| Objective Evaluating the feasibility of the posterior C2 pedicle screw placement(C2 PSP)via the Multi-planar Reconstruction of Helical Computed Tomography(MPR).Methods 250(500 sides)patients underwent head and neck computed tomography angiography examination,the results were as follows after MPR:The bony parameters:pedicle diameter(D),isthmus height(T),internal height(H)and the arterial parameters:(1)medial shifting:lateral(L),neutral(N),medial(M);(2)the degree of riding:below(b),within(w),above(a).To determine the prevalence of narrow pedicles,high-riding vertebral arteries(HRVA)and the subtypes of IAVA in the general population,and χ2 test was used for statistical analyses between narrow pedicles、HRVA、IAVA and the C2 vertebral arteries groove(C2 VAG)injury.Results There were 14.40% narrow pedicles and 24.60% HRVA,there was a significant difference between narrow pedicles and HRVA(χ2=141.984,P<0.001);the three subtypes of IAVA,the L-b(17.80%)、N-w(30.40%)、M-a(15.60%),were more than the others and constituted more than 60%.When it comes to the simulation of the C2 PSP inserting,the incidence of C2 VAG injuries was 19.40%(97/500).With narrow pedicle and HRVA patients,the C2 VAG injuries incidence is higher than without narrow pedicle and HRVA patients(P < 0.001).The prevalence of narrow pedicles and HRVA occurring simultaneously in the general population,58(58/500,11.60%).There was statistical significance difference between narrow pedicles and HRVA and the C2 VAG injuries in the types of IAVA(P<0.001),the subtypes of IAVA M-a consisted most of its injuries,which account for 55.56%,46.34% and 48.45% respectively.Conclusion Most of the C2 VAG injuries were happened in narrow pedicles,HRVA or IAVA M-a type patients,Therefore,MPR can be used to comprehensively evaluate osseous and arterial parameters,which will provide anatomy foundation to the screw placement of C2 pedicles. |
