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Agosti, Christopher D. (2006) VISCOELASTIC CHARACTERIZATION OF RABBIT NUCLEUS PULPOSUS TISSUE IN TORSIONAL CREEP. Master's Thesis, University of Pittsburgh. (Unpublished)

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Recently, molecular therapy approaches have been shown to favorably alter the course of intervertebral disc degeneration (IDD) in a rabbit model. Typical experimental outcome measures for the rabbit model of IDD include MRI, x-ray, histology, and gene expression. Biomechanical function is another desirable parameter through which to compare treatments, although this is difficult due to limited availability of data for small animal models. In the current study, nucleus pulposus tissue was taken from the healthy rabbit intervertebral disc and tested in torsional creep to establish a database of healthy tissue behavior for future use in assessing the functional efficacy of molecular therapy treatments of IDD. Nucleus pulposus tissue was excised from the L5-L6 intervertebral disc, mounted between the cone and plate of an AR1000 Rheometer, and various torsional creep experiments were performed. Several creep models were fit to the data and modeling analyses were conducted. Of the models compared, the Andrade creep model provides the most reliable data extrapolation. It appears that the tissue is nonlinearly viscoelastic since it does not adhere to the Boltzmann superposition principle. A nonlinear viscoelastic constitutive model, derived for Andrade creep and used to predict the strain behavior obtained at higher levels of stress, provides consistent prediction results. The application of this model to degenerated rabbit NP tissue is expected to result in altered model parameters - thus providing quantifiable, functional benchmarks of success for molecular therapy approaches to the treatment of IDD.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Agosti, Christopher D.cda9@pitt.eduCDA9
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSmolinski, Patrick J.smolinski@engr.pitt.eduPATSMOL
Committee MemberPlazek, Donald J.
Committee MemberGilbertson, Lars G.
Date: 27 September 2006
Date Type: Completion
Defense Date: 27 April 2006
Approval Date: 27 September 2006
Submission Date: 31 May 2006
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering
Degree: MSME - Master of Science in Mechanical Engineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: creep; degeneration; humidity chamber; hydration; intervertebral disc; mineral oil; nutting; proteoglycan; quasi linear; recovery; rheological; rheology; small animal model; spine; stress relaxation; tissue engineering; yielding; collagen; isochronal; viscoelasticity
Other ID:, etd-05312006-183824
Date Deposited: 10 Nov 2011 19:46
Last Modified: 15 Nov 2016 13:44


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