松质骨显微结构参数与表观力学强度关系研究进展

通过双能X射线吸收法测量受试者的骨密度,是目前公认的诊断骨质疏松症的方法。然而,越来越多的基础和临床研究发现,骨密度的改变并不能完全解释患者骨强度的改变。大量的骨组织显微结构研究发现,松质骨的骨强度主要由骨密度、骨结构等因素决定。近年来的研究表明,在决定松质骨骨骼强度方面,骨组织的显微结构可以作为独立于骨密度之外的决定性参数。研究松质骨的力学属性和显微结构之间的关系,对于更好的理解骨质疏松的发生和对骨质疏松的诊断具有十分重要的意义。根据文献回顾,松质骨显微结构参数和表观力学强度之间关联性最为显著的为BV／TV、Tb．N、连接性、各向异性、结构模型指数等。同时笔者也对目前这些研究结果在临床上高分辨率CT上的应用情况做一总结。     

瘦素缺乏小鼠椎体骨质的Micro-CT评价

目的探讨瘦素通过对椎体骨质代谢的影响,从而进一步影响椎间盘退变的可能性。方法获取12个6月龄雄性ob/ob小鼠(瘦素缺乏小鼠)和野生型小鼠(C57BL小鼠)的腰5椎体(各6个),通过Micro-CT检测比较两者骨密度、皮质骨厚度、小梁骨体积、小梁骨厚度、小梁骨数量、连接性密度、结构模型指数等显微结构参数的差异。结果与野生型小鼠相比较,6月龄ob/ob小鼠的椎体骨密度及小梁骨厚度增大,椎体连接性密度(Conn.D)明显增加;椎体骨小梁间隙明显减少;椎体结构模型指数(SMI)明显减小,两者比较差异均有显著统计学意义(P0.01);其小梁骨体积((BV/TV)、小梁骨数量增加、皮质骨厚度增大,两者比较差异均有统计学意义(P0.05)。结论瘦素可能通过对小鼠椎体骨质代谢影响椎间盘的营养供应从而进一步影响椎间盘的退变。     

仿生双相磷酸钙生物陶瓷支架的Micro-CT评价

[目的]体外用Micro-CT(Micro-computed tomography)图像对仿生双相磷酸钙生物陶瓷支架的三维结构进行计算机重建和评价.[方法]犬股骨头的松质骨样本行Micro-CT扫描,提取图像信息;三维凝胶叠层成型法制备出具有仿骨小梁结构的双相磷酸钙仿生生物陶瓷支架.随后用Micro-CT对支架扫描,以三维结构参数对支架和松质骨样本作三维评价和比较.三维参数包括:骨体积分数(Bone Volume Fraction,BVF,BV/TV)、骨表面积体积比(Bone surface/bone volume ratio,BS/BV)、骨小梁厚度(Trabecular thickness,TbTh)、骨小梁数目(Trabecular number,TbN)、骨小梁间隙(Trabecular spacing,TbSp)、结构模型指数(Structure Model Index,SMl)和各向异性程度(degree of anisoropy,DA).[结果]与犬股骨头松质骨样本相比,用本方法制备出的BCP支架具有相似的三维空间结构,二者的BV/TV、TbTh、TbN无显著差别(P＞0.05).小梁结构呈板状模型.[结论]本研究制备的BCP多孔支架的小梁具有一定的取向性,力学强度和良好的适于血管长入的空间结构.     

雷尼酸锶对局部肌麻痹大鼠的骨量丢失及微结构退变的影响

目的 研究雷尼酸锶对局部肌肉麻痹大鼠的骨量丢失及微结构退变的影响。方法 21只3.5月龄的雌性SD大鼠随机分三组,每组各7只：肉毒素组(BTX组),右侧股四头肌肌注肉毒素建立局部肌肉麻痹废用模型;肉毒素+雷尼酸锶组(BTX+SR组),肌注肉毒素并予以雷尼酸锶灌胃处理;对照组。所有大鼠干预9周后处死,取双侧股骨,行显微CT扫描分析。结果 BTX组与对照组相比较,废用侧的股骨皮质骨矿物盐含量、皮质骨骨密度、皮质骨面积和截面总面积以及松质骨的骨体积分数、骨小梁厚度、骨小梁数量和骨小梁联接密度均明显下降;骨小梁面积分数、骨小梁间隔和结构模型指数显著增加(P＜0.05)。BTX+SR组与BTX组相比较,皮质骨骨密度、皮质骨面积和截面总面积以及松质骨的组织骨密度、骨体积分数、骨小梁厚度、骨小梁数量和骨小梁联接密度明显增加,骨小梁面积分数、骨小梁间隔和结构模型指数显著下降(P＜0.05)。BTX+SR组与BTX组和对照组比较,健侧松质骨的表观骨密度、组织骨密度、骨体积分数和骨小梁厚度均明显增加(P＜0.05)。结论 雷尼酸锶可阻止因局部肌肉麻痹导致的大鼠骨量丢失和微结构的退变。     

正常人股骨近端生物力学性能的区域性分析

目的 分析股骨近端不同区域松质骨的显微结构及生物力学性能的差异性,为合理设计金属置人物提供力学参考.方法 取7个新鲜正常人体股骨近端标本,进行Micro-CT扫描,分别对股骨头、股骨颈、粗隆间的骨小梁的结构参数进行分析,并结合大型有限元三维有限元对比分析各区域在主要受力方向上的生物力学性能.结果 股骨头部的骨密度、骨矿含量、骨小梁密度、骨小梁数目明显高于股骨颈及粗隆间,差异有统计学意义(P＜0.05),股骨颈与粗隆间相比则差异无统计学意义(P＞0.05).结论 股骨近端不同区域的松质骨的显微结构及生物力学性能存在差异性,提示现有股骨近端金属置人物可能存在生物力学上的缺陷.     

股骨头松质骨样本空间结构的三维分析

目的在股骨头坏死和骨质疏松股骨颈骨折的研究中,股骨头松质骨的空间结构的重要性越来越受到重视。本研究介绍一种对股骨头松质骨样本的骨小梁的空间结构进行三维重建和评价的方法。方法对8个犬股骨头的松质骨样本进行硝酸银染色和白色聚酯包埋后,逐层连续断面切除,利用数码CCD镜头连续采集断面图像,获取样本断面的二维图像,利用计算机软件二值化图像,并进行三维重建,得到松质骨小梁空间结构的计算机三维图形,对样本进行三维评测,指标包括骨体积分数(BoneVolumeFraction,BVF,BV/TV)、骨表面积体积比(Bonesurface/bonevolumeratio,BS/BV)、骨小梁厚度(Trabecularthickness,Tb.Th)、骨小梁数目(Trabecularnumber,Tb.N)、骨小梁间隙(Trabecularspacing,Tb.Sp)、结构模型指数(StructureModelIndex,SMI)。结果用本方法可以获得了清晰的骨小梁三维结构图,图像空间解析度10μm×10μm×10μm。分析结果表明,样本的上半部分与下半部分相比,骨小梁的BV/TV、BS/BV、Tb.Th、Tb.N和Tb.Sp、SMI之间存在差异(P<0.05),样本的上半部分结构致密,BV/TV较大,而Tb.Sp较小(P<0.05),小梁结构也表现为板状模型。结论距离股骨头上关节面的深度不同,股骨头的空间指标也随之出现不同的变化。     

股骨颈骨折病人的股骨头样本结构的Micro-CT评估

[目的]利用Micro-CT（Micro-computed Tomography）对正常人和老年股骨颈骨折病人的股骨头松质骨样本进行三维评价和比较。[方法]对6位正常人（正常组，27～36岁）和9位老年股骨颈骨折病人（骨折组，70～78岁）的股骨头松质骨样本进行DEXA检查，获取骨矿物密度数据。行Micro-CT扫描，得到松质骨小梁空间结构的计算机三维图形，并进行三维计量。[结果]与正常组相比，股骨颈骨折病人股骨头负重区样本的骨小梁结构在骨体积分数BV／TV、骨表面积体积比BS／TV、骨小梁厚度Tb.Th、骨小梁间隙Tb．Sp存在显著差异（P〈0．01），而骨小梁数目Tb．N、结构模型指数SMI和骨小梁模型因子Tb．Pf之间无统计学差别。骨密度检测两组没有显著性差异（P〉0．05）。[结论]股骨头松质骨的空间结构会因年龄增大而发生改变。     

茜草对大鼠股骨显微结构的影响

目的茜草对骨骼具有红染的效果,探索茜草如何影响骨骼的显微结构,是否饲喂茜草对大鼠的内脏器官具有显著的毒害作用。方法本试验选取80只1月龄大鼠,随机分为4组(分别添加茜草量为0%、5%、10%和15%入日粮中),饲喂后0.5、1、3和6个月,采取双侧股骨、内脏和血液。结果饲喂茜草6个月后,10%和15%组大鼠股骨骨干的平均厚度、骨干内径、骨干外径、骨髓腔面积、皮质骨面积、骨干总面积和股骨骨干的骨矿物质密度显著高于0%组大鼠;股骨远端骨小梁体积百分比,骨小梁厚度,连接密度,骨小梁数量和股骨远端的骨矿物质密度的水平均显著高于0%组大鼠,而股骨远端的骨小梁分离度和结构模型指数显著低于0%组大鼠。但是饲喂茜草6个月后,15%组的大鼠血液中尿素氮和肌酐的含量与0%组大鼠之间差异显著。结论饲喂10%茜草对大鼠无毒性影响,并能促进大鼠的骨骼长度和骨的显微结构,为以后茜草的合理应用提供了实验基础。     

骨质疏松症松质骨连接性参数改变与计算机辅助测量

目的 松质骨连接性参数主要指小梁骨的节点数和游离末端数,是反映松质骨显微构筑的重要参数,而松质骨的构筑情况可直接影响其力学性能。本研究旨在观察骨质疏松症小梁骨连接性参数的改变,并介绍一种计算机辅助测量方法。方法 对老年人和青年人股骨头负重区与非负重区、卵巢切除后７周大鼠椎体骨以及采用重组人生长激素治疗后的椎体标本,进行节点数和游离末端数的测量。并发展了小梁骨节九和游离末端数的计算机图像自动分析系统     

骨水泥振动器的运用对骨水泥-骨界面微嵌合的影响

目的 评价骨水泥振动器对提高骨水泥-骨界面的整合效果及临床意义. 方法 取新鲜成猪股骨16根,随机分成两组,实验组(A组)与对照组(B组)模型各8根.猪股骨髓腔内应用骨水泥振动器进行骨水泥灌注后(对照组灌注骨水泥不经振动),对每组实验模型进行硬组织切片,每根股骨模型等距选取3个层面,HE染色后在体视显微镜下观察,经电脑Motic Med 6.0数码医学图像分析系统分析测量骨水泥渗透入松质骨腔的厚度,记为渗透厚度,将所得数值进行统计学分析,对比振动组与对照组的骨水泥灌注效果. 结果 体视显微镜下显示实验组骨水泥与骨小梁之间结合紧密,骨水泥在松质骨腔内充填均匀一致,骨水泥与骨小梁之间的结合紧密.对照组骨水泥向松质骨腔内渗透欠佳,在松质骨腔内充填不均匀.结果显示实验组骨水泥渗透厚度高于对照组,差异均具有统计学意义(P＜0.05). 结论 骨水泥振动器能够使骨水泥在骨髓腔内弥散更加均匀,能够促进骨水泥向骨小梁内渗透,从而增加骨水泥与骨小梁之间的微嵌合.     

Comparison of Quantitative Cancellous Bone Connectivity Analyses at Two- and Three-Dimensional Levels in Dialysis Patients

Assessment of cancellous bone connectivity has the potential to aid in predicting fracture risk. Today, cancellous bone connectivity is generally assessed using bone sections obtained from biopsy. However, how reliably such two-dimensional (2-D) analyses visualize the 3-D properties has not been evaluated. Biopsied iliac bone samples were obtained from 47 chronic hemodialysis patients. Bone samples were observed using a microfocus X-ray computed tomography (μCT) system en bloc, and the cancellous bone microstructure was quantitatively assessed at both the 2- and 3-D levels. Cancellous bone microarchitecture was successfully reconstructed from the data obtained by the μCT system. Most of the results from node-strut analysis (NSA) revealed no statistically significant correlations between the 2- and 3-D analyses, with the exception that the number of nodes (N.Nd/TV) showed a mild but significant correlation. In contrast, the marrow space star volumes (V*m) of the 2- and 3-D analyses were highly correlated. NSA parameters including N.Nd/TV showed significant correlations with V*m at the 3-D level. In conclusion, V*m values were similar in the 2- and 3-D analyses, while most of the 2-D NSA parameters did not reflect the 3-D ones. Since V*m and most of the NSA parameters were correlated in the 3-D analyses, 2-D NSA would seem to have serious limitations for the assessment of cancellous bone microstructural properties. Further studies will thus be needed to establish appropriate methods for assessing cancellous bone connectivity in clinical practice.     

Age-related variations in the microstructure of human tibial cancellous bone.

A thorough understanding of the microstructure of cancellous bone is crucial for diagnosis, prophylaxis, and treatment of age-related skeletal diseases. Until now, little has been known about age-related variations in the microstructure of peripheral cancellous bone. This study quantified age-related changes in the three-dimensional (3D) microstructure of human tibial cancellous bone. One hundred and sixty cylindrical cancellous bone specimens were produced from 40 normal proximal tibiae from 40 donors, aged 16-85 years. These specimens were micro-computed tomography (micro-CT) scanned, and microstructural properties were determined. The specimens were then tested in compression to obtain Young's modulus. The degree of anisotropy, mean marrow space volume, and bone surface-to-volume ratio increased significantly with age. Bone volume fraction, mean trabecular volume, and bone surface density decreased significantly with age. Connectivity did not have a general relationship with age. Bone volume fraction together with anisotropy best predicted Young's modulus. Age-related changes in the microstructural properties had the same trends for both medial and lateral condyles of the tibia. The observed increase of anisotropy and constant connectivity suggest a bone remodeling mechanism that may reorient trabecular volume orientation in aging tibial cancellous bone. The aging trabeculae align more strongly to the primary direction--parallel to the tibial longitudinal loading axis.     

Quantification of age-related changes in the structure model type and trabecular thickness of human tibial cancellous bone

Structure model type and trabecular thickness are important characteristics in describing cancellous bone architecture. It has been qualitatively observed that a radical change of trabeculae from plate-like to rod-like occurs in aging, bone remodeling, and osteoporosis. Thickness of trabeculae has traditionally been measured using model-based histomorphometric methods on two-dimensional (2-D) sections. However, no quantitative study has been published based on three-dimensional (3-D) methods on the age-related changes in structure model type and trabecular thickness for human peripheral (tibial) cancellous bone. In this study, 160 human proximal tibial cancellous bone specimens from 40 normal donors, aged 16 to 85 years, were collected. These specimens were micro-computed tomography (micro-CT) scanned, then the micro-CT images were segmented using optimal thresholds. From accurate 3-D data sets, structure model type and trabecular thickness were quantified by means of novel 3-D methods. Structure model type was assessed by calculating the structure model index (SMI). The SMI was quantified based on a differential analysis of the triangulated bone surface of a structure. This technique allows quantification of structure model type, such as plate, rod objects, or mixture of plates or rods. Trabecular thickness is calculated directly from 3-D images, which is especially important for an a priori unknown or changing structure. Furthermore, 2-D trabecular thickness was also calculated based on the plate model. Our results showed that structure model type changed towards more rod-like in the elderly, and that trabecular thickness declined significantly with age. These changes become significant after 80 years of age for human tibial cancellous bone, whereas both properties seem to remain relatively unchanged between 20 and 80 years. Although a fairly close relationship was seen between 3-D trabecular thickness and 2-D trabecular thickness, real 3-D trabecular thickness was significantly underestimated using 2-D method.     

Recombinant human parathyroid hormone (1-34) [teriparatide] improves both cortical and cancellous bone structure.

Histomorphometry and microCT of 51 paired iliac crest biopsy specimens from women treated with teriparatide revealed significant increases in cancellous bone volume, cancellous bone connectivity density, cancellous bone plate-like structure, and cortical thickness, and a reduction in marrow star volume. INTRODUCTION: We studied the ability of teriparatide (rDNA origin) injection [rhPTH(1-34), TPTD] to improve both cancellous and cortical bone in a subset of women enrolled in the Fracture Prevention Trial of postmenopausal women with osteoporosis after a mean treatment time of 19 months. This is the first report of a biopsy study after treatment with teriparatide having a sufficient number of paired biopsy samples to provide quantitative structural data. METHODS: Fifty-one paired iliac crest bone biopsy specimens (placebo [n = 19], 20 microg teriparatide [n = 18], and 40 microg teriparatide [n = 14]) were analyzed using both two-dimensional (2D) histomorphometry and three-dimensional (3D) microcomputed tomography (microCT). Data for both teriparatide treatment groups were pooled for analysis. RESULTS AND CONCLUSIONS: By 2D histomorphometric analyses, teriparatide significantly increased cancellous bone volume (median percent change: teriparatide, 14%; placebo, -24%; p = 0.001) and reduced marrow star volume (teriparatide, -16%; placebo, 112%; p = 0.004). Teriparatide administration was not associated with osteomalacia or woven bone, and there were no significant changes in mineral appositional rate or wall thickness. By 3D cancellous and cortical bone structural analyses, teriparatide significantly decreased the cancellous structure model index (teriparatide, -12%; placebo, 7%; p = 0.025), increased cancellous connectivity density (teriparatide, 19%; placebo, - 14%; p = 0.034), and increased cortical thickness (teriparatide, 22%; placebo, 3%; p = 0.012). These data show that teriparatide treatment of postmenopausal women with osteoporosis significantly increased cancellous bone volume and connectivity, improved trabecular morphology with a shift toward a more plate-like structure, and increased cortical bone thickness. These changes in cancellous and cortical bone morphology should improve biomechanical competence and are consistent with the substantially reduced incidences of vertebral and nonvertebral fractures during administration of teriparatide.     

体绘制分体建模法建立人体股骨有限元模型

背景：股骨三维有限元研究建模方法有很多种,而采用体绘制分体建模方法至目前为止尚未见报道。目的：采用体绘制分体建模方法建立正常人股骨三维有限元实体模型,分析该建模方法的优越性。方法：将CT原始图像进行去噪等预处理后,建立正常人股骨三维有限元模型,模型包括皮质骨、松质骨及髓腔3部分解剖结构。再将皮质骨分为3种材料、松质骨分为6种材料,骨髓为单一材料属性分体建模,并行有限元力学分析。结果：采用体绘制分体建模方法建立的人股骨三维有限元模型包括皮质骨、松质骨及髓腔解剖结构。结论：采用体绘制分体建模比整体建模单一划分材料更接近真实情况,更符合有限元分析的要求。     

Noninvasive in vivo monitoring of bone architecture alterations in hindlimb-unloaded female rats using novel three-dimensional microcomputed tomography.

We tested a novel microcomputed tomograph designed to longitudinally and noninvasively monitor bone alterations in hindlimb-unloaded female rats at a resolution of 26 microm over a period of 3 weeks. This prototype has a potential to detect three-dimensional trabecular microarchitectural changes induced by growth and unloading. INTRODUCTION: Until now, data concerning structural changes of cancellous bone have only been available after necropsy of animals. In this study, we tested a novel microcomputed tomography (microCT) technique designed to monitor such changes repeatedly at a resolution of 26 microm with an acquisition time of about 10 minutes to map the entire proximal tibial metaphysis. MATERIALS AND METHODS: Four-month-old female Wistar rats were randomized to seven groups of 10 animals to be either tail-suspended or to act as controls. MicroCT and DXA measurements were performed at 0, 7, 14, and 23 days in suspended and control rats. One group was killed at each of these time points, and bone samples were processed for histomorphometry and ex vivo microCT. RESULTS: We verified that a good correlation was obtained between two-dimensional bone parameters evaluated in longitudinal tibial sections either by histomorphometry or microCT and microCT parameters obtained from either in vivo or ex vivo tibias. The longitudinal survey allowed earlier detection of both growth and unloading-related bone changes than the transverse survey. In controls, aging induced denser bones, reorganization of the trabecular network toward a more oriented plate-like structure, and an isotropic pattern. Unloading first inhibited cortical and cancellous bone growth and then induced bone loss characterized by fewer trabeculae, reduced connectivity density, and enhanced structure model index (SMI), revealing a lighter cancellous structure with development of rod-like characteristics. CONCLUSION: We show for the first time that this microCT prototype has a great potential to accurately, repeatedly, reliably, and rapidly investigate alterations of three-dimensional trabecular microarchitecture.     

Changes in the three-dimensional microstructure of human tibial cancellous bone in early osteoarthritis

We obtained medial and lateral subchondral cancellous bone specimens from ten human post-mortem proximal tibiae with early osteoarthritis (OA) and ten normal age- and gender-matched proximal tibiae. The specimens were scanned by micro-CT and the three-dimensional microstructural properties were quantified. Medial OA cancellous bone was significantly thicker and markedly plate-like, but lower in mechanical properties than normal bone. Similar microstructural changes were also observed for the lateral specimens from OA bone, although there had been no sign of cartilage damage. The increased trabecular thickness and density, but relatively decreased connectivity suggest a mechanism of bone remodelling in early OA as a process of filling trabecular cavities. This process leads to a progressive change of trabeculae from rod-like to plate-like, the opposite to that of normal ageing. The decreased mechanical properties of subchondral cancellous bone in OA, which are due to deterioration in architecture and density, indicate poor bone quality.     

Effects of hyaluronan on three-dimensional microarchitecture of subchondral bone tissues in guinea pig primary osteoarthrosis

Hyaluronan (HA) has received increasing interest as a potential agent in therapeutic intervention in osteoarthrosis (OA). HA has been shown to reduce arthritic lesions in experimental animal models of articular cartilage injury. This study was to investigate the effects of high molecular weight HA intra-articular injection on subchondral bone tissues. Fifty-six male guinea pigs were randomly divided into 5 groups. During the initial 2.5-month period, three groups received intra-articular injection of HA 0.4 mg/kg/week for 5 weeks in both knee joints. Two control groups received vehicle. After 2.5 months, one HA group and one control group were sacrificed. The remaining 3 groups (5.5-month groups) were left for an additional 3 months before sacrifice during which time one HA group received additional 5 weeks injections, one HA group received no more injections, and the control group received vehicle. The left tibiae were harvested and micro-CT scanned to quantify three-dimensional microarchitecture of subchondral bone plate, cancellous bone and cortical bone, followed by mechanical testing and collagen and mineral determinations. All HA-treated groups had almost normal cartilage, whereas the control groups had typical OA-related cartilage degradation. In the 2.5-month group, HA resulted in significantly decreased subchondral plate volume fraction and thickness and HA-treated cancellous bone had significantly lower bone volume fraction, and typical rod-like structure. After 5.5 months, these changes were more pronounced, with an additional marked decrease in connectivity and bone surface density. HA-treated cortical bone had significantly greater volume fraction at both observation times. HA groups had greater bone mineral concentration and reduced collagen to mineral ratio with similar mechanical properties of cancellous bone but less stiff cortical bone. The effects of HA on cartilage and subchondral bone were maintained when treatment was discontinued. In summary, HA effectively protects against cartilage degeneration, decreases subchondral bone density and thickness, changes trabecular structure toward rod-like, so that subchondral bone becomes more compliant and thereby reduces cartilage stress during impact loading. HA preserved cancellous bone mechanical properties by increasing bone mineralization. Early HA administration is effective for intervention of OA initiation and progression, and short-term early HA treatment is sufficient to maintain treatment effects.