeatable. |
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