title: Morphometric comparisons between the pedicle and the pedicle rib unit in the immature Chinese thoracic spine: a computed tomographic assessment.
abstract: METHODS
  Morphology comparisons between the pedicle and pedicle rib unit in the immature spine were conducted through computed tomographic scans.
  
  
  OBJECTIVE
  To establish reference data concerning the dimensions of the pedicle rib unit for normal children.
  
  
  BACKGROUND
  Until recently, studies on extrapedicular fixation were mostly based on adults. No published study has assessed the morphology of the pedicle rib unit in the normal immature population. Establishment of the basic morphometric characteristics may be beneficial in treating immature patients with spinal disorders.
  
  
  METHODS
  Measurements were carried out on the chest computed tomography scans of the immature Chinese patients without any spinal disorder findings. The width, chord length, and transverse angle of the pedicle rib unit were obtained and compared with the corresponding pedicle index. Difference between sex groups was measured, and significant statistical correlations were carefully studied to determine potentially important clinical relationships.
  
  
  RESULTS
  The mean values and the standard deviations obtained for each thoracic segment were determined. The width, chord length, and transverse angle of the pedicle rib unit were significantly larger than corresponding pedicle measurements at all levels. Significant difference for measurements between sexes was found at some segments. Compared with the sex, age seemed to have a more significant effect on the measurements. Linear pedicle and pedicle rib unit dimensions had good correlations with age, whereas the transverse angle seemed to change little with age.
  
  
  CONCLUSIONS
  Compared with the dimensions of the immature pedicle, the significantly larger size of the corresponding pedicle rib unit provides a more ample space, which accommodates screws with larger diameters. Extrapedicular vertebral body fixation was anatomically feasible for the immature spine. The new procedure should be cautiously applied to avoid potential implant failures or a new deformity because of the growth of the immature spine.
authors.affiliation: Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, People's Republic of China.
authors.forename: Nai-Feng
authors.initials: NF
authors.lastname: Tian
authors.forename: Hua-Zi
authors.initials: HZ
authors.lastname: Xu
authors.forename: Xiang-Yang
authors.initials: XY
authors.lastname: Wang
authors.forename: Qiao-Jie
authors.initials: QJ
authors.lastname: Chen
authors.forename: Li-Cheng
authors.initials: LC
authors.lastname: Zheng
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology; D000886:Anthropometry / Q000379:methods*; D044466:Asian People / Q000208:ethnology; D001837:Body Weights and Measures / Q000379:methods; D001863:Bone Screws / Q000592:standards; D002648:Child; D002675:Child, Preschool; D002681:China / Q000208:ethnology; D005260:Female; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D012272:Ribs / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000254:growth & development*; D012727:Sex Characteristics; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods / Q000592:standards; D013904:Thoracic Vertebrae / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000254:growth & development*; D014057:Tomography, X-Ray Computed / Q000379:methods*