The Feasibility And Parameters Of Placement In Anterior Transpedicular Root Screws By Mimics Software

Objective To observe the feasibility and parameters of placement in anterior transpedicular root screws(ATPRS)with virtual screw,by Mimics software establishing 3D reconstruction model of C3-7.Methods From January 2016 to May 2017,50 cases of cervical CT scan without obvious abnormalities,There were 24 males and 26 females,20-49 years old,mean age of 32.1 years.Mimics software is imported in DICOM,3D reconstruction is carried out.First,measure the date on CT and Mimics for anterior vertebral body height in mid-sagittal plane,vertebral body depth in mid-sagittal plane,vertebral body width in transverse plane,left transverse and sagittal pedicle angle,left pedicle axis length.Second,left anterior vertebral of C3-7 were divided into nine areas in coronal plane,then insert virtual screw with diameter of 4.5mm.The head of screw is located at the intersection of the posterolateral margin of the vertebral body and the axis of the pedicle in horizontal plane.Also at the lower edge of the pedicle in sagittal plane.The caudal end of screw is located at the center of nine areas.Record the length of each area of the screws(L),the angle in horizontal plane(α)and in sagittal plane(β);the percentage of screw exposed to the outside of the vertebral body(EL%:exposed length),individually.Meanwhile,The above data were statistically analyzed.Results Compare data from CT and software,there were no statistical differences in two-dimensional data(P>0.05).The area may be inserted more than 18 mm,was zone 7 of C3-6 and zone 1、4 and 7 of C7 in males;also zone 7 of C5-7 in females.Measure the angle in horizontal plane,there were no statistical differences in the same horizontal plane(P>0.05).Measure the angle in horizontal plane,there were no statistical differences in the same sagittal plane(P>0.05).The percentage of exposed screws in C3-7 of zone 1、4 and 7 was smallest..The percentage of exposed screws was more than 75% of zone 8、9 in C3,zone 9 in C4-6 in males and females.Conclusions Mimics has high credibility.The screw of 18 mm can be inserted in C3-7 with ATPRS in males,it can be inserted in C5-7 in females.It is indicated that the ATPRS is a feasible internal fixation technique.It has the advantages of longer screw length,wider range of insertion and safety.