TY - JOUR
T1 - Adaptive enhancement of apatite crystal orientation and Young's modulus under elevated load in rat ulnar cortical bone
AU - Wang, Jun
AU - Ishimoto, Takuya
AU - Matsuzaka, Tadaaki
AU - Matsugaki, Aira
AU - Ozasa, Ryosuke
AU - Matsumoto, Takuya
AU - Hayashi, Mikako
AU - Kim, Hyoung Seop
AU - Nakano, Takayoshi
N1 - Publisher Copyright:
© 2024 The Author(s)
PY - 2024/4
Y1 - 2024/4
N2 - Functional adaptation refers to the active modification of bone structure according to the mechanical loads applied daily to maintain its mechanical integrity and adapt to the environment. Functional adaptation relates to bone mass, bone mineral density (BMD), and bone morphology (e.g., trabecular bone architecture). In this study, we discovered for the first time that another form of bone functional adaptation of a cortical bone involves a change in bone quality determined by the preferential orientation of apatite nano-crystallite, a key component of the bone. An in vivo rat ulnar axial loading model was adopted, to which a 3–15 N compressive load was applied, resulting in approximately 440–3200 μɛ of compression in the bone surface. In the loaded ulnae, the degree of preferential apatite c-axis orientation along the ulnar long axis increased in a dose-dependent manner up to 13 N, whereas the increase in BMD was not dose-dependent. The Young's modulus along the same direction was enhanced as a function of the degree of apatite orientation. This finding indicates that bone has a mechanism that modifies the directionality (anisotropy) of its microstructure, strengthening itself specifically in the loaded direction. BMD, a scalar quantity, does not allow for load-direction-specific strengthening. Functional adaptation through changes in apatite orientation is an excellent strategy for bones to efficiently change their strength in response to external loading, which is mostly anisotropic.
AB - Functional adaptation refers to the active modification of bone structure according to the mechanical loads applied daily to maintain its mechanical integrity and adapt to the environment. Functional adaptation relates to bone mass, bone mineral density (BMD), and bone morphology (e.g., trabecular bone architecture). In this study, we discovered for the first time that another form of bone functional adaptation of a cortical bone involves a change in bone quality determined by the preferential orientation of apatite nano-crystallite, a key component of the bone. An in vivo rat ulnar axial loading model was adopted, to which a 3–15 N compressive load was applied, resulting in approximately 440–3200 μɛ of compression in the bone surface. In the loaded ulnae, the degree of preferential apatite c-axis orientation along the ulnar long axis increased in a dose-dependent manner up to 13 N, whereas the increase in BMD was not dose-dependent. The Young's modulus along the same direction was enhanced as a function of the degree of apatite orientation. This finding indicates that bone has a mechanism that modifies the directionality (anisotropy) of its microstructure, strengthening itself specifically in the loaded direction. BMD, a scalar quantity, does not allow for load-direction-specific strengthening. Functional adaptation through changes in apatite orientation is an excellent strategy for bones to efficiently change their strength in response to external loading, which is mostly anisotropic.
KW - Apatite orientation
KW - Bone quality
KW - Bone strength
KW - Functional adaptation
KW - In vivo loading
UR - http://www.scopus.com/inward/record.url?scp=85183520595&partnerID=8YFLogxK
U2 - 10.1016/j.bone.2024.117024
DO - 10.1016/j.bone.2024.117024
M3 - 学術論文
C2 - 38266952
AN - SCOPUS:85183520595
SN - 8756-3282
VL - 181
JO - Bone
JF - Bone
M1 - 117024
ER -