An experimental validation and analytical model of the hydraulic stiffening of cancellous bone
Abstract
The study of bone mechanics, especially cancellous bone, has historically ignored the mechanical and physiologic roles of the fluid component of the tissue. This study presents a systematic effort to corroborate the existence of a hydraulic stiffening phenomenon within the bones of synovial joints ex vivo and in vivo. The experimentally verified hydraulic stiffening phenomenon is then effectively modeled by analyzing the macroscopic, structural behavior of bone phenomenologically, and choosing an appropriate analytical model (Biot's Theory of Poroelasticity). The permeability of cancellous bone and bulk modulus of bone marrow were determined experimentally. The results of poroelastic finite element simulations of bone plugs and whole fermoral heads compared favorably with experimental results to demonstrate the applicability of Biot's theory to the study of cancellous bone mechanics. The effective mechanical properties of the solid-fluid composite are approximated by two methods: from a typical continuum finite element model, and from a representative microstructural cancellous unit cell, including the fluid. Finally, the repercussions of the accurate characterization of the effective tissue stress and pore pressure on the modeling of orthopaedic systems, bone micro fatigue and failure, and the idea of hydrostatic pressure as the foundation of a mechanosensory system in bone which triggers remodeling are discussed.
Degree
Ph.D.
Advisors
Hillberry, Purdue University.
Subject Area
Mechanical engineering|Biomedical research
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