Human annulus fibrosus dynamic tensile modulus increases with degeneration

Sen, Sounok; Jacobs, Nathan T.; Boxberger, John I.; Elliott, Dawn M.

doi:10.1016/j.mechmat.2011.07.016

Cited by 20 publications

(12 citation statements)

References 24 publications

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“…Measuring the biphasic-swelling properties of the individual disc tissues is important as benchmarks for tissue engineering and for modeling the disc's mechanical behavior and transport. The tensile mechanical behavior of the fiber-reinforced AF has been extensively studied and accurately described using constitutive models (Guerin and Elliott, 2007; Guo et al, 2012; Klisch and Lotz, 1999; O'Connell et al, 2012; Sen et al, 2012; Wagner and Lotz, 2004; Wagner et al, 2006; Wu and Yao, 1976). However, mechanical properties of the human AF extra-fibrillar matrix have been less explored, and the reported values for permeability span several orders of magnitude (Table 1).…”

Section: Introductionmentioning

confidence: 99%

Elastic, permeability and swelling properties of human intervertebral disc tissues: A benchmark for tissue engineering

Cortés

Jacobs

DeLucca

et al. 2014

Journal of Biomechanics

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SUMMARY The aim of functional tissue engineering is to repair and replace tissues that have a biomechanical function, i.e., connective orthopaedic tissues. To do this, it is necessary to have accurate benchmarks for the elastic, permeability, and swelling (i.e., biphasic-swelling) properties of native tissues. However, in the case of the intervertebral disc, the biphasic-swelling properties of individual tissues reported in the literature exhibit great variation and even span several orders of magnitude. This variation is probably caused by differences in the testing protocols and the constitutive models used to analyze the data. Therefore, the objective of this study was to measure the human lumbar disc annulus fibrosus (AF), nucleus pulposus (NP), and cartilaginous endplates (CEP) biphasic-swelling properties using a consistent experimental protocol and analyses. The testing protocol was composed of a swelling period followed by multiple confined compression ramps. To analyze the confined compression data, the tissues were modeled using a biphasic-swelling model, which augments the standard biphasic model through the addition of a deformation-dependent osmotic pressure term. This model allows considering the swelling deformations and the contribution of osmotic pressure in the analysis of the experimental data. The swelling stretch was not different between the disc regions (AF: 1.28±0.16; NP: 1.73±0.74; CEP: 1.29±0.26), with a total average of 1.42. The aggregate modulus (Ha) of the matrix was higher in the CEP (390 kPa) compared to the NP (100 kPA) or AF (30 kPa). The permeability was very different across tissues regions, with the AF permeability (80 E−4 mm4/Ns) higher than the NP and CEP (6-7 E−16 m4/Ns). Additionally, a normalized time-constant (3000 sec) for the stress relaxation was similar for all the disc tissues. The properties measured in this study are important as benchmarks for tissue engineering and for modeling the disc's mechanical behavior and transport.

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Section: Introductionmentioning

confidence: 99%

Elastic, permeability and swelling properties of human intervertebral disc tissues: A benchmark for tissue engineering

Cortés

Jacobs

DeLucca

et al. 2014

Journal of Biomechanics

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“…51 Compression stiffness in healthy human spinal motion segment linearly increases as frequency increases in log scale. 51,52 Such frequency dependence of disc stiffness has been demonstrated in human discs 53,54 and pig discs. 55 This may be related to the stiffening effect and the fluid flow effect, which refers to more transport of fluid and ions and higher GAGs in central NP at high frequency as the disc is compressed.…”

Section: Msc-collagen Microsphere Group Showed Better Dynamic Mechanimentioning

confidence: 81%

Delivering Mesenchymal Stem Cells in Collagen Microsphere Carriers to Rabbit Degenerative Disc: Reduced Risk of Osteophyte Formation

Diao

Chik

et al. 2014

Tissue Engineering Part A

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Mesenchymal stem cells (MSCs) have the potential to treat early intervertebral disc (IVD) degeneration. However, during intradiscal injection, the vast majority of cells leaked out even in the presence of hydrogel carrier. Recent evidence suggests that annulus puncture is associated with cell leakage and contributes to osteophyte formation, an undesirable side effect. This suggests the significance of developing appropriate carriers for intradiscal delivery of MSCs. We previously developed a collagen microencapsulation platform, which entraps MSCs in a solid microsphere consisting of collagen nanofiber meshwork. These solid yet porous microspheres support MSC attachment, survival, proliferation, migration, differentiation, and matrix remodeling. Here we hypothesize that intradiscal injection of MSCs in collagen microspheres will outperform that of MSCs in saline in terms of better functional outcomes and reduced side effects. Specifically, we induced disc degeneration in rabbits and then intradiscally injected autologous MSCs, either packaged within collagen microspheres or directly suspended in saline, into different disc levels. Functional outcomes including hydration index and disc height were monitored regularly until 6 months. Upon sacrifice, the involved discs were harvested for histological, biochemical, and biomechanical evaluations. MSCs in collagen microspheres showed advantage over MSCs in saline in better maintaining the dynamic mechanical behavior but similar performance in hydration and disc height maintenance and matrix composition. More importantly, upon examination of gross appearance, radiograph, and histology of IVD, delivering MSCs in collagen microspheres significantly reduced the risk of osteophyte formation as compared to that in saline. This work demonstrates the significance of using cell carriers during intradiscal injection of MSCs in treating disc degeneration.

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“…They allow motion, permitting spinal flexibility, and distribute shock across the spinal column. [6] The nucleus pulposus, the gel-like centric section of the disc, is usually hydrated. It consists of water in a matrix of proteoglycans, collagen, and other proteins.…”

Section: Discussionmentioning

confidence: 99%

Traumatic lumbar disc herniation mimicking epidural hematoma

Kim

Lee

et al. 2019

Medicine

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Rationale: We report a rare case of traumatic lumbar disc herniation mimicking epidural hematoma. Patient concerns: A 39-year old man presented with acute bilateral leg and back pain, following a crushing injury caused by a crane collapse. Diagnosis: A computed tomography scan revealed multiple compression fractures of the thoracolumbar spine, including a burst fracture of the L4 vertebral body. Magnetic resonance imaging (MRI) showed an epidural mass, extending longitudinally and causing dural sac compression behind the L3 vertebra. The mass had isosignal intensity on T1-weighted imaging and showed mixed high and low signals on T2-weighted imaging. On the basis of the patient's clinical history and imaging findings, our provisional diagnosis was an epidural hematoma following major trauma. Interventions: An emergency L3 laminectomy was performed with percutaneous screw fixation of L3-5. Intraoperatively, 3 large herniated disc fragments were found at L3 with no evidence of hematoma. Outcomes: The patient recovered normal motor function after surgery. At the last follow-up, 3 years after surgery, there was no residual neurological deficit apart from intermittent lower back pain. Lessons: In cases where MRI findings reveal an epidural lesion with a longitudinal shape, similar to an epidural hematoma, with mixed signal intensity on T2-weighted images and high peripheral signal intensity on T1-weighted images, traumatic disc herniation should be included in the differential diagnosis.

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Human annulus fibrosus dynamic tensile modulus increases with degeneration

Cited by 20 publications

References 24 publications

Elastic, permeability and swelling properties of human intervertebral disc tissues: A benchmark for tissue engineering

Elastic, permeability and swelling properties of human intervertebral disc tissues: A benchmark for tissue engineering

Delivering Mesenchymal Stem Cells in Collagen Microsphere Carriers to Rabbit Degenerative Disc: Reduced Risk of Osteophyte Formation

Traumatic lumbar disc herniation mimicking epidural hematoma

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