Lab Anim Res.  2013 Sep;29(3):138-147.

Morphometrical dimensions of the sheep thoracolumbar vertebrae as seen on digitised CT images

Affiliations
  • 1Large Animal Clinic for Surgery, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany. mahmoud.mageed@hotmail.com
  • 2Department of Surgery and Anaesthesia, Faculty of Veterinary Medicine, University of Khartoum, Shambat, Sudan.
  • 3Microsurgery and Animal Models Core, Translational Centre for Regenerative Medicine, University of Leipzig, Leipzig, Germany.
  • 4Department of Neurosurgery, BG Hospital Bergmannstrost, Halle, Germany.

Abstract

The sheep spine is widely used as a model for preclinical research in human medicine to test new spinal implants and surgical procedures. Therefore, precise morphometric data are needed. The present study aimed to provide computed tomographic (CT) morphometry of sheep thoracolumbar spine. Five adult normal Merino sheep were included in this study. Sheep were anaesthetised and positioned in sternal recumbency. Subsequently, transverse and sagittal images were obtained using a multi-detector-row helical CT scanner. Measurements of the vertebral bodies, pedicles, intervertebral disc and transverse processes were performed with dedicated software. Vertebral bodies and the spinal canal were wider than they were deep, most obviously in the lumbar vertebrae. The intervertebral discs were as much as 57.4% thicker in the lumbar than in the thoracic spine. The pedicles were higher and longer than they were wide over the entire thoracolumbar spine. In conclusion, the generated data can serve as a CT reference for the ovine thoracolumbar spine and may be helpful in using sheep spine as a model for human spinal research.

Keyword

Ovine; spine anatomy; animal model; reference values; computed tomography

MeSH Terms

Adult
Humans
Intervertebral Disc
Lumbar Vertebrae
Models, Animal
Reference Values
Sheep
Spinal Canal
Spine
Tomography, Spiral Computed

Figure

  • Figure 1 Transverse CT image obtained at the cranial aspect of L5 of a 2-year-old clinically normal female Merino sheep illustrating the measurements obtained for T2 through L6. Left is right. The measurements of interest obtained for each of the thoracolumbar vertebrae were vertebral body width (VBW; widest distance between the lateral borders of the vertebral body), and vertebral body depth (VBD; distance between dorsal and ventral borders of vertebral body).

  • Figure 2 Sagittal CT image with measurements on the T9 in a two-year-old female Merino sheep illustrating vertebral body height at dorsal border (VBHd; distance between the most dorsocranial and the most dorsocaudal point of the same vertebral body), vertebral body height at ventral border (VBHv; distance between the most ventrocranial and the most ventrocaudal point of the same vertebral body) and disc thickness (DT; distance between cranial and caudal vertebral epiphyses of adjacent vertebrae). Cranial is to the left.

  • Figure 3 Transverse CT images obtained at the level of T7 of the same sheep as in Figure 1. Left is right. Spinal canal width (SCW; widest distance between axial cortices of pedicles), spinal canal depth (SCD; distance between dorsal border of vertebral body and lamina at vertebrae midline) and transverse process length (TPL; distance between tips of transverse processes).

  • Figure 4 Transverse CT image obtained at the cranial aspect of L5 in a two-year-old female Merino sheep. Left is right. Pedicle length (PDL; distance between dorsal vertebral cortex and junction between ventral border of transverse process and vertebral body because of the vertebrae type II [the pedicle locates dorsal to the transverse process]),pedicle width (PDW;widest distance between the axial and abaxial border of pedicle), pedicle axis length (PAL; distance from dorsal vertebral lamina cortex to midpoint of ventral vertebral cortex, pedicle axis angle (PAA; angle between PAL and vertebral midline) and sagittal midline (ML; line bisects the vertebrae to equal halves).

  • Figure 5 Transverse CT image obtained at the level of T5 in a two-year-old female Merino sheep. Left is right. Pedicle length (PDL; refers to pedicle type I, which is located ventrally to the transverse process), sagittal midline (ML; line bisects the vertebrae to equal halves) and PL (perpendicular line to vertebral midline at the level of ventral border of the spinal canal).


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