Seminar Series - 1998-1999

A Continuum Mixture Theory with Internal Constraints for Annulus Fibrosus

Stephen M. Klisch
Ph.D. Candidate
Department of Mechanical Engineering, University of California at Berkeley
and Department of Orthopaedic Surgery, University of California at San Francisco
 
Sponsored by: The Department of Engineering Mechanics and the College of Engineering and Technology

Date:  Tuesday, December 8, 1998
Time:  3:30 p.m.
Place:  W128 Nebraska Hall


Intervertebral disc disruption is thought to be a primary cause of low-back pain, and an initiating factor in other instances where a degenerated disc has led to altered spinal mechanics and non-physiologic stresses in surrounding tissues. In an attempt to understand the mechanisms of structural failure and degeneration, a continuum mixture theory with internal constraints is proposed to quantify the mechanical response of the annulus fibrosus of the intervertebral disc. A geometric treatment of internally constrained mixtures of thermoelastic continua at a common temperature will be presented. Constitutive equations for the partial stresses and the diffusive force for an intrinsically incompressible mixture of an elastic solid and an inviscid fluid will be discussed. The determination of material constants representing the solid and fluid elasticities and nonlinear permeability will be discussed using experimental data from a confined compression protocol. Future directions of research will be presented, including the generalization of the proposed continuum mixture theory in order to quantify the growth and remodeling responses of the intervertebral disc.


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