Cen Haipeng, Gong He, Liu Haibo, Jia Shaowei, Wu Xiaodan, Fan Yubo
Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
School of Engineering Medicine, Beihang University, Beijing, China.
Front Bioeng Biotechnol. 2022 May 5;10:893337. doi: 10.3389/fbioe.2022.893337. eCollection 2022.
Femoral neck fracture (FNF) is the most serious bone disease in the elderly population. The multiscale mechanical response is a key to predicting the strength of the femoral neck, assessing the risk of FNF, and exploring the role of mechanosensation and mechanotransmission in bone remodeling, especially in the context of aging bone. Multiscale finite element (FE) models of the proximal femur for both young and elderly people were developed. The models included organ scale (proximal femur), tissue scale (cortical bone), tissue element scale (osteon), and cell scale [osteocyte lacuna-canalicular network (LCN) and extracellular matrix (ECM), OLCEM]. The mechanical responses of cortical bone and osteocytes in the mid-femoral neck and the differences in mechanical responses between these two scales were investigated. The mechanical responses of cortical bone and osteocyte showed significant differences between the elderly and the young. The minimum principal strains and mean SEDs of cortical bone in the elderly were 2.067-4.708 times and 3.093-14.385 times of the values in the young, respectively; the minimum principal strains and mean SEDs of osteocyte in the elderly were 1.497-3.246 times and 3.044-12 times of the values in the young, respectively; the amplification factors of minimum principal strain in the inferior (Inf), anterior (Ant), and posterior (Post) quadrants in the young were 1.241-1.804 times of the values in the elderly, but the amplification factor of minimum principal strain in the superior (Sup) quadrant was 87.4% of the value in the elderly; the amplification factors of mean SED in the young were 1.124-9.637 times of the values in the elderly. The mass and bone mineral density (BMD) of cortical bone in the femoral neck is closely related to the mechanical response of osteocytes, which provides a new idea for improving cortical bone quality. Perhaps cortical bone quality could be improved by stimulating osteocytes. Quadrantal differences of bone quality in the mid-femoral neck should be considered to improve fracture risk prediction in the future.
股骨颈骨折（FNF）是老年人群中最严重的骨病。多尺度力学响应是预测股骨颈强度、评估FNF风险以及探索机械感受和机械转导在骨重塑（尤其是在衰老骨骼背景下）中作用的关键。建立了年轻人和老年人近端股骨的多尺度有限元（FE）模型。这些模型包括器官尺度（近端股骨）、组织尺度（皮质骨）、组织单元尺度（骨单位）和细胞尺度[骨细胞陷窝 - 小管网络（LCN）和细胞外基质（ECM），OLCEM]。研究了股骨颈中部皮质骨和骨细胞的力学响应以及这两个尺度之间力学响应的差异。皮质骨和骨细胞的力学响应在老年人和年轻人之间存在显著差异。老年人皮质骨的最小主应变和平均应变能密度分别是年轻人的2.067 - 4.708倍和3.093 - 14.385倍；老年人骨细胞的最小主应变和平均应变能密度分别是年轻人的1.497 - 3.246倍和3.044 - 12倍；年轻人下（Inf）、前（Ant）和后（Post）象限的最小主应变放大因子是老年人的1.241 - 1.804倍，但上（Sup）象限的最小主应变放大因子是老年人的87.4%；年轻人平均应变能密度的放大因子是老年人的1.124 - 9.637倍。股骨颈皮质骨的质量和骨密度（BMD）与骨细胞的力学响应密切相关，这为改善皮质骨质量提供了新思路。或许可以通过刺激骨细胞来改善皮质骨质量。未来改善骨折风险预测时应考虑股骨颈中部骨质量的象限差异。
