title: Morphologic diversities of sacral canal in children; three-dimensional computed tomographic study.
abstract: BACKGROUND
  Caudal block is a common technique in children for reducing postoperative pain, and there have been several reports on the variations of the sacral canal in children. However, previous studies have mainly focused on the needle trajectory for caudal block, and there is limited information on the structural variations of the sacrum in children. The purpose of this study was to analyze the anatomic variations of sacral canals in children.
  
  
  METHODS
  Three-dimensional computed tomographic images were analyzed. The data from the images included ① fusion of the sacral vertebral laminae and the sacral intervertebral space ② existence of the sacral cornua and ③ the types of sacral hiatus. The types of sacral hiatus were classified into 3 groups: group I (fusion of S3 or S4 vertebral laminae), group II (unfused vertebral arch with the distance of the S3 and S4 vertebral laminae < 50% of the distance between the cornua), and group III (unfused vertebral arch with the distance of the S3 or S4 vertebral laminae ≥ 50% of the distance between the cornua).
  
  
  RESULTS
  A total of 143 children were included in this study. All of the sacral vertebral arches were not fused in 22 children (15.4%). Cornua were not identified bilaterally in 5 (3.5%) and unilaterally in 6 (4.2%) children. In the sacral hiatus, group II and group III were identified in 22 (15.4%) and 31 (21.7%) children, respectively.
  
  
  CONCLUSIONS
  The sacral canal has various anatomical variations in children. Careful attention must be paid to identify the correct anatomic landmark.
authors.affiliation: Zeropain Clinic, Seoul, Korea.
authors.forename: Dae Wook
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Seoul Pain Clinic, Seoul, Korea.
authors.forename: Seung Jun
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Choi
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Pyung Bok
authors.initials: PB
authors.lastname: Lee
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Young Hyun
authors.initials: YH
authors.lastname: Jo
authors.affiliation: Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Francis Sahngun
authors.initials: FS
authors.lastname: Nahm
keywords: anatomic variation; caudal anesthesia; sacrum; three-dimensional imaging; tomography