Korean J Pain.  2014 Jul;27(3):253-259. 10.3344/kjp.2014.27.3.253.

Morphologic Diversities of Sacral Canal in Children; Three-Dimensional Computed Tomographic Study

  • 1Zeropain Clinic, Seoul, Korea.
  • 2Seoul Pain Clinic, Seoul, Korea.
  • 3Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea. hiitsme@snubh.org


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.
Three-dimensional computed tomographic images were analyzed. The data from the images included fusion of the sacral vertebral laminae and the sacral intervertebral space existence of the sacral cornua and 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 > or = 50% of the distance between the cornua).
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.
The sacral canal has various anatomical variations in children. Careful attention must be paid to identify the correct anatomic landmark.


anatomic variation; caudal anesthesia; sacrum; three-dimensional imaging; tomography

MeSH Terms

Anatomic Landmarks
Anatomic Variation
Anesthesia, Caudal
Imaging, Three-Dimensional
Pain, Postoperative


  • Fig. 1 Three-dimensional CT image; A: distance between sacral cornua, B: distance between S4 vertebral laminae; C: sacral intervertebral space, D & E: both sacral cornua.

  • Fig. 2 Classification of the sacral hiatus by three-dimensional CT image; (A) Group I; fused S3; (B) Group II; not fused S3 and S4 laminae, distance of S3 vertebral laminae less than 50% of distance between sacral cornua; (C) Group III; not fused S3 or S4 laminae, distance of S3 and S4 vertebral laminae more than 50% of the distance between the sacral cornua. The 3 groups were classified by the fusion of the S3 or S4 vertebral laminae and the distance of the sacral vertebral laminae.

  • Fig. 3 Proportion of groups I, II and III distributed by age. The proportion of group I increase with age. (A) including all study patients (P = 0.040), (B) excluding cerebral palsy patients (P = 0.032).


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