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目的探讨模拟失重下雌、雄性大鼠影像学参数预测骨折风险相关性及性别差异的原因。方法 3月龄雌、雄性SD大鼠40只,按性别及是否失重随机分为4组,4周后,双能X线检测L4椎体、股骨BMD,Micro-CT分析骨小梁结构,生物力学测试力学强度。结果失重4周后,雌性组子宫重量降低47.3%,雄性组精囊重量降低39.5%。失重试验组BMD显著下降,骨体积分数(BV/TV)、骨小梁厚度(Tb.Th)、骨小梁数目(Tb.N)显著降低(P<0.05),骨小梁间隙(Tb.Sp)显著增加;悬吊组椎体的最大压缩载荷(N)、压缩压力(MPa)、抗弯曲载荷(N)较对照组显著下降。BMD、BV/TV、Tb.Th、Tb.N、Tb.Sp与最大力学强度Fmax相关性系数r,雄性组为0.985、0.995、0.948、0.957、-0.990,雌性组为0.908、0.899、0.873、0.852、-0.76。结论失重4周后,不同性别大鼠BMD明显降低,激素水平的影响可能是模拟失重雌性大鼠骨丢失更严重原因之一。骨密度与失重后生物力学的相关性可综合有效地预测失重后的骨折风险。
Objective To investigate the correlation between the risk of fracture and the gender difference in imaging parameters of female and male rats under simulated weightlessness. Methods Forty male and female 3-month-old male and female SD rats were randomly divided into 4 groups according to gender and weight loss. Four weeks later, L4 vertebra, femoral BMD and Micro-CT were analyzed by dual-energy X-ray. Trabecular structure, Mechanical test Mechanical strength. Results After 4 weeks of weightlessness, the weight of uterus in female group decreased by 47.3% and the weight of seminal vesicles in male group decreased by 39.5%. BMD of weight loss test group decreased significantly, BV / TV, Tb.Th and Tb.N decreased (P <0.05), and trabecular bone gap (Tb. Sp significantly increased; the maximum compressive load (N), compressive stress (MPa) and bending load (N) of the vertebral suspension group decreased significantly compared with the control group. The correlation coefficient r of BMD, BV / TV, Tb.Th, Tb.N, Tb.Sp and maximum mechanical strength Fmax were 0.985,0.995,0.948,0.957 and -0.990 in the male group, 0.908,0.899 and 0.873 in the female group, 0.852, -0.76. Conclusion After 4 weeks of weightlessness, the BMD in different sexes decreased significantly. The effect of hormones may be one of the more serious causes of bone loss in simulated weightless female rats. The correlation between BMD and post-weightless biomechanics can predict the risk of fracture after weightlessness comprehensively and effectively.