When BMD is under 0.6 g/cm2,the trabecula is destroyed in both transverse and longitudinal orientation,while the collagen fiber emerges the convolution and rupture.

• 在骨密度<0.；6g/cm2时；骨小梁横向和纵向均遭到破坏；骨胶原纤维同时出现卷曲、断裂。