Boivin G, Meunier P J
INSERM Unité 403, Faculté de Médecine R. Laennec, 69372 Lyon Cedex 08, France.
Calcif Tissue Int. 2002 Jun;70(6):503-11. doi: 10.1007/s00223-001-2048-0. Epub 2002 May 27.
Strength of bones depends on bone matrix volume (BMV), bone microarchitecture, but also bone mineralization, and we have recently shown in osteoporotic patients treated with alendronate that fracture risk and bone mineral density (BMD) were changed without modifications of BMV or bone microarchitecture. Mineralization of bone matrix implies two successive steps: a rapid primary mineralization on the calcification front followed by a slow process of secondary mineralization progressively adding about one-half of the mineral content on bone matrix. These two steps are clearly illustrated by microradiographs of compact and cancellous bone tissue from transiliac human biopsies. Our working hypothesis is based on the impact of changes in bone remodeling rate on the degree of mineralization of bone, i.e., on the BMD measured at the tissue level. Contact quantitative microradiography using a computerized microdensitometric method, is described and allows the measurement of the mean degree of mineralization of bone (MDMB). This parameter may be quantitatively evaluated by exposing an aluminum calibration step-wedge and a plane-parallel calcified tissue section simultaneously to the same beam of X-rays, then determining, from the resulting microradiograph, the thickness of aluminum that produces the same X-ray absorption as a given region of the bone tissue section. To be used as a control group, iliac bone samples were taken at necropsy from 43 subjects (30 women aged 48.4 +/- 3.7 years and 13 men aged 66.0 +/- 4.4 years) who died suddenly showing no apparent bone disease. A control MDMB, which does not change with age, and a control distribution of these values are thus established. These control values are necessary for interpreting the changes in MDMB observed in bone conditions untreated or treated.
骨骼强度取决于骨基质体积（BMV）、骨微结构，还取决于骨矿化，并且我们最近在接受阿仑膦酸盐治疗的骨质疏松症患者中发现，骨折风险和骨密度（BMD）发生了变化，而BMV或骨微结构并未改变。骨基质的矿化包括两个连续步骤：在钙化前沿快速进行初级矿化，随后是缓慢的次级矿化过程，该过程逐渐在骨基质上增加约一半的矿物质含量。来自人髂骨活检的致密和松质骨组织的显微放射照片清楚地说明了这两个步骤。我们的工作假设基于骨重塑率变化对骨矿化程度的影响，即对在组织水平测量的BMD的影响。描述了使用计算机微密度测定法的接触定量显微放射摄影术，它可以测量骨的平均矿化程度（MDMB）。通过将铝校准楔形物和平面平行钙化组织切片同时暴露于同一束X射线下，然后从所得的显微放射照片中确定产生与骨组织切片给定区域相同X射线吸收的铝的厚度，可以定量评估该参数。作为对照组，在尸检时从43名受试者（30名年龄为48.4±3.7岁的女性和13名年龄为66.0±4.4岁的男性）中获取髂骨样本，这些受试者突然死亡，未显示明显的骨病。由此建立了不随年龄变化的对照MDMB及其这些值的对照分布。这些对照值对于解释在未治疗或治疗的骨状况中观察到的MDMB变化是必要的。
