Modeling of Bone Lacunar-Canalicular Network

Purposes

Develop modeling tools for converting measurement data to numerical models of bone microstructures (osteocyte lacunae, canaliculi, osteons, Haversian canals).
Evaluating the influence of structural alterations in bone microstructures on the local and tissue-level mechanical properties (volumetric deformation, elastic modulus, ultimate strength, fracture energy, etc.) using finite element analysis.
Gain insight into the roles of bone microstructures on mechanosensing and mechanotransducing.

A planar model of bone tissue with osteocyte lacunae represented as elliptical pores.
Crack initiation and propagation are simulated with interface cohesive elements are inserted among solid elements
The geometry information (axis length, orientation, and location) of osteocyte lacunae was acquired from experimental measurements and converted to computational models using MATLAB scripts

A 3D model (Left) of bone tissue with multiple osteocyte lacunae represented using ellipsoidal voids with adjustable size, shape and orientation.
Perilacunar regions are represented using ellipsoidal regions with adjustable thickness and elastic modulus around lacunae.
The geometry information (axis length, equancy, elongation, flatness, and orientation) of osteocyte lacunae was acquired from experimental measurements and converted to computational models using MATLAB scripts

A 3D model containing multiple osteocyte lacunae with canalicular dendrites.
Canalicular dendrites are represented using cylindrical rods normal to the lacuanr surface.
The pin part
The geometry information of osteocyte lacunae (axis length, equancy, orientation, and location) and canaliculi (length, density and diameter) was acquired from experimental measurements and converted to computational models using MATLAB scripts

The 3D FEA model above showed stress concentration sites on surface of a single osteocyte lacuna with canalicular dendrites. Note the stress conentration near the roots of canaliculi

The 2D FEA model above showed stress concentration sites on the ends of lacunar axes perpendicular to the loading direction, no matter how the major axes of lacunae aligned

The cracks initiated around stress concentration sites and lateral edges of the FEA model.
The difference was that crack initiation sites only occurred near lacunar major axes.
The propagation of the crack was guided by multiple osteocyte lacunae, which indicated osteocyte lacunae can deflect the propagation of microcracks.

Strain amplification foctor

The strain amplification factor is the ratio of them maximum principal strain to total applied strain, which indicates the ability of lacunar mechanotransducing.
We found that the strain amplication factor is linearly corresponded to lacunar orientation and perilacular modulus. It is also exponentially corresponded to lacunar volume. This indicates that the strain amplification is larger around larger lacunae, which align perpendicularly to the loading direction and are surrounded by softened perilacuar tissue
There was no significant relationships between the stain amplification factor and canalicular parameters

Crack initiation and propagation in a 3D model

Damaged elements in a 3D model

The crack propagation became much more linear (left) after inserting mineralized lacunae into the FEA model (right)
This validates the guiding effect of osteocyte lacunae on the crack formation and the downside influnce of mineralized lacuane on the crack propagation.

ASBMR2020_eposter_wsang.pptx

ASBMR2022_eposter_Sang_final.pptx

Sang, Wen, and Ani Ural. "Influence of Osteocyte Lacunar-Canalicular Morphology and Network Architecture on Osteocyte Mechanosensitivity." Current Osteoporosis Reports (2023): 1-13. https://link.springer.com/article/10.1007/s11914-023-00792-9
Sang, Wen, and Ani Ural. "Evaluating the Role of Canalicular Morphology and Perilacunar Region Properties on Local Mechanical Environment of Lacunar–Canalicular Network Using Finite Element Modeling." Journal of Biomechanical Engineering 145, no. 6 (2023): 061006. https://doi.org/10.1115/1.4056655
Sang, Wen. "Evaluating the Role of Lacunar-Canalicular Network on Bone Mechanical Properties Using Computational Modeling." PhD diss., Villanova University, 2023. https://www.proquest.com/openview/746a3bade208c9a390bff45328b5afe6/1?pq-origsite=gscholar&cbl=18750&diss=y
Sang, Wen, and Ani Ural. "Quantifying how altered lacunar morphology and perilacunar tissue properties influence local mechanical environment of osteocyte lacunae using finite element modeling." Journal of the Mechanical Behavior of Biomedical Materials 135 (2022): 105433. https://doi.org/10.1016/j.jmbbm.2022.105433
Sang, Wen, Yihan Li, Jane Guignon, X. Sherry Liu, and Ani Ural. "Structural role of osteocyte lacunae on mechanical properties of bone matrix: A cohesive finite element study." Journal of the Mechanical Behavior of Biomedical Materials 125 (2022): 104943. https://doi.org/10.1016/j.jmbbm.2021.104943

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