老年女性股骨颈皮质哈氏系统的破骨细胞性骨吸收的扫描电镜观察

７例老年女性骨质疏松患者，因骨颈囊内骨折而行人工股骨头置换手术时，取骨折部位的股骨颈皮质骨，修成横切面标本。在扫描电镜下观察。发现皮质骨中，圆形、卵圆形的哈氏管经历着扩大的变化。扩大哈氏管的壁面呈两多吸收陷窝，反映破骨细胞性吸收，哈氏管的骨吸收及扩大，最先发生在皮质骨的内侧部分，并形成巨大的、圆形和卵圆形的空隙，从而使内侧部分变疏松。以后，骨吸收及扩大又相继发生在皮质骨的中间部分及外侧部分的哈低管     

宿主骨髓对同种异体皮质骨爬行替代过程中VEGF表达的影响

目的:研究宿主骨髓对VEGF表达的影响,揭示异体皮质骨移植后的愈合机理.方法:新西兰大白兔72只,24只制备深冻异体骨,48只移植异体骨术后1、2、4、6、8、12周取材,对比双侧VEGF表达的差异.结果:移植后4周,实验侧扩大的哈佛氏管强阳性表达;6～8周,扩大的哈佛氏管内生长活跃的细胞和新的管状结构等强阳性表达;8～12周,吸收骨陷窝内生长活跃的骨细胞强阳性表达.对照侧6周开始出现少量弱阳性表达的扩大哈佛氏管.双侧对比,阳性表达骨细胞计数均差异性显著.结论:(1)异体皮质骨内部的血运来源与外周不同;(2)宿主骨髓通过哈佛氏管,对异体皮质骨内部的血运重建和成骨活动中起着重要作用.     

宿主骨髓对同种异体皮质骨爬行替代过程中VEGF表达的影响

目的：研究宿主骨髓对VEGF表达的影响，揭示异体皮质骨移植后的愈合机理。方法：新西兰大白兔72只，24只制备深冻异体骨，48只移植异体骨术后1、2、4、6、8、12周取材，对比双侧VEGF表达的差异。结果：移植后4周，实验侧扩大的哈佛氏管强阳性表达；6～8周，扩大的哈佛氏管内生长活跃的细胞和新的管状结构等强阳性表达；8～12周，吸收骨陷窝内生长活跃的骨细胞强阳性表达。对照侧6周开始出现少量弱阳性表达的扩大哈佛氏管。双侧对比，阳性表达骨细胞计数均差异性显著：结论：(1)异体皮质骨内部的血运来源与外周不同；(2)宿主骨髓通过哈佛氏管，对异体皮质骨内部的血运重建和成骨活动中起着重要作用。     

转化生长因子β不同给药方式对骨折愈合的影响

目的探讨不同给药方式给予外源性TGF-β对骨折愈合的促进作用.方法采用兔右尺骨骨折模型,不同给药方式下在骨折区给予TGF-β,观察骨折愈合后生物力学、骨痂面积、皮质骨厚度和哈佛氏管直径的变化.结果给予TGF-β各组的骨痂面积和最大抗弯强度明显增加,以缓释系统给予法治疗后的作用最强,对极限应力、刚度、极限负荷时能量吸收、皮质骨厚度和哈佛氏管直径则没有影响.结论外源性TGF-β对骨折愈合有一定促进作用,不同给药方式给予TGF-β,对骨折愈合作用的效果不同,以缓释系统法给予TGF-β的效果较强.     

转化生长因子β不同给药方式对骨折愈合的影响

目的：探讨不同给药方式给予外源性TGF-β对骨折愈合的促进作用。方法：采用兔右尺骨骨折模型。不同给药方式下在骨折区给予TGF-β，观察骨折愈合后生物力学，骨痂面积，皮质骨厚度和哈佛氏管直径的变化。结果：给予TGF-β各组的骨痂面积和最大抗弯强度明显增加，以缓释系统给予法治疗后的作用最强，对极限应力，刚度，极限负荷时能量吸收，皮质骨厚度和哈佛氏管直径则没有影响。结论：外源性TGF-β对骨折愈合有一定促进作用，不同给药方式给予TGF-β，对骨折愈合作用的效果不同，以缓释系统法给予TGF-β的效果较强。     

动力髋螺钉固定股骨转子间骨折的有限元分析

目的研究后内侧骨折块对股骨转子间骨折动力髋螺钉(DHS)固定后的生物力学影响。方法利用股骨CT数据建立一组股骨近端的三维有限元模型,在此基础上制作股骨转子间骨折累及小转子和内侧骨皮质的骨折模型,对骨折模型进行DHS固定,并对DHS固定模型进行有限元分析。结果股骨转子间骨折累及单纯小转子骨折后,股骨内侧皮质应力和外侧DHS钢板所承受的应力大小无明显变化。当累及1/2内侧皮质时,内侧应力升高约28%,外侧DHS钢板所承受的应力升高约9%;当内侧皮质完全累及时,前内侧皮质的交界处应力升高约125%,外侧DHS钢板所承受的应力升高约96%。结论股骨转子间骨折伴单纯小转子骨折可以不予固定;而当内侧皮质累及时,无论是累及1/2还是累及全部内侧骨皮质,均需复位固定后内侧骨皮质。     

基于骨皮质形态特点选择胫骨下段骨折钢板固定位置

目的探讨骨皮质形态特点对胫骨中下段骨折钢板内固定位置的作用。方法手术治疗46例不涉及关节面的胫骨下段骨折,其中胫骨内侧解剖型钢板内固定23例（内侧固定组）,胫骨外侧解剖型钢板内固定23例（外侧固定组）。比较两种术式的并发症发生情况。进行临床和X线片检查随访,同时CT重建患侧胫骨骨皮质,利用Photoshop 7.0软件计算骨皮质面积。结果患者均获随访,时间12～36个月。内侧固定组出现骨折迟缓愈合1例,无骨折移位;外侧固定组出现骨折迟缓愈合6例,骨折移位2例。与外侧固定组比较,内侧固定组骨折迟缓愈合率低（P〈0.05）。胫骨中远段骨皮质面积比较,内侧骨皮质面积较外侧骨皮质大（P〈0.01）,前侧骨皮质面积较后侧骨皮质大（P〈0.01）。结论对于闭合不涉及关节面的胫骨下段骨折,内侧固定组具有更加符合天然骨生物力学条件、并发症少等特点,应优先考虑使用。     

有限元法分析后内侧骨折对近端股骨的力学影响

[目的]研究后内侧骨折对近端股骨的生物力学影响。[方法]利用CT扫描图像建立高度仿真的完整近端股骨的三维有限元模型,并在此基础上建立累及小粗隆和内侧皮质的后内侧骨折模型,并对模型进行有限元分析。[结果]后内侧骨折后股骨最大应力出现在骨折缺损的前内侧。单独小粗隆骨折后股骨颈上下、内外侧皮质应力无明显变化;骨折累及1/2内侧皮质后,内侧皮质最大等效应力显著升高约47%,外侧皮质应力升高约12%;内侧皮质完全累及时,内侧皮质应力升高约247%,外侧升高约66%。[结论]不同大小的后内侧骨折块对近端股骨的应力大小及分布影响不同。从力学角度考虑,用动力髋螺钉治疗粗隆间骨折时,可根据后内侧骨折块大小作适当处理。     

肱骨髁上楔形截骨矫正外伤性肘内翻

目的　寻找简易手术及内固定方法矫正外伤性肘内翻。方法　采用外侧直切口 ,截骨之前将 2根克氏针经外侧髁插入至远侧截骨线 ;采用楔形不完全截骨 ,保留内侧骨皮质 ,沿截骨线钻数个小孔 ,然后去除三角形骨块 ,用手法折断内侧骨皮质 ;在外翻位加压 ,同时前臂旋后和肘关节屈曲位直到角度满意后将远端克氏针送入近侧截骨线至内侧骨皮质。术后用石膏托外固定患肢于屈肘 90°位l～l 5个月。结果　 6 4例患者畸形均矫正并有平均 4 2°提携角。无神经损伤或感染等并发症。随访 1～ 5年 (平均 3 6年 ) ,无一例再次复发。结论　该技术操作简单 ,损伤小 ,手术并发症少 ,效果好     

大剂量因卡膦酸钠的长期应用对骨细胞密度的影响

目的 评估大剂量因卡膦酸钠的长期应用对骨细胞密度影响.方法 30只猎犬,犬龄1年,按体重随机分成3组(每组雌雄各5只):分别每天给予口服因卡膦酸钠低剂量组0.3 mg·kg-1和高剂量组0.6 mg·kg-1,对照组犬给予口服乳糖12 mg·kg-1·d-1,所有犬持续给药3年.处死前进行四环素双标,处死后取左侧第九肋骨进行组织形态计测和骨皮质表面骨细胞密度测量.结果 组织形态计测表明高剂量双膦酸盐组的骨激活频率明显低于对照组,降低了86.5 %,而低剂量双膦酸盐组的骨激活频率与对照组无统计学差异.低剂量组和高剂量组的骨细胞密度都明显高于对照组,分别增加了31.8%和56.3%.结论 双膦酸盐长期应用可抑制骨转换,增加骨皮质表面的骨细胞密度.     

Investigating histomorphometric relationships at the human femoral midshaft in a biomechanical context

Cortical bone histomorphometry utilised in human and animal bone biology studies has demonstrated that osteon densities and their geometric properties may be in a relationship with biomechanical load application. Further research is required to investigate mutual links between bone histological variables to elucidate their usefulness in future biomechanical studies. Here, a series of correlations exploring bone biology relationships at the human midshaft femur were performed using a large sample. Mean intact, fragmentary and total osteon population densities, Haversian canal diameter and area, osteon area, as well as osteocyte lacunae density were measured along the sub-periosteal cortex in sections removed from the posterior midshaft aspect of modern human male (n = 233) and female (n = 217) femora (total n = 450). Parametric and non-parametric correlations between the histology variables were sought in the entire sample, as well as within age and sex sub-groups. Several significant positive and negative correlations explaining a large proportion of data variation were found. Haversian canal area, diameter, and osteon area were positively correlated. As the density of osteocyte lacunae increased, Haversian canals and osteons became smaller. As osteons increased in density, so did osteocyte lacunae, but Haversian canal and osteon area became smaller. Results were consistent across age and sex groups. Findings suggest that an increased rate of bone remodelling is associated with a decrease in geometrical properties of osteons. An increased density of osteocyte lacunae and osteons indicates the involvement of bone maintenance cells in remodelling potentially induced by mechanical stimuli. Future histomorphometry studies will benefit from examining multiple bone histology variables due to many mutual bone biology relationships that exist at the human midshaft femur.     

Age changes in bone mineralization,cortical thickness,and Haversian canal area

Summary Age-related changes in femoral cortical bone were quantified in an age-graded series of human cadavers. Variables included in this study were cortical thickness, bone mineral content, cortical bone density, summed Haversian canal area, Haversian canal number, and mean Haversian canal area. Females showed significant (P<0.05) decreases in cortical thickness, bone mineral content, and cortical bone density when plotted against age. Males exhibited slight nonsignificant declines for cortical thickness, bone mineral content, and cortical bone density. Both males and females exhibited significant (P<0.05) age-related increases in summed Haversian canal area values and Haversian canal number. Females as a group were found to exhibit significantly (P<0.05) larger mean Haversian canal area values compared with males, but the male group exhibited more Haversian canals per unit area of cortical bone compared with females. Intercorrelations between the bone mineral index and summed Haversian canal area and between cortical bone density and summed Haversian canal area define the role of increasing Haversian canal number and mean canal size per unit area of cortical bone as a factor in the reduction of bone mass as a function of age. Partial correlations between the bone mass variables and the variables assessing Haversian canal size and number further support this argument.     

Osteocyte recruitment declines as the osteon fills in: interacting effects of osteocytic sclerostin and previous hip fracture on the size of cortical canals in the femoral neck

There is little information on the distribution of osteocytes within the individual cortical osteon, but using direct 3-D imaging in a single subject, Hannah et al. found a gradient with a two-fold higher density of cells adjacent to the cement line compared to near the canal. Since a limiting factor for bone formation might be the availability of osteoblasts due to their recruitment as osteocytes, we studied distributions of osteonal osteocytes in frozen sections of the femoral neck cortex. Osteocytes were stained with an anti-sclerostin antibody and counter-stained with toluidine blue. Adjacent sections were stained for alkaline phosphatase (ALP). Each osteonal osteocyte was categorised as being sclerostin-positive (scl+) or negative (scl-). ImageJ was used to measure the perimeter and area of each osteon and canal, while special purpose routines were used to measure the minimum distances of each osteocyte from the cement line and the canal. Canal area was strongly correlated with osteon area. Osteocytes were most dense close to the cement line; and their areal density within the matrix declined up to three-fold between the cement line and the canal, depending on osteon diameter. Large and small osteons had similar densities of osteocytes close to the cement line, but fractured neck of femur cases had significantly lower densities of osteocytes close to the canal. Higher osteocyte density close to the canal was associated with ALP expression. It is concluded that entombment of osteocytes newly drawn from the osteoblast pool into the mineralising matrix is independent of preceding bone resorption depth. As osteonal infilling proceeds, osteocyte formation declines more rapidly than matrix formation, leading to a progressive reduction in osteocyte density. A shrinking supply of precursor osteoblasts due to previous osteocyte recruitment, apoptosis, or both could produce this effect. In a statistically significant contrast, sclerostin negative osteocytes adjacent to the canal had the expected effect of reducing canal size in controls but this was not seen in hip fracture. This demonstrated the failure of osteonal osteoblasts to sustain bone formation through a complete remodelling cycle in osteoporosis, perhaps due to insufficient osteoblasts remaining capable of mineralized matrix formation. The failure of osteocytic sclerostin suppression to associate with bone formation in these osteons might alternatively be explained by downstream interference with sclerostin's effect on wnt signalling.     

Anatomy of the Intracortical Canal System: Scanning Electron Microscopy Study in Rabbit Femur

The current model of compact bone is that of a system of longitudinal (Haversian) canals connected by transverse (Volkmann’s) canals. Models based on histology or microcomputed tomography lack the morphologic detail and sense of temporal development provided by direct observation. Using direct scanning electron microscopy observation, we studied the bone surface and structure of the intracortical canal system in paired fractured surfaces in rabbit femurs, examining density of canal openings on periosteal and endosteal surfaces, internal network nodes and canal sizes, and collagen lining of the inner canal system. The blood supply of the diaphyseal compact bone entered the cortex through the canal openings on the endosteal and periosteal surfaces, with different morphologic features in the midshaft and distal shaft; their density was higher on endosteal than on periosteal surfaces in the midshaft but with no major differences among subregions. The circumference measurements along Haversian canals documented a steady reduction behind the head of the cutting cone but rather random variations as the distance from the head increased. These observations suggested discontinuous development and variable lamellar apposition rate of osteons in different segments of their trajectory. The frequent branching and types of network nodes suggested substantial osteonal plasticity and supported the model of a network organization. The collagen fibers of the canal wall were organized in intertwined, longitudinally oriented bundles with 0.1- to 0.5-μm holes connecting the canal lumen with the osteocyte canalicular system. One or more of the authors (UEP, DQ) have received funding from the University of Brescia and University of Insubria. Each author certifies that his or her institution has approved the animal protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research. This work was performed at Spedali Civili di Brescia and at Dipartimento di Morfologia Umana dell'Università dell'Insubria.     

Osteocyte lacunar size-lamellar thickness relationships in human secondary osteons

Previous investigations carried out in our laboratory on secondary osteons have shown that osteocyte lacunae decrease in size from the cement line towards the Haversian canal, and lamellar bone is made up of alternating nonosteocytic dense lamellae and osteocytic loose lamellae, all having an interwoven texture of collagen fibers. Such alternation of acellular and cellular lamellae was hypothesized to depend on osteocyte recruitment from osteogenic laminae in successive layers, assuming that the loose lamellae form because of alignment and fusion of the periosteocytic loosely arranged collagen fibers. In order to discover whether a correlation really exists between osteocyte lacunar size and lamellar thickness, as would be expected if the above-mentioned hypothesis were true, both these parameters were measured in completed secondary osteons in relation to their distance from the Haversian canal. The size of osteocyte lacunae was measured under light microscopy on undecalcified dry-mounted ground section of tibial compact bone from three adult males and three adult females not affected by metabolic bone disease. The measurement of the thickness of bony lamellae was carried out on the same samples under scanning electron microscopy. Statistical analyses of the results showed that the decrease in size of osteocytic lacunae from the outer to the inner osteonal wall is paralleled by a decrease in thickness of osteocytic loose lamellae. The fact that acellular dense lamellae do not follow such a decremental pattern, but remain of the same thickness throughout the osteonic wall, corroborates Marotti's view that the formation of lamellar bone depends on the orderly distribution of the osteocytes in alternating planes. The topographical distribution of osteocyte lacunar size and lamellar thickness is briefly discussed in relation to secondary osteon mechanical function.     

Dependence of bone yield (volume of bone formed per unit of cement surface area) on resorption cavity size during osteonal remodeling in human rib: implications for osteoblast function and the pathogenesis of age‐related bone loss

It is both a necessary and a sufficient condition for bone to be lost with age at any surface location that during remodeling the replacement of resorbed bone is incomplete. In both the ilium and the rib, the degree of such focal imbalance is smaller on the intracortical than on the endocortical or cancellous surfaces that are adjacent to bone marrow. The reason for this difference is unknown. To further examine this question, we measured various geometric variables in 1263 osteons in rib cross sections from 65 persons, including both sexes and age ranges 20 to 30 years and 60 to 70 years (four groups). Haversian canal (HC) area did not differ significantly between sexes or age groups. Percent osteonal refilling was close to 95% in all groups and did not differ between sexes but fell slightly with age. There was a very highly significant linear relationship between osteon bone area and (osteon area + HC area) in all groups, with coefficients of determination (r²) greater than 0.98. The regression slopes declined slightly with age in women but not in men. There was a very highly significant quadratic relationship between osteon bone area and osteon perimeter in all groups, with r² values greater than 0.97. The ratio osteon bone area:osteon perimeter, an index of bone yield—the volume of bone deposited on each unit area of cement surface—was strongly related to osteon area and did not differ between sexes but was slightly less in the older groups. We conclude the following: (1) The high efficiency of intracortical remodeling in the rib is confirmed, with only trivial effects of age. (2) For HC area to be maintained within narrow limits and bone balance preserved, either initial osteoblast density or osteoblast capacity (the two determinants of bone yield) or, most likely, both must increase progressively with the size of the resorption cavity, suggesting that osteoblast recruitment (relative to available surface) and osteoblast lifespan increase with the volume of bone resorbed. (3) Intracortical remodeling in the rib is more efficient than marrow‐adjacent remodeling at any site, possibly because of the different relationships to the circulation. In osteonal remodeling, all molecules released from resorbed bone must travel past the sites of osteoblast recruitment and operation, but in hemiosteonal remodeling, some molecules may not be subject to this constraint. (4) If marrow‐adjacent remodeling became as efficient as rib intracortical remodeling, age‐related bone loss would cease to be an important medical problem. © 2010 American Society for Bone and Mineral Research     

Osteocyte morphology in human tibiae of different bone pathologies with different bone mineral density — Is there a role for mechanosensing?

Matrix strains due to external loading are different in bones of different pathologies with different bone mineral density (BMD), and are likely sensed by the osteocytes, the putative bone mechanosensors. The mechanosensitivity of osteocytes appears to be strongly influenced by their morphology. In this study, we explored the possibility that osteocyte morphology might play a role in various bone pathologies with different BMD.Confocal laser scanning microscopy and nano-CT were used to quantitatively determine 3D morphology and alignment of osteocytes and osteocyte lacunae in human proximal tibial bone with relatively low (osteopenic), medium (osteoarthritic), and high (osteopetrotic) BMD.Osteopenic osteocytes were relatively large and round (lengths 8.9:15.6:13.4 μm), osteopetrotic osteocytes were small and discoid shaped (lengths 5.5:11.1:10.8 μm), and osteoarthritic osteocytes were large and elongated (lengths 8.4:17.3:12.2 μm). Osteopenic osteocyte lacunae showed 3.5 fold larger volume and 2.2 fold larger surface area than osteoarthritic lacunae, whereas osteopetrotic lacunae were 1.9 fold larger and showed 1.5 fold larger surface area than osteoarthritic lacunae. Osteopetrotic osteocyte lacunae had lower alignment than osteopenic and osteoarthritic lacunae as indicated by their lower degree of anisotropy.The differences in 3D morphology of osteocytes and their lacunae in long bones of different pathologies with different BMD might reflect an adaptation to matrix strain due to different external loading conditions. Moreover, since direct mechanosensing of matrix strain likely occurs by the cell bodies, the differences in osteocyte morphology and their lacunae might indicate differences in osteocyte mechanosensitivity. The exact relationship between osteocyte morphology and bone architecture, however, is complex and deserves further study.     

The importance of murine cortical bone microstructure for microcrack initiation and propagation

In order to better understand bone postyield behavior and consequently bone failure behavior, this study aimed first to investigate cortical bone microstructure and second, to relate cortical bone microstructure to microdamage initiation and propagation in C57BL/6 (B6) and C3H/He (C3H) mice; two murine inbred strains known for their differences in bone phenotype. Murine femora of B6 and C3H were loaded axially under compression in a stepwise manner. For each loading step, 3D data sets at a nominal resolution of 700 nm were acquired by means of synchrotron radiation-based computed tomography. Cortical bone microstructure was divided into three phases: the canal network, the osteocyte lacunar system, and microdamage. Canal volume density and canal unit volume both correlated highly to crack number density (canal volume density: R(2)=0.64, p<0.005 and canal unit volume: R(2)=0.75, p<0.001). Moreover, the large canal units in C3H bone were responsible for more microdamage accumulation compared to B6 bones. This more pronounced microdamage accumulation due to large intracortical bone voids, which eventually leads to a fatal macrocrack (fracture), represents a potential contributing factor to the higher incidence of bone fractures in the elderly.     

Effect of microstructure on the mechanical properties of Haversian cortical bone

The mechanical properties of cortical bone have been extensively studied at the macrostructural scale. However, knowledge of the macroscopic mechanical properties is not sufficient to predict local phenomena, such as damage or bone remodeling, both of which are dependent on local mechanical behavior. The objective of this study is to quantify the mechanical properties of cortical bone at several length scales, with emphasis on the microstructure of Haversian systems. Samples of mature bovine cortical bone, with a Haversian microstructure, were obtained from the posterior area of the mid-femoral diaphysis. A nanoindentation technique was used to measure the local Young's modulus. The distribution of the bone mineral content was obtained by backscattered electron imaging using a scanning electron microscope. A novel compression device employing microextensometry techniques was developed to quantify local strains. Digital image correlation was performed on the microstructure imaged by optical microscopy during compression tests. This study demonstrated that the local Young's modulus and strain were heterogeneous at the scale of an osteon. For both properties, the ratio between the maximum and minimum values was approximately two. The local Young's modulus and bone-mineral content were reasonably correlated (r2 = 0.75; P < 0.0001), but this was not the case for the distribution of local strains versus bone mineral content (r2 = 0.395; P < 0.0001). Hence, local strains cannot be described simply in terms of the bone mineral content, as the Haversian canal and osteonal microstructure have a major influence on these properties. In conclusion, the microstructure must be considered in evaluating the local strain and stress fields of cortical bone.     

Rib cage asymmetry in idiopathic scoliosis

Seventy-one patients attending a scoliosis clinic and 10 control subjects were studied by a stereoradiographic three-dimensional reconstruction of the spine and rib cage. The symmetry of each rib pair (at each anatomic level) was described by measurements of rib arc length, chord length, enclosed area, maximum curvature, and frontal and lateral angulations. Patients were divided into four groups: 19 with a single right thoracic curve, 15 with a single left lumbar or thoracolumbar curve, 22 with double curves, and 15 with a curve with less than 10 degrees Cobb angle. In the control group and the group with minimal scoliosis, there was no statistically significant rib asymmetry. Among the patients with scoliosis, 11 of 19 patients with right single thoracic curves had rib arc lengths greater on the right side at the curve apex, and nine of 15 patients with left lumbar scoliosis had longer ribs on the left side in the corresponding region of the thoracic spine. Eleven of 22 patients with double curves had symmetrical rib lengths (within +/- 3%), the other 11 had ribs longer on the left. These proportions should not have occurred by chance (p less than 0.001). The mean rib length difference in patients with single thoracic curves was 1.39% (right longer than left), in single lumbar curves it was 3.57% (left longer than right), and in double curves 3.18% (left longer than right). These differences between the groups of patients and control subjects were statistically significant (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)