Osteoporosis affects both post-yield microdamage accumulation and plasticity degradation in vertebra of ovariectomized rats  

作　　者：Siwei Li Guodong Niu Neil X. Dong Xiaodu Wang Zhongjun Liu Chunli Song Huijie Leng 

机构地区：[1]Department of Orthopedics, Peking University Third Hospital, Beijing 100191, China [2]Department of Orthopedics, Ansteel Group Hospital,Anshan 114003, China [3]Beijing Key Lab of Spine Diseases, Beijing 100191, China [4]Department of Health and Kinesiology, University of Texas at Tyler, Tyler, TX 75799, USA [5]Department of Mechanical Engineering, University of Texas at San Antonio, San Antonio, TX 78249, USA

出　　处：《Acta Mechanica Sinica》2017年第2期267-273,共7页力学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grants 11472017, 11002004)

摘　　要：Estrogen withdrawal in postmenopausal women increases bone loss and bone fragility in the vertebra. Bone loss with osteoporosis not only reduces bone mineral density (BMD), but actually alters bone quality, which can be comprehensively represented by bone post-yield behaviors. This study aimed to provide some information as to how osteoporosis induced by estrogen depletion could influence the evolution of post-yield microdamage accumulation and plastic deformation in vertebral bodies. This study also tried to reveal the part of the mechanisms of how estrogen deficiency-induced osteoporosis would increase the bone fracture risk. A rat bilateral ovariectomy (OVX) model was used to induce osteoporosis. Progressive cyclic compression loading was developed for vertebra testing to elucidate the post-yield behaviors. BMD, bone volume fraction, stiffness degradation, and plastic deformation evolution were compared among rats raised for 5 weeks (ovx5w and sham5w groups) and 35 weeks (ovx35w and sham35w groups) after sham surgery and OVX. The results showed that a higher bone loss in vertebral bodies corresponded to lower stiffness and higher plastic deformation. Thus, osteoporosis could increase the vertebral fracture risk probably through microdamage accumulation and plastic deforming degradation.Estrogen withdrawal in postmenopausal women increases bone loss and bone fragility in the vertebra. Bone loss with osteoporosis not only reduces bone mineral density (BMD), but actually alters bone quality, which can be comprehensively represented by bone post-yield behaviors. This study aimed to provide some information as to how osteoporosis induced by estrogen depletion could influence the evolution of post-yield microdamage accumulation and plastic deformation in vertebral bodies. This study also tried to reveal the part of the mechanisms of how estrogen deficiency-induced osteoporosis would increase the bone fracture risk. A rat bilateral ovariectomy (OVX) model was used to induce osteoporosis. Progressive cyclic compression loading was developed for vertebra testing to elucidate the post-yield behaviors. BMD, bone volume fraction, stiffness degradation, and plastic deformation evolution were compared among rats raised for 5 weeks (ovx5w and sham5w groups) and 35 weeks (ovx35w and sham35w groups) after sham surgery and OVX. The results showed that a higher bone loss in vertebral bodies corresponded to lower stiffness and higher plastic deformation. Thus, osteoporosis could increase the vertebral fracture risk probably through microdamage accumulation and plastic deforming degradation.

关 键 词：OSTEOPOROSIS Bone mineral density Vertebral body Post-yield MICRODAMAGE PLASTICITY 

分 类 号：R580[医药卫生—内分泌]