Replacing the nucleus pulposus of the intervertebral disc

Meakin, Judith R.; Reid, Janet Elizabeth; Hukins, D. W. L.

doi:10.1016/s0268-0033(01)00042-0

Cited by 67 publications

(46 citation statements)

References 15 publications

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“…Both the present study and previous investigations 14,15 suggest that there are four main mechanical characteristics in a nucleus replacement device that could dictate, along with their interplay, if these functions can be satisfi ed: (1) the ability to conform to a nucleus cavity; (2) the material properties such as compression modulus; (3) the ability to permit segmental fl exibility with preservation of disc height; and (4) the ability to minimize or eliminate migration.…”

Section: Nucleus Replacementsupporting

confidence: 87%

“…Inward annular bulging, typically present with degeneration of the nucleus pulposus, 16,17 can lead to annular delamination, which further worsens annular degeneration. Experimental 15 and fi nite element 14 studies have demonstrated that if a nucleus replacement device maintains intimate contact with the surrounding annulus, inward annular bulging can be avoided.…”

Section: Nucleus Replacementmentioning

confidence: 99%

See 1 more Smart Citation

Mechanical and Biomechanical Characterization of a Polyurethane Nucleus Replacement Device Injected and Cured In Situ Within a Balloon

Tsantrizos¹,

Ordway

Myint³

et al. 2008

SAS Journal

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BackgroundTh e DASCOR device has recently been introduced as an innovative nucleus replacement alternative for the treatment of low-back pain caused by degenerative intervertebral disc disease. Th e purpose of this study was to characterize, through a series of preclinical mechanical bench and biomechanical tests, the eff ectiveness of this device. MethodsA number of samples were created using similar preparation methods in order to characterize the nucleus replacement device in multiple mechanical bench tests, using ASTM-guided protocols, where appropriate. Mechanical bench testing included static testing to characterize the device's compressive, shear properties, and fatigue testing to determine the device's compressive fatigue strength, wear, and durability. Biomechanical testing, using human cadaveric lumbar spines, was also conducted to determine the ability of the device to restore multidirectional segmental fl exibility and to determine its resulting endplate contact stress. ResultsTh e static compressive and shear moduli of the nucleus replacement device were determined to be between 4.2-5.6 MPa and 1.4-1.9 MPa, respectively. Similarly, the ultimate compressive and shear strength were 12,400 N and 6,993 N, respectively. Th e maximum axial compressive fatigue strength of the tested device that was able to withstand a runout without failure was determined to be approximately 3 MPa. Th e wear assessment determined that the device is durable and yielded minimal wear rates of 0.29mg/Mc. Finally, the biomechanical testing demonstrated that the device can restore the multidirectional segmental fl exibility to a level seen in the intact condition while concurrently producing a uniform endplate contact stress. ConclusionsTh e results of the present study provided a mechanical justifi cation supporting the clinical use of the nucleus replacement device and also help explain and support the positive clinical results obtained from two European studies and one US pilot study. Clinical RelevanceNucleus replacement devices are rapidly emerging to address specifi c conditions of degenerative disc disease. Preclinical testing of such devices is paramount in order to potentially ensure successful clinical outcomes post implantation

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Section: Nucleus Replacementsupporting

confidence: 87%

Section: Nucleus Replacementmentioning

confidence: 99%

Mechanical and Biomechanical Characterization of a Polyurethane Nucleus Replacement Device Injected and Cured In Situ Within a Balloon

Tsantrizos¹,

Ordway

Myint³

et al. 2008

SAS Journal

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“…In contrast, discectomy benefits good shortterm effects of pain relieve, but it reduces disc height and increases segmental instability. This can lead to more stress in the remaining annulus but also in the facet joints [3,4,14,15], which may lead to an accelerated further degeneration.…”

Section: Introductionmentioning

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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“…The nucleus populous was considered incompressible and was modeled as 3D tetrahedral solid elements [11,14]. The denucleated disc only includes annulus fiber tissue (Fig.…”

Section: Removal Of the Nucleusmentioning

confidence: 99%

An Approach to Lumbar Vertebra Biomechanical Analysis Using the Finite Element Modeling Based on CT Images

Li¹

2011

Theory and Applications of CT Imaging and Analysis

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Replacing the nucleus pulposus of the intervertebral disc

Cited by 67 publications

References 15 publications

Mechanical and Biomechanical Characterization of a Polyurethane Nucleus Replacement Device Injected and Cured In Situ Within a Balloon

Mechanical and Biomechanical Characterization of a Polyurethane Nucleus Replacement Device Injected and Cured In Situ Within a Balloon

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

An Approach to Lumbar Vertebra Biomechanical Analysis Using the Finite Element Modeling Based on CT Images

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