Degradation and Recovery of Bone: OVX and Treatment

描述（由申请方提供）：骨质疏松相关骨折仅部分可通过随年龄增长而普遍发生的骨量减少来解释。预测骨折的失败部分来自a）当使用投影X射线方法测量骨量时几何信息的丢失，B）忽略关于骨的失效特性的足够详细的信息，以及c）忽略骨上的详细体内载荷（骨折风险与载荷与强度的比率有关，而不是单独与骨强度有关）。准确预测骨折风险的第四个障碍是由年龄或疾病相关的骨胶原、非胶原蛋白或水含量的变化引起的骨组织机械性能的变化不能用X射线方法检测。由于软组织变化对X射线检测的不可见性，组织材料性质（骨质）中存在年龄和绝经相关的变化，这些变化是不可见的、不被理解的，并且不可预测地增加骨折风险。 我们的数据支持新的工作假设：1）骨的粘弹性影响骨组织的断裂韧性和表观强度，2）羊骨的粘弹性在卵巢切除术后降解，导致骨组织的强度和断裂韧性降低与福尔斯相关的负荷率。 所提出的工作的主要目标是确定粘弹性性能退化的开始时间和皮质骨是否可以恢复正常的粘弹性和强度性能与雌激素替代。

DESCRIPTION (provided by applicant): Age-related bone fracture is only partially explained by the reduction in bone mass that universally occurs with aging. The failure to predict fracture comes in part from a) the loss of geometrical information when projection x-ray methods are used to measure bone mass, b) ignorance of sufficiently detailed information about the failure properties of bone, and also c) ignorance of detailed in vivo loads on bones (Fracture risk is related to the ratio of load to strength, rather than to bone strength alone). A fourth barrier to accurately predicting fracture risk is that changes in bone tissue mechanical properties caused by age or disease related changes in the collagen, non-collagenous proteins or water content of bone are not detectable to xray methods. As a result of the invisibility of soft tissue changes to x-ray detection, there are age and menopause related changes in tissue material properties (in bone quality) that are invisible, not understood and that unpredictably increase bone fracture risk. Our data support the novel working hypotheses: 1) The viscoelastic properties of bone affect the fracture toughness and apparent strength of bone tissue, 2) The viscoelastic properties of ovine bone degrade after ovariectomy, causing a decrease in the strength and fracture toughness of bone tissue for rates of loading associated with falls. The main goal of the proposed work is to determine the onset time of viscoelastic property degradation and whether cortical bone can recover normal viscoelastic and strength properties with estrogen replacement.