Anatomical variation in intracortical canal network microarchitecture and its influence on bone fracture risk

Piyush Uniyal; Praveer Sihota; Kulbhushan Tikoo; Navin Kumar

doi:10.1016/j.jmbbm.2021.104770

Anatomical variation in intracortical canal network microarchitecture and its influence on bone fracture risk

J Mech Behav Biomed Mater. 2021 Nov:123:104770. doi: 10.1016/j.jmbbm.2021.104770. Epub 2021 Aug 10.

Authors

Piyush Uniyal¹, Praveer Sihota², Kulbhushan Tikoo³, Navin Kumar⁴

Affiliations

¹ Department for Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar, India.
² Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, India.
³ Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, Mohali, India.
⁴ Department for Biomedical Engineering, Indian Institute of Technology Ropar, Rupnagar, India; Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, India. Electronic address: nkumar@iitrpr.ac.in.

PMID: 34392038
DOI: 10.1016/j.jmbbm.2021.104770

Abstract

Intracortical canals are a major contributor to cortical bone porosity and influence its mechanical response. Canal networks act as stress concentrators and the magnitude of which depends on the size and spatial distribution of canals. In the present study, we investigated site-dependent variation in intracortical canal network morphological indices and their effect on the mechanical response of bone. For this, mid-diaphysis of rat tibia bones were scanned using high-resolution micro-CT and morphological indices were measured for four main anatomical sites-anterior, posterior, medial and lateral. Further, a micro-finite element (μFE) model was developed to quantify the stress concentration regions in different cortices. The fracture risk was assessed using an effective strain approach. Results show that canal porosity, canal orientation and canal length are site-dependent whereas canal diameter and canal number density are independent of the site. The lateral cortex has significantly higher porosity compared to the posterior cortex (p < 0.05). The orientation of canals is found significantly different between endosteal and periosteal regions for anterior and medial quadrants. Canals are inclined at higher angles with bone axis in the endosteal region as compare to the periosteal region. The μ-FE results show that the regions with higher effective strain are concentrated around the canals. Further, failed element volume per unit bone volume is found highest for medial cortex whereas lowest for posterior cortex. The higher failed volume is associated with more radial canals in the medial cortex as compare to other cortices. The linear regression analysis shows that the volume of overstrained elements strongly depends on canal orientation (R² = 0.73, p < 0.0001) and canal porosity (R² = 0.61, p < 0.0001). The findings from this study suggest that along with vascular canal porosity, canal orientation and canal diameter can further improve the bone fracture risk assessment.

Keywords: Cortical bone; Cortical porosity; Micro-CT; Micro-FE; Vascular canals.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Bone and Bones
Cortical Bone* / diagnostic imaging
Diaphyses
Fractures, Bone*
Porosity
Rats
Tibia / diagnostic imaging