Load-displacement properties of the thoracolumbar calf spine: Experimental results and comparison to known human data

Wilke, Hans–Joachim; Krischak, Stefan; Wenger, Karl; Claes, Lutz

doi:10.1007/bf01358746

Cited by 92 publications

(86 citation statements)

References 62 publications

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“…This observation probably also applies for the segments L2-3, L3-4 and L4-5 since these levels have the same main anatomical characteristics. Also, the three-dimensional flexibility is known to be very similar for all these levels [20,22]. Therefore, if any of the segments L2-3, L3-4 or L4-5 would have been tested instead of L1-2, very similar differences and similarities between either of the three animals and the human would have been expected.…”

Section: Discussionmentioning

confidence: 99%

“…Whether these models allow any conclusions concerning the implant's performance in humans is difficult to answer. 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].…”

Section: Introductionmentioning

confidence: 89%

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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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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 89%

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

et al. 2007

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“…It was found that lumbar calf discs may serve as model for this kind of experiments because the size and shape and structure of the disc is similar to the human lumbar disc [25]. Previous biomechanical investigations showed also similarities regarding spinal flexibility [25].…”

Section: Discussionmentioning

confidence: 99%

Is a collagen scaffold for a tissue engineered nucleus replacement capable of restoring disc height and stability in an animal model?

et al. 2006

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The idea of a tissue engineered nucleus implant is to seed cells in a three-dimensional collagen matrix. This matrix may serve as a scaffold for a tissue engineered nucleus implant. The aim of this study was to investigate whether implantation of the collagen matrix into a spinal segment after nucleotomy is able to restore disc height and flexibility. The implant basically consists of condensed collagen type-I matrix. For clinical use, this matrix will be used for reinforcing and supporting the culturing of nucleus cells. In experiments, matrixes were concentrated with barium sulfate for X-ray purposes and cell seeding was disclaimed in order to evaluate the biomechanical performance of the collagen material. Six bovine lumbar functional spinal units, aging between 5 and 6 months, were used for the biomechanical in-vitro test. In each specimen, an oblique incision was performed, the nucleus was removed and replaced by a collagen-type-I matrix. Specimens were mounted in a custom-built spine tester, and subsequently exposed to pure moments of 7.5 Nm to move within the three anatomical planes. Each tested stage (intact, nucleotomy and implanted) was evaluated for range of motion, neutral zone and change in disc height. Removal of the nucleus significantly reduced disc height by 0.84 mm in respect to the intact stage and caused an instability in the segment. Through the implantation of the tissue engineered nucleus it was possible to restore this height and stability loss, and even to increase slightly the disc height of 0.07 mm compared with the intact stage. There was no statistical difference between the stability provided by the implant and intact stage. Results of movements in lateral bending and axial rotation showed the same trend compared to flexion/extension. However, implant extrusions have been observed in three of six cases during the flexibility assessment. The results of this study directly reflect the efficacy of vital nucleus replacement to restore disc height and to provide stability to intervertebral discs. However, from a biomechanical point of view, the challenge is to employ an appropriate annulus fibrosus sealing method, which is capable to keep the nucleus implant in place over a long-time period. Securing the nucleus implant inside the disc is one of the most important biomechanical prerequisites if such a tissue engineered implant shall have a chance for clinical application.

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“…Optimal in vivo testing should use a mature mammal with lumbar disc morphology and in vivo loading that approximate those of the human spine. Domestic mammal spines have often been used for in vitro testing of lumbar spinal fusion implants because motion segment load-displacement relationships are somewhat similar to human data [4][5][6][7][8][9]. But most of these animals, such as the dog, sheep, goat and pig, have vertebra and disc anatomy which are substantially smaller than that of humans [10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Mature runt cow lumbar intradiscal pressures and motion segment biomechanics

2009

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Background Context-The optimal animal model for in vivo testing of spinal implants, particularly total or partial disc replacement devices, has not yet been determined. Mechanical and morphological similarities of calf and human spines have been reported; however, limitations of the calf model include open growth plates and oversized vertebrae with growth. Mature runt cows (Corrientes breed) may avoid these limitations.

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Load-displacement properties of the thoracolumbar calf spine: Experimental results and comparison to known human data

Cited by 92 publications

References 62 publications

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

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

Is a collagen scaffold for a tissue engineered nucleus replacement capable of restoring disc height and stability in an animal model?

Mature runt cow lumbar intradiscal pressures and motion segment biomechanics

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