Cervical Pedicle Accompanied Vertebral Artery Dominance:Morphometric Measurement Of Cervical Pedicle And Its Surrounding Structure Using 3D-CT

Objectives:The purpose of this retrospective study was to observe the morphometric characteristics of lower cervical pedicles with dominant vertebral artery and its surrounding structure,analyse the influence to cervical pedicle screw(CPS)implantation.Methods:68consecutive patients who have dominant artery(difference of ?0.8 mm between the diameter of two vertebral artery)were selected to perform the measurements,including 42 males,and 26 females,average age was56.3±13.0(range:12-81).Left dominant was 75%,including 29 males and22 females,right dominant was 25%,including 13 males and 4females.The measurement was performed on CT workstation Advantage Workstation 4.4(AW4.4),measurements included the following: long axis length of the VA,short axis length of the VA,pedicle outer width(POW),lateral pedicle border to vertebral artery(LPVA),area of transverse foramen(ATF).Vertebral artery diameter(VAD)=(long axis length of the VA+short axis length of the VA)/2,area of VA(AVA)=?*(VAD/2)2,residuary area of transverse foramen(RATF)=ATF-AVA.Occupation ratio of TF(ORTF)=AVA/ATF*100%.Difference of all parameters between the two sides were analysed using paired t-test.The correlation between VAD and POW ? ATF were analysed using Pearson correlation coefficient.Pedicles which POW<4mm in both sides were also compared.Vertical comparison between C3 ~ C6 of all parameters were performed using One-Way ANNOA.Results: The mean VAD of dominant side was 3.8±0.5mm,non-dominant side was2.3±0.5mm.POW of dominant side and non-dominant side was5.1±1.0mm and 5.5±0.9mm,LPVA was 1.0±0.5mm and1.2±0.6mm;ATF was 29.0±6.9mm2 and 20.4±5.4mm2;RATF was17.5±5.8mm2 and 16.2±4.9mm2;ORTF was 40.5±8.5% and22.6±8.9%,respectively.Parameters comparison between the two sides:POW?LPVA of dominant side was smaller than non-dominant side,ATF?RATF and ORTF was opposite,these results was statistically significant(P<0.001).The Pearson correlation coefficient between POW and VAD was-0.094,ATF and VAD was 0.549(P<0.05),showing positive correlation between ATF and VAD,but negative correlation between POW and VAD.The proportion of POW<4mm in VA dominant side was higher than non-dominant side.C3 has the most high rate(19.1%)and decrease caudally.Vertical comparison among dominant side shows all parameters were lower at C3 ? C4 but increase slightly at C5-C6.Conclusion: 1.POW and LPVA of dominant side is smaller than non-dominant side,the percentage of POW<4mm is higher than non-dominant side.2.ORTF was bigger in dominant side;3.The risk of VAI is higher in C3?C4 than C5?C6 during CPS implantation.4.The VAI risk of CPS implantation is higher in dominant side,other internal fixation should be considered when POW<4mm.