title: Predicting the permeability of trabecular bone by micro-computed tomography and finite element modeling.
abstract: The intrinsic permeability of bone plays an important role in the transport of nutrients and minerals within the tissue, and affects the mechanical stimuli that are related to the fate of the stem cells. The objective of this study was to establish a method to assess trabecular bone permeability using experimental and finite element (FE) modeling approaches based on micro computed tomography (µCT) images. Human cadaveric tibia cube specimens (N=23) were scanned with µCT. The permeability was measured experimentally using a custom-developed constant-head permeameter, and computationally by a poroelastic formulation to simulate the fluid flow within the discretized bone matrix and pore phase. The average of the experimentally measured permeability was 4.84 × 10(-10)m(2) with a standard deviation of 3.70 × 10(-10)m(2). A regression model of the µCT determined that the maximum bone area to total area ratio (maxBA/TA) for all slices that are perpendicular to the direction of fluid flow explained 84% of the variability of the natural logarithm of the experimentally measured permeability. The 2D measure of maxBA/TA performed better than 3D measures in general, although some parameters were reasonably well associated with permeability such as bone volume ratio (BV/TV, r=-0.71), the bone surface/bone volume (BS/BV, r=0.73), and the trabecular thickness (TbTh, r=-0.71). The correlation between the permeability predicted with FE models and experimentally measured permeability was reasonable (r=0.69), but the FE approach did not accurately represent the wide variability of permeability measured experimentally. The results of this study suggest that the changes in the trabecular bone microarchitecture have an exponential relationship with permeability, and the use of µCT-based 2D measurement of maxBA/TA performs well at predicting permeability, thus providing a convenient approach to measure this important aspect affecting biomechanical functions in the tissue.
authors.affiliation: McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada T2N 4Z6; Schulich School of Engineering, University of Calgary, Calgary, AB, Canada; Roger Jackson Centre for Health and Wellness Research, University of Calgary, Calgary, AB, Canada.
authors.forename: Clara
authors.initials: C
authors.lastname: Sandino
authors.affiliation: McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada T2N 4Z6; Schulich School of Engineering, University of Calgary, Calgary, AB, Canada; Roger Jackson Centre for Health and Wellness Research, University of Calgary, Calgary, AB, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Kroliczek
authors.affiliation: McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada T2N 4Z6; Schulich School of Engineering, University of Calgary, Calgary, AB, Canada; Roger Jackson Centre for Health and Wellness Research, University of Calgary, Calgary, AB, Canada.
authors.forename: David D
authors.initials: DD
authors.lastname: McErlain
authors.affiliation: McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, AB, Canada T2N 4Z6; Schulich School of Engineering, University of Calgary, Calgary, AB, Canada; Roger Jackson Centre for Health and Wellness Research, University of Calgary, Calgary, AB, Canada; Department of Radiology, Faculty of Medicine, University of Calgary, Calgary, AB, Canada. Electronic address: skboyd@ucalgary.ca.
authors.forename: Steven K
authors.initials: SK
authors.lastname: Boyd
mesh_terms: D020342:Finite Element Analysis; D006801:Humans; D008954:Models, Biological; D010539:Permeability; D013977:Tibia / Q000000981:diagnostic imaging* / Q000378:metabolism*; D055114:X-Ray Microtomography
keywords: Finite element models; Micro computed tomography; Permeability; Trabecular bone