Morphological classification of CT reconstruction of the narrowest part of pediculoisthmic component / 中国组织工程研究

ABSTRACT

BACKGROUND:It has been suggested that CT multiplanar reconstruction should be performed prior to the placement of axial pedicle screws to determine the anatomy of the C2 pedicle in each patient,to design the appropriate screw locus and diameter,and to evaluate the feasibility of screw placement to reduce the incidence of surgery-related complications. OBJECTIVE:To evaluate the feasibility of axis pedicle screw placement by morphologic classification of pediculoisthmic component with CT multiplanar reconstruction. METHODS:The CT data of 200 patients(400 axial pedicle screws)with cervical spine were retrospectively studied by using Siemens Syngo.Via software.According to the direction of the axis of the pedicle,the CT multiplanar reconstruction positioning line was adjusted to reconstruct the sectional image of the narrowest part of the pediculoisthmic component.According to its morphological characteristics,the narrowest part of the pediculoisthmic component was divided into three types:type 1,"hook"type:Type 1a outer diameter width(a1)>0.4 cm,type 1b outer diameter width(a1)≤0.4 cm;type 2,"like circle/ellipse"type;type 3,"horizontal ellipse"type.The outer diameter width of the narrowest part of pediculoisthmic component(d1),medullary cavity width(d2),outer diameter height(a1),and medullary cavity height(a2)were compared among the three types,and the feasibility of pedicle screw placement of the three types was evaluated. RESULTS AND CONCLUSION:(1)A total of 400 axial pedicles included 269 cases of type 1,130 cases of type 2,and 1 case of type 3.(2)The mean external diameter height between types 1 and 2 was not significantly different(P>0.05).The mean medullary cavity height,mean outer diameter widths,and mean medullary cavity width were significantly different(P<0.001).There were 42 cases(15.6%)of type 1 and 0 cases(0.00%)of type 2 with mean external diameter width≤0.4 cm,and the difference was significant(P<0.001).There was only one case of type 3,whose external diameter height,medullary cavity height,outer diameter width and medullary cavity width were 1.20 cm,0.84 cm,0.64 cm and 0.31 cm,respectively.(3)These results confirm that axial pedicle screws can be safely inserted in patients with types 1a,2 and 3,which requires no further measurement and assessment.Pedicle screw insertion should be performed with caution in type 1b patients.Therefore,in type 1 patients,the width of the narrowest outer diameter of the pediculoisthmic component should be further measured to evaluate the feasibility of axial pedicle screw placement.