title: Morphometric measurement of the cervical spine for minimally invasive pedicle screw fixation using reverse engineering and three-dimensional reconstruction.
abstract: BACKGROUND
  Percutaneous cervical pedicle screw fixation has been proven to be an effective method of cervical screw instrumentation, which has the advantages of less invasiveness and low blood loss. Emerging evidence has indicated that the cervical spinous process plays an important role in percutaneous spine surgery. However, there is a limited amount of information on the fundamental research of pedicle and its associated imaging parameter measurement. The purpose of this study was to measure the anatomic data of the pedicle screw channel (PSC) using reverse engineering and three-dimensional reconstruction, and also to discuss the three-dimensional relationship between the cervical spinous process and the pedicle screw channel.
  
  
  METHODS
  Twenty adult subjects (10 males, 10 females, age range 19-46 years) were studied using the method of three-dimensional CT reconstruction and reverse engineering. The centrum was divided into 10 equal parts from front to back. The bisectors were defined as borderline depths of the centrum, from front to back, 100%, 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, 0% of borderline depths were presented. Then, a 3D coordinate system was constructed to measure all the data, including the radius of the inscribed circle, the length of the PSC, the insertion angle, the distances from entry point to cervical spinous process and skin depth. All the indexes were measured from 70% to 90% borderline depth.
  
  
  RESULTS
  The radius of the inscribed circles from C3to C7at 90% borderline depth were 2.94 ± 0.55 mm, 3.04 ± 0.40 mm, 3.15 ± 0.36 mm, 3.28 ± 0.47 mm, 3.89 ± 0.54 mm, respectively. The lengths of the PSC were between 25 and 32 mm. The insertion angles for 70% to 90% borderline depth were 28.33°, 34.28°, 37.92°, respectively. The relationship between the PSC and spinous process was measured as the distance from the entry point to the end of the spinous process, which were, respectively, 26.91 mm, 28.18 mm, 30.03 mm, 35.67 mm, 41.99 mm from C3to C7.The distance from the skin to the entry point of C3-7increased gradually.
  
  
  CONCLUSIONS
  The measurements of this study could provide detailed information for percutaneous cervical screw fixation. The data of the relationship between the cervical spinous process and the pedicle screw channel present valuable technical information for the design, optimization and clinical application of the aiming device for percutaneous cervical pedicle screw fixation. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Departments of Anatomy, University of South China, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Zi-Jia
authors.initials: ZJ
authors.lastname: Zhou
authors.affiliation: Spinal Surgery Department, The 169th hospital of P.L.A, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Chao-Lun
authors.initials: CL
authors.lastname: Wen
authors.affiliation: Departments of Anatomy, University of South China, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Qin-Min
authors.initials: QM
authors.lastname: Sun
authors.affiliation: Departments of Anatomy, University of South China, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Ai-Ping
authors.initials: AP
authors.lastname: Wang
authors.affiliation: Radiology Department, The 169th hospital of P.L.A, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Zheng-Guang
authors.initials: ZG
authors.lastname: Yan
authors.affiliation: Departments of Anatomy, University of South China, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.affiliation: Departments of Anatomy, University of South China, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Spinal Surgery Department, The second affiliated hospital of university of south china, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Qi
authors.initials: Q
authors.lastname: Cao
authors.affiliation: Departments of Anatomy, University of South China, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Xiao-Bing
authors.initials: XB
authors.lastname: Zhou
authors.affiliation: Departments of Anatomy, University of South China, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Tan
authors.affiliation: Departments of Anatomy, University of South China, Hengyang City, Hunan Province, 421001, PRC.
authors.forename: Yan-Bing
authors.initials: YB
authors.lastname: Li
mesh_terms: D000328:Adult; D001698:Biomedical Engineering; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D065289:Pedicle Screws; D013122:Spinal Diseases / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: cervical spine; computed tomography reconstruction; pedicle; reverse engineering; spinous process