Anatomy of large animal spines and its comparison to the human spine: a systematic review

Abstract

Animal models have been commonly used for in vivo and in vitro spinal research. However, the extent to which animal models resemble the human spine has not been well known. We conducted a systematic review to compare the morphometric features of vertebrae between human and animal species, so as to give some suggestions on how to choose an appropriate animal model in spine research. A literature search of all English language peerreviewed publications was conducted using PubMed, OVID, Springer and Elsevier (Science Direct) for the years 1980-2008. Two reviewers extracted data on the anatomy of large animal spines from the identified articles. Each anatomical study of animals had to include at least three vertebral levels. The anatomical data from all animal studies were compared with the existing data of the human spine in the literature. Of the papers retrieved, seven were included in the review. The animals in the studies involved baboon, sheep, porcine, calf and deer. Distinct anatomical differences of vertebrae were found between the human and each large animal spine. In cervical region, spines of the baboon and human are more similar as compared to other animals. In thoracic and lumbar regions, the mean pedicle height of all animals was greater than the human pedicles. There was similar mean pedicle width between animal and the human specimens, except in thoracic segments of sheep. The human spinal canal was wider and deeper in the anteroposterior plane than any of the animals. The mean human vertebral body width and depth were greater than that of the animals except in upper thoracic segments of the deer. However, the mean vertebral body height was lower than that of all animals. This paper provides a comprehensive review to compare vertebrae geometries of experimental animal models to the human vertebrae, and will help for choosing animal model in vivo and in vitro spine research. When the animal selected for spine research, the structural similarities and differences found in the animal studies must be kept in mind.

The impact of a corrective tether on a scoliosis porcine model: a detailed 3D analysis with a 20 weeks follow-up

“…While the morphology of the porcine vertebrae has been reported as being very similar to the human [25,26], little is known regarding the similarities and discordances in terms of spinal growth. Using a control group of six normal Yorkshire pigs monitored with monthly CT scan during 9 months (unpublished data), it has been determined that the normal Yorkshire thoracic vertebra grows from 2.2 to 2.6 cm during the period corresponding to the induction of the scoliosis in the PSM animals (gain = 0.4 cm/vertebra in 6.5 weeks), and grows from 2.6 to 3.1 cm during the period corresponding to the correction of the scoliosis (gain = 0.5 cm/vertebra in 20 weeks).…”

A practical laboratory study simulating the percutaneous lumbar transforaminal epidural injection: training model in fresh cadaveric sheep spine

“…The lower transition to a decreasing pedicle height, which occurs at T11-T12 in the human spine, does not occur until L5 in the sheep spine. Thus, the differences again become exaggerated in the lumbar spine, with pedicle and vertebra height actually being more closely correlated in the sheep than in the human spine (16,18). The spinal canal width are nearly identical, although they differ in value, again mostly toward the extremes.…”

“…Another difference is the curvature in the lumbar spine, which for the sheep is slightly kyphotic rather than lordotic (16). The lower transition to a decreasing pedicle height, which occurs at T11-T12 in the human spine, does not occur until L5 in the sheep spine.…”

Effects of cement augmentation on the mechanical stability of multilevel spine after vertebral compression fracture

“…Cement was also prone to anterior leakage out of the fracture site. As such, the volume injected was not recorded, but it was noted to be considerably less than the average 7 mL used in humans (46), which was expected as sheep have smaller vertebral bodies (47). Moreover, augmentation only achieved fracture repair; possible disc injury and other soft tissue injury were not treated or assessed, apart from measurements taken of the intervertebral disc height.…”