Researcher(s)
- Ethan Stoecker, Biomedical Engineering, University of Delaware
Faculty Mentor(s)
- Stephanie Cone, Biomedical Engineering, University of Delaware
Abstract
Osteoarthritis (OA) is characterized as a degenerative disease that affects entire joint function and structure [1]. To better understand the effects of OA on skeletal structure, mouse models are frequently employed due to the wide availability of surgical and genetic tools available for inducing OA. High resolution 3D imaging (micro-CT and MRI) along with uni- and multi-axial mechanical testing are commonly used to study structure-function relationships and the effects of OA [2]. The goal of this study was to conduct strength and structural testing using healthy long bones to allow for baseline expectations to be formed about long bone structure-function. This will facilitate further pathological research into the effects of OA. It was hypothesized that femora would show greater strength than tibiae, and that femoral bone structural measurements would be larger.
Ten healthy mouse femora and tibiae were dissected, and all soft tissue was removed. Micro CT scanning, analysis, and three-point bend testing were performed [2]. Using custom MATLAB code, force-displacement curves, stiffness, yield point, fracture point, post-yield displacement (PYD), and work-to-fracture (WTF) were calculated [3].
Femora had higher averages than tibiae ranging from 38% – 74% in stiffness, yield point, fracture point, PYD, and WTF. Femora also showed higher measurements in bone volume fraction and total cross-sectional area by 40% and 43%, respectively. Finally, femora showed much higher averages in minimum and maximum moment of inertia, with increases of 133% and 183%, respectively. Trabecular and cortical thickness, along with bone surface volume fraction showed no differences between femora and tibiae.
Femora had stronger mechanical properties than tibiae, and a similar trend followed with structural properties, where larger cortical and trabecular sizes were observed in femora. This suggests that structural properties of long bones play an imperative role in how long bones respond to biomechanical interactions.