Science & Engineering Faculty and Institute of Health & Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia; The University College in Al-Qunfudah, Umm Al-Qura University, Saudi Arabia.
Science & Engineering Faculty and Institute of Health & Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia.
Bone. 2018 Feb;107:145-153. doi: 10.1016/j.bone.2017.11.021. Epub 2017 Dec 2.
Conventional mechanical testing is the 'gold standard' for assessing the stiffness (N mm) and strength (MPa) of bone, although it is not applicable in-vivo since it is inherently invasive and destructive. The mechanical integrity of a bone is determined by its quantity and quality; being related primarily to bone density and structure respectively. Several non-destructive, non-invasive, in-vivo techniques have been developed and clinically implemented to estimate bone density, both areal (dual-energy X-ray absorptiometry (DXA)) and volumetric (quantitative computed tomography (QCT)). Quantitative ultrasound (QUS) parameters of velocity and attenuation are dependent upon both bone quantity and bone quality, although it has not been possible to date to transpose one particular QUS parameter into separate estimates of quantity and quality. It has recently been shown that ultrasound transit time spectroscopy (UTTS) may provide an accurate estimate of bone density and hence quantity. We hypothesised that UTTS also has the potential to provide an estimate of bone structure and hence quality. In this in-vitro study, 16 human femoral bone samples were tested utilising three techniques; UTTS, micro computed tomography (μCT), and mechanical testing. UTTS was utilised to estimate bone volume fraction (BV/TV) and two novel structural parameters, inter-quartile range of the derived transit time (UTTS-IQR) and the transit time of maximum proportion of sonic-rays (TTMP). μCT was utilised to derive BV/TV along with several bone structure parameters. A destructive mechanical test was utilised to measure the stiffness and strength (failure load) of the bone samples. BV/TV was calculated from the derived transit time spectrum (TTS); the correlation coefficient (R) with μCT-BV/TV was 0.885. For predicting mechanical stiffness and strength, BV/TV derived by both μCT and UTTS provided the strongest correlation with mechanical stiffness (R=0.567 and 0.618 respectively) and mechanical strength (R=0.747 and 0.736 respectively). When respective structural parameters were incorporated to BV/TV, multiple regression analysis indicated that none of the μCT histomorphometric parameters could improve the prediction of mechanical stiffness and strength, while for UTTS, adding TTMP to BV/TV increased the prediction of mechanical stiffness to R=0.711 and strength to R=0.827. It is therefore envisaged that UTTS may have the ability to estimate BV/TV along with providing an improved prediction of osteoporotic fracture risk, within routine clinical practice in the future.
传统的机械测试是评估骨骼刚度（Nmm）和强度（MPa）的“金标准”，尽管它不适用于体内，因为它具有内在的侵入性和破坏性。骨骼的机械完整性取决于其数量和质量；主要与骨密度和结构分别相关。已经开发并临床实施了几种非破坏性、非侵入性、体内技术来估计骨密度，包括面积（双能 X 射线吸收法（DXA））和体积（定量计算机断层扫描（QCT））。超声速度和衰减的定量超声（QUS）参数既依赖于骨量又依赖于骨质量，尽管迄今为止还不可能将一个特定的 QUS 参数转换为对数量和质量的单独估计。最近表明，超声渡越时间光谱（UTTS）可能提供骨密度的准确估计，因此数量。我们假设 UTTS 也有可能提供对骨结构的估计，从而提供质量。在这项体内研究中，使用三种技术对 16 个人类股骨骨样本进行了测试；UTTS、微计算机断层扫描（μCT）和机械测试。UTTS 用于估计骨体积分数（BV/TV）和两个新的结构参数，导出渡越时间的四分位范围（UTTS-IQR）和最大比例声射线的渡越时间（TTMP）。μCT 用于从衍生的渡越时间谱（TTS）中推导出 BV/TV，以及几个骨结构参数。破坏性机械试验用于测量骨样本的刚度和强度（破坏载荷）。从导出的渡越时间谱中计算出 BV/TV；与μCT-BV/TV 的相关系数（R）为 0.885。对于预测机械刚度和强度，μCT 和 UTTS 分别推导出的 BV/TV 与机械刚度（R=0.567 和 0.618）和机械强度（R=0.747 和 0.736）具有最强的相关性。当将各自的结构参数合并到 BV/TV 中时，多元回归分析表明，μCT 组织形态计量学参数均无法提高机械刚度和强度的预测能力，而对于 UTTS，将 TTMP 添加到 BV/TV 中可将机械刚度的预测提高到 R=0.711，将强度的预测提高到 R=0.827。因此，可以预见，UTTS 可能具有估计 BV/TV 以及提供骨质疏松性骨折风险预测的能力，这在未来的常规临床实践中是可行的。
