Metabolic Bone Diseases Unit, Division of Endocrinology, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
J Bone Miner Res. 2013 May;28(5):1029-40. doi: 10.1002/jbmr.1841.
Typically, in the milder form of primary hyperparathyroidism (PHPT), now seen in most countries, bone density by dual-energy X-ray absorptiometry (DXA) and detailed analyses of iliac crest bone biopsies by histomorphometry and micro-computed tomography (µCT) show detrimental effects in cortical bone, whereas the trabecular site (lumbar spine by DXA) and the trabecular compartment (by bone biopsy) appear to be relatively well preserved. Despite these findings, fracture risk at both vertebral and nonvertebral sites is increased in PHPT. Emerging technologies, such as high-resolution peripheral quantitative computed tomography (HRpQCT), may provide additional insight into microstructural features at sites such as the forearm and tibia that have heretofore not been easily accessible. Using HRpQCT, we determined cortical and trabecular microstructure at the radius and tibia in 51 postmenopausal women with PHPT and 120 controls. Individual trabecula segmentation (ITS) and micro-finite element (µFE) analyses of the HRpQCT images were also performed to further understand how the abnormalities seen by HRpQCT might translate into effects on bone strength. Women with PHPT showed, at both sites, decreased volumetric densities at trabecular and cortical compartments, thinner cortices, and more widely spaced and heterogeneously distributed trabeculae. At the radius, trabeculae were thinner and fewer in PHPT. The radius was affected to a greater extent in the trabecular compartment than the tibia. ITS analyses revealed, at both sites, that plate-like trabeculae were depleted, with a resultant reduction in the plate/rod ratio. Microarchitectural abnormalities were evident by decreased plate-rod and plate-plate junctions at the radius and tibia, and rod-rod junctions at the radius. These trabecular and cortical abnormalities resulted in decreased whole-bone stiffness and trabecular stiffness. These results provide evidence that in PHPT, microstructural abnormalities are pervasive and not limited to the cortical compartment, which may help to account for increased global fracture risk in PHPT.
通常，在大多数国家中更为常见的轻度原发性甲状旁腺功能亢进症（PHPT）中，双能 X 射线吸收法（DXA）测量的骨密度和组织形态计量学及微计算机断层扫描（µCT）对髂嵴骨活检的详细分析显示皮质骨有不利影响，而松质骨部位（DXA 测量腰椎）和松质骨腔室（骨活检测量）似乎相对保存完好。尽管有这些发现，但 PHPT 患者的椎体和非椎体部位的骨折风险均增加。新兴技术，如高分辨率外周定量计算机断层扫描（HRpQCT），可能会提供有关前臂和胫骨等以前不易获取的部位的微观结构特征的更多见解。使用 HRpQCT，我们在 51 名患有 PHPT 的绝经后妇女和 120 名对照者中测定了桡骨和胫骨的皮质和松质微观结构。还对 HRpQCT 图像进行了单独的小梁分割（ITS）和微有限元（µFE）分析，以进一步了解 HRpQCT 所见的异常如何转化为对骨强度的影响。在两个部位，PHPT 患者的骨小梁和皮质腔室的体积密度均降低，皮质变薄，骨小梁更宽且分布不均。在桡骨中，PHPT 患者的骨小梁更细，数量更少。桡骨比胫骨更易受影响。在两个部位，ITS 分析均显示板状小梁减少，导致板/杆比降低。桡骨和胫骨的板-杆和板-板连接以及桡骨的杆-杆连接减少，表明微结构异常。这些骨小梁和皮质异常导致全骨刚度和骨小梁刚度降低。这些结果表明，在 PHPT 中，微观结构异常普遍存在，不仅限于皮质腔室，这可能有助于解释 PHPT 中总体骨折风险增加的原因。
