J.Biomechanics：早期骨折检测应同时注重定性定量指标
精确地在体评价骨的性能对骨质疏松、微重力影响、长期卧床和假体的应力遮挡等问题具有重要意义，从生理学和骨丢失方面进行骨折风险早期检测是具有广阔应用前景的手段。骨矿物质密度作为一种传统的量化指标有广泛的应用，另外结构镜像参数作为定性指标也被提出来以更精确地测量骨的力学性质。
为进一步评价力学性质和骨小梁结构之间的关系，在美国国家空间生物医学研究所的资助下，科学家采用力学测试、双能量X射线吸收测定术（DXA）和微CT技术对人尸体跟骨标本进行测量。这项研究在三维上进行了方向个性化结构性质评定，并与力学测试和DXA测量相关。研究结果显示，微CT所测量的体积分数和结构模型指数等骨特性指标，比DXA方法测量的骨矿物质密度能更好地预测弹性模量、屈服应力和极限应力等骨的力学性质。从临床诊断上来说，这意味着在今后的骨折风险早期检测中要同时注重骨的定性和定量指标。研究结果也显示，骨丢失主要影响到骨小梁的连通性和整体数量。但是骨的极限应力与骨小梁数目的相关性比与骨小梁厚度的相关性更大，随着微CT的普及，对这种技术的研究和应用将逐步得到推广。
相关论文发表在爱思唯尔期刊《生物力学杂志》（Journal of Biomechanics）上。（科学新闻杂志 牛文鑫/编译）
生物谷推荐原始出处：
（Journal of Biomechanics），Volume 41, Issue 2, 2008, Pages 368-375，Erik Mittra，Yi-Xian Qin
Evaluation of trabecular mechanical and microstructural properties in human calcaneal bone of advanced age using mechanical testing, μCT, and DXA
Erik Mittraa, Clinton Rubinb, Barry Gruberc and Yi-Xian Qinb, 
, 
aDepartment of Radiology-Nuclear Medicine, Stanford University Medical Center, 300 Pasteur Dr., Rm. H0101, Stanford, CA 94305, USA
bDepartment of Biomedical Engineering, Stony Brook University, NY, USA
cDepartment of Internal Medicine, Stony Brook University, NY, USA
Accepted 1 September 2007. Available online 22 October 2007.
Abstract
Early detection of fracture risk is important for initiating treatment and improving outcomes from both physiologic and pathologic causes of bone loss. While bone mineral density (a quantity measure) has traditionally been used for this purpose, alternative structural imaging parameters (quality measures) are proposed to better predict bone's true mechanical properties. To further elucidate this, trabecular bone from cadaveric human calcanei were used to evaluate the interrelationship of mechanical and structural parameters using mechanical testing, dual energy X-ray absorptiometry (DXA) scanning, and micro computed tomography (μCT) imaging. Directional specific structural properties were assessed in three-dimensional (3-D) and correlated to mechanical testing and DXA. The results demonstrated that μCT-derived indices of bone quality (i.e., volume fraction and structural model index) are better than DXA-derived bone mineral density for the prediction of the mechanical parameters of bone (i.e., elastic modulus, yield stress, and ultimate stress). Diagnostically, this implies that future work on the early prediction of fracture risk should focus as much on bone quality as on quantity. Furthermore, the results of this study show that a loss of bone primarily affects the connectedness and overall number of trabeculae. Ultimate stress, however, is better correlated with trabecular number than thickness. As such, primary prevention of osteoporosis may be more important than later countermeasures for bone loss.
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