Comparison Of Safety Between Posterior C1-C2 Transarticular And C2-Pedicle Screws Based On CT Multiplanar Reconstruction

ObjectiveTo compare the safety between C1-C2 transarticular and C2-Pedicle screws via the CT Multi-planar Reconstruction of vertebral artery CT angiography(MPR).MethodsRetrospective analysis 62 patients underwent head and neck computed tomography angiography examination.Simulate the placement of transarticular and pedicle screws using MPR,then compare the frequency of C2 vertebral artery groove(C2 VAG)violation by the two different fixation methods,and record the safe range of medial convergence angle and sagittal angle of the two ways.Based on the MPR,the general population were classified in the subset of those with narrow pedicles(NP),with high-riding vertebral arteries(HRVA)and with the different subtypes of Intra-axial vertebral artery(IAVA).The differences between NP?HRVA?IAVA types and C2 VAG violation were analyzed with the method of ?2test,and using the one-way ANOVA analysis between the angles and IAVAtypes.ResultsOverall,25% of TASP and 29%of PSP violated the C2 VAG without a significant difference between the two groups(P=0.12).Among those with HRVA,C2 VAG violation was significantly lower(p=0.03)with TAS than with PS.Among those with NP,C2 VAG violation was high in both groups but without a significant difference between the two types of screws.The subtype IAVA M-a consisted most of NP,HRVA and C2 VAG violation of two methods,which account for 44.4%,51.5%,48.6% and 53.3%respectively.There was a significant difference between NP and HRVA(P<0.001).There was also a significant difference between NP and HRVA violations to the C2 VAG(P < 0.001),as well as the C2 VAG violations,NP and HRVA between IAVA(P < 0.001).ConclusionNeither method has an inherently higher anatomic risk of C2 VAG violation.However,in the HRVA,TAS is significantly safer than PS.