TY - JOUR
T1 - Growing C57B1/6 mice increase whole bone mechanical properties by increasing geometric and material properties
AU - Brodt, Michael D.
AU - Ellis, Cara B.
AU - Silva, Matthew J.
PY - 1999
Y1 - 1999
N2 - In vivo murine models are becoming increasingly important in bone research. To establish baseline data for researchers using these models, we studied the long bones from C57BL/6 female mice, a strain that is widely used in bone research. We determined the femoral structural and material properties in both torsion and four-point bending for mice at ages 4-24 weeks. Measurements of femoral cross-sectional geometry and tibial densitometric properties were also obtained. Results indicated that all structural properties (except ultimate energy), changed significantly with age (p < 0.001). Ultimate torque, ultimate moment, torsional rigidity, and bending rigidity all increased to peak values at 20 weeks, whereas ultimate rotation and ultimate displacement decreased to minimum values at 20 weeks. Our data indicate that increases in the material properties contributed more than increases in cross-sectional geometry to the changes in structural rigidity and ultimate load. For example, from 4-20 weeks torsional rigidity increased 1030%, while shear modulus increased 610% and the polar moment of inertia (a measure of the geometric resistance to rotation) increased by only 85%. Changes in the cross-sectional geometry with age were due to increases in periosteal diameter and decreases in endosteal diameter. In general, both torsion and bending techniques revealed large changes in structural and material properties with age. We conclude that peak bone strength is not achieved before 20 weeks in C57BL/6 female mice, and that torsion and four- point bending tests are equally well suited for evaluating mechanical properties of murine long bones.
AB - In vivo murine models are becoming increasingly important in bone research. To establish baseline data for researchers using these models, we studied the long bones from C57BL/6 female mice, a strain that is widely used in bone research. We determined the femoral structural and material properties in both torsion and four-point bending for mice at ages 4-24 weeks. Measurements of femoral cross-sectional geometry and tibial densitometric properties were also obtained. Results indicated that all structural properties (except ultimate energy), changed significantly with age (p < 0.001). Ultimate torque, ultimate moment, torsional rigidity, and bending rigidity all increased to peak values at 20 weeks, whereas ultimate rotation and ultimate displacement decreased to minimum values at 20 weeks. Our data indicate that increases in the material properties contributed more than increases in cross-sectional geometry to the changes in structural rigidity and ultimate load. For example, from 4-20 weeks torsional rigidity increased 1030%, while shear modulus increased 610% and the polar moment of inertia (a measure of the geometric resistance to rotation) increased by only 85%. Changes in the cross-sectional geometry with age were due to increases in periosteal diameter and decreases in endosteal diameter. In general, both torsion and bending techniques revealed large changes in structural and material properties with age. We conclude that peak bone strength is not achieved before 20 weeks in C57BL/6 female mice, and that torsion and four- point bending tests are equally well suited for evaluating mechanical properties of murine long bones.
UR - http://www.scopus.com/inward/record.url?scp=0033233166&partnerID=8YFLogxK
U2 - 10.1359/jbmr.1999.14.12.2159
DO - 10.1359/jbmr.1999.14.12.2159
M3 - Article
C2 - 10620076
AN - SCOPUS:0033233166
SN - 0884-0431
VL - 14
SP - 2159
EP - 2166
JO - Journal of Bone and Mineral Research
JF - Journal of Bone and Mineral Research
IS - 12
ER -