title: Quantification of pediatric cervical growth: anatomical changes in the sub-axial spine.
abstract: OBJECTIVE
  In order to provide normal values of the pediatric sub-axial cervical spinal canal and vertebral body growth pattern using computed tomographic scans, a total of 318 patients less than 10 years old were included.
  
  
  METHODS
  The growth of the vertebral body and canal space was investigated using four different age groups. The Torg ratio (TR) was calculated and all patients were classified into a low TR group and a high TR group according to a cutoff value of 1.0. To account for spinal curvature, the C3-7 angle was measured.
  
  
  RESULTS
  Very little axial expansion and growth in height were observed (2.9 mm and 3.4 mm, respectively), and the spinal canal increments (1.8 mm) were much smaller than the dimensions of the vertebral body. The mean TR values were 1.03±0.14 at the C3 vertebral level, 1.02±0.13 at C4, 1.05±0.13 at C5, 1.04±0.13 at C6, and 1.02±0.12 at C7 in all patients. The mean sub-axial angle (C3-7) was 7.9±10.6° (range: -17-47°).
  
  
  CONCLUSIONS
  The upper sub-axial spinal canal continuously increased in size compared to the lower sub-axial spine after 8 years of age. Considerable decrements in the TR was found after late childhood compared to younger ages. Generally, there were no significant differences between boys and girls in vertical length of the cervical vertebrae. However, the axial dimension of the vertebral body and the spinal canal space varied according to gender.
authors: Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, Incheon, Korea.
authors: Ho Jin
authors: HJ
authors: Lee
authors: Department of Neurosurgery, Cheongju St. Mary's Hospital, The Catholic University of Korea College of Medicine, Cheongju, Korea.
authors: Jung Jae
authors: JJ
authors: Lee
authors: Department of Neurosurgery, St. Vincent Hospital, The Catholic University of Korea College of Medicine, Suwon, Korea.
authors: Jae Taek
authors: JT
authors: Hong
authors: Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea College of Medicine, Incheon, Korea.
authors: Jong Tae
authors: JT
authors: Kim
keywords: Pediatric cervical growth; Spinal canal space; Torg ratio; Vertebral body