Anatomy of the sheep spine and its comparison to the human spine

Wilke, Hans–Joachim; Kettler, Annette; Wenger, Karl; Claes, L.

doi:10.1002/(sici)1097-0185(199704)247:4<542::aid-ar13>3.0.co;2-p

Cited by 334 publications

(273 citation statements)

References 31 publications

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“…Our VCW values are also similar, increasing $17% caudally from C3 to C7. Our results do not correspond as well to those measured from sheep (Wilke et al, 1997) in which vertebral canal depth has been reported to increase (by 17%) from C3 to C7. It is unclear whether these relate to functional differences between species, or are the result of different measurement protocols [microCT in the current study vs. a handheld micrometer in Wilke et al (1997)].…”

Section: Discussioncontrasting

confidence: 99%

Effects of Advanced Age on the Morphometry and Degenerative State of the Cervical Spine in a Rat Model

Laing

Cox

Tetzlaff

et al. 2011

The Anatomical Record

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Aging causes changes in the geometry of the human cervical spine that may influence the tissue response to applied loads. Rat models are often used to study spinal cord injuries (SCI) and have the potential to enhance our understanding of the effect of age on SCI. The goal of this study was to characterize the morphometry and degenerative state of the cervical spine in Fisher 344 rats, and to determine the influence of age on these variables. Fifteen rats were split into three age groups: young adult (3 months of age), aged (12-18 months) and geriatric (30 months). Following tissue harvest we used a lCT scanner to image the cervical and upper thoracic spine from each specimen. Analysis software was used to measure variables including canal pinch diameter (the most rostral point on the dorsal aspect of a vertebral body to the most caudal aspect of the lamina on the immediately rostral vertebra), vertebral canal depth, width, and area, vertebral body height, depth, width, and area, and intervertebral disc thickness. Orthopaedic surgeons used midsagittal images to rate the degenerative state of the intervertebral discs. For all measures except disc thickness there was a significant increase (mean (SD) ¼ 15.0 (9.7)%) for the aged compared to young specimens (P < 0.05). There were significant differences between the aged and geriatric specimens for only vertebral body depth (P ¼ 0.016) and area (P ¼ 0.020). Intervertebral disc degeneration was significantly greater on the ventral aspect of the spinal column (P < 0.001), with a trend toward increased degeneration in the geriatric specimens (P ¼ 0.069). The results suggest that agerelated morphometric differences may need to be accounted for in experimental aging models of SCI in rats. Anat Rec, 294:1326Rec, 294: -1336Rec, 294: , 2011. V V C 2011 Wiley-Liss, Inc.

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Section: Discussioncontrasting

confidence: 99%

Effects of Advanced Age on the Morphometry and Degenerative State of the Cervical Spine in a Rat Model

Laing

Cox

Tetzlaff

et al. 2011

The Anatomical Record

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“…It must be emphasized, however, that this opinion is not substantiated in the literature: neither experimental nor theoretical studies were found that show a fundamental difference between the mechanical loading of quadruped and biped spines. On the contrary, several studies show striking similarities in geometry [8,18,43], indicating that quadruped and biped spines must be loaded in a similar way. This idea is further substantiated by studies in which the mechanical properties of spinal segments of sheep, calf and humans have been shown to be comparable [41,42].…”

Section: Theo H Smitmentioning

confidence: 99%

“…This is due to the position of the facet joints, which are oriented at an angle between the sagittal and frontal planes [8,40]. In the thoracic segments, however, the facet joints are more or less aligned in the frontal plane, which leads to a much lower stiffness (1.0-2.1 Nm/ degree), allowing larger rotations [40,43]. Again, muscular forces or ligaments are required to prevent major distortions of the upper trunk.…”

Section: Spinal Loads In a Walking And Running Quadrupedmentioning

confidence: 99%

The use of a quadruped as an in vivo model for the study of the spine – biomechanical considerations

2002

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“…Comparative studies showed that the motion characteristics of the intact spines of calf and sheep are surprisingly similar to those of the human [20,22]. Also, qualitatively, the anatomy of the lumbar spine of these species is similar, yet the sizes partially differ considerably [5,21]. Even based on such comparative data, it is difficult to predict whether a certain species is suitable to test a certain implant because a complex combination of various morphological and functional parameters needs to be considered.…”

Section: Introductionmentioning

confidence: 99%

Are the spines of calf, pig and sheep suitable models for pre-clinical implant tests?

et al. 2007

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Pre-clinical in vitro tests are needed to evaluate the biomechanical performance of new spinal implants. For such experiments large animal models are frequently used. Whether these models allow any conclusions concerning the implant's performance in humans is difficult to answer. The aim of the present study was to investigate whether calf, pig or sheep spine specimens may be used to replace human specimens in in vitro flexibility and cyclic loading tests with two different implant types. First, a dynamic and a rigid fixator were tested using six human, six calf, six pig and six sheep thoracolumbar spine specimens. Standard flexibility tests were carried out in a spine tester in flexion/ extension, lateral bending and axial rotation in the intact state, after nucleotomy and after implantation. Then, the Coflex interspinous implant was tested for flexibility and intradiscal pressure using another six human and six calf lumbar spine segments. Loading was carried out as described above in the intact condition, after creation of a defect and after implantation. The fixators were most easily implantable into the calf. Qualitatively, they had similar effects on ROM in all species, however, the degree of stability achieved differed. Especially in axial rotation, the ROM of sheep, pig and calf was partially less than half the human ROM. Similarly, implantation of the Coflex interspinous implant caused the ROM to either increase in both species or to decrease in both of them, however, quantitatively, differences were observed. This was also the case for the intradiscal pressure. In conclusion, animal species, especially the calf, may be used to get a first idea of how a new pedicle screw system or an interspinous implant behaves in in vitro flexibility tests. However, the effects on ROM and intradiscal pressure have to be expected to differ in magnitude between animal and human. Therefore, the last step in pre-clinical implant testing should always be an experiment with human specimens.

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Anatomy of the sheep spine and its comparison to the human spine

Cited by 334 publications

References 31 publications

Effects of Advanced Age on the Morphometry and Degenerative State of the Cervical Spine in a Rat Model

Effects of Advanced Age on the Morphometry and Degenerative State of the Cervical Spine in a Rat Model

The use of a quadruped as an in vivo model for the study of the spine – biomechanical considerations

Are the spines of calf, pig and sheep suitable models for pre-clinical implant tests?

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