A multi-factorial analysis of bone morphology and fracture strength of rat femur in response to ovariectomy
A multi-factorial analysis of bone morphology and fracture strength of rat femur in response to ovariectomy
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DOI：
10.1186/s13018-018-1018-4
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发表时间：
2018-12-13
影响因子：
2.6
通讯作者：
Uoshima, Katsumi
中科院分区：
文献类型：
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作者：
Rocabado, Juan Marcelo Rosales;Kaku, Masaru;Uoshima, Katsumi
绝经后骨质疏松症是由于雌激素缺乏导致骨量减少和骨的宏观和微观结构改变，导致机械强度丧失和骨折风险增加所致。尽管骨密度(BMD)评估已被广泛用作诊断筛查骨折风险的金标准，但它只占骨脆性变异的一部分；因此，有必要考虑骨强度的其他决定因素。因此，我们旨在综合评价影响骨断裂强度的骨结构变化，以及皮质和松质骨对卵巢切除(OVX)的不同敏感性。方法分别分析去卵巢大鼠股骨皮质骨和松质骨、远端干骺端和骨干中段的骨形态参数。在股骨干中段进行三点弯曲试验。用Pearson相关系数分析OVX引起的骨形态参数变化与破裂力的相关性。结果OVX导致远端干骺端松质骨骨体积减少，远端干端和骨干中段皮质骨体积增加。骨干远端的松质骨和皮质骨的组织密度(TMD)无明显变化，而骨干中段的皮质骨的组织密度(TMD)有所下降。OVX可显著增加股骨干中段的折断力。结论OVX使远端干骺端的骨小梁体积减少，远端和中段的皮质骨体积增加。尽管OVX后TMD减少，皮质孔隙率增加，但骨干中段的骨折强度增加。这些结果表明，分析单一因素，即骨密度，不足以预测骨骼的绝对骨折风险，因为OVX引起的骨反应因骨骼类型和位置而异。我们的结果有力地支持了分析骨骼微结构和部位特异性的必要性，以在临床环境下阐明骨质疏松症的真正病因。
BackgroundPostmenopausal osteoporosis develops due to a deficiency of estrogen that causes a decrease in bone mass and changes in the macro- and micro-architectural structure of the bone, leading to the loss of mechanical strength and an increased risk of fracture. Although the assessment of bone mineral density (BMD) has been widely used as a gold standard for diagnostic screening of bone fracture risks, it accounts for only a part of the variation in bone fragility; thus, it is necessary to consider other determinants of bone strength. Therefore, we aimed to comprehensively evaluate the architectural changes of the bone that influence bone fracture strength, together with the different sensitivities of cortical and trabecular bone in response to ovariectomy (OVX).MethodsBone morphology parameters were separately analyzed both in cortical and in trabecular bones, at distal-metaphysis, and mid-diaphysis of OVX rat femurs. Three-point bending test was performed at mid-diaphysis of the femurs. Correlation of OVX-induced changes of morphological parameters with breaking force was analyzed using Pearson's correlation coefficient.ResultsOVX resulted in a decline in the bone volume of distal-metaphysis trabecular bone, but an increase in distal-metaphysis and mid-diaphysis cortical bone volume. Tissue mineral density (TMD) remained unchanged in both the trabecular and cortical bone of the distal metaphysis but decreased in cortical bone of the mid-diaphysis. The OVX significantly increased the breaking force at mid-diaphysis of the femurs.ConclusionsOVX decreased the trabecular bone volume of the distal-metaphysis and increased the cortical bone volume of the distal-metaphysis and mid-diaphysis. Despite the reduction in TMD and increased cortical porosity, bone fracture strength increased in the mid-diaphysis after OVX. These results indicate that analyzing a single factor, i.e., BMD, is not sufficient to predict the absolute fracture risk of the bone, as OVX-induced bone response vary, depending on the bone type and location. Our results strongly support the necessity of analyzing bone micro-architecture and site specificity to clarify the true etiology of osteoporosis in a clinical setting.