title: [Accuracy of related parameters to screw placement in lower cervical pedicle measured by spinal virtual surgery system].
abstract: OBJECTIVE
  To evaluate the accuracy of the related parameters measured by spinal virtual surgery system (SVSS) three-dimensional (3D) techniques by comparing with the parameters measured by multi-spiral CT (MSCT) workstation.
  
  
  METHODS
  Seven vertebrae specimens of adult men were scanned with MSCT, and the messages were sent to MSCT workstation and SVSS. The 3D image of spine was reconstructed by using volume rendering and multi-planar reformation; based on the parameter requirement of lower cervical pedicle fixation, 10 related parameters were measured. Then SPSS11.0 analyzer software was used to analyze the parameters measured by 2 systems. Between June 2009 and March 2010, 6 patients who received screw insertion in lower cervical spines were given MSCT scanning, then the messages were sent to SVSS 3D reconstruction to evaluate the situation and to collect the parameters of pedicle screw insertion.
  
  
  RESULTS
  SVSS measurement showed that 1 pedicle was clausura (C3) and the diameters of 4 pedicles in coronal view were lee than 3 mm (C4 in 1, C5 in 2, C6 in 1), which did not fit for screw insertion; the results were similar to those by MSCT measurement. A total of 66 lower cervical pedicle were measured successfully. Significant differences were found in 14 parameters as follows between 2 systems (P < 0.05): the left pedicle height of C3, the both sides pedicle width of C4, the right pedicle spongy width of C4, the left X-direction entrance of C6, the both sides Y-direction entrance of C3, total pedicle length of sagittal view in both sides pedicle of C3 and the left pedicle of C5, total pedicle length of axial view in C3 pedicles, the left pedicle of C5, and the right pedicle of C6. There was no significant difference in the other parameters (P > 0.05). In 6 clinical cases, 34 screws were inserted, the postoperative MSCT scanning showed that 30 screws were placed successfully. The rate of accuracy was 88.24%. According to the Richter's perforation classification, perforation at grade I and at grade II occurred in 2 cases (5.88%), respectively.
  
  
  CONCLUSIONS
  The accuracy of the parameters measured by SVSS is similar to that by MSCT.
authors.affiliation: Department of Orthopaedics, the First People's Hospital of Zhengzhou, Zhengzhou Henan, 450000, P.R.China.
authors.forename: Jun
authors.initials: J
authors.lastname: Cao
authors.forename: Fei
authors.initials: F
authors.lastname: He
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.forename: Qifeng
authors.initials: Q
authors.lastname: Liang
authors.forename: Zhongxin
authors.initials: Z
authors.lastname: Li
authors.forename: Zhenying
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D000293:Adolescent; D000328:Adult; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D025321:Surgery, Computer-Assisted / Q000379:methods / Q000706:statistics & numerical data*; D036542:Tomography, Spiral Computed; D014584:User-Computer Interface; D055815:Young Adult