Relationships between shape and size of the osteoblasts and the accretion rate of trabecular bone surfaces

Summary The structure of the osteoblastic layer on trabecular bone surfaces showing different accretion rates was examined. Volume and secretory surface of the cells and thickness of the underlying osteoid border were measured within serial sections. Shape, size and arrangement of osteoblasts varied greatly on the different trabeculae examined, but were relatively homogeneous over each surface. A correlation was found between the volume-secretory surface ratio (i.e. the relative amount of protoplasmatic volume involved in osteoid production) and the thickness of the underlying osteoid seam measured separately for each osteoblast.Research supported by a C.N.R. grant.     

The postnatal development of form and orientation of the lumbar intervertebral joint surfaces

Summary The mechanisms involved in the postnatal development of the lumbar intervertebral joint surface form and orientation in the transversal plane are described. They are summarized in Fig. 8. Some important characteristics of the adult joints are found already in the newborn infant. The process of form change, occurring mainly after birth, begins before birth at full term in the low segments, and occasionally also in the high segments. Thus, important traits of the postnatal development are initiated before birth. No qualitative or evident quantitative change in the development, attributable to the development of the lordosis or to the erect posture being assumed, has been demonstrated in this study.

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Zusammenfassung Es wird die postnatale Entwicklung der Form und Orientierung der lumbalen Intervertebralgelenkflächen in der Transversalebene beschrieben. Die Mechanismen sind in Fig. 8 zusammengefaßt. Einige wichtige Merkmale des adulten Gelenks sind schon beim neugeborenen Kind vorhanden. Der Prozeß des Formwechsels, der hauptsächlich nach der Geburt auftritt, beginnt vor der Geburt in den unteren Segmenten und manchmal auch in den oberen. Also zeigen sich die wichtigsten Merkmale der postnatalen Entwicklung vor der Geburt. In dieser Studie wurde kein qualitativer oder augenfälliger quantitativer Einfluß in der Gelenkentwicklung beobachtet, den man auf die Entwicklung der Lordose oder der aufrechten Stellung zurückführen kann.

     

The three-dimensional microstructure of the trabecular bone in the mandible

This study investigated the three dimensional (3D) trabecular microstructure of the alveolar and basal bone in the mandible using micro-CT and compared the morphometric values of the different sites. Ten specimens were prepared and scanned using a micro-CT system. Both the alveolar and basal trabecular bone of the premolar region in the mandible were measured for the structural analysis. Cross-sectional 1024×1024 pixel images were created. From the two-dimensional (2D) images produced, 3D structural images were reconstructed. After scanning the specimen, the volumes of interest (VOI) of the alveolar and basal bone regions were selected from the 3D reconstruction images, and the structural parameters such as bone volume fraction, bone surface density, trabecular thickness, trabecular separation, trabecular number and structural model index were analyzed. The trabecular structure showed a marked variation within the sites of the specimen, especially in the basal trabecular bone inferior to the mandibular canal. In both the alveolar and basal bone regions, a mixture of both plate-like and rod-like structures was observed. The alveolar region showed a more compact, plate-type trabecular structure than the basal regions. In parametric comparison with the basal bone, the alveolar bone generally had a higher bone volume fraction, bone trabecular thickness and trabecular number, and lower bone surface density, trabecular separation and structural model index. The alveolar bone consisted of a compact bone structure with a large amount of thick plate-type trabecular bone, which was effectively resistant to the masticatory forces. As the measurements were made closer to the basal bone, a loose structure was observed with lower bone volume and fewer, thin, rod-like trabeculae.     

Mechanical and morphological variation of the human lumbar vertebral cortical and trabecular bone.

The nanoindentation technique was used to characterize the variation in the elastic modulus and hardness of human lumbar vertebral cortical and trabecular bone. The elastic modulus (and in most cases, the hardness as well) of axially aligned trabeculae cut in the transverse direction was significantly greater than in other orientations of vertebral cortical and trabecular bone. In all cases, the elastic modulus and hardness of bone in the load-bearing direction was greater than in corresponding bone types cut in the other directions. Scanning electron micrographs of cortical shell revealed the Haversian-like canal systems expected in secondary cortical bone, but it was difficult to differentiate by morphology cortical from trabecular bone in the human lumbar vertebrae.     

Respective roles of organic and mineral components of human cortical bone matrix in micromechanical behavior: an instrumented indentation study

Bone is a multiscale composite material made of both a type I collagen matrix and a poorly crystalline apatite mineral phase. Due to remodeling activity, cortical bone is made of Bone Structural Units (BSUs) called osteons. Since osteon represents a fundamental level of structural hierarchy, it is important to investigate the relationship between mechanical behavior and tissue composition at this scale for a better understanding of the mechanisms of bone fragility. The aim of this study is to analyze the links between ultrastructural properties and the mechanical behavior of bone tissue at the scale of osteon.Iliac bone biopsies were taken from untreated postmenopausal osteoporotic women, embedded, sectioned and microradiographed to assess the degree of mineralization of bone (DMB). On each section, BSUs of known DMB were indented with relatively high load (∼500 mN) to determine local elastic modulus (E), contact hardness (H_c) and true hardness (H) of several bone lamellae. Crystallinity and collagen maturity were measured by Fourier Transform InfraRed Microspectroscopy (FTIRM) on the same BSUs. Inter-relationships between mechanical properties and ultrastructural components were analyzed using multiple regression analysis.This study showed that elastic deformation was only explained by DMB whereas plastic deformation was more correlated with collagen maturity. Contact hardness, reflecting both elastic and plastic behaviors, was correlated with both DMB and collagen maturity. No relationship was found between crystallinity and mechanical properties at the osteon level.     

股骨近端主张力骨小梁生物力学特性

目的 研究股骨近端主张力骨小梁的生物力学性能,为解释股骨颈骨折后股骨头坏死的发生原因提供实验依据.方法 取8个正常国人(45 ～60岁)尸体股骨,排除畸形、骨折等病变.将近端主张力骨小梁系统从外侧到内侧分成3个区,在每个区内沿主张力小梁方向及与其垂直方向切取骨小梁试件,并分别在EnduraTEC ELF3200生物力学...     

健康国人颈椎和腰椎体积骨密度的定量CT研究

目的 探讨国人健康成人颈椎和腰椎体积骨密度值(vBMD)分布情况。方法 采用横断面研究方法。2014年12月—2016年1月北京积水潭医院招募770名健康志愿者,其中男329名,女441名,年龄21～59岁。志愿者按年龄分为4组:A组(21～30岁)142人,B组(31～40岁)262人,C组(41～50岁)263人,D组(51～60岁)103人。采用日本TOSHIBA 128排CT机对志愿者行颈椎和腰椎定量CT扫描,并使用Mindways骨密度测量软件测量C₂～C₇、L₂～L₄椎体的vBMD值。采用单因素方差分析分别比较颈、腰椎中vBMD在不同性别、年龄组、节段的分布情况,男性、女性颈腰椎间各椎体vBMD的相关性采用Pearson相关分析。结果 男性志愿者C₂～C₇和L₂～L₄椎体vBMD分别为(288.40±60.63)、(275.71±56.33)、(283.91±59.62)、(278.95±53.76)、(253.38±49.99)、(217.94±44.96)和(151.64±31.74)、(145.22±31.77)、(147.16±35.81)mg/cm³,女性志愿者分别为(329.24±74.34)、(313.88±67.86)、(328.54±73.40)、(323.22±72.53)、(286.44±66.36)、(251.53±58.63)和(168.50±37.10)、(160.78±37.00)、(162.81±37.10)mg/cm³。无论男性还是女性,颈椎及腰椎的体积骨密度值均随着年龄增长而逐渐下降,差异均有统计学意义(P值均＜0.05)。男性志愿者同一年龄组内比较:C₂～C₇不同椎体的vBMD均呈下降趋势,差异均有统计学意义(P值均＜0.05);而L₂～L₄不同椎体的vBMD差异均无统计学意义(P值均＞0.05)。女性志愿者同一年龄组内比较:C₂～C₇不同椎体的vBMD均呈下降趋势,差异均有统计学意义(P值均＜0.05);D组L₂～L₄各椎体的vBMD均呈下降趋势,差异有统计学意义(P＜0.05),其他年龄组vBMD差异均无统计学意义(P值均＞0.05)。无论是男性或女性志愿者,在任何年龄组,颈椎vBMD均＞200 mg/cm³,腰椎vBMD值均＜200 mg/cm³,颈椎vBMD值均高于腰椎(P值均＜0.01)。男性、女性颈腰椎不同椎体间vBMD值均具有显著的相关性(r_男性=0.509～0.968, r_女性=0.658～0.976, P值均＜0.01);男性中,r_颈椎间=0.667～0.928,r_腰椎间=0.850～0.968,r_{颈椎与腰椎间}=0.509～0.675;女性中,r_颈椎间=0.754～0.933,r_腰椎间=0.956～0.973,r_{颈椎与腰椎间}=0.658～0.752;颈椎间或腰椎间vBMD相关系数均高于颈腰椎之间相关系数。结论 颈椎和腰椎vBMD在不同性别、年龄、节段分布存在差异,但各椎体vBMD均存在中-强相关性。本研究结果可为临床监测骨质疏松、评估骨折风险提供参考数据。     

Star volume in bone research. A histomorphometric analysis of trabecular bone structure using vertical sections

Conventional bone histomorphometry performed on iliac crest biopsies does not generally provide unbiased stereological estimates of parameters related to bone structure due to the anisotropy of trabecular bone; this, however, can be obtained with vertical sections, which are anisotropic sections, in combination with an anisotropic test system. A practical procedure for obtaining vertical sections from bone is described. The new stereological parameter, the star volume, can provide an unbiased estimation of the absolute mean size of the marrow space and thus give an indirect estimate of the connectivity of trabecular bone structure. The marrow space star volume of vertebral bodies and iliac crest increases with age in both sexes demonstrating that the structural bone changes which occur with age is a topological one with changes in trabecular connectivity. The practical procedure including sampling efficiency for marrow space star volume is described. © 1993 Wiley-Liss, Inc.     

Scanning electron microscopy study of bone intracortical vessels using an injection and fractured surfaces technique

The intracortical canal/vessel systems of long bones are not yet completely understood in terms of their morphology and physiology, mainly because of the difficulty of injecting the small calibre vessels and cutting the calcified matrix. Here, we apply a novel method combining perfusion of the vessels and fracture of the cortical bone to enlighten the architecture of this system. The femurs of ten rabbits were perfused with a water-soluble dye (China ink) or alcoholic glycerol solution, and the fractured cortex specimens were then examined by scanning electron microscopy (SEM). The results document: (1) the fibrillar structure of the canal surfaces; (2) the perivascular environment with cellular components in different phases of incorporation within the bone matrix; (3) previously unreported filamentous structures on the outer surface of vessels, which could be interpreted as non-myelinic nerve fibres; (4) the inner organisation of the cutting cones. Although based exclusively on morphology, these observation have some relevance to increasing knowledge of bone circulation physiology in the cortical bone.     

一期后路病灶清除病椎置钉短节段内固定加椎间或关节突间植骨治疗单间隙腰椎布鲁杆菌病性脊柱炎

目的 评价一期后路病灶清除、病椎置钉短节段内固定加椎间或关节突间植骨治疗单间隙腰椎布鲁杆菌病性脊柱炎(BS)的可行性及疗效。方法 回顾性分析2015年1月—2016年1月河北北方学院附属第一医院收治的 27例BS患者的临床资料,其中男15例、女12例,年龄42～65岁。患者均为单间隙病变,累及两个椎体,其中L_1～2 1例,L_2～3 3例,L_3～4 8例,L_4～5 12 例,L₅～S₁ 3例;患者均合并不同程度神经功能损伤,术前至少经过一个疗程的规范药物治疗。均选用一期后路病灶清除、病椎置钉短节段内固定加椎间或关节突间植骨术治疗。对比手术前后Cobb角、VAS、美国脊髓损伤协会(ASIA )脊髓功能评定、红细胞沉降率(ESR)、C反应蛋白(CRP)、虎红平板凝集试验(RBPT)指标,以及X线片、CT、MRI影像学表现,结合临床预后进行临床疗效评价。结果 术后27例均获随访,随访时间12～25个月,平均18个月,无一例发生窦道形成及复发。侧凸Cobb角术前及术后3、6个月分别为14.89°±1.48°、4.00°±1.44°和4.01°±0.87°,VAS术前及术后3、6、12个月分别为(8.4±1.6)、(3.1±0.3)、(1.1±0.3)及(0.7±0.2)分,术后各时间点均较术前显著改善,差异均有统计学意义(P值均＜0.05);ASIA脊髓功能分级较术前明显好转,差异均有统计学意义(P值均＜0.01);随时间推移,术后ESR、CRP、Cobb角明显减小,术后各时间点与术前比较,差异均有统计学意义(P值均＜0.01)。RBPT术后转阴率(正常率)逐渐增高,术后3个月为48.14%,6个月为100%。临床疗效评价:术后3、6、12个月治愈率分别为59.25%(治愈16例、改善10例、无效1例)、81.48%(治愈22例、改善5例)、96.29%(治愈26例、改善1例),后一个时间点治愈率与前一个时间点比较,差异均有统计学意义(P值均＜0.05)。结论 在应用有效的药物控制前提下,一期后路病灶清除、病椎置钉短节段内固定加椎间或关节突间植骨治疗单间隙BS是可行的,其在解除疼痛、稳定脊柱及恢复神经功能等方面具有较好的临床疗效。     

Loss and recovery of trabecular bone in the distal radius following fracture — Immobilization of the upper limb in children

Summary Computed tomography of the human radius is performed using a special purpose scanning device which incorporates a radionuclide (¹²⁵I) as radiation source. Parameters describing the trabecular bone and the compact bone are determined at a distal and a diaphyseal measuring site respectively.Using this measurement technique changes in bone mineralization in the radius were studied in a group of 23 children following immobilization of an upper limb for fracture healing. An immobilization period of between three to six weeks resulted in a reduction of the relevant parameter value of up to 44% (mean 16%) in the distal part of the radius, whereas no significant change could be seen in the diaphyseal part of the same bone.Rapid remineralization of trabecular bone is indicated by the increase of the corresponding parameter value at a rate of up to several percent per week. However, in some of the patients studied complete normalization was not attained during the first six months following cast removal.This work has been supported in part by the Swiss National Science Foundation     

Scanning electron microscopy of cell surfaces following removal of extracellular material

The application of scanning electron microscopy to the study of cell surfaces is limited in intact tissues, because extracellular material may often obscure the details of nonluminal surfaces. To remove connective tissue elements we have treated human skin and both kidney, and an autonomic ganglion of the rat with hydrochloric acid and collagenase. Regional variations in the basal surface of the nephron are noted following removal of the basement membrane. The basilar interdigitations of the cells of the proximal tubule appeared as parallel ridges encircling the tubule. Ridges on the parietal epithelium of Bowman's capsule were randomly arranged and alternated with smooth surfaces. The dermal surface of the human epidermis has an alveolar or honeycomb appearance due to the elevation of the epidermal ridges and numerous pits for the dermal pegs. At higher magnifications the basal surface of cells of the stratum germinativum possessed numerous and irregular projections. Neurons with their processes are evident in the autonomic ganglion. The soma of the neurons are enclosed by flattened satellite cells. Irregular spaces between opposed satellite cells are interpreted as regions for the passage of processes related to the ganglion cells. Nodes of Ranvier were clearly seen along nerve fibers. Some pitting of the nerve fibers was also noted. The HCl-collagenase method has the advantage of the removal of collagen and basement membrane while preserving the structural integrity of the cell surface.     

Fractal analysis of lumbar vertebral cancellous bone architecture.

Osteoporosis is characterized by bone mineral density (BMD) decreasing and spongy bone rearrangement with consequent loss of elasticity and increased bone fragility. Quantitative computed tomography (QCT) quantifies bone mineral content but does not describe spongy architecture. Analysis of trabecular pattern may provide additional information to evaluate osteoporosis. The aim of this study was to determine whether the fractal analysis of the microradiography of lumbar vertebrae provides a reliable assessment of bone texture, which correlates with the BMD. The lumbar segment of the spine was removed from 22 cadavers with no history of back pain and examined with standard x-ray, traditional tomography, and quantitative computed tomography to measure BMD. The fractal dimension, which quantifies the image fractal complexity, was calculated on microradiographs of axial sections of the fourth lumbar vertebra to determine its characteristic spongy network. The relationship between the values of the BMD and those of the fractal dimension was evaluated by linear regression and a statistically significant correlation (R = 0.96) was found. These findings suggest that the application of fractal analysis to radiological analyses can provide valuable information on the trabecular pattern of vertebrae. Thus, fractal dimensions of trabecular bone structure should be considered as a supplement to BMD evaluation in the assessment of osteoporosis.