Mechanical differences between lumbar and tail discs in the mouse

Sarver, Joseph J.; Elliott, Dawn M.

doi:10.1016/j.orthres.2004.04.010

Cited by 61 publications

(65 citation statements)

References 20 publications

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“…29 Small animal models such as the rat, mouse, and rabbit have been used. 11,31,32,34,[36][37][38] In contrast with humans, these models are smaller and the nucleus pulposus often retains notochordal cells throughout life, possibly affecting its biologic response. 9 Further, these models require a nonnatural perturbation or genetic mutation to induce degeneration.…”

Section: Discussionmentioning

confidence: 99%

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Intervertebral disc degeneration in a naturally occurring primate model: Radiographic and biomechanical evidence

Nuckley

Kramer

Rosario

et al. 2008

Journal Orthopaedic Research

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Classic degenerative disc disease is a serious health problem worldwide, whose etiological basis-mechanical stimulus, biochemical changes, or natural aging-is poorly understood. Animal models are critical to the study of degenerative disc disease initiation and progression and for attempts to regulate, ameliorate, or eliminate it. The macaque represents a primate model with natural disc degeneration that might serve to advance the field; we aimed to provide radiographic (morphologic) and biomechanical evidence of natural disc degeneration in this model. A factorial study design was used to examine the relationship between the radiographic appearance of disc degeneration and its biomechanical consequences. Eighteen macaques of advanced age (22.3 AE 0.9 years) had radiographs taken to assess the degree of thoracolumbar intervertebral disc degeneration using a standard atlas method. Each spine was harvested and dynamic biomechanical tests were performed. Advancing disc degeneration (degree of disc space narrowing and osteophytosis) was associated with increased stiffness, decreased energy absorption, and increased natural frequency of the intervertebral disc. These associations linking the dynamics of the intervertebral disc and its degree of degeneration are similar to those found in humans. Our results indicate the macaque model with morphologic and biomechanical efficacy could aid in understanding the progression of disc degeneration and in developing therapeutic strategies to prevent or inhibit its course. Keywords: intervertebral disc; disc degeneration; Macaca fascicularis; disc dynamics; biomechanics Lumbar intervertebral discs change morphologically, biochemically, and biomechanically with advancing age, 1-10 changes that are characterized as disc degeneration and are implicated as the origin of low back pain. Unfortunately, the initiating and perpetuating factors of disc degeneration are unknown, so despite the pain, disability, and economic loss associated with disc degeneration, intervention and mitigation strategies cannot effectively proceed. Morphologically, dehydration and diminished cellularity of the nucleus pulposus and disorganization and lesions of the annulus fibrosus demarcate disc degeneration. These changes manifest as decreased disc height, increased radial bulging, and osteophyte formation. 11,12 Morphologic changes are intrinsically tied to the biochemistry and biomechanics of the system, and visible and radiographic changes are used to define gradations of disc degeneration. [13][14][15][16] The altered biomechanical response of degenerate disc tissues have been measured. [2][3][4][17][18][19][20][21][22][23][24] Disc stiffness decreases with low-grade degeneration and increases with the most severe degeneration, while energy absorption decreases throughout degeneration. Further, spinal segment range of motion and neutral zone increase with advancing degeneration up to the most severely degenerated discs, where these properties reverse course with increasing stiffness. Unfortun...

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Section: Discussionmentioning

confidence: 99%

“…28,29 Animal models can clarify pathomechanisms and aid in development of therapeutic strategies. While most animal models require mechanical or chemical induction, 4,[29][30][31][32][33][34][35][36][37][38] the macaque has naturally degenerating intervertebral discs (Fig. 1).…”

mentioning

confidence: 99%

Intervertebral disc degeneration in a naturally occurring primate model: Radiographic and biomechanical evidence

Nuckley

Kramer

Rosario

et al. 2008

Journal Orthopaedic Research

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“…Axial compression-tension cyclic testing followed by a compressive creep test was performed as described previously. 27,35,36 Compressiontension testing was selected over solely compression, as in addition to compressive and tensile properties the transitional low-load neutral zone properties are quantified. The vertebral bodies of the motion segment were gripped using customized microvises attached to an Instron 5542 testing system (Instron, Canton, MA).…”

Section: Mechanical Testingmentioning

confidence: 99%

“…Data from the 20th loading cycle of tensioncompression testing was analyzed using the trilinear fit model 27,35,36 to obtain values for compressive, tensile, and neutral zone stiffness, as well as neutral zone displacement and cyclic range of motion. The 20th loading cycle was selected for analysis, as it has been shown that a motion segment is adequately preconditioned by the 20th loading cycle, eliminating the effects of super hydration, which may have resulted from the period of free swelling in PBS during the treatment protocol.…”

Section: Mechanical Testingmentioning

confidence: 99%

Nucleus pulposus glycosaminoglycan content is correlated with axial mechanics in rat lumbar motion segments

et al. 2006

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The unique biochemical composition and structure of the intervertebral disc allow it to support load, permit motion, and dissipate energy. With degeneration, both the biochemical composition and mechanical behavior of the disc are drastically altered, yet quantitative relationships between the biochemical changes and overall motion segment mechanics are lacking. The objective of this study was to determine the contribution of nucleus pulposus glycosaminoglycan content, which decreases with degeneration, to mechanical function of a rat lumbar spine motion segment in axial loading. Motion segments were treated with varying doses of Chondroitinase-ABC (to degrade glycosaminoglycans) and loaded in axial cyclic compression-tension, followed by compressive creep. Nucleus glycosaminoglycan content was significantly correlated ( p < 0.05) with neutral zone mechanical behavior, which occurs in low load transition between tension and compression (stiffness: r ¼ 0.59; displacement: r ¼ À0.59), and with creep behavior (viscous parameter h 1 : r ¼ 0.34; short time constant t 1 : r ¼ 0.46). These results indicate that moderate decreases in nucleus glycosaminoglycan content consistent with early human degeneration affect overall mechanical function of the disc. These decreases may expose the disc to altered internal stress and strain patterns, thus contributing through mechanical or biological mechanisms to the degenerative cascade. ß

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“…rabbits, rats, and mice) (Iatridis et al, 1999;Gruber et al, 2002;Ching et al, 2003;Hsieh and Lotz, 2003;Norcross et al, 2003;Risbud et al, 2003;Maclean et al, 2004;An et al, 2005;Kim et al, 2005;Sobajima et al, 2005). It was recently reported that mouse lumbar discs matched the previously reported nonlinear response of human lumbar discs while mouse caudal discs only matched the linear response provided differences in cross-sectional areas were accounted for (Sarver and Elliott, 2005).…”

Section: Introductionmentioning

confidence: 73%

Role of endplates in contributing to compression behaviors of motion segments and intervertebral discs

MacLean

Owen

Iatridis

2007

Journal of Biomechanics

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The purpose of this study was to gain an improved understanding of the mechanical behavior of the intervertebral disc in the presence and absence of the vertebral endplates. Mechanical behaviors of rat caudal motion segments, vertebrae and isolated disc explants under two different permeability conditions were investigated and viscoelastic behaviors were evaluated using a stretched-exponential function to describe creep and recovery behaviors. The results demonstrated that both vertebrae and discs underwent significant deformations in the motion segment even under relatively low-loading conditions. Secondly, disruption of the collagenous network had minimal impact on equilibrium deformations of disc explants as compared to disc deformations occurring in the motion segments provided that vertebral deformations were accounted for; however, differences in endplate permeability conditions had a significant effect on viscoelastic behaviors. Creep occurred more quickly than recovery for motion segment and explant specimens. In addition, disc explants and motion segments both exhibited non-recoverable deformations under axial compression under lowand high-loading conditions. Results have important implications for interpreting the role of vertebral endplates in contributing to disc mechanical behaviors and direct application to mechanobiology studies involving external loading to rodent tail intervertebral discs.

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Mechanical differences between lumbar and tail discs in the mouse

Cited by 61 publications

References 20 publications

Intervertebral disc degeneration in a naturally occurring primate model: Radiographic and biomechanical evidence

Intervertebral disc degeneration in a naturally occurring primate model: Radiographic and biomechanical evidence

Nucleus pulposus glycosaminoglycan content is correlated with axial mechanics in rat lumbar motion segments

Role of endplates in contributing to compression behaviors of motion segments and intervertebral discs

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