Structural and Mechanical Improvements to Bone Are Strain Dependent with Axial Compression of the Tibia in Female C57BL/6 Mice

Alycia G Berman; Creasy A Clauser; Caitlin Wunderlin; Max A Hammond; Joseph M Wallace

doi:10.1371/journal.pone.0130504

Structural and Mechanical Improvements to Bone Are Strain Dependent with Axial Compression of the Tibia in Female C57BL/6 Mice

PLoS One. 2015 Jun 26;10(6):e0130504. doi: 10.1371/journal.pone.0130504. eCollection 2015.

Authors

Alycia G Berman¹, Creasy A Clauser¹, Caitlin Wunderlin¹, Max A Hammond², Joseph M Wallace³

Affiliations

¹ Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, United States of America.
² Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States of America.
³ Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, United States of America; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States of America; Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN, United States of America.

Abstract

Strain-induced adaption of bone has been well-studied in an axial loading model of the mouse tibia. However, most outcomes of these studies are restricted to changes in bone architecture and do not explore the mechanical implications of those changes. Herein, we studied both the mechanical and morphological adaptions of bone to three strain levels using a targeted tibial loading mouse model. We hypothesized that loading would increase bone architecture and improve cortical mechanical properties in a dose-dependent fashion. The right tibiae of female C57BL/6 mice (8 week old) were compressively loaded for 2 weeks to a maximum compressive force of 8.8N, 10.6N, or 12.4N (generating periosteal strains on the anteromedial region of the mid-diaphysis of 1700 με, 2050 με, or 2400 με as determined by a strain calibration), while the left limb served as an non-loaded control. Following loading, ex vivo analyses of bone architecture and cortical mechanical integrity were assessed by micro-computed tomography and 4-point bending. Results indicated that loading improved bone architecture in a dose-dependent manner and improved mechanical outcomes at 2050 με. Loading to 2050 με resulted in a strong and compelling formation response in both cortical and cancellous regions. In addition, both structural and tissue level strength and energy dissipation were positively impacted in the diaphysis. Loading to the highest strain level also resulted in rapid and robust formation of bone in both cortical and cancellous regions. However, these improvements came at the cost of a woven bone response in half of the animals. Loading to the lowest strain level had little effect on bone architecture and failed to impact structural- or tissue-level mechanical properties. Potential systemic effects were identified for trabecular bone volume fraction, and in the pre-yield region of the force-displacement and stress-strain curves. Future studies will focus on a moderate load level which was largely beneficial in terms of cortical/cancellous structure and cortical mechanical function.

Publication types

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

MeSH terms

Animals
Female
Mice
Mice, Inbred C57BL
Stress, Mechanical*
Tibia / physiology*
Weight-Bearing / physiology

Grants and funding

This work was supported by IUPUI (Indiana University-Purdue University at Indianapolis) departmental start-up funds, Research Support Funds Grant from the IUPUI Office of the Vice Chancellor for Research and funding from the IUPUI Biomechanics and Biomaterials Research Center.